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Impianti di riscaldamento degli edifici NORMA E U R OP E A
Metodo per il calcolo dei requisiti energetici e dei rendimenti dell’impianto
UNI EN 15316-4-1
Parte 4-1: Sistemi di generazione per il riscaldamento degli ambienti, sistemi a combustione (caldaie) SETTEMBRE 2008 Heating systems in buildings
Method for calculation of system energy requirements and system efficiencies Part 4-1: Space heating generation systems, combustion systems (boilers) La norma è parte di una serie di norme sul metodo di calcolo dei requisiti energetici e dei rendimenti degli impianti di riscaldamento e di produzione di acqua calda sanitaria. La norma definisce i dati di ingresso richiesti, il metodo di calcolo e i dati in uscita per i sistemi di generazione del calore a combustione (caldaie) inclusi i relativi sistemi di controllo. La norma si applica anche ai casi di generazione combinata di riscaldamento e acqua calda sanitaria. Il caso di sola produzione di acqua calda sanitaria è trattato nella UNI EN 15316-3-3.
TESTO INGLESE
La presente norma è la versione ufficiale in lingua inglese della norma europea EN 15316-4-1 (edizione maggio 2008).
ICS UNI Ente Nazionale Italiano di Unificazione Via Sannio, 2 20137 Milano, Italia
91.140.10
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Pagina I
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PREMESSA NAZIONALE La presente norma costituisce il recepimento, in lingua inglese, della norma europea EN 15316-4-1 (edizione maggio 2008), che assume così lo status di norma nazionale italiana. La presente norma è stata elaborata sotto la competenza dell’ente federato all’UNI CTI - Comitato Termotecnico Italiano La presente norma è stata ratificata dal Presidente dell’UNI ed è entrata a far parte del corpo normativo nazionale il 25 settembre 2008.
Le norme UNI sono elaborate cercando di tenere conto dei punti di vista di tutte le parti interessate e di conciliare ogni aspetto conflittuale, per rappresentare il reale stato dell’arte della materia ed il necessario grado di consenso. Chiunque ritenesse, a seguito dell’applicazione di questa norma, di poter fornire suggerimenti per un suo miglioramento o per un suo adeguamento ad uno stato dell’arte in evoluzione è pregato di inviare i propri contributi all’UNI, Ente Nazionale Italiano di Unificazione, che li terrà in considerazione per l’eventuale revisione della norma stessa. Le norme UNI sono revisionate, quando necessario, con la pubblicazione di nuove edizioni o di aggiornamenti. È importante pertanto che gli utilizzatori delle stesse si accertino di essere in possesso dell’ultima edizione e degli eventuali aggiornamenti. Si invitano inoltre gli utilizzatori a verificare l’esistenza di norme UNI corrispondenti alle norme EN o ISO ove citate nei riferimenti normativi. UNI EN 15316-4-1:2008
© UNI
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EUROPEAN STANDARD
EN 15316-4-1
NORME EUROPÉENNE EUROPÄISCHE NORM
May 2008
ICS 91.140.10
English Version
Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies - Part 4-1: Space heating generation systems, combustion systems (boilers) Systèmes de chauffage dans les bâtiments - Méthode de calcul des besoins énergétiques et des rendements des systèmes - Partie 4-1 : Systèmes de génération de chauffage des locaux, systèmes de combustion (chaudières)
Heizanlagen in Gebäuden - Berechnung und Bewertung der Energieeffizienz von Systemen - Teil 4-1: Wärmeerzeugung für die Raumheizung, Verbrennungssysteme
This European Standard was approved by CEN on 11 April 2008. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36
© 2008 CEN
All rights of exploitation in any form and by any means reserved worldwide for CEN national Members.
UNI EN 15316-4-1:2008
B-1050 Brussels
Ref. No. EN 15316-4-1:2008: E
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EN 15316-4-1:2008 (E)
Contents
Page
Foreword..............................................................................................................................................................5 Introduction .........................................................................................................................................................7 1
Scope ......................................................................................................................................................8
2
Normative references ............................................................................................................................8
3 3.1 3.2
Terms and definitions ...........................................................................................................................9 Definitions ..............................................................................................................................................9 Symbols and units ...............................................................................................................................12
4 4.1 4.1.1 4.1.2 4.2 4.3 4.4 4.5 4.6 4.7 4.8
Principle of the method.......................................................................................................................14 Heat balance of the generation sub-system, including control of heat generation .....................14 Physical factors taken into account ..................................................................................................14 Calculation structure (input and output data) ..................................................................................14 Generation sub-system basic energy balance .................................................................................16 Auxiliary energy ...................................................................................................................................17 Recoverable, recovered and unrecoverable system thermal losses .............................................17 Calculation steps .................................................................................................................................18 Multiple boilers or generation sub-systems .....................................................................................18 Using net or gross calorific values ....................................................................................................19 Boundaries between distribution and generation sub-system.......................................................20
5 5.1 5.2 5.2.1 5.2.2 5.3 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5 5.3.6 5.3.7 5.3.8 5.3.9 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.4.6 5.4.7 5.4.8 5.4.9
Generation sub-system calculation ...................................................................................................22 Available methodologies ....................................................................................................................22 Seasonal boiler performance method based on system typology (typology method) ................22 Principle of the method.......................................................................................................................22 Calculation procedure .........................................................................................................................23 Case specific boiler efficiency method .............................................................................................24 Principle of the method.......................................................................................................................24 Input data to the method.....................................................................................................................24 Load of each boiler ..............................................................................................................................25 Generators with double service (space heating and domestic hot water production) ................27 Generator thermal losses ...................................................................................................................28 Total auxiliary energy..........................................................................................................................30 Recoverable generation system thermal losses ..............................................................................31 Fuel input..............................................................................................................................................32 Operating temperature of the generator ...........................................................................................32 Boiler cycling method .........................................................................................................................33 Principle of the method.......................................................................................................................33 Load factor ...........................................................................................................................................36 Specific thermal losses .......................................................................................................................36 Total thermal losses ............................................................................................................................39 Auxiliary energy ...................................................................................................................................40 Calculation procedure for single stage generators .........................................................................41 Multistage and modulating generators .............................................................................................41 Condensing boilers .............................................................................................................................44 Systems with multiple generators .....................................................................................................48
Annex A (informative) Sample seasonal boiler performance method based on system typology (typology method) ..............................................................................................................50 A.1 Scope ....................................................................................................................................................50 A.2 Limitations in use of this method ......................................................................................................50 A.3 Boiler typologies definition ................................................................................................................50
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EN 15316-4-1:2008 (E)
A.4 A.5
Procedure............................................................................................................................................. 51 Declaring values of seasonal efficiency ........................................................................................... 55
Annex B (informative) Additional formulas and default values for parametering the case specific boiler efficiency method ...................................................................................................... 56 B.1 Information on the method................................................................................................................. 56 B.1.1 Basic assumptions and intended use............................................................................................... 56 B.1.2 Known approximations....................................................................................................................... 56 B.2 Polynomial interpolation formulas .................................................................................................... 56 B.3 Generator efficiencies and stand-by losses..................................................................................... 57 B.3.1 Default values for generator efficiency at full load and intermediate load as a function of the generator power output ............................................................................................................... 57 B.3.2 Stand-by heat losses .......................................................................................................................... 59 B.3.3 Correction factor taking into account variation of efficiency depending on generator average water temperature................................................................................................................. 60 B.4 Auxiliary energy .................................................................................................................................. 61 B.5 Recoverable generation thermal losses ........................................................................................... 62 B.5.1 Auxiliary energy .................................................................................................................................. 62 B.5.2 Generator envelope............................................................................................................................. 62 B.5.3 Default data according to boiler location ......................................................................................... 63 Annex C (informative) Default values for parametering the boiler cycling method................................ 64 C.1 Information on the method................................................................................................................. 64 C.1.1 Basic assumptions and intended use............................................................................................... 64 C.1.2 Known approximations....................................................................................................................... 64 C.2 Default specific losses........................................................................................................................ 64 C.2.1 Default data for calculation of thermal losses through the chimney with burner on .................. 64 C.2.2 Default values for calculation of thermal losses through the generator envelope...................... 65 C.2.3 Default values for calculation of thermal losses through the chimney with the burner off........ 66 C.3 Default values for calculation of auxiliary energy ........................................................................... 67 C.4 Additional default data for multistage and modulating burners .................................................... 68 C.5 Additional default data for condensing boilers ............................................................................... 69 Annex D (informative) General part default values and information ........................................................ 71 D.1 Control factor....................................................................................................................................... 71 D.2 Intermediate load................................................................................................................................. 71 Annex E (informative) Calculation example for seasonal boiler performance method based on system typology .................................................................................................................................. 72 E.1 Introduction ......................................................................................................................................... 72 E.2 Input data ............................................................................................................................................. 72 E.3 Calculation procedure ........................................................................................................................ 73 E.4 Output data (connection to other parts of EN 15316)...................................................................... 74 Annex F (informative) Calculation examples for case specific boiler efficiency method ...................... 75 F.1 Condensing boiler example, data declared by the manufacturer .................................................. 75 F.1.1 Input data ............................................................................................................................................. 75 F.1.2 Calculation procedure ........................................................................................................................ 76 F.1.3 Output data (connection to other parts of EN 15316)...................................................................... 77 F.1.4 Conversion of net values to gross values ........................................................................................ 77 F.2 Standard boiler example, default data .............................................................................................. 78 F.2.1 Input data ............................................................................................................................................. 78 F.2.2 Calculation procedure ........................................................................................................................ 79 F.2.3 Output data (connection to other parts of EN 15316)...................................................................... 81 Annex G (informative) Calculation examples for boiler cycling method .................................................. 82 G.1 Modulating condensing boiler ........................................................................................................... 82 G.1.1 Input data ............................................................................................................................................. 82 G.1.2 Calculation procedure ........................................................................................................................ 84 G.1.3 Output data (connection to other parts of EN 15316)...................................................................... 88 G.2 Standard, on-off atmospheric boiler ................................................................................................. 88 G.2.1 Input data ............................................................................................................................................. 88
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EN 15316-4-1:2008 (E)
G.2.2 G.2.3
Calculation procedure .........................................................................................................................90 Output data (connection to other parts of EN 15316) ......................................................................91
Annex H (informative) Boiler water temperature calculation .....................................................................92 H.1 Boiler flow temperature and return temperature..............................................................................92 H.2 Boiler flow rate is the same as the distribution flow rate (no by-pass) .........................................93 H.3 Boiler flow rate is not the same as the distribution flow rate (by-pass connection or recirculation pump) .............................................................................................................................94 H.4 Parallel connection of boilers.............................................................................................................96 H.5 Boiler average water temperature......................................................................................................97 H.6 Example of water temperature calculation .......................................................................................98 Bibliography ......................................................................................................................................................99
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EN 15316-4-1:2008 (E)
Foreword This document (EN 15316-4-1:2008) has been prepared by Technical Committee CEN/TC 228 “Heating systems in buildings”, the secretariat of which is held by DS. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2008, and conflicting national standards shall be withdrawn at the latest by November 2008. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association (Mandate M/343), and supports essential requirements of EU Directive 2002/91/EC on the energy performance of buildings (EPBD). It forms part of a series of standards aimed at European harmonisation of the methodology for calculation of the energy performance of buildings. An overview of the whole set of standards is given in CEN/TR 15615, ‘Explanation of the general relationship between various CEN standards and the Energy Performance of Buildings Directive (EPBD)’ ("Umbrella document").' The subjects covered by CEN/TC 228 are the following: -
design of heating systems (water based, electrical, etc.);
-
installation of heating systems;
-
commissioning of heating systems;
-
instructions for operation, maintenance and use of heating systems;
-
methods for calculation of the design heat loss and heat loads;
-
methods for calculation of the energy performance of heating systems.
Heating systems also include the effect of attached systems such as hot water production systems. All these standards are systems standards, i.e. they are based on requirements addressed to the system as a whole and not dealing with requirements to the products within the system. Where possible, reference is made to other European or International Standards, a.o. product standards. However, use of products complying with relevant product standards is no guarantee of compliance with the system requirements. The requirements are mainly expressed as functional requirements, i.e. requirements dealing with the function of the system and not specifying shape, material, dimensions or the like. The guidelines describe ways to meet the requirements, but other ways to fulfil the functional requirements might be used if fulfilment can be proved. Heating systems differ among the member countries due to climate, traditions and national regulations. In some cases requirements are given as classes so national or individual needs may be accommodated. In cases where the standards contradict with national regulations, the latter should be followed.
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EN 15316-4-1:2008 (E)
EN 15316, Heating systems in buildings — Method for calculation of system energy requirements and system efficiencies consists of the following parts: Part 1: General Part 2-1: Space heating emission systems Part 2-3: Space heating distribution systems Part 3-1: Domestic hot water systems, characterisation of needs (tapping requirements) Part 3-2: Domestic hot water systems, distribution Part 3-3: Domestic hot water systems, generation Part 4-1: Space heating generation systems, combustion systems (boilers) Part 4-2: Space heating generation systems, heat pump systems Part 4-3: Heat generation systems, thermal solar systems Part 4-4: Heat generation systems, building-integrated cogeneration systems Part 4-5: Space heating generation systems, the performance and quality of district heating and large volume systems Part 4-6: Heat generation systems, photovoltaic systems Part 4-7: Space heating generation systems, biomass combustion systems According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
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EN 15316-4-1:2008 (E)
Introduction This European Standard presents methods for calculation of the additional energy requirements of a heat generation system in order to meet the distribution and/or storage sub-system demand. The calculation is based on the performance characteristics of the products given in product standards and on other characteristics required to evaluate the performance of the products as included in the system. This method can be used for the following applications: ⎯
judging compliance with regulations expressed in terms of energy targets;
⎯
optimisation of the energy performance of a planned heat generation system, by applying the method to several possible options;
⎯
assessing the effect of possible energy conservation measures on an existing heat generation system, by calculating the energy use with and without the energy conservation measure.
The user shall refer to other European Standards or to national documents for input data and detailed calculation procedures not provided by this European Standard.
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EN 15316-4-1:2008 (E)
1
Scope
This European Standard is part of a series of standards on the method for calculation of system energy requirements and system efficiencies of space heating systems and domestic hot water systems. The scope of this specific part is to standardise the: ⎯
required inputs;
⎯
calculation method;
⎯
resulting outputs;
for space heating generation by combustion sub-systems (boilers), including control. This European Standard is the general standard on generation by combustion sub-systems (boilers). If a combustion generation sub-system is within the scope of another specific part of the EN 15316 series (i.e. part 4.x), the latter shall be used. EXAMPLE
Biomass combustion generation sub-systems are within the scope of prEN 15316-4-7.
This European Standard is also intended for the case of generation for both domestic hot water production and space heating. The case of generation only for domestic hot water production is treated in EN 15316-33.
2
Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 297, Gas-fired central heating boilers - Type B11 and B11Bs boilers fitted with atmospheric burners of nominal heat input not exceeding 70 kW EN 303-5, Heating boilers – Part 5: Heating boilers for solid fuels, hand and automatically stocked, nominal heat output of up to 300 kW - Terminology, requirements, testing and marking EN 304, Heating boilers — Test code for heating boilers for atomizing oil burners EN 656, Gas-fired central heating boilers — Type B boilers of nominal heat input exceeding 70 kW but not exceeding 300 kW EN 15034:2006, Heating boilers - Condensing heating boilers for fuel oil EN 15035, Heating boilers - Special requirements for oil fired room sealed units up to 70 kW EN 15316-2-1, Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies – Part 2.1: Space heating emission systems EN 15316-2-3:2007, Heating systems in building - Method for calculation of system energy requirements and system efficiencies – Part 2.3: Space heating distribution systems
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EN 15316-4-1:2008 (E)
EN 15316-3-2, Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies – Part 3.2: Domestic hot water systems, distribution EN 15456, Heating boilers – Electrical power consumption for heat generators – System boundaries – Measurements EN 15603, Energy performance of buildings — Overall energy use and definition of energy ratings EN ISO 7345:1995, Thermal insulation - Physical quantities and definitions (ISO 7345:1987) EN ISO 13790, Thermal performance of buildings - Calculation of energy use for space heating (ISO 13790:2004)
3
Terms and definitions
3.1 Definitions For the purposes of this document, the terms and definitions given in EN ISO 7345:1995 and the following apply. 3.1.1 space heating process of heat supply for thermal comfort 3.1.2 domestic hot water heating process of heat supply to raise the temperature of the cold water to the intended delivery temperature 3.1.3 heated space room or enclosure which for the purposes of the calculation is assumed to be heated to a given set-point temperature or set-point temperatures 3.1.4 system thermal loss thermal loss from a technical building system for heating, cooling, domestic hot water, humidification, dehumidification, ventilation or lighting or other appliances that does not contribute to the useful output of the system NOTE Thermal energy recovered directly in the sub-system is not considered as a system thermal loss but as heat recovery and is directly treated in the related system standard.
3.1.5 auxiliary energy electrical energy used by technical building systems for heating, cooling, ventilation and/or domestic hot water to support energy transformation to satisfy energy needs NOTE 1
This includes energy for fans, pumps, electronics, etc.
NOTE 2
In EN ISO 9488 [4], the energy used for pumps and valves is called "parasitic energy".
3.1.6 heat recovery heat generated by a technical building system or linked to a building use (e.g. domestic hot water) which is utilised directly in the related system to lower the heat input and which would otherwise be wasted (e.g. preheating of the combustion air by flue gas heat exchanger)
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EN 15316-4-1:2008 (E)
3.1.7 total system thermal loss total of the technical system thermal loss, including recoverable system thermal losses 3.1.8 recoverable system thermal loss part of the system thermal loss which can be recovered to lower either the energy need for heating or cooling or the energy use of the heating or cooling system 3.1.9 recovered system thermal loss part of the recoverable system thermal loss which has been recovered to lower either the energy need for heating or cooling or the required energy use of the heating or cooling system 3.1.10 gross calorific value quantity of heat released by a unit quantity of fuel, when it is burned completely with oxygen at a constant pressure equal to 101 320 Pa, and when the products of combustion are returned to ambient temperature NOTE 1 This quantity includes the latent heat of condensation of any water vapour contained in the fuel and of the water vapour formed by the combustion of any hydrogen contained in the fuel. NOTE 2
According to ISO 13602-2 [5], the gross calorific value is preferred to the net calorific value.
NOTE 3
The net calorific value does not take into account the latent heat of condensation.
3.1.11 net calorific value gross calorific value minus latent heat of condensation of the water vapour in the products of combustion at ambient temperature 3.1.12 calculation step discrete time interval for the calculation of the energy needs and uses NOTE Typical discrete time intervals are one hour, one month or one heating and/or cooling season, operating modes, and bins.
3.1.13 calculation period period of time over which the calculation is performed NOTE
The calculation period can be divided into a number of calculation steps.
3.1.14 external temperature temperature of external air NOTE 1 For transmission heat transfer calculations, the radiant temperature of the external environment is supposedly equal to the external air temperature; long-wave transmission to the sky is calculated separately. NOTE 2 The measurement of external air temperature is defined in EN ISO 15927-1, Hygrothermal performance of buildings - Calculation and presentation of climatic data — Part 1: Monthly means of single meteorological elements.
3.1.15 heat transfer coefficient factor of proportionality of heat flow governed by a temperature difference between two environments
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EN 15316-4-1:2008 (E)
3.1.16 boiler gas, liquid or solid fuelled appliance designed to provide hot water for space heating. It may (but need not) be designed to provide domestic hot water heating as well 3.1.17 combustion power product of the fuel flow rate and the net calorific power of the fuel 3.1.18 low temperature boiler non-condensing boiler designed as a low temperature boiler and tested as a low temperature boiler as prescribed by the Council Directive 92/42/EEC about Boiler Efficiency [1] 3.1.19 condensing boiler boiler designed to make use of the latent heat released by condensation of water vapour in the combustion flue products. The boiler must allow the condensate to leave the heat exchanger in liquid form by way of a condensate drain NOTE Boilers not so designed, or without the means to remove the condensate in liquid form, are called ‘noncondensing’.
3.1.20 oil condensing boiler boiler designed to make use of the latent heat released by condensation of water vapour in the combustion flue products of a liquid fuel [EN 15034:2006] 3.1.21 modes of operation various modes in which the heating system can operate EXAMPLES
Set-point mode, cut-off mode, reduced mode, set-back mode, boost mode.
3.1.22 on/off boiler boiler without the capability to vary the fuel burning rate whilst maintaining continuous burner firing. This includes boilers with alternative burning rates set once only at the time of installation, referred to as range rating 3.1.23 multistage boiler boiler with the capability to vary the fuel burning rate stepwise whilst maintaining continuous burner firing 3.1.24 modulating boiler boiler with the capability to vary continuously (from a set minimum to a set maximum) the fuel burning rate whilst maintaining continuous burner firing
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EN 15316-4-1:2008 (E)
3.2 Symbols and units For the purposes of this document, the following symbols and units (Table 1) and indices (Table 2) apply. Table 1 – Symbols and units Symbol
Name of quantity
Unit
b
temperature reduction factor
-
c
coefficient
various
c
specific heat capacity
J/kg·K or a) Wh/kg·K
d
thickness
mm
E
energy in general (except quantity of heat, mechanical work and auxiliary (electrical) energy)
J or a) Wh
e
expenditure factor
-
f
factor
-
H
calorific value
J/mass unit or b) Wh/mass unit
H
heat transfer coefficient
W/K
k
factor
-
m
mass
kg
n
exponent
-
N
number of items
Integer
P
power in general including electrical power
W
Q
quantity of heat
J or a) Wh
t
time, period of time
s or a) h
V
volume
L
V'
volume flow
m³/s or a) m³/h
W
auxiliary (electrical) energy, mechanical work
J or a) Wh
x
relative humidity
%
X
volume fraction
%
Į
loss factor
%
ȕ
load factor
-
ǻ
prefix for difference
η
efficiency factor
%
12 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
Table 1 – Symbols and units Symbol
Name of quantity
Unit
θ
Celsius temperature
°C
ȡ
density
kg/m³
ĭ
heat flow rate, thermal power
W
a)
If seconds (s) is used as the unit of time, the unit for energy shall be J. If hours (h) is used as the unit of time, the unit for energy shall be Wh.
b)
Mass unit for fuel may be Stm³, Nm³ or kg.
