Combustion Characteristics of a Methane-Hydrogen Dual-Fuel Engine Ignited by Diesel Pilot Injection
Combustion process characteristics were studied on a methane-hydrogen dual-fuel engine ignited by die-sel pilot injection at different initial intake temperature,hydrogen energy ratio and injection time.The methane-hydrogen-air mixture is injected near top dead center(TDC)and ignited by pilot injection of 5％(energy ratio)die-sel fuel.The effects of hydrogen energy ratio on ignition delay time,combustion duration and heat release rate in each stage of the dual-fuel engine were investigated under the intake temperature of 25 ℃ and 50 ℃,respectively.The natural photometric images of the combustion process were recorded by a high-speed camera,and the crank-shaft rotation angle corresponding to each natural photometric images was calculated.The combustion stages were identified by analyzing heat release rate(HRR)curves and second derivative of heat release rate(SDHRR)curves.The results show that the ignition delay period first decreases with the increase of hydrogen energy ratio when the intake temperature is 25 ℃,and then increases after the hydrogen energy ratio reaches 60％.The combustion dura-tion decreases by 41％with the increase of hydrogen energy ratio.When the intake temperature is 50 ℃,the igni-tion delay period further decreases and the combustion duration significantly decreases.As the temperature increases,the proportion of the first and second stages of combustion heat release gradually increases,while the proportion of the third stage gradually decreases,leading to an earlier combustion heat release process.
dual-fuel combustionsecond derivative of heat release ratenatural photometric images
万方数据
维普
