磷石膏基复合相变材料的制备及储热性能研究

以磷石膏为原料,采用常压盐溶液法在硝酸镁溶液中制备α-半水石膏,以凹凸棒土和聚氨酯为载体、十水硫酸钠和结晶乙酸钠二元共晶水合盐为相变材料,采用真空吸附法制备定形相变材料,然后将α-半水石膏与定形相变材料复合制备磷石膏基相变材料,并考察了其机械强度和储放热性能。结果表明,由磷石膏制备的α-半水石膏抗折、抗压强度分别为8.9、36.8 MPa,定形相变材料的相变温度为28.5 ℃,相变焓为82.6 J/g。由于掺入相变材料导致石膏晶体结合点减少,磷石膏基相变材料抗压强度降低,但其仍然能够达到建筑石膏的使用要求。升、降温实验结果表明,磷石膏复合相变材料与纯磷石膏保温箱相比,温差为8.9 ℃,具有一定的储能效果。

Study on preparation and heat storage performance of phosphogypsum-based composite phase change materials

α-hemihydrate gypsum was prepared from phosphogypsum as raw materials in magnesium nitrate solution by the atmospheric salt solution method.With attapulgite and polyurethane used as the carrier,sodium sulfate decahydrate and crystalline sodium acetate binary eutectic hydrated salt used as the phase change materials,the form-stable phase change materials were prepared by the vacuum adsorption method.Then the α-hemihydrate gypsum and the form-stable phase change materials were combined to prepare the phosphogypsum-based phase change materials,and their mechanical strength and heat storage-release properties were investigated.The results showed that the bending strength and compressive strength of α-hemihydrate gypsum prepared from phosphogypsum were 8.9 MPa and 36.8 MPa,respectively.The phase change temperature of the shaped phase change material was 28.5 ℃,and the phase change enthalpy was 82.6 J/g.The compressive strength of the phosphogypsum-based phase change material was decreased due to the reduction of the gypsum crystal bonding points caused by the incorporation of the phase change material,but it still could meet the requirement of the use of building gypsum.The results of the heating and cooling experiments showed that the phosphogypsum composite phase change material had a certain energy storage effect compared with the pure phosphogypsum incubator with the temperature difference of 8.9 ℃.