Gas absorption in packed columns was modelled, taking into account all heat effects for phys. gas absorption. Multicomponent diffusion effects were incorporated in terms of the film-factor concept. An algorithm of very stable convergence behavior was obtained by simulating the start-up procedure of the column dynamically in order to evaluate the steady-state operation. The importance of rigorous design calcns. was assessed by comparing the rigorous soln. with simplified hand calcns. for a large no. of cases. If the solvent is volatile, it appears impossible to est. the highly irregular temp. profiles by hand and to design the column approx. by simplified calcns. based on neglecting one or more of the heat effects. Simplifying assumptions also are unsuitable to obtain a limiting conservative design. [on SciFinder (R)]