Prepararion And Characterazation Of Phase Change Material Composites For Energy Storage Based On 1-hexadecylamine And Stearic Acid

Energy becomes more and more crucial in modern society with the evolution of economic globalization and the rapid upgrading of science and technology.Efficient energy utilization solutions and new energy storage materials have been recently raised a greater interest to fulfill the huge energy demand as the energy crisis is becoming more and more serious.The application of phase change materials?PCMs?is an efficient way for thermal energy storage since they have large heat storage capacity and can store energy in isothermal process.Especially,solid-liquid PCMs have been extensively applied in many fields.In spite of its small change in phase change volume,these bulk PCMs turn to liquid during the phase change transition when melting which limits their applications to a large extent.Packaging the PCMs is one of the ways to solve the problem.This paper is devoted to prepare the PCM composites based on 1-hexadecylamine?HDA?and stearic acid?SA?for energy storage with large latent heat,good thermal stability,good packaging performance by simple preparation method.The influence of reaction conditions on the preparation and energy storage properties of PCM composites was studied.The main research contents include:?1?Preparation and properties of HDA@SiO₂ compositeHDA@SiO₂ composite was prepared by sol-gel method with HDA as the core material for latent heat storage.And tetraethyl orthosilicate was used as silicon source to synthesize package material which prevented the leakage of the melted HDA.The experimental scheme was developed according to orthogonal test method,and the experimental conditions were optimized to synthesize the HDA@SiO₂ composite.The results indicated that core-shell structured HDA@SiO₂ composite was successfully synthesized,and HDA was encapsulated in SiO₂ shell with physical interactions between them.The latent heats of melting and freezing for HDA@SiO₂ composite are 193.8 J/g and 189.3 J/g,respectively,which has been the highest latent heat in literature up to now.The encapsulation rate is 89 wt%.After 100 cycles,the melting and solidification latent heat of HDA@SiO₂ decreased by 0.46%and 0.16%,respectively.The thermal conductivity is 0.13 W/m·K,which increased by about 12%compared with the pure HDA.The composite also has good thermal reliability and thermal stability without the performance degradation of energy storage.?2?Preparation and properties of HDA@TiO₂ compositeHDA@TiO₂ composite was prepared by sol-gel method with HDA as the core material for latent heat storage.And tetrabutyl titanate was used as titanium source to synthesize package material which prevented the leakage of the melted HDA.The experimental conditions were optimized to synthesize the HDA@TiO₂ PCM composite.The results showed that HDA was successfully encapsulated by TiO₂ with physical interactions between them.The phase transition enthalpy of HDA@TiO₂PCM composite is about 202.5 J/g,which is about 16%higher than the HDA@SiO₂ composite.The thermal conductivity is 0.15 W/m·K,about30%higher than pure phase HDA,The composite also has good thermal reliability and thermal stability without the degradation of energy storage.?3?Preparation and properties of SA@SiO₂ compositeSA@SiO₂ composite was prepared by sol-gel method with SA as the core material for latent heat storage.And tetraethyl orthosilicate was used as silicon source to synthesize package material which prevented the leakage of the melted SA.The experimental conditions were optimized to synthesize the SA@SiO₂ PCM composite.The results showed that core-shell structured SA@SiO₂ composite was successfully synthesized,and SA was encapsulated in SiO₂ shell with physical interactions between them.The phase transition enthalpy of the composite phase change energy storage material is about 208.3 J/g,which is close to the phase transition enthalpy of pure phase SA and there is no leakage phenomenon.It can be seen that the thermal stability of SA@SiO₂ PCM composite is better than that of the pure phase SA from the TGA curve.