Enhanced properties of stone coal-based composite phase change materials for thermal energy storage

Phase change material (PCM) can be incorporated with low-cost minerals to synthesis composite for thermal energy storage in building applications. Stone coal after vanadium extraction treatment shows potential in secondary utilization of composite preparation. This work prepared the stone coal-based composite PCM that stone coal as matrix, stearic acid as PCM, and expanded graphite as additive. To understand the effect of vanadium extraction on promotion of loading capacity and thermal conductivity, the analogous treatment of roasting and acid leaching on raw stone coal was conducted. Results show that the combined treatment of roasting at 900°C and leaching increases the loadage of stone coal in composite by 6.2% due to the improvement of specific surface area. Being contributed by 3% expanded graphite, both loading capacity and thermal conductivity of composite are obviously increased by 127% and 48.19%, respectively. Data is supported by the designed composite which has high loadage of 66.69% and thermal conductivity of 0.59 W m^-1 K^-1. The obtained composite exhibits phase change temperature of 52.17°C and melting latent heat of 121.5 J g^-1, as well as good chemical compatibility. The stone coal-based composite has prospects in building applications by taking advantage of secondary utilization of minerals.