Abstract:
This research is an investigation into the performance and combustion characteristics of
a two-cylinder, four-stroke compression ignition engine fuelled on diesel and then on
dimethyl ether (DME). Baseline tests were performed using diesel. The tests were then
repeated for dimethyl ether fuelling. All DME tests were performed at an injection
opening pressure of 210 bar, as recommended for diesel fuelling. The tests were all
carried out at constant torque with incremental increases in speed and an improved
method of measuring the DME flow rate was devised. It was found that the engine’s
performance characteristics were very similar, regardless of whether the engine was
fuelled on diesel or DME. Brake power, indicated power and cylinder pressure, during
the highest loading condition of 55 Nm, were virtually identical for diesel and DME
fuelling, with the most significant finding being that the engine was more efficient when
fuelled on DME than when fuelled with diesel. Another interesting finding was that the
energy release of diesel decreases with increasing load, whilst the energy release of
DME increases with increasing load. At the highest loading condition of 55 Nm, the
energy release of DME was approximately 210 joules higher than that of diesel. This
investigation concluded that DME may definitely be a suitable substitute fuel for diesel.
