Na_2SO_4·10H_2O/EG复合相变材料的制备与性能分析

以十水硫酸钠为相变材料,采用真空吸附法制备十水合硫酸钠/膨胀石墨复合相变储能材料(Na_2SO_4·10H_2O/EG),对其融化-凝固、相分离、过冷、潜热等热物性进行测试分析。结果表明:在Na_2SO_4·10H_2O中添加2%(质量分数,下同)硼砂和8%EG后,可得到理想的Na_2SO_4·10H_2O/EG固-固复合相变材料。此时,Na_2SO_4·10H_2O相分离得到消除,过冷度由13.6℃降低到0.6℃以下,相变潜热和体储能密度分别为225.77kJ·kg~(-1)和218.09MJ·m~(-3)。此外,导热率也得到提高,相比于只添加成核剂硼砂的Na_2SO_4·10H_2O PCM,储热时间缩短52.6%,放热时间缩短55.1%,经过500次急剧升温-降温循环后也未出现性能衰减,储/放热性能较好。

Preparation and Performance Analysis of Na2SO4·10H2O/EG Composite Phase-change Materials

Sodium sulfate decahydrate/expanded graphite composite phase-change material (Na2SO4·10H2O/EG) was prepared by vacuum adsorption method.The thermal properties of Na2SO4 · 10H2O/EG,such as melting-solidification,phase separation,supercooling and latent heat were tested and analyzed.The results show that with the addition of 2％ (mass fraction) borax and 8％EG,the composite phase-change materials Na2SO4 · 10H2O/EG obtain ideal properties.The phase separation is eliminated,the supercooling degree of Na2SO4 ·10H2O is reduced from 13.6℃ to below 0.6℃,the latent heat and the energy storage density of the phase change materials reach 225.77kJ · kg-1 and 218.09MJ · m-3 respectively.The thermal conductivity is also greatly improved.Compared with Na2SO4 · 10H2O with the addition of the nucleating agent borax only,the time for heat storage is shortened by 52.6％,and the time for heat release is shortened by 55.1％.Even after 500 times of rapid heating and cooling cycles,the performance of Na2SO4 · 10H2O/EG does not deteriorate.The novel composite phase change material has better storage/exothermic properties.