A heat driven elastocaloric cooling system

Abstract Elastocaloric cooling is based on the latent heat associated with phase transformation upon stress variations in shape memory materials, which has significant potential to reduce the environmental footprints for air-conditioning and refrigeration industry. However, current elastocaloric cooling prototypes are limited by their driver to refrigerant mass ratio of over 500. To overcome this bottleneck, a new cycle using high temperature shape memory alloy as the heat driven actuator is proposed, which can precisely match the force-displacement characteristics of the refrigerant super-elastic alloy, and thus could potentially reduce the driver to refrigerant mass ratio down to the magnitude of 1. Numerical simulations are carried out to study the transient characteristics of the new cycle and the impacts of the heat source temperature and transformation temperatures of the actuator alloy. These two groups of parameters are correlated as the thermodynamic driving temperature differences. Furthermore, the theoretical minimum driving temperature shows that a low grade heat source around 80 °C is sufficient, which opens a new path for better utilization of the renewable energy and the waste heat. In the end, the design of a demonstrator based on the proposed cycle is presented, which shows a new path to develop compact elastocaloric cooling prototypes.