Thermal properties of shape-stabilized phase change materials based on porous supports for thermal energy storage

The use of phase change materials (PCM) for thermal energy storage (TES) is of great relevance, especially for the exploitation, in various ways, of the major ecological resource offered by solar energy. Unfortunately, the transition to the liquid state of PCM requires complex systems and limits their application. The goal of producing shape-stabilized phase change materials (SSPCM) is mainly pursued with the use of media capable of containing PCM during solid/liquid cycles. In this work, four cheap shape stabilizers were considered: sepiolite, diatomite, palygorskite and zeolite and two molten salts as PCM, for medium (MT) and high temperature (HT). The SSPCM, produced with an energy saving method, showed good stability and thermal storage performances. Diatomite reaches up to 400% wt. of encapsulated PCM, with a shape stabilization coefficient (SSc) of 97.7%. Zeolite exhibits a SSc of 87.3% with 348% wt. of HT-PCM. Sepiolite contains 330% wt. of MT-PCM with an SSc of 82.7. Therefore, these materials show characteristics such that they can be efficiently used in thermal energy storage systems, both individually and inserted in a suitable matrix (for example a cementitious matrix).