Continuous operating elastocaloric cooling device: First experimental results

Superelastic NiTi enables a novel environment-friendly cooling technology without global warming potential. Elastocaloric cooling uses solid stateNiTi shape memory alloys (SMA’s) as a non-volatilecooling medium compared to vapor compression-based cooling systems. In addition to being used in lightweight actuator systems and biomedical applications, these alloys exhibit excellent cooling properties. Due to the high latent heats activated by mechanical loading/unloading, large temperature changes can be generatedin the material. Accompanied by a small required work input, a high coefficient of performance is achieved. The potential of these alloys can be accessedby the use of a suitable thermodynamic cooling cycleand efficientsystem design.

This contribution presents the realization of the novel continuous operating elastocaloric cooling device. The device is dividedintotwo parts, a heat transfer system designed for fluid cooling and a mechanical system for individual loading and unloading of multiple SMA wire bundles. The transfer system enables an efficient heat exchange between heatsource and SMA as well as between SMA and environment. The device operates without any additional heat transfer medium and cools the heat source directly, which is an advantage in comparison to conventional cooling systems. The loading unit enables an arbitrary elastocaloric process control. Supporting the design process of the device a system level simulation tool is developed which is capable of predictingthe system parameters at various operatingconditions. The first elastocaloric cooling system for air as gaseous fluid is realized. First experiments are presented and compared to simulation.