Latent thermal energy storage using solid-state phase transformation in caloric materials

Abstract

Materials with solid-to-solid phase transformations have considerable potential for use in thermal energy storage systems. While these materials generally have lower latent heat than materials with a solid-to-liquid phase transformation, their significantly higher thermal conductivity enables rapid thermal charging/discharging. Here, we show that this property makes them particularly promising for thermal energy storage applications requiring highly dynamic operation. A numerical analysis (using an experimentally validated numerical model) has revealed that some materials with solid-to-solid phase transformations offer an excellent capacity-power trade-off for thermal energy storage applications compared to the corresponding conventional phase change materials. While most conventional phase change materials generally offer higher thermal capacity due to larger latent heat, some metallic materials with solid-state transformation (e.g., Ni-Ti-based alloys, Mn-Co-Ga-B alloys) exhibit up to 10 times higher thermal output powers. These results highlight a significant potential of caloric solid-state materials to outperform traditional latent thermal storage systems for certain applications.