The Experiment Study Of VNT Turbocharger On Performance And Emission Of A Common Rail Diesel Engine

Energy lacking and environment pollution are two problems that all countries in the world are confronted with today. Variable Nozzle Turbocharger can cooperation with diesel engine in large operation area, improve the transient performance and economy of diesel engine, and is one of the key technology of modern diesel engine. EGR technology based on VNT is one of the main technical measures to fulfill the EUROâ…£emission standard.This research is carried out on a common rail diesel engine. The study intends to investigate the inpact of VNT and EGR on diesel engine performance and emission. First, do the VNT experiment; investigate the impact of VNT on engine's economy, performance and emission. And get the control MAP of VNT on this engine. In some conditions, the boost pressure is higher than exhaust pressure, EGR can not realize. We design a high pressure cooled EGR system which is controlled by VNT and one-way valve. The change of VNT vane position will not only affect the boost pressure and intake mass flow, but also affect EGR mass and EGR ratio. Investigate the influence of the vane position on engine performance, economy and emission. Adjust the injection parameters, find their impact on diesel engine performance. According to the improved NOx-PM and NOx-fuel consumption trade-offs, and aimed at NOx emission lower than EUROâ…£and PM emission lower than EUROâ…¢, choose the optimized vane positions and injection parameters.Research results show that, use VNT turbocharger, the transient performance, the fuel consumption of large load and high speed condition are improved, and the emission declines to a certain extent. The optimized cooperation of VNT, EGR system and injection parameters have greatly improved the engine's emission, the NOx and PM emissions are declined markably, the NOx emission almost pass the EUROâ…£standard, while the PM emission does not change, and the fuel consumption is 4.2% lower than EUROâ…¢level. Desirable engine performance and emission are obtained.The research result can provide practical value and guides for the application of VNT and EGR on heavy duty diesel engine to fulfill the EUROâ…£standard.