Preparation And Properties Of Stereotyped Composite Phase Change Materials With Disodium Hydrogen Phosphate Dodecahydrate

With the continuous development of economic globalization,China is faced with the dilemma of energy shortage.Therefore,it is urgent to optimize energy structure and realize energy efficient storage.In the field of building energy consumption,inorganic hydrated salts in solid-liquid variable materials have attracted extensive attention due to their advantages of high latent heat,environmental protection and low cost.But inorganic hydrated salt has some problems,such as phase separation,high supercooling,phase variation and leakage,which restrict its practical application.In this paper,inorganic hydrated salts Na₂HPO₄·12H₂O（DHPD）,Na₂S₂O₃·5H₂O（STP）and Na₂CO₃·10H₂O（SCD）were firstly compounded,and nano Ti O₂ was used as nucleating agent to study the mechanism of phase-free separation and the variation of the degree of supercooling.Phase separation did not occur in Ternary Eutectic Hydrate Salt（TEHS）when DHPD:STP:SCD=8:1:1（S8）.The reason for phase separation was analyzed by co-ion effect.The degree of supercooling firstly decreased and then increased with the increase of Ti O₂ dosage.The optimal dosage was 0.5wt%,while the degree of supercooling of TEHS was only 1.1℃.After modification,TEHS was nucleated inhomogeneously with Ti O₂ particles as substrate,and Ti O₂ and TEHS were physically mixed.The melting enthalpy and solidification enthalpy decreased by 0.50%and 0.55%respectively after modification.Then Ti O₂@TEHS/AHMSEP was prepared by vacuum impregnation using Acid Heat Modification Sepiolite（AHMSEP）adsorbed with phase change material.The effect of modification conditions on the change of adsorption rate and the thermal properties of Ti O₂@TEHS/AHMSEP were studied.The results showed that the highest adsorption rate was 62.0%,and the best modification conditions were 0.6mol/L HCl acided for 6h and 400℃heated for 2h.AHMSEP and Ti O₂@TEHS were physically mixed.The melting enthalpy of Ti O₂@TEHS/AHMSEP was 130.7J/g,and the solidification enthalpy was 128.5J/g.After 200 cycles,the enthalpy of fusion was126.5J/g,which decreased to 96.79%of that before the cycle.The enthalpy of solidification was 123.8J/g,which decreased to 96.34%of that before the cycle.Finally,the plasterboard with phase change energy storage was prepared by direct mixing method,and the influence of the amount of phase change material on temperature regulation effect and mechanical properties was investigated.The results showed that the temperature regulating effect of plasterboard becomes better with the increase of phase change material content.Water absorption rate increased with the increase of phase change material content.When the content was less than or equal to10%,it meeted the requirements in JC/T 799-2007 decorative Gypsum Board.The flexural and compressive strength decreases with the increase of the content of phase change material.When the content of phase change material was 15%,the flexural strength value was 2.11MPa and the compressive strength value was 6.17MPa,which meeted the requirements of first-class products in GB/T 9776-2008.According to the comprehensive temperature regulation effect and mechanical properties,when the PCM content was 10%,the prepared PCM plasterboard had good temperature regulation effect and meeted the requirements of mechanical properties,with the best performance and great application potential.