Abstract
The goal of hydrogen engine research is to achieve highest possible efficiency with low NOx emissions. This is necessary for the hydrogen car to remain competitive with the ever improving efficiency of conventional fuel’s use, to take advantage of the increased availability of hydrogen distribution for fuel cells and to achieve better range than battery electric vehicles. This study examines the effect of compression ratio (CR) and lambda (excess air ratio) on thermal efficiency for CRs of 13, 14.5 and 16. The results demonstrate that highest indicated thermal efficiency at ultra lean condition of lambda around 2 at the optimum CR of 14.5 which was higher than for LPG by nearly 3 CRs. The efficiency, although comparable with or better than other good hydrogen engine practice, did not increase much over LPG. This is explained by the expected higher heat transfer losses. At CR 14.5, and MBT spark and at frequently used torque and speed conditions in the NEDC, the highest brake thermal efficiency was 39.9 to 40.8% at a maximum indicated thermal efficiency of 48%.
KEYWORDS: SI Engine, hydrogen, efficiency, compression ratio, turbocharger