Reducing diesel engine heat rejection by the selected application of insulating ceramics is an approach that has been investigated to improve the diesel engine's fuel economy, increase engine power density, and reduce parasitic losses (1-3). Through refined engine cycle simulation models it has been projected that the direct fuel economy benefits are approximately 1.5% at a 40% reduction of in-cylinder heat rejection for specific turbocharged engines and approximately 3% at the equivalent heat reduction for a turbocompound version of the same engine (1). Indirect benefits for these engines through the reduction of parasitic losses, smaller water pumps, fans, and other componentry as well as the potential for improved vehicle aerodynamics have not been quantified.

To achieve the 40% reduction in in-cylinder heat rejection, either a relatively thick (approximately 2 mm to 2.5 mm) thermal barrier coating is required or an even greater thickness of sintered zirconia ceramics because of their higher thermal conductivities.

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