High Pressure Solvothermal Microencapsulation of D-Mannitol in Inorganic Shells for Thermal Energy Storage

D-Mannitol has been demonstrated by different authors as a new phase change material (PCM) for thermal energy storage with high latent heat, low cost, environmentally friendly chemical nature and suitable melting temperature for applications in solar collectors, space heating or industrial waste heat. The main drawback is their low thermal conductivity, affecting heat transfer properties. In this work, the microencapsulation of D-Mannitol in ZnO shells is evaluated as a procedure to increase the specific area of heat exchange. The inorganic shell based on ZnO has been selected for the microencapsulation using an in-situ solvothermal followed by spray drying. Characterization of the microcapsules obtained has been mainly carried out by XRD, DSC, IR spectroscopy and SEM. Results have shown that experimental parameters such as the pressure and reaction time for the solvothermal microencapsulation process determine the crystalline phases of the shell and their thermal energy storage properties (melting temperature and enthalpy).