Effects of different piston combustion chamber heights on heat transfer and energy conversion performance enhancement of a heavy-duty truck diesel engine

Abstract

The heat transfer and energy conversion characteristics of 3 kinds of pistons are studied based on the heat load prediction model of diesel engine piston. Thermal energy conversion effects of pistons for heavy-duty truck engine performance are investigated which involve air-fuel ratio, intake flow, exhaust temperature and fuel consumption. The research results illustrate the whole temperatures and heat flux of piston rise with increase of piston combustion chamber height. The maximum and the minimum temperature difference are 18.34 K and 3.07 K of piston-12, piston-15 and piston-18 with the piston wall surface temperature change dramatically. Maximum heat flux (1 203 500 W/m2, 1 488 500 W/m2, 1 523 200 W/m2) and the minimum heat flux (761.37 W/m2, 990.41 W/m2, 1325.2 W/m2) of piston-12, piston-15 and piston-18 are conspicuously conspicuously different with piston wall surface heat flux significant change. Piston-18 has the characteristics of large air-fuel ratio (27.3) and intake flow (844.33 kg/h), low fuel consumption (217.3 g/kW·h) and exhaust temperature (776.8 K), which shows that it is more efficient and the heat energy conversion capability is improved remarkably. The appropriate piston chamber height can improve heat transfer and energy conversion performance.