Second Law Analysis of Gasoline Powered SI Engines with Hydrogen Injection

A simulation study on the effect of hydrogen addition as supplementary fuel to gasoline at lean mixture (equivalence ratio phi = 0.8) was carried out in order to reduce the gasoline fuel consumption and harmful emissions. The effect on the first law, emissions, and second law parameters was investigated. This was done by changing the mixture ratio between gasoline and the supplementary fuels to achieve the required equivalence ratio. The first part (first law and emission performance) was conducted for all engine speeds. The second part (second law analysis) was done at the rated speed of 2750 rpm. The simulation study was performed using the date for (Ricardo E6/T variable compression ratio engine), which was used for model verification. The study showed that at lean mixture, hydrogen addition reduced carbon monoxide and nitrogen oxides levels. Hydrogen addition significantly improved the heat release rate; however, due to its fast burning speed, the heat released was close to the top dead centre compared with gasoline. From second law analysis, hydrogen addition caused a slight drop in the work availability, increased availability loss with heat, and an increase in the area under temperature entropy diagram.

Automated summary

The study demonstrated that adding hydrogen to lean fuel mixtures can reduce carbon monoxide and nitrogen oxide levels, while improving combustion efficiency. However, hydrogen combustion has a faster burning speed compared to gasoline, resulting in slightly different heat release characteristics.