Exergy analysis of biodiesel combustion in a direct injection compression ignition (CI) engine using quasi-dimensional multi-zone model

In the present work, the exergy analysis was carried out for a diesel engine fueled with waste cooking oil (WCO) and its blends in four-stroke DI (direct injection) diesel engine at full load operation. To model the combustion process, a computerized version of Shahed's quasi-dimensional multi-zone was used. Moreover, a FORTRAN-based code, which includes 12 species (CO2, H2O, N2, O2, CO, H, OH, H2, N, NO, O, Ar) associated with combustion products was employed to study the exergy analysis. The fuel injection amount was kept constant and five different fuel mixtures (B0, B5, B20, B50 and B100) were employed during a closed cycle. The computational in-cylinder pressures for neat diesel fuel were compared with those of calculated experimentally in the literature, and they showed a good agreement. Various rate and accumulative exergy components were computed with crank position at five fuel compositions. The results showed that as biodiesel increases by volume blends from 0% to 100%, the exergy efficiency increases slightly. The accumulative irreversibility decreased by 4.7%. From the viewpoint of the exergy analysis, for considered biodiesel blends the biodiesel fuel could be used as an alternative fuel without any considerable penalty on converting the fuel exergy to thermal energy in order to produce useful work. Moreover, the exergetic performance coefficient showed that B20 was the optimum biodiesel blend to present the best combustion performance.