A Kinetic Investigation on the Effects of Hydrogen Enrichment on Pollutants and Greenhouse Gases Emissions of Gas-fuelled Engines in High Compression Ratio

Nowadays, the world is facing the air pollution and global warming crisis, in which the role of internal combustion engines is significant. On the other hand, in spite of diversities in its composition, compressed natural gas is considered as one of the best choices among alternative fuels. This investigation aims to explore the effects of hydrogen enrichment on formation of pollutants and greenhouse gases in engines working with natural gas at high compression ratios distributed in the city of Tehran. To accomplish this, a previously validated detailed chemical mechanism is embedded with a comprehensive one-dimensional engine model and the results are verified with experimental observations on fuel and air mass flow rates and in-cylinder pressure profile for a single-cylinder gas-fuelled spark ignition test engine, at constant engine speed of 2000rpm and compression ratio of 16. The verified model is then employed for performance and emission predictions under different amounts of hydrogen enrichment. The results indicate that with increase in the volume of hydrogen, the amount of emitted CO, CO2 and CH4 reduces, whereas despite the rise in the maximum in-cylinder pressure, the indicated mean effective pressure decreases.