RT100/expand graphite composite phase change material with excellent structure stability, photo-thermal performance and good thermal reliability

The combination of a phase change material (PCM) with expanded graphite (EG) is a simple and effective way to obtain a form-stable composite PCM with relatively high latent heat and enhanced thermal conductivity. In this paper, aiming at developing a high-performance PCM for medium-temperature latent heat storage applications, RT100, a mixture of paraffinic hydrocarbons with a melting point of around 100 °C, has been selected as the PCM to prepare a novel EG-based composite. It is shown that the RT100/EG composite containing 80 wt% RT100 is a form-stable PCM. The form-stable RT100/EG composite PCM powders can be compressed into round blocks by dry pressing. All the RT100/EG composite PCM round blocks have much higher thermal conductivity than RT100, and their thermal conductivity linearly increases with the packing density. The thermal conductivity of composite PCM round blocks maintain even in the melting process. Further, the RT100/EG composite PCM shows excellent photo-thermal and direct thermal storage/release performance in simulative condition. Finally, the 200 heating-cooling cycles test along with the structure and thermal property characterizations indicates that the RT100/EG composite PCM has excellent structure stability and good thermal reliability. As a result, the RT100/EG composite PCM with excellent structure stability, good thermal reliability, good formability, enhanced thermal conductivity, excellent photo-thermal performance and good thermal storage/release capacity shows great potential for use in medium-temperature thermal energy storage applications.