抄録
The aim of this research is to explore a high efficient and low emission engine without persisting in using only a fuel. The authors are currently interested in a natural gas/diesel dual fuel engine with advanced diesel fuel injection control technology which has been developed and adopted for recent diesel vehicles. It is believed that the injection technology would be beneficial for combustion control of the dual fuel engine with high efficient and low emission. In this study, performance of the dual fuel engine was achieved to find out specific characters of the engine. Natural gas was injected into an intake port and diesel fuel was directly injected into a combustion chamber with changing amounts and injection timings of both fuels. The engine test results show that NOx emission got worse along with advancing diesel injection timings to around -40 deg. CA ATDC. However, if injection timings were advanced more, THC and NOx emissions were simultaneously decreased with an increase in indicated thermal efficiency. To deeply understand specific combustion fundamentals acquired through the engine tests, numerical CFD simulations were conducted. For the simulations, a skeletal model for natural gas/diesel dual fuel combustion was developed, and it is clarified that the simulations could reproduce similar combustion behaviors to those taken in the experiments.
