Heat Conduction of a Porous Material
Heat Conduction of a Porous Material
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DOI：
10.1115/1.4005709
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发表时间：
2012-05-01
影响因子：
--
通讯作者：
Nagai, Daisuke
中科院分区：
文献类型：
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作者：
Miyazaki, Koji;Tanaka, Saburo;Nagai, Daisuke
在这项研究中，我们介绍了使用多孔材料降低导热系数的数值和实验工作。近年来，降低热导率已成为提高热电材料品质因数（ZT）的关键技术之一。我们对多孔材料中的热传导进行数值计算，例如声子玻尔兹曼输运（BTE）和分子动力学（MD）模拟，以研究多孔材料导热系数降低的机制。在BTE中，我们应用恒定热通量的周期性边界条件来计算多孔材料的有效导热系数。在MD模拟中，我们利用恒温下的Stillinger-Weber势以及x、y和z方向的周期性边界条件计算了Si的声子特性。由时空二维FFT MD结果计算出的Si单晶声子色散曲线与参考数据吻合较好。此外，还讨论了纳米多孔结构对声子群速度和声子态密度（DOS）的影响。最后，我们用珠磨法制备的纳米粒子制备了多孔p型Bi2Te3。导热系数是散装材料的五分之一，并且保持与散装材料相同的塞贝克系数。然而，电导率大大降低，ZT仅为0.048。 [DOI：10.1115/1.4005709]
In this study, we introduce our numerical and experimental works for the thermal conductivity reduction by using a porous material. Recently thermal conductivity reduction has been one of the key technologies to enhance the figure of merit (ZT) of a thermoelectric material. We carry out numerical calculations of heat conduction in porous materials, such as phonon Boltzmann transport (BTE) and molecular dynamics (MD) simulations, in order to investigate the mechanism of the thermal conductivity reduction of a porous material. In the BTE, we applied the periodic boundary conditions with constant heat flux to calculate the effective thermal conductivity of porous materials.In the MD simulation, we calculated the phonon properties of Si by using the Stillinger-Weber potential at constant temperature with periodic boundary conditions in the x, y, and z directions. Phonon dispersion curves of single crystal of Si calculated from MD results by time-space 2D FFT are agreed well with reference data. Moreover, the effects of nanoporous structures on both the phonon group velocity and the phonon density of states (DOS) are discussed. At last, we made a porous p-type Bi2Te3 by nanoparticles prepared by a beads milling method. The thermal conductivity is one-fifth of that of a bulk material as well as keeping the same Seebeck coefficient as the bulk value. However, electrical conductivity was much reduced, and the ZT was only 0.048. [DOI: 10.1115/1.4005709]