Table 2 – Indices add
additional
gnr
generator
plt
pilot
air
air
grs
gross
pmp
after the combustion chamber
aux
auxiliary
H
heating
Pn
at nominal load
avg
average
i, j, k
indices
Px
at x load
br
before generator
in
input to sub-system
r
return
brm
boiler room
ins
insulation
rbl
recoverable
ch
chimney
lat
latent
ref
reference
ci
calculation step
ls
losses
rvd
recovered
cmb
combustion
m
mean
s
gross (calorific value)
cond
condensing
max
maximum
sat
saturation
corr
corrected / correction
mass
massic
sby
in stand-by operation
ctr
control
min
minimum
st
stoichiometric
dis
distribution
n
nominal
sto
storage
dry
dry gases
net
net
test
test conditions
em
emission
O2
oxygen
th
thermal
emr
emitter
off
off
W
heating system water
f
flow (temperature)
on
on
w
water
fg
flue gas
out
output from subsystem
wfg
water to flue gas
ge
generator envelope
P0
at zero load
z
indices
gen
generation subsystem
Pint
at intermediate load
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EN 15316-4-1:2008 (E)
Table 2 – Indices The indices specifying symbols for sub-system energy balance quantities are in the following order: ⎯
the first index represents the use (H = space heating, W = domestic hot water, etc.);
⎯
the second index represents the sub-system (gen = generation, dis = distribution, etc.);
⎯
the third index represents the balance item (ls = losses, in = input, aux = auxiliary, etc.).
Other indices may follow for more details (rvd = recovered, rbl = recoverable, etc.).
4
Principle of the method
4.1 Heat balance of the generation sub-system, including control of heat generation 4.1.1
Physical factors taken into account
The calculation method of the generation sub-system takes into account heat losses and/or recovery due to the following physical factors: ⎯
heat losses to the chimney (or flue gas exhaust) during total time of generator operation (running and stand-by);
⎯
heat losses through the generator(s) envelope during total time of generator operation (running and stand-by);
⎯
auxiliary energy.
The relevance of these effects on the energy requirements depends on: ⎯
type of heat generator(s);
⎯
location of heat generator(s);
⎯
part load ratio;
⎯
operating conditions (temperature, control, etc.);
⎯
control strategy (on/off, multistage, modulating, cascading, etc.).
4.1.2
Calculation structure (input and output data)
The calculation method of this standard shall be based on the following input data from other parts of the EN 15316-X-X series of standards: ⎯
heat demand of the distribution sub-system(s) for space heating ΣQH,dis,in, calculated according to EN15316-2-3;
⎯
heat demand of the distribution sub-system(s) for domestic hot water ΣQW,dis,in, calculated according to EN 15316-3-2, where appropriate.
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The performance of the generation sub-system may be characterised by additional input data to take into account: ⎯
type and characteristics of the generation sub-system;
⎯
generator settings;
⎯
type of the generation control system;
⎯
location of the generator;
⎯
operating conditions;
⎯
heat requirement.
Based on these data, the following output data are calculated by this standard: ⎯
fuel heat requirement, EH,gen,in;
⎯
total generation thermal losses (flue gas and generator envelope), QH,gen,ls;
⎯
recoverable generation thermal losses, QH,gen,ls,rbl;
⎯
generation auxiliary energy, WH,gen,aux.
Figure 1 shows the calculation inputs and outputs of the generation sub-system.
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EN 15316-4-1:2008 (E)
Key SUB HF QH,gen,out EH,gen,in
Generation sub-system balance boundary Heating fluid balance boundary (see equation (1)) Generation sub-system heat output (input to distribution sub-system(s)) Generation sub-system fuel input (energyware)
WH,gen,aux QH,gen,aux,rvd
Generation sub-system total auxiliary energy Generation sub-system recovered auxiliary energy
QH,gen,ls QH,gen,ls,rbl
Generation sub-system total thermal losses Generation sub-system thermal loss recoverable for space heating
QH,gen,ls,th,rbl QH,gen,aux,rbl
Generation sub-system thermal loss (thermal part) recoverable for space heating Generation sub-system recoverable auxiliary energy
QH,gen,ls,th,nrbl QH,gen,aux,nrbl
Generation sub-system thermal loss (thermal part) non recoverable Generation sub-system non recoverable auxiliary energy
NOTE
Figures shown are sample percentages.
Figure 1 – Generation sub-system inputs, outputs and energy balance
4.2 Generation sub-system basic energy balance The basic energy balance of the generation sub-system is given by
E H,gen,in = QH,gen,out − QH,gen,aux,rvd + QH,gen,ls
(1)
where EH,gen,in
heat requirement of the generation sub-system (fuel input);
QH,gen,out
heat supplied to the distribution sub-systems (space heating and domestic hot water);
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EN 15316-4-1:2008 (E)
QH,gen,aux,rvd auxiliary energy recovered by the generation sub-system (i.e. pumps, burner fan, etc.); QH,gen,ls
total losses of the generation sub-system (through the chimney, generator envelope, etc.).
NOTE QH,gen,ls takes into account flue gas and generator envelope losses, part of which may be recoverable according to location. See 4.4, 5.3.5 and 5.4.4.
If there is only one generation sub-system
QH,gen,out = f ctrl ⋅ ¦iQH,dis,in,i + ¦ j QW,dis,in, j
(2)
where fctrl
factor taking into account emission control losses. Default value of fctrl is given in Table D.1. Other values may be specified in a national annex, provided that emission control losses has not been already taken into account in the emission part (EN 15316-2-1) or in the distribution part (EN 15316-2-3).
If there are multiple generation sub-systems or multiple boilers, see 4.6, 5.3.3 and 5.4.9. If the generator provides heat for heating and domestic hot water, the index H shall be replaced by HW. In the following only H is used for simplicity.
4.3 Auxiliary energy Auxiliary energy is the energy, other than fuel, required for operation of the burner, the primary pump and any equipment whose operation is related to operation of the heat generation sub-system. Auxiliary energy is counted in the generation part as long as no transport energy from the auxiliary equipment is transferred to the distribution sub-system (example: zero–pressure distribution array). Such auxiliary equipment can be (but need not be) an integral part of the generator. Auxiliary energy, normally in the form of electrical energy, may be partially recovered as heat for space heating or for the generation sub-system. Examples of recoverable auxiliary energy: ⎯
electrical energy transmitted as heat to the water of the primary circuit;
⎯
part of the electrical energy for the burner fan.
Example of non-recoverable auxiliary energy: ⎯
electrical energy for electric panel auxiliary circuits, if the generator is installed outside the heated space.
4.4 Recoverable, recovered and unrecoverable system thermal losses Not all of the calculated system thermal losses are necessarily lost. Some of the losses are recoverable and part of the recoverable system thermal losses are actually recovered. Example of recoverable system thermal losses are: ⎯
thermal losses through the envelope of a generator installed within the heated space.
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Examples of non-recoverable system thermal losses are: ⎯
thermal losses through the envelope of a generator installed outside the heated space;
⎯
thermal losses through the chimney installed outside the heated space.
Recovery of system thermal losses to the heated space can be accounted for: ⎯
either as a reduction of total system thermal losses within the specific part (simplified method);
⎯
or, by taking into account recoverable system thermal losses as gains (holistic method) or as a reduction of the energy use according to EN 15603.
This European Standard allows both approaches. Generation system thermal losses recovered by the generation sub-system are directly taken into account in the generation performance. EXAMPLE
Combustion air preheating by flue gas losses.
4.5 Calculation steps The objective of the calculation is to determine the energy input of the heating generation sub-system for the entire calculation period (usually one year). This may be done in one of the following two different ways: ⎯
by using average (usually yearly) data for the entire calculation period;
⎯
by dividing the calculation period into a number of calculation steps (e.g. months, weeks, bins, operation modes as defined in EN ISO 13790) and perform the calculations for each step using step-dependent values and adding up the results for all the steps over the calculation period.
NOTE Generation efficiency is strongly dependent on the load factor and this relationship is not linear. To achieve precision, the calculation steps should not be longer than 1 month.
4.6 Multiple boilers or generation sub-systems The primary scope of this European Standard is to calculate losses, fuel requirement and auxiliary energy requirements for an individual boiler. If there are multiple generation sub-systems, the general part allows for a modular approach to take into account cases where: ⎯
a heating system is split up in zones with several distribution sub-systems;
⎯
several heat generation sub-systems are available.
EXAMPLE 1
A separate circuit may be used for domestic hot water production.
EXAMPLE 2
A boiler may be used as a back-up for a solar and/or cogeneration sub-system(s).
In these cases, the total heat requirement of the connected distribution sub-systems ȈiQX,dis,in,i shall equal the total heat output of the generation sub-systems ȈiQX,gen,out,j:
¦Q j
X,gen,out, j
= ¦iQX,dis,in,i
(3)
NOTE X is used as an index in equation (3) to mean space heating, domestic hot water heating or other building services requiring heat from a generation sub-system.
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If there are several generation sub-systems, the total heat demand of the distribution sub-system(s) shall be distributed among the available generation sub-systems. The calculation described in 5.2, 5.3, 5.4 and/or other relevant parts of EN 15316-4 shall be performed independently for each heat generation device j, on the basis of QH,gen,out,j. Criteria for distribution of the total heat demand among the available generation sub-systems may be based on physical, efficiency or economic considerations. EXAMPLE 3
Solar or heat pump sub-system maximum heat output.
EXAMPLE 4
Heat pumps or cogeneration optimum (either economic or energetic) performance range.
Appropriate criteria for specific types of generation sub-systems can be found in the relevant parts of the EN 15316-4-X series of standards. Procedures to split the load among multiple combustion generators (boilers) are given for basic cases in 5.3.3 and 5.4.9. EXAMPLE 5
Given ȈQH,dis,in, the maximum output of a solar generation system QH,sol,out should be calculated first, and subsequently the heat output that can be provided by a cogeneration system is added Qchp,gen,out. The rest (QH,gen,out,boil = ȈQH,dis,in - QH,sol,out - Qchp,gen,out, see Figure 2) is attributed to boilers and may be further split among multiple boilers according to 5.3.3 and 5.4.9.
Figure 2 – Example of load splitting among generation sub-systems
4.7 Using net or gross calorific values Calculations described in 5 may be performed according to net or gross calorific values. All parameters and data shall be consistent with this option. If the calculation of the generation sub-system is performed according to data based on fuel net calorific values Hi, total losses QH,gen.ls,net, non recoverable thermal losses QH,gen,ls,th,nrbl,net and generation sub-system energyware EH,gen,in,net (i.e. fuel input for combustion systems) based on net calorific values may be converted to values QH,gen,ls,grs, QH,gen,ls,th,nrbl,grs and EH,gen,in,grs based on gross calorific values Hs by addition of the latent heat of condensation Qlat according to the following:
Qlat = E H,gen,in,net ⋅
Hs − Hi Hi
(4)
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E H,gen,in,grs = E H,gen,in,net + Qlat
(5)
QH,gen,ls,grs = QH,gen,ls,net + Qlat
(6)
QH, gen, ls, th, nrbl,grs = QH, gen,ls, th, nrbl, net + Qlat
(7)
4.8 Boundaries between distribution and generation sub-system Boundaries between generation sub-system and distribution sub-system should be defined according to the following principles. If the generation sub-system includes the generator only (i.e. there is no pump within the generator), the boundary with the distribution sub-system is represented by the hydraulic connection of the boiler, as shown in Figure 3.
Key gen dis
generation sub-system distribution sub-system
em
emission sub-system
Figure 3 – Sample sub-systems boundaries A pump physically within the boiler is however considered part of the distribution sub-system if it contributes to the flow of heating medium to the emitters. An example is shown in Figure 4.
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Key gen dis
generation sub-system distribution sub-system
em
emission sub-system
Figure 4 – Sample sub-systems boundaries Only pumps dedicated to generator requirements may be considered within the generation sub-system. An example is shown in Figure 5.
Key gen
generation sub-system
dis em
distribution sub-system emission sub-system
Figure 5 – Sample sub-systems boundaries
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5
Generation sub-system calculation
5.1
Available methodologies
In this standard, three performance calculation methods for the heat generation sub-system are described corresponding to different use (simplified or detailed estimation, on site measurements, etc.). The calculation methods differ with respect to: ⎯
required input data;
⎯
operating conditions taken into account;
⎯
calculation steps applied.
For the first method (see 5.2), the considered calculation step is the heating season. The performance calculation is based on the data related to the Council Directive 92/42/EEC about Boiler Efficiency [1]. The operation conditions taken into account (climate, distribution sub-system connected to the generator, etc.) are approximated by typology of the considered region and are not case specific. If this method is to be applied, an appropriate national annex with the relevant values shall be available. The second method (see 5.3) is also based on the data related to the Council Directive 92/42/EEC about Boiler Efficiency [1], but supplementary data are needed in order to take into account the specific operation conditions of the individual installation. The considered calculation step can be the heating season but may also be a shorter period (month, week and/or the operation modes according to EN ISO 13790). The method is not limited and can be used with the default values given in informative Annex B. The third method (see 5.4) distinguishes in a more explicit way the losses of a generator which occurs during boiler cycling (i.e. combustion losses). Some of the parameters can be measured on site. This method is well adapted for existing buildings and to take into account condensation heat recovery according to operating conditions. The calculation method to be applied is chosen as a function of the available data and the objectives of the calculation. Further details on each method are given in the respective parametering informative Annexes (A, B and C).
5.2
Seasonal boiler performance method based on system typology (typology method)
5.2.1
Principle of the method
This method assumes that ⎯
climatic conditions,
⎯
operation modes,
⎯
typical occupancy patterns of the relevant building sector,
have been considered and are incorporated in a procedure to convert standard test results of boiler efficiency (as used for the Council Directive 92/42/EEC about Boiler Efficiency [1]) into a seasonal efficiency for the relevant building sector. The stages within the seasonal efficiency calculation procedure are: a)
adapt test results for uniformity, taking account of boiler type, fuel and specific conditions for testing imposed by the Council Directive 92/42/EEC about Boiler Efficiency [1] and the relevant standards;
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b)
adjust for annual performance in installed conditions, taking account of regional climate, operation modes and occupancy patterns typical of the relevant building sector;
c)
perform the calculations and determine fuel heat requirement, total generation thermal loss (as an absolute value), recoverable generation thermal loss, auxiliary energy, recoverable auxiliary energy.
The procedure allows for national characteristics of the relevant building sector. 5.2.2 5.2.2.1
Calculation procedure Selection of appropriate seasonal efficiency procedure
A seasonal efficiency calculation procedure is selected from the appropriate national annex on the basis of the following information: ⎯
region (climate) in which the building is situated;
⎯
building sector (housing, commercial, industrial, etc).
The procedure shall include limitation in use, relevant boundary conditions and reference to validation data. The procedure shall be defined in a national annex. If there is no appropriate national annex, this method cannot be used. Annex A (informative) is an example of a seasonal efficiency calculation procedure, known as SEDB_UK, and it represents conditions in the housing sector of the UK. 5.2.2.2
Input information required for the seasonal efficiency procedure
Input information for the procedure shall comprise: ⎯
heat demand of the distribution sub-system(s) for space heating ΣQH,dis,in calculated according to EN15316-2-3;
⎯
heat demand of the distribution sub-system(s) for domestic hot water ΣQW,dis,in calculated according to EN 15316-3-2, where appropriate.
Input information for the procedure may comprise: ⎯
full-load and 30 % part-load efficiency test results produced in accordance with standard tests as required for the Council Directive 92/42/EEC about Boiler Efficiency [1];
⎯
boiler type (condensing or not, combination or not, hot water store included or not, etc);
⎯
fuel used (natural gas, LPG, oil, etc);
⎯
boiler power output (maximum and minimum if a range);
⎯
ignition method (permanent pilot flame or not);
⎯
burner type (modulating, multistage or on/off);
⎯
internal store included in efficiency tests (yes/no);
⎯
store characteristics (volume, insulation thickness).
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5.2.2.3
Output information obtained from the seasonal efficiency procedure
Output information from the procedure shall comprise: ⎯
EH,gen,in
fuel heat requirement;
⎯
WH,gen,aux
auxiliary energy;
⎯
QH,gen,ls,rbl
recoverable system thermal losses for space heating.
5.3
Case specific boiler efficiency method
5.3.1
Principle of the method
This method is related to the Council Directive 92/42/EEC about Boiler Efficiency [1] and is based on the following principle: a) data are collected for three basic load factors or power outputs: ⎯
Șgnr,Pn efficiency at 100 % load;
⎯
Șgnr,Pint efficiency at intermediate load;
⎯ Ɏgnr,ls,P0 losses at 0 % load; b)
efficiency and losses data are corrected according to boiler operating conditions (temperature);
c)
losses power at 100 % load Ɏgnr,ls,Pn and at intermediate load Ɏgnr,ls,Pint are calculated according to corrected efficiencies;
d)
calculation of losses power corresponding to the actual power output is made by linear or polynomial interpolation between losses powers for the three basic power outputs;
NOTE For the case specific boiler efficiency method, all powers and the load factor ȕgnr are referred to generation sub-system output.
e)
auxiliary energy is calculated taking into account the actual power output of the boiler;
f)
recoverable generator envelope thermal losses are calculated according to a tabulated fraction of standby heat losses and boiler location;
g)
recoverable auxiliary energy is added to recoverable generator envelope thermal losses to provide total recoverable thermal losses.
5.3.2
Input data to the method
5.3.2.1
Boiler data
The boiler is characterised by the following valuesҏ: ⎯
ɎPn
generator output at full load;
⎯
Șgnr,Pn
generator efficiency at full load;
⎯
șgnr,w,test,Pn generator average water temperature at test conditions for full load;
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⎯
fcorr,Pn
correction factor of full-load efficiency;
⎯
ɎPint
generator output at intermediate load;
⎯
Șgnr,Pint
generator efficiency at intermediate load;
⎯
șgnr,w,test,Pint generator average water temperature at test conditions for intermediate load;
⎯
fcorr,Pint
correction factor of intermediate load efficiency;
⎯
Ɏgnr,ls,P0
stand-by heat loss at test temperature difference Δșgnr,test,P0;
⎯
Δθgnr,test,P0 difference between mean boiler temperature and test room temperature at test conditions;
⎯
Paux,gnr,Pn
⎯
Paux,gnr,Pint power consumption of auxiliary devices at intermediate load;
⎯
Paux,gnr,P0
stand-by power consumption of auxiliary devices;
⎯
șgnr,w,min
minimum operating boiler temperature.
power consumption of auxiliary devices at full load;
Data to characterise the boiler shall be taken from one of the following sources, listed in priority order: a)
product data from the manufacturer, if the boiler has been tested according to EN 297, EN 303-5, EN 304, EN 656, EN 15034, EN 15035 and/or EN 15456 (auxiliary power data);
b)
default data from the relevant national annex;
c)
default data from Annexes B or D.
It shall be recorded whether or not the efficiency values include auxiliary energy recovery. 5.3.2.2
Actual operating conditions
Actual operating conditions are characterised by the following values: ⎯
QH,gen,out
heat output to the heat distribution sub-system(s);
⎯
θgnr,w,m
average water temperature in the boiler;
⎯
θgnr,w,r
return water temperature to the boiler (for condensing boilers);
⎯
θi,brm
boiler room temperature;
⎯
bbrm
temperature reduction factor depending on the location of the generator.
5.3.3 5.3.3.1
Load of each boiler Generation sub-system average power
Generation sub-system average power ɎH,gen,out is given by:
ĭH,gen,out =
QH,gen,out t gen
(8)
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where tgen 5.3.3.2
total time of generator(s) operation. Single boiler generation sub-system
If there is only one generator installed, the load factor ȕgnr is given by:
ȕ gnr =
ĭH,gen,out
(9)
ĭPn
where ɎPn 5.3.3.3
nominal power output of the generator. Multiple boilers generation sub-system
5.3.3.3.1 General If there are several boilers installed, distribution of the load among boilers depends on control. Two types of control are distinguished: ⎯
without priority;
⎯
with priority.
5.3.3.3.2 Multiple generators without priority All generators are running at the same time and therefore the load factor ȕgnr is the same for all boilers and is given by:
ȕ gnr =
ĭH,gen,out
¦ĭ i
(10)
Pn,i
where ɎPn,i
nominal power output of generator i at full load.
5.3.3.3.3 Multiple generators with priority The generators of higher priority are running first. A given generator in the priority list is running only if the generators of higher priority are running at full load (ȕgnr,i = 1). If all boilers have the same power output ɎPn, the number of running generators Ngnr,on is given by:
§ ĭH,gen,out N gnr,on = int ¨¨ © ĭPn
· ¸¸ ¹
(11)
Otherwise running boilers have to be determined so that 0 < ȕgnr,j < 1 (see equation (10))
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EN 15316-4-1:2008 (E)
The load factor ȕgnr,j for the intermittent running generator is calculated by:
β gnr, j =
ĭH,gen,out −
N gnr, on
¦ĭ
Pn,i
i =1
ĭPn, j
(12)
where
5.3.4
ɎPn,i
nominal power output of generator i running at full load;
ɎPn,j
nominal power output of intermittent running generator.
Generators with double service (space heating and domestic hot water production)
During the heating season, the heat generator can produce energy for the space heating installation and the domestic hot water (double service). Calculation of the thermal losses for a generator running for domestic hot water service only, is specified in the domestic hot water part of this standard, EN 15316-3-3 [3]. The domestic hot water generation also influences the heating part of a double service generator in respect of: ⎯
running temperature of the generator;
⎯
running time;
⎯
load.
The running temperature of the generator may be modified if domestic hot water production is required. The dynamic effects of this temperature modification (heating up, cooling down) are neglected in this part of the standard. The needs for domestic hot water production may extend the heating up period, if the generator is already running at nominal power. The impacts on the time periods (heating up, normal mode, etc.) defined in EN ISO 13790 are neglected. The domestic hot water production increases the load of the double service generator. This effect is taken into account by increasing the generation sub-system load during the considered period by:
QHW,gen,out = f ctrl ⋅ QH,dis,in + QW,dis,in
(13)
and using QHW,gen,out instead of QH,gen,out in equation (8). NOTE
Equation (13) is the same as equation (2).
In general, the considered calculation period is the same for domestic hot water production and for space heating. However, if the domestic hot water is produced only during specific operation modes (e.g. only during normal mode or if a priority control is fitted), the calculation may be performed independently for the two operation modes: ⎯
once taking into account tgnr,H (operation time for space heating) and ɎPx,H (calculated with QH,dis,in and tgnr,H) and operating conditions for space heating service;
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EN 15316-4-1:2008 (E)
⎯
once taking into account tgnr,W (operation time for domestic hot water production) and ɎPx,W (calculated with QW,dis,in and tgnr,W ) and operating conditions for domestic hot water production.
