Phase-change Material - Thermal Composites

Thermal Composites

Thermal-composites is a term given to combinations of phase change materials (PCMs) and other (usually solid) structures. A simple example is a copper-mesh immersed in a paraffin-wax. The copper-mesh within parraffin-wax can be considered a composite material, dubbed a thermal-composite. Such hybrid materials are created to achieve specific overall or bulk properties.

Thermal conductivity is a common property which is targeted for maximisation by creating thermal composites. In this case the basic idea is to increase thermal conductivity by adding a highly conducting solid (such as the copper-mesh) into the relatively low conducting PCM thus increasing overall or bulk (thermal) conductivity. If the PCM is required to flow, the solid must be porous, such as a mesh.

Solid composites such as fibre-glass or kevlar-pre-preg for the aerospace industry usually refer to a fibre (the kevlar or the glass) and a matrix (the glue which solidifies to hold fibres and provide compressive strength). A thermal composite is not so clearly defined, but could similarly refer to a matrix (solid) and the PCM which is of course usually liquid and/or solid depending on conditions.