| The rapid development of the world economy and technology has also brought enormous pressure on the energy environment,with buildings accounting for an increasing share of energy consumption year on year.The introduction of phase change materials into the building envelope can play a passive role in regulating the indoor temperature environment.Fatty acid and fatty alcohol phase change materials have become a hot research topic in recent years due to their high thermal capacity,safety,non-toxicity and easy availability.However,due to the generally high phase change temperature of single fatty acids and fatty alcohols,they are unable to meet the requirements of temperature regulation and energy storage in buildings,while the leakage problem of solid-liquid phase change materials in use has led to their limited application.The work done in this paper to address the above issues is as follows.（1）CA-OD binary eutectic system was prepared by melt blending method using Capric acid（CA）and Octadecanol（OD）as phase change raw materials,and its optimum mass ratio was determined as m CA:m OD=85:15 by step-cooling curve method guided by theoretical calculation.CA-OD was prepared by Differential Scanning Calorimeter（DSC）,Fourier infrared spectrometer（FT-IR）,Thermogravimetric analyzer（TG）and accelerated thermal cycling experiment.The analysis of the properties and structure of CA-OD shows that CA-OD has the characteristics of chemical temperature,high heat resistance and good cyclic stability,and its phase change temperature is also in the comfortable temperature range for human body,with high latent heat of phase change and good thermal storage and temperature control performance.The microstructure and composition of diatomaceous earth before and after modification were characterised using X-ray powder diffraction（XRD）and SEM,and the results showed that the increase in the concentration of hydrochloric acid solution enhanced its modification effect on diatomaceous earth,with 5 mol/L hydrochloric acid solution increasing the pore size expansion rate of diatomaceous earth.The pore size expansion of diatomaceous earth was the highest with 5 mol/L hydrochloric acid solution.At the same time,no new material was generated in the pores before and after the modification of diatomaceous earth.（2）The CA-OD/DME shaped energy storage phase change material was prepared by vacuum adsorption method,and the optimum adsorption conditions were determined by single-factor and orthogonal tests:m CA-OD:m DME=35:65,adsorption temperature 60℃,adsorption vacuum 0.04MPa,adsorption time 60min.The thermal properties,structural properties and stability of CA-OD/DME were analyzed by DSC,FT-IR,XRD,SEM,TG,accelerated thermal cycling and diffusion-exfiltration circle experiments.At the same time,the PCM is uniformly embedded in the pores of the modified diatomaceous earth,which effectively prevents the leakage of the phase change agent and has good thermal reliability,meeting the requirements for use in the construction field.（3）A series of phase change energy storage gypsum test panels were prepared by incorporating different mass fractions of CA-OD/DME shaped phase change energy storage materials into the gypsum gel material,and the thermal storage performance and stability of phase change energy storage gypsum panels were compared with those of ordinary gypsum panels by using thermal storage performance tests,SEM,accelerated thermal cycling experiments and diffusion-exfiltration circle experiments.At the same time,CA-OD/DME fills the pores between the gypsum gel materials and has a dense and compact structure,which has good cycling stability and thermal reliability and can be applied in the field of building energy saving. |
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