Losses, auxiliary energy and fuel input for the two operation modes are summed up at the end of the calculation. 5.3.5
Generator thermal losses
5.3.5.1
Generator thermal loss calculation at full load
The efficiency at full load Șgnr,Pn is measured at a reference generator average water temperature θgnr,w,test,Pn. This efficiency has to be adjusted to the actual generator average water temperature of the individual installation. The temperature corrected efficiency at full load Șgnr,Pn,corr is calculated by:
Șgnr,Pn,corr = Șgnr,Pn + f corr,Pn ⋅ (ș gnr,w, test,Pn − ș gnr,w, m )
(14)
where Șgnr,Pn
generator efficiency at full load. If the performance of the generator has been tested according to relevant EN standards (see 5.3.2.1), it can be taken into account. If no values are available, default values shall be found in the relevant national annex or in B.3.1;
fcorr,Pn
correction factor taking into account variation of the full load efficiency as a function of the generator average water temperature. The value should be given in a national annex. In the absence of national values, default values are given in B.3.3. If the performance of the generator has been tested according to relevant EN standards (see 5.3.2.1), it can be taken into account;
șgrn,w,test,Pn generator average water temperature at test conditions for full load (see B.3.3); șgnr,w,m
generator average water temperature as a function of the specific operating conditions (see 5.3.9).
In order to simplify the calculations, the efficiencies and heat losses determined at test conditions are adjusted to the actual generator average water temperature. It is allowed, as it is physically correct, to adjust the performance at each load according to the actual generator average water temperature of each load. The corrected generator thermal loss at full load Ɏgnr,ls,Pn,corr is calculated by:
ĭgnr,ls,Pn,corr =
(100 − Șgnr,Pn,corr ) Șgnr,Pn,corr
⋅ ĭPn
(15)
where ɎPn 5.3.5.2
generator output at full load. Generator thermal loss calculation at intermediate load
The efficiency at intermediate load Șgnr,Pint is measured at a reference generator average water temperature
θgnr,w,test,Pint. This efficiency has to be adjusted to the actual generator average water temperature of the individual installation. The temperature corrected efficiency at intermediate load Șgnr,Pint,corr is calculated by:
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EN 15316-4-1:2008 (E)
Șgnr,Pint,corr = Șgnr,Pint + f corr,Pint ⋅ (ș gnr,w, test,Pint − ș gnr,w,m )
(16)
where Șgnr,Pint
generator efficiency at intermediate load. If the performance of the generator has been tested according to relevant EN standards (see 5.3.2.1), it can be taken into account. If no values are available, default values shall be found in the relevant national annex or in B.3.1;
fcorr,Pint
correction factor taking into account variation of the efficiency as a function of the generator average water temperature. The value should be given in a national annex. In the absence of national values, default values are given in B.3.3. If the performance of the generator has been tested according to relevant EN standards (see 5.3.2.1), it can be taken into account;
șgnr,w,test,Pint generator average water temperature (or return temperature to the boiler for condensing boilers) at test conditions for intermediate load (see B.3.3); șgnr,w,m
generator average water temperature (or return temperature to the generator for condensing boilers) as a function of the specific operating conditions (see 5.3.9).
The intermediate load depends on the generator type. Default values are given in D.2. The corrected generator thermal loss at intermediate load Φgnr,ls,Pint,corr is calculated by:
ĭgnr,ls,Pint,corr =
(100 − Șgnr,Pint,corr ) Șgnr,Pint,corr
⋅ ĭPint
(17)
where ɎPint 5.3.5.3
generator output at intermediate load. Generator thermal loss calculation at 0 % load
The generator stand-by heat loss at 0 % load ĭgnr,ls,P0 is determined for a test temperature difference according to relevant testing standards (i.e. EN 297, EN 483/A2, EN 303, EN 13836 and EN 15043). If the performance of the generator has been tested according to relevant EN standards (see 5.3.2.1), it can be taken into account. If no manufacturer or national annex data are available, default values are given in B.3.2. The temperature corrected generator thermal loss at 0 % load Φ gnr,ls,P0,corr is calculated by: 1, 25
ĭgnr,ls, P0, corr
§ș · −ș = ĭgnr, ls, P0 ⋅ ¨ gnr, w, m i, brm ¸ ¨ ǻș ¸ gnr, test, P0 © ¹
(18)
where Ɏgnr,ls,PO
stand-by heat loss at 0 % load at test temperature difference Δșgnr,test,P0;
șgnr,w,m
generator average water temperature (or return temperature to the generator for condensing boilers) as a function of the specific operating conditions (see 5.3.9);
și,brm
indoor temperature of the boiler room. Default values are given in B.5.3;
Δșgnr,test,P0 difference between generator average water temperature and test room temperature at test conditions. Default values are given in B.3.2.
29 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
Boiler thermal loss at specific load ratio ȕgnr and power output ɎPx
5.3.5.4
The specific load ratio ȕgnr of each boiler is calculated according to 5.3.3 and 5.3.4. The actual power output ɎPx of the boiler is given by
Φ Px = Φ Pn ⋅ β gnr
(19)
If ɎPx is between 0 (ȕgnr = 0) and ɎPint (intermediate load, ȕgnr = ȕint = ɎPint/ɎPn), the generator thermal loss Ɏgnr,ls,Px is calculated by:
ĭgnr,ls,Px =
ĭPx ⋅ (ĭgnr,ls,Pint,corr − ĭgnr,ls,P0,corr ) + ĭgnr,ls,P0,corr ĭPint
(20)
If ɎPx is between ɎPint and ɎPn (full load, ȕgnr = 1), the generator thermal loss Φgnr,ls,Px is calculated by:
ĭgnr,ls, Px =
ĭPx − ĭPint ⋅ (ĭgnr, ls, Pn, corr − ĭgnr,ls, Pint, corr ) + ĭgnr,ls, Pint, corr ĭPn − ĭPint
(21)
Φgnr,ls,Px may also be calculated by 2nd order polynomial interpolation. A formula for such interpolation is given in B.2. The total boiler thermal loss Qgnr,ls during the considered operation time tgnr of the boiler is calculated by:
Qgnr,ls = ĭgnr,ls,Px ⋅ t gnr 5.3.5.5
(22)
Total generation thermal losses
Total generation sub-system thermal losses are the sum of boiler thermal losses:
QH,gen,ls = ¦ Qgnr,ls 5.3.6
(23)
Total auxiliary energy
The total auxiliary energy for a boiler is given by:
Wgnr,aux = Paux,Px ⋅ t gnr + Paux,off ⋅ (t ci − t gnr )
(24)
where Paux,off
auxiliary power when the generation system is inactive. If the generator is electrically isolated when inactive, Paux,off = 0. Otherwise Paux,off = Paux,P0;
tci
is the calculation interval;
tgnr
is the operation time of the generator within the calculation interval tci.
The average auxiliary power for each boiler Paux,Px is calculated by linear interpolation, according to the boiler load ȕgnr (calculated according to 5.3.3), between: ⎯
Paux,Pn
auxiliary power of the boiler at full load (ȕgnr = 1),
⎯
Paux,Pint
auxiliary power of the boiler at intermediate load (ȕgnr = ȕint),
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EN 15316-4-1:2008 (E)
⎯
Paux,P0
auxiliary power of the boiler at stand-by (ȕgnr = 0),
measured according to EN 15456. If no declared or measured data is available, default values are given in B.4. NOTE
The corresponding symbols in EN 15456 are: Paux,Pn = Paux,100, Paux,Pint = Paux,30 and Paux,P0 = Paux,sb.
If 0 ≤ ȕgnr ≤ ȕint then Paux,Px is given by:
Paux,Px = Paux,P0 +
ȕ gnr ȕint
⋅ (Paux,Pint − Paux,P0 )
(25)
If ȕint < ȕgnr ≤ 1 then Paux,Px is given by:
Paux,Px = Paux,Pint +
ȕ gnr − ȕint 1 − ȕint
⋅ (Paux,Pn − Paux,Pint )
(26)
The generation sub-system auxiliary energy WH,gen,aux is given by:
WH,gen,aux = ¦Wgnr,aux 5.3.7 5.3.7.1
(27)
Recoverable generation system thermal losses Auxiliary energy
For the recoverable auxiliary energy, a distinction is made between: ⎯
recoverable auxiliary energy transmitted to the heating medium (e.g. water). It is assumed that the auxiliary energy transmitted to the energy vector is totally recovered;
⎯
recoverable auxiliary energy transmitted to the heated space.
The recovered auxiliary energy transmitted to the heating medium Qgnr,aux,rvd is calculated by:
Qgnr, aux, rvd = Wgnr,aux ⋅ f rvd,aux where frvd,aux
(28)
part of the auxiliary energy transmitted to the distribution sub-system. The value should be given in a national annex. In the absence of national values, a default value is given in B.5.1. If the performance of the generator has been declared by the manufacturer, it can be taken into account.
Recovered auxiliary energy already taken into account in efficiency data shall not be calculated for recovery again. It has to be calculated for auxiliary energy need only. NOTE Measured efficiency according to relevant standards usually includes the effect of heat recovered from auxiliary energy for oil heating, combustion air fan, primary pump (i.e. heat recovered from auxiliaries is measured with the useful output).
The recoverable auxiliary energy transmitted to the heated space Qgnr,aux,rbl is calculated by:
Qgnr, aux, rbl = Wgnr, aux ⋅ (1 − bbrm ) ⋅ f rbl, aux
(29)
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EN 15316-4-1:2008 (E)
where frbl,aux
temperature reduction factor depending on location of the generator. The value of bbrm should be given in a national annex. In the absence of national values, a default value is given in B.5.3.
bbrm
5.3.7.2
part of the auxiliary energy not transmitted to the distribution sub-system. The value should be given in a national annex. In the absence of national values, a default value is given in B.5.1. If the performance of the generator has been certified, it can be taken into account;
Generator thermal loss (generator envelope)
Only the thermal losses through the generator envelope are considered as recoverable and depend on the burner type. For oil and gas fired boilers, the thermal losses through the generator envelope are expressed as a fraction of the total stand-by heat losses. The recoverable thermal losses through the generator envelope Qgnr,ls,env,rbl are calculated by:
Qgnr, ls, env, rbl = ĭgnr, ls, P0, corr ⋅ (1 − bbrm ) ⋅ f gnr, env ⋅ tgnr where fgnr,env
(30)
thermal losses through the generator envelope expressed as a fraction of the total stand-by heat losses. The value of fgnr,env should be given in a national annex. In the absence of national values, default values are given in B.5.2. If the performance of the generator has been tested, it can be taken into account;
bbrm
temperature reduction factor depending on location of the generator. The value of bbrm should be given in a national annex. In the absence of national values, a default value is given in B.5.3;
tgnr
boiler operation time.
5.3.7.3
Total recoverable generation system thermal losses
The total recovered auxiliary energy QH,gen,aux,rvd is calculated by:
QH,gen,aux,rvd = ¦ Qgnr,aux,rvd
(31)
The total recoverable generation system thermal losses QH,gen,ls,rbl are calculated by:
QH, gen, ls, rbl = ¦ Qgnr, ls,env, rbl + ¦ Qgnr, aux, rbl 5.3.8
(32)
Fuel input
Fuel heat input EH,gen,in is calculated according to equation (1). 5.3.9
Operating temperature of the generator
The operating temperature of the generator depends on: ⎯
type of control;
⎯
technical limit of the generator (taken into account by the temperature limitation);
⎯
temperature of the distribution sub-system connected to the generator.
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EN 15316-4-1:2008 (E)
The effect of control on the boiler is assumed to be a varying average temperature of the heat emitters. Therefore three types of boiler control are taken into account: ⎯
constant water temperature;
⎯
variable water temperature depending on the inside temperature;
⎯
variable water temperature depending on the outside temperature.
The operating temperature of the generator is calculated by:
ș gnr, w, x,ltd = max( ș gnr, w, min , ș gnr, w, x )
(33)
where șgnr,,w,min
minimum operating boiler temperature for each generator. If the installation is equipped with several generators, the running temperature limitation used for calculation is the highest value of the temperature limitations of the generators running at the same time. The values should be given in a national annex. In the absence of national values, default values are given in B.3.1;
șgnr,w,x
relevant water temperature during the considered period. A method to calculate this temperature is given in informative Annex H and in Clauses 7 and 8 of EN 15316-2-3:2007. If different heat distribution sub-systems are connected to the generator, the highest temperature among the heat distribution sub-systems or the weighted average according to the relevant annex is used for calculation.
5.4 Boiler cycling method 5.4.1
Principle of the method
This calculation method is based on the following principles. The operation time is divided in two parts: ⎯
burner on operation tON;
⎯
burner off operation (stand-by) tOFF.
The total time of operation of the generator is tgnr = tON + tOFF. Thermal losses are taken into account separately for these two periods of time. During burner on operation, the following thermal losses are taken into account: ⎯
heat of flue gas with burner on: Qch,on;
⎯
thermal losses through the generator envelope: Qge.
During burner off operation, the following thermal losses are taken into account: ⎯
heat of air flow to the chimney Qch,off;
⎯
thermal losses through the generator envelope Qge.
Auxiliary energy is considered separately for devices before and after the combustion chamber:
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EN 15316-4-1:2008 (E)
⎯
Wbr is the auxiliary energy required by components and devices that are before the combustion chamber following the energy path (typically burner fan, see Figure 6);
NOTE
⎯
Typically these components and devices are running only when the burner is on, i.e. during tON.
Wpmp is the auxiliary energy required by components and devices that are after the combustion chamber following the energy path (typically primary pump, see Figure 6).
NOTE Typically these components and devices are running during the entire operation period of the heat generator, i.e. during tgnr = tON + tOFF.
kpmp and kbr express the fractions of the auxiliary energy for these appliances recovered to the heating medium (typically the efficiency of the primary pumps and the burner fan). Therefore: ⎯
Qbr = kbr · Wbr is the auxiliary energy recovered from appliances before the heat generator;
⎯
Qpmp = kpmp · Wpmp is the auxiliary energy recovered from appliances after the heat generator.
Auxiliary energy transformed into heat and emitted to the heated space may be considered separately and is added to the recoverable thermal losses. The basic energy balance of the generation sub-system is:
QH,gen,out = Qcmb + Qbr + Qpmp − Qch,on − Qch,off − Qge
(34)
NOTE This is the same as equation (1) where:
QH,gen,ls = Qch,on + Qch,off + Qge
(35)
E H,gen,in = Qcmb
(36)
QH,gen,aux,rvd = Qbr + Qpmp
(37)
A schematic diagram of the energy balance of the generation sub-system is shown in Figure 6.
Figure 6: Energy balance diagram of generation sub-system for boiler cycling method
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EN 15316-4-1:2008 (E)
Heat losses at test conditions are expressed as a percentage (Įch,on, Įch,off and Įge) of a reference power at test conditions. The heat generator is characterised by the following values: ⎯
Φcmb
combustion power of the generator, which is the reference power for Įch,on (either design or actual value)ҏҏ;
⎯
Φref
reference power for the heat loss factors Įch,off and Įge (usually Φref = Φcmb);
⎯
Įch,on, Įch,off , Įge
⎯
Pbr
electrical power consumption of auxiliary appliances (before the generator);
⎯
kbr
recovery factor of Pbrҏ;
⎯
Ppmp
electrical power consumption of auxiliary appliances (after the generator);
⎯
kpmp
recovery factor of Ppmp;
⎯
θgnr,w,m,test average boiler water temperature at test conditions for Įch,on;
⎯
θi,brm,test
⎯
Δθge,test = θgnr,w,m,test - θi,brm,test at test conditions for Įge and Įch,off;
⎯
nch,on, nch,off, nge
heat loss factors at test conditions;
temperature of test room for Įge and Įch,off;
exponents for the correction of heat loss factors.
For multistage or modulating boilers, the following additional data is required: ⎯
Φcmb,min
minimum combustion power of the generator;
⎯
Įch,on,min
heat loss factor Įch,on at minimum combustion power Φcmb,min;
⎯
Pbr,min
electrical power consumption of auxiliary appliances (before the generator) at minimum combustion power Φcmb,min.
For condensing boilers, the following additional data is required: ⎯
ǻșwfg
temperature difference between boiler return water temperature and flue gas temperature;
⎯
XO2,fg,dry
dry flue gas oxygen contents.
For condensing multistage or modulating boilers, the following additional data is required: ⎯
ǻșwfg,min
⎯
XO2,fg,dry,min dry flue gas oxygen contents at minimum combustion power.
temperature difference between boiler return water temperature and flue gas temperature at minimum combustion power;
Actual operation conditions are characterised by the following values: ⎯
QH,gen,out
heat output to the heat distribution sub-system(s);
⎯
θgnr,w,m
average water temperature in the boiler;
⎯
θgnr,w,r
return water temperature to the boiler (for condensing boilers);
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EN 15316-4-1:2008 (E)
⎯
θi,brm
boiler room temperature;
⎯
kge,rvd
reduction factor taking into account recovery of thermal losses through the generator envelope depending on location of the generator;
⎯
ȕcmb
load factor. All powers and the load factor ȕcmb are referred to generator input (combustion power).
NOTE 1
NOTE 2 Φref is kept formally separate from Φ ҏ cmb to improve formulas clarity and to enable the use of measured data, if and when available.
Data should be declared by the manufacturer or measured, where applicable. If no declared or measured data is available, data shall be found in a relevant national annex. If no national annex is available, default values can be found in Annex D. 5.4.2
Load factor
The load factor ȕcmb is the ratio between the time with the burner on and the total time of generator operation (running and stand-by):
ȕcmb =
t ON t ON = t gnr t ON + t OFF
(38)
and also
t ON = ȕcmb ⋅ (t ON + t OFF ) = ȕcmb ⋅ t gnr
(39)
where tgnr
total time of generator operation;
tON
time with the burner on (fuel valve open, pre- and post-ventilation are not considered);
tOFF
time with the burner off.
The load factor ȕcmb shall either be calculated according to the actual energy QH,gen,out to be supplied by the generation sub-system or be measured (e.g. by time counters) on existing systems. 5.4.3 5.4.3.1
Specific thermal losses General
Specific heat losses of the generator are given at standard test conditions. Test values shall be adjusted according to actual operation conditions. This applies both to standard test values and to field measurements. 5.4.3.2
Thermal losses through the chimney with the burner on Įch,on
The correction method for this loss factor takes into account the effects of: ⎯
average water temperature in the boiler;
⎯
load factor;
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EN 15316-4-1:2008 (E)
⎯
burner settings (power and excess air changing the heat exchange efficiency).
Actual specific thermal losses through the chimney with the burner on Įch,on,corr are given by:
[
]
ch, on Įch,on,corr = Įch,on + (șgnr,w,m − șgnr,w,m,test )⋅ f corr,ch,on ⋅ ȕcmb
n
(40)
where Įch,on
heat losses through the chimney at test conditions (complement to 100 of the combustion efficiency). Įch,on is measured with the average water temperature θgnr,w,m,test. Heat losses through the chimney shall be expressed as a percentage of the combustion power Φcmb. For the design of new systems, Įch,on is the value declared by the manufacturer. For existing systems, Įch,on is given by a measure of combustion efficiency. Combustion efficiency measurement shall be realised according to national standards or recommendations. When combustion efficiency is measured, the corresponding average water temperature θgnr,w,m,test and combustion power ĭcmb shall be measured as well. If no data is available, default values are given in C.2.1, Table C.1. The source of data shall be clearly stated in the calculation report;
θgnr,w,m,test average water temperature in the boiler at test conditions (average of flow and return temperature, usually flow temperature 80 °C, return temperature 60 °C). For the design of new systems, θgnr,w,m,test is the value declared by the manufacturer. For existing systems, θgnr,w,m,test is measured together with combustion efficiency. If no data is available, default values are given in C.2.1, Table C.1. The source of data shall be clearly stated in the calculation report. For condensing boilers, return water temperature at test conditions θgnr,w,r,test shall be used in (40) instead of average water temperature θgnr,w,m,test;
θgnr,w,m
average water temperature in the boiler at actual conditions (average of flow and return temperature). For condensing boilers, return water temperature θgnr,w,r shall be used in (40) instead of average water temperature θgnr,w,m;
fcorr,ch,on
correction factor for Įch,on. Default values for this factor are given in C.2.1, Table C.1;
nch,on
exponent for the load factor ȕcmb. Default values for this exponent are given in C.2.1, Table C.2. ȕcmb raised to nch,on takes into account the reduction of losses with high intermittencies, due to a lower average temperature of the flue gas (higher efficiency at start). An increasing value of nch,on corresponds to a higher value of cmass,ch,on, defined as the specific mass of the heat exchange surface between flue gas and water per kW nominal power.
NOTE 1 Equation (40) takes into account variation in combustion efficiency depending on average temperature of water in the generator by a linear approximation. The assumption is that temperature difference between water and flue gas is approximately constant (i.e. a 20 °C increase of average water temperature causes a 20 °C increase of flue gas temperature). A 22 °C increase of flue gas temperature corresponds to 1 % increase of losses through the chimney with burner on, hence the default value 0,045 for fcorr,ch,on. Equation (40) does not include the effect of any latent heat recovery. This is done separately (see 5.4.8). NOTE 2 Equation (40) does not take into account explicitly the effect of varying air/fuel ratio. The default constant 0,045 is valid for standard excess air (XO2 = 3 % in dry flue gas). For new systems, a correct setting is assumed. For existing systems, the air/fuel ratio contributes to Įch,on. If required, the constant 0,045 may be recalculated according to the actual air/fuel ratio. NOTE 3 Equation (40) does not take into account explicitly the effect of varying combustion power ĭcmb. If the combustion power is significantly reduced, the procedure for existing systems shall be followed (i.e. Įch,on shall be measured).
