低カロリーおよび組成変動の生じるガス燃料を利用するエンジンシステムに関する研究

抄録

The internal combustion engines are required to use various fuels, fuels from biomass, shale gas and etc. to reduce the dependence on petroleum resources and to ensure enough energy. The composition of such fuels varies and its energy density is lower than traditional fuels used in engines. The author has been studying to use such fuels in stable and higher thermal efficiency from the view point of the engine control, advanced combustion technology and multi-fuel combustion with traditional fuels. This paper introduces such activities. The engine control system of a conventional spark ignition engine to use the gas fuels from biomass, its composition vary during engine operating, has been developed. The control system can set an optimum pre-mixture condition and an ignition timing for the fuels, which realizes a stable and high-thermal-efficiency operation automatically. To realize higher thermal efficiency, applicability of such fuels to an HCCI engine, ignition and combustion characteristics were investigated in an HCCI engine. It is clarified that HCCI combustion is available for such fuels and the ratio of H₂ to CO₂ in the fuels is useful to predict the combustion speed. The gas fuels are also applied to a diesel engine and the effect of H₂ of gas fuels on ignition and combustion was investigated. Higher H₂ content gas fuels realize higher thermal efficiency and stable combustion even if the amount of injected diesel fuel is small.