Optimization of Injection Parameters in Compressed Natural Gas Direct Injection (CNG-DI) Spark Ignition Engine

Energy security and environmental problems boosts the development on automotive
industry. CNG as an alternative fuel has been applied in the vehicle to reduce the
engine emissions with drawback in engine performance. It has lower performance
compared to gasoline due to lower volumetric efficiency, lower energy content, and
longer combustion durations. However, high octane number of CNG is beneficial in
increasing engine efficiency. Direct injection application on CNG engine is expected
to increase the volumetric efficiency of the engine to get further increase in engine
performance while still maintaining the low engine emissions. In order to improve the
engine performance, the objectives of this research are investigating the combustion
characteristics of CNG direct injection engine and optimization of injection
parameters to obtain high performance engine.