In order to investigate the fuel economy,environmental impact and power performance of hydrogen direct injection engine under lean combustion,a study on the combustion characteristics of hydrogen direct injection engines under different mixture concentration and different load was conducted.The results revealed that lean combustion could reduce the combustion rate and the rate of cylinder pressure rise,while improving thermal efficiency by reducing heat transfer losses through an increased working fluid specific heat ratio.The influence of mixture dilution on flame propagation was significant,whereas the impact of load on combustion duration was relatively minor.The highest NOX emissions were observed within the excess air ratio λ range of 1.1-1.6,but both mixture enrichment and dilution were effective in reducing emissions.Increasing the load also resulted in a significant increase in NOX emissions.At low loads(the mean effective brake pressure(BMEP)is 0.2 MPa),NOX emissions remained below 10-5 when λ exceeded 1.8.However,at higher loads(BMEP=1.2 MPa),even at λ=2.0,NOX emissions still exceeded 0.002.
关键词
氢气直喷发动机/稀薄燃烧/燃烧特性/混合气稀释/NOX排放
Key words
hydrogen direct injection engine/lean combustion/combustion characteristics/mixture dilution/NOX emissions
维普
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