ISHRAE INSTITUTE OF
HEAT HEA T LOAD LOAD ESTIMATIONS
EXCELLENCE
ISHRAE INDIAN SOCIETY SOCI ETY OF HEATING HEATING REFRIGERATING REFRIGERA TING AND AIRCONDITIONING ENGINEERS ISHRAE INSTITUTE OF EXCELLENCE # 76, I FLOOR, KASTURI COMPLEX, MISSION ROAD, BANGALORE – 560 027, PHONE: 080-22245523, 41495045 WEB SITE: www.iiebangalore.org
MESSAGE FROM THE CHAIRMAN
ISHRAE INSTITUTE OF EXCELLENCE (IIE) was conceived after an intense deliberation and pondering over the pros and cons of different seminars and workshops conducted by ISHRAE and ASHRAE for the HVAC&R and allied subjects in order to provide a beneficial learning Institute of Excellence. The aspirants are those who are eager to enhance their professional competency in pace with & up to date with worldwide technological advancement. The HVAC & R industry is facing acute shortage of Skilled Manpower at all levels, Further there has been no adequate technical Training and Refresher courses for such Team of Engineers. Keeping this in mind, IIE, Bangalore has been instrumental in organising Refresher Courses for the Working Engineers. The course has been designed in such a way that the programs are conducted in the evenings and during week ends. IIE Bangalore could refresh more than 500 Engineers so far. It is the wish of IIE Bangalore that such dissemination of Knowledge should not stop at Bangalore and should spread to all places. As such IIE has consolidated the lecture notes and ha s prepared a Power point presentation of such lectures so that all IIE Centers in the country can take the benefit. The notes and the power point presentation will come in handy for the IIE Centres and the Faculties so that the courses can be conducted with ease. The Refresher course notes by and large are compiled from the Seminars and Workshops conducted by ISHRAE Bangalore Chapter over the years. Further IIE Bangalore has taken a positive step to work with the Industry and Institutions. IIE in association with ISHRAE Bangalore Chapter and ASHRAE South India Chapter is planning to facilitate the industry to draw Manpower from Engineering Colleges, Polytechnics, ITIs and Cream of Science Graduate and train them in such a way that they can be used directly by the industry. This is at a time when the industry is facing shortage of manpower as well as shortage of time in training such manpower. I take this opportunity to thank the Trustees of ISHRAE Foundation Trust, Core Management Committee members, Faculties and the ISHRAE Head Quarters for their support in the great work of Dissemination of Knowledge. As Knowledge is Power, please make use of these Refresher course Notes and reap the best of the benefits. Wish you all the Best! D. NIRMAL RAM. CHAIRMAN, IIE, IFT Bangalore
ACKNOWLEDGEMENT
IIE acknowledges with thanks the following eminent personalities whose lectures are used to compile this refresher course materials. D. NIRMAL RAM, G.V. RAO, LESLIE D’SOUZA, MAHESH U. V. ACHAR, K. V. PRADEEP, RAKESH SAHAY AND MANY OTHERS
Bibilography : ISHRAE Hand Book ASHRAE Hand Books Carrier System Design Manual
KUMAR,
Ishrae Institute of Excellence, Chennai
Heat Load Estimations
HEAT LOAD ES TIMATION LOAD COMPONENTS:
U ndoubtedly one of the primary reasons for failuresin air-conditioning plants is due to improper estimation
1.
of the heat load and failure to take into account various factors which affect it. T he load estimation i s based on the actual instantaneous peak load. It is not possible to
SO LA R G A IN a. T hrough Wall b. T hrough Roof
measure this actual instantaneous peak load but only can be esti mated. B efore esti mati ng thi s load a complete survey of the buildi ng, if the building exists, or the plans, incase of a new building, has to be done. A n accurate survey of the various param eters will result
c. T hrough G lass
2.
in a realistic load estimation.
T R A N SM ISSIO N G A IN a. T hrough Wall
T he followi ng data need to be collected: b. T hrough C eiling 1.
O rientation of the building and latitude.
2.
A p plication.
3.
D imensions of the building.
4.
H eight up to ceiling.
5.
H eight up to false ceiling
6.
Is the roof exposed?
7.
D epth of the beam and projections of the column
c. Equipment
8.
Size and number of windows.
e. System gain
9.
