不同粒径膨胀蛭石制备复合相变材料试验研究

Experimental Study on Preparation of Composite Phase Change Materials by Expanded Vermiculite with Different Particle Sizes

以六水氯化钙为相变材料(PCM),3种粒径范围的膨胀蛭石为支撑材料,制备了复合相变材料。研究膨胀蛭石粒径对复合相变材料的吸附量及热物理性能的影响。运用XRD、SEM、FT-IR分别研究了相变材料的物相、复合相变材料的微观形貌及组成。结果表明:CaCl_2·6H_2O是一种结晶性能好、相变温度适中且潜热较高的相变材料;膨胀蛭石是一种优异的支撑材料,CaCl_2·6H_2O能很好地吸附在其片层间隙中;3种复合相变材料的相变温度都约为28℃,对CaCl_2·6H_2O的最优吸附量分别为55%、60%和50%,对应相变潜热分别为106.04 J/g、112.93 J/g和94.46 J/g。中等粒径(0.25~0.55 mm)复合相变材料的相变材料吸附量最大,相变潜热值最高。复合相变材料经100次冷热循环后的潜热损失率随着粒径减小呈降低趋势。

The composite phase change materials（PCM） were prepared using CaCl2·6H2O as phase change material and three kinds of particle size expanded vermiculite as supporting material. The effects of different particle size range of the expanded vermiculite on the optimum adsorption capacity and thermal physical properties of the composite PCM were investigated. The phase change material was analyzed by the XRD. The microstructure and composition of the composite PCM were investigated by the SEM and the FT-IR, respectively. The results showed that CaCl2·6H2O was a kind of phase change material with good crystalline properties, moderate phase transition temperature and high latent heat. The fact that CaCl2·6H2O was successfully embedded in the space layer of the expanded vermiculite confirmed that EV was considered to be an excellent supporting material. The prepared composite PCM had a phase transition temperature of about 28 ℃. The optimum adsorption capacity of CaCl2·6H2O of the composite PCM were 55%, 60%, 50%, and the corresponding latent heats were 106.04 J/g, 112.93 J/g and 94.46 J/g, respectively. Among them, the medium-sized（0.25-0.55 mm） composite PCM had the largest adsorption capacity and the highest phase change latent heat value. The latent heat loss rate of composite PCM decreases with decreasing particle size of the expanded vermiculite after 100 cold-thermal cycles.