Experimental analysis on combustion, performance and emission characteristics of exo-THDCPD/diesel blends in a compression ignition engine

High-energy-density fuel exo-tetrahydrodicyclopentadiene (exo-THDCPD) has high density and calorific value, which has the potential to be used as an extended-range fuel to improve the maneuverability and endurance of ground vehicle equipment. The present experiment aimed to investigate the combustion, performance and emission characteristics of different exo-THDCPD/diesel blends to explore the feasibility of its application in diesel engine. The test fuels were prepared on volume basis and named as follows: ED5, ED10, ED15, ED20 and ED25. The tests were carried out on a six-cylinder, four-stroke, naturally aspirated and direct injection diesel engine. It was observed that the blends had higher brake thermal efficiency, torque compared to pure diesel, while lower brake specific fuel consumption. Combustion analysis indicated that exo-THDCPD/diesel blends had longer ignition delay, shorter combustion duration, higher in-cylinder pressure and heat release rate, suggesting improved combustion. Furthermore, the coefficient of variation in maximum in-cylinder pressure and the coefficient of variation in indicated mean effective pressure increased as exo-THDCPD ratios increased, but all the values were no more than 5%, indicating a relatively stable combustion. In terms of exhaust emissions, nitrogen oxide, unburned hydrocarbon and carbon monoxide emissions increased significantly with exo-THDCPD/diesel blends compared to pure diesel, while soot emissions decreased.