Performance and Emissions of DI Compression Ignition Engines Fueled with Dimethyl Ether : Performance and Emissions in Retrofitted Engines

Engine performance and exhaust gas characteristics of a direct injection CI engine were investigated with neat dimethyl-ether (DME), and alternative fuel being considered for attaining low emissions. The study was conducted by comparing the new fuel with the conventional diesel fuel. Results from the present work include : (1) It was necessary to add a small amount of lubricating additives to DME in order to achieve satisfactory engine operation, to minimize excessive wear in the injection nozzle. (2) Engine performance for both fuels was mutually comparable. (3) Although negligible amounts of soot and very low THC emissions were measured, NO_x emission was about the same as in diesel fuel operation. (4) The reduction of NO_x emission by retarding the injection timing was highly significant with DME. (5) The NO_x emission form the retrofitted engine could be further reduced by dissolving CO_2 in DME.