MELTING HEAT TRANSFER CHARACTERISTIC OF ENCAPSULATED COMPOSITE PHASE CHANGE MATERIAL

To improve the heat storage rate of latent heat energy storage materials, the paper studied numerically the dimensionless melting heat transfer process of encapsulated composite phase change material (PCM) with the first class boundary condition. It also explored the temperature distribution in capsule, the moving trail of the phase interface position and the complete melting time of the capsule. The mathematical model was solved by effective heat capacity method. Several important factors were available, including Stefan numbers, phase change temperature radius and the thermal performance of the capsule materials. The results show that the more the Stefan numbers, the more dramatic the difference between the liquid and the solid phase interface; the impact of the phase change temperature radius on the temperature distribution inside the capsule is greater than near the capsule wall; when the thermal conductivity of the capsule wall materials is quite high, it is no effective to improve the heat transfer rate by increasing the thermal conductivity or reducing the thickness of the capsule wall. The above results would have practical guidance significance to how to improve heat storage capacity and heat storage rate of the PCM in buildings.