Whether windows are shaded?
c. T hrough Floor d. T hrough G lass 3.
a. P eople b. Lighting
d. Infiltration
f. M iscellaneous Sources
10. M aterial of construction of walls, ceiling/ roof.
4.
11. O utside dry and wet bulb temperatures (all seasons) 12.
R O O M IN T ER N A L L O A D
O UT D O O R LO AD a. Fresh A ir System G ain
Inside design dry bulb temperature and relative
HEAT LOAD CONCEPTS
humidity. A good designer has to calculate the cooli ng load at
13. N o. of persons.
optimum design conditions. T he load so calculated
14. A re they smoki ng? T ype of activity
should not be too high or too less. T he space heat gain
15. L ighting load and type of lights.
is a resultant effect of sensible and latent heat. T he sensible heat is the phenomenon of temperature,
16. M achinery loadswith diversity
whereas the latent heat is the stored heat in the form
17. O ther additional loads.
of moisture or metabolism rate.
18. D uration of operation
T he other heat load components can be classified into:-
19. Space to locate various equipments
a)
L oads originated from heat sources outside or external to the conditioned space.
20. Ventilation required 21. D etails of exhaust, if any.
b)
L oadswithin the conditioned space.
22.
c)
L oad occurring from heat gains or losses with
L evel of cleanliness to be maintained
moving cool fluids to and from the conditioned
23. A vailability of soft water and electricity
space. 24. O ther relevant information
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Ishrae Institute of Excellence, Chennai
Heat Load Estimations
NOTE:
people and equipm ent load. T he size of the diversity factor has to be based on the accurate judgment of
A ir-conditi oning load estimations are based on quantity of ai r required to produce the design conditi ons. A s such in high altitudes where air conditioning is required,
the user or his engineer. H eat may be stratifi ed in room s with hi gh ceiling and where the air is exhausted through the ceiling or the return air is taken above the false ceiling.
when the density decreases, more quantity of ai r i s required to satisfy the given sensible load. T he weight of the air to meet the latent load decreases owing to the higher wet bulb temperature and relative humidity,
OUTDOOR DESIGN CONDITIONS
the wet bulb temperature decreases as the altitude increases corresponding to the sea level.
While calculating the heat load the outside conditions play a vital role in estimating the heat load.
L oad estimations are based on either normal design
In A merica A SH R A E data are regarded as the industry standard. In I ndia ISH R A E has started working on the project on establishing and compiling authentic weather data for various places in India.
conditions or maximum design conditions. In normal design condi tions, the outdoor design condi tions are the simultaneously occurring dry bulb and wet bulb temperature and humidity which are permitted to exceed a few times a year for shorter periods. T his is generally recom mended for comfo rt and normal industrial applications and it is occasionally permissible to exceed the inside design conditions.
T he ambient air properties and solar intensitieschanges with different elevation, latitude and longitude. While selecting the refrigeration capacity of the plant for year round air conditioning the cooling load for summer and monsoon weather whichever is higher is selected.
In cases where inside temperature swings on the higher side is not tolerable then the design should be based on the maximum outside design conditions.
In general for Indian climatic conditions 4P M is the average time for solar heat gain and average daily range of temperature (M aximum D B – M inimum D B
T he maxim um design dry and wet bulb temperatures are simultaneous peaks and not individual peaks that are considered for the load estimation. A constant temperature is required for m any industrial applications instead of a temperature level.
in a day) vary from 15 to 20 degree F (L ocal conditions are to be referred).
INSIDE DESIGN CONDITIONS:
T he actual cooli ng load will generally be below the
T he human body considers itself comfortable when it can maintain an average body temperature between 97 degree F and 100 degree F. It becomes the task of
peak total i nstantaneous heat gain, thus requiri ng a smaller equipment to perform a specific job. If the equipment is allowed to run at a few degrees higher than design requirement during peak periods, a smaller capacity plant will meet the requirement. A smaller system running for longer duration at full load will result
air-conditioning to maintain the environment around the body within this comfort zone of conditions. In general 75 degree F D B and 50% R H is considered the design conditi ons for human comfort. H owever, these conditions may vary depending upon the environm ental requirement and applications.
in saving in power and is more efficient than a bigger system running at part load conditions for a shorter duration. R easons for the difference in the actual heat gain and the total instantaneous peak heat gain is due to storage effect, diversity and stratifi cation. If the cooling capacity
S OLAR HEAT GAIN T he primary weather related variable influencing the sensible cooling load for a building is solar radiation.
