TWC老化特性数值仿真及优化研究 VIP免费

TWC老化特性数值仿真及优化研究摘要目前，汽车已经成为人们生活中重要的交通工具。为了控制汽车的尾气排放污染，保护人类赖以生存的大气环境，世界各国纷纷采取严格的汽车排放标准，针对汽车污染研发了各种技术措施和控制对策，其中汽油机三效催化转化技术是目前应用最多的净化技术。本文对三效催化转化器的基本结构及其工作原理进行了简要介绍，并分三效催化转化器的老化机理，对三效催化剂的失活机理做了进一步的阐述。运用采用FLUENT软件，按照快速老化条件进行求解，通过数值模拟，得出三效催化转化器的温度场以及氧浓度场的分布情况，结果表明老化时间对老化具有较大影响，三效催化转化器特征转化效率随着老化时间的增加而降低，并且在老化初期下降急剧，随着老化时间的增加特征转化效率的下降变缓。三效催化转化器起燃温度相比老化前要高出60℃左右，起燃特性恶化，引起低速运转时排放量的大量增加。关键词：三效催化转化器；老化；反应机理；数值仿真AbstractAtpresent,thecarhasbecomeanimportanttraffictoolinpeople'slives.Inordertocontrolautomobileexhaustpollution,protecthumansurvivalenvironment,countriesaroundtheworldhavetakenstringentvehicleemissionstandards,developedfortheautomobilepollutionoftechnicalmeasuresandcontrolmeasures,thegasolineenginethree-waycatalyticconversiontechnologyiscurrentlythelargestapplicationofpurificationtechnology.Thebasicstructureofthethree-waycatalyticconverteranditsworkingprinciplewerebrieflyintroduced,theagingmechanismofandthree-waycatalyticconverter,ofthree-waycatalystdeactivationmechanismfurtherelaboration.UsingFLUENTsoftware,accordingtorapidagingconditionsissolved,throughnumericalsimulation,thethree-waycatalyticconvertertemperaturefieldandoxygenconcentrationfielddistributionisobtained,andtheresultsshowthatagingtimeonaginghasagreaterimpact,characteristicsofthree-waycatalyticconverterconversionefficiencyratedecreasedwiththeincreasingofagingtimeandduringtheearlyagingdecreasedsharply,withtheagingtimeincreasedfeatureconversionefficiencydecreasedslowly.Thethree-waycatalyticconverterignitiontemperaturecomparedbeforeagingtoabout60DEGC,ignitionperformancedeterioration,causedbylowspeedwhenemissionsofasubstantialincreasein.Keywords：Thethreewaycatalyticconverter;aging;reactionmechanism;numericalsimulation目录摘要................................................................................................................................IAbstract..........................................................................................................................II1前言.............................................................................................................................12TWC老化机理研究...................................................................................................22.1TWC的结构及工作原理................................................................................22.1.1三效催化转化器的结构.......................................................................22.1.2三效催化转化器工作原理...................................................................32.2TWC的老化机理............................................................................................42.2.1高温热失活...........................................................................................42.2.2化学中毒...............................................................................................62.2.3结焦...........................................................................................