缸内直喷氢燃料内燃机技术发展及趋势

Hydrogen energy is the best energy carrier to achieve carbon peak and carbon neutrality, and is also regarded as the ultimate energy source in the 21st century. The hydrogen internal combustion engine has the significant advantages of zero carbon emission, high efficiency, high reliability and low cost, which makes it one of the important directions for hydrogen energy applications. The direct-injection hydrogen internal combustion engine, which can effectively suppress backfire and significantly increase power density, is a hot topic in the recent stage of development of hydrogen engine. It has attracted much attention from traditional automobile companies and research institutes at home and abroad. This paper systematically summarizes the advantages and disadvantages of various types of hydrogen internal combustion engines as well as the technical approaches and the details of the relevant hydrogen engines. The utilize of exhaust gas turbocharging can make the power density of hydrogen internal combustion engine reach 80 kW/L. High compression ratio and lean burn combustion can reach the brake thermal efficiency to 42% ~ 45%, and the exhaust gas recirculation technology can reduce the NO_x pollutant of hydrogen engine less than 0.5 g/kWh. The paper also addresses the new issues posed by the next-generation direct-injection hydrogen engine, analyzing the current state of development and the technical details including mixture formation, combustion characteristics, combustion mode, effective thermal efficiency improvement, NO_x control methods and post-processors. We also discuss the future technological development trend of reaching 50% brake thermal efficiency under near-zero emission working conditions.