The paper presents energy and exergy based analyses of a single cylinder, four-stroke, spark ignition engine fuelled by six different fuels namely iso-octane, methane, hydrogen, methanol, ethanol and n-butanol. Wiebe function is used to predict realistic burn rates. Since the Wiebe function parameters are generally optimized for conventional fuels, the current study modifies them for different alternative fuels using available burning velocity data. Heat losses throughout the cycle have been predicted by empirical correlations. Analyses are carried out to quantify energy and exergy of the premixed fuel-air mixture inside the engine cylinder at various phases of the cycle and some results obtained from the study are validated against data available in literature. Both energy and exergy destructions are found to be dependent on the fuels and engine operating parameters. Results show that at 1000 rpm, about 34–39% of energy contained in the fuel is converted into useful work and this quantity is found to increase with engine speed. Exergies associated with exhaust are found significantly lower than the corresponding energy values for all fuels. The present study highlights the necessity of both energy and exergy analyses to probe and identify the sources of work potential losses in SI engines in various phases of the cycle.
