Performance Analysis By Numerical Modeling And Experimental Study On A Diesel Engine With Miller Cycle

Generalized miller cycle include atkinson cycle and miller cycle in the traditionalsense. It is controlled by the valve closed time. The actual compression ratio and theexpansion ratio can be changed in this way, so that the combustion pressure andtemperature will decreased, the NOx emissions will be reduced, the pump gas loss will bereduced, and the economy will improve,it get to achieve the aim of improve the thermalefficiency and reduce emissions. Due to the design of miller cycle of engine without bigchanges, just by adjusting the valve timing.It is easy to come true, it also promoted themiller cycle engine into practical application.It is based on an electronically controlled high pressure common rail fuel injectionengine in this paper. Using CFD software to calculate miller cycle, then test on the engine.Using the working process software in different inlet closed Angles,the calculation resultsshow that under full load and partial load,the power, torque, BMEP is very significant toIVC in miller cycle.But this influence in atkinson cycle is not very significant; Fuelconsumption in the atkinson cycle with inlet closed Angle of delay a rising trend, but it isnot obviously, fuel consumption of miller cycle increases obviously, with the valve closedAngle in advance.Then study about the influence of advance injection Angle、multiple injections、Injection pressure、the EGR rate influence、The inlet pressure effects on miller cycleengine.The calculation results show that when the injection advance Angle is bigger, thepressure is higher, the NO emission increase, and the temperature is higher; Pre-injectionadvance Angle can reduce NO emissions and the pressure rise rate significantly. When theinjection pressure is higher,the pressure in cylinder is higher, the NO emission increase,the SOOT emission increase, the temperature in cylinder is higher; Compressorcompression ratio have obviously effect on combustion pressure; When the EGR rate ishigher, the NOx emission is lower, but cylinder pressure decrease.At the last,we will get acomprehensive summary about miller cycle influence on all aspects of the important indexof diesel engine performance.