CoolingandHeatingLoadEstimation：加热和冷却负载的估计课件.ppt

1、Cooling and Heating Load EstimationA Trane Air Conditioning Clinic American Standard Inc.2000Air Conditioning Clinic TRG-TRC002-ENperiod oneHuman Comfort American Standard Inc.2000Air Conditioning Clinic TRG-TRC002-ENCooling and Heating Load EstimationAir Conditioning Clinic TRG-TRC002-EN American S

2、tandard Inc.2000Principles of Heat TransfersHeat energy cannot be destroyedsHeat always flows from a higher temperature substance to a lower temperature substancesHeat can be transferred from one substance to anotherAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Methods of Heat Tran

3、sferradiationhotwaterconductionconvectioncool airwarm airAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Measuring Heat QuantityAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Sensible versus Latent HeatAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000H

4、eat Generated by PeopleAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Surrounding Air ConditionsAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Factors Affecting Human ComfortsDry-bulb temperaturesHumiditysAir movementsFresh airsClean airsNoise levelsAdequate lightin

5、gsProper furniture and work surfacesAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Indoor Design ConditionsA Aperiod twoCooling Load Estimation American Standard Inc.2000Air Conditioning Clinic TRG-TRC002-ENCooling and Heating Load EstimationAir Conditioning Clinic TRG-TRC002-EN Ame

6、rican Standard Inc.2000Cooling Load ComponentsAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Cooling Load Componentssensibleloadlatentloadconduction through roof,walls,windows,and skylightssolar radiation through windows,skylightsconduction through ceiling,interior partition walls,a

7、nd floorpeoplelightsequipment/appliancesinfiltrationventilationsystem heat gainsspaceloadcoilloadcooling load componentsAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Time of Peak Cooling Loadheat gain12612612noona.m.p.m.midmidAir Conditioning Clinic TRG-TRC002-EN American Standard

8、Inc.2000Example Office Space(Room 101)Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Outdoor Design ConditionsSt.Louis,MissouriDBWBDBWBDBWB0.4%1%2%95F35C76F25C93F34C75F24C90F32C74F23CAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Heat Conduction through SurfacesAir

9、Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Conduction through a Shaded WallQ =U A TAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000U-factorAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000U-factor for Example Wallthermal resistance(R)Routdoor-air film0

10、.25 0.04Rsiding0.61 0.11Rconcrete block2.00 0.35Rinsulation13.00 2.29Rgypsum board0.45 0.08Rindoor-air film0.68 0.12Rtotal16.99 2.99U =Rtotal1U =0.06 Btu/hrft2F U =0.33 W/m2K Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Conduction through a Shaded WallQwall=0.06 380 (95 78)=388 Bt

11、u/hr Qwall=0.33 36.3 (35 25.6)=113 W Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Sunlit SurfacesAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Time Lagsolar effect12612612noona.m.p.m.midmidABAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Q =U A C

12、LTDConduction through Sunlit SurfacesAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000CLTD Factors for West-Facing Wallhour21 17 14 11 8 7 667CLTD(F)35 30 256 7 8 9 10 11 121234513 14 15 1618 191720 21 22 23 24CLTD(C)8 10 12 16 22 30 37 44484845 4112 9864 4 33419 17 14467 9 12 17 21 2

13、4272725 23Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Conduction through Sunlit SurfacesQwall=0.06 380 22=502 Btu/hrQroof=0.057 2,700 80=12,312 Btu/hr Qwall=0.33 36.3 12=144 W Qroof=0.323 250.7 44=3,563 W Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000U-factors f

14、or Windowsfixed frames,vertical installationsingle glazing 1/8 in.3.2 mm glassdouble glazing 1/4 in.6.4 mm air space1/2 in.12.8 mm air space1/4 in.6.4 mm argon space1/2 in.12.8 mm argon spacetriple glazing 1/4 in.6.4 mm air spaces1/2 in.12.8 mm air spaces1/4 in.6.4 mm argon spaces1/2 in.12.8 mm argo

