相变储能充填体强度与热学性能

Strength and thermal performance of phase change energy storage backfill

以硬脂酸丁酯为相变材料、膨胀珍珠岩为吸附介质制备复合相变材料,将其按一定质量分数替代尾砂后与水泥、尾砂混合制成相变储能充填体。为探究相变储能充填体强度和热学性能表现,分别制备不同灰砂比、质量分数和复合相变材料质量分数添加量的相变储能充填体,并采用DSC、SEM、单轴压缩试验、巴西劈裂试验和导热系数试验等测试方法得到不同配比相变储能充填体的强度特征、导热系数及微观特征。结果表明:相变储能充填体内存在3种孔隙结构,分别为微小气泡、胶结物质与复合相变材料黏结裂隙以及膨胀珍珠岩内部多孔结构。灰砂比1∶6制备的充填体强度约为1∶4充填体强度值的1/2;相同配比时质量分数由68%增加到72%,其强度近似线性增加;充填体强度随复合相变材料添加量的增大逐渐下降,但下降趋势随添加量继续增大而有所减缓。复合相变材料与硬脂酸丁酯相比相变温度下降1.1℃,相变焓值减少45.24 J/g,比热容不变,添加复合相变材料后相变储能充填体导热系数最大下降幅度为6.5%。

A composite phase change material was prepared with butyl stearate as phase change material and expanded perlite as adsorption medium,and then it was mixed with cement and tailings to make phase change energy storage filling body.In order to explore the strength and thermal performance of the phase change energy storage fillings,phase change energy storage fillings with different ratios of ash to sand,mass fractions,and additive amounts of mass fractions of composite phase change materials were prepared,and the strength characteristics,thermal conductivity,and microscopic characteristics of phase change energy storage fillings with different ratios were obtained by DSC,SEM,uniaxial compression test,Brazilian splitting test,and thermal conductivity test.Research results show that there were three kinds of pore structures in the phase change energy storage filling body:tiny bubbles,bonding cracks between cementing materials and composite phase change materials,and porous structures in expanded perlite.The strength of the filling body prepared with the ratio of lime to sand of 1∶6 was about 1/2 of that of the filling body of 1∶4.When the mass fraction increased from 68%to 72%at the same ratio,its intensity increased approximately linearly.The strength of the backfill gradually decreased with the increase of the additive amount of composite phase change material,but the downward trend slowed down with the continuously increase of the amount of composite phase change material.Compared with butyl stearate,the phase change temperature of the composite phase change material decreased by 1.1℃,the enthalpy of phase change decreased by 45.24 J/g,and the specific heat capacity remained unchanged.After adding the composite phase change material,the thermal conductivity of the phase change energy storage filling body decreased by 6.5%.