supplied to the space matches with the cooling load, the temperature in the space remai ns constant. O n the contrary, i f the cooli ng capacity suppli ed to the space is more than the cooling load then lower
T he effect of solar radiati on i s more pronounced on exposed surfaces. R oom sensible heat i s calculated as under.
temperatures are mai ntained. P recooli ng a space below the design conditions increases the storage of
T he heat transfer rate q is given by equation. q= U A (T 1-T 2)
heat at the time of peak load. P recooling is useful in reducing the cooling load in applications such as
Where q= H eat transfer rate in B tu per hour.
churches, theaters and auditoriums.
U = C oefficient of overall heat transfer between the adjacent and the conditioned space in B tu/ h sqft-
D iversity of cooli ng load results from the probable non occurrence of part of the cooling load such as lighting,
deg.F.
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Ishrae Institute of Excellence, Chennai
Heat Load Estimations
A = A rea of the separating section in sqft.
M ore heat i s reflected and less heat is transmi tted inside the conditioned area if the angle of incidence is more.
T 1= A verage air temperature in adjacent space deg. F
T he total solar heat gain in the conditi oned area is the heat transmi tted together with around 40% of the heat absorbed by the glass windows.
T 2= A ir temperature in conditi oned space deg. F U = 1/ R where R = A ddition of thermal resistance of all the surfaces coming in between the conditioned space and adjacent space. (R efer tables for T hermal
D epending on the latitudes, for each month i n a year and for different exposures and on different timings
R esi stance R of various building and in sulatin g materials).
there are tablesfor the solar heat gain. T his solar heat gain in B tu / hr/ sqft. area is multiplied with the area of the glass and the factor dependi ng on the shade. For
SOLAR HEAT GAIN THROUGH GLASS
ordi nary glass the factor i s 1. 0 whereas for inside Venetian blinds of light color the factor is 0.56.
T he heat from the sun is partly scattered, partly reflected and partly absorbed by the atmosphere. T he scattered radia ti on i s called as di ffused radiati on. T he solar heat which directly comes through the atmosphere is termed as direct radiation. It enters the air-conditioned space through glass windows and is absorbed by the objects and air in the conditioned area. O rdinary glass absorbs a smaller percentage of the solar heat say round 6% and reflects or transmits the remai ning. T he amount of reflection is dependent on the angle of incidence which is the angle between the perpendicular to the glass surface and the sun rays.
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Ishrae Institute of Excellence, Chennai
Heat Load Estimations
the film coefficient, when worki ng out the transmi ssion
S OLAR AND TRANSMIS S ION HEAT GAIN THROUGH EXPOSED WALLS:
co-efficient. It is the resistance offered by the film of air which clings to the surface of the wall. T he
H eat flows from higher level to the lower whenever
resistance is more when the air is still and is less when
there exi sts a temperature difference. T he rate at
there is wind velocity.
which the heat flows inside varies with the resistance im posed by that material. T he solar heat gain on
Whenever a false ceiling is provided in a room having
the exposed wall does not become an instantaneous
an exposed roof, the space enclosed between the
room load. T he heat is absorbed by the external
false ceiling and the roof is called as attic space. If
wall and is conducted slowly into the inner layers
this attic space is not properly ventilated the space
of the wall and only the convected and radiated
temperature may exceed the outside temperature.
heat from the inner surface of the wall is the room
T he space temp erature can be work ed out
load. D ue to this unsteady state of heat flow i t is a
considering that the rate of heat flow from outside
general practice to consider an equivalent
into the attic space is equal to the rate of flow of
temp erature
heat from the attic space into the room.
dif ference.
T he
equivalent
temperature difference is the temperature
TRANSMISSION GAIN GLASS & PARTITIONS
difference that results in total heat flow through the structure as caused by the variable solar radiation and outdoor temperature.
