A Concept Review of Low-Heat-Rejection Engines

Insulated engines have become popular ideas with the development of new materials and material processing techniques. Several research groups have been involved and are producing needed, quality information about low-heat-rejection engines. To date, a comprehensive review has not been presented, like the work included here, that identifies and discusses the various programs and results, or even the breadth of the different topics being undertaken. This paper presents a comprehensive literature review of low-heat-rejection engine concepts and brief discussions of some modeling techniques, both heat transfer models and engine models, being used to further the knowledge base in this field. The general, established concepts and history of low-heat-rejection engines are briefly covered before each individual area of interest is presented. These are temperatures of low-heat-rejection engines, new material requirements, new construction techniques to facilitate the new materials, tribology, emissions, noise concerns, new fuel capabilities, and exhaust heat utilization. The importance of a “whole system” approach is stressed. Inconsistencies in the literature are also discussed.