Research On Phase Change Thermal Storage Material Based On Solar Heating System

Because of the problems of low heat flux and strong intermittency in solar energy,it is of great significance to apply the method of phase change energy storage to solar heating.This research is mainly based on solar heating system for experimental research and numerical simulation of composite phase change materials.The effects of ultrasonic parameters,repetitive ultrasound,melting process and dispersant on the stability of composite phase change material were analyzed.The results show that the stability of phase change material is enhanced with the increase of ultrasonic power.Repetitive ultrasonic and fusion processes have an adverse effect on the stability of the phase change material.Adding dispersant can enhance the stability of the composite complex.According to the measurement of thermal conductivity of nanocomposites,it was found that the thermal conductivity of pure paraffin increased by 50.7%,33.8% and 11.3% respectively by adding copper oxide,silicon dioxide and zinc oxide.The study of the phase transition characteristics of nanofluids shows that the addition of nano particles can reduce the effect of supercooling.With the change of particle type and mass fraction,the latent heat value presents irregular change,but the latent heat value of nanofluid phase change material is smaller than that of pure paraffin.The experimental research and analysis of the heat storage process of phase change materials outside the cylindrical heating tube are carried out by building a test bed and a data acquisition system.The melting process of pure paraffin outside the circular tube was studied and the temperature change of each measuring point was analyzed.The effects of different wall temperature on the phase transition process were compared.The influence of different nanoparticle types,mass fraction,particle size and remelting conditions on the thermal storage and heat release process of nano composite phase change materials was studied by experimental method.In addition,the circular fin is added to the heat storage tank to carry out the experimental research,and it is compared with the working condition without fins.The results show that the heat transfer ability of the fin reinforcement system can enhance the heat transfer and reduce the time needed for the heat release process.The mathematical model was established to simulate the melting process of copper oxide-paraffin phase-change material in the heat storage tank.The solid-liquid phase diagram of copper oxide-paraffin at different tube wall temperatures was analyzed.The results show that the larger the number of Stephen,the faster the melting rate of phase change material,but with the increase of Stephen number,the improvement of melting rate of phase change material shows a decreasing trend.With the increase of GL number,the melting process is slower,but the effect of the Stephen number on the melting process is greater than that of the GL number.