Long life elastocaloric regenerator operating under compression

Abstract

Elastocaloric cooling represents a potentially higher efficiency cooling technique that is also potentially more environmentally friendly than conventional technologies. Elastocaloric devices have now been investigated for some time for this purpose, with materials that are Cu-based, Fe-based or Ni-based. These devices are highly promising, but their main drawback is the lifetime of the devices. A solution could be to activate the devices by compression instead of tension. An active elastocaloric regenerator operating under compression composed of eight NiTi tubes was built and tested in a flow system to evaluate its performance and lifetime. Two regenerator configurations were tested, one with only the NiTi tubes in the regenerator and one with the addition of a flow distributor to improve the thermal exchange between the tubes and the heat transfer fluid. The flow system used was also optimized and modified to reach the best operating conditions. A maximum temperature span of 5 K could be reached by this regenerator and a temperature span of 0.4 K for a cooling power of 1071 W kg−1. Moreover, under compressive cycling, the regenerator could withstand more than 100 000 cycles without failure.