Thermal Barrier Effects on Performance and Emissions of a Methanol Fueled Dl Engine

Direct injection stratified charge (DISC) engines have much potential for tolerating the broad range of properties encountered in modern alternative fuels, while maintaining acceptable efficiency and performance levels. In practice these engines experience low combustion efficiency at light loads, leading to degraded performance and excessive unburned fuel emissions. A comparative test program was carried out to investigate the potential for improving upon these limitations in a methanol fueled DISC engine by employing a thermal barrier coating in the primary combustion chamber. The results indicate that the potential for improvement was likely small or difficult to perceive due to heavy friction losses in the engine/dyno tandem. Emissions were generally in accord with previously published data and unburned fuel continued to be prevalent at low loads. Additional work should focus on more aggressive insulation techniques and optimization of injection/ignition parameters.