THROUGH
T here will be heat transmission through the glass apart
T he reciprocal of the total resistance offered by the
from the solar gain due to the difference in
wall is called the transmi ssio n coefficient U . It is
temperature between the conditioned and non-
the rate at which the heat is transferred through
conditioned space. Si mi larly partitions/ ceiling/ floor
the wall and is expressed in B T U / hr/ Sq. ft/ deg.F
will also have heat transmi ssion. T hey are work ed
temp. diff. T he equivalent temp erature difference
out by considering the area, temperature difference
for different thickness of walls with different
and the factor.
exposures and timings are available in the tables
INTERNAL LOADS
enclosed. T hese equivalent temperature differences are worked out with an outside temperature of 95
PEOPLE
deg. F and an inside temperature of 80 deg.F. A s such corrections to equivalent temperatures are to
H eat is generated withi n a human body by
be made for different conditi ons. U nlik e the heat
metabolism. T he metabolic rate depends on the
gain tables for glass which constitutes only the solar
nature of activity. T he enclosed table will give the
gain and not the transmi ssion gain, this equivalent
sensible and latent load due to personnel depending
temperature considers the solar heat as well as the
on the type of activity and the inside temperature.
transmission heat gain due to the difference in
B efore the heat load estim ation, the exact number
temperature between outside and inside conditions.
of persons inside the conditioned area has to be
In addition to the resistance offered by the various
ascertained properly for an accurate estimation.
components in the wall, we have to tak e into account
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Ishrae Institute of Excellence, Chennai
Heat Load Estimations
LIGHTS
reason that for air-conditi oning, outdoor air is introduced which develops a positive pressure inside the
L ights produce sensible heat and are dissipated by
conditioned area and only exfiltration does occur.
radiation and convection. A bout 80% of the input
H owever i nfiltration may occur if wind velocity outside
is radiated and around 10% is convected for an
is higher. Infiltration is also a predominant feature for
incandescent lamp. For a fluorescent lamp 25% of
high ri se buildings due to stack effect. Infiltration of ai r
the input is radiated 50% is convected. For a
and by pass of air through the cooling coil becomes a
fluorescent lamp, approximately 25% more heat is
room load.
generated than the input and this is due to the ballast. It is preferred to get the exact number of
O utdoor ai r is introduced into the conditi oned area so
lights and its wattage and type. It is also a common
as to dilute the odoursgiven off by the people, smoking
practice to give this load in watts/ sq.ft depending
and other fumes and contaminations generated inside
on the application. T he wattage is multip lied by
the room. T he quantity of fresh air depends upon the
3. 413 to arrive at the heat dissipated in B T U / hr.
volume of the room or the number of people and the activity. V entilati on standardsfor different appli cations
ELECTRIC MOTORS
are shown i n the enclosed tabulations. For comfort applications during the peak load when i t is permi tted
Electric motors generate sensible heat which is
the outdoor air quantity may be reduced resulting in
dissipated inside the conditioned area depending
smaller equipment. H owever during periods other than
on the location of the prime mover and the driven
the peak load the required maximum fresh air has to
equi pm ent. T he heat dissi pated by the motor is
be introduced into the room which will do the flushing.
input multipli ed by the motor i nefficiency. T he rest
H owever i n any case the air quantity during peak load
of the heat is dissipated by the driven machinery.
should not be lesser than 50% of the required air
When a motor is overloaded or partially loaded the
quantity. Indoor air quality (IAQ) is now talk ed loudly
heat generated will not obey the above law. A s such
by all. M ini mum requirem ent of fresh air for
in case of heavy machinery load it is advisable to
applications having lesser occupancy is one air change
measure the input and not to depend on the rated
per hour.
horse power of the motors. When the motor rating is in K W i t is multip lied by 341 3 and when the
Solar gain through walls, glass, roof and transmission
rating is in H P it i s multiplied by 2545 to obtain
gain through partition walls, ceiling, floors, internal
the heat dissip ation i n B T U / hr. Suitable diversity
loads such as people, light, equi pm ent and
has to be applied to the connected electrical load
infiltration of fresh air(due to by pass in the cooling
depending on the actual running of the motor at a
coil) constitute R oom S ensible H eat (R SH ). When the
particular period of time.
system gai n is added to this, thi s becom es Effective R oom Sensible H eat (ER SH ).
