Development of a hydrogen free-piston engine generator for range extenders

Free -piston engine generator (FPEG), as an important branch of range extender, is a very competitive development direction. In this paper, a hydrogen -fueled opposed -piston FPEG is proposed, which adopts a mechanicalpressurized structure and a two -layer control strategy based on the inner and outer dead center. The prototype well meets the requirements of stable power generation and vehicle loading. The experimental tests have been conducted, which show that the pure hydrogen is successfully ignited under the cold start condition, the combustion efficiency and generation efficiency reach 30 % and 20 % respectively, and the peak pressure is close to 40 bar. However, the prototype was unable to enter the stable operation stage due to frequent misfire phenomena. Based on the above, the causes of abnormal combustion were discussed and the energy loss of the prototype was calculated. The prototype was simulated to run in the stable operation stage finally, and the future optimization scheme based on control strategy and structure was concluded.