International Journal of Energy Research, Vol.44, No.1, 425-437, 2020
Thermal performance investigation of a single medium temperature phase change microcapsule used for wind power absorption and heat storage system
Phase change microcapsules have a wide application in the heat storage system. The medium temperature heat storage systems such as medium temperature solar thermal plants, waste heat recovery systems and wind power absorption systems. In order to analyse the effects of configuration parameters and materials on phase change heat transfer process in a single medium temperature microcapsule, an enthalpy-transforming model was applied to trace the location of the solid-liquid interface and obtain the liquid fraction at different time in the melting process. Based on this model, the effects of particle size, the effects of wall thickness, the effects of wall materials and different medium temperature phase change materials were analyzed. The numerical results show that the larger particle size has a longer melting time, the melting time of 50 mu m particle size and 250 mu m particle size is 0.036 s and 2.48 s, respectively. In addition, the melting time of microcapsules with different wall thicknesses from the 1 mu m to 9 mu m is the same i.e., 0.14 s. Therefore, the wall thickness has little effect on the melting time of microcapsules. Besides, the microcapsule with the erythritol as inner material and the polystyrene as wall material has the longest melting time. Furthermore, the thermal conductivity of the wall materials is the main factor affecting the melting time. Moreover, the product of latent heat and density of phase change material is the main factor of the melting time.