ASHRAE.HandBook_39-2008 COOLING TOWERS

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1、RelatedCommercialResourcesCHAPTER39COOLINGTOWERSPrincipleofOperation.............................................................39.1Application...............................................................................39.7DesignConditions.....................................

2、...............................39.2PerformanceCurves...............................................................39.13TypesofCoolingTowers..........................................................39.2CoolingTowerThermalPerformance....................................39.15Materia

3、lsofConstruction........................................................39.7CoolingTowerTheory............................................................39.15SelectionConsiderations.........................................................39.7TowerCoefficients....................

4、..............................................39.17OSTair-conditioningsystemsandindustrialprocessesgen-Fig.1TemperatureRelationshipBetweenWaterandAirinMerateheatthatmustberemovedanddissipated.WaterisCounterflowCoolingTowercommonlyusedasaheattransfermediumtoremoveheatfromrefrigera

5、ntcondensersorindustrialprocessheatexchangers.Inthepast,thiswasaccomplishedbydrawingacontinuousstreamofwaterfromautilitywatersupplyoranaturalbodyofwater,heatingitasitpassedthroughtheprocess,andthendischargingthewaterdirectlytoasewerorreturningittothebodyofwater.Waterpur-chasedfro

6、mutilitiesforthispurposehasnowbecomeprohibitivelyexpensivebecauseofincreasedwatersupplyanddisposalcosts.Similarly,coolingwaterdrawnfromnaturalsourcesisrelativelyunavailablebecausetheecologicaldisturbancecausedbytheincreasedtemperatureofdischargewaterhasbecomeunacceptable.Air-cool

7、edheatexchangerscoolwaterbyrejectingheatdirectlytotheatmosphere,butthefirstcostandfanenergyconsumptionofthesedevicesarehighandtheplanarearequiredisrelativelylarge.Theycaneconomicallycoolwatertowithinapproximately11Koftheambientdry-bulbtemperature—toohighforthecoolingwaterrequirem

8、entsofmostrefrigerationsystemsandmanyind