Abstract This paper investigated the heat transfer from a wall-affected non-spherical particle to the turbulence gas flow both numerically and experimentally. In the numerical section, a three-dimensional finite element method was used to solve the partial equations using FEMLAB version 2.3. In the experimental section, the axial flow over a single naphthalene particle with the tube to particle diameter ratio (N) ranging within 4.5–6.7 was examined and the Nusselt number was calculated by heat and mass transfer analogy. The effects of the tube wall, particle shape, and particle rotation angle were tested on the formation of hot zones in detail. The results indicated that the wall effect can be ignored when particle-tube wall distance per particle diameter was greater than 0.143 (yc/Dp ≥ 0.143). Internal holes did not play an important role in reducing the hot zones though they increased the heat transfer rate per unit volume of the particle and reduced the pressure drop due to the higher porosity of packed bed. The minimum hot zones were observed for the tri-lobe particle at the axial rotation angle of zero when the particle leaned against the wall tangentially. The predicted results were well congruent with the experimental results. The results obtained by this study can be applied to discovering more about the hot spots and obtain a better catalyst particle for packed bed reactors.

中文翻译：

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靠近床壁的颗粒-流体传热：颗粒形状对热区形成影响的CFD模拟与实验研究

摘要 本文通过数值和实验研究了从受壁面影响的非球形颗粒到湍流气流的热传递。在数值部分，使用三维有限元方法使用 FEMLAB 2.3 版求解偏方程。在实验部分，检查了管径比 (N) 范围在 4.5-6.7 之间的单个萘颗粒上的轴向流动，并通过传热和传质类比计算了努塞尔数。详细测试了管壁、颗粒形状和颗粒旋转角度对热区形成的影响。结果表明，当每颗粒直径的颗粒-管壁距离大于0.143（yc/Dp ≥ 0.143）时，可以忽略壁效应。内孔在减少热区方面没有发挥重要作用，尽管它们增加了每单位体积颗粒的传热率并由于填充床的较高孔隙率而降低了压降。当颗粒切向地靠在壁上时，在零轴向旋转角处观察到三叶颗粒的最小热区。预测结果与实验结果非常吻合。本研究的结果可用于发现更多的热点，并为填充床反应器获得更好的催化剂颗粒。当颗粒切向地靠在壁上时，在零轴向旋转角处观察到三叶颗粒的最小热区。预测结果与实验结果非常吻合。本研究的结果可用于发现更多的热点，并为填充床反应器获得更好的催化剂颗粒。当颗粒切向地靠在壁上时，在零轴向旋转角处观察到三叶颗粒的最小热区。预测结果与实验结果非常吻合。本研究的结果可用于发现更多的热点，并为填充床反应器获得更好的催化剂颗粒。