ABSTRACT
This chapter presents the steady-state examples of mass transfer for binary systems in the case of no bulk flow. In the case of mass transfer of fluids through solids and/or membranes, the order of magnitude of the diffusive flux is much greater than that of the convective flux. If the measuring instrument, that is, the concentration probe, is not sensitive enough to detect concentration variations in the radial direction, then it is necessary to change the scale of the problem to match that of the measuring device. The accuracy of the measurements dictates the equation to work with since the scale of the measurements should be compatible with the scale of the equation. The effectiveness factor is the ratio of the apparent rate of conversion to the rate if the entire interior surface of the catalyst particle were uniformly exposed to the concentration.