15、n spaces1.13 6.42aluminum without thermal breakwood/vinyl0.69 3.940.64 3.610.66 3.750.61 3.470.49 2.760.55 3.10aluminum with thermal break0.47 2.660.51 2.901.07 6.070.63 3.560.57 3.220.59 3.370.54 3.080.42 2.390.48 2.730.40 2.300.45 2.540.98 5.550.56 3.170.50 2.840.52 2.980.48 2.700.35 2.010.41 2.33

16、0.34 1.910.38 2.15Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Conduction through WindowsQwindows=0.63 160 13=1,310 Btu/hr Qwindows=3.56 14.4 7=359 W Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Solar Radiation through GlassAir Conditioning Clinic TRG-TRC002-EN

17、American Standard Inc.2000Solar Radiation through GlassQ =A SC SCLAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Solar Cooling Load FactorsDirection that the window facessTime of daysMonthsLatitudesConstruction of interior partition wallssType of floor coveringsExistence of internal

18、 shading devicesAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Shading Coefficientshading coefficient at normal incidenceuncoated single glazing 1/4 in.6.4 mm clear1/4 in.6.4 mm greenreflective single glazing 1/4 in.6.4 mm SS on clear1/4 in.6.4 mm SS on greenuncoated double glazing

19、1/4 in.6.4 mm clear-clear1/4 in.6.4 mm green-clearreflective double glazing 1/4 in.6.4 mm SS on clear-clear1/4 in.6.4 mm SS on green-clear0.82aluminum frame other framesoperable fixed0.850.690.820.590.610.490.590.260.280.220.250.260.280.220.250.700.740.600.700.480.490.400.470.180.180.150.160.200.180

20、.150.17SS=stainless-steel reflective coatingoperable fixedAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Solar Radiation through WindowsQwindows=160 0.74 192=22,733 Btu/hr Qwindows=14.4 0.74 605=6,447 W Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Shading DevicesA

21、ir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Internal Heat GainsAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Heat Generated by Peoplemoderately active work(office)sensibleheat gain250 Btu/h75 Wlatentheat gain200 Btu/h55 Wlevel of activitystanding,light work,or wa

22、lking(store)250 Btu/h75 W200 Btu/h55 Wlight bench work(factory)275 Btu/h80 W475 Btu/h140 Wheavy work(factory)580 Btu/h170 W870 Btu/h255 Wathletics(gymnasium)710 Btu/h210 W1,090 Btu/h315 WAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000CLF Factors for Peoplehours after people enter sp

23、ace0.11 0.08 0.06 0.05 0.04 0.03 0.02 0.02 0.010.65 0.74 0.16678910111212345total hours in space2468100.650.650.650.650.85 0.24 0.17 0.13 0.10 0.07 0.06 0.04 0.030.75 0.810.85 0.89 0.91 0.29 0.20 0.15 0.12 0.09 0.070.75 0.810.85 0.89 0.91 0.93 0.95 0.31 0.22 0.17 0.130.810.750.85 0.89 0.91 0.93 0.95

24、 0.96 0.97 0.33 0.240.810.75Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Heat Gain from PeopleQsensible=18 250 1.0=4,500 Btu/hrQlatent=18 200=3,600 Btu/hr Qsensible=18 75 1.0=1,350 W Qlatent=18 55=990 W Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Heat Gain from

25、 LightingQ=watts 3.41 ballast factor CLF Q=watts ballast factor CLF Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Heat Gain from LightingQlights=5,400 3.41 1.2 1.0=22,097 Btu/hr Qlights=5,400 1.2 1.0=6,480 W Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Heat Gener

26、ated by Equipmentcoffee makersensibleheat gain3,580 Btu/h1,050 Wlatentheat gain1,540 Btu/h450 Wequipmentprinter(letter quality)1,000 Btu/h292 Wtypewriter230 Btu/h67 WAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000InfiltrationAir Conditioning Clinic TRG-TRC002-EN American Standard In