37 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
5.4.3.3
Thermal losses through the generator envelope Įge
Actual specific thermal losses through the generator envelope Įge,corr are given by:
Įge,corr = Įge ⋅ k ge,rvd ⋅
(ș
(ș
gnr, w,m
gnr, w,m, test
− și,brm )
− și,brm,test )
n
ge ⋅ ȕcmb
(41)
where Įge
heat losses through the generator envelope at test conditions. Įge is expressed as a fraction of the reference power ̓Φref (usually nominal combustion power of the generator). For the design of new systems, Įge is the value declared by the manufacturer. If no data is available, default values are given in C.2.2. The source of data shall be clearly stated in the calculation report;
kge,rvd
reduction factor taking into account the location of the generator. kge,rvd takes into account recovery of thermal losses as a reduction of total losses. Default values are given in C.2.2, Table C.4;
θbrm,test
temperature of the test room. Default values are given in C.2.2, Table C.4;
θi,brm
actual temperature of the room where the generator is installed. Default values are given in C.2.2, Table C.4;
nge
exponent for the load factor ȕcmb. Default values for this exponent are given in C.2.2, Table C.5 depending on the parameter cge, defined as the ratio between the total weight of the boiler (metal + refractory materials + insulating materials) and the nominal combustion power ĭcmb of the boiler.
NOTE 1 The factor ȕcmb raised to nge takes into account the reduction of heat losses through the generator envelope if the generator is allowed to cool down during stand-by. This reduction applies only to the specific control option, where the room thermostat stops directly the burner and the circulation pump (in series with the boiler thermostat, solution adopted on small systems only). In all other cases nge = 0 inhibits this correction. NOTE 2 It is assumed that heat losses through the envelope are related to the temperature difference between the average water temperature in the boiler and the temperature of the boiler surroundings. The relation is assumed to be linear (heat conduction through the boiler insulation). NOTE 3 Įge can be determined as the difference between the combustion efficiency and the net efficiency of the generator at test conditions (continuous operation).
Recovery of thermal losses through the generator envelope is taken into account as a reduction of total losses (by the reduction factor kge,rvd). As an alternative, it is possible to determine the actual total generator envelope thermal losses Įge,corr from the total heat losses at test conditions Įge by:
Įge,corr = Įge ⋅
(ș
(ș
gnr, w,m
gnr, w,m, test
− și,brm )
− și,brm,test )
n
ge ⋅ ȕcmb
(42)
and determine the actual recoverable thermal losses factor, Įge,rbl by:
Įge,rbl = Įge,corr ⋅ (1 − k ge,rvd )
(43)
38 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
5.4.3.4
Thermal losses through the chimney with the burner off Įch,off
This thermal loss takes into account the stack effect of the chimney, which causes a flow of cold air through the boiler when the burner is off. A correction according to the average water temperature in the boiler and the boiler room temperature is required. A second correction is required when the room thermostat shuts down the circulation pump at the same time as the burner. With this control option, the actual average temperature of the water in the boiler decreases with the load factor. During each burner off period, the maximum energy which can be lost is the heat stored in the boiler (in the metallic parts and in the water). Therefore, the load factor is a function of the heat capacity of the boiler. Actual specific thermal losses through the chimney when the burner is off Įch,off,corr are given by:
Įch,off,corr = Įch,off ⋅
(ș
(ș
gnr,w,m
gnr, w,m,test
− și,brm )
− și,brm,test )
ch, of ⋅ ȕcmb
n
(44)
where Įch,off
heat losses through the chimney when the burner is off at test conditions. Įch,off is expressed as a percentage of the reference power Φ ҏ ref (usually nominal combustion power of the generator). For the design of new systems, Įch,off is the value declared by the manufacturer. For existing systems, Įch,off can be calculated by measuring the flow rate and the temperature at the boiler flue gas outlet. If no data is available, default values are given in C.2.3, Table C.6. The source of data shall be clearly stated in the calculation report;
nch,off
exponent for the load factor ȕcmb. Default values for this exponent are given in C.2.3, Table C.7 depending on the parameter cch,off, defined as the ratio between the total weight of the boiler (metal + refractory materials + insulating materials) and the nominal combustion power Φcmb of the boiler.
NOTE The factor ȕcmb raised to nch,off takes into account the reduction of heat losses through the chimney with the burner off if the generator is allowed to cool down during stand-by. This reduction applies only to the specific control option, where the room thermostat stops directly the burner and the circulation pump (in series with the boiler thermostat, solution adopted on small systems only). In all other cases nch,off = 0 inhibits this correction.
5.4.4
Total thermal losses
Thermal losses through the chimney with the burner on Qch,on are given by:
Qch,on =
Įch,on,corr 100
⋅ ĭcmb ⋅ t ON
(45)
Thermal losses through the chimney with the burner off Qch,off are given by:
Qch,off =
Įch,off,corr 100
⋅ ĭref ⋅ t OFF
(46)
Thermal losses through the generator envelope Qge are given by:
Qge =
Įge,corr 100
⋅ ĭref ⋅ (t OFF + t ON )
(47)
39 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
5.4.5
Auxiliary energy
For each auxiliary device i of the generator, the following data shall be determined: ⎯
Electrical power consumption Pi. Values can be: ⎯
declared by the manufacturer;
⎯
measured;
⎯
or default values calculated according to C.3.
The source of data shall be clearly stated in the calculation report. ⎯
Running time ton,i, as a function of load factor ȕcmb where appropriate (i.e. burner auxiliaries).
EXAMPLE 1
⎯
Part of the electrical energy converted to heat and recovered to the system before the combustion chamber kbr,i (auxiliary energy recovery factor). The default value for kbr is given in C.3, Table C.9.
EXAMPLE 2
⎯
Burner fan: ton = ȕcmb · tgnr
Examples of such auxiliaries are combustion air fan, fuel pump, fuel heaters.
Part of the electrical energy converted to heat and recovered to the system after the generator kpmp,i (auxiliary energy recovery factor). The default value for kpmp is given in C3, Table C.9.
EXAMPLE 3
Examples of such auxiliaries are primary pumps.
Variable electrical power consumption should be approximated by an equivalent constant average electrical power consumption. The total auxiliary energy required by the generation sub-system WH,gen,aux is given by:
WH,gen,aux = ¦i Pgnr,aux,i ⋅ t on,i
(48)
The auxiliary energy of devices j before the combustion chamber (i.e. combustion air fan, fuel heater, etc.) which is converted to heat and recovered, is given by:
Qbr = ¦ jPbr, j ⋅ t on, j ⋅ k br
(49)
If ton,j = ton for all devices j and assuming Pbr = ȈPbr,j:
Qbr = P br ⋅k br ⋅ t ON NOTE
(50)
tON = tgnr · ȕcmb
The auxiliary energy of devices k after the combustion chamber (i.e. primary pump) which is converted to heat and recovered to the system is given by:
Qpmp = ¦k Ppmp,k ⋅ t on,k ⋅ k pmp
(51)
If ton,k = tgnr for all devices k and assuming Ppmp = ȈPpmp,k:
Qpmp = Ppmp ⋅ k pmp ⋅ t gnr
(52)
40 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
The total auxiliary energy required by the generation sub-system WH,gen,aux is given by:
WH,gen,aux = 5.4.6
Qbr Qpmp + k br k pmp
(53)
Calculation procedure for single stage generators
a) Determine the total heat output QH,gen,out of the generation sub-system, which is equal to QH,dis,in, total heat to be supplied to the distribution sub-system in the calculation period. For multiple interconnected distribution and/or generation sub-systems, refer to 4.6 and 5.4.9 and then proceed with the present procedure using QH,gen,out,i for each generator. b) Determine the total time tgnr of operation of the generator (tgnr = tON + tOFF). c) Set the load factor ȕcmb = 1. The calculation requires iterations with the load factor ȕcmb approaching the final value. If the value of ȕcmb is known (measured on an existing system), perform step d) and e), skip step f) and g) and proceed to step h) (no iteration required). d) Determine the values of Įch,on,corr, Įch,off,corr and Įge,corr according to 5.4.3 for the current load factor ȕcmb. e) Determine the values of Qpmp, Qbr and WH,gen,aux according to 5.4.5 for the current load factor ȕcmb. f)
Calculate a new load factor ȕcmb by:
100 ⋅
ȕcmb
QH,gen,out − Qpmp
+ Įch,off,corr + Įge,corr t gnr ⋅ ĭref = ĭ +k ⋅P ĭ 100 ⋅ cmb br br − cmb ⋅ Įch,on,corr + Įch,off,corr ĭref ĭref
(54)
g) Repeat steps d), e) and f) until ȕcmb converges. Typically one iteration is enough. More iterations may be required if ȕcmb approaches 0. h) Calculate the energy to be supplied by the fuel by:
EH,gen,in = ĭcmb ⋅ t gnr ⋅ ȕcmb i)
(55)
Calculate the total thermal losses by:
QH,gen,ls = EH,gen,in − QH,gen,out + Qbr + Qpmp
(56)
There are no recoverable thermal losses, since heat recovery has been taken into account as a reduction of thermal losses through the generator envelope:
QH,gen,ls,rbl = 0 5.4.7 5.4.7.1
(57)
Multistage and modulating generators General
A multistage or modulating generator is characterised by 3 possible states:
41 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
⎯
burner off;
⎯
burner on at minimum power;
⎯
burner on at maximum power.
It is assumed that only two situations are possible: ⎯
the generator is operating intermittently as a single stage generator at minimum power;
⎯
the generator is operating at a constant average power between minimum and maximum power.
5.4.7.2
Additional data required
The following additional data are required to characterise a multistage or modulating generator:ҏ ⎯
Φcmb,min
minimum combustion power of the generator;
⎯
Įch,on,min
heat loss factor Įch,on at minimum combustion powerҏ Φcmb,minҏ, as a fraction of Φcmb,min;
⎯
Pbr,min
electrical power consumption of burner auxiliaries at minimum combustion power.
If data from the manufacturer or default values from a national annex are not available, default values are calculated according to C.4. It is assumed that nominal values correspond to maximum power output, therefore: ⎯
Φcmb,max = Φcmb maximum combustion power of the generator;
⎯
Įch,on,max = Įch,on heat loss factor at maximum combustion powerҏ Φcmb,max.
5.4.7.3
Calculation procedure for multistage or modulating generators
The procedure begins following the method described in 5.4.6 for single stage generators, using: ⎯
Φ ҏ cmb; ҏ cmb,min instead of Φ
⎯
Įch,on,min instead of Įch,on;
⎯
θgnr,w,test,min instead of θgnr,w,test;
⎯
ҏPbr,min instead of ҏPbr.
If the load factor ȕcmb converges to a value which is not greater than 1, the procedure for single stage generators is followed up to the end. If the load factor ȕcmb converges to a value greater than 1, then tON = tgnr and the average combustion power
Φcmb,avg is calculated as follows:
a) Determine the total heat output QH,gen,out of the generation sub-system, which is equal to QH,dis,in, total heat to be supplied to the distribution sub-system in the calculation period. For multiple interconnected distribution and/or generation sub-systems, refer to 4.6 and 5.4.9 and then proceed with the present procedure using QH,gen,out,i for each generator. b) Calculate Įge,corr according to equation (41) and load factor ȕcmb = 1. c) Calculate Įch,on,min,corr and Įch,on,max,corr according to equation (40) and load factor ȕcmb = 1.
42 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
d) Calculate Qbr and Qbr,min according to equation (50) using Pbr, Pbr,min and ȕcmb = 1. ҏ cmb. e) Set ҏΦcmb,avg = Φ f)
Calculate Įch,on,avg,corr by:
Įch,on,avg,corr = Įch,on,min,corr + (Įch,on,max,corr − Įch,on,min,corr ) ⋅
ĭcmb,avg − ĭcmb,min ĭcmb,max − ĭcmb,min
(58)
g) Calculate ҏQbr,avg by:
Qbr,avg = Qbr,min + (Qbr,max − Qbr,min ) ⋅
ĭcmb,avg − ĭcmb,min ĭcmb,max − ĭcmb,min
(59)
h) Calculate a new Φ ҏ cmb,avg by:
QH,gen,out − Qpmp − Qbr,avg t gnr
ĭcmb,avg =
1−
+
Įge,corr 100
⋅ ĭref
Įch,on,avg,corr
(60)
100
i)
Repeat steps f), g) and h) until ҏΦcmb,avg converges. Typically one iteration is enough.
j)
Calculate the energy to be supplied by the fuel by:
E H,gen,in = ĭcmb,avg ⋅ t gnr
(61)
k) Calculate average power of auxiliaries before the combustion chamber ĭbr,avg by:
ĭbr,avg = ĭbr,min + (ĭbr,max − ĭbr,min ) ⋅ l)
ĭcmb,avg − ĭcmb,min ĭcmb,max − ĭcmb,min
(62)
Calculate auxiliary energy by:
WH,gen,aux = t gnr ⋅ (ĭbr,avg + ĭpmp )
(63)
m) Calculate recovered auxiliary energy by:
WH,gen,aux,rvd = t gnr ⋅ (ĭbr,avg ⋅ k br + ĭpmp ⋅ k pmp )
(64)
n) Calculate total thermal losses by:
QH,gen,ls = EH,gen,in − QH,gen,out + WH,gen,aux,rvd
(65)
There are no recoverable thermal losses, since recovery has been taken into account as a reduction of thermal losses through the generator envelope:
QH,gen,ls,rbl = 0
(66)
43 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
5.4.8
Condensing boilers
5.4.8.1
Principle of the method
The effect of recovery of latent heat of condensation is taken into account as a reduction of Įch,on (losses through the chimney with burner on). Recovery of latent heat of condensation is calculated taking into account flue gas temperature and excess air. The connection between return water temperature and flue gas temperature is given by the ǻșwfg between flue gas and return water, which characterises the boiler. For multistage boilers, ǻșwfg and excess air are specified separately for minimum and maximum combustion power. For modulating boilers, it is assumed that ǻșwfg and oxygen contents XO2,fg,dry (excess air) vary linearly between maximum and minimum combustion power. 5.4.8.2
Boiler data
To characterise a single stage (on-off) condensing boiler, the following additional data is required: ⎯
ǻșwfg
temperature difference between boiler return water temperature and flue gas temperature. Value should be given by the appliance manufacturer. If this data is not available, it can be either measured on existing system or taken from tables in a national annex. If such information is missing, default values are given in C.5, Table C.14;
⎯
XO2,fg,dry
flue gas oxygen contents. Value shall be given by the appliance manufacturer. If this data is not available, it can be either measured on existing systems or taken from tables in a national annex. If such information is missing, default values are given in C.5, Table C.14.
For multistage or modulating burners, the following additional data is required: ⎯
ǻșwfg,min
⎯
XO2,fg,dry,min flue gas oxygen contents at minimum combustion power ĭcmb,min . Value shall be given by the appliance manufacturer. If this data is not available, it can be either measured on existing system or taken from tables in a national annex. If such information is missing, default values are given in C.5, Table C.14;
⎯
ǻșwfg,max
⎯
XO2,fg,dry,max flue gas oxygen contents at maximum combustion power instead of XO2,fg,dry. Value shall be given by the appliance manufacturer. If this data is not available, it can be either measured on existing system or taken from tables in a national annex. If such information is missing, default values are given in C.5, Table C.14.
NOTE
temperature difference between boiler return water temperature and flue gas temperature at minimum combustion power. ǻșwfg,min shall be given by the appliance manufacturer. If this data is not available, it can be either measured on existing system or taken from tables in a national annex. If such information is missing, default values are given in C.5, Table C.14;
temperature difference between boiler return water temperature and flue gas temperature at maximum combustion power instead of ǻșwfg. ǻșwfg,max shall be given by the appliance manufacturer. If this data is not available, it can be either measured on existing system or taken from tables in a national annex. If such information is missing, default values are given in C.5, Table C.14;
ǻșwfg,max and XO2,fg,dry,max are the same values as ǻșwfg and XO2,fg,dry for single stage boilers.
44 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
5.4.8.3
Data on fuel
The following data on fuel is required for calculation of recovery of latent heat of condensation: ⎯
Hs
Gross calorific value of the fuel unit;
⎯
Hi
Net calorific value of the fuel unit;
⎯
Vair,st,dry
Stoichiometric dry air as standard volume per unit of fuel ([Nm³/kg] or [Nm³/Nm³]);
⎯
Vfg,st,dry
Stoichiometric dry flue gas as standard volume per unit of fuel ([Nm³/kg] or [Nm³/Nm³]);
⎯
mH2O,st
Stoichiometric water production per unit of fuel ([kg/kg] or [kg/Nm³]).
Data should be given in a national annex. If no national annex is available, default data is given in C.5, Table C.13. 5.4.8.4
Single stage (on-off) boilers
Condensing, single stage, boiler fuel energy, auxiliary energy and thermal losses shall be calculated with the same procedure as in 5.4.6 where Įch,on,corr is replaced by Įch,on,cond given by: Įch,on,cond = Įch,on,corr – Įcond
(67)
where ⎯
recovered latent heat of condensation at nominal power, as a percentage of Φcmb, calculated according to 5.4.8.7.
Įcond
5.4.8.5
Multi stage (stepping) boilers
The procedure set out in 5.4.7 shall be followed, where Įch,on,max,corr and Įch,on,min,corr are replaced by Įch,on,max,cond and Įch,on,min,cond given by: Įch,on,max,cond = Įch,on,max,corr –Įcond,max
(68)
Įch,on,min,cond = Įch,on,min,corr – Įcond,min
(69)
where ⎯
Įcond,min
⎯
Įcond,max
recovered latent heat of condensation at minimum combustion power, as a percentage of Φcmb,min; recovered latent heat of condensation at maximum combustion power, as a percentage of
Φcmb,max.
Įcond,min is calculated according to 5.4.8.7 using: ⎯
XO2,fg,dry,min instead of XO2,fg,dry;
⎯
ǻșwfg,min instead of ǻșwfg.
Įcond,max is calculated according to 5.4.8.7 using: ⎯
XO2,fg,dry,max instead of XO2,fg,dry;
⎯
ǻșwfg,max instead of ǻșwfg.
45 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
5.4.8.6
Modulating boilers
The procedure set out in 5.4.7 shall be followed, where Įch,on,min,corr is replaced by Įch,on,min,cond given by: Įch,on,min,cond = Įch,on,min,corr – Įcond,min
(70)
and Įch,on,avg is replaced by Įch,on,avg,cond given by: Įch,on,avg,cond = Įch,on,avg,corr – Įcond,avg
(71)
where ⎯
Įcond,min recovered latent heat of condensation at minimum combustion power, as a percentage of Φcmb,min;
⎯
Įcond,avg recovered latent heat of condensation at average combustion power, as a percentage of Φcmb,avg.
Įcond,min is calculated according to 5.4.8.7 using: ⎯
XO2,fg,dry,min instead of XO2,fg,dry;
⎯
ǻșwfg,min instead of ǻșwfg.
Įcond,avg is calculated according to 5.4.8.7 using: ⎯
XO2,fg,dry,avg instead of XO2,fg,dry;
⎯
ǻșwfg,avg instead of ǻșwfg.
ǻșwfg,avg is calculated (linear interpolation of ǻșwfg according to combustion power) by:
ǻșwfg,avg = ǻșwfg,min + (ǻșwfg,max − ǻșwfg,min )⋅
ĭcmb,avg − ĭcmb,min ĭcmb,max − ĭcmb,min
(72)
XO2,fg,dry,avg is calculated (linear interpolation of XO2,fg,dry according to combustion power) by:
X O2,fg,dry,avg = X O2,fg,dry,min + (X O2,fg,dry,max − X O2,fg,dry,min ) ⋅ 5.4.8.7
ĭcmb,avg − ĭcmb,min ĭcmb,max − ĭcmb,min
(73)
Calculation procedure of Įcond
NOTE Įch,on,cond may be negative when values are based on fuel net calorific value. Total losses will always be positive when referred to gross calorific values according to 4.7.
Flue gas temperature (at boiler outlet connection to flue gas) is calculated by:
șfg = șgnr,w,r + ǻș wfg
(74)
where
θgnr,w,r
boiler return water temperature, calculated according to Annex H.
46 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
Combustion air temperature θair is assumed either equal to installation room temperature for type B appliances or to external air temperature for type C appliances. Actual amount of dry flue gas Vfg,dry is calculated by:
Vfg,dry = Vfg,st,dry ⋅
20,94 20,94 − X O2,fg,dry
(75)
Actual amount of dry combustion air Vair,dry is calculated by: Vair,dry = Vair,st,dry + Vfg,dry – Vfg,st,dry NOTE
(76)
Vfg,dry – Vfg,st,dry is excess air.
Saturation humidity of air mH2O,air,sat and flue gas mH2O,fg,sat shall be calculated according to θair (combustion air temperature) and θfg (flue gas temperature) respectively and expressed as kg of humidity per Nm³ of dry air or dry flue gas. Data can be found in the following Table 3. Linear or polynomial interpolation shall be used for intermediate temperatures. Table 3 – Saturation humidity as a function of temperature Temperature °C
(θair or θfg)
0
Saturation humidity kg/Nm³dry 0,00493 mH2O,air,sat or mH2O,fg,sat NOTE
10
20
30
40
0,00986
0,01912
0,03521
0,06331
50
0,1112
60
0,1975
70
0,3596
Saturation humidity is expressed as kg of water vapour per Nm³ of dry gas (either air or flue gas).
Total humidity of combustion air mH2O,air is calculated by:
mH2O,air = mH2O,air,sat ⋅ Vair,dry ⋅
xair 100
(77)
where ⎯
xair combustion air relative humidity. Default value is given in C.5, Table C.14.
Total humidity of flue gas mH2O,fg is calculated by:
mH2O,fg = mH2O,fg,sat ⋅ Vfg,dry ⋅
xfg
100
(78)
where ⎯
xfg flue gas relative humidity. Default value is given in C.5, Table C.14.
The amount of condensing water mH2O,cond is calculated by: mH2O,cond = mH2O,st + mH2O,air - mH2O,fg
(79)
If mH2O,cond is negative, there is no condensation. Then mH2O,cond = 0 and Įcond = 0. The specific latent heat of condensation hcond,fg is calculated by:
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hcond,fg = 2 500 600 J/kg – θfg x 2 435 J/kg·°C
(80)
hcond,fg = 694,61 Wh/kg – θfg x 0,676 4 Wh/kg·°C
(81)
or
NOTE
Use equation (80) or (81) according to the choice of units for energy and time.
The condensation heat Qcond is calculated with: Qcond = mH2O,cond · hcond.fg
(82)
If the calculation is based on net calorific values, then the recovered latent heat of condensation Įcond is calculated by:
α cond = 100 ⋅
Qcond Hi
(83)
If the calculation is based on gross calorific values, then the recovered latent heat of condensation Įcond is calculated by:
α cond = 100 ⋅ NOTE
5.4.9 5.4.9.1
Qcond Hs
(84)
Default values in Annex C are based on net calorific values.
