On the modeling of a SI 4-stroke cycle engine fueled with hydrogen-enriched gasoline

A detailed model to simulate a four-stroke cycle of a SI engine fueled with hydrogen-enriched gasoline is presented. The model includes calculations of the mass flow rates of the inflow and outflow through the valves, an empirical expression for the combustion process which has been modified to include the effect of the hydrogen enrichment on the combustion rate, a model for the ignition delay, a practical approach for the heat transfer through the cylinder wall, and an SAE recommended expression for the mechanical efficiency. The model has been used to predict the optimal amount of hydrogen supplement, and the required spark advance for best engine performances. Dynamometer test results, in which a 2310 cc passenger vehicle was fueled with hydrogen-enriched gasoline, was used to calibrate the proposed model. The hydrogen was supplied from a bottled storage of gaseous hydrogen. In general, very good agreement between predictions and experimental results was obtained in the entire experimental range.