Experimental investigation of thermal swing piston insulation at single cylinder gasoline engine

The reduction of carbon dioxide emissions and the corresponding increase in gasoline engine efficiency are crucial in engine development. Wall heat losses are a major cause of efficiency loss, accounting for 15–30% of the total fuel energy. One promising solution is the use of "thermal swing" coatings at the combustion chamber walls because of offering the possibility that the surface wall temperature following the working gas temperature, whereby the wall heat transfer can be reduced at any time during the engine cycle. This type of coating material is characterized by low thermal conductivity and, at the same time, low heat capacity. Based on the idea of the “thermal swing” coatings, yttria stabilized zirconia (YSZ) was selected as the coating material for the piston surface and its efficiency potential was experimentally investigated on a single-cylinder gasoline engine. The use of highly dynamic temperature probes in the piston allowed precise analysis of cycle-based temperature fluctuations, especially on the piston surface. The transmission of the piston temperatures was cable-based and accomplished through the use of a lever system in the engine. The measurement results confirmed the minimal impact on the efficiency that was determined in preliminary simulations. However, the effect of the coating could be established through the measurements.