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首页> 外文期刊>International Journal of Heat and Mass Transfer >Influence of flow guiding conduit on pressure drop and convective heat transfer in packed beds
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Influence of flow guiding conduit on pressure drop and convective heat transfer in packed beds

机译：导流管对填料床中压降和对流传热的影响

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Packed beds with large tube-to-particle diameter ratios (D/d) suffer from poor lateral heat transport. Consequently, for applications with internal heat generation, fluid with high temperature concentrates in the center of packed beds, which is unfavorable to the design of high efficiency reactors. To address this problem, a novel method is developed: a free channel-flow guiding conduit (FGC)-is constructed in the center of a packed bed using highly fluid-penetrable material. Therefore, in the presented work, CFD simulations are carried out to study the influences of FGC to a conventional packed bed on packing structure, fluid flow distribution as well as heat transfer. It shows that cold fluid with high velocities is guided directly into the original hot zones where fluid temperature is generally higher in a conventional packing. Fluid flow in the lateral direction can be promoted with the Venturi effect. Moreover, with the FGC in proper sizes, pressure drop can be reduced about 16-26%; heat transfer coefficients merely drop 4-6%. However, although favorable effects could be achieved using the FGC, it is also observed that if an oversized flow guiding conduit was imposed into a packed bed, loss of effective cooling for particles would be also resulted since excess fluid could bypass through the conduit. Consequently, unexpected fluid temperature distribution could get some recovery. These findings are helpful for understanding of transport phenomena in packed beds as well as the design of high efficiency reactors. (C) 2019 Elsevier Ltd. All rights reserved.
机译：管与颗粒直径之比大（D / d）的填充床的横向传热差。因此，对于内部产生热量的应用，高温流体会集中在填充床的中央，这不利于高效反应器的设计。为了解决这个问题，开发了一种新颖的方法：使用高度可渗透流体的材料在填充床的中心构造一条自由通道导流管道（FGC）。因此，在目前的工作中，进行了CFD模拟以研究FGC对常规填料床的影响，该填料床对填料结构，流体流动分布以及传热都有影响。它表明，具有高速的冷流体被直接引导到原始的热区中，在常规的填料中，流体的温度通常较高。文丘里效应可促进横向流体的流动。此外，通过使用适当尺寸的FGC，可以将压降降低约16％至26％。传热系数仅下降4-6％。但是，尽管使用FGC可以达到有利的效果，但是还可以观察到，如果将超大尺寸的导流管道插入填充床中，由于多余的流体可能会通过管道旁通，因此也会导致颗粒的有效冷却损失。因此，意外的流体温度分布可能会有所恢复。这些发现有助于理解填充床中的运输现象以及高效反应器的设计。 （C）2019 Elsevier Ltd.保留所有权利。

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