Investigation On Hexadecylamine And Polyethylene Glycol Based Shape Stabilized Composite Phase Change Materials For Energy Storage Through In-situ Nano-encapsulation

Human has increasingly depended on energy,in order to improve energy utilization efficiency,energy storage materials including phase change materials?PCMs? have been paid more and more attention.Among them,solid-liquid PCM has become the most feasible and practically useful PCMs due to its'high heat storage density and the small change in phase change volume.HDA and PEG are both promising phase change energy storage materials with the high latent heat of phase change and good thermochemical stability.However,the leakage of the liquid when they are melted has limited their practical applications.One of the current approaches to solve the leakage problem is to develop a shape stabilized composite phase change materials?ss-CPCMs?.In this investigation,several ss-CPCMs with PCMs HDA and PEG as core materials are designed and synthesized.The main research content is as follows:?1?The preparation and properties of HDA based ss-CPCMs?a?HDA/SiO₂ ss-CPCMsHDA/SiO₂ ss-CPCMs was prepared with SiO₂ as the wall material,HDA as the core material,and APTES as the coupling agent by the sol-gel method.Single factor investigation was used to optimize the experimental conditions.Orthogonal experiments were performed to verify the properties of the HDA/SiO₂ ss-CPCMs.The optimal experimental results show that APTES as a silane coupling agent successfully connected TEOS with HDA by physical action.FT-IR showed that no new absorption peak appeared in the final product.HDA was successfully coated with SiO₂.The latent heats of melting and solidification were 214.9 J/g and 210.8 J/g,respectively.The loading rate of HDA is 94.4%,The latent heat of melting and solidification of HDA/SiO₂ is basically unchanged after 100 heating-cooling cycles,showing excellent thermal stability.There is no leakage of the material when the composite was heated above its melting point.The thermal conductivity is 0.23 W/m·K,which is about twice as high as that of HDA.?b?HDA/PO₄^3-ss-CPCMsThe hydrothermal method was used to synthesize HDA/PO₄^3-ss-CPCMs with phosphate as the wall material and HDA as the core material.The single-factor investigation and optimized experimental conditions showed that the physical interaction existed between the phosphate and HDA.The phase change enthalpy is higher than 110 J/g,and the thermal conductivity is higher than 0.4 W/?m·k?,which is as 4times as that of HDA.It has high phase change enthalpy and thermal conductivity and good energy storage performance.The coverage rate is 50%.After 100 heating-cooling cycles,the latent heat of melting and solidification of HDA/PO₄^3-ss-CPCMs is basically unchanged,exhibiting excellent thermal stability.?2?The preparation and properties of PEG-based shape stabilized composite phase change materials?ss-CPCMs?PEG/SiO₂ ss-CPCMs were synthesized by the sol-gel method with SiO₂as the wall material,PEG as the core material,and APTES as the coupling agent.The single-factor investigation and optimized experimental conditions showed PEG was successfully coated with SiO₂.The latent heats of melting and solidification of ss-CPCMs were 155.2 J/g and 151.7 J/g,respectively with a three-dimensional network.The coverage rate of PEG is 95.5%.After the second heating-cooling cycle,the melting and solidification latent heat of PEG/SiO₂ is basically unchanged,showing excellent thermal stability.There is no leakage of the composite material when heated above the melting point of PEG.The thermal conductivity is 0.32 W/m·K,which is about three times as high as that of PEG.