A review of recent work on transient stagewise mass transfer processes is presented, with particular emphasis on numerical and analog solutions for the partial differential difference equations involved. The numerical or analog solutions are relatively simple, whereas the analytical solution even of the linearized equation is quite involved.
An example of gas absorption is considered in which the equations are linearized, and solved numerically as well as by the use of a resistance network analog. These particular methods of solution had not previously been used for this problem, and the present work is compared with previous solutions. The novel feature of the method of solution is the representation of the time derivative by a backward finite difference to produce a set of simultaneous algebraic equations, which may be solved most easily by matrix inversion programmed on a digital computer.