Mass transfer from fluid and solid spheres at low Reynolds numbers: Part II

Rates of mass transfer from water drops into cyclohexanol and from drops of cyclohexanol, isobutanol, and o‐toluidine into water were measured. These experimental data were augmented by published results, to cover, at drop Reynolds numbers less than 10, a Peelet number range of 0.01 to 5,000,000 for non‐circulating spheres and 700 to 24,000,000 for circulating spheres. Transfer rates, expressed as Sherwood numbers, were in substantial agreement with those predicted from a theoretical model. The contribution of natural convection, inherent in the measurements, but omitted in the model, was approximately accounted for. Data for circulating spheres verified the hypothesis that internal motion affects the external transfer rate. This effect depends on the ratio of continuous to disperse phase viscosity of the system; a four to six‐fold enhancement of mass transfer due to internal circulation was found for water drops falling in cyclohexanol.