NONISOTHERMAL GAS-ABSORPTION WITH REVERSIBLE CHEMICAL-REACTION

A fundamental description of non-isothermal mass transfer accompanied by a single reversible chemical reaction has been presented. The descr iption is based on the Higbie penetration theory. Arrhenius type depen dence of solubility, reaction rates and diffusivities on temperature h as been assumed. Special emphasis has been paid to bimolecular irrever sible reactions where depletion of the liquid phase reactant occurs. I n addition, the mass transfer behavior in the infinite enhancement reg ime has also been presented. It has been shown that the Shah criterion fails under conditions where depletion of the liquid phase reactant o ccurs. In the infinite enhancement regime, the non-isothermal enhancem ent factor is dependent on the ratio of the diffusivities of the react ants, the ratio of the initial stoichiometric reactant concentrations and the activation energies of solubility and reactant diffusivity. Th ese characteristics of the infinite non-isothermal enhancement factor have been reported earlier by Asai et al. (1985, A.I.Ch.E. J. 31, 1304 -1312). Additionally, it has been shown that, for bimolecular irrevers ible reactions, the use of correlations for interfacial temperature ri se that assume all heat to be released at the interface is not valid f or systems with low Lewis numbers but also not for systems where deple tion of the liquid phase reactant occurs. Further, the model has been used to study the effect of reversibility on bimolecular reactions. Th e effect of temperature dependence of the solubility of the gaseous co mponent and diffusivities of the various species on the overall enhanc ement has been presented. Since the non-isothermal enhancement factor of bimolecular reversible reactions is dependent on various parameters , it is not possible to determine its value by analytical or via appro ximate techniques. One is forced to use numerical methods for this pur pose instead. (C) 1997 Elsevier Science Ltd.