A comprehensive mathematical model has been developed for the simulation of simultaneous chemical absorption of carbon dioxide and hydrogen sulfide by means of Monoethanolamine (MEA) aqueous solution in hollow fiber membrane reactors is described. In this regard, a perfect model considering the entrance regions of momentum, energy, and mass transfers was developed. Computational Fluid Dynamics (CFD) techniques were applied to solve governing equations, and the model predictions were validated against experimental data reported in the literature and excellent agreement was found. Effects of different disturbances on the dynamic behavior of the reactor were investigated. Moreover, effects of various parameters such as wetting fraction, gas and liquid inlet velocities, inlet temperature of the solvent, MEA concentration, and CO 2 and H 2 S compositions were carefully studied. It was found that for large values of gas velocity or small values of liquid velocity, the thermal energy equation can play an important role in the model predictions. MEA concentration 5 0.5 M, gas flow rate 5 1000 mL/ min, and liquid flow rate 5 25 mL/min. Inlet liquid velocity 5 0.0503 m/s, inlet liquid temperature 5 308 K, inlet gas pressure 5 100 kPa, gas feed: 0.14 CO 2 , and MEA concentration 5 1.0 M. Inlet liquid velocity 5 1.0 m/s, inlet liquid temperature 5 308 K, inlet gas pressure 5 100 kPa, gas feed: 0.15 CO 2 and 0.05 H 2 S, MEA concentration 5 1.0 molar, wetting fraction 5 0.1, and inlet gas velocity 5 2.0 m/s. AIChE Journal February 2014 Vol. 60, No. 2 Published on behalf of the AIChE Inlet liquid velocity 5 1.0 m/s, inlet liquid temperature 5 308 K, inlet gas pressure 5 100 kPa, gas feed: 0.15 CO 2 and 0.05 H 2 S, MEA concentration 5 1.0 molar, and wetting fraction 5 0.1. 668

A comprehensive mathematical model has been developed to analyze transport phenomena in wetted wall absorption reactors. In this regard, a wetted wall reactor was modelled considering the entrance regions of momