Particulate and emissions regulations suggest that methanol fueled diesels need to be investigated as an alternative to control technologies. Methanol has a high autoignition temperature, and requires a system to improve its ignition. A promising solution is to use an on-board catalytic reactor to generate dimethyl ether (DME) from the methanol fuel. The DME is aspirated into the engine, and ignites the main methanol charge. In phase I, it was shown that ignition angle can be adjusted by controlling the DME concentration. Maximum cylinder pressures and rates of pressure rise were compatible with current engine designs. Exhaust concentrations of CO and hydrocarbons were slightly increased, although the absolute levels were still low. The mechanism by which DME ignites the methanol was identified, and a preliminary DME reaction mechanism was developed. In Phase II the functional relationship between DME concentration, ignition angle, emissions, and engine efficiency will be determined. A control system will be developed and the entire system tested using a steady-state approximation to the EPA transient test cycle with bottled DME. The mechanism responsible for the low temperature ignition of DME will be determined and combustion modelling to support system development will be carried out. The research addresses the key problem in methanol diesel engines; unacceptably long ignition delay. This technology makes possible use of methanol to meet particulate standards, without requiring extensive engine modifications or expensive fuels. Significant interest has been expressed by the major diesel manufacturers.
