The possibility of the SI engine CO2 emission reduction with the application of CNG-hydrogen blends

The influence of hydrogen-methane blends application in SI engines on their CO2 emission is the main goal of this paper. The 1.6 litre engine alternatively fed with either petrol, CNG and with methane-hydrogen blends has been tested in the research program. The possibility of passenger car engine operation on H2-CH4 mixtures has been demonstrated in the paper, with the underlining of the potential of those mixtures in the increasing of the engine efficiency. Necessary changes in strategy of engine regulation, especially in air/fuel ratio, ignition advance and EGR rate, were noticed and prepared. The methane-hydrogen blends, which were used in the research programme featured ratios as follows: 5%, 10% and 15% of hydrogen. For selected engine operating points, following data has been acquired: in cylinder pressure variation, crank angle, manifold pressure and finally mass fuel consumption. On the basis of registered data for all fuels - burned temperature in cylinder has been estimated, as well as the charge combustion ratio, and the heat release rate. With help of mathematical model describing the exhaust gases formation it has been possible to estimate the NO, CO and CO2 emission level. Obtained results made it possible to compare the combustion process for all tested fuels and pointed on the significant influence of hydrogen percentage for the methane-hydrogen blends, on the CO2 emission reduction up to 20%. Negative aspects of chosen blends application have been also describe in the paper, especially of increasing engine thermal load.