Abstract
Keywords:
Emission, Direct Injection, Lean Burn, Natural Gas Engine, Stratified Mixture, Injection Timing
Abstract
A CNG fuel is one of the most promising alternative fuels because of lower exhaust emissions and lower CO2 emission with high thermal efficiency. However, the brake horse power is reduced because a CNG fuel has a low volumetric efficiency due to the gaseous charge and increase in time losses with lower burning speed as compared with gasoline fuel. To solve these problems, the DI Diesel Engine was modified to the DI CNG engine which directly supplies natural gas into the engine cylinder. The combustion characteristics of the DI CNG engine such as cylinder pressure, cycle variation, combustion duration and emissions were investigated in this study. Consequently, it could be verified that the volumetric efficiency, overall combustion duration and lean limit were improved by using DI technique in the CNG engine.