外文翻译--现代螺杆压缩机设计实例.doc
英文原文1045ExamplesofModernScrewCompressorDesignsFig.5.20.Screwcompressorrotorsoptimizedforairconditioningandlightrefrigerationduty,leftandrotorsdesignedforheavyrefrigerationduty,rightthemotorcoolingprocessisevacuatedthroughthesuperfeedport.Apartfromtheinevitableresultingdecreaseintheplantcapacity,thecompressorefficiencywillbeunchanged.AcompressorwithsuchacoolingconceptisshowninFig.5.23.5.4.5MultirotorScrewCompressorsTheuseofmultiplemainorgaterotorsinonescrewcompressortoincreasecapacitywasproposedalmostattheintroductionofthesemachines.InFig.5.245.4DesignofRefrigerationCompressors105Fig.5.21.OriginalrotorsandcompressoroptimizedforgeneralrefrigerationandairconditioningdutyTable5.1.ExperimentalComparisonofCompressorPerformancewithRetrofitandStandardRotorsStandardRotorsEvaporation/CondensationTemp15/3035/35ShaftSpeedrpm29202920RefrigCapacitykW626216MotorPowerkW178156COP3.5231.383OptimizedRotorsEvaporation/CondensationTemp15/3035/350/35ShaftSpeedrpm292029202920RefrigCapacitykW6692431187MotorPowerkW182168245COP3.6711.4864.98COPImprovementNew/Old104.2%107.5%-amultirotorscrewcompressorwithtwogaterotorsisshown,asgiveninSakun,1960.Theideahasnotyetbeenfullycommercialised.However,severalpatents,suchasthoseofShaw,1999andZhong,2002havebeenrecentlypublishedinthatarea.ItisobviousthatthecapacityofmultirotorcompressorwillbeamultiplethecapacityofthecorrespondingordinaryscrewcompressorNonetheless,althoughitisfairlyselfevident,itisnotyetfullyappreciatedthattheefficiencyofamultirotormachinewillbenobetterthanthatofanumberofsinglerotorpaircompressors.Anotherfeatureofthemultirotorarrangementisthebalancingofradialforcesonthemainrotor.Unfortunatelytheaxialforcesonthemainrotor1065ExamplesofModernScrewCompressorDesignsFig.5.22.Compressorandretrofitrotorsoptimizedforgeneralrefrigerationdutycomparedwiththeoriginalrotors(lightline)5.4DesignofRefrigerationCompressors107Fig.5.23.Semihermeticcompressorwithmotorcoolingthroughsuperfeedportatthemotorhousing,farrightFig.5.24.Layoutofthemultirotorscrewcompressor1085ExamplesofModernScrewCompressorDesignsaresimultaneouslymultiplied.Generally,itiseasiertocopewithaxialthanwithradialrotorforcesbyusing,forexamplebalancingpistons.Hencethisfeaturecanberegardedasanadvantage.Thegaterotorforcesarevirtuallyunaffectedbythisarrangement.5.5MultifunctionalScrewMachinesOneofthepotentialadvantagesofscrewmachinesoverothertypesofpositivedisplacementmachineistheirabilitytoperformboththecompressionandexpansionfunctionssimultaneously,usingonlyonepairofrotors.Afurtherfeatureofthisistheuseoftherotorswhichsealonboth