Optimization of the effect of thermal barrier coating (TBC) on diesel engine performance by Taguchi method

In this study, thermal barrier layers were coated on piston and valve surfaces using plasma spray method. The effects of coated layers on torque, power and brake specific fuel consumption (BSFC) were investigated experimentally, and statistically using the Taguchi optimization method. Coating materials used in this study were Al2O3+ 13% TiO2, Cr2O3, and Cr2O3+ 25% Al2O3. Each coating material was tested at different speeds, which were 1400 rpm, 2000 rpm, 2600 rpm and 3200 rpm. The results showed that engine torque and BSFC reached their optimum values with the use of Al2O3+ 13% TiO2 at the speed of 2600 rpm. However, engine power showed the best performance with the same coating material but at the speed of 3200 rpm. The results of the experiment were also tested using Taguchi optimization method with coating material and engine speed parameters. The design of Taguchi analysis was carried out with L-16 (4(2)) orthogonal array. The highest S/N ratios of engine torque and BSFC were observed with the coating material of Al2O3+ 13% TiO2 at the speed of 2600 rpm. However, the highest S/N ratio of engine power was seen with the use of Al2O3+ 13% TiO2 at the speed of 3200 rpm. In order to determine the statistical significance of experimental parameters on engine torque and power and BSFC, ANOVA and F-test were carried out. The results of statistical analysis showed that the coating materials (P < 0.05) and engine speed (P < 0.05) parameters were statistically significant on the engine torque, power and BSFC.