The Simulation Research Of Combustion And Emission Performance For Heavy-duty LNG Engine Based On Turbocharged Inter-cooled And EGR

Because of the rich in resources, cheapness and cleanness, natural gas is consideredto be the most promising car engine alternative fuel, and liquefied natural gas(LNG) hashigher energy density and longer mileage, which make it the preferred fuel for gasengine applied in heavy trucks.In recent years,the natural gas cars are developingquickly in domestic and foreign, at the same time, the automobile emissions get moreand more attention by most of the countries in the world.The GB17691was publishedby China in2005, it provided the5th step emission limits including natural gas engine.The natural gas engine is mainly divided into two technical routes called lean-burn andstoichiometric combustion,both of them have their own advantages, the most productsmainly use the lean-burn technology, but the stoichiometric combustion is morepromising. Now the natural gas engine products that can meet China phase V usuallyused the foreign technology，lack independent development ability, so the productscannot be used widely.This paper’s aim is studying if there is stoichiometric combustion,what is the influence of combustion and emission performance that turbochargedinter-cooled and EGR technology gave to heavy-duty LNG engine the natural gasengine,and use the internal purification which links stoichiometric combustion,turbocharged inter-cooled and EGR technology to make it attack the emissionrequirements from China phase V.In this paper, AVL-BOOST software is used to build an engine model, includingturbocharged inter-cooled and EGR, which is based on a China phase V heavy-dutyLNG engine. After the calibration and the feasibility of the model was validated byexperimental data. Under the simulation condition which refered to ETC cycle in theChina phase V(1800r/min,25%,50%,75%,100%),the other parameters and conditions inthis model is unchanged,and a study on the influence of the engine combustion andemissions is made about inlet pressure, inlet temperature and EGR rate of single factor.Conclusions below can be getten, the inlet pressure, inlet temperature, EGR rate on theengine had a greater influence on the NOXemission and engine torque, but the CO andHC emission and fuel consumption rate was less affected. Among them, the EGR rateon the degree of influence NOXsignificantly greater than the other twofactors.According to the influence the rule and the level of engine performance by thethree kinds of factors, proposed the optimization scheme of combustion emission. By optimized EGR rate, intake pressure and intake air temperature successively, theheavy-duty LNG engine emissions this paper was meet the China phase Ⅴand otherperformance better.According the results in this article, a certain foundation on the further study of theinfluence of turbocharged inter-cooled and EGR technology for heavy-duty LNG engineperformance is laid. In this study, a theory basis is provided for independent developingnatural gas engine which meet China phase V standards for our country. At the sametime this study has a certain reference value.