Experimental Study of Convective Heat Transfer in Grille-sphere Composite Structured Packed Bed

Randomly packed beds are widely used in practice due to their low cost and ease of use, however, the pressure drops in such packed beds are usually high. Compared with randomly packed beds, structured packed beds have a relatively lower pressure drop, while the heat transfer is weakened, and their packing form is hard to achieve. In the present paper, a grille-sphere composite structured packed bed (GSCSPB) is designed and the pressure drop together with the heat transfer in GSCSPB is experimentally investigated by using the naphthalene sublimation technique. Firstly, it is found that, the pressure drop in GSCSPB is a little higher than that of simple cubic (SC) packing and is much lower than that of randomly packed bed. Secondly, it shows that the particle-to-fluid heat transfer coefficient (h_sf) in GSCSPB would be improved by 94% of SC packing, and can be 76% of that in randomly packed bed. That shows a highest overall heat transfer performance of GSCSPB. Finally, it reveals that the grille-to-fluid heat transfer coefficient (h_gf) in GSCSPB is 1.05-1.23 times than h_sf in GSCSPB, which indicates a huge potential for the heat transfer capacity in GSCSPB.