Thermal, Mechanical, and Materials Aspects of a Shape Memory Alloy Stirling Heat Engine

This work analyzes a shape memory alloy Stirling heat engine through an integrated thermal, mechanical, and materials approach. It builds on our previously published framework by generalizing behavior of shape memory alloys (SMA) beyond the nanoscale and extends it to elastocaloric applications, where mechanical work can be used to induce the stress-induced phase transformation. Parallels between stress-strain and enthalpy-temperature behavior underline this extension. Heat engine performance is evaluated in terms of torque and speed, and consideration is given to fatigue service life. Heat transfer and transformation energetics are examined with implications for heat engine performance. The resulting work supports shape memory alloy based heat engines and refrigerators for thermal management in space applications.