The optimised mixture formation for hydrogen fuelled engines

Both intake port injection type and in-cylinder injection type hydrogen fuel supply systems are designed for a single-cylinder research engine to investigate the effect of mixture formation on the performance of the hydrogen-fuelled engines. The intake port injection is superior in thermal efficiency and engine operation stability at low load conditions. However, the in-cylinder injection is superior for high load condition. In an engine experiment with throttling condition, the engine with intake port injection operates more stably and efficiently when fuel–air equivalence ratio is maintained above a certain level despite the pumping loss due to stable combustion. Thus, the hydrogen-fuelled engines can be operated more stably with the in-cylinder injection at high load and more efficiently with the intake port injection at low load. Therefore, the optimised operation of the hydrogen-fuelled engines can be achieved with a dual injection system and throttle valve control.