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Since dimethyl ether (DME) is a synthetic fuel, it is possible to make it from natural gas, coal and biomass. It is a low-emission, oxygenated fuel, which does not generate soot in the exhaust. Therefore, it has recently been identified as a possible replacement for diesel fuel. In Japan, the new short-term emissions regulations will be enforced beginning in 2003, and the long-term emissions regulations are scheduled to be enforced in 2005. In order to meet these more stringent emissions regulations, existing diesel engines would not be as widely used in the near future as they currently are. This will thus bring about a more widespread use of DME engines due to their low emissions potential. Moreover, when the modification of existing diesel engines into DME engines is available at a moderate cost, the wider use of DME engines can be expected. This study targeted development and application of DME engine technology for diesel engine retrofit, in a used diesel vehicle.

In order to reduce environmental disruption due to exhaust PM and NOx emissions from diesel engines of dimethyl ether (DME) has been proposed the use for the next generation vehicles, because the discharge of the atmospheric pollutants is less. In this study, DME is used to fuel a retrofit type diesel engine, and operational tests were carried out using a rotary distributor fuel injection pump. In this experiment, comparison and examination of the effects of fuel injection pressure, nozzle hole diameter, and injection timing. When using DME as an alternative fuel, the fuel temperature affects engine operation. And diameter of the injector nozzle hole and larger injection quantity is regarded as factors affecting the improvement in engine performance. In addition, for understanding the DME spray in the cylinder, DME was sprayed in a constant volume chamber where atmospheric temperature and pressure increased simultaneously, and the result is compared and examined with diesel fuel.