Experimental investigation of combustion characteristics and emissions in a spark ignition engine fuelled with gas in lean operation

This paper proposes an experimental study on the performance and emissions in the lean operation (Phi=0.6-0.7) of a six-cylinder spark ignition engine fuelled with natural gas, pure methane and a mixture of hydrogen in methane (85 CH4, 15%H-2 by volume). Each fuel has been investigated at 1500 rpm and for various load conditions. Emissions, exhaust gas temperature and pressure cylinder were measured. The objective of the study is to determine how the load and equivalence ratio affect engine characteristics operating with natural gas and the hydrogen-methane mixture. The results show that the hydrogen addition increased HC and NO emissions, as well as the performance and cylinder pressure, but reduced the NOx, exhaust gas temperature and the CO and CO2 emissions.