Under floor Radiant system
Human Comfort Zone: Combination of 50% radiation, 30% convection and 20% evaporation. Temperature range: 2020-26 C˚ (68˚(68˚-78˚F) Relative humidity range: 3030-60% Air movement velocities: 0.150.15-0.25 m/s Surface to Air temperature difference ≤ 2˚ C (4˚F)
Limitations of Conventional AllAll-Air HVAC System Comfort and Indoor Air Quality • Uneven space comfortcomfort-cost of control zones • High air velocitiesvelocities-typically≥0.3 m/s (50(50-100 fpm) • Portion of contaminated air is mixed and rere-circulated • Potentially high noise and draft levels Cost • Large equipment capacities requirements • Moving Large air volumes=energy intensive operation • Higher mechanical equipment and building space cost • Large space requirements
What is Radiant Cooling ?
Principal
Application
Radiant System Condition People …. Not Building
What's the Radiant Cooling Concept • Cooling in summer (absorber), Heating in winter (emitter) • Radiant cooling supplements airside system • Cooling medium warm 16° 16°C to 22° 22°C (61° (61°F to 72° 72°F) • Heating medium cool at 30° 30°C to 40° 40°C (86° (86°F to 104° 104°F) • Well suited to alternative energy sources due to moderate temperatures.
Cost Advantages – Radiant System • Smaller, More Efficient Chillers • Testing and Balancing Made Simpler • Reduced Maintenance Cost & Operating Cost • Not paying for Over Ventilating • Piping is not insulated • Reduced Sprinkler Piping • Reduce Fan Energy
What's the Attraction –Radiant System •Aesthetic benefits - clean space • Better acoustics & Comfort • Facilitates decoupling cooling and ventilation • Works well with Displacement or UFAD • Improved plant efficiency • Shaves off peak load /Reduce Plant Installed capacity • Cascade loads • Geothermal and aquifer cooling • Evaporative cooled • Can reduce construction time/cost • Simplified controls • Reacts to direct solar loads •Fits well with Thermally Active Buildings and Green Buildings
Benefit Features of Radiant System • Zoning capabilitiescapabilities- Increase staff productivity • No Noise, No draft • No plenumplenum- increase height up to one ft. of space ea. floor • Save energy up to 50% • Maintenance one Pump!Pump!-Only Ventilation requires servicing • Indoor Air Quality • Radiant Cooling & Heating simultaneously (north & south) • Utility room require less space
Figure shows how radiant cooling systems achieve savings. The graphic breaks out the components of peak HVAC energy use in office buildings for a conventional system and for a radiant cooling system that uses water as an energy transport medium. About 62.5 percent of the conventional system’s energy use consists of cooling load that the chiller must remove. Virtually all of the remaining power demand is used for air transport, and radiant cooling can eliminate most of that. As a consequence, in the example in the figure, energy savings is greater than 42 percent. In areas with high humidity during the cooling season, the savings are proportionally less.
Source: LBNL
Design Methodology :
Source: Robert Bean - Ishrae
Design Methodology :
Effect on Radiant Output by varying different parameters
Operative Temp. -Uniform temp of an enclosure in which Occupant would exchange the same Amount of heat by radiation plus convection as In nonnon-uniform environment
Combined Radiant and Convective Heat Transfer Mean panel temperature
Room temperature
°F (°C)
°F (°C)
Q radiation Btu/h·ft² (W/m2)
Q convection Btu/h·ft² (W/m2)
Q total Btu/h·ft² (W/m2)
U, overall HT coeff, Btu/h·ft² ·°F (W/m2 ·°C)
50 (10)
72 (22)
19 (60)
18 (57)
37 (117)
1.66 (9.43)
55 (13)
72 (22)
15 (47)
13 (41)
28 (88)
1.61 (9.14)
60 (16)
72 (22)
11 (35)
8 (25)
19 (60)
1.54 (8.75)
65 (18)
72 (22)
6 (19)
4 (13)
10 (32)
1.45 (8.23)
50 (10)
78 (26)
24 (76)
24 (76)
48 (151)
1.73 (9.82)
55 (13)
78 (26)
20 (63)
19 (60)
39 (123)
1.7 (9.65)
60 (16)
78 (26)
16 (51)
14 (44)
30 (95)
1.65 (9.37)
• The greater the difference between the mean panel temperature and the room temperature, the greater the heat transfer • Even though the radiant heat transfer is highly nonlinear, the overall U-factors are relatively constant in the ranges of temperatures presented
Radiant Floor Design
• In direct sun - solar cooling can reach 100to150W/m2
Radiant Ceiling Design
Cooing Mode
Heating Mode
• In direct sun - solar cooling can reach 100to150W/m2
Energy Consumption Characteristics of Commercial Building HVAC
Source: Dr.James Brodrick- Ishrae
Minimum Temp for cooing/Maximum Temp for Heating – Various Surface
Output of Radiant Cooling / Heating – Various Surface
Heat Load Analysis SR. NO.
