MEMS-based resonant heat engine: scaling analysis

In this article, a scaling model of a MEMS-based resonant heat engine is presented. The engine is an external combustion engine made of a cavity encapsulated between two thin membranes. The cavity is filled with a saturated liquid–vapor mixture working fluid. Both model and experiment are used to investigate issues related to scaling of the engine. The results of the scaling analysis suggest that the performance of the engine is determined by three major factors: geometry of the engine, speed of operation, and thermal-physical properties of engine components. Larger engine volumes, working fluids with higher latent evaporation property, slower engine speeds, and compliant expander structure are desirable. In experiments, the expander membrane material and thickness, and the thickness of engine cavity are varied. The experimental measurements show that the velocity amplitude of the expander membrane increases by approximately a factor of 20 when more compliant structure with less thermal inertia is used.