The Effect of Ceramic Thermal Barrier Combustion Chamber Coatings on the Performance and Efficiency of a Small Diesel Engine

This study considers the relatively high fuel consumption of small-displacement Diesel engines and seeks to improve it through thin ceramic thermal barrier coatings. A small displacement (219 cc) single-cylinder direct-injection production Diesel engine is utilized. A Ricardo WAVE simulation is developed and suggests that through simultaneous application of the coatings and reduction of compression ratio, the fuel consumption can be improved through a reduction in thermal losses. At the stock compression ratio, the application of thermal barrier coatings does not improve fuel consumption unless injection timing is carefully controlled. When injection timing is also adjusted, fuel consumption can be improved by up to 10%, particularly at low loads, with application of the thermal barrier coatings. The data show higher rates of energy release, higher peak pressures, leading to the lower fuel consumption. When coatings are combined with simultaneous reduction in compression ratio and injection timing adjustment, fuel consumption remained similar at low loads but increased at high loads due to delayed combustion phasing and increased exhaust sensible enthalpy loss. However, these data suggest that an engine with lower compression ratio could achieve similar fuel consumption with thermal barrier coatings, thus allowing a smaller and lighter engine to be utilized, which enhances mobility of these small diesel power plants.