ASHRAE.4447-2001 The Nulling Test A New Measurement Technique

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1、4447TheNullingTest:ANewMeasurementTechniqueforEstimatingDuctLeakageinResidentialHomesPaulW.FranciscoLarryS.PalmiterMemberASHRAEABSTRACTefficiencyisleakage.Unfortunately,thishasalsoprovedtobeoneofthemostdifficulttomeasureadequately.Severalmeth-Thispaperpresentsanewmethodforestimatingductodshavebeen

2、usedwithvaryingdegreesofsuccess.leakageinresidentialhomes.Thismethod,calledthenullingtest,doesnotrequireassumptionsoftheleakagecharacteris-Thispaperpresentsaproposednewleakagetestmethodticsofthehouseortheducts.Itmeasuresleakagetotheoutsidethathasshownimprovementsinbothaccuracyandperfor-anddoessoat

3、operatingconditions.Thisprovidestheleakagemancetimeinthefieldoverothermethods.Thismethodparameterthatisnecessaryforestimatingthermaldistribu-requiresnoequationsandisindependentofassumptionsabouttionsystemefficiency.Thispaperdescribesthenullingtestintheleakagedistributionofthebuilding.Italsomeasure

4、sthedetail,includingboththetheoryandhowtoperformthetest.leakageundernormaloperatingconditions.Fieldmeasure-Advantagesanddisadvantagesofthenullingtestarediscussedmentsfromthistestarealsopresentedandcomparedtootherandcomparedtothoseofotherteststhathavebeenusedinthemethods.past.Followingthesediscussi

5、ons,theresultsofseveralfieldtestsofthenullingtestsarepresentedandcomparedwiththoseCURRENTLEAKAGETESTMETHODSofothertests.BlowerDoorSubtractionINTRODUCTIONOneofthefirstleakagetestmethodsthatwasusedisThethermalefficiencyofforced-airdistributionsystemscalledtheblowerdoorsubtractiontest.Inthistest,ablo

6、werinresidentialbuildingshasbeenthefocusofsubstantialdoorisusedtodepressurizethehouse,firstwithalloftheresearchandmanyutilityprogramsoverthepastdecade.Thissupplyregistersandreturngrillesopen,thenagainwiththemworkhasshownthatductscanloseasignificantamountofsealedoff.Thedifferencebetweenthetwoisthee

7、stimateofconditioningenergyvialeakageandheattransferthroughducttheductleakage.walls.MathematicalmodelshavebeendevelopedthatThismethodhasseveraldrawbacks,however.Oneisthatcombineleakageandheattransferthroughductwa