Influence of position on the natural and forced convective heat transfer of a single heating sphere in a packed bed

Abstract

Natural and forced convection experiments on a single heating sphere in a packed bed were performed by varying the axial and radial positions of the heating sphere. Based on the analogy between heat and mass transfer, mass transfer experiments were conducted using a copper electroplating system. The sphere diameter was varied from 0.004 to 0.010 m, which correspond to the Rad of 5.43 × 106–8.48 × 107. The Sc was 2,014. In the forced convection experiments, the range of superficial velocity was 0.01 to 0.58 m/s, which correspond the Red of 43–5,076. For natural convective flow, the influence of sphere position on the heat transfer of single heating sphere in the packed bed was not observed. However, for forced convective flow, the local heat transfer inside the bed was affected by the variation of the sphere position. The heat transfer increased at the downstream layer of bed due to the intensified turbulence level by the porous structure. The heat transfer near wall region was also enhanced due to the high local porosity. Based on the experimental results, we developed the correlation of local heat transfer for forced convection by adding the multiplier to the existing correlation.