Experimental study on heat storage and exothermic characteristics of spherical high temperature fixed composite phase change materials

Abstract

ABSTRACT In this study, Al-Si/fly ash spherical high temperature shaped composite phase change material (heat storage ball) was made, and an experimental device for heat storage and release characteristics of the heat storage ball was designed and built. The experiment verified that the accuracy of the device met the requirements. The surface and center temperature of four heat storage spheres with different heating/cooling rates and different pressing processes were measured and their heat storage and release characteristics were analyzed. The results show that the heating/cooling rate is higher, the heat storage/release rate is higher, the temperature difference between the surface layer and the center of the heat storage sphere is greater, the heat transfer resistance is greater, and the heat storage/release efficiency is lower. The heating/cooling rate and the diameter of the regenerative ball had little influence on the temperature at the melting/solidification starting point, but had great influence on the temperature at the melting/solidification ending point of the regenerative ball. The phase transition temperature range of Al-Si alloy was expanded, the heating rate was higher, the melting termination point temperature was higher. Higher grade heat energy was needed for heating and heat storage, it increased the requirement of heat source. The end temperature of solidification of cooling rate 6°C/min and 9°C/min was lower than 500°C, it exceeded the lower limit of high-temperature heat storage/exothermic temperature, and the utilization of high-temperature heat energy could not be realized. For high-temperature heat storage/release, the 15 diameter heat storage ball was prepared by the process (1), phase change latent heat was high and heat storage was ample. When the heating/cooling rate was 3°C/min, the phase change temperature range of Al-Si alloy was relatively reasonable, the heat storage phase change temperature was 567.0 ~ 599.9°C, and the exothermic phase change temperature was 542.4 ~ 504.7°C, it met the requirements of high-temperature heat storage/release.