O ther internal loads that may constitute the room load may be gas burners, electric/ steam heaters and
H eat gain through infiltration, people and other sources
water fountains, hot water/ steam pi pes and tanks.
which adds moisture in the room constitute Room L atent H eat (R L H ). W hen system gain is added it becomes Effective R oom L atent H eat (ER L H ). T he
SYSTEM HEAT GAIN
summ ation of room sensible / effective room sensible
System heat gain constitutes heat added or lost by
and room latent / effective room latent heat is called
the system components such as ducti ng, pi pi ng,
asR oom Total H eat (R T H )/ Effective R oom Total H eat
water pumps and the blower. O ver and above some
(ER T H ). When outdoor sensible and latent heat is added
safety factor is considered to account for the errors
it becomes G rand T otal H eat (G T H ) based on which
in the survey or i n the estimate. L eakage in the
the air-conditioning system is designed.
supply duct will add to the room sensible and latent heat. Supply ducts running in non conditioned area
T he effective room sensible heat over the effective
will gain heat and as such becomes the room sensible
room total heat is called as effective room sensible
load. R eturn ducts for the above reasons will add to
heat factor. With this factor and the inside design
the outdoor load.
conditions, A pparatus D ew P oint (A D P ) is calculated. D ew point i s the temperature at which condensation occurs when the air is cooled and the effective
INFILTRATION AND VENTILATION
surface temperature of the coil should match with the
Infiltration is not a feature for air-conditioning jobs
dew poi nt to meet the design parameters. T emperature
which is so for refri geration. T his is for the sim ple
rise is the difference in temperature between the room
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Ishrae Institute of Excellence, Chennai
Heat Load Estimations
and the apparatus dew point multiplied by the factor
otherwise will cause a cold blast on the occupants. T he
(1-bypass factor). Effective room sensible heat over
dehumidified air quantity and the bypassed air is the
1. 08 and the temperature rise gives the dehumidi fied
total air quantity on which the equipment is selected.
air quantity which has to be pumped into the room to
Similarly for applications such as clean rooms minimum
offset the room load and to meet the design conditions.
required air changes are required to be met. D uring such occasions also more air will be bypassed across
In high latent load applications the dehumidified air
the cooling coil.
quantity will work out to be low. In such cases some air has to be bypassed across the cooling coil to reduce the temperature of air entering the room which
A I R Q U A N T IT Y E Q U A T I O N S
D E R IV AT I O N O F A I R C O N S TA N T S
ERSH cf m da =
1 . 0 8 x (1 -BF)(t r m - t ad ) p
(1 )
1.08 = 0.244 x
60 13.5
where . 24 4 = specific heat of moist air at 70 F db and 50% rh, B tu/ (deg F) (lb dry air)
ERLH cf m da = . 6 8 x (1 -BF)(W r m - W ad ) p
60
(2 )
= m i n/ hr
13 . 5 =
specific volume of moist air at 70 F db and 50% rh
ERTH cf m da =
4 . 4 5 x (1 -BF)(h r m - h adp )
(3 )
T SH cf m da ‡ =
1 . 0 8 (t -t ) ed b l db
60 13. 5
0. 68 =
where 60
(4 )
13. 5
x
1076 7000
= m i n/ hr = specific volume of moist air at 70 F db and 50% rh
10 76 = average heat removal required to condense one pound of water vapor
T L H cf m da ‡ =
. 6 8 x (W - W l ) ea a
from the room air
(5 )
70 00 = grains per pound
G T H cf m da ‡ =
4 . 4 5 (h ea - h la )
(6 )
4.45 =
where 6 0
RS H cf m sa =
1 . 0 8 x (t -t ) r m sa
. 6 8 x (W - W sa ) r m
(7 )
70 F db and 50% rh
* RS H S, R L H S and G T H S are supplementary loads due to duct heat gain, duct leakage loss, fan and pump horsepower gai ns, etc. T o sim pli fy the various exam ples, these supplementary loads have not been used in the calculations. H owever, in actual practice, these supplementary loads should be used where appropriate.
(8 )
RT H cf m sa =
4 . 4 5 x (h r m - h sa )
cf m ba = cf m sa - cf m da
(9 )
‡ When no air i s to be physically bypassed around the conditioning apparatus, cfm da = cfmsa .
(10)
Not e: cfm da wil l be less th an cfm sa o n l y w h e n a i r i s physically bypassed around t he conditio nin g apparatus.
cf m sa = cf m o a + c f m r a
= m i n/ hr
13 . 5 = specific volume of moist air at
RL H cf m sa =
60 13.5
** When tm, Wm and hm are equal to the entering conditi ons at the cooli ng apparatus, they may be substituted for tedb, Wea and hea respectively.
