Analysis of thermal coating on Engine performance parameters & fuel economy of a small size NA spark ignition engine

With strict upcoming regulation norms, it becomes a challenging task for automotive industry to develop highly efficient engine that meets all the regulation norms. The focus of automakers is to utilize fuel energy in most efficient way and to reduce the energy loss from the engine to improve thermal efficiency. Heat loss to the cooling medium is one of the prime losses inside the combustion chamber. Thermal barrier coating is used to reduce heat losses across combustion chamber surfaces (Piston, head, valves and cylinder liner) as it provides good insulation because of the prominent properties of coating materials like low thermal conductivity, low heat capacity, high melting point etc. This paper presents application and impact of thermal swing coating on thermal efficiency and engine emissions. The benefit of reduction in heat loss across the combustion chamber surfaces leads to increase in thermal efficiency without deteriorating volumetric efficiency since thermal swing coating material follows gas temperature quickly throughout the cycle. An initially developed physics based engine simulation model for three cylinder naturally aspirated SI engine in GT POWER was used to examine the impact of coating on thermal efficiency and emission characteristics. Thermal swing coating was applied on piston’s top surface, head and valves. Initially single point analysis was done at 2000 RPM and 4 BMEP with coating and without coating. The study was extended for MIDC cycle and performance of uncoated and coated model were compared. From the energy balance analysis, it was found that engine thermal efficiency and fuel efficiency was improved as in-cylinder heat transfer was reduced when coating was applied. Emissions with coating were more controlled than the engine without coating. This study was extended for Natural gas also and Sensitivity analysis of different coating material properties for thermal efficiency is investigated.