Hydrogen Combustion in a Novel Rotary DI-HCRI Engine with Low Heat Rejection

This paper examines the use of radial ignition (RI) at much lower than normal diesel compression ratios (CR's) in a novel direct-injection (DI) diesel rotary-combustion engine (RCE). Unique to this engine are periphery mounted secondary radical generation chambers (mini-chambers) capable of controlling the rates of radical generation. For this preliminary study the engine is operated on hydrogen under conditions conducive to homogeneous combustion RI (HCRI). One goal at the lower CR's normally needed in rotary-engine operations (<10:1) is to see whether HCRI alone can substantially extend the lean burn region of this rotary diesel engine with hydrogen as fuel. The ultimate aim is to enable high-power density operations with both low NO_x emissions and low heat rejection. With these ends in mind a detailed examination is made (via simulation) of the effects of internally generated “radicals” on the combustion chemical-kinetics of this engine. The simulation is based on a formulation that is exceptionally capable of following the combustion, the mass-species transfer and the heat transfer occurring simultaneously in the various main chambers and in the secondary radical generation chambers of the engine.