Mass transfer from fluid and solid spheres at low reynolds numbers

Predicted continuous phase mass transfer coefficients for fluid and solid spheres in the Stokes region of flow are correlated as Sherwood numbers plotted against Peclet numbers. These correlations permit a study of the effect of internal circulation on the rate of mass transfer from fluid spheres. At a Peclet number of 10 4 , the theory predicts a threefold increase in transfer due to the circulation movements within a gas bubble. At a Peclet number below 10 −2 , the difference between a circulating and non‐circulating (or solid) sphere is indiscernible. The analysis presented in this paper for fluid spheres is based on a study by Friedlander (1) of mass transfer around solid spheres. A more elaborate concentration profile through the boundary layer has been used in the present investigation and the result reported for solid spheres differs about 8% from that given by Friedlander. The more interesting details of the mathematical treatment and the machine computation of the resulting differential equations are included.