The energy performances of an elastocaloric device for air conditioning through numerical investigation

The urgent needing to address global warming and the rapid depletion of fossil fuel reserves has led to a demand for immediate research in sustainable and clean energy technologies. Elastocaloric cooling is a promising proposal for clean refrigeration because of the zero global warming potential of the shape memory alloys, which are solid-state materials showing elastocaloric effect. The latter manifests when the shape memory alloys are stressed through a mechanical loading, transforming from the austenite phase toward the martensite one and releasing heat, dually transforming from the martensite phase into the austenite phase and absorbing heat. The updated literature accounts for 15 elastocaloric cooling devices, but none is close to commercialization. The efforts are devoted to making this decisive step by implementing new efficient devices. This paper analyses the energy performances of an elastocaloric rotary prototype employing binary NiTi wires through the first rotary bidimensional numerical model based on the finite element method to attain the device's potential cooling and heating capacities. In this paper, the energy performances of an elastocaloric rotary prototype employing binary NiTi wires are analyzed through a 2D numerical model based on the finite element method to attain the device's potential cooling and heating capacities. The model reproduces the thermo-fluid-dynamic behaviour of an experimental rotary device for air conditioning; meanwhile, the secondary fluid in the device is air. The accuracy of the rotary model easily allows to optimize the operating parameters of the elastocaloric prototype under construction. Results in terms of outlet air temperature, cooling power and coefficient of performance are presented for different air velocities inside the air channel and different rotation frequencies of the device. A performance map has been obtained by exploring the device's behaviour in the cooling mode under variable working conditions to identify the optimal configuration. A maximum COP of 6.22 (corresponding to a second law analysis efficiency of 60%) was evaluated under an airflow speed of 6 m s−1 and a frequency of 0.3 Hz, corresponding to . 28.5 K and 5400 W kg−1 are the reached peaks of temperature span and cooling power.