Novel microstructured polyol-polystyrene composites for seasonal heat storage
journal contributionposted on 19.02.2018, 14:26 by Salla Puupponen, Valtteri Mikkola, Tapio Ala-Nissila, Ari Seppala
© 2016 Elsevier Ltd.We propose a robust route to prepare novel supercooling microstructured phase change materials (PCMs) suitable for seasonal thermal energy storage (STES) or heat protection applications. Two supercooling polyols, erythritol and xylitol, are successfully prepared as novel microencapsulated PCM-polystyrene composites with polyol mass fractions of 62 wt% and 67 wt%, respectively, and average void diameter of ~50 μm. Thermal properties of the composites and bulk polyols are studied thoroughly with differential scanning calorimetry (DSC) and thermal conductivity analyzer. Significant differences in heat storage properties of microstructured and bulk PCM are observed. The heat release of microstructured erythritol is more controlled than that of bulk PCM, making the novel microengineered PCMs particularly interesting for STES. In the case of bulk PCM, the heat release may occur spontaneously due to crystallization by surface roughnesses or impurities, whereas these factors have only little impact on the crystallization of microstructured erythritol, making the novel composite more reliable for long-term heat storage purposes. In addition, microstructured polyol-polystyrene composites show anomalous enhancement in the specific heat as compared to bulk polyols. This enhancement may originate from strong polyol-surfactant interactions in the composites.
The research was funded by the Fortum Foundation, the Aalto Energy Efficiency Research Programme (EXPECTS-project) and the Academy of Finland through its COMP CoE Grants 251748 and 284621 (T. A-N.). This work was also supported by the Efficient Energy Use (EFEU) research program coordinated by CLEEN Ltd. with funding from the Finnish Funding Agency for Technology and Innovation, Tekes.
- Mathematical Sciences