食品冷藏陈列柜的传热机理及强化传热试验研究

郑州轻工业学院硕士学位论文食品冷藏陈列柜的传热机理及强化传热试验研究姓名：石海军申请学位级别：硕士专业：制冷及低温工程指导教师：吕彦力2007-06I1.2.133.4.12345.IIABSTRACTAttractivefoodproductsareoftendisplayinchilledcabinetsinsupermarkets,whichisthelastlinkinthecoldchain.Thequalityofdisplayedfoodsisveryimportanttothehealthofconsumers,butthefoodtemperaturesarehighandtemperaturedistributionofcabinetsisuneven,whichaffectthefoodqualityseriously.Inaddition,becauseenergyconsumptionofcabinetsisveryhigh,manysupermarketsruntherefrigerationunitabnormallyinordertosaveoperationcost.Sothekeyproblemsofcabinetsdesignaretoreducefoodtemperatureandimprovethedistributionwithoutincreasingtheruncharge.Accordingtotheabovequestion,theoryanalyzesandexperimentalmethodsareusedtoinvestigatetheseproblemsinthispaper,conclusionsareasfollowed:1.Factorsthataffectdisplayedfoodtemperatureareinvestigatedbasedontheoryanalyzes,theresultshowsthatthepoortemperaturedistributioniscausedmainlybythecabinetstructureandfooddisplaystyle,andthesefactorsaretemperatureandvelocityofchilledair,temperatureofclapboard,radiationofbackpanelandindoorlight,temperatureandhumidityofsupermarket,andsoon.2.Temperaturedistributionofeveryfloorisstudiedwithexperimentalmethod,theresultshowsthattemperatureofforesideairisthelowestandofrearwardairisthehighestin1stfloor,buttheresultisoppositeinothersfloor,otherwise,temperatureoffrontalclapboardandfoodisthehighestandofthebackisthelowest.3.Withthehoistofindoortemperature,humidityandlightradiationrespectively,thedisplayedfoodstemperatureisbecomehigher.Moreover,1ightradiationinfluencesthetemperaturealotwhentheintensityisreachedsomevalue.Solowerindoortemperature,humidityandlightradiationisgoodforfoodquality.4.Ladderstyleoffoodplacementcanreducefoodtemperatureinthe1stand2ndfloorwithoutincreasingenergyconsumption,butincreasethetemperatureinthe3rdand4thfloor,thereasonisthatfoodsinupperflooraremainlychilledbyinneraircurtain,butinthenetheraremainlycooledbybackpanelflow.5.Heatpipesweredesignedandproduced,whichwereusedtoenhancedheattransferbyputtinginthebottomofclapboardinthe1stfloor.TheexperimentalresultsshowthatfoodIIItemperatureandthetemperaturedifferenceoffrontalandbackfoodarelowedalotandalsowithoutincreasingenergyconsumption.Keywords:cabinets,foodtemperature,temperaturedifference,energyconsumption11.1192241.2805085[1]1.3FluentTiCl421.3.1()[2-3]k-FLUENTPHOENICS[4-9][10-11][12]TiCl4[13][14-17]1.3.2[18-20][21]3()50[18]SANYOCOPELANDSANYOCOPELANDBitter[22][23][22][24][25]R22R134aR407cR134aR22R134a[26]R407c[23][27]40%30%[18][28]17%20%41.3.305[29-31]Olsson[32]5K24KFaremarziWoodworth[33]2K1.3.4[34-35][36][37-38][39][40-42]1.41.Fluent2.BSEN-441NI53.4.5.6.62.12-12-1Fig.2-1Atypicalmulti-decktypedisplaycabinets2.272.3Fluent2.4[43]2.4.12.4.1.18Boussinesq2.4.1.21()()0uvxyρρ∂∂+=∂∂2-12()()22222''''uuuvuuvpuuxyxxyxyρρµρ∂∂∂∂∂∂∂+=−++−+∂∂∂∂∂∂∂2-2a()()22222''''uvvvvuvpvvgxyyxyxyρρµρρ∂∂∂∂∂∂∂+=−++−+−∂∂∂∂∂∂∂2-2bµρg'','',''uuuvvvρρρBoussineq[47]'',()jiijtijtjiuuuupxxρδµ∂∂−=−++∂∂(2-2c)3()()2222''puTvTTTuTvTxycxyxyρρλρ∂∂′′∂∂∂∂+=+−+∂∂∂∂∂∂2-3''jtjTuTxρ∂−=Γ∂2-3atttµσ=Γ2-3bσt1.394k()()2222tpkukvkuvPxyxyρρµµρεσ∂∂∂∂+=+++−∂∂∂∂2-4PpjjiptijiuuuPxxxµ∂∂∂=+∂∂∂2-4a5ε()()()221222tpuvcPcxyxykερερεµεεεµρεσ∂∂∂∂+=+++−∂∂∂∂2-52.4.1.30m/s0.12.4.22-2aaaTemperaturedistribution10b(b)Velocityvector2-2Fig.2-2TemperatureandVelocityDistributionChart2-2b2-2a2-2b2.5113.13.1.1[44]BSEN441-43251603250.911600100lux2/m60.10.2m/s3-1Fig.3-1Directionofairflowbeforefooddisplaycabinets3.1.2420036003600(mm)7cm1%3.1.311211015/h0.51530/h13/h30/h23AIRFLOWAFX-102A6.6kW132040m3/h7.5kw12.3kg/h1.7kW3-2Fig3-2Pictureofthelab3.2133.2.1T0.2mm3-30HJ3A3-3NI3-3Fig.3-3Thepictureofthermocoupledemarcation3.2.2[45](NationalInstrumentNI)(VirtualInstrument)NILabVIEWlaboratoryvirtualinstrumentengineeringworkbenchPXI-1042SCXISCB-68PXI-1042PXI-8186PXI-6251SCXISCXI-1000SCXI-1102SCXI-112514SCXI-11803.2.31PXI-1042PXI-8186PXI-6251SCXI-1349SCXI1000SCXI-1102SCXI-1303SCXI-1180SCXI-1303SCXI-1102SCXI-1349PXI-6251PXI-8186Measurement&AutomationLabVIEW3-43-53-4PXISCXIFig.3-4Principlepictureofmulti-temperaturesuperviseandmeasurementsystem3.5Fig.3.5Pictureofsuperviseandmeasurementsystem2Measurement&Automation15LabviewDAQ113-63-6Fig.3-6Thetemperaturemeasurementprogram3.3BSEN441-4164.14.1.1BSEN441-450100200mm1000g4.1.23636144NI4-1Fig.4-1Schematicofthefoodsamplesandthermocouples174.24.2.114-2196.55.53.54-3155.3614-48.886.52.34567891014710131619222528m4-21Fig.4-2Temperaturesoftheshelfin1floor34567814710131619222528m4-31Fig.4-3Temperaturesofchilledairin1floor184-24-31444567891014710131619222528m4-41Fig.4-4Temperaturesoffoodsamplesin1floor4-24-41.54-24-41194.2.224-510.414-62.59.514-7118.57.83.277.588.599.51010.514710131619222528m4-52Fig.4-5Temperaturesoftheshelfin2floor77.588.599.51010.51111.51591317212529m4-62Fig.4-6Temperaturesofchilledairin2floor2077.588.599.51010.51111.51591317212529(m)4-72Fig.4-7Temperaturesoffoodsamplesin2floor4-54-64-54-74.2.334-811.310.39.81.54-9131010.734-83Fig.4-8Temperaturesoftheshelfin3floor219101112131414