果蔬冷藏工藝與品質(zhì)衰變理論與實驗研究.pdf

1、天津大學(xué)博士學(xué)位論文果蔬冷藏工藝與品質(zhì)衰變理論與實驗研究姓名：譚晶瑩申請學(xué)位級別：博士專業(yè)：制冷及低溫工程指導(dǎo)教師：楊昭20070620ABSTRACTColdchainsistheverysystematicengineeringoffreshnessoffruitsandvegetables，whichisdirectlyrelatedwiththelossofoffiuitsandvegetablesaftertheirposth

2、arvestPre—coolingandcoldstorageofthecoldchainswerediscussedPhenomenonofheatandmasstransferdisintegrationofqualityandtechnicsofcoldstorywerestudiedindetailThemaincontentsandconclusionsofthispaperareasfollows：lTestingandan

3、alysisonthecoldstoragewithconstanttemperatureandconstanthumidityFull—frequencydropintemperatureandconversiondropintemperaturewerecomparedThelatterhassomemeritsofsmoothdropandsmallamplitudeoftemperatureindespiteofshortage

4、oflongertimeSeveralmodesofprovidingwindwerestudiedFlowequalizationwithporeplateisbetterthanthetraditionalmodessuchasonefantwofanandjacketHeatimpactonthecircumstanceinthecoldstoragewasanalyzedbecauseofthedooropenandsomepr

5、ecautionarymeasureswereadvanced2ExperimentalstudyontheforcedairprecoolingoffruitsandvegetablesExperimentsOiltheforcedairprecoolingofapplesandcucumberswerecarriedouttoanalyzeinfluenceoftemperatureofcoldairhumidityofitvelo

6、cityofitandvoidratioofapplesandcucumbersOilpre—coolingprocessVelocityof15m／sisthebestoperationvelocityGoodresultsaleobtainedwithlowtemperature(nochillinginjury)andhi曲humidityair(S0％RHabove)voidratioofapplesandcucumbersha

7、slittleinfluenceontheprecoolingtimewhentheairvelocityishigherthan1Sm／s，whileithasgreatinfluenceontheprecoolingtimewhentheairvelocityislowerthan075m／sSomorefruitsandvegetablesaleadvisedtobeprecooledathJ曲airvelocitywhilewh

8、ichreducetheefficiencyofprecoolingatlowairvelocity3TheoreticalstudyonthecouplingofheattransferandmasstransferNondimensionalmathematicalmodelwasestablishedoftorisphericalfruitsandvegetablesandqusi—cylindricalfruitsandvege

9、tablesInfluencesofsomekeyparameters(forexample，Re)onthepre—coolingprocesswereinvestigatedtheoreticallyThetheoreticalanalysiswasvalidatedbyexperimentalresults7931ofReand27870fRealethebestoperationonesrespectivelyfortorisp