降低汽油机有害排放物NOx的分层废气再循环的研究

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1、天津大学博士学位论文降低汽油机有害排放物NOx的分层废气再循环的研究姓名：刘增勇申请学位级别：博士专业：动力机械及工程指导教师：姚春德20031201ABSTRCTItisagreatchallengefortheautomotiveindustrydevelopmenttomeettherequirementformoreandmorestringentenvironmentpollutionregulationsandsevereshortageofpetroleum0il．AsNOxemissionfromSIengineisoneofmaincomponentst

2、ofoITnoptical-chemicalsmoke，itisveryimportanttorestrictNOxemissions．Intheexistingmethods，EGRisrelativelyeffectivetechnologynotonlytoreducetheemissionofNOxbutalsotosaverueIconsumptionatpartIoad．TheconventionalEGRdirectlyenteringintakemanifoldislimitedbycycle’bv，cyclevariationandfurtherdecr

3、easingNOxemission，iflargeratioofEGRleadstoengine，whichwillincrcasefuelconsumptionandC0andHCemissions．However，thestratifiedEGRwithdecreasingofthecycle-bv—cyclevariationandincreasingoftheratioofEGR，notonlyreducestheemissionofNOxfurtherandthepumpinglOSSatpart10adbutalsoimprovesthefueleconomv

4、．SothestratifiedEGRistakenasaimportantmeanstoreducetheemissionofNOx．ThestudyfocusesonthetechniqueofstratifiedEGR，whichconsistsofthemechanismofstratification，theforillofstratificationandtheinfluenceonmixtureforill，combustionprocessandengineperformanceundertheconditionofstratification．There

5、searchselectsafour．cylinderSIenginewithfourvalvesforeachcylinder，whichproducesstrongtumblemotionanddevisesspecialstratifiedconfigurationofEGR．neexhaustgasisleadedtosingleintakeportbytheguidedjetandachievesstratificationwithfreshmixturebyusingtumblemotionoftheengineinthecylinder．Thediffere

6、ntEGRmodesarerealizedbychangingthelocationoftheguidediet．TheresultofthetestdemonstratesthatthemodesofEGRhaveobviousinfluenceonengineperformance，Atpartload，thejelbythesideofintakeportattainsbettereconomythanconventionalmodewiththefuelconsumptionreductionbv4．1％．Simultaneously,NOxandCOaswelI

7、asHCreducesmostlywiththeincreasingofEGRratio．ThewholeEGRratioswiththemodethatthejetlocatesbythesideofportarelargerthanthatoftheconventionalmodeandthemaximumratioreachesto43％．AttheconditionofsameEGRratio，cylinderpressureoftheside@tmodeisbiggerthanthatofconventionalmo