Hydrogen enriched CNG - A tool for dual fuel engine overall performance improvement

The potential of hydrogen-methane blends application in dual-fuel SI engines in their overall performance improvement has been evaluated and described in this paper. The 1.6 litre engine alternatively fed with petrol, CNG and with methane-hydrogen blends has been tested. Generated outboard methane-hydrogen blends, used in the research programme featured following hydrogen-CNG ratios: 5%, 10%, 15%, 20% and 30%. For selected engine operating conditions, a complete set of data defining engine overall performance, such as power output, in-cylinder pressure variation, manifold pressure and finally mass fuel consumption has been acquired. On the basis of registered data for all the tested fuels, with the use of mathematical model describing the exhaust gases formation it was possible to estimate the NO, CO and CO₂ emission levels. Obtained results made it possible to compare the combustion processes for all of the tested fuels and to point on the significant influence of hydrogen share in the methane-hydrogen blends, on the CO₂ emission reduction. Complete analysis featured also the evaluation and analysis of the negative aspects of H₂-CH₄ blends application, like the engine thermal load increase.