Construction And Performance Control Of Porous Hydroxyapatite Ceramic-based Composite Phase Change Energy Storage Materials

Phase change energy storage materials have the advantages of high energy storage density,relatively constant temperature,suitable phase change temperature,significant energy-saving effect,small size,and easy control,etc.However,solid-liquid phase change energy storage materials are unstable in shape during the phase change process,which affects their scope of application.In order to solve this problem,this paper used a Pickering emulsion template to prepare porous hydroxyapatite ceramics with a three-dimensional interconnected micron-level pore structure.The heat storage behavior and the application value of composite phase change energy storage materials were evaluated.The main results obtained in the thesis are:The study of porous hydroxyapatite porous ceramics prepared with Pickering emulsion as a template found that when the p H value was 10 and the sintering temperature was 1300°C,the performance of the porous ceramics was the best.And by adjusting the solid content,the pore size was adjusted from 5 ?m to 30 ?m.This research overcame the shortcomings of traditional porous ceramic preparation methods of large pore size span and uneven distribution and provided support for realizing the encapsulation of phase change materials and studying the influence of matrix pore structure on phase change materials.Using porous hydroxyapatite ceramics as a matrix,polyethylene glycol was encapsulated in the porous ceramic matrix by a vacuum impregnation method to prepare a composite phase change material.Under the action of capillary force,surface tension,and hydrogen bonds,polyethylene glycol was adsorbed on the surface of the porous support material and was confined in the pore structure of the matrix so that it did not leak during the melting process.The composite phase change material obtained by encapsulating the matrix prepared with a solid content of 40 wt.%had good thermal properties,and its latent heat was 117.5 J/g,and after thermal cycling,it still maintained good heat storage performance.Using porous hydroxyapatite ceramics as the matrix,the disodium hydrogen phosphate dodecahydrate/porous hydroxyapatite ceramics composite phase change material was prepared by the melt dipping method to explore the phase change behavior of inorganic phase change materials.The two had good wetting properties,which made the porous matrix have excellent adsorption of water and salt,which could effectively prevent the phase change material from leaking.When the pore size of the porous matrix was less than 5.47 ?m,it can significantly promote the crystallization process of water and salt,and effectively solve the problem of supercooling during the phase transition of water and salt.The latent heat was 177.1 J/g,and after thermal cycling,the latent heat of the sample was only reduced by 0.83%.In summary,the porous hydroxyapatite ceramic prepared by using Pickering emulsion as a template has uniformly connected micron pores and has a good affinity with polyethylene glycol and disodium hydrogen phosphate dodecahydrate.The phase change material can be confined to the collective pore structure,which was beneficial to suppress the leakage of the phase change material,and shows a good application prospect.