Regulated and Nonregulated Emissions from a Dimethyl Ether Powered Compression Ignition Engine

Dimethyl ether (DME) is widely studied to reduce diesel engine emissions, especially the NOx and smoke emissions. However, the DME and aldehyde emissions are seldom studied. In this paper, a two-cylinder, direct injection diesel engine was applied. Pure diesel and DME were used to study the engine emissions, especially the exhaust DME and formaldehyde emissions. Experimental results indicate that DME fuel averagely reduces the CO emissions by 59% and 23.7% at two engine speed. NOx emissions were reduced by 45.2% and 57.9%, separately, in comparison to diesel at two engine speeds. Smoke is almost zero for DME under all the engine operation conditions. The NOx/smoke trade-off correlation was broken. The formaldehyde exhaust concentration from the engine with DME operation is just a little higher than that with diesel fuel. Both engine load and engine speed have little effect on the DME emissions. Because the response of the flame ionization detector to DME is 0.5 times that of Cl and it has no response to formaldehyde, the total hydrocarbon emission of the engine is revised accordingly.