Influence of Reformed Gas Composition on HCCI Combustion Engine System fueled with DME and H2-CO-CO2 which are Onboard-reformed from Methanol Utilizing Engine Exhaust Heat

Abstract

One of the authors has proposed an HCCI combustion engine system that was fueled with dimethyl ether (DME) with a high cetane number and methanol-reformed gas (MRG) with a high anti-knock property in the previous research. In the system, both DME and MRG are to be produced from methanol by onboard-reformers utilizing the exhaust-heat from the engine. High overall thermal-efficiency has been achieved over a wide operable-range by both the lean HCCI combustion and the waste-heat recovery. While the MRG used in the research was the thermally decomposed methanol, methanol can be reformed to various compositions of hydrogen, carbon monoxide and carbon dioxide. This research aims to find the optimum MRG composition for the system in terms of the ignition control and the overall thermal efficiency. Characteristics of the HCCI combustion of DME and four types of MRG model-gases are experimentaly analyzed. The overall thermal-efficiency was also evaluated for ideal reforming conditions for each case.