As the individual and commercial vehicle industries seek sustainable alternatives to conventional internal combustion engines (ICEs), hydrogen-fueled rotary engines are emerging as a promising solution for several applications. This paper presents an innovative approach for the development of a hydrogen rotary engine that is integrated within a hybrid system. By exploiting the unique characteristics of rotary engines, such as compact size and high power-to-weight ratio, the electric machine, the battery and the rotary engine can be accommodated in the installation space of a conventional ICE with comparable power, despite the reduced power density of hydrogen as a fuel in ICEs.
As a first step, the hydrogen engine is naturally aspirated and equipped with direct injection. To develop a suitable calibration for the engine’s application, the influence of calibration parameters such as ignition and injection are investigated. The study examines the influence of these on operating behavior, fuel efficiency and emissions. This is supported by comprehensive measurement systems including cylinder pressure indication and emission analysis, which allows deep insights into the combustion process. First results show, that the ignition timing has only a minor influence on efficiency, but the formation of nitrogen oxides (NOx) varies by a factor of more than five as a result of an adjustment. Instead, the efficiency is primarily dependent on the mixture formation, which is significantly influenced by the injection pressure and timing.
This research highlights the potential of hydrogen rotary engines as a viable route to near-zero emission mobility. Further research and testing are underway to fully realize the benefits of this powertrain configuration in the transition to a more sustainable transport ecosystem.