Energy loss and comprehensive performance analysis of a novel high-efficiency hybrid cycle hydrogen-gasoline rotary engine under off-design conditions

Abstract

The rotary engine is a potential power device for unmanned aerial vehicle. In this paper, a novel X-type hydrogen-gasoline rotary engine using high efficiency hybrid cycles (HEHCs) is proposed to realize the high efficiency and low carbon dioxide emission. Firstly, the zero-dimensional single-zone models are established for the X-type rotary engine using theoretical (ideal cycle and ideal working fluid of air), ideal (ideal cycle and real working fluid) and real (real cycle and real working fluid) HEHCs. The type I and II losses are introduced to indicate the energy losses from theoretical HEHC to ideal HEHC and from ideal HEHC to real HEHC, respectively. Furthermore, the effects of hydrogen doping fraction of gasoline-hydrogen hybrid fuel, ignition angle and rotational speed on type I and II losses are studied. Finally, the variation trends of cycle efficiency, indicated power, indicated fuel cost and indicated carbon dioxide emission (ICDE) are revealed under different operation conditions. The results show that the increasing hydrogen doping fraction rises the type I and II losses, while the increasing ignition angle or rotational speed declines the above losses. The maximum cycle efficiencies of real HEHC with pure gasoline and hydrogen doping fraction of 0.3 are 42.6% and 41.5% at the optimal ignition angles of 330° and 345°, respectively. The cycle efficiency of real HEHC is increased by 1.3% at the rotational speed of 9000 rpm with the increase of hydrogen doping fraction of 0.3. The indicated fuel cost and ICDE for the hydrogen doping fraction of 0.3 is 19.2% higher and 28.2% lower than that for pure gasoline under optimal ignition angles, respectively. The increasing hydrogen doping fraction reduces the effect of rotational speed on the cycle efficiency, indicated fuel cost and ICDE.