Experimental optimization of the performance and energy distribution of a direct injection hydrogen engine with analysis of application to onboard hydrogen storage methods

Hydrogen internal combustion engines (H₂ICE) and proton exchange membrane fuel cells (PEMFC) have been proven to offer high thermal efficiency and sufficient power density for light-duty vehicles. Gaseous, high-pressure, compressed hydrogen is widely used for onboard hydrogen storage, but its low storage density and the high-security risk are a concern. Other hydrogen storage methods have advantages in safety or density but require high heated temperatures or large dehydrogenation energy which is difficult for PEMFC. However, higher exhaust temperatures of over 400℃ and energy from hot (∼100℃) coolant from H₂ICE provide the potential for applying other hydrogen storage methods. In this paper, the performance of a 2.0 L turbocharged direct injection H₂ICE was optimized by applying a variable geometry turbocharger (VGT) to gain better intake flow with a high power of 124.8 kW. Effects of five significant parameters of engine speeds, intake valve timing, VGT opening, injection timing, and intake pressure are explored using 1st and 2nd law energy balance analysis to gain the maximum BTE of 43.03 %. The potential of various hydrogen storage methods is evaluated by comparing onboard hydrogen producing temperature and required exergy against that available from the engine. The availability of applying new onboard hydrogen storage methods including all physical storage categories and some material storage methods has been demonstrated.