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A novel way of using low-cetane-number petroleum gases in a compression ignition (CI) engine is introduced, by directly injecting blends of such fuels with dimethyl ether (DME), a high-cetane-number alternative fuel for low soot emissions. This method both extends advantages of DME and complements its deficiency. Although DME mixes with most hydrocarbon fuels in any ratio, in order to demonstrate the feasibility of the new method and facilitate the analysis, DME-propane blends were investigated in a direct injection CI engine. Some findings of the study are listed. In the engine operated by DME and propane blends, there was no need for significantly increasing the complexity of the fuel system than that employed in the use of neat DME. For the same reason, this method eliminates or minimizes cumbersome hardware necessary when the said gaseous fuels are separately introduced in CI engines.

An experiment was conducted with a direct injection Diesel engine operated with neat dimethyl ether (DME). Main focus of this research is to investigate the performance of the catalysts designed for NOx reduction, such as Co–alumina and Sn–alumina catalysts, for the reduction of NOX and other unburned species contained in the exhaust gas. In the experiments, DME concentration in the exhaust gas was changed by adding extra DME before the catalytic reactor, which is the important experimental parameter in the research. Results showed that NOX reduction rate was not so high without any DME addition, because the content of unburned DME, reducing agent, is very low in the DME engine exhaust gas. However, NOX reduction rate increased with increase in DME content and it reached around 80% with enough DME addition. The NOX reduction rate increased with increase in reaction temperature up to around 300 °C.