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

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.