In order to reduce the amount of energy consumption, the need for enhancement of energy efficiency has been raised. The phase change materials (PCMs), which can store and release the latent heat, have come into the spotlight as one of the solutions. In order to apply the PCMs to industry, some methods for encapsulating the PCM with diameter of ca. 2-50 µm using metallic and polymeric shell had been researched. However, metal is corrodible in aqueous fluid, and polymer has low thermal conductivity. Furthermore, previously researched PCM capsules have a limitation of low thermal storage capability due to the low core content by their small size.<br/>In this study, to overcome the shortcomings, we have manufactured PCM capsules with diameter of ca. 400 µm, encapsulated with water-absorbable polymer. Paraffin and poly(2-hydroxyethyl methacrylate) (pHEMA) were used as a PCM and a shell, respectively. The pHEMA can reduce the problem of low thermal conductivity of polymer because pHEMA can show high thermal conductivity by water-absorbing property. The thermal conductivity of hydrous pHEMA, measured by LFA, was 0.47 W/m K which is far higher than the researched polymeric shell. The PCM@pHEMA showed great endurance during repetitive phase change processes due to the elasticity and flexibility of hydrous pHEMA. The thermal storage capability of PCM@pHEMA, calculated by the latent heat capacity measured by DSC, was 99.65%, which is higher than previously studied PCM capsules owing to its high core content by enlargement of capsule size.<br/>Our study demonstrates that the hydrous polymer is an effective shell material of PCM for thermal storage. In addition to the use of the manufactured capsules as carrier of thermal energy, the capsules can become an attractive material for various temperature sensitive fields of industry, such as outdoor wear, buildings, houses, and refrigerator vehicles by storage and release thermal energy.

Water-absorbable, polymer-coated phase change material for thermal energy storage

251st National Meeting (2016)

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