(11)
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Ishrae Institute of Excellence, Chennai
Heat Load Estimations
Cooling & Dehumidifying Heat Load Estimate Estimated by :
D ate :
C heck ed by :
P age N o. :
Job N ame
E sti mated for
L ocal T i me
C O N D IT IO N S
DB
P eak L oad L O C A L T I M E SU N T I M E
A ddress Space U sed for
X
Size I tem
=
A rea or Q uanti ty
S q. Ft. X
=
Sun G ai n or T emp. D iff.
Factor
______ of ______
WB
% RH
DP
XXX
XXX
XX
G r/ L b
C u. Ft. B tu/ H our
O u tsi d e Room
S OLAR GAIN GLASS G lass
Sq Ft X
X
G lass G lass
Sq Ft X Sq Ft X
X X
G lass
Sq Ft X
X
Sk y light
Sq Ft X
X
D i fference
S elected R oom C ondi ti ons
DB
WB
% R H
VENTILATION P eople X C fm/ P erson= INFILTRATION Sq. Ft. X C fm/ sq. ft = C fm Ventilation *
S OLAR & TRANS . GAIN - WALLS & ROOF Wall
Sq Ft X
X
Wall
Sq Ft X
X
S WINGING/
Wall
Sq Ft X
X
R EV O L V IN G D O O R S - P EO P L E X
C FM / P ER SO N =
Wall
Sq Ft X
X
C FM / D O O R =
Wall
Sq Ft X
X
O pen doors Exhaust Fan C rack
R oof Sun
Sq Ft X
X
R oof Shaded S q Ft X
X
X Feet X
C fm/ Ft =
C F M O U T S ID E A I R T H R U A P P A R A T U S * SENSIBLE HEAT FACTOR & APPARATUS DEWPOINT
TRANS GAIN EXCEPT WALLS & ROO F A ll G lass
Sq Ft X
X
(A ) Eff. room Sens. H eat
P ar ti ti o n
Sq Ft X
X
(C ) Eff. room total Heat
C ei lli ng
Sq Ft X
X
Floor
Sq Ft X
X
( 1-B F ) X
INFILTRATION AND OUTSIDE AIR I nfi ltr ati on
C fm X
O utsi de A i r
C fm X
X 1. 08 °
F X
NOTES
P eople
X
P ower
H .P./ K W
X
L I ghts
W atts
X 3. 4 X 3. 4 X
ROOM SENSIBLE HEAT S upply
S upply
F an
D uct
D uct
H . P. % Factor
H eat G ai n%
L eak L oss%
S af et y
EFFECTIVE ROOM SENSIBLE HEAT (A) ROO M LATENT H EAT I nfi ltrati on
C fm X
gr/ lb X
0. 68
O utsi de-A i r
C fm X
gr/ lb X
B F X 0. 68
P eople X
S team A ppliances, Etc
lb/ hr X 1080
Vapor Tran. R oom L atent H eat SubT otal SU P P LY D U C T L EA K A G E L O S S
% + SA FET Y FA C T O R %
EFFECTIVE ROOM LATENT HEAT (B) EFFECTIVE ROOM TOTAL HEAT (C)=(A+B) S ensi ble: L atent:
O U T S ID E A I R H E A T ° C fm X F X C fm X gr/ lb X
G ra n d To t a l He a t S u b -To t a l
R etur n D uct H eat G ai n%
GRAND TO TAL HEAT (GTH)
(1-BF) X 1.08 (1-B F) X 0. 68
( D ) = (C + O u t s i d e A i r H e a t )
R etur n D uct L eak L oss
P um p H . P. % (E)
=
1.08 X D ehumidified rise
INTERNAL HEAT P eople
P eople
F Selected A D P
( R oo m T em p-A D P ) =
R oom Sensible heat
BF X 1.08
A ppli ances, E tc
°
Indicated A D P
%
= (D +Lo ss es )
To n s = E / 1 2 , 0 0 0
7
=
(ESH F) Sens H eat Factor °
F
D ehum idi fi ed ri se ° F D ehumidified C FM
DISCLAIMER
Ishare Foundation Trust, Bangalore and IIE Bangalore confirm that the materials are compiled from various lectures, seminars, workshops conducted by various ISHRAE members, faculties of repute from ISRHAE Bangalore Chapter. This is not a book but a collection of course materials to refresh and train the freshers and others belonging to the HVAC & R and allied fraternity.
