Numerical Analysis on the Exploitation of Niti-Based Shape Memory Alloys in an Elastocaloric Device for Air Conditioning

Elastocaloric is a promising cooling technique that offers a solid-state alternative to vapor compression. The elastoCaloric Effect (eCE) refers to the reversible changes in temperature and entropy that occur in Shape Memory Alloy (SMA) when loaded/unloaded by an external mechanical load. The research introduced in this paper compares vari-ous Ni–Ti-based SMAs to determine the optimal one to be exploited in an experimental air conditioner. The device can lodge 600 SMA wires in the space stacked by two cylin-ders concentrically arranged, with inner/outer diameter of 250/280mm. Tests are performed while the device rotates at variable frequencies ranging from 0.3Hz to 0.7Hz. A rotary meshing two-dimensional tool has been developed and used to perform the test campaign under variable working condi-tions and NiTi-based SMAs. The energy performances are evaluated and (Ni50Mn31.5Ti18.5)99.8B0.2 resulted in the most suitable SMA showing 2.13kW as peak of cooling power (at a cycle frequency of 0.6Hz and a utilization factor of 0.7) and a maximum COP of 8.35 (at 0.3Hz and 0.7 as utilization factor). This work demonstrates that the use of the (Ni50Mn31.5Ti18.5)99.8B0.2 alloy can enable the device to achieve performances superior to vapor compression-based devices.