Preparation And Characterization Of SiO₂/PEG Composite With Nano Materials Doping As Shape-stabilized Phase Change Materials

With the increasingly serious energy crisis, phase change materials（PCMs） has obtained more and more extensive research and application as a new type of efficient energy storage material. Organic PCMs has become the most potential phase change energy storage material for its high phase change latent heat,stable physical and chemical properties and popular price. Polyethylene glycol（PEG）, a kind of organic PCMs, has good performances like appropriate phase transition temperature of56⁶3℃and latent heat of phase change of 179.7J/g. But PEG is easy to leak when the solid liquid phase change and has poor heat transfer property, which limit its application severely.In order to improve the performance of the PEG, three kinds of heat conduction enhanced composite phase change materials were prepared in this paper: with PEG as organic phase change component for energy store, SiO₂ as inorganic skeletal implementations to finalize the design, nano Ag, nano ZnO and nano CeO₂ as heat conduction enhancement component, heat conduction enhanced composite phase change materials of Ag-SiO₂/PEG、ZnO-SiO₂/PEG �'� CeO₂-SiO₂/PEG were prepared in in-situ polymerization and sol-gel method, and studied through a variety of testing methods on the performance of the composite PCMs. Research is divided into 3aspects:1. Ag-SiO₂/PEG thermal enhanced composite phase change materials was prepared in in-situ polymerization and sol-gel method, and studied through XRD、FTIR、DSC、TG and thermal conductivity tester on the performance. The results prove that PEG is physical combined with Ag and SiO₂, crystallization performance of PEG is affected by the inorganic network structure; with the increase of content of nano Ag,thermal conductivity of composite material rises. When the quality of Ag doping ratio is 6%, thermal conductivity of composite material is 0.4315W/m·k, 46.37% higher than that of PEG6000, 40.14% higher than Si O₂/PEG; phase change latent heat is121.24J/g, thermal stability is as high as 330℃ with no volatilization and no resolve.2. ZnO-SiO₂/PEG thermal enhanced composite phase change materials was prepared, with nano ZnO treated by butyl titanate firstly as doped phase, in sol-gel method with assistance of ultrasonic wave. The results prove that treatment of butyl titanate can effectively improve the dispersion and stability of ZnO in the solvent; doping of ZnO and SiO₂ reduces the crystallization properties of the PEG.With the increase of content of nano ZnO, thermal conductivity of composite material rises. When the quality of ZnO doping ratio is 6%, thermal conductivity of composite material is 0.3306 W/m·k, 7.24% higher than that of SiO₂/PEG,12.01% higher thanPEG6000; phase change latent heat is 123.36J/g, thermal stability is as high as 330℃with no volatilization and no resolve.3. CeO₂-SiO₂/PEG thermal enhanced composite phase change materials was prepared, with nano CeO₂ treated by sodium hexametaphosphate firstly as doped phase, in sol-gel method with assistance of ultrasonic wave. The results prove that treatment of sodium hexametaphosphate can effectively improve the dispersion and stability of CeO₂ in the solvent; doping of CeO₂ and SiO₂ reduces the crystallization properties of the PEG. With the increase of content of nano CeO₂, thermal conductivity of composite material rises. When the quality of CeO₂ doping ratio is 6%,thermal conductivity of composite material is 0.3357 W/m·k, 9.03% higher than that of SiO₂/PEG,13.88% higher than PEG6000; phase change latent heat is 119.24 J/g,thermal stability is as high as 330℃ with no volatilization and no resolve.