Systems with multiple generators General
In general, sub-systems with multiple generators can be calculated as separated generation sub-systems in parallel. Criteria similar to those given in 5.3.3 can be used to split QH,gen,out amongst available generators. 5.4.9.2
Modular systems
A modular system consists of Ngnr identical modules or generators, each characterized by a maximum and a minimum combustion power Φcmb,i,max and Φcmb,i,min, assembled as a single unit or connected to the same mains. The combustion power of the entire system is calculated by:
Φcmb = Φcmb,i,max · Ngnr 5.4.9.3
(85)
Modular systems with hydraulic shutdown of stand-by modules
If there is an automatic control system applied, which shuts down and insulates stand-by generators and/or modules from the distribution network, the following procedure shall be followed. The number Ngnr,on of running generators and/or modules is calculated as:
N gnr,on = int (N gnr ⋅ ȕcmb + 1)
(86)
where the load factor ȕcmb is calculated for a single stage generator of combustion power Φcmb.
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EN 15316-4-1:2008 (E)
The actual performance of the modulating generator is calculated following the procedure for multistage generators and assuming: ⎯
Φcmb,max = Φcmb,i,max · Ngnr,on
⎯
Φcmb,min = Φcmb,i,min
5.4.9.4
Modular systems without hydraulic shutdown of stand-by modules
If there is no control system applied, which shuts down and insulates stand-by generators and/or modules from the distribution network, the following procedure shall be followed. The actual performance of the modulating generator is calculated following the procedure for multistage generators and assuming: ⎯
Φcmb,max = Φcmb,i,max · Ntot;
⎯
Φcmb,min = Φcmb,i,min · Ntot.
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EN 15316-4-1:2008 (E)
Annex A (informative) Sample seasonal boiler performance method based on system typology (typology method)
A.1
Scope
This Annex is an example of a national annex defining a typology method. The example is based on the Seasonal efficiency calculation procedure (SEDB_UK) intended for use in the housing sector of the UK. If there is no such appropriate national annex, this method (system typology) cannot be used.
A.2
Limitations in use of this method
This procedure is used to determine the seasonal efficiency of gas and oil boilers installed in the UK housing sector. It is named SEDB_UK (Seasonal Efficiency of Domestic Boilers in the UK). This method of calculation is applicable only to boilers for which the full load efficiency and the 30 % part load efficiency values, obtained by the methods deemed to satisfy Council Directive 92/42/EEC about Boiler Efficiency [1], are available. These are net efficiency values (higher efficiency values, referenced to the lower heat value of fuels). It is essential that both test results are available and that the tests are appropriate to the type of boiler as defined in Council Directive 92/42/EEC about Boiler Efficiency [1], otherwise the calculation cannot proceed. If SEDB_UK values are declared, they should be accompanied by the wording given in A.5, which is necessary to avoid confusion with efficiency values calculated by other methods.
A.3
Boiler typologies definition
For the purpose of this method, the following boiler typologies are defined. regular boiler boiler which does not have the capability to provide domestic hot water directly (i.e. not a combination boiler). It may nevertheless provide domestic hot water indirectly via a separate hot water storage cylinder combination boiler boiler with the ability to provide domestic hot water directly, in some cases containing an internal hot water store instantaneous combination boiler combination boiler without an internal hot water store, or with an internal hot water store of capacity less than 15 litres storage combination boiler combination boiler with an internal hot water store of capacity at least 15 litres but less than 70 litres, or a combination boiler with an internal hot water store of capacity at least 70 litres, in which the feed to the space
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EN 15316-4-1:2008 (E)
heating circuit is not taken directly from the store. If the store is at least 70 litres and the feed to the space heating circuit is taken directly from the store, refer to definition of combined primary storage unit (CPSU) combined primary storage unit (CPSU) single appliance designed to provide both space heating and domestic hot water, in which there is a burner that heats a thermal store which contains mainly primary water which is in common with the space heating circuit. Capacity of the hot water store is at least 70 litres and the feed to the space heating circuit is taken directly from the store on/off boiler boiler without the capability to vary the fuel burning rate whilst maintaining continuous burner firing. This includes boilers with alternative burning rates set once only at the time of installation, referred to as range rating modulating boiler boiler with the capability to vary the fuel burning rate whilst maintaining continuous burner firing condensing boiler boiler designed to make use of the latent heat released by condensation of water vapour in the combustion flue products. The boiler must allow the condensate to leave the heat exchanger in liquid form by way of a condensate drain. Boilers not so designed, or without the means to remove the condensate in liquid form are called ‘non-condensing’
A.4
Procedure
In the procedure, the data are first converted to gross efficiency (lower efficiency values, referenced to the higher heat value of fuels) under test conditions, and then converted to a seasonal efficiency, which applies under typical conditions of use in a dwelling, allowing for standing losses. In this Annex, efficiencies are expressed in percent. Intermediate calculations should be done to at least four decimal places of a percentage, and the final result should be rounded off to one decimal place. The steps are as follows: a) Determine fuel for boiler type. The fuel for boiler type must be one of natural gas, LPG (butane or propane) or oil (kerosene or gas oil). b) Obtain test data. Retrieve the full-load net efficiency ȘPn,net and 30 % part-load net efficiency ȘPint,net test results. Tests must have been carried out using the same fuel as the fuel for boiler type. c) Reduce to maximum net efficiency values ȘPn,net,max and ȘPint,net,max. Table A.1 gives the maximum values of net efficiency depending on the type of boiler. Reduce any higher net efficiency test values to the appropriate value given in Table A.1. Table A.1 – Maximum net efficiency values Efficiency at full load ȘPn,net,max %
Efficiency at 30 % load ȘPint,net,max %
Condensing boilers
101,0
107,0
Non-condensing boilers
92,0
91,0
Boiler type
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d) Convert the full load efficiency and the 30 % part load efficiency from net values to gross values. Use the following equation (A1) with the appropriate factor from Table A.2.
η Px,gross = f ntg ⋅ ȘPx,net
(A1)
Table A.2 – Efficiency conversion factors Fuel
Net-to-gross conversion factor fntg
Natural gas
0,901
LPG (propane or butane)
0,921
Oil (kerosene or gas oil)
0,937
e) Categorise the boiler. i)
Select the appropriate category for the boiler according to the definitions (see A.3).
ii)
For a gas or LPG boiler, determine whether or not it has a permanent pilot light:
iii)
⎯
if it has a permanent pilot light, set fplt = 1;
⎯
if not, set fplt = 0.
For a storage combination boiler (either on/off or modulating), determine from the test report whether or not the losses from the store are included in the test values reported (this depends on whether or not the store was connected to the boiler during the tests): ⎯ if the store loss is included, set fsto = 1; ⎯ if not, set fsto = 0.
iv) For a condensing combined primary storage unit (CPSU, either on/off or modulating), ⎯ set fsto = 1. v)
For a storage combination boiler or a CPSU, obtain the store volume, Vsto, in litres from the specification of the device and the stand-by loss factor Hsby, using the following equations: ⎯ if dins,sto < 10 mm then Hsby = 0,0945 – 0,0055 x dins,sto; ⎯ if dins,sto ≥ 10 mm then Hsby = 0,394 / dins,sto; where dins,sto is the thickness of the insulation of the store in mm.
f)
Calculate seasonal efficiency. i)
Use the boiler category and other characteristics as defined in A.3 (non-condensing or condensing, gas or LPG or oil, on/off or modulating) to look up the appropriate SEDB_UK equation number in Table A.3 and select the appropriate equation from Table A.4 or Table A.5, as applicable. If no equation number is given in Table A.3, the calculation cannot proceed.
ii)
Substitute the gross full load efficiency ȘPn,gross and part load efficiency ȘPint,gross (found in step 4) and fplt, fsto, Vsto and Hsby (found in step 5) in the equation found in step 6i. Round off the result to one decimal place, i.e. to the nearest 0,1 %. Note the result for the purpose of the declaration in A.5.
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EN 15316-4-1:2008 (E)
iii)
Convert the gross seasonal efficiency back to net seasonal efficiency using:
η Px,net =
1 ⋅ ȘPx,gross f ntg
(A2)
Low-temperature
Gas or LPG
On/off
Modulating
On/off
Modulating
On/off
Modulating
On/off
Modulating
Table A.3 – Equation numbers for different boiler types
Regular boiler
101
102
201
X
X
101
102
201
X
Istantaneous combi boiler
103
104
202
X
X
103
104
202
X
Storage combi boiler
105
106
203
X
X
105
106
203
X
107
107
X
X
X
105
106
X
X
Non-condensing
Gas or LPG
Oil
Condensing
Oil
Boiler type
Combined unit
primary
storage
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EN 15316-4-1:2008 (E)
Table A.4 – Seasonal efficiency calculation equations Șgen for natural gas boilers and LPG boilers Gas or LPG boiler type
Eq. no.
Equation
§ ȘPn,gross + ȘPint,gross · ¸¸ − 2,5 − 4 ⋅ f plt 2 © ¹
η gen,gross = ¨¨
On/off regular
101
Modulating regular
102
η gen,gross = ¨¨
On/off instantaneous combination
103
η gen,gross = ¨¨
Modulating instantaneous combination
104
η gen,gross = ¨¨
105
η gen,gross = ¨¨
106
η gen,gross = ¨¨
107
η gen,gross = ¨¨
On/off storage combination On/off combined primary storage unit (condensing only) Modulating storage combination Modulating combined primary storage unit (condensing only) On/off combined primary storage unit (non-condensing only) Modulating combined primary storage unit (non-condensing only)
§ ȘPn,gross + ȘPint,gross · ¸¸ − 2,0 − 4 ⋅ f plt 2 ¹ © § ȘPn,gross + ȘPint,gross · ¸¸ − 2,8 − 4 ⋅ f plt 2 © ¹
§ ȘPn,gross + ȘPint,gross · ¸¸ − 2,1 − 4 ⋅ f plt 2 © ¹
§ ȘPn,gross + ȘPint,gross 2 ©
· ¸¸ − 2,8 + (0,209 ⋅ f sto ⋅ H sby ⋅ Vsto ) − 4 ⋅ f plt ¹
§ ȘPn,gross + ȘPint,gross 2 ©
· ¸¸ − 1,7 + (0,209 ⋅ f sto ⋅ H sby ⋅ Vsto ) − 4 ⋅ f plt ¹
§ ȘPn,gross + ȘPint,gross 2 ©
· ¸¸ − (0,539 ⋅ H sby ⋅ Vsto ) − 4 ⋅ f plt ¹
Table A.5 – Seasonal efficiency calculation equations Șgen for oil boilers Oil boiler type
Eq. No.
Equation
§ ȘPn,gross + ȘPint,gross · ¸¸ 2 © ¹
Regular
201
η gen,gross = ¨¨
Instantaneous combination
202
η gen,gross = ¨¨
Storage combination
203
η gen,gross = ¨¨
§ ȘPn,gross + ȘPint,gross · ¸¸ − 2,8 2 © ¹
§ ȘPn,gross + ȘPint,gross 2 ©
· ¸¸ − 2,8 + (0,209 ⋅ f sto ⋅ H sby ⋅ Vsto ) ¹
g) Calculate generation thermal loss. The SEDB_UK method is based on a typological approach using correlations on efficiency values. Therefore it is necessary to express the seasonal performance of generation in absolute values in order to fit the general structure of EN 15316.
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The total generation thermal loss QH,gen,ls is calculated by:
QH,gen,ls = QH,gen,out ⋅
1 − Șgen,net Șgen,net
(A3)
h) Calculate fuel heat requirement. The fuel heat requirement EH,gen,in is calculated by:
EH,gen,in = i)
QH,gen,out Șgen,net
(A4)
Calculate auxiliary energy WH,gen,aux. The auxiliary energy is calculated according to 5.3.6.
j)
Calculate total recoverable thermal loss. No recoverable generation thermal loss is taken into account.
A.5
Declaring values of seasonal efficiency a) Manufacturers wishing to declare the seasonal efficiency of their products as SEDB_UK values can do so provided that: i)
they use the SEDB_UK calculation procedure given in A.2 above;
ii)
and the necessary boiler test data are independently certified.
b) Where a manufacturer declares the SEDB_UK, it shall be expressed as: “Seasonal Efficiency (SEDB_UK) = [x] % The test data from which it has been calculated have been certified by [insert name and/or identification of Notified Body].” Data for several products may be presented in tabulated form, in which case the second paragraph of the declaration should be incorporated as a note to the table.
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EN 15316-4-1:2008 (E)
Annex B (informative) Additional formulas and default values for parametering the case specific boiler efficiency method
B.1
Information on the method
B.1.1
Basic assumptions and intended use
This method is intended for use with boilers where data declared according to Council Directive 92/42/EEC [1] are known. This methodology assumes that losses power and auxiliary power are linearly dependant on boiler load in two ranges: ⎯
from 0 to intermediate power;
⎯
from intermediate power to nominal (maximum) load.
The intermediate load is assumed to be the same as defined by Council Directive 92/42/EEC on Boiler Efficiency [1], that is 30 % of maximum load. It is also assumed that efficiencies determined according to testing standards can be corrected using linear functions of the actual boiler operating temperature or boiler installation room temperature.
B.1.2
Known approximations
The intermediate power should be the minimum power with burner on. The intermediate load of 30 % is kept to facilitate use of data declared according to Council Directive 92/42/EEC. Polynomial interpolation may be used to reduce the influence of this approximation. The assumption of the linear dependence of efficiencies according to boiler temperature is not true when condensation (which is inherently a non linear phenomenon) occurs. Variable values of fcorr according to boiler typology have been introduced to reduce the influence of this approximation. The influence of installation room temperature on boiler efficiency at 30 % and 100 % load is neglected. Installation room temperature has an influence only on stand-by losses and therefore on performance in the range from 0 to intermediate load.
B.2
Polynomial interpolation formulas
The following equation may replace linear interpolation equations (20) and (21): 2 ⋅ ĭgnr,ls,Px = ĭgnr,ls,P0,corr + ĭPx
2 + ĭPx ⋅ ĭPn ⋅
ĭPint ⋅ (ĭgnr,ls,Pn,corr − ĭgnr,ls,P0,corr ) − ĭPn ⋅ (ĭgnr,ls,Pint,corr − ĭgnr,ls,P0,corr ) ĭPn ⋅ ĭPint ⋅ ( ĭPn − ĭPint )
2 (ĭgnr,ls,Pint,corr − ĭgnr,ls,P0,corr ) − ĭPint ⋅ (ĭgnr,ls,Pn,corr − ĭgnr,ls,P0,corr )
ĭPn ⋅ ĭPint ⋅ ( ĭPn − ĭPint )
+
(B1)
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EN 15316-4-1:2008 (E)
B.3
Generator efficiencies and stand-by losses
B.3.1
Default values for generator efficiency at full load and intermediate load as a function of the generator power output
The generator efficiency at full load and intermediate load as a function of the generator power output is given by:
§ ĭPn,ltd · ¸¸ © 1000 W ¹
η gnr,Pn = c1 + c2 ⋅ log¨¨
(B2)
The generator efficiency at intermediate load as a function of the generator power output is given by:
§ ĭ Pn, ltd · ¸¸ © 1 000 W ¹
η gnr, Pint = c3 + c 4 ⋅ log ¨¨
(B3)
The generator efficiency at intermediate load for oil-condensing boilers as a function of the generator power output is given by:
η gnr,Pint
· § ĭ c3 + c4 ⋅ log¨¨ Pn,ltd ¸¸ © 1000 W ¹ = 1,05
(B4)
where ⎯
ɎPn,ltd
⎯
c1, c2, c3, c4 coefficients given in Table B.1.
nominal power output, limited to a maximum value of 400 kW. If the nominal power output of the generator is higher than 400 kW, then the value of 400 kW is adopted in equations (B2), (B3) and (B4);
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EN 15316-4-1:2008 (E)
Table B.1 – Parameters for calculation of generator efficiency and temperature limitation Build year
c1 %
c2 %
c3 %
c4 %
șgnr,w,min °C
before 1978
77,0
2,0
70,0
3,0
50 °C
1978 to 1987
79,0
2,0
74,0
3,0
50 °C
before 1978
78,0
2,0
72,0
3,0
50 °C
1978 to 1994
80,0
2,0
75,0
3,0
50 °C
after 1994
81,0
2,0
77,0
3,0
50 °C
before 1978
79,5
2,0
76,0
3,0
50 °C
1978 to 1994
82,5
2,0
78,0
3,0
50 °C
after 1994
85,0
2,0
81,5
3,0
50 °C
before 1978
80,0
2,0
75,0
3,0
50 °C
Heating boiler with forced draught 1978 to 1986 burner 1987 to 1994
82,0
2,0
77,5
3,0
50 °C
84,0
2,0
80,0
3,0
50 °C
85,0
2,0
81,5
3,0
50 °C
82,5
2,0
78,0
3,0
50 °C
84,0
2,0
80,0
3,0
50 °C
1978 to 1994
85,5
1,5
86,0
1,5
35 °C
after 1994
88,5
1,5
89,0
1,5
35 °C
before 1987
86,0
0,0
84,0
0,0
35 °C
1987 to 1992
88,0
0,0
84,0
0,0
35 °C
before 1987
84,0
1,5
82,0
1,5
35 °C
1987 to 1994
86,0
1,5
86,0
1,5
35 °C
after 1994
88,5
1,5
89,0
1,5
35 °C
before 1987
86,0
1,5
85,0
1,5
35 °C
1987 to 1994
86,0
1,5
86,0
1,5
35 °C
before 1987
89,0
1,0
95,0
1,0
20 °C
1987 to 1994
91,0
1,0
97,5
1,0
20 °C
after 1994
92,0
1,0
98,0
1,0
20 °C
from 1999
94,0
1,0
103
1,0
20 °C
Boiler type Change-fuel boilers
Solid fuel boilers (fossil fuel)
Standard boilers
Atmospheric gas boilers
after 1994 Burner replacement (only heating before 1978 boiler with forced draught burner) 1978 to 1994 Low temperature boilers Atmospheric gas boilers Circulation water heater (11 kW, 18 kW and 24 kW)
Heating boiler with forced draught burner
Burner replacement (only heating boiler with forced draught burner) Condensing boilers
Condensing boilers
Condensing boilers, improved
1)
1)
If standard values for "condensing boilers improved" are used for the calculation, the product value for the boiler installed must at least exhibit the above given efficiency.
NOTE
Test temperatures are given in Tables B.3 and B.4.
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B.3.2
Stand-by heat losses
Default value for the stand-by heat losses ĭgnr,ls.P0 depending on the generator power output is calculated by:
ĭgnr,ls,P0 = ĭPn ⋅
c5 § ĭPn · ¸ ⋅¨ 100 ¨© 1000 W ¸¹
c6 (B5)
where ɎPn
nominal power output,
c5, c6
parameters given in Table B.2. Table B.2 – Parameters for calculation of stand-by heat losses Boiler type Change-fuel boilers
Solid fuel boiler
Build year
c5 %
c6 -
Δθgnr,test,P0
until 1987
12,5
– 0,28
50
before 1978
12,5
– 0,28
50
1978 to 1994
10,5
– 0,28
50
after 1994
8,0
– 0,28
50
before 1978
8,0
– 0,27
50
1978 to 1994
7,0
– 0,3
50
after 1994
8,5
– 0,4
50
before 1978
9,0
– 0,28
50
1978 to 1994
7,5
– 0,31
50
after 1994
8,5
– 0,4
50
until 1994
7,5
– 0,30
50
after 1994
6,5
– 0,35
50
until 1994
3,0
0,0
50
after 1994
3,0
0,0
50
after 1994
2,4
0,0
50
until 1994
8,0
– 0,33
50
after 1994
5,0
– 0,35
50
until 1994
8,0
– 0,33
50
after 1994
4,8
– 0,35
50
after 1994
3,0
0,0
50
°C
Standard boilers
Atmospheric gas boilers
Heating boiler with forced draught burner (oil/gas)
Low temperature boilers Atmospheric gas boilers Circulation water heaters (combination boilers 11 kW, 18 kW and 24 kW) Combination boilers KSp Combination boilers DL
a)
b)
Heating boiler with forced draught burner (oil/gas) Condensing boilers Condensing boilers (oil/gas) Combination boilers KSp (11 a) kW, 18 kW and 24 kW)
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Boiler type
Build year
c5 %
c6 -
Δθgnr,test,P0
Combination boilers DL (11 b) kW, 18 kW and 24 kW)
after 1994
2,4
0,0
50
a)
KSp: Boiler with integrated domestic hot water heating working on the instantaneous principle with small storage tank (2 < V < 10 l).
b)
DL: Boiler with integrated domestic hot water heating working on the instantaneous principle with heat exchanger (V < 2 l).
°C
B.3.3
Correction factor taking into account variation of efficiency depending on generator average water temperature
B.3.3.1
Default values Table B.3 – Default values for full load correction factor fcorr,Pn Boiler average water temperature at boiler test conditions for full load șgnr,w,test,Pn
Correction factor fcorr,Pn
Standard boiler
70 °C
0,04 %/°C
Low temperature boiler
70 °C
0,04 %/°C
Gas condensing boiler
70 °C
0,20 %/°C
Oil Condensing boiler
70 °C
0,10 %/°C
Generator type
Table B.4 – Intermediate load correction factor fcorr,Pint Generator average water temperature at boiler test conditions for intermediate load șgnr,w,test, Pint
Correction factor fcorr,Pint
Standard boiler
50 °C
0,05 %/°C
Low temperature boiler
40 °C
0,05 %/°C
Gas condensing boiler
30 °C (*)
0,20 %/°C
Oil Condensing boiler
30 °C (*)
0,10 %/°C
Generator type
(*) Return temperature
For a condensing boiler, testing is not made with a defined generator average water temperature (average of the supply and return temperature), but with a return temperature of 30 °C. The efficiency corresponding to this return temperature can be applied for the generator average water temperature of 35 °C. B.3.3.2
Calculated values
Correction factor fcorr,Pn may be calculated using efficiency data from additional tests performed at a lower average water temperature, using the following equation:
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f corr, Pn =
ȘPn − ȘPn, add șgnr, w, test, Pn, add − șgnr, w, test, Pn
(B6)
where ȘPn
full load efficiency at standard test conditions with average water temperature șgnr,w,test,Pn;
ȘPn,add
full load efficiency with average water temperature șgnr,w,test,Pn,add.
