Abstract The present study is devoted to the numerical analysis of entropy generation in the natural convection of water combined with nano-sized particles containing the encapsulated phase change material in a square enclosure with a solid triangular block. The finite element method is used for the current investigation. The effects of the Rayleigh (Ra), Stefan numbers (Ste), thermal conductivity ratio (Rk) and non-dimensional height (LY) of the triangular block, the volume fraction (φ), and the non-dimensional fusion temperature (θf) of the nano-encapsulated phase change materials are reported. The results show that the rate of heat transfer and the total entropy generation enhances with the increment of the thermal conductivity of the solid triangular block and also declines with augmentation of its height. Moreover, the generated entropy intensifies as the volume fraction of the nano-capsules increases. Finally, for high values of the Rayleigh number (Ra = 106), the total entropy generation declines as the non-dimensional fusion temperature (θf) approaches 0.5. In contrast, when the buoyancy force is low (Ra = 104), the total generated entropy elevates as θf → 0.5.

中文翻译：

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纳米包封相变材料增强稀水悬浮液的热流体力学和熵生成分析

摘要 本研究致力于对水与包含封装相变材料的纳米尺寸颗粒结合在带有实心三角形块的方形外壳中的自然对流中熵产生的数值分析。本次调查采用有限元法。瑞利 (Ra)、斯特凡数 (Ste)、热导率 (Rk) 和三角块的无量纲高度 (LY)、体积分数 (φ) 和无量纲熔化温度 (θf) 的影响) 的纳米封装相变材料。结果表明，传热速率和总熵生成率随着实心三角形块体导热系数的增加而增加，并随着其高度的增加而降低。而且，产生的熵随着纳米胶囊体积分数的增加而增强。最后，对于高值的瑞利数 (Ra = 106)，随着无量纲融合温度 (θf) 接近 0.5，总熵生成下降。相反，当浮力低（Ra = 104）时，总生成熵随 θf → 0.5 升高。