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The reduction of the heat loss from the in-cylinder gas to the combustion chamber wall is one of the key technologies for improving the thermal efficiency of internal combustion engines. This paper describes an experimental verification of the “temperature swing” insulation concept, whereby the surface temperature of the combustion chamber wall follows that of the transient gas. First, we focus on the development of “temperature swing” insulation materials and structures with the thermo-physical properties of low thermal conductivity and low volumetric heat capacity. Heat flux measurements for the developed insulation coating show that a new insulation material formed from silica-reinforced porous anodized aluminum (SiRPA) offers both heat-rejecting properties and reliability in an internal combustion engine. Furthermore, a laser-induced phosphorescence technique was used to verify the temporal changes in the surface temperature of the developed insulation coating.

To improve fuel efficiency of engines, cooling heat loss is one of the most dominant losses among the various engine losses to reduce. The present work proposes a new heat insulation concept in combustion chamber, "TSWIN (Thermo-Swing Wall Insulation Technology)" that can reduce heat loss to the coolant without any sacrifice in other engine performances. Surface temperature of insulation coat on combustion chamber wall changes rapidly, according with the fluctuating temperature of in-cylinder gas. Reduced temperature differences between them lead to lower heat transfer. During the intake stroke, surface temperature of the insulation coat goes down rapidly, and prevents intake air heating. To realize the scheme mentioned above, a new insulation material with both low thermal conductivity and low volumetric heat capacity, "SiRPA (Silica Reinforced Porous Anodized Aluminum)" was developed and applied on the top surface of the piston.