The Preparation And Performance Research Of Sodium Thiosulfate Pentahydrate/Sepiolite Phase Change Thermal Storage Material

Currently,the environmental pollution and energy crisis has become a global hot issue.Unfortunately,buildings(either commercial or residential)play a pivotal role in increasing fossil fuel consumption.Therefore,improving the energy efficiency of buildings has become a top priority.In the field of energy-saving construction,phase change materials(PCMs)with high density for thermal energy storage can be efficiently employed to this purpose,which can also reduce fossil fuel consumption.Due to the phase change materials in thepresence of supercooling,phase separation and leakage,this paper put forward the notion that is making a building heating phase change thermal storage material by the link of sodium thiosulfate pentahydrate(Na2S2O3·5H2O)and sepiolite.The mainly work as follow:1 In order to solve its problems of supercooling and phase separation,this experiment chooses a variety of nucleating agents and thickening agents on sodium thiosulfate pentahydrate to prepare for a modified phase change thermal storage material.At the same time,a orthogonal test method is used to obtain the best ratio of the two nucleating agents calcium sulfate(CaSO4·(2H2O),zinc oxide(ZnO)and the thickening agent carboxymethyl cellulose(CMC)for modifying sodium thiosulfate pentahydrate.The result is that the ratio of 6%CaSO4-2H2O,4%ZnO and 2%CMC has the best performance.2 Through the experimental study on the modification of acid and heating treatment of sepiolite,the optimum conditions of the acid and heating treatment is found,which is 5mol/L HCl,stirring 24h at 25 OC.TiO2-sepiolite porous matrix material is made to improve the hydrophilicity and water vapor adsorption capacity of sepiolite.3 In order to solve the problem of water evaporation in the heating process of phase change thermal storage material,sodium thiosulfate pentahydrate/TiO2-sepiolite phase change thermal storage material is prepared by the link of sodium thiosulfate pentahydrate and TiO2-sepiolite porous matrix material.At the same time,using simultaneous thermal analyzer,scanning electron microscope(SEM),and X ray diffraction(XRD),analysis of the material properties.Then we know the best selected content of TiO2-sepiolite is 40%.4 Finally,multiple melting-cooling cycle experiment is taking for composite phase change system.The research results show that its phase change enthalpy is 176.85J/g,only declined 7.79%,and the weight loss rate is 7.53%,after been carried out in 250 heating and cooling cycles.TiO2-sepiolite can effectively prevent water loss and phase separation,prolonged using time.