Abstract Nano-encapsulated phase change materials (NEPCMs) are known to enhance the thermal characteristics of fluids; therefore, there is a rising interest in employing these materials in future thermal control systems. This paper investigates hydrodynamic and thermal characteristics of nanofluids, NEPCMs mixed in the host liquid, in glass balls as a porous structure. The geometry is a two-dimensional porous square cavity in which the left boundary is hot, the right boundary is cold, and the horizontal ones are considered to be insulated. The NEPCMs are composed of polyurethane (PU) as shell and nonadecane as a core. The impact of different non-dimensional parameters, such as Darcy number, 10−5 ≤ Da ≤ 10−1, porosity, 0.4 ≤ ɛ ≤ 0.9, Stefan number, 0.2 ≤ Ste ≤ 100, fusion temperature, 0 ≤ θf ≤ 1, and volume fraction of the NEPCMs, 0 ≤ ϕ ≤ 0.05, is studied on the flow and heat transfer characteristics. It is shown that the volume fraction of NEPCMs is directly proportional to the strengthening of the heat transfer rate in such a way that applying 5% volume fraction of NEPCMs could enhance the heat transfer up to 20.1% and 14.1% at θf = 0.5 in comparison to the cases of pure fluid and NEPCM mixture with no core-phase change, respectively. The effect of non-dimensional fusion temperature on the rate of heat transfer is also found to be noticeable. The maximum average Nusselt number emerges at θf = 0.5, which is the optimum fusion temperature.

中文翻译：

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在多孔外壳中包含纳米封装相变材料的悬浮液的热和流体动力学行为

摘要 众所周知，纳米封装相变材料 (NEPCM) 可以增强流体的热特性；因此，在未来的热控制系统中使用这些材料的兴趣越来越大。本文研究了纳米流体的流体力学和热特性，NEPCMs 混合在主体液体中，作为多孔结构的玻璃球。几何是一个二维多孔方腔，其中左边界是热的，右边界是冷的，水平的被认为是绝缘的。NEPCMs 由聚氨酯（PU）为壳，十九烷为核。不同无量纲参数的影响，如达西数，10−5 ≤ Da ≤ 10−1，孔隙率，0.4 ≤ ɛ ≤ 0.9，Stefan 数，0.2 ≤ Ste ≤ 100，融合温度，0 ≤ θf ≤ 1，和 NEPCM 的体积分数，0 ≤ φ ≤ 0.05，研究了流动和传热特性。结果表明，NEPCMs 的体积分数与传热率的增强成正比，相比之下，在 θf = 0.5 时，应用 5% 的 NEPCMs 体积分数可以将传热提高 20.1% 和 14.1%分别为纯流体和 NEPCM 混合物没有核心相变的情况。还发现无量纲熔化温度对传热速率的影响是显着的。最大平均努塞尔数出现在 θf = 0.5，这是最佳融合温度。结果表明，NEPCMs的体积分数与传热率的增强成正比，相比之下，应用5%体积分数的NEPCMs可以将传热提高20.1%和14.1%，θf = 0.5分别为纯流体和 NEPCM 混合物没有核心相变的情况。还发现无量纲熔化温度对传热速率的影响是显着的。最大平均努塞尔数出现在 θf = 0.5，这是最佳融合温度。结果表明，NEPCMs 的体积分数与传热率的增强成正比，相比之下，在 θf = 0.5 时，应用 5% 的 NEPCMs 体积分数可以将传热提高 20.1% 和 14.1%分别为纯流体和 NEPCM 混合物没有核心相变的情况。还发现无量纲熔化温度对传热速率的影响是显着的。最大平均努塞尔数出现在 θf = 0.5，这是最佳融合温度。