Graphical exergy analysis of a chemically recuperated diesel engine

A graphical exergy analysis has been applied to a traditional high-speed, naturally-aspirated, four-stroke diesel engine and the energy utilization diagrams of different working processes have been drawn in this paper. Results show that the most destruction of exergy occurs in the combustion process because the difference of energy level between fuel and working medium is very large. The same analysis method has also been applied to a chemically recuperated diesel engine. Calculation results show that the relative exergy destruction of the combustion process will decrease by 5.68% when the volume flow rate of syngas injected into cylinder for burning is 10% of the fresh air. As a conclusion, chemically recuperated diesel engines have a better cascade utilization of fuel energy compared to traditional diesel engines by combining the combustion reactions with the fuel steam reforming reactions.