A comparison of performance and emissions characteristics of an engine fuelled on DME and on diesel with particular interest on injection characteristics

Abstract

This report contains the results of tests conducted on a compression ignition engine which was fuelled on both DME and diesel. The results compare the performance and emissions characteristics of the two fuels. As an addition to the existing test cell setup, an injector lift sensor was added in order for the injection characteristics to be monitored. It was established that the engine requires more fuel when running on DME than on diesel in order to obtain the same power output. This is because DME has a lower heating value as well as density than diesel. DME CO2 emissions were higher than diesel, while DME CO emissions were lower than diesel. The NOx emissions for DME were higher than diesel at lower engine speeds, and then lower than diesel at higher engine speeds. It is suspected that the DME emissions are negatively affected by later injection of DME than diesel injection as well as longer duration of injection for DME than for diesel as this may result in incomplete combustion of fuel.