Numerical Simulation And Study On The Combustion Process Of DME Engine

Dimethyl ether (DME) is one kind of newly and clean substitute for diesel engine, which is obviously different from diesel on property. The research that DME is universal used on diesel engine is processing and the mechanism of combustion, process and characteristics need a lot of basic research.The contents of research derived from the development of DME engine as a part of preliminary studies. One 490 turbocharged diesel engine has been taken as the object of study in this article. First of all, the numerical simulation of using DME and diesel oil fuel respectively in diesel engine by means of the software STAR-CD, and comparison of them. Secondly, the performance of DME engine is calculated with different load. Finally, Calculation and analysis of the performance for DME engine with different nozzle under different advanced injector crank angle. The results are as follows:(1) Whether fueled with diesel or DME, the distribution of cylinder fuel becomes larger with the increase of advanced injector crank angle, and corresponding to improving the quality of in-cylinder inflammable mixture. The maximum temperature, pressure and NOX emission increase with the advanced injector crank angle increases. Under the same advanced injector crank angle, the results indicate that DME used in diesel engine demonstrates the maximum temperature, pressure and NOX emission are lower than diesel oil.(2) When the diesel engine fueled with DME, the maximum in-cylinder temperature, pressure and NOX emission increase with the increase of the load (fuel injection quantity). In the same advanced injector crack angle (11oCA and 13oCA), the maximum in-cylinder combustion pressure decreases, then goes up, and finally declines with the nozzle diameter increases. But NOX emissions in cylinder reduce with the nozzle diameter increases.(3) From the view of fuel economy and emission, the best advanced injector crank angle is 11oCA, which not only can control the emission of NOX effectively, but also reduce fuel consumption rate appropriately. The optimal nozzle diameter is 0.32mm, which not only can maintain a higher in-cylinder pressure, but also it can reduce the emission of NOX. The research results can be further used to spread DME and give a reference about changing the diesel engine to DME engine.