Correction factor fcorr,Pint may be calculated using efficiency data from additional tests performed at a higher average water temperature, using the following equation:
f corr, Pint =
ȘPint − ȘPint, add șgnr, w, test, Pint, add − șgnr, w, test, Pint
(B7)
where ȘPint
intermediate load efficiency at standard test conditions with average water temperature șgnr,w,test,Pint;
ȘPint,add
intermediate load efficiency with average water temperature șgnr,w,test,Pint,add.
B.4
Auxiliary energy
Default value for the power consumption of auxiliary equipment is calculated by:
Paux,Px
§ ĭPn · ¸¸ = c7 + c8 ⋅ ¨¨ © 1000 W ¹
n
(B8)
where ɎPn
nominal power output;
c7, c8, n
parameters given in Table B.5.
Table B.5 – Parameters for calculation of power consumption of auxiliary equipment Boiler type
Change-fuel boilers
Automatically-fed pellet central 1) boiler
Automatically-fed wood chips 1) central boiler
c7
c8
W
W
Pn
0
45
0,48
Pint
0
15
0,48
P0
15
0
0
Pn
40
2
1
Pint
40
1,8
1
P0
15
0
0
Pn
60
2,6
1
Pint
70
2,2
1
P0
15
0
0
Load
n
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EN 15316-4-1:2008 (E)
Boiler type
c7
c8
W
W
Pn
40
0,148
1
Pint
40
0,148
1
P0
15
0
0
Pn
0
45
0,48
Pint
0
15
0,48
P0
15
0
0
Pn
40
0,148
1
Pint
40
0,148
1
P0
15
0
0
Pn
0
45
0,48
Pint
0
15
0,48
P0
15
0
0
Pn
0
45
0,48
Pint
0
15
0,48
P0
15
0
0
Pn
0
45
0,48
Pint
0
15
0,48
P0
15
0
0
Load
n
Standard boiler
Atmospheric gas boilers
Heating boiler with forced draught burner (oil/gas) Low temperature boilers
Atmospheric gas boilers
Circulation water heaters
Heating boiler with forced draught burner (oil/gas) Condensing boilers
Condensing boilers (oil/gas)
1)
B.5 B.5.1
With the use of fan-assisted firing, the values for Pn and Pint shall be increased by 40 %.
Recoverable generation thermal losses Auxiliary energy
Default value of the part of the auxiliary energy transmitted to the distribution sub-system frvd,aux is 0,75. The part of the auxiliary energy transmitted to the heated space frbl,aux is calculated by:
f rbl,aux = 1 − f rvd,aux B.5.2
(B9)
Generator envelope
The part of stand-by heat losses attributed to heat losses through the generator envelope is given by fgnr,env. Default values of fgnr,env are given in Table B.6.
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EN 15316-4-1:2008 (E)
Table B.6 – Part of stand-by heat losses attributed to losses through the generator envelope fgnr,env
Burner type
B.5.3
Atmospheric burner
0,50
Fan assisted burner
0,75
Default data according to boiler location Table B.7 – Temperature reduction factor and default installation room temperature Temperature reduction factor bbrm -
Installation room temperature θi,brm °C
1
θext
In the boiler room
0,3
13
Under roof
0,2
5
Inside heated space
0,0
20
Generator location Outdoors
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EN 15316-4-1:2008 (E)
Annex C (informative) Default values for parametering the boiler cycling method
C.1
Information on the method
C.1.1
Basic assumptions and intended use
This method is intended: ⎯
for use with existing boilers where data declared according to Council Directive 92/42/EEC [1] are not known;
⎯
to determine the effect of operating conditions on performances of condensing boilers.
This methodology is based on a physical analysis of losses (indirect method) and takes into account two operating conditions: ⎯
boiler with burner on;
⎯
boiler with burner off (stand-by).
Latent heat recovery is calculated separately from sensible heat losses. Data for heating system operating conditions, boiler and fuel are kept separate. This methodology is suitable for on-off, modulating, modular and condensing boilers, as well as for their combinations (like modulating, condensing boilers). All data given in this Annex are based on net calorific values Hi. If losses are to be calculated with respect to gross calorific value Hs, this is done with the procedure given in 4.7.
C.1.2
Known approximations
Additional losses during ignition cycles (ventilation before ignition) are not taken into account. Losses through the chimney with burner off are not easily measured. However, this loss factor has a reduced impact in modern boilers with air intake closure at stand-by.
C.2 C.2.1
Default specific losses Default data for calculation of thermal losses through the chimney with burner on Table C.1 – Default value of θgnr,w,m,test , Įch,on and fcorr,ch,on Description
Atmospheric boiler
θgnr,w,m,test
Įch,on
fcorr,ch,on
°C
%
%/°C
70
12
0,045
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EN 15316-4-1:2008 (E)
θgnr,w,m,test
Įch,on
fcorr,ch,on
°C
%
%/°C
Force draught gas boiler
70
10
0,045
Liquid fuel boiler
70
11
0,045
6
0,045
Description
Condensing boiler 1)
60
1)
Return temperature for condensing boilers.
Table C.2 – Default value of exponent nch,on Description
cmass,ch,on
nch,on
kg/kW
-
<1
0,05
1 to 2
0,1
>2
0,15
Wall mounted boiler Steel boiler Cast iron boiler NOTE
C.2.2
cmass,ch,on is the ratio between the mass of the heat exchange surface between flue gas and water and nominal combustion power in kg/kW.
Default values for calculation of thermal losses through the generator envelope
The default losses through the boiler envelope Įge are given by:
§ ĭcmb · ¸¸ © 1000 W ¹
α ge = c1 − c2 ⋅ log¨¨
(C1)
where c1, c2
parameters given in Table C.3;
Φcmb
boiler nominal combustion power. Table C.3 – Default value of parameters c1 and c2 c1
c2
%
%
Well insulated, high efficiency new boiler
1,72
0,44
Well insulated and maintained
3,45
0,88
Old boiler with average insulation
6,90
1,76
Old boiler, poor insulation
8,36
2,2
No insulation
10,35
2,64
Boiler insulation type
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EN 15316-4-1:2008 (E)
Table C.4 – Default value of factor kge,rvd and installation room temperature și,brm Boiler type and location
kge,rvd
θi,brm,test
θi,brm
-
°C
°C
Boiler installed within the heated space
0,1
20
Atmospheric boiler installed within the heated space
0,2
20
Boiler installed within a boiler room
0,7
Under roof
0,8
5
Boiler installed outdoors
1,0
External temperature
13
20
Default value for θgnr,w,m,test is 70 °C. Table C.5 – Default value of exponent nge Description
cge
nge
kg/kW
-
The primary pump is always running
0,0
The primary pump stops when the burner turns off and both are controlled by the room thermostat: ⎯
wall mounted boiler
⎯
steel boiler
⎯
cast iron boiler
NOTE
C.2.3
<1
0,15
1 to 3
0,10
>3
0,05
cge is the ratio between the total weight of the boiler (metal + refractory materials + insulating materials) and the nominal combustion power Φcmb of the boiler in kg/kW.
Default values for calculation of thermal losses through the chimney with the burner off Table C.6 – Default value of Įch,off Description
Įch,off %
Liquid fuel or gas fired boiler with the fan before the combustion chamber and automatic closure of air intake with burner off:
0,2
Premixed burners
0,2
Wall mounted, gas fired boiler with fan and wall flue gas exhaust
0,4
Liquid fuel or gas fired boiler with the fan before the combustion chamber and no closure of air intake with burner off: Chimney height 10 m
1,0
Chimney height > 10 m
1,2
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EN 15316-4-1:2008 (E)
Įch,off
Description
%
Atmospheric gas fired boiler: Chimney height 10 m
1,2
Chimney height > 10 m
1,6
Table C.7 – Default value of exponent nch,off Description
cch,off
nch,off
kg/kW
-
The primary pump is always running
0,0
The primary pump stops when the burner turns off and both are controlled by the room thermostat ⎯
wall mounted boiler
⎯
steel boiler
⎯
cast iron boiler
NOTE
<1
0,15
1 to 3
0,10
>3
0,05
cch,off is the ratio between the total weight of the boiler (metal + refractory materials + insulating materials) and the nominal combustion power Φcmb of the boiler in kg/kW.
Default value for θi,brm,test is 20 °C. Default value for θgnr,w,m,test is 70 °C.
C.3
Default values for calculation of auxiliary energy
The default auxiliary power Pbr and Ppmp are given by
§ ĭ · Px = c3 + c4 ⋅ ¨¨ cmb ¸¸ © 1000 W ¹
n
(C2)
where Φcmb is the boiler nominal combustion power.
Table C.8 – Default value of c3 and c4 for the calculation of electrical power consumption of auxiliary devices Description Pbr, atmospheric gas boilers Pbr, forced draught burners Pbr, automatically-fed pellet central boiler
1)
Pbr, automatically-fed wood chips central boiler
1)
c3
c4
n
W
W
-
40
0,148
1
0
45
0,48
40
2
1
60
2,6
1
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EN 15316-4-1:2008 (E)
Description Ppmp, primary pump (all boilers)
c3
c4
n
W
W
-
100
2
1
1)
With the use of fan-assisted firing, the values for Pn and Pint shall be increased by 40 %.
NOTE
If there is no primary pump or if it is taken into account in the distribution part (see Figures 3 and 4) then Ppmp = 0
Table C.9 – Default value of auxiliary energy recovery factors Value
Description
C.4
-
kbr
0,8
kpmp
0,8
Additional default data for multistage and modulating burners
The default minimum combustion power of the boiler is given by:
Φcmb,min = Φcmb · fmin
(C3)
where fmin
parameter given in Table C.10;
Φcmb
boiler nominal (maximum) combustion power. Table C.10 – Parameter fmin for multistage and modulating burners fmin
Description
-
Gas boiler
0,3
Liquid fuel boiler
0,5
Table C.11 – Default value of θgnr,w,m,test,min and Įch,on,min
θgnr,w,m,test,min
Įch,on,min
°C
%
Atmospheric boiler
70
11
Force draught gas boiler
70
9
Oil boiler
70
10
Description
Condensing boiler 1)
50
1)
5
Return temperature for condensing boilers.
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EN 15316-4-1:2008 (E)
The default auxiliary power Pbr,min is calculated with equation (C2) using c3, c4 and n given in Table C.12. Table C.12 – Default value of c3, c4 and n for the calculation of electrical power consumption of auxiliary devices at minimum combustion power Description Pbr, atmospheric gas boilers Pbr, forced draught burners Pbr, automatically-fed pellet central boiler
1)
Pbr, automatically-fed wood chips central boiler 1)
C.5
1)
c3
c4
n
W
W
-
20
0,148
1
0
15
0,48
60
1,8
1
70
2,2
1
With the use of fan-assisted firing, the values for Pn and Pint shall be increased by 40 %.
Additional default data for condensing boilers
Table C.13 – Default fuel data for condensation heat recovery calculation Fuel Property
Symbol
Unit
Natural gas
Propane
Butane
Light oil EL
1 Nm³
1 Nm³
1 Nm³
1 kg
(Groningen)
Unit mass of fuel Gross calorific value
Hs
kJ/kg or kJ/Nm³
35 169 kJ/Nm³
101 804 kJ/Nm³
131 985 kJ/Nm³
45 336 kJ/kg
Net calorific value
Hi
kJ/kg or kJ/Nm³
31 652 kJ/Nm³
93 557 kJ/Nm³
121 603 kJ/Nm³
42 770 kJ/kg
Stoichiometric dry air
Vair,st,dry
Nm³/kg or Nm³/Nm
8,4 Nm³/Nm³
23,8 Nm³/Nm³
30,94 Nm³/Nm³
11,23 Nm³/kg
Stoichiometric dry flue gas
Vfg,st,dry
Nm³/kg or Nm³/Nm
7,7 Nm³/Nm³
21,8 Nm³/Nm³
28,44 Nm³/Nm³
10,49 Nm³/kg
Stoichiometric water production
mH2O,st
kg/kg or kg/Nm³
1,405 kg/Nm³
3,3 kg/Nm³
4,03 kg/Nm³
1,18 kg/kg
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EN 15316-4-1:2008 (E)
Table C.14 – Default values for the calculation of Įcond Description
Symbol
Unit
Case
Value
Combustion air relative humidity
xair
%
All cases
50
Flue gas relative humidity
xfg
%
All cases
100
Temperature difference between boiler return water temperature and flue gas temperature
ǻșwfg
°C
Șgnr,Pn 102
20
Șgnr,Pn < 102
60
Temperature difference between boiler return water temperature and flue gas temperature at minimum power
Șgnr,Pmin 106
5
ǻșwfg,min
°C
Șgnr,Pn < 106
20
Flue gas oxygen combustion power
contents
at
maximum
XO2,fg,dry
-
All cases
6
Flue gas oxygen combustion power
contents
at
minimum
XO2,fg,dry,min
-
Modulation of both air and gas
6
Only gas modulation
15
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EN 15316-4-1:2008 (E)
Annex D (informative) General part default values and information
D.1
Control factor Table D.1 – Default values for control factor fctrl in equation (2) fctrl
Description All control types
1,0
Other values may be specified in a national annex, provided that emission control losses have not been taken into account in the emission part (EN 15316-2-1). NOTE In the EN 15316-X-X series of standards, the effect of heat emission control is taken into account in the emission and control part (EN 15316-2-1). The effect of the control of generation is taken into account through losses and efficiency corrections according to the operating temperature of the generator.
Table D.2 is an example of such table to be given in a national annex. Table D.2 – Sample default national table for control factor in equation (2) Boiler type Floor standing boiler Wall hanged boiler
D.2
Control type
fctrl
Outdoor temperature controlled
1,00
Outdoor temperature controlled
1,03
Room temperature controlled
1,06
Intermediate load
Intermediate load ĭint is given by:
Φint = ΦPn · ȕint
(D1)
For gas and oil fuelled generators, the default value of ȕint is 0,3.
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EN 15316-4-1:2008 (E)
Annex E (informative) Calculation example for seasonal boiler performance method based on system typology
E.1
Introduction
This example is based on the method described in Annex A.
E.2
Input data Table E.1 – Boiler data Description
Symbol
Boiler type
Value Condensing boiler
ĭPn
Nominal power
70 kW
Efficiency test results produced in accordance with standard tests as required for the Council Directive 92/42/EEC about Boiler Efficiency [1]
Șgnr,Pn
96 % (full-load net efficiency)
Șgnr,Pint
106 % (30 % part-load net efficiency)
Auxiliary electric power at full load
Paux,Pn
210 W
Auxiliary electric power at intermediate load
Paux,Pint
60 W
Auxiliary electric power at zero load
Paux,P0
10 W
Fuel used
Natural gas
Ignition method
No permanent pilot flame
Burner type
Modulating, fan assisted
Table E.2 – Data according to other parts of this standard Description Heat output NOTE
Symbol QH,gen,out
Value 465,7 GJ = 129,36 MWh
Example estimated as 220 days x 86 400 s/day x 70 000 W x 0,35 = 465,7 GJ.
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EN 15316-4-1:2008 (E)
E.3
Calculation procedure Table E.3 – Calculation procedure Procedure step
References
Calculation details and results
1 Determine fuel for boiler type
Natural gas
2 Obtain test data
Șgnr,Pn = 96 %; Șgnr,Pint = 106 % ȘPn,net,max = 101 % hence Șgnr,Pn,net = 96 %
3 Reduce to maximum net efficiency values (Table A.1)
Table A.1
4 Convert the efficiencies from net to gross values
Table A.2
Net-to-gross conversion factor: fntg = 0,901
Eq. (A1)
Șgnr,Pn,gross = 96 % x 0,901 = 86,5 %
ȘPint,net,max = 107 % hence Șgnr,Pint,net = 106 %
Șgnr,Pint,gross = 106 % x 0,901 = 95,5 % 5 Categorise the boiler (i) Select the boiler category
condensing, natural gas fuelled, modulating, regular boiler
(ii) If a gas or LPG boiler, permanent pilot light
fplt = 0 (no permanent pilot light)
(iii) For a storage combination boiler
Not a storage combination boiler
(iv) For a condensing combined primary storage unit
Not a CPSU
(v) For a storage combination boiler or a CPSU
Not a storage combination boiler or a CPSU
6 Calculate seasonal efficiency (i) Choose appropriate SEDB_UK Table A.3 equation Table A.4 Table A.5
Equation n° 102 selected
§ ȘPn,gross + ȘPint,gross 2 ©
η gen,gross = ¨¨
· ¸¸ − 2,0 − 4 ⋅ f plt ¹
§ 86,5 % + 95,5 % · ¸ − 2,0 − 4 × 0 = 89,0 % 2 © ¹
(ii) Substitute values
η gen, gross = ¨
(iii) Convert back to net seasonal efficiency
Eq. (A2)
η gen,net =
7 Calculate total generation thermal loss
Eq. (A3)
QH,gen,ls = 465,7 GJ ⋅
8 Calculate fuel heat requirement Eq. (A4)
1 ⋅ 89 % = 98,8 % 0,901 100 − 98,8% = 5,75 GJ = 1,6 MWh 98,8%
E H,gen,in =
465,7 GJ × 100 = 471,4 GJ = 130,96 MWh 98,8 %
ĭ H,gen, out =
465,7 GJ = 24,5 kW 19 008 000 s
9 Calculate auxiliary energy Calculate generation average power
5.3.3.1
Calculate load factor
5.3.3.2
Eq. (8)
Eq. (9) Select equation
5.3.6
β gnr =
24,5 kW = 0,35 70 kW
ȕgnr > ȕint then use equation (26)
73 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
Procedure step Calculate actual auxiliary power
References 5.3.6 Eq. (26)
Calculate total auxiliary energy
5.3.6
Calculation details and results
Paux,Px = 60 W +
0,35 − 0,3 × (210 W − 60 W ) = 70,7 W 1 − 0,3
Wgnr,aux = 70,7 W × 19 008 000 s + 0 W × 0 s = 1,034 GJ = 373 kWh
Eq. (24) 10 Calculate total recoverable thermal loss
E.4
QH,gen,ls,rbl = 0 No recoverable generation thermal loss is taken into account
Output data (connection to other parts of EN 15316) Table E.4 – Output data Description
Symbol
Value
Fuel heat requirement
EH,gen,in
471,4 GJ = 130 960 kWh
Total generation thermal loss
QH,gen,ls
5,75 GJ = 1 600 kWh
Auxiliary energy
WH,gen,aux
1,034 GJ = 373 kWh
Recoverable thermal loss
QH,gen,ls,rbl
0 J = 0 kWh
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EN 15316-4-1:2008 (E)
Annex F (informative) Calculation examples for case specific boiler efficiency method
F.1
Condensing boiler example, data declared by the manufacturer
F.1.1
Input data Table F.1 – Boiler data Description
Symbol
Boiler type
Value Condensing boiler
Nominal power (heat output) Efficiency test results produced in accordance with standard tests as required for the Council Directive 92/42/EEC about Boiler Efficiency [1]
ĭPn Șgnr,Pn
70 kW 96 % (full-load net efficiency) șgnr,w,test,Pn = 70 °C
Șgnr,Pint
106 % (30 % part-load net efficiency) șgnr,w,test,Pint = 30 °C (return temperature)
Auxiliary electric power at full load
Paux,Pn
210 W
Auxiliary electric power at intermediate load
Paux,Pint
60 W
Auxiliary electric power at zero load
Paux,P0
10 W
Fuel used
Natural gas
Burner type
Modulating, fan assisted
Boiler location
Boiler room
Type of control
Depending on outside temperature
Generation circuit typology
Direct connection of boiler
Table F.2 – Data according to design or to other parts of this standard Description Operation time of the generator Generator heat output
Symbol
Value
tgen
2 592 000 s = 720 h (*)
QH,gen,out
80,9 GJ = 22 472 kWh
Generation average temperature (**)
θgen,f
48,9 °C
Generation return temperature (**)
θgen,r
37,7 °C
Distribution flow rate
V'dis
1 207 l/h
(*)
Example estimated as 30 days, continuous operation
(**)
Generation temperatures are equal to distribution temperatures. See calculation example in H.6.
