Low-Force Elastocaloric Regenerators and Systems

Elastocaloric cooling is a leading candidate for next-generation thermal technologies that can meet the demands of residential, commercial, and industrial applications. Its potential for higher efficiency and improved reliability compared to vapor compression systems has been demonstrated in initial prototypes. Our research focuses on developing low-force, high-efficiency elastocaloric devices using commercially available Nitinol. The thin-sheet form, with its high surface-area-to-volume ratio, enables efficient heat transfer and rapid thermal response when operated in tension with a water-based heat transfer fluid. Based on previous work that demonstrated bending of a composite structure to apply tensile stresses to Nitinol, we have extended that concept to multiple plates and a balanced structure. A system consisting of multiple active regenerators was developed to demonstrate scalability. We present the design and experimental performance of active regenerators, including a system featuring energy recovery and multiple regenerators. Longevity tests on an active regenerator and cyclic fatigue testing of materials under representative operating conditions are used to evaluate expected system lifetime and material durability.

This work was supported by the U.S. Department of Energy (DOE) and the U.S. Department of Defense. The research was performed at Ames National Laboratory, which is operated for the U.S. DOE by Iowa State University under contract # DE-AC02-07CH11358.