Material issues for a regenerator designed for internal combustion engines.

摘要

Adaptation of new material technologies and testing methods of internal combustion engines, which lead to superior products while simultaneously reducing both, cost and damage to the environment is the primary aspiration behind this project.; To improve the thermal efficiency of internal combustion engines, regeneration of the thermal energy should be utilized. In recent years, new theoretical proposals for internal thermal regenerations of diesel engines have been promising significant operational advantages. One such regeneration technology is proposed by Rejen to dramatically improve the efficiency of diesel engines. However, to realize the proposed benefits, a structurally reliable internal regenerator must be designed and tested. This project encompasses many objectives. The first objective is to select and procure a suitable material for the thermal regenerator. The second objective is to build a simplified mock up engine assembly to simulate the mechanical loads that the regenerator will undergo. The third objective is to test the regenerator material for mechanical fatigue and inertial loads.; For successful material selection of the regenerator material, determination of the material properties is crucial to a successful design. Since it is now possible to design ceramic materials in various forms of cellular architecture, SiC foam is selected as the core regenerator material. Because of the lack of any substantial information about the mechanical properties of SiC foam, a significant effort is necessary to establish the basic reaction of the foam material to the mechanical loads. Therefore, in this work, the results of testing the mechanical properties of SiC foams are reported. The testing done in this project includes static and dynamic testing.; In addition, rapid reciprocation of the engine is associated with inertial body forces that would limit the maximum regenerator RPM. Therefore, the effects of the inertial loading on the stability and the integrity of the regenerator foam is studied to ensure the success of the regenerator in the engine. To conduct the inertial testing, sample SiC foam regenerators were mounted on a custom engine assembly designed specifically for this experiment. The engine consists of the block of 1953 Ford Flathead engine driven by a 7.5 HP electric motor. The variation in inertial loading on the regenerator is accomplished by adding progressive weights to the top of the regenerator. Furthermore, theoretical Finite Element Analysis is performed and the results of the maximum stress at failure were compared to the experimental results. The experimental work done in this part of the project led to the conclusion that the resistance of the foam to inertial loading is mainly correlated to the linear pore density of the foam material. Finally, our test results indicate that inertial load induced failure of the SiC regenerators is unlikely if the foam selected is 30% density and 130--160 pores per inch. Therefore, we could conclude that such particular SiC foam could survive indefinitely without thermal stress effects.