Research On Heat Storage And Release Performance Of Fixed-phase Phase Change Heat Storage Device

The advantages of large phase change latent heat storage capacity and small temperature fluctuation during heat storage and release make phase change energy storage technology have broad application prospects in many fields.However,the phase change material has the disadvantage of low thermal conductivity during use.Adding high thermal conductivity substances to the phase change material is an effective way to make up for this short board.In this paper,a phase change ring is made by compressing expanded graphite/erythritol composite phase change material,and a plurality of phase change rings are combined into a shaped phase change heat storage device,and the heat storage and discharge process of the device is tested and numerically simulated.The specific research content and conclusions are as follows:The original state of the composite phase change material is powder,the phase change mode is solid to solid,the density after compression is 1.1g/cm~3,the phase change temperature of the phase change material measured by DSC and laser thermal conductivity is 117.39?,the latent heat is 308.7J/g,thermal conductivity is 4.644?4.385W/(m??).The addition of expanded graphite increases the thermal conductivity of the composite phase-change material compared with pure erythritol by 6 to 13 times,while it has little effect on the phase-change temperature and phase-change latent heat.Designed and built an experimental system,designed three kinds of heat storage experiments with different heating powers,and exothermic experiments with five different inlet temperatures and five different inlet flow rates for the heat exchange fluid.According to the experimental results,a preliminary analysis of the heat storage and release process was carried out,and the supercooling degree of the material was found to be between 10?12°C during the experiment.The physical model of the heat storage device is simplified.The Fluent software is used to numerically simulate the heat storage and release process of the device,and the accuracy of the model is verified.Through the data collection of the relevant measurement points of the model temperature field,the internal temperature changes and heat transfer during the heat storage and discharge process were analyzed.From the perspective of considering the overall operating efficiency of the heat storage device,the numerical simulation results are used to calculate and analyze the cycle heat efficiency and heat release efficiency under different heat release conditions.In addition,by calculating and analyzing the cycle heat efficiency and heat release efficiency of heat storage devices with different sizes,it can provide guidance for the optimal design of subsequent heat storage devices and achieve the effect of saving mold manufacturing costs.