Improved efficiency of CNG using hydrogen in spark ignition engine

Experimental investigations carried out on a single-cylinder four-stroke motorcycle spark ignition engine operating on gasoline and natural gas are reported in the present paper when compressed natural gas (CNG) and hydrogen were used as fuel. The investigations were carried out by mixing a small percentage of hydrogen (5 to 30%) with CNG and supplied to the engine. Hydrogen and CNG were mixed in a developed mixer and supplied through the inlet manifold system. Performance and emission tests carried on the engine with this system showed a considerable improvement in power output and in thermal efficiency as well as reduction in brake specific energy consumption (BSEC), hydrocarbon (HC) and carbon monoxide (CO) emissions. Power loss associated with CNG utilization had improved with the addition of hydrogen fuel (20 to 30%) was observed. The combustion analysis was carried out for different rates of hydrogen addition. The rapid rate of burning of CNG-air mixture with the addition of hydrogen showed higher energy release rate, leading to higher cylinder pressures. Hydrogen blended with CNG enabled leaner operation and showed an improvement in BMEP and environmental benefit.