Wall-to-liquid mass transfer in fixed beds at low flow rates

The wall-to-fluid mass transfer coefficient was obtained from coated wall dissolution experiments, for water flow through fixed beds of spheres with tube-to-particle diameter ratios of 2.9-11.6, and for particle Reynolds number (Re) in the range 3-200. The coefficients, in the form of dimensionless Sherwood numbers (Sh_wf), were shown to approach a nonzero limit as Re→0. The data were well-represented by the equation