Convection heat transfer in a large rectangular packed duct with asymmetric heating

Experimental and numerical study of wall-to-air forced convection has been presented for a large rectangular packed duct. The horizontally oriented duct has 160 cm heated length, 40 cm width, and bed equivalent diameter to particle diameter ratio, d_c/d_p, range of 4. 5-7. 5 The separation distance, H, between the top and bottom walls is 10 cm. A uniform heat flux is supplied on the top wall, while the other walls are adiabatic. The Raschig rings in two and spherical packing in three sizes have been used in the air flow passage to study the size and shape effects, and the enhancement of heat transfer due to packing. Temperature profiles at steady state have been measured for the Reynolds number, Re_p, range of 200 < Re_p <1400. The quasi-homogeneous, two-dimensional model with an average void fraction is used together with the Ergun equation in the numerical analysis. The predictions are satisfactory for the core region of the bed. It has been found that the introduction of the packing into the air flow passage increases the wall-to-fluid heat transfer approximately three times compared with that of empty bed. The effect of the packing shape is marginal for the geometry and flow conditions considered.