Numerical Simulation of Surface Temperature Fluctuation and Thermal Barrier Coating at the Piston Top for a Diesel Engine Performance Improvement

Low heat rejection (LHR) combustion has been recognized as a potential technology for further fuel economy improvement. This paper aims to simulate how the piston top’s thermal barrier coating affects the engine’s thermal efficiency and emissions. Accordingly, a Thin-wall heat transfer model in AVL Fire software was employed. The effects of increasing the piston top surface temperature, comparing different thermal barrier coating material, were simulated at the engine’s rated power operating point, so as the piston top’s surface roughness. In comparison to a standard diesel engine, the indicated thermal efficiency (ITE) could increase by 0.4% when the surface temperature of the piston top changed from 575K to 775K. Comparing among the different coating materials, SiRPA (quartz reinforced porous anodic alumina), Zirconia (zirconium oxide), and YSZ (yttria-stabilized Zirconia), SiRPA was found to be the most effective one in term of thermal flux reduction, which could promote ITE by 0.8%. The simulation also showed the piston top’s roughness after coating should not be neglected. It suggested that to minimize the surface roughness of the thermal barrier coating would be beneficial for the engine ITE improvement. The result of this paper will be a useful reference for the LHR combustion system design and optimization.