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EN 15316-4-1:2008 (E)
F.1.2
Calculation procedure Table F.3 – Calculation procedure Procedure step
References
Calculation details and results Direct connection of the generator
Calculation of boiler average and H.2 return temperature
θgnr,w,m = θgen,m = 48,9 °C θgnr,w,r = θgen,r = 37,7 °C
Calculation of generation average power Calculation of load factor
Calculation of corrected boiler efficiency at full load
Calculation of corrected thermal losses at full load
Calculation of corrected boiler efficiency at intermediate load
Calculation of corrected thermal losses at intermediate load
5.3.3.1 Eq. (8) 5.3.3.2 Eq. (9)
ĭ H, gen, out =
β gnr =
80,9 GJ = 31,2 kW 2 592 000 s
31,2 kW = 0,446 (single boiler, only heating load) 70 kW
5.3.5.1
fcorr,Pn = 0,20 %/°C (Table B.3, gas condensing boiler)
Table B.3
șgnr,w,test,Pn = 70 °C (Table B.3, gas condensing boiler)
Eq. (14)
η gnr, Pn,corr = 96 % + 0,20 %/ °C × (70 °C − 48,9 °C) = 102,4 %
5.3.5.1 Eq. (15)
ĭgnr,ls,Pn,corr =
(100% − 102,4%) × 70 kW = - 1 674 W 102,4%
5.3.5.2
fcorr,Pint = 0,20 %/°C (Table B.4, gas condensing boiler)
Table B.4
șgnr,test,Pint = 30 °C (Table B.4, gas condensing boiler)
Eq. (16)
η gnr, Pint, corr = 106% + 0,20 %/ °C × (30°C − 37,7 °C) = 104,45 %
5.3.5.2 Eq. (17)
ĭgnr,ls,Pint, corr =
(100% − 104,45%) × 21kW = - 895 W 104,45%
c5 = 4,8 % (Table B.2, gas condensing boiler, after 1994)
Calculation of boiler stand-by heat loss at 0 % load
B.3.2
c6 = - 0,35 (Table B.2, gas condensing boiler, after 1994)
Table B.2
Δθgnr,test,P0 = 50 °C (Table B.2, gas condensing boiler, after 1994)
Eq. (B5)
5.3.5.3 Calculation of corrected thermal losses at 0 % load
Table B.7 Eq. (18)
Calculation of corrected thermal losses at actual load
5.3.5.4
Calculation of total generator thermal loss
5.3.5.4
Calculation of total generation thermal loss
5.3.5.5
Calculation of auxiliary power at actual load
5.3.6
Eq. (21)
Eq. (22)
Eq. (23)
Eq. (26)
ĭgnr,ls,P0 = 70 000 W ×
4,8 § 70 000 W · ¸ ר 100 ¨© 1 000 W ¸¹
− 0,35
= 760 W
θi,brm = 13 °C (Table B.7, in the boiler room) 1,25
§ 48,9 °C − 13 °C · ¸¸ ĭgnr,ls,P0,corr = 760 W × ¨¨ 50 °C © ¹
= 502 W
Equation (21) because ĭPx = ĭH,gen,out > ĭPint
ĭgnr,ls,Px =
31,2 kW − 21 kW × (−1674 W + 895 W) − 895 W = - 1 057 W 70 kW − 21 kW
Qgnr,ls = - 1,026 kW x 720 h = - 761 kWh = - 2 740 MJ
QH,gen,ls = ¦ Qgnr,ls = - 761 kWh = - 2 740 MJ Equation (26) because ȕgnr > ȕint
Paux,Px = 60 W +
0,446 − 0,30 × (210 W − 60 W ) = 91,3 W 1 − 0,30
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EN 15316-4-1:2008 (E)
Procedure step
References
Calculation of generator total auxiliary energy
5.3.6
Calculation of generation total auxiliary energy
5.3.6
Calculation of generator recovered auxiliary energy
Eq. (24)
WH,gen,aux = ¦ Wgnr,aux
5.3.7.1
No recovered auxiliary energy is explicitly taken into account because it is already included in test data
Eq. (B9) Table B.7 5.3.7.1
5.3.7.2 Table B.6 Eq. (30) Calculation of total generation recovered auxiliary energy
5.3.7.3
Calculation of total generation recoverable thermal losses
5.3.7.3
Calculation of total generation heat input
5.3.8
F.1.3
= 65,7 kWh = 236,5 MJ
Qgnr,aux,rvd = 0
Eq. (29) Calculation of generator thermal losses (generator envelope)
Wgnr,aux = 91,3 W x 720 h + 0 W x (720 h – 720 h) = 65,7 kWh
Eq. (27)
B.5.1 Calculation of generator recoverable auxiliary energy (to the heated space)
Calculation details and results
Eq. (31)
Eq. (32)
Eq. (1)
frvd,aux = 0,75 frbl,aux = 1 – 0,75 = 0,25 bbrm = 0,3 (Table B.7, in the boiler room) Qgnr,aux,rbl = 65,7 kWh x (1 – 0,3) x 0,25 = 11,5 kWh = 41,4 MJ
fgnr,env = 0,75 (Table B.6, fan assisted burner) Qgnr,ls,env,rbl = 502 W x (1 – 0,3) x 0,75 x 720 h = 73,1 kWh = 263,3 MJ No recovered auxiliary energy is explicitly taken into account because it is already included in test data, hence QH,gen,aux,rvd = 0 QH,gen,ls,rbl = 73,1 kWh + 11,5 kWh = 84,6 kWh = 304,7 MJ
EH,gen,in = 22 472 kWh – 0 kWh – 761 kWh = 21 711 kWh = 78 160 MJ
Output data (connection to other parts of EN 15316) Table F.4 – Output data Description
Symbol
Value
Fuel heat requirement
EH,gen,in
21 711 kWh = 78 160 MJ
Total generation thermal loss
QH,gen,ls
- 761 kWh = - 2 740 MJ
Auxiliary energy
WH,gen,aux
65,7 kWh = 236,5 MJ
Recoverable thermal loss
QH,gen,ls,rbl
84,6 kWh = 304,7 MJ
F.1.4
Conversion of net values to gross values
If losses are to be calculated according to gross calorific value, then the following procedure applies.
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EN 15316-4-1:2008 (E)
Table F.5 – Net to gross conversion procedure Procedure step
References
Calculation details and results Default values from Table C.13 for natural gas:
4.7 Calculation of the latent heat of Eq. (4) condensation Table C.13
Correction of fuel input
4.7 Eq. (5)
Correction of total losses
4.7 Eq. (6)
F.2
Hs = 35,17 MJ/Nm³ Hi = 31,65 MJ/Nm³ Q lat = 78 160 MJ ×
35,17 MJ/Nm 3 − 31,65MJ/Nm 3 = 8 693 MJ = 2 415 kWh 31,65MJ/Nm 3
EH,gen,in,grs = 78 160 MJ + 8 693 MJ = 86 852 MJ = 24 126 kWh
QH,gen,ls,grs = - 2 740 MJ + 8 693 MJ = 5 952 MJ = 1 653 kWh
Standard boiler example, default data
F.2.1
Input data Table F.6 – Boiler data Description
Symbol
Boiler type
Value Standard, atmospheric boiler
Nominal power (heat output)
ĭPn
70 kW
Build year
1988
Fuel used
Natural gas
Burner type
Single stage, on-off
Burner location
Boiler room
Type of control
Constant temperature = 70 °C
Generation circuit typology
Independent flow rate
Table F.7 – Data according to design or to other parts of this standard Description Operation time of the generator Generator heat output
Symbol
Value
tgen
2 592 000 s = 720 h (*)
QH,gen,out
80,9 GJ = 22 472 kWh
Generation flow temperature
θgen,f
70 °C
Generation return temperature (**)
θgen,r
37,7 °C
Distribution flow rate
V'dis
1 207 l/h
Generation flow rate
V'gen
6 000 l/h
(*)
Example estimated as 30 days, continuous operation.
(**)
Generation return temperature is equal to return distribution. See calculation example in H.6.
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EN 15316-4-1:2008 (E)
F.2.2
Calculation procedure Table F.8 – Calculation procedure Procedure step
Calculation of generation average power
Calculation of boiler flow, return and average temperature
References 5.3.3.1 Eq. (8)
Calculation details and results
ĭ H,gen, out =
80,9 GJ = 31,2 kW 2 592 000 s
H.3
Independent flow rate. Generation flow rate is higher than distribution flow rate
Eq. (H4)
θgnr,w,f = 70 °C (design and set value)
Eq. (H5)
θgnr,w,r = 70 °C −
H.5
Calculation of load factor
31 200 W = 65,5 °C 1000 kg/m³ × 4 186 J/kg ⋅ °C × 1,67 × 10 − 3 m³/s
Eq. (H11)
θgnr,w,m = 70 °C + 65,5 °C = 67,8 °C 2
5.3.3.2
β gnr =
Eq. (9)
31,2 kW = 0,446 (single boiler, only heating load) 70 kW
c1 = 82,5 % (Table B.1, atmospheric gas boiler, 1978 to 1994) B.3.1 Calculation of full load efficiency
Calculation of corrected boiler efficiency at full load
Calculation of corrected boiler thermal losses at full load
Eq. (B2)
§ 70 000 W · ¸¸ = 86,2 % Șgnr,Pn = 82,5% + 2,0% × log¨¨ © 1 000 W ¹
5.3.5.1
fcorr,Pn = 0,04 %/°C (Table B.3, standard boiler)
Table B.3
șgnr,w,test,Pn = 70 °C (Table B.3, standard boiler)
Eq. (14)
Șgnr,Pn,corr = 86,2 % + 0,04 %/°C x (70 °C - 67,8 °C) = 86,3 %
5.3.5.1
ĭgnr,ls,Pn,corr =
Eq. (15) B.3.1
Calculation of intermediate load efficiency
Calculation of corrected boiler efficiency at intermediate load
Calculation of corrected boiler thermal losses at intermediate load
c2 = 2,0 % (Table B.1, atmospheric gas boiler, 1978 to 1994)
Table B.1
Table B.1
(100% − 86,3 %) × 70 kW = 11 132 W 86,3 %
c3 = 78,0 % (Table B.1, atmospheric gas boiler, 1978 to 1994) c4 = 3,0 % (Table B.1, atmospheric gas boiler, 1978 to 1994)
Eq. (B3)
§ 70 000 W · ¸¸ = 83,5 % Șgnr,Pint = 78% + 3,0% × log¨¨ © 1 000 W ¹
5.3.5.2
fcorr,Pint = 0,05 %/°C (Table B.4, standard boiler)
Table B.4
șgnr,w,test,Pint = 50 °C (Table B.4, standard boiler)
Eq. (16)
Șgnr,Pint,corr = 83,5 % + 0,05 %/°C x (50 °C - 67,8 °C) = 82,6 %
5.3.5.2 Eq. (17)
ĭPint = 30 % x ĭPn = 21 kW ĭgnr, ls, Pint, corr =
(100 % − 82,6 %) × 21 kW = 4 409 W 82,6 %
c5 = 7,0 % (Table B.2, atmospheric gas boiler, 1978 to 1994)
Calculation of boiler stand-by heat loss at 0 % load
B.3.2
c6 = - 0,30 (Table B.2, atmospheric gas boiler, 1978 to 1994)
Table B.2
Δθgnr,test,P0 = 50 °C (Table B.2, atmospheric gas boiler, 1978 to 1994)
Eq. (B5)
ĭgnr,ls,P0 = 70 000 W ×
7,0 § 70 000 W · ¸ ר 100 ¨© 1 000 W ¸¹
− 0,30 = 1 370 W
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EN 15316-4-1:2008 (E)
Procedure step
References 5.3.5.3
Calculation of corrected thermal losses at 0 % load
Table B.7 Eq. (18)
Calculation of corrected thermal losses at actual load
5.3.5.4
Calculation of total generator thermal loss
5.3.5.4
Calculation of total generation thermal loss
5.3.5.5
Eq. (21)
Eq. (22)
Eq. (23)
Calculation details and results
θi,brm = 13 °C (Table B.7, in the boiler room)
§ 67,8 °C − 13 °C · ¸¸ ĭgnr,ls,P0,corr = 1370 W × ¨¨ 50 °C © ¹
1,25
= 1 535 W
Equation (21) because ĭPx = ĭH,gen,out > ĭPint ĭ gnr,ls,Px =
31,2 kW − 21 kW × (11132 W − 4 409 W) + 4 409 W = 5 810 W 70 kW − 21 kW
Qgnr,ls = 5,81 kW x 720 h = 4 183 kWh = 15 060 MJ
QH,gen,ls = ¦ Qgnr,ls = 4 183 kWh = 15 060 MJ c7 = 40 W (Table B.5, boiler with atmospheric burner up to 250 kW)
Calculation of auxiliary power at full load
B.4
c8 = 0,148 W (Table B.5, boiler with atmospheric burner up to 250 kW)
Table B.5
n = 1 (Table B.5, boiler with atmospheric burner up to 250 kW)
Eq. (B8)
§ 70 000 W · ¸¸ = 50 W Paux , Pn = 40W + 0,148W × ¨¨ © 1000 W ¹
1
c7 = 40 W (Table B.5, boiler with atmospheric burner up to 250 kW) Calculation of auxiliary power at intermediate load
B.4
c8 = 0,148 W (Table B.5, boiler with atmospheric burner up to 250 kW)
Table B.5
n = 1 (Table B.5, boiler with atmospheric burner up to 250 kW)
Eq. (B8)
§ 21000W Paux , P int = 40W + 0,148W × ¨¨ © 1000W
1
· ¸¸ = 43 W ¹
c7 = 15 W (Table B.5, boiler with atmospheric burner up to 250 kW) Calculation of auxiliary power at zero load
B.4
c8 = 0 W (Table B.5, boiler with atmospheric burner up to 250 kW)
Table B.5
n = 0 (Table B.5, boiler with atmospheric burner up to 250 kW)
Eq. (B8)
§ 21000W · Paux , P 0 = 15W + 0 × ¨¨ ¸¸ = 15 W © 1000W ¹
Calculation of auxiliary power at actual load
5.3.6
Calculation of generator total auxiliary energy
5.3.6
Calculation of generation total auxiliary energy
5.3.6
Calculation of generator recovered auxiliary energy
Eq. (26)
Eq. (24)
0
Equation (26) because ȕgnr > ȕint
Paux , Px = 43W +
0,446 − 0,30 × (50 W − 43W ) = 44,6 W 1 − 0,30
Wgnr,aux = 44,6 W x 720 h + 0 W x (720 h – 720 h) = 32,1 kWh
Eq. (27)
WH , gen,aux = ¦Wgnr ,aux
5.3.7.1
No recovered auxiliary energy is explicitly taken into account because it is already included in default data
= 32,1 kWh = 115,7 MJ
Qgnr,aux,rvd = 0
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EN 15316-4-1:2008 (E)
Procedure step
References B.5.1
Calculation of generator recoverable auxiliary energy (to the heated space)
Eq. (B9) Table B.7 5.3.7.1 Eq. (29) 5.3.7.2
Calculation of generator thermal losses (generator envelope)
Table B.6 Eq. (30)
Calculation of total generation recovered auxiliary energy
5.3.7.3
Calculation of total generation recoverable thermal losses
5.3.7.3
Calculation of total generation heat input
5.3.8
F.2.3
Eq. (31)
Eq. (32)
Eq. (1)
Calculation details and results frvd,aux = 0,75 frbl,aux = 1 – 0,75 = 0,25 bbrm = 0,3 (Table B.7, in the boiler room) Qgnr,aux,rbl = 32,1 kWh x (1 – 0,3) x 0,25 = 5,6 kWh = 20,2 MJ
fgnr,env = 0,50 (Table B.6, atmospheric burner) Qgnr,ls,env,rbl = 1 535 W x (1 – 0,3) x 0,50 x 720 h = 149,2 kWh = 537,2 MJ No recovered auxiliary energy is explicitly taken into account because it is already included in default data, hence QH,gen,aux,rvd = 0 QH,gen,ls,rbl = 149,2 kWh + 5,6 kWh = 154,8 kWh = 557,4 MJ
EH,gen,in = 22 472 kWh – 0 kWh + 4 183 kWh = 26 656 kWh = 95 960 MJ
Output data (connection to other parts of EN 15316) Table F.9 – Output data Description
Symbol
Value
Fuel heat requirement
EH,gen,in
26 656 kWh = 95 960 MJ
Total generation thermal loss
QH,gen,ls
4 183 kWh = 15 060 MJ
Auxiliary energy
WH,gen,aux
32,1 kWh = 115,7 MJ
Recoverable thermal loss
QH,gen,ls,rbl
154,8 kWh = 557,4 MJ
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EN 15316-4-1:2008 (E)
Annex G (informative) Calculation examples for boiler cycling method
G.1
Modulating condensing boiler
G.1.1
Input data Table G.1 – Boiler data Description
Symbol
Value
References Boiler type
Modulating condensing boiler
Nominal power (heat input)
ĭcmb
74 kW
Heat losses through the chimney with burner on (full load)
Įch,on
4%
Boiler return water temperature at test conditions for Įch,on Electrical power consumption of boiler auxiliaries at full load (before the burner) Electrical power consumption of boiler auxiliaries (after the burner)
θgnr,w,r,test
60 °C
Pbr
210 W
Ppmp
0 W (direct connection to distribution sub-system, no primary pump)
ĭref
74 kW
Data from default tables Reference power
If not specified, it is assumed equal to ĭcmb Correction factor for calculation of Įch,on,corr
fcorr,ch,on Table C.1
Exponent for the load factor for calculation of Įch,on,corr Heat losses through the boiler envelope
nch,on Table C.2 Įge Table C.3 Eq. (C1)
Reduction factor of boiler envelope thermal losses Exponent for the load factor for calculation of Įge,corr Heat losses through the chimney with the burner off Exponent for the load factor for calculation of Įch,off,corr
kge,rvd Table C.4 nge Table C.5 Įch,off Table C.6 nch,off Table C.7
0,045 %/°C Condensing boiler 0,1 Steel boiler High efficiency well insulated boiler
§ 74 000 W · = 0,90 % ¸¸ Įge = 1,72 % − 0,44 % × log¨¨ © 1 000 W ¹ 0,7 Boiler located inside boiler room 0 Continuous circulation of water 0,2 % Boiler with automatic closure of air intake at burner off 0 Continuous circulation of water
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EN 15316-4-1:2008 (E)
Description
Symbol
Value
References Temperature of test room for Įge and Įch,off
θi,brm,test
20 °C
C.2.2 C.2.3 Boiler average water temperature at test conditions for Įge and Įch,off
θgnr,w,m,test
70 °C
C.2.2 C.2.3
Recovery factor of Pbr
kbr Table C.9
Recovery factor of Ppmp
kpmp
0,8 Default 0,8
Table C.9
Default
Minimum combustion power of the boiler
ĭcmb,min
18 kW
Heat losses through the chimney with burner on (minimum load)
Įch,on,min
3%
Pbr,min
60 W
ǻșwfg
25 °C
Additional data for modulating burner
Electrical power consumption of boiler auxiliaries at minimum combustion power Additional data for condensing boiler Temperature difference between boiler return water temperature and flue gas temperature (full load) Dry flue gas oxygen contents (full load)
XO2 fg,dry
3%
Additional data from default tables for condensing boiler Combustion air relative humidity
xair
50 %
Table C.14 Flue gas relative humidity
xfg
100 %
Table C.14 Additional data for condensing multistage or modulating boiler Temperature difference between boiler return water temperature and flue gas temperature at minimum combustion power Flue gas oxygen contents at minimum combustion power
ǻșwfg,min
6 °C
XO2,fg,dry,min
4%
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EN 15316-4-1:2008 (E)
Table G.2 – Data according to design or to other parts of this standard Description
Symbol
Operation time of the generator Generator heat output
Value
tgen
2 592 000 s = 720 h (*)
QH,gen,out
80,9 GJ = 22 472 kWh
Generation average temperature (**)
θgen,f
48,9 °C
Generation return temperature (**)
θgen,r
37,7 °C
Distribution flow rate
V'dis
1 207 l/h
Installation room temperature
θi,brm
13 °C (default value for boiler room, Table C.4)
θair
Combustion air temperature
8 °C (monthly external average temperature)
(*)
Example estimated as 30 days, continuous operation.
(**)
Generation temperature is equal to average distribution. See calculation example in H.6.
Table G.3 – Data according to fuel Description
Symbol
Fuel
Value Natural gas (Groningen)
Gross calorific value
Hs
35 169 kJ/Nm³
Net calorific value
Hi
31 652 kJ/Nm³
Stoichiometric dry air
Vair,st,dry
8,4 Nm³/Nm³
Stoichiometric dry flue gas
Vfg,st,dry
7,7 Nm³/Nm³
Stoichiometric water production
mH2O,st
1,405 kg/Nm³
NOTE
G.1.2
Data from Table C.13
Calculation procedure Table G.4 – Calculation procedure
Procedure step Calculation of boiler average and return temperature
References
Calculation details and results Direct connection of the generator
H.2
θgnr,w,m = θgen,m = 48,9 °C θgnr,w,r = θgen,r = 37,7 °C
Selection of calculation procedure
The boiler is modulating and is equipped with a condensing boiler, therefore the calculation procedure of 5.4.7 applies with extensions specified in 5.4.8.
Calculation of Įcond,min (*) Calculate flue gas temperature Calculate actual flue gas volume
5.4.8.7 Eq. (74) 5.4.8.7 Eq. (75)
θfg = 37,7 °C + 6 °C = 43,7 °C
Vfg,dry = 7,7 Nm 3 ⋅
(ǻșwfg,min applied in eq. (74))
20,94% = 9,52 Nm³ (X O2,fg,dry,min applied in eq. (75)) 20,94% − 4%
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EN 15316-4-1:2008 (E)
Procedure step Calculate actual combustion air Calculate air and flue gas saturation humidity Calculate combustion air absolute humidity Calculate flue gas absolute humidity Condensate balance
References 5.4.8.7 Eq. (76)
Calculate actual latent heat of condensation Calculate the condensation recovery factor
Vair,dry = 8,4 m³ + 9,52 m³ – 7,7 m³ = 10,22 m³
5.4.8.7
mH2O,air,sat = 9,45 g/m³ with θair = 8 °C
Table 3
mH2O,fg,sat = 77,84 g/m³ with θfg = 43,7 °C
5.4.8.7 Eq. (77) 5.4.8.7 Eq. (78) 5.4.8.7 Eq. (79)
Calculate specific latent heat of condensation
Calculation details and results
5.4.8.7 Eq. (80) 5.4.8.7 Eq. (81) 5.4.8.7 Eq. (83)
mH2O,air = 9,45g/m 3 × 10,2m 3 ×
50% = 48 g 100%
mH2O,fg = 77,84g/m3 × 9,52m 3 ×
100% = 741 g 100%
mH2O,cond,min = 1 405 g + 48 g – 741 g = 712 g
hcond,fg,min = 2 500 600 J/kg – 43,7 °C x 2 435 J/kg·°C = 2,394 kJ/g
Qcond,min = 712 g x 2,394 kJ/g = 1,71 MJ
Į cond, min = 100 ×
1,71 MJ = 5,39 % 31,6 MJ
Try single stage procedure using minimum power output data Step 1
5.4.6
Single generator: QH,gen,out = 80,9 GJ
Step 2
5.4.6
Operation time: tgen = 720 h
Step 3
5.4.6
Set ȕcmb = 1
5.4.3 Step 4
Eq. (40)
5.4.5 Eq. (50) Eq. (52) Eq. (53)
Step 6
5.4.6 Eq. (54)
Step 7
Į ge, corr = 0,9 % × 0,7 ×
Eq. (41) Eq. (44)
Step 5
Į ch,on,min,cond = [3% + (37,7°C − 60 °C) × 0,045 %/°C] × 10,1 − 5,39% = - 3,39
5.4.6
α ch, off, corr = 0,2 % ×
48,9 °C − 13 °C 0 = 0,45 % ×1 70 °C − 20 °C
48,9 °C − 13 °C 0 = 0,14 % ×1 70 °C − 20 °C
Qbr = 60 W x 0,80 x 720 h = 34,6 kWh Qpmp = 0 W x 0,80 x 720 h = 0 kWh WH,gen,aux = 34,6 kWh / 0,80 = 43,2 kWh 22 472 kWh − 0 kWh + 0,14 % + 0,45 % 720 h × 74 kW = = 1,687 18 kW + 0,8× 0,06 kW 18 kW 100 % × − × (− 3,39 %) + 0,14 % 74 kW 74 kW 100 % ×
β cmb
After each iteration, the results are: ȕcmb = 1,685 … 1,685 … 1,685
Since the final value is greater than 1, the burner is modulating between minimum and maximum power and ĭcmb,avg has to be calculated according to the procedure in 5.4.7.3. Step 1 Step 2
5.4.7.3 5.4.3 Eq. (41)
Single generator: QH,gen,out = 80,9 GJ
α ge,corr = 0,9% × 0,7 ×
(48,9°C − 13°C) × 10 (50°C)
= 0,45
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EN 15316-4-1:2008 (E)
Procedure step
References 5.4.3
Step 3
Eq. (40) 5.4.5
Step 4 Step 5 Step 6a
α ch,on,max,corr = [4% + (37,7°C − 60 °C) × 0,045%/°C] × 10,1 = 3 % Qbr = 210 W x 0,80 x 720 h = 121 kWh Qbr,min = 60 W x 0,80 x 720 h = 34,6 kWh
5.4.7.3
ĭcmb,avg = 74 kW
5.4.7.3
α ch,on,avg,corr = 2 % + (3 % − 2 %) ×
5.4.8.6 Eq. (72) 5.4.8.6
Step 6c
α ch,on,min,corr = [3 % + (37,7°C − 60 °C) × 0,045%/°C] × 10,1 = 2 %
Eq. (50)
Eq. (58) Step 6b
Calculation details and results
Eq. (73)
Δθ wfg,avg = 6 °C + (25 °C − 6 °C)×
74 kW − 18 kW = 3 % 74 kW − 18 kW
74 kW − 18 kW = 25 °C 74 kW − 18 kW
X O2,fg,dry,avg = 4 % + (3 % − 4 %) ×
74 kW − 18 kW =3% 74 kW − 18 kW
Calculation of Įcond using șfg = 37,7 °C + 25 °C = 62,7 °C and XO2,fg,dry = 3 % yields: Vfg,dry = 8,99 m³ Vair,dry = 9,69 m³ mH2O,air,sat = 9,45 g/m³ with θair = 8 °C Step 6d
5.4.8.7
mH2O,fg,sat = 226,11 g/m³ with θfg = 62,7 °C mH2O,air = 46 g mH2O,fg = 2 032 g mH2O,cond = - 581 g Įcond,avg = 0 % because mH2O,cond < 0.
