Simulated And Experimental Investigations Of Combustion Processes In Natural Gas Fueled Compression Ignition Engine

In this paper, a new combustion system of natural gas fueled compression ignition engine is presented. In order to let high octane number natural gas to be compression ignited, measures like high compression ratio, glow plug heating, heat-isolating coating, as well as air inlet heating, are adopted in this system. In order to overcome misfiring and cylinder knocking caused by high octane number natural gas in the process of compression ignition and combustion, divided chamber and compound natural gas supply system are applied in this system, therefore the stratified concentrations and temperature distribution are realized while ignition timing and combustion rate are controlled effectively and operation range is broadened. In order to improve engine start-up performance, broaden the lean limit and increase operation range in high load condition, additive and hot Emission gas Recycling (EGR) are used in this system and an obvious effect is achieved.The developing work for natural gas fueled compression ignition engine is introduced in this paper, including concept design of new combustion system, structural design of combustion chamber and heat isolation, layout design of compound natural gas supply system, EGR system and combustion assistant additives supply system.The study of simulation and analysis of combustion mechanism referring the combustion system is introduced in this paper.In order to simulate the combustion process and investigate its combustion mechanism and affecting factors, a reduced kinetic dynamic mechanism of natural gas is established based on 23 species and 42 reactions. The mechanism is used to simulate combustion process through coupling with Computational fluid dynamics (CFD) software.The simulating results show that reasonable stratification of mixture concentration and temperature distribution can be formed in compound gas supply mode through controlling inlet air temperature, in-cylinder mixture concentration during the end of inlet stroke, glow plug temperature, gas supply volume and injection timing,so a two-stage combustion is realized and its operating range is broadened. Based on analysis, it is learned that inlet air temperature, glow plug temperature and natural gas supply volume have much influence on ignition and combustion process of natural gas fueled compression ignition engine. Their functions are activated...