Han Dongxu, Yue Kai, Cheng Liang, Yang Xuri, Zhang Xinxin
School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China.
Materials (Basel). 2020 Mar 17;13(6):1353. doi: 10.3390/ma13061353.
A novel method involving the effect of thermal contact resistance (TCR) was proposed using a plane heat source smaller than the measured samples for improving measurement accuracy of the simultaneous determination of in-plane and cross-plane thermal conductivities and the volumetric heat capacity of anisotropic materials. The heat transfer during the measurement process was mathematically modeled in a 3D Cartesian coordinate system. The temperature distribution inside the sample was analytically derived by applying Laplace transform and the variables separation method. A multiparameter estimation algorithm was developed on the basis of the sensitivity analysis of the parameters to simultaneously estimate the measured parameters. The correctness of the algorithm was verified by performing simulation experiments. The thermophysical parameters of insulating materials were experimentally measured using the proposed method at different temperatures and pressures. Fiber glass and ceramic insulation materials were tested at room temperature. The measured results showed that the relative error was 1.6% less than the standard value and proved the accuracy of the proposed method. The TCRs measured at different pressures were compared with those obtained using the steady-state method, and the maximum deviation was 8.5%. The thermal conductivity obtained with the contact thermal resistance was smaller than that without the thermal resistance. The measurement results for the anisotropic silica aerogels at different temperatures and pressures revealed that the thermal conductivity and thermal contact conductance increased as temperature and pressure increased.
提出了一种涉及热接触电阻（TCR）效应的新方法，该方法使用比被测样品小的平面热源，以提高同时测定各向异性材料的面内和面外热导率以及体积热容的测量精度。在三维笛卡尔坐标系中对测量过程中的热传递进行了数学建模。通过应用拉普拉斯变换和变量分离法解析得出了样品内部的温度分布。在对参数进行灵敏度分析的基础上开发了一种多参数估计算法，以同时估计被测参数。通过进行模拟实验验证了该算法的正确性。使用所提出的方法在不同温度和压力下对绝缘材料的热物理参数进行了实验测量。在室温下对玻璃纤维和陶瓷绝缘材料进行了测试。测量结果表明，相对误差比标准值小1.6%，证明了所提方法的准确性。将不同压力下测得的热接触电阻与使用稳态法获得的热接触电阻进行了比较，最大偏差为8.5%。有接触热阻时获得的热导率小于无热阻时的热导率。对不同温度和压力下各向异性二氧化硅气凝胶的测量结果表明，热导率和热接触传导率随温度和压力的升高而增加。
