The experimental study on combustion characteristics and emissions of a CMM fueled engine

In this paper,an experimental study on combustion characteristics and emissions of a single cylinder spark ignition engine fueled with coal-mine methane(CMM)is investigated under various loads.CMM is simulated by the compressed nature gas(CNG)/nitrogen blend fuels.Based on ex-periment results,it is shown that under 0%～35% nitrogen volume fraction in CNG/nitrogen blends,the maximum cylinder pressure,the maximum rate of pressure rise and the rate of heat re-lease decrease,the flame propagation period increases,the center of heat release curve is closed to the top dead centre(TDC)markedly with the increase of nitrogen volume fraction.Meanwhile,the hydrocarbon(HC),CO emissions increase,the NOx emission decreases apparently with the in-crease of nitrogen volume fraction.