DISCRIPTION
DEHUMID AREA IFIED (SQ. FT.) CFM
TR
NO. EQP. OCCU OF PC LOAD FRESH LOAD . PC (WATTS) AIR WATTS
GROUND FLR TOTAL
10447
28751
82.25
329
84
12600
3284
FIRST FLR TOTAL
9643
15033
46
215
107
16050
2310
SECOND FLR TOTAL
8765
22421
54
208
98
14700
1832
GRAND TOTAL
28855
66205
183
752
289
43350
7426
69800
Radiant Radiant Radiant Total
TR
TR
TR
TR
TR
TR
Recommanded Dem.CF TR M
350346 117766 142668 82927
39.0 18.8
29.2 11.9
9.8 6.9
9.6 2.8
18.2 5.3
27.8 8.1
45.55 20
15204 5622
493014 200693
57.8
41.1
16.7
12.4
23.5
35.9
65.3
20826.0
184709 63602 171358 59445
20.7 19.2
15.4 14.3
5.3 5.0
5.6 5.9
10.5 11.2
16.1 17.1
22 25
7899 7134
356067 123047
40
30
10
11
22
33
46
15033
187514 54767 218040 83376 92811 0
20.2 25.1 7.7
15.6 18.2 7.7
4.6 6.9 0.0
4.8 5.2 0.4
9.0 9.8 0.8
13.8 15.1 1.3
21 26 8
8123 9003 5295
498365 138143
53.0
41.5
11.5
10.4
19.7
30.1
53.9
22421.0
1809329 1347446 461883
151
112
38
34
65
99
166
58280
BTU Gr.Floor AHU-1 468112 AHU-2 225595 Grand Total 693707 First Floor AHU - 1 248311 AHU - 2 230803 Grand Total 479114 Second Floor AHU -1 242281 AHU -2 301416 AHU -3 92811 Grand Total 636508 Total Building
Sensible Latent BTU
BTU
Total
Sensible Latent
Floor
Ceiling
Total
For Area of 28,855 Sq.Ft –Air conditioning Req Req–– 183 TR & 66,205 CFM (Less) Sensible load of building catered with Radiant Floor (34 TR) + Ceiling (65 TR) = 99 TR Radiant Balance TR Required 84 TR & 36505 CFM Conclusion : Reduction in Plant & Air distribution - Reduction in Capital Cost Radiant Chiller operates at higher leaving temp i.e.16° i.e.16° C –More Efficient chiller Water Velocity in Radiant Pipes are less compared to conventional system – Less Pump power & presssure drop
Initially Power required = 66205 x 4.5 (2.5 inch + 2 inch AHU loss) 6356 x 0.75 (Fan effiency considered 75 %) x 0.85 motor Effencey With Radiant = 36505 x 4.5 = 40 KW 6356 x 0.75 x 0.85 So Saving in AHU motor power is 35 KW x 10 Hr x 365 x 5.5 Rs/KW = 7,02,625 Rs /year
= 75 KW
Power Saving in AHU – Operational Cost Conventional AHU Power input
75 KW
With Radiant – Reduced AHU input
35 KW
Saving AHU Power 40 KW In terms of cost Saving in AHU motor power is = 40 KW x 10 Hr x 365 x 5.5 Rs/KW = 8,03,000 Rs /year
