Microencapsulation of phase change materials for thermal energy storage at low temperatures

In this study, microcapsules of phase change materials (PCMs) were prepared for thermal energy storage. In the preparation of encapsulated PCMs, coacervation technique was used. Paraffin and coco fatty acid mixtures were used as core materials of capsules. Microcapsules of paraffin were prepared from four different wall materials, including urea-formaldehyde resin, melamin formaldehyde resin, p naftol formaldehyde resin and gelatin-gum arabic coacervate. In the microencapsulation process of coco fatty acid mixtures gelatin-gum arabic were used as the wall material. Hardening process of encapsulated PCMs was done with formaldehyde. The distribution of particle size and the geometric profile of microencapsulated PCM were analyzed by optic microscope. Microcapsules, prepared by coacervation process has spherical geometric profile. Based on stirring speed or stirring time capsul diameters can vary from 1 urn to 1 mm. Phase transition temperature and suitability for thermal energy storage of the PCMs were determined by melting and freezing curves which were obtained from constant temperature water bath and air chamber. The latent heat storage capacities of parafin and microencapsulated parafin were determined by the temperature-history method, proposed by Yinping. It is concluded that gelatin - gum Arabic was the best capsule wall material for paraffin and coco fatty acid mixtures.Keywords: Microcapsule, Encapsulation, Phase Change Material (PCM), Coacervation, Thermal Energy Storage II