27、c.2000Methods of Estimating InfiltrationsAir change methodsCrack methodsEffective leakage-area methodAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Infiltration Airflowinfiltration airflow32,400 0.360=162 cfm infiltration airflow927.6 0.33,600=0.077 m3/sAir Conditioning Clinic TRG-T

28、RC002-EN American Standard Inc.2000Heat Gain from InfiltrationQsensible=1.085 airflow TQlatent=0.7 airflow W Qsensible=1,210 airflow T Qlatent=3,010 airflow W Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Heat Gain from InfiltrationQS=1.085 162 (95 78)=2,988 Btu/hr QS=1,210 0.077 (

29、35 25.6)=876 W QL=0.7 162 (105 70)=3,969 Btu/hr QL=3,010 0.077 (15 10)=1,159 W Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000sensible loadBtu/hr Wconduction through roofsolar radiation through windowspeoplelightsequipmentinfiltrationconduction through windowsconduction through exte

30、rior wall12,312 3,5634,500 1,35022,097 6,4808,184 2,4042,988 87674,626 21,623total space cooling load3,600 9901,540 4503,969 1,159latent loadBtu/hr W9,109 2,599space load components502 1441,310 35922,733 6,447Summary of Space Cooling LoadsAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2

31、000VentilationAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Outdoor Air Requirementsauditoriumoutdoor air(per person)15 cfm0.008 m3/stype of spacelocker roomsoffice spacepublic restroomssmoking lounge0.5 cfm0.0025 m3/s20 cfm0.01 m3/s50 cfm0.025 m3/soutdoor air(per ft2 m2)classroom1

32、5 cfm0.008 m3/s60 cfm0.03 m3/sAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Cooling Load Due to Ventilation QS=1.085 360 (95 78)=6,640 Btu/hrQL=0.7 360 (105 70)=8,820 Btu/hr QS=1,210 0.18 (35 25.6)=2,047 W QL=3,010 0.18 (15 10)=2,709 W Air Conditioning Clinic TRG-TRC002-EN American

33、 Standard Inc.2000System Heat GainsAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Components of Fan HeatAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Heat Gain in DuctworkAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000sensible loadBtu/hr Wconductio

34、n through roofsolar radiation through windowspeoplelightsequipmentinfiltrationconduction through windowsconduction through exterior wall4,500 1,35022,097 6,4808,184 2,4042,988 876total space cooling load3,600 9901,540 4503,969 1,159latent loadBtu/hr W9,109 2,599502 1441,310 35922,733 6,447ventilatio

35、n6,640 2,0478,820 2,70981,266 23,670total coil cooling load17,929 5,308Summary of Cooling Loads12,312 3,56374,626 21,623period threePsychrometric Analysis American Standard Inc.2000Air Conditioning Clinic TRG-TRC002-ENCooling and Heating Load EstimationAir Conditioning Clinic TRG-TRC002-EN American

36、Standard Inc.2000Space Load versus Coil Loadspaceloadcoilloadconduction through roof,walls,windows,and skylightssolar radiation through windows,skylightsconduction through ceiling,interior partition walls,and floorpeoplelightsequipment and appliancesinfiltrationventilationsystem heat gainsAir Condit

37、ioning Clinic TRG-TRC002-EN American Standard Inc.2000Space Sensible and Latent Loadssensible loadBtu/hr Wconduction through roofsolar radiation through windowspeoplelightsequipmentinfiltrationconduction through windowsconduction through exterior wall12,312 3,5634,500 1,35022,097 6,4808,184 2,4042,9

38、88 87674,626 21,623total space cooling load3,600 9901,540 4503,969 1,159latent loadBtu/hr W9,109 2,599space load components502 1441,310 35922,733 6,447Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Sensible Heat Ratio(SHR)SHRsensible heat gainsensible heat gain+latent heat gain=0.89

