Toward achieving a low-carbon/carbon-neutral society, Mitsubishi Heavy Industries, Ltd. is promoting the development of a methanol-diesel dual-fuel engine with a view to introducing it as a marine main or auxiliary engine. Among the carbon-neutral fuels, methanol is easier to handle than hydrogen or ammonia. While being a promising alternative fuel for marine vessels, methanol poses technological challenges of coping with combustion fluctuations and minimizing unburned methanol emissions. Using diesel pilot ignition for the combustion system, CFD analysis was conducted to optimize the formation of the fuel-air mixture and investigate the combustion behavior in detail. A single-cylinder test unit was used to verify the effect of combustion control; the results confirmed that the issues of combustion fluctuation and unburned methanol emission can be considerably mitigated. By developing these findings into a multi-cylinder unit for practical use, we aim to help make a carbon-neutral society a reality.
