This article represents the results of a single cylinder engine using specially designed electronically actuated fuel injection system fuelled with neat CNG, and mixtures of hydrogen in natural gas (HCNG) of 5, 10, 15 and 20% by energy. Experiments were conducted with wide open throttle and varying the equivalence ratio. Hydrogen which has fast burning rate, when added to compressed natural gas enhances its flame propagation rate. This was reflected in drastic improvement in emission characteristics and increase in lean burn limit. The emissions of HC, CO, decreased with increasing percentage of hydrogen but NOx was found to increase. With the increase in hydrogen supplementation, brake thermal efficiency increased and maximum brake torque timing decreased at similar equivalence ratio. The combustion analysis conducted showed that hydrogen supplementation shifted the peak pressure towards TDC and increased the heat release rate.
Keywords: emissions, IC engines, compressed natural gas, CNG, hydrogen supplementation, engine performance, combustion, fuel injection, flame propagation, brake thermal efficiency, brake torque timing, heat release rate, alternative fuels