The multi-criteria decision-making method was used to comprehensively evaluate exhaust gas emission characteristics of a diesel engine, while gasoline fumigation was added to reduce pollutant emissions under diferent operating conditions, namely engine loads (1.9–6.2 bar) and engine speeds (1300 and 2000 rpm). Experiments were performed on a multi-cylinder diesel engine with a mechanically controlled fuel injection pump. The experimental results show that using partially premixed gasoline, the specifc NOx and CO2 emissions decrease to about 28 and 7% (averaged over all engine loads), respectively, in comparison with the pure diesel case, while smoke opacity decreases up to 50% at high loads with premixed gasoline. However, increase in the specifc CO and HC emissions has been found by applying the same strategy at all loading conditions. The optimum conditions with desirable or minimum emissions characteristics were operation modes with gasoline fumigation at 2.1 bar engine load for 1300 rpm and at 3.8 bar engine load for 2000 rpm. Thus, gasoline fuel as premixed fuel with the fumigation method showed a favorable potential in terms of reducing the main emissions in diesel engines.

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