5.4.8.6
Step 6e
Eq.(71) 5.4.7.3
Step 7
Eq. (59) 5.4.7.3
Step 8
Eq. (60)
Step 9 Step 6a (2
nd
iteration)
nd
iteration)
nd
iteration)
ĭcmb,avg
74 kW − 18 kW = 121 kWh 74 kW − 18 kW
22 472 kWh − 0 kWh − 121kWh 0,45 + × 74 kW 720 h 100 = 32,347 kW = 3% 1− 100
Iterate againg from step 6 with ĭcmb,avg = 32,347 kW
5.4.7.3
α ch,on,avg,corr = 2 % + (3 % − 2 %) ×
5.4.8.6 Eq. (72)
Step 6c (2
Qbr,avg = 34,6 kWh + (121 kWh − 34,6 kWh )×
5.4.7.3
Eq. (58) Step 6b (2
Įch,on,avg,cond = 3 % - 0 % = 3 %
5.4.8.6 Eq. (73)
32,35kW − 18 kW = 2,26 % 74 kW − 18 kW
Δθ wfg, avg = 6 °C + (25 °C − 6 °C) ×
32,35 kW − 18 kW = 10,9 °C 74 kW − 18 kW
X O2,fg,dry,avg = 4 % + (3 % − 4 %)×
32,35 kW − 18 kW = 3,74 % 74 kW − 18 kW
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EN 15316-4-1:2008 (E)
Procedure step
References
Calculation details and results Calculation of Įcond using șfg = 37,7 °C + 10,9 °C = 48,6 °C and XO2,fg,dry = 3,74 % yields Vfg,dry = 9,38 m³ Vair,dry = 10,08 m³ mH2O,air,sat = 9,45 g/m³ with θair = 8 °C
Step 6d (2
nd
iteration)
5.4.8.7
mH2O,fg,sat = 103,98 g/m³ with θfg = 48,6 °C mH2O,air = 48 g mH2O,fg = 975 g mH2O,cond = 478 g hcond,fg = 2,382 kJ/g Įcond,avg = 3,59 %
Step 6e (2
nd
iteration)
5.4.8.6 Eq. (71)
Step 7 (2
nd
iteration)
5.4.7.3 Eq. (59)
Step 8 (2
nd
iteration)
Step 9 (further iterations)
5.4.7.3 Eq. (60)
5.4.7.3 5.4.7.3
Step 10
Eq. (61) 5.4.7.3
Step 11
Eq. (62) 5.4.7.3
Step 12
Eq. (63) 5.4.7.3
Step 13
Eq. (64) 5.4.7.3
Step 14
Eq. (65)
Įch,on,avg,cond = 2,26 % - 3,59 % = - 1,34 % Qbr,avg = 34,6 kWh + (121 kWh − 34,6 kWh ) ×
ĭcmb,avg
32,35 kW − 18 kW = 56,74 kWh 74 kW − 18 kW
22 472 kWh − 0 kWh − 56,7 kWh 0,45 + × 74 kW 720 h 100 = 31,05 kW = − 1,34 % 1− 100
Iterations starting again from step 6 yield the following values for ĭcmb,avg: 30,991 kW … 30,988 kW and converges to 30,988 kW EH,gen,in = 30,988 kW x 720 h = 22 311 kWh = 80 321 MJ ĭ br,avg = 60 W + (210 W − 60 W ) ×
30,988 kW − 18 kW = 94,8 W 74 kW − 18 kW
WH,gen,aux = 720 h x (94,8 W + 0 W) = 68,2 kWh
WH,gen,aux,rvd = 720 h x (94,8 W x 0,8 + 0 W x 0,8) = 54,6 kWh = 197 MJ
QH,gen,ls = 22 311 kWh – 22 472 kWh + 55 kWh = - 106 kWh = - 382 MJ
(*)
Calculation referred to the unit mass of fuel (Nm³ in this example).
NOTE
All iterations shown converge in 2 or 3 runs.
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EN 15316-4-1:2008 (E)
G.1.3
Output data (connection to other parts of EN 15316) Table G.5 – Output data Description
Symbol
Value
Fuel heat requirement
EH,gen,in
22 311 kWh = 80 321 MJ
Total generation thermal loss
QH,gen,ls
- 106 kWh = - 382 MJ
Auxiliary energy
WH,gen,aux
68,2 kWh
Recoverable thermal loss
QH,gen,ls,rbl
0 kWh = 0 MJ
G.2
Standard, on-off atmospheric boiler
G.2.1
Input data Table G.6 – Boiler data Description
Symbol
Value
References Boiler type Nominal power (heat input) Boiler average water temperature at test conditions for Įch,on
Single stage atmospheric boiler ĭcmb
74 kW
θgnr,w,m,test
70 °C
ĭref
74 kW
Data from default tables Reference power
Heat losses through the chimney with burner on (full load) Correction factor for calculation of Įch,on,corr
5.4.2
If not specified, it is assumed equal to ĭcmb
Įch,on
12 %
Table C.1 fcorr,ch,on Table C.1
Exponent for the load factor for calculation of Įch,on,corr Heat losses through the boiler envelope
nch,on Table C.2 Įge Table C.3 Eq. (C1)
Reduction factor of boiler envelope thermal losses Exponent for the load factor for calculation of Įge,corr Heat losses through the chimney with the burner off
kge,rvd Table C.4 nge Table C.5 Įch,off Table C.6
Atmospheric boiler 0,045 %/°C Atmospheric boiler 0,15 Cast iron boiler Old boiler with average insulation
§ 74 000 W · = 3,61 % ¸¸ © 1 000 W ¹
α ge = 6,79 % − 1,76 % × log¨¨ 0,7
Boiler located inside boiler room 0 Continuous circulation of water 1,6 % Atmospheric gas fired boiler, chimney height > 10 m
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EN 15316-4-1:2008 (E)
Description
Symbol
Value
References Exponent for the load factor for calculation of Įch,off,corr Temperature of test room for Įge and Įch,off
nch,off Table C.7
θi,brm,test
0 Continuous circulation of water 20 °C
C.2.2 C.2.3 Boiler average water temperature at test conditions for Įge and Įch,off
θgnr,w,m,test
70 °C
C.2.2 C.2.3 c3 = 40 W (atmospheric burner) Pbr
Auxiliary power before the combustion chamber
C.3
c3 = 100 W (all boilers)
C.3
c4 = 2 W (all boilers)
Eq. (C2)
kbr Table C.9
Recovery factor of Ppmp
1
§ 74 000 W · ¸¸ = 51 W Pbr = 40 W + 0,148 W × ¨¨ © 1 000 W ¹
Ppmp
Table C.8
Recovery factor of Pbr
n = 1 (atmospheric burner)
Table C.8 Eq. (C2)
Auxiliary power after the combustion chamber
c4 = 0,148 W (atmospheric burner)
kpmp Table C.9
n = 1 (all boilers) 1
§ 74 000 W · ¸¸ = 248 W Ppmp = 100 W + 2 W × ¨¨ © 1 000 W ¹ 0,8 Default 0,8 Default
Table G.7 – Data according to design or to other parts of this standard Description Operation time of the generator Generator heat output
Symbol
Value
tgen
2 592 000 s = 720 h (*)
QH,gen,out
80,9 GJ = 22 472 kWh
Generation average temperature (**)
θgen,f
48,9 °C
Generation return temperature (**)
θgen,r
37,7 °C
Distribution flow rate
V'dis
1 207 l/h
Installation room temperature
θi,brm
13 °C (default value for boiler room, Table C.4)
(*)
Example estimated as 30 days, continuous operation.
(**)
Generation temperature is equal to average distribution. See calculation example in H.6.
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EN 15316-4-1:2008 (E)
G.2.2
Calculation procedure Table G.8 – Calculation procedure
Procedure step
References
Calculation of generation average power
Calculation of boiler flow, return and average temperature
Calculation details and results
ĭ H,gen, out =
80,9 GJ = 31,2 kW 2 592 000 s
H.3
Independent flow rate. Generation flow rate is higher than distribution flow rate
Eq. (H4)
θgnr,w,f = 70 °C (design and set value)
Eq. (H5)
θgnr,w,r = 70 °C −
H.5 Eq. (H11)
31 200 W = 65,5 °C 1000 kg/m³ × 4186 J/kg ⋅ °C × 1,67 × 10 −3 m³/s
θgnr,w,m = 70 °C + 65,5 °C = 67,8 °C 2
Single stage procedure according to 5.4.6 Step 1
5.4.6
Single generator: QH,gen,out = 80,9 GJ
Step 2
5.4.6
Operation time: tgen = 720 h
Step 3
5.4.6
Set ȕcmb = 1
5.4.3 Eq. (40)
Step 4
α ch,on,corr = [12% + (70°C − 67,8°C) × 0,045%/°C] × 10,15 = 11,9 % α ge,corr = 3,61 % × 0,7 ×
Eq. (41) Eq. (44) 5.4.5 Eq. (50)
Step 5
Eq. (52) Eq. (53)
α ch.off, corr = 1,6 % ×
Eq. (54)
Step 7
5.4.6 5.4.3
Step 4 (2
nd
iteration)
Eq. (40)
Qpmp = 248 W x 0,80 x 720 h = 142,8 kWh WH,gen,aux = 29,4 kWh / 0,8 + 142,8 kWh / 0,8 = 215 kWh
5.4.5 Step 5 (2
iteration)
22 472 kWh − 142,8kWh + 1,75 % + 2,77 % = 0,516 720 h × 74 kW = 74 kW + 0,8× 0,051kW 74 kW 100 % × − ×11,9 % + 1,75% 74 kW 74 kW 100 % ×
β cmb
Iterate again from step 4 with ȕcmb = 0,516
α ch,on,corr = [12% + (70°C − 67,8°C) × 0,045%/°C] × 0,5160,15 = 10,8 %
α ge, corr = 3,61 % × 0,7 ×
Eq. (41) Eq. (44)
nd
67,8 °C − 13 °C 0 = 1,75 % ×1 70 °C − 20 °C
Qbr = 51 W x 0,80 x 720 h x 1 = 29,4 kWh
5.4.6 Step 6
Eq. (50) Eq. (52) Eq. (53)
67,8 °C − 13 °C 0 = 2,77 % ×1 70 °C − 20 °C
α ch, off,corr = 1,6 % ×
67,8 °C − 13 °C × 0,516 0 = 2,77 % 70 °C − 20 °C
67,8 °C − 13 °C × 0,516 0 = 1,75 % 70 °C − 20 °C
Qbr = 51 W x 0,80 x 720 h x 0,516 = 15,2 kWh Qpmp = 248 W x 0,80 x 720 h = 142,8 kWh WH,gen,aux = 15,2 kWh / 0,8 + 142,8 kWh / 0,8 = 197,5 kWh
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EN 15316-4-1:2008 (E)
Procedure step
References
Calculation details and results
5.4.6 Step 6 (2
nd
iteration)
Eq. (54)
22 472 kWh − 142,8kWh + 1,75% + 2,77 % = 0,510 720 h × 74 kW = 74 kW + 0,8× 0,051kW 74 kW 100 % × − ×10,8 % + 1,75% 74 kW 74 kW 100 % ×
β cmb
After each iteration, further results are: Step 7 (further iterations)
5.4.6
ȕcmb = 0,510 … 0,510 … 0,510 and ȕcmb converges to 0,510 (WH,gen,aux converges to197,3 kWh)
5.4.6
Step 8
Eq. (55) 5.4.6
Step 9 NOTE
G.2.3
Eq. (56)
EH,gen,in = 74 kW x 720 h x 0,51 = 27 169 kWh = 97 808 MJ QH,gen,ls = 27 169 kWh – 22 472 kWh + 15 kWh + 143 kWh = 4 855 kWh = 17 478 MJ
All iterations shown converge in 2 or 3 runs.
Output data (connection to other parts of EN 15316) Table G.9 – Output data Description
Symbol
Value
Fuel heat requirement
EH,gen,in
27 169 kWh = 97 808 MJ
Total generation thermal loss
QH,gen,ls
4 855 kWh = 17 478 MJ
Auxiliary energy
WH,gen,aux
197,3 kWh
Recoverable thermal loss
QH,gen,ls,rbl
0 kWh = 0 MJ
91 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
Annex H (informative) Boiler water temperature calculation
H.1
Boiler flow temperature and return temperature
The following data:
⎯
θgnr,w,m average water temperature in the boiler;
⎯
θgnr,w,r average return water temperature to the boiler;
are required to correct heat loss coefficients and calculate condensate production according to actual operation conditions. Calculation of flow rates is not fully detailed in this standard. Any design flow rate value shall be calculated separately with appropriate methods. Calculation is performed starting with the emission sub-system and taking into account the hydraulic design or the actual hydraulic layout as well as the operation of the heating system. Subsequently, the effect of the type of generation circuit is taken into account. A generation circuit may include mixing, recirculation or buffer connections. Therefore, generation circuit flow rate and temperatures may differ from boiler flow rate and temperatures. In this annex, the following indices are applied:
⎯
gnr for boiler values (generator);
⎯
gen for generation circuit values.
An example of a generation circuit is shown in Figure H1.
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EN 15316-4-1:2008 (E)
Figure H1 - Sample generation circuit Key GNR PMP
generator (boiler) primary pump
BV
balancing valve
θgen,f θgen,r
generation circuit flow temperature, which is also the distribution flow temperature θdis,f generation circuit return temperature, which is also the distribution return temperature θdis,r generation circuit flow rate, which is also the distribution flow rate V'dis
V'gen
ΦH,gen,out V'gnr
θgnr,w,f θgnr,w,r θgnr,w,m
H.2
heat power output of the generation circuit boiler flow rate boiler flow temperature boiler return temperature boiler average water temperature
Boiler flow rate is the same as the distribution flow rate (no by-pass)
If the boiler flow rate V'gnr is the same as the generation circuit flow rate V'gen, then
θ gnr,w,f = șgen,f
(H1)
θ gnr,w,r = șgen,r
(H2)
V 'gnr = V 'gen
(H3)
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EN 15316-4-1:2008 (E)
Examples of such circuits are given in Figure H2. NOTE
Flow in the buffer is controlled and not allowed to cool or heat completely.
Key GNR
generator (boiler)
PMP BV
primary pump balancing valve
BUF
buffer
Figure H2 - Boiler flow rate is the same as generation circuit flow rate
H.3
Boiler flow rate is not the same as the distribution flow rate (by-pass connection or recirculation pump)
If the boiler flow rate V'gnr is greater than the generation circuit flow rate V'gnr (V'gnr > V'gen), then:
θ gnr,w,f = θ gen,f
θ gnr,w,r = șgen,w,f −
ĭgnr,out ȡw ⋅ cw ⋅ V 'gnr
(H4)
(H5)
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EN 15316-4-1:2008 (E)
where
NOTE
ȡw
density of water;
cw
specific heat of water;
ĭgnr,out
boiler heat output.
θgnr,w,r is higher than θgen,w,r.
If the boiler flow rate V'gen is less than the generation circuit flow rate V'gen (V'gnr < V'gen), then:
θ gnr,w,r = θ gen,r θ gnr,w,f = șgen,w,r + NOTE
(H6)
ĭgnr,out ȡw ⋅ cw ⋅ V 'gnr
(H7)
θgnr,f is higher than θgen,f.
θgnr,w,r and θgnr,w,f are in any case given by:
ª
θ gnr,w,r = max «șgen,r ; șgen,w,f − «¬
ª
θ gnr,w,f = max «șgen,f ; șgen,w,r + «¬
º » ȡw ⋅ cw ⋅ V' gnr »¼
(H8)
º » ȡw ⋅ cw ⋅ V 'gnr »¼
(H9)
ĭgnr,out
ĭgnr,out
which combine equations (H4) to (H7). Examples of such circuits are given in Figure H3.
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EN 15316-4-1:2008 (E)
Key GNR PMP
generator (boiler) primary pump
BV BUF
balancing valve buffer
Figure H3 – Boiler flow rate is not the same as generation circuit flow rate NOTE 1 The flow rate V’gnr through the boiler is the average flow rate. Using a buffer allows low flow rate operation of the generation circuit through intermittent operation of the boiler pump. NOTE 2 Some old systems incorporate a condensate prevention pump. Its flow rate adds to the generation circuit flow rate to give the boiler flow rate.
H.4
Parallel connection of boilers
If more boilers are connected in parallel, the common return temperature θgnr,r and the resulting flow temperature θgnr,f are calculated according to H.3 using the total flow rate and the total heat output. The average heat power output Φgnr,out,i and flow rate V'gnr,i of each boiler have to be determined.
96 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
Then the flow temperature θgnr,w,f,i of each boiler i is calculated with:
θ gnr,w,f,i = șgnr,w,r +
ĭgnr,out,i ȡw ⋅ cw ⋅ V 'gnr,i
(H10)
An example of a parallel connection is given in Figure H4.
Key GNR1, GNR2 PMP1, PMP2
generators (boilers) primary pumps
BV
balancing valve
Figure H4 - Parallel connection of boilers
H.5
Boiler average water temperature
The boiler average water temperature θgnr,w,m is given by:
θ gnr,w,m =
șgnr,w,f + șgnr,w,r
2
(H11)
97 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
H.6
Example of water temperature calculation Table H.1 – Input data Symbol
Description
Value
References QH,dis,out
Distribution sub-system output
75 125 MJ = 20 868 kWh
EN15316-2-3 QH,dis,in
Distribution sub-system input
80 900 MJ = 22 472 kWh
EN15316-2-3 Type of heat emitters
radiators
Nominal power of installed heat emitters
ĭemr,n
Design temperature difference between emitters and room temperature
ǻșem,des nemr
Exponent of the emitters
70 000 W 50 °C 1,3
Internal temperature of heated space
și
20 °C
Calculation period
tci
720 h
Operation time of distribution
tdis
720 h (continuous operation)
Type of heat emitter control
Thermostatic valves șemr,f
Set emitters flow temperature Type of distribution circuit
53 °C Mixing valve
șdis,f
Set distribution flow temperature
60 °C
Table H.2 – Calculation procedure Procedure step
References
Calculation details and results
Emitters temperature calculation according to EN 15316-2-3:2007, Clauses 7 and 8.1. Emitters load
EN 15316-2-3 Eq. (38)
Calculation of the emitters average temperature
EN 15316-2-3
Calculation of the emitters return temperature
EN 15316-2-3
Eq. (43)
Eq. (45)
β dis =
22 472 kWh = 0,414 70 kW × 720 h 1/1,3
șemr,m = 20 °C + 50 °C x 0,414
= 45,4 °C
șemr,r = max (2 x 45,4 °C – 53 °C; 2 °C) = 37,7 °C
Distribution circuit temperature calculation according to EN 15316-2-3:2007, Clause 8.3. șdis,f = 60 °C (set value)
Distribution circuit flow temperature Distribution circuit return temperature
EN 15316-2-3 Eq. (49)
ĭdis,in = 22 472 kWh/720 h = 31,21 kW
Distribution input power Distribution circuit flow rate
șdis,r = 37,7 °C (the same as emitters flow temperature)
EN 15316-2-3 Eq. (50)
.
Vdis =
31 211 W = 0,33 kg/s = 1 207 kg/h 1000 kg/m³ × 4186 J/kg ⋅ °C × (60 °C − 37,7 °C )
98 UNI EN 15316-4-1:2008
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EN 15316-4-1:2008 (E)
Bibliography [1] Council Directive 92/42/EEC of 21 May 1992 about the efficiency requirements of the new gas or oil boilers [2] EN 15316-1, Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies – Part 1: General [3] EN 15316-3-3, Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies – Part 3.3: Domestic hot water systems, generation [4] EN ISO 9488, Solar energy – Vocabulary (ISO 9488:1999) [5] ISO 13602-2, Technical energy systems – Methods for analysis – Part 2: Weighting and aggregation of energywares
99 UNI EN 15316-4-1:2008
Licenza d'uso concessa a UNIVERSITA' CENTRO ATENEO DOC.POLO MONTE DAGO per l'abbonamento anno 2008. Licenza d'uso interno su postazione singola. Riproduzione vietata. E' proibito qualsiasi utilizzo in rete (LAN, internet, etc...)
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Riproduzione vietata - Legge 22 aprile 1941 Nº 633 e successivi aggiornamenti.