Combustion temperature and exhaust gas composition in si engine fuelled with gaseous hydrocarbon fuels

This paper presents the issues connected with the process of combustion of natur al gas and methane-hydrogen blend in SI engine. Enriching methane with hydrogen is the way to make the combustion process more efficient and gives possibilities of CO 2 emission reducing. The detailed analysis focused on changes in temperature profile and their impact on thermal charge and composition of the emitted exhaust gas. All the range of investigation is divided into threeparts. First part is dedicated to comparison of combustion temperatures of LPG, CNG and Petrol. In the middle part are presented the results of investigation of influence ignition advance on combustion temperatures of CNG. The third part includes the results of research project aimed at opportunities of efficient combustion of gaseous fuels, whose main constituent is methane. The selected group of fuels included: CNG, and methane-hydrogen blends (with volumetric hydrogen shares - 5%, 10%, 15%, 20% and 30%). The tested engine was an Opel Astra naturally aspirated four-cylinder 1.6 l petrol engine with power output of 55 kW at 5200 rpm and torque of 128 Nm at 2600 rpm. This engine was modified in a way allowing its CNG propulsion without compression ratio variations. The investigations were carried out on chassis dynamometers and were the basis for analysis by means of mathematical simulation model, in this paper. The obtained results were compared to measurements for fuelling with unleaded petrol (95-octane) as a base fuel for this drive unit. Fuelling of engine with blend of methane and hydrogen opens up opportunities for considerable reduction in CO 2. For blend contains 30% of hydrogen the emission of CO 2 was 35% lesser than in petrol case.