The present work explores the feasibility of using polyalcohols with solid-solid phase transition as active supporting matrix of n-alkanes in shape-stabilized phase change materials (SSPCMs). It is well-established that the use of SSPCM avoids leakage and increases stability and easy handling of solid-liquid PCMs. Nevertheless, the resulting composite exhibits a loss of heat storage capacity due to the volume occupied by the supporting material, which does not contribute to latent heat storage. Therefore, the objective of this work is to combine solid-liquid PCMs (alkanes) with solid-solid PCMs (polyalcohols), both exhibiting a phase transition in the same range of temperature, to obtain high energy density SSPCMs. Towards that goal, the performance of Neopentyl Glycol (NPG) and Docosane as a new energetic SSPCM has been proved. The NPG-Docosane chemical compatibility and its outstanding wettability facilitate the propitious association of both materials. The higher capillary forces obtained by decreasing the NPG crystal size together with the addition of expanded graphite (EG) allowed to obtain a maximum Docosane content of 60 wt%. The addition of EG improves the shape stability at the time that increases the heat transfer properties of the composites. The analysis showed that the components of the obtained SSPCMs are able to combine their latent heats, achieving a maximum value of 210.74 J/g for the highest Docosane content. This value is much higher than those latent heats exhibited by existing SSPCMs in the same working temperature range.
Keywords: Docosane; Neopentyl Glycol; expanded graphite; shape-stabilized phase change material; solid-solid PCM; thermal energy storage.