ASHRAE.4431-2001 Effect of 1997 Handbook Summer Design Temperature

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1、4431Effectof1997HandbookSummerDesignTemperatureSpecificationsonEnthalpyandHumidityRatioJamesW.Stevens,Ph.D.,P.E.MemberASHRAEABSTRACTspecifications.TheHandbookdescribestheapplicabilityofthethreespecificationsasfollows:Thepurposeofthispaperistoprovideaquantitativeover-alldescriptionofth

2、edifferencesinhumidityratioandenthalpy“[db-mwb]oftenrepresentconditionsonhot,mostlysunnythatareassociatedwiththenewextremeweatherspecifica-days.Theseareusefulforcoolingapplications,especiallyair-conditioning...[wb-mdb]representextremesofthetotaltionspresentedinthe1997ASHRAEHandbook—Fu

3、ndamen-sensiblepluslatentheatofoutdoorair.Thisinformationistalsascomparedtothetraditionalweatherdataspecification.usefulforcoolingtowers,evaporativecoolers,andfreshairDifferencesbetweenthenewspecificationsandthetraditionalventilationsystemdesign...[dp-mdb]aredirectlyrelatedtospecifica

4、tionarepresentedforthe0.4%annualfrequencyofextremesofhumidityratio,whichrepresentpeakmoistureoccurrencedata.Theeffectofpopulationdistributionandtheloadsfromtheweather.Extremedew-pointconditionsmay2.0%annualfrequencyofoccurrenceareexamined.Bothoccurondayswithmoderatedry-bulbtemperature

5、sresultingspecificationsresultinanincreaseinthetotalenthalpyforinhighrelativehumidity.Thesevaluesareespeciallyusefulmostlocations.For85%-86%percentoflocations,thisforapplicationsinvolvinghumiditycontrol,suchasdesic-increasewasintherangeof0-4Btu/lbm(0-9.3kJ/kg).Forcantcoolinganddehumid

6、ification,cooling-baseddehumid-da11%oflocations,thedew-pointspecificationresultsinalowerification,andfreshairventilationsystems.Thevaluesareenthalpythanthetraditionaldry-bulbspecification.For47%alsousedasacheckpointwhenanalyzingthebehaviorofcoolingsystemsatpartloadconditions,particula

7、rlywhenofalllocations,thedew-pointspecificationresultsinahumid-suchsystemsareusedforhumiditycontrolasasecondaryityratiomorethan30grains/lbmda(4.3g/kg)higherthanthatfunction.”ofthedry-bulbspecification.The1997Handbookpresentedalltemperaturespecifica-INTRODUCTIONtionsinaslightlydifferen

8、tform