Power Saving in Chillers – Operation cost Conventional Chiller Water Temp i.e. 7 – 12 ° C Power input = 150 KW With Radiant Chiller Water Temp i.e. 1616- 21 ° C–Power input = 50 KW+ Balance Conventional Chiller Power Input = 55 KW Saving Chiller Power In terms of cost Saving in AHU motor power is = 45 KW x 10 Hr x 365 x 5.5 Rs/KW = 9,03,375 Rs /year
45 KW
For Area of 28,855 Sq.Ft –Air conditioning Req Req–– 183 TR & 66,205 CFM Since we will install Radiant System to take care of Sensible Load of Building With Radiant Floor (34 TR) + Ceiling (65 TR) = 99 TR Radiant By Radiant System following additional capital cost saving More space between floor to false ceiling height i.e. 1 ½ feet. ducting cost will be saved i.e 65 Sq.ft / TR x 99 TR (Radiant ) x 60 per Sq.ft = 3,86,100 + 1,00,000 (Supply & Return Grill) Reduce SITC cost for 99 TR i.e. chilled water piping,insulation etc = 60,000 Per TR x 99 Tr = 6,53,400
TR Capital Cost Payback Calculation Chiller + AHU System 183 10980000 (a) Radiant System – Ceiling (65 TR) – Area 28855 Sq.ft 28855 8584363 Radiant System – Floor (34 TR) 28855 4905350 Chiller for Radiant System 99 1980000 Balance - 84 TR With conventional Chiller + AHU 84 5040000 20509713 (b) (a) Additional cost 9529713 (b) Saving in AHU + Chiller power 1706375 Saving in Maintenance of Chiller & AHU 44000 Payback Period 5.4 Years
System peculiarities
System Functions
Technical Advantage of Pex
Polyethylene cross linked – Joint Less System Tested at 60 Bar pressure ,also pass ASTM Standard Flexible piping –No Joint behind the wall /flooring Available in 100 / 240 meter coil Light Weight - 7 kgs for 100mts approx. Separate Pipe for each circuit Easy transportable anywhere at sight Thickness: 1.78mm – 3.18 mm Connection with Manifold Compression type Life of Pipe is appropriate for 50 years Maximum working temperature 100 °C Elasticity 300 – 500 % at 23° C Sizes – 3/8 “ ,1/2” ,3/4 “ & 1 “
Advantages of PEX Pipe Lack of incrustation
– Pipe remain Clean for longer period, even when it’s not in use Low noise - Systems have a high level of acoustic protection ,no turbulences in the flow. Saving time & money - Time needed is less than one required for an other system. System with total guarantee - To have perfect consistency and maximum sealing.
