Research On CNG Engine Emission Performance

Since the birth of the first human combustion engine vehicle the human economic development increasingly rely on fossil energy sources. By facing increasingly serious energy shortage and enviroN?mental pollution, all nation strategy for energy security have adopted the strategies of diversification of energy sources. At this time, the development of new energy and enviroN?mental protection and energy saving engine has become an important strategy of sustainable development to achieve for all the automotive industry. After a hundred years of development, the diesel and gasoline engines as the backbone of an automobile engine, has become a mature power machinery with high degree. As the new energy sources power machinery such as battery and fuel cell also encounter technical issues and commercialization problem. Natural gas are becoming the focus of attention due to the absorption of diesel and gasoline mature technology advantages and the characteristics of the world’s natural gas reserves. In this paper, combining the subject of expansion “Technology Development of emission Ⅳ to emission Ⅴ in T10 natural gas engine”, cooperate by SINOTRUK JINAN FUQIANG POWE CO., LTD. and Xihua University.with the T10 NG engine as based models,matching the NG control systems and catalytic, calibration,emission optimized at last.Base on the analysis of NG engine technology, matching two NG control systems and test the hybrid combustion program. The final technology solution to meet the emissison Ⅴ has been proposed: lean-burn, turbocharging and intercooling system, single-cylinder with independent high-energy ignition, EPR and CFV NG control system with closed loop control by UEGO and oxidation catalytic. Which made the NG engine meet the requirements.After studying the emissions regulations, the program based on the steady state emission, focusing on the transient emission has been designed. With the calibration of the NG engine control system and matching the turbocharger and catalytic, the group studied impact of excess air ratio and ignition timing on CNG engine emissions. To meet the emission requriment, an operating point with better dynamic and economy has been found. It summarizes the main factors of emission in the process of calibration.Through difference excess air ratio and ignition timing adjustment and the test of misfire and knock in the engine. A NOx trend that in the large operating area is discovered. That is the decrease of NOx with larger ignition timing and smaller excess air ratio. But it’s not the absolutely in the whole work area. This is important for transient emission.Finally, the NG engine pass the ETC test. The performance of NG control system and catalytic has been summarized. It helpful for the next development of NG engine.