Thermal reliability of organic-organic phase change materials and their shape-stabilized composites

Abstract

Thermal reliability is one of the main concerns when using shape-stabilized phase change materials (SS-PCMs) composites in latent heat thermal energy storage (TES) systems operating in moderate to low temperature range. Thus, this paper presents a study of the thermal stability, chemical stability, and thermal properties of three binary eutectic mixtures of fatty acids: capric/myristic acid (CA/MA), lauric/myristic acid (LA/MA), and palmitic/stearic acid (PA/SA); as well of three SS-PCMs produced with a natural porous support: SS-CA/MA, SS-LA/MA and SS-PA/SA. The eutectics and the SS-PCMs were exposed to several heating/cooling cycles and then infrared spectroscopy was carried out to determine chemical changes. Moreover, phase change temperature, latent heat of fusion, and latent heat of solidification were measured by differential scanning calorimetry. The eutectics and composites were proven to present good thermal reliability over 100 cycles for CA/MA and SS-CA/MA, and up to 10000 cycles for LA/MA, PA/SA, SS-LA/MA and SS-PA/SA. The melting temperatures for the composites were between 19.5°C and 53.2°C, and enthalpies between 38 J/g and 49 J/g, with maximum deviation after thermal cycling below 2.03°C and 11.45 J/g. These results confirm that these materials have significant potential to be used for thermal energy storage applications that required good thermal reliability.