Hot-spot thermal management by phase change materials enhanced by spatially graded metal meshes
Hot-spot thermal management by phase change materials enhanced by spatially graded metal meshes
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DOI：
10.1016/j.ijheatmasstransfer.2019.119153
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发表时间：
2020-04
影响因子：
5.2
通讯作者：
L. Wei;J. Malen
中科院分区：
文献类型：
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作者：
L. Wei;J. Malen
优化了在空间上增强相变材料（PCM）导热性的梯度网格插入，以最小化热源和熔体前之间的时间平均热阻，以提高电子产品的散热率。传统上，通过加入具有高导热系数的空间均匀多孔填料来增强PCM的低导热系数。我们研究了多孔填料在空间分布上增强导热性的相对优势。基于热扩散方程的数值解，优化了空间变化的任意多项式形式，以提高一维球面和柱坐标下的散热率。最理想的空间分布是非线性的，在热点附近具有较高的导热性，并且相对于径向坐标（即凹化）具有正的二阶导数。我们证明了恒温热点的散热率增强，或恒定功率热点的温度降低，在球面和柱坐标下，相对于等效平均体积分数的均匀填料所实现的散热率，提高了900%和300%。增材制造技术的最新进展使得具有空间梯度体积分数的金属网格成为可能。
Graded mesh inserts that spatially enhance the thermal conductivity of phase change materials (PCM) are optimized to minimize the time averaged thermal resistance between the heat source and the melt-front, to improve heat dissipation rates for electronics. Conventionally, the low thermal conductivities of PCM are enhanced by incorporating spatially-homogeneous porous fillers with high thermal conductivities. We investigate the relative advantages of porous fillers that spatially distribute enhancements to thermal conductivity. An arbitrary polynomial form of the spatial variation is optimized based on a numerical solution to the heat diffusion equation, to enhance heat dissipation rates in one-dimensional spherical and cylindrical coordinates. The most desirable spatial distributions are non-linear, have higher thermal conductivity near to the hot-spot, and a positive second derivative with respect to the radial coordinate (i.e. concave-up). We demonstrate enhancements of heat dissipation rates for constant temperature hot-spots, or reductions in temperature for constant power hot-spots, by factors of 900% and 300% in spherical and cylindrical coordinates, relative to those achieved by uniform fillers of equivalent average volume fractions. Recent advances in additive manufacturing make metal meshes with spatially graded volume fraction realizable.