Experimental study of forced convective heat transfer in grille-particle composite packed beds

Due to high surface area-to-volume ratio and superior thermal performance, packed beds are widely used in variety of industries. In the present study, forced convective heat transfer in a novel grille-particle composite packing (GPCP) bed, was experimentally investigated in pursuit of reduced pressure drop and enhanced overall heat transfer. The effects of sub-channel to particle diameter ratio, grille thickness and grille thermal conductivity on pressure drop, Nusselt number and overall heat transfer efficiency in the grille-particle channel were carefully analyzed. And performances of grille-particle channels were compared with those of random particle channels in detail. It is shown that looser packing structure compromises heat transfer in the grille-particle channel, while decreasing pressure drop and improving overall heat transfer efficiency. Meanwhile, for the same Reynolds number and particle diameter, higher grille thermal conductivity and thinner grille thickness also improve overall heat transfer performance. Finally, when compared with random packing, both pressure drop and heat transfer in grille-particle channels are shown to be reduced, while overall heat transfer efficiency is improved, especially when employing relatively small particle diameters. (C) 2018 Elsevier Ltd. All rights reserved.