摘要
以Stefan半无限大理论为基础,建立柱坐标系下一维径向相变传热的数学模型;运用摄动法推导相变材料熔点处液相热导率与相界面移动规律之间的测量模型,基于此模型设计一套测量相变材料熔点附近热导率的测量系统。采用相变蓄热系统中常用的结晶水合盐——八水氢氧化钡作为实验对象,分别在热边界温度为356,361和366 K时进行实验,通过测量相界面的移动变化规律,计算得到相变材料的热导率。研究结果表明:在这3个热边界温度下,相变材料液相热导率测量平均值分别为0.673,0.658和0.651 W·m-1·K-1;采用该方法进行测量时,只需控制热源边界温度,无需测量热流密度,1次实验即可获得多组热导率,测量精度较高,具有较强实用性。
A new one-dimensional radial model was established based on the Stefan model. With the application of perturbation, the relationship between the thermal conductivity and the evolution of phase change interface was deduced. According to this relationship, a test system was designed to determine the thermal conductivity near the melting point of phase change materials. Barium hydroxide that was commonly used as materials in heat storage system was selected to obtain the thermal conductivity on the phase interface evolution at three boundary temperatures of 356, 361 and 366 K. The results show that the three average thermal conductivities are 0.673, 0.658 and 0.651 W·m-1·K-1, respectively. During the measurement, the control of boundary temperature is required, and the boundary heat flux needn't be measured, and multiple sets of thermal conductivity can be obtained from a single test with high accuracy, so the proposed method has good applicability.
引文
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