Studies on heat transfer near wall surface in packed beds

From studies of annular packed beds wherein the heat flows purely radially, the authors obtained the coefficients of heat transfer on the inner tube surface, as well as the mean effective thermal conductivities of bed. The inner and outer diameters of the annular packed bed were 22 and 70 mm. respectively, and the packings shown in Table 1 were used. The wall film coefficients obtained with air flowing axially through the bed were correlated for NReM < 600 by means of Equation (14). The coefficients of heat transfer for cylindrical packed beds reported previously by other observers were correlated also by Equation (14), with 0.054 used for values of αω in the range NReM < 2,000. Consideration of Equation (14) in terms of a theoretical model of heat transfer showed that it was reasonable to apply it for the prediction of wall film coefficient, especially for low Reynolds numbers.