Engine Performance and Exhaust Characteristics of Direct-injection Diesel Engine Operated with DME

Neat dimethyl ether (DME), as an alternative fuel candidate for Diesel engines, was investigated by measuring primarily engine performance and exhaust gas characteristics. In addition, other responses of the engine to the new fuel were also determined at the same time, including the injector needle lift and heat release. The engine measurements with this fuel were compared with those obtained by using conventional Diesel fuel.

Findings from the present work include: (1) It was necessary to add a small amount of lubricating additives to DME, if a conventional fuel injection system is employed. This was to achieve satisfactory injector performance and to minimize some excessive wear. (2) Engine performance for both fuels was basically comparable to each other, except for a better energy conversion efficiency with DME. (3) In the DME-operated engine, emissions of soot and unburned hydrocarbon (THC) were almost negligible, but NOx emission was about the same as in the Diesel oil operation. (4) The reduction of NOx emission by delaying the injection time was highly significant with DME.