Technical data of PEX Pipe
System Installation : plan
Design and calculations
13 10
63 mm 40
Lateral view of the floor section
Lay insulation
Cover with Layout guide
Accessories to lay the pipes
Lay the pipes on K 389
Lay the pipes on K 389
Use of R 549 to avoid sharp bend
Cover the pipes with K393
Screed over the Metal net
Manifolds for the system
Controller (master)
Thermoregulation with bus system The system collects the data (temperature and relative umidity) The delivery temperature is chosen according to the room conditions in order to grant the maximum power output avoiding condensation
Primary bus
Secondary bus
------
I/O Unit (slave) K481 #1
K481 #2
K481 #3
K481 #8
Effect on Panel surface temperature based on method of installation
Case Study – Food Court Area , Malad
Case Study – Malad – Food Court Area
Radiant Under Floor Circuits
Area : 3342 Sq.Ft ( 311 Sq.Mtr)
Case Study– Malad – Food Court Area Circuit - 1 Manifold
Area : 3342 Sq.Ft ( 311 Sq.Mtr) – Circuit – PEX Pipe Circuit 1 Length – 332 Ft & Manifold Location near Column
Case Study – In Orbit – Malad – Food Court Area
Type of Radiant Inside system Water Temp. C Temp (Water Through PEX Pipe) In Out C
RH
Capacity
Area
Total
Budgetary Cost
Rs
%
watts/sqm
sqm
Capacity Tr
Under floor
18
21
24
65
41
311
3.63
7,00,000.00
Under floor
23
26
28 - 29
70
19
311
1.68
5,00,000.00
Capacity = 8.92 x (Ѳi – Ѳf,m)ⁿ where n=1.1 Ѳi = Temperature nominal indoor operative Ѳf,m = Average surface temperature 1 ) inside design temperature of 24 C operative temperature is 25 C and surface temperature when water in / out 18 / 21 is 21C Capacity = 8.92 x (4)ⁿ = 41 watts per sqm 2) Incase of 23 C water in out will be 27C surface temperature 27C and inside temperature = 29 C Capacity = 8.92 x (2)ⁿ = 19 watts per sqm
Case Study – In Orbit – Malad – Food Court Area
Radiant Capacity (W / Sq.Mtr)
Radiant Capacity with Chilled Water In 18 °C & Out at 21°C 200 180 160 140 120 100 80 60 40 20 0
watts/sqm
35 34 33 32 31 30 29 28 27 26 25 24 23 Room Ambient
Note : Considering Dew Point of Area is below 18 °C
Case Study – In Orbit – Malad – Food Court Area TEMPERATURE TEST (Cooling)
26°C in Conditioned Enviorment 25.5 °C
23.5 °C 22.5 °C
KD300 ENG.ppt
3m
21.5 °C 2m
1.5 m
19.5 C Floor 1m
54
Case Study – In Orbit – Malad – Food Court Area
System Component
Primary Piping
Secondary Piping
Control System
Case Study – In Orbit – Malad – Food Court Area Primary Pipings PIPE IN GIACOTHERM linked polyethylene BAO - 17x2 PLASTIC RAIL TO FIX PIPE
FLAT INSULATION ROLLS IN H30-2 (CONF.10m2)
Clips Fissatubo
INSULATION STRIP
Electro welded net
Case Study – In Orbit – Malad – Food Court Area Secondary Piping Pre-assembled manifolds DISTRIBUTION Pre-assembled manifolds DISTRIBUTION ADAPTERS CHROME BALL VALVE - FEMALE COUPLING - 1 " BOX FOR COLLECTORS - 800x460x110mm NC 230 VOLT ELECTRIC HEAD WITH MICRO-R473M Zone Valve - 3 Way Actuator Driven, with bypass, adjustment lockshield valves & tail Piece INTERMEDIATE CONNECTOR FOR COLLECTORS - 1 "
Case Study – In Orbit – Malad – Food Court Area Controls System BUS-K483A ROOM THERMOSTAT RELAY WITH TEMPERATURE AND % RH SENSOR OTSIDE TEMPERATURE SENSOR UNIT KPM20
K297 - PISTON mixing valve - DN50 - 40 Kv ENGINE WITH MANUAL CONTROL VALVE. MIXING K297 NETWORK CONTROLLER WITH PRIMARY BUS DELIVERY TEMPERATURE SENSOR POWER CONTROL SYSTEMS FOR A FLOOR TEMPERATURE CONTROLLED DELIVERY AND ENVIRONMENT DISPLAY UNIT TO CHECK PARAMETERS OF THE SYSTEM
Case Study – In Orbit – Malad – Food Court Area
Exclusions
1 2 3 4
High side - Chillers, and piping from chiller to radiant system piping header. Electrical works - Power supply to the manifolds. PHE (If existing Chiller available) & Chilled water pipe connection up to Manifolds Any control Mechanical / Electrical to regulate PHE out put i.e. Chilled water
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