Abstract
In this paper, combined first and second law approach is applied to investigate the effects of percent excess air and ambient temperature on the energy and exergy efficiency of the hydrogen-fuelled homogeneous charge compression ignition engine. A maximum energy efficiency of 45% and an exergy efficiency of 37% are obtained at the excess air of 25%. A narrow range of 42-40% energy efficiency and a wide range of 25-45% exergy efficiency were achieved between the 20-40% excess air and an ambient temperature of 300 K. Close range of variation for energy efficiency (48-44%) and exergy efficiency (32-36%) were achieved between the ambient temperatures of 13 degrees C and 41 degrees C. Exergy analysis indicates that 52% of the fuel hydrogen exergy is destroyed due to various irreversible processes of the engine, around 40% is available as a useful work output, and 7.83% is lost via engine exhaust.