Investigation of Running HCCI With Dual-Fuel in a Small Scale Engine

Homogeneous charge compression ignition (HCCI) is a well-known technology that reduces the fuel consumption and exhaust emissions. This work implemented HCCI on a 150cc spark-ignition (SI) engine. The compression ratio of target engine was changed from 10.5 to 12.4 to enhance the compression temperature. In addition, a commercialized low-pressure injector was installed near the intake port for supplying fuel for HCCI operation. After the analysis of in-cylinder gas temperature, the dual fuel, with gasoline for the additive fuel and kerosene as the main fuel, was investigated in the small scale target engine. Experiments were executed through various excess air ratios, different gasoline additive ratios and then extension of engine load. Two-stage heat release, which provides energy to heat up the mixture during the compression stroke, was observed from HCCI combustion with kerosene fuel. The maximum rate of pressure rise (MRPR) could be reduced by increasing gasoline additive ratio of dual fuel without deteriorating the engine power output. By using the dual fuel method, the engine indicated mean effective pressure could be improved by a maximum percentage 23.9% and an average percentage 17.6% from just using kerosene fuel under the knocking limitation of MRPR equals to 4 bar/deg.