MISTIC - Micro Stirling Heat Engines for Thermal Energy Harvesting

This paper reports on the fabrication and validation of the piston assembly for a new micro heat engine based on the Stirling cycle, (MISTIC - MIcro STIrling Clusters), intended for electric power generation by harvesting low temperature waste heat (≥ 200° C). Here, we define the requirements, develop the fabrication processes and fabricate piston assemblies to show the feasibility. Static and dynamic response of the pistons show that high quality factors (Q>100) are achievable with the polymer structures and the natural frequencies of adjacent pistons can be matched (within 4 percent), two characteristics required to allow start-up of the engine. We also demonstrate an electromagnetic actuator that is capable of individually exciting the pistons to further facilitate start-up. (paper)