Studyonturbocompoundsystemforaheavy-dutydieselenginebycombiningmatchinganalysiswithexperiments.docx

ProclMechEPartD:DOI: 10.1177/09544070221104350S SageReviewArticIeStudyonturbocompoundsystemforaheavy-dutydieselenginebycombiningmatchinganalysiswithexperimentsYinYong1,2®,WuZhijun1zZhaoRongchao3GzZhugeWeilin4andHuZongjie1AbstractJAutomobiteEngineering2023,Vol.237(8)1775-1789IMechE2022Articlereuseguidelines:Inthiswork,toimprovethefueleconomyoflong-haulcommercialvehicles,theeffectsofturbocompoundsystemmatchingonengineperformancewerenumericallyandexperimentallystudied.Firstly,aIDGT-POWERsimulationmodelofan11Lheavy-dutydieselenginewasestablishedandverifiedbytheexperimentaldata.Secondly,theperformancesoftheturbocompoundenginematchingwithdifferentsizesoffixedgeometryturbine(FGT)andpowerturbineswereanalyzed.Itwasfoundthattheexhaustenergydistributionbetweentheturbochargerturbineandpowerturbinehadasignificantimpactonengineperformance,andthesizeoftheturbochargerturbinehadamorenoticeableimpactthanthepowerturbine.BasedontheFGTturbocompoundsystemsimulationresult,anappropriatevariablegeometryturbocharger(VGT)andthreewastegateturbochargers(WGT)wereselectedforfurthersimulationandexperimentalresearch.Inaddition,theimpactsofthetransmissionratiobetweenthepowerturbineshaftandtheenginecrankshaft,andthefuelinjectiontimingontheengineperformancewereexperimentallystudied.Theenginetestresultshowedthatthefueleconomywasimprovedby1.6%underEuropeanSteadyState(ESC)cyclewhilekeepingtheweightedNOxemissionthesameastheoriginalengine.Finally,theturbocompoundenginewithWGTwasinstalledonaheavy-dutylong-haulcommercialvehicleforroadtests.Thefueleconomyofthevehiclewasimprovedby2.54%underthe80km/hconstantspeedroadtest.KeywordsTurbocompoundsystem,heavy-dutydieselengine,variablegeometryturbine,wastegateturbine,powerturbineDatereceived:27October2021;accepted:2May2022IntroductionDieselengineshavebeentheprimarypowersourcesforcommercialvehiclesandengineeringmachineryforalongtimebecauseoftheirexcellentadaptability,highefficiency,andreliability.Itisimportanttofurtherimprovethedieselengine'sthermalefficiency.Thein-cylindercombustionprocessofdieselengineshasbeendramaticallyimprovedbytechnologiessuchashigh-pressurecommon-rail,high-efficiencyturbocharging,andexhaustgasrecirculation(EGR).Dieselengines'brakethermalefficiency(BTE)hasreachedmorethan45%.However,ithasbecomeincreasinglydifficulttoimproveBTEonlybyoptimizingtheincylindercombustionprocess.Wasteheatrecoveryisgenerallyacceptedtoimprovetheengine'soverallefficiency.Themaintechnologiesofwasteheatrecoverj,includeOrganicRankineCycle(ORC),1ThermoelectricGeneration(TEG),2andturbocompounding.3ComparedwithORCandTEGtechnology,turbocompoundinghastheadvantagesofrelativelysimplestructureandgoodenergy-savingperformance.Inaddition,theenginebackpressurecanbeincreasedsignificantlyduetoapowerturbinedownstreamoftheturbochargerturbine.Asaresult,ahigherEGRratecanbeadoptedtoreduceNitrogenOxides(NOx)emission.Furthermore,theengineexhaustenergyisabundantforlong-haulcommercialvehiclesbecausetheir1TongjiUniversity,Shanghai,China2DongfengCommercialVehicleCo.Ltd.,Wuhan,China3SouthChinaUniversityofTechnology,Guangzhou,China4TsinghuaUniversity,Beijing,ChinaCorrespondingauthor:ZhaoRongchao,SouthChinaUniversityofTechnology,381WushanRoad,TianheDistrict,Guangzhou510640,China.Email:merczhaoenginesmainlyoperateathighspeedsandhighloadscomparedwithpassengercarengines.Therefore,itisconducivetoreducingfuelconsumptionbyapplyingturbocompoundtechnologyinlong-haulcommercialvehicles.Inaturbocompoundengine,apowerturbineisusedtorecovertheexhaustenergyandturnitintomechanicalworkorelectricity.Therearethreemainconfigurationsforthepowerturbineandturbocharger,includingseries,parallelandintegratedlayouts.Weietal.4comparedtheperformanceofa1.8LturbochargedgasolineenginewiththreeIurbocompoundlayoutsunderdrivingcycles.Itwasshownthattheparallelturbocompoundlayouthadthebestfuelsavingperformance.However,theexhaustmassflowratiobetweenthepowerturbineandturbochargerturbineneedstobeadjustedusingtwovalvesaccordingtotheengineoperatingcondition.Sincetheoperationconditionfrequentlychangesontheroad,theparallelconfigurationisunsuitableforvehicleapplication.Inintegratedlayouts,5amotor/generatorisintegratedwiththeturbocharger.Itactsa$amotortoacceleratetheturbochargeratlowenginespeedconditionsforbettertransientresponseandasageneratortorecoverthewasteheatforlowerfuelconsumptionathigh-speedconditions.Thematchingandcontrolmethodfortheintegratedturbocompoundsystemiscrucialtogethighoverallefficiency.Yangetal.6proposedamatchingguidelinefortheintegratedturbocompoundsystemandappliedittoatwo-strokelowspeedmarineengine.Resultsshowedthatthefuelconsumptioncouldbereducedby2%-3%althreeloadprofiles.Joshietal.78proposedanovelsystemconsistingofsupercharging,turbocompounding,andelectrification.Thepowerflowcouldbeoptimallymanagedinthislayoutbyemployingaplanetarygearsetaccordingtotheroadconditions.Resultsshowedthatthefueleconomywasimprovedby11.1%.Themainchallengeforan