Design and Evaluation of a MEMS-Based Stirling Microcooler

1 Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA 15213-3890 2 Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA 15213-3890 3 Isotherm Technologies LLC, Medina, OH, USA 44256-6431 ABSTRACT A new Stirling micro-refrigeration system composed of arrays of silicon MEMS cooling elements has been designed and evaluated. The cooling elements are to be fabricated in a stacked array on a silicon wafer. A regenerator is placed between the compression (hot side) and expansion (cold side) diaphragms, which are driven electrostatically. Air at a pressure of 2 bar is the working fluid and is sealed in the system. Under operating conditions, the hot and cold diaphragms oscillate sinusoidally and out of phase such that heat is extracted to the expansion space and released from the compression space. Parametric study of the design shows the effects of phase lag between the hot space and cold space, swept volume ratio between the hot space and cold space, and dead volume ratio on the cooling power. Losses due to regenerator non-idealities are estimated and the effects of the operating frequency and the regenerator porosity on the cooler performance are explored. The optimal porosity for the best system COP is identified.