39、74,62674,626+9,109SHR=0.8921,62321,623+2,599SHR=Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Single-Space AnalysisspaceAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Determine Supply Airflowsensible heat gainsupplyairflow=1.085 (room DB supply DB)sensible heat gai

40、nsupplyairflow=1,210 (room DB supply DB)Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Determine Supply Airflow74,6262,990 cfm=1.085 (78 55)supplyairflow=21,6231.40 m3/s=1,210 (25.6 12.8)supplyairflow=Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Calculate Entering

41、 Coil Conditionsventilation airflow%outdoor air =total supply airflow 360 cfm%OA =2,990 cfm=0.120.18 m3/s%OA =1.40 m3/s=0.12Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Calculate Entering Coil ConditionsB BA AC C95F 0.12 =11.4F 78F 0.88 =68.6Fmixture =80.0F35C 0.12 =4.2C 25.6C 0.8

42、8 =22.5Cmixture =26.7CAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Determine Supply Air TemperatureD DB BA AC CAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Recalculate Supply Airflow21,6231.69 m3/s=1,210 (25.6 15)supplyairflow=74,6263,620 cfm=1.085 (78 59)supply

43、airflow=Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Room 101Btu/hr Wtotal coil cooling load99,195 28,978ventilation15,460 4,756Total Cooling Load on Coiltotal space sensible load9,109 2,59974,626 21,623total space latent loadAir Conditioning Clinic TRG-TRC002-EN American Standard

44、 Inc.2000Multiple-Space AnalysisAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Room 101(Faces West)8 a.m.Btu/hr Wconduction through roofsolar radiation through windowspeoplelightsequipmentinfiltrationconduction through windowsconduction through exterior wall160 482,616 740202 513,55

45、2 1,0124,500 1,35022,097 6,4808,184 2,4042,988 87644,299 12,961total space sensible load4 p.m.Btu/hr W4,500 1,35022,097 6,4808,184 2,4042,988 876space sensible loadcomponents74,626 21,623502 1441,310 35922,733 6,44712,312 3,563Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Room 102(

46、Faces East)8 a.m.Btu/hr Wconduction through roofsolar radiation through windowspeoplelightsequipmentinfiltrationconduction through windowsconduction through exterior wall160 4821,667 6,1384,500 1,35022,097 6,4802,988 87662,414 18,087total space sensible load4 p.m.Btu/hr W844 2521,310 3593,078 8744,5

47、00 1,35022,097 6,4802,988 87655,313 16,158202 51space sensible loadcomponents8,184 2,4048,184 2,4042,616 74012,312 3,563Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000“Sum-of-Peaks”versus“Block”Room 101(faces west)Room 102(faces east)space sensible loadsum-of-peaks=74,626+62,414=137

48、,040 Btu/hr 21,623+18,087=39,710 Wblock=74,626+55,313=129,939 Btu/hr 21,623+16,158=37,781 W8 a.m.Btu/hr W4 p.m.Btu/hr W44,299 12,96174,626 21,62362,414 18,08755,313 16,158Air Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000“Sum-of-Peaks”versus“Block”sSum-of-peakssupply airflow=6,648 cfm

49、3.10 m3/ssBlocksupply airflow=6,303 cfm 2.95 m3/sAir Conditioning Clinic TRG-TRC002-EN American Standard Inc.2000Room 101Btu/hr Wtotal coil cooling loadRoom 102Btu/hr W99,195 28,978ventilation15,460 4,756“Block”Cooling Load79,882 23,51315,460 4,756total space sensible load9,109 2,59974,626 21,623tot

50、al space latent load55,313 16,1589,109 2,599block cooling load(4 p.m.)=99,195+79,882=179,077 Btu/hr 28,978+23,513=52,491 Wloads at 4 p.m.period fourHeating Load Estimation American Standard Inc.2000Air Conditioning Clinic TRG-TRC002-ENCooling and Heating Load EstimationAir Conditioning Clinic TRG-TR