Research On LNG Engine Combustion And Its Optimization

As the alternative fuel of traditional internal combustion engine, natural gas can fully burn, Gas emission and the cost are low. Therefore, in recent ten years, LNG engine bus,truck, and other fields in our country has gotten a good and rapid development. Based on the natural gas engine technology research and development in Shanghai diesel engine co.,LTD, Mainly studied LNG(liquefied natural gas) engine combustion modes, Analyze the advantages and disadvantages of different LNG engine combustion mode, Put forward a kind of new combustion mode better than lean combustion mode, can satisfy the lower emission standards at the same time has good power performance. The new combustion mode is mix combustion technology combines equivalent + lean combustion model. Then Carry out experimental study on the engine test bench and vehicle performance.The research of this paper is based on SC8DT250Q5 LNG engine bench test. First make lean combustion analysis model and equivalent combustion mode test bench, Then make LNG engine mix combustion mode technology scheme design and control strategy.Then make mix combustion of LNG engine test bench experiments, and verifies the performance of the LNG engine. At the same time, analysis the combustion optimization in the experiment and find a new way to develop a new LNG engine which is environmental,energy saving and dynamic. Specific as follows:(1)Do the single lean combustion model and single equivalent combustion model experimental research(The influence of ignition advance Angle on the combustion; The influence of excess air coefficient of combustion; Post-processing emission performance etc).(2)Research on mix combustion scheme design: How to implement the mix combustion technology, namely how to combine lean combustion mode and equivalent combustion mode, and put forward the mix combustion mode control strategy.(3)Research on mix combustion LNG engine bench test, especially mixed combustionmodel optimization. Realized two combustion model smooth switch, and completed the ETC circulation transient emission test, reached the standard of Euro V.(4) Do the vehicle test calibration: Optimize the vehicle dynamic performance and fuel economy through the comprehensive calibration and verification of the vehicle driving.Mainly make LNG engine combustion analysis and optimization research from the aspect of combustion models and put forward the mix combustion technology combines equivalent + lean combustion model in the thiese. After the combustion experiments and the vehicle test, show that this technology achieves the goal of optimizing combustion without doing a lot of changes in the original engine. In LNG engine combustion process,according to the different load, smoothly switch to the corresponding equivalent and lean burn area. At the same time, adjust the ignition advance Angle, the throttle opening and so on. Make sure that save fuel and reduce emissions, reduce the heat load, increase thermal efficiency, maintain or improve the comfort of the engine, and meet euro V emission standard technological breakthroughs on the basis of guarantee the original engine dynamic performance and LNG Smooth engine operation and comfort of the vehicle driving.