Use of CNG and Diesel in CI Engines in Dual Fuel Mode

Presence of smoke in diesel engine exhaust is an indication of poor combustion due to several factors. Nevertheless, with an ever increasing concern for the impact of air pollution on environment, animal and plant life, vehicle exhaust emissions, particularly due to road transport, have, in recent years been subjected to increasingly stringent regulations. The environmental pollution can be controlled by utilization of clean fuel such as CNG (Compressed Natural Gas). The present work was carried out on a 7.35 kW four-stroke, twin cylinder, direct injection (DI) diesel engine which was operated in dual fuel mode with substitution of up to 75% diesel with CNG. It was observed that the substitution of CNG reduced the noise level, specific fuel consumption, NOx, however increased the unburned hydrocarbons.