화학공학소재연구정보센터
Applied Energy, Vol.162, 1439-1452, 2016
Polyols as phase change materials for surplus thermal energy storage
Storing low-temperature surplus thermal energy from industries, power plants, and the like, using phase change materials (PCM) is an effective alternative in alleviating the use of fossil based thermal energy provision. Polyols; of some also known as sugar alcohols, are an emerging PCM category for thermal energy storage (TES). A review on polyols as PCM for TES shows that polyols have phase change temperatures in the range of 15 to 245 degrees C, and considerable phase change enthalpies of 100-413 kJ/kg. However, the knowledge on the thermo-physical properties of polyols as desirable PCM for TES design is presently sparse and rather inconsistent. Moreover, the phase change and state change behaviors of polyols need to be better-understood in order to use these as PCM; e.g. the state change glass transition which many polyols at pure state are found to undergo. In this work preliminary material property characterization with the use of Temperature-History method of some selected polyols, Erythritol, Xylitol and Polyethylene glycol (PEG) 10,000 were done. Complex behaviors were observed for some of the polyols. These are: two different melting temperatures, 118.5-120 degrees C and 106-108 degrees C at different cycles and an average subcooling 18.5 degrees C of for Erythritol, probable glass-transition between 0 and 113 degrees C for Xylitol, as well as a thermally activated change that is likely an oxidation, after three to five heating/cooling cycles for Xylitol and Erythritol. PEG 10,000 had negligible subcooling, no glass-transition nor thermally activated oxidation. However a hysteresis of around 10 degrees C was observed for PEG 10,000. Therefore these materials require detailed studies to further evaluate their PCM-suitability. This study is expected to be an initiation of an upcoming extensive polyol-blends phase equilibrium evaluation. (C) 2015 Elsevier Ltd. All rights reserved.