Science and Technology of Energetic Materials

Vol.73, No.2 (2012)

Research paper

Reduction of Diesel Engine Emissions Using Hybrid Combustion
Kouhei Hatada, Akira Kakami, Shigeki Hirashima, and Takeshi Tachibana


We propose a new method to apply hybrid fuel combustion to diesel engines in order to reduce NOx and smoke emissions. In hybrid combustion, subsidiary fuel is fed into intake air, whereas the main fuel of light-oil is directly injected into the combustion chamber as in conventional diesel engines. In this study, we tried to use two different kinds of fuels, di-methyl ether (DME) and gasoline as subsidiary fuels. DME, with a high cetane number and excellence in auto -ignition, is used only to afford preliminary combustion in the early compression period, which promotes and advances the ignition of the sprayed main light-oil and accordingly reduces emissions. Gasoline, by contrast, with no self-ignition characteristic in diesel engines, is used as a part of the main fuel to fill the engine cylinder with a uniform mixture before the injection of diesel fuel, the other main fuel, to ignite both the main fuels smoothly and lower emissions. Experiments with DME demonstrated successful ignition earlier than the conventional method and decrease of NOx from 160 to 120 ppm without smoke increase at 2 NL/min DME flow. Use of gasoline as the complementary main fuel eliminated smoke emissions and reduced NOx from 2700 to 1600 ppm.


hybrid combustion, diesel engines, subsidiary fuel, di-methyl ether (dme), gasoline, emission reduction

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