格栅颗粒复合堆积床内流动传热的实验研究

Experimental Study on Fluid Flow and Heat Transfer in Grille-Sphere Composite Packed Bed

颗粒有序堆积床相比于颗粒无序堆积床具有压降较小的优点,但在实际操作中,有序堆积床的实现具有一定的难度,本文设计了一种可快速实现有序堆积的新结构,即带有格栅的复合颗粒堆积结构。采用萘升华热质比拟方法对格栅颗粒复合堆积结构中的颗粒-流体对流传热系数进行了研究。结果表明,格栅复合堆积结构相比于简单立方堆积结构,压降略高,但传热系数也有大幅度提高;而相比于无序结构,在传热系数下降不多的情况下,压降大大减低。格栅颗粒复合堆积结构的综合传热系数最高,可为堆积床的设计提供一种新的思路。

Structured packed beds can have a lower pressure drop compared to randomly packed beds. However, structured packed beds are hard to achieve. In the present paper, we designed a structure that can obtain a structured packed bed more easily, that is the grille-sphere composite packed bed. The fluid flow and particle-to-fluid heat transfer characteristics are experimentally investigated by naphthalene sublimation technique and the heat-to-mass analogy. Results show that firstly, compared to the simple cubic packing, the grille-sphere composite packed bed has a slightly higher pressure drop and can improve the heat transfer at the same time. Secondly, the pressure drop of the grille-sphere composite packed bed is much lower than that of randomly packed bed, while the heat transfer decreases just a little. Finally, the grille-sphere composite packed bed has the highest overall heat transfer coefficient among three packed beds. Results of the present paper provide a new method to improve the overall heat transfer property of packed beds.