A 3D CFD-FEA co-simulation study of low thermal effusivity TBCs applied to the piston and valves of an SI engine

When applied on combustion chamber walls, thermal barrier coatings (TBCs) with low thermal effusivity provide a pathway for reducing heat transfer and improving SI engine efficiency. A 3D CFD-1D FEA co-simulation routine was employed to study the effects of a proprietary TBC on SI engine performance under different permutations of coating the piston, exhaust valves, and intake valves. Marginal reductions (<0.1% points) in total heat transfer and improvements to efficiency were observed when all the three components were coated with the proprietary TBC. Two hypothetical TBC materials with ideally low thermal effusivities were formed by modifying the current material properties and their effect on engine performance was similarly studied at three engine loads at the same engine speed. It was found that coating all the three components with the lowest thermal effusivity TBC offers the largest improvements (∼0.5% points) in net fuel conversion efficiency accompanied by largest reduction (∼1.1% points) in total heat transfer, thus establishing expectations from future TBC materials.