琼脂糖-刺槐豆胶/水合盐共晶定形 相变材料的制备及性能

Preparation and application of agarose-locust bean gum/hydrated salt eutectic form-stable phase change materials

摘要:

无机水合盐的共晶体系可有效调节相变温度,拓展体系的应用领域,但难以从根本上解决体系相分离难题。相分离的本质在于部分无机盐溶解度低,脱除结晶水后变成无水盐,在相变过程中难以有效溶解,从体系中脱离并沉淀。本研究以提高相变过程中固态无机盐的溶解度为策略,在十水合硫酸钠(SSD)和十二水合磷酸氢二钠(SPDD)共晶体系中额外增加质量分数为 13% 的水,消除了体系的相分离现象；并以 3% Na₂SiO₃?9H₂O 为成核剂将体系过冷度降低至 0.16 ℃。在此基础上,以琼脂糖-刺槐豆胶(AG-LBG)三维网络结构作为支撑骨架,采用浸渍法负载上述相变体系,制备了负载率为 85% 的定形相变材料(SSPCM),有效解决了固-液相变过程中存在的漏液问题。定形相变材料 SSPCM 的相变温度为 26.40 ℃,相变焓值为 147.20 J/g,热导率为 0.11 W/(m?K)。在相同时间内进行保温效果模拟测试,与泡沫夹层相比,复合相变材料SSPCM 将建筑内部中心温度的升温时间延长了 3.60 倍,降温时间延长了 2.37 倍,具有优异的控温效果。

Abstract:

The eutectic system of inorganic hydrated salts can effectively adjust the phase transition temperature and expand the application field of the system, but it is difficult to fundamentally solve the problem of phase separation of the system. The essence of phase separation lies in the low solubility of some inorganic salts, which become anhydrous salts after the removal of crystal water, which are difficult to dissolve effectively during the phase transition process, break away from the system and precipitate. In this study, 13% water was added to sodium sulfate decahydrate (SSD) and disodium hydrogen phosphate (SPDD) eutectic system to improve the solubility of solid inorganic salts during phase transformation. Using 3% Na₂SiO₃?9H₂O as nucleating agent, the supercooling degree of the system was reduced to 0.16 ℃. On this basis, using agarose-locust bean gum (AG-LBG) three-dimensional network structure as the supporting skeleton, the phase change system was loaded by impregnation method, and the form-stable phase change material (SSPCM) with the loading rate of 85% was prepared, which effectively solved the problem of liquid leakage in the solid-liquid phase change process. The phase transition temperature, enthalpy and thermal conductivity of SSPCM are 26.40 ℃, 147.20 J/g and 0.11 W/(m?K). The simulation test of thermal insulation effect in the same time shows that, compared with foam sandwich, the heating time of the core temperature inside the building is extended by 3.60 times, and the cooling time is extended by 2.37 times, which has excellent temperature control effect.