Continuous operating elastocaloric cooling device: First modeling results

Superelastic NiTi enables a novel environment-friendly cooling technology without global warming potential. Elastocaloric cooling uses solid state NiTi shape memory alloys (SMA’s) as a non-volatile cooling 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 high latent heats activated by mechanical loading/unloading, large temperature changes can be generated in the material. Accompanied by small required work input, a high coefficient of performance is achieved. The potential of these alloys can be accessed by use of a suitable thermodynamic cooling cycle and efficient system design.

This contribution presents the system level model of the realized novel continuous operating elastocaloric cooling device. The model covers the two parts of the device, heat transfer system designed for fluid cooling and mechanical part with individual loading and unloading of multiple SMA wire bundles which represent the thermo-mechanical coupling. The heat transfer system enables efficient heat exchange between heat source and SMA, as well as between SMA and environment. The loading unit enables an arbitrary elastocaloric process control. Supporting the design process of the device a system-level simulation and animated visualization tool combine with parallel computing option is developed which is capable of predicting the system parameters at various operating conditions, to guide the economic development of an efficient cooling device. The first elastocaloric cooling system for air as gaseous fluid is realized. First model-based parameter studies of the working machine are presented and discussed.