(567e) Modeling of Absorption with Reversible Reactions with Nonlinear Kinetics

Design calculations based on mathematical models of absorption with chemical reaction require computationally efficient, accurate and robust algorithms. This is particularly challenging when there are multiple reversible reactions with nonlinear kinetics and disparate time scales. Approximate analytical techniques solutions have been developed for solving the governing ordinary differential equations (ODEs) in the context of steady-state film theory, One, based on an analysis developed by K.A. Smith, linearizes the ODEs based on the assumption of small perturbations from local reaction equilibrium states. It yields asymptotically exact absorption rate predictions when the reactions are very fast. The other, originally developed by Van Krevelen and Hoftijzer, does so based on the assumption that, in the kinetic expressions, the concentrations of nonvolatile reactive solutes may be fixed at their values at the gas-liquid interface. It yields asymptotically valid absorption rates in the limit of very slow reactions. Surprisingly, both approaches are generally quite accurate over wide ranges of the Hatta numbers. However, there are regimes where this is no longer true and numerical methods of solutions are required. The latter are the focus of this presentation.