Preparation of castable phase change materials beads based on millimeter-sized nanocarbon aerogels for thermal energy storage

Abstract

Nanocarbon-based porous materials such as graphene foams and aerogels can improve the thermal conductivity and shape stability of phase change materials (PCMs) obviously and simultaneously. However, it is still inconvenient to use these nanocarbon-based composite PCMs in practical applications and engineering, and rare research attention has been paid to this problem. Here we report that making PCMs and nanocarbon aerogels into millimeter-sized PCM beads can be a promising solution of this problem. The nanocarbon aerogels were prepared from carbon nanotubes and graphene oxide, and had a thermal conductivity of 93 mW/mK. PCM beads had improved thermal conductivity and shape stability. The phase transition enthalpy of paraffin-based PCM beads reached 187–188 J·g−1. PCMs beads could be casted with a variety of matrix materials to create large-sized composites with designed size and shape. This castability makes PCM beads compatible with many current techniques and materials, such as concrete pouring techniques and decoration materials, that have already been used in practical applications and engineering. The heat conduction in PCM beads/paraffin casted composites was found to be 25 times faster than that in neat paraffin. PCM beads/concrete casted composites had the potential to be used in building temperature regulation. Overall, our work has demonstrated a new kind of nanocarbon-based composite PCMs with an integration of high properties and high convenience for practical applications and engineering.