Experimental Investigation on Performance of Single Cylinder Diesel Engine with Mullite as Thermal Barrier Coating

Abstract

Tests were performed on a single cylinder, four stroke, direct injection, diesel engine whose piston crown, cylinder head and valves were coated with a 0.5 mm thickness of 3Al2O3 .2SiO2 (mullite) (Al2O3= 60%, SiO2= 40%) over a 150 μm thickness of NiCrAlY bond coat. The working conditions for the standard engine (uncoated) and low heat rejection (LHR) engine were kept exactly same to ensure a comparison between the two configurations of the engine. This paper is intended to emphasis on energy balance with and without ceramic insulation coating at identical conditions. Tests were carried out at same A/F ratio for both standard and low heat rejection engine at different engine load and engine speed conditions. The results showed that there was 1.07 % decreasing on specific fuel consumption value of low heat rejection (LHR) engine compared to standard engine at full load. However, there was as much as 16 % decreasing on heat amount to coolant of LHR engine compared to standard engine at full load. There was as much as 22 % increasing on heat amount to exhaust of LHR engine compared to standard engine at full load.