An HCCI combustion engine system using on-board reformed gases of methanol with waste heat recovery: ignition control by hydrogen

Adjusting a proportion of two fuels with different ignition properties is an effective technique for controlling the ignition timing in HCCI combustion. This research newly proposes an HCCI combustion engine system fuelled with dimethyl ether (DME) having a high cetane number and methanol-reformed gas (MRG) having a high anti-knock property. In the system, both DME and MRG are to be produced from methanol by onboard reformers utilising the exhaust heat from the engine. Because the reactions producing DME and MRG are endothermic, a part of exhaust heat energy can be recovered during the fuel reforming process. This research experimentally investigated characteristics of combustion, exhaust emissions, engine efficiency and overall thermal efficiency including the waste heat recovery through the fuel reforming in the HCCI combustion engine system. Because MRG consists of hydrogen and carbon monoxide, effects of the two on the autoignition of DME were also analysed.