STUDY ON THE CHARACTERISTICS OF CASCADE HEAT STORAGE BASED ON SERIES COMPOSITE PHASE CHANGE MATERIALS

For the problem of enhancing the thermal performance of heat storage device, the phase change process of the two-stage series heat storage device based on composite phase change material (PCM) was studied by simulation and experiment. The heat storage time was obtained by changing the inclination angle of the partition plate between the two PCMs. The effect of natural convection on melting process of PCMs was analyzed through the evolution of the phase interface. The results show that the leftward-tilting partition makes heat storage time long despite of the heat flux. The rightward-tilting partition can significantly promote the overall melting process under even a small heat flux, while it does not reduce heat storage time obviously under a large heat flux. Finally, by introducing dimensionless parameters, general ways to enhance the performance of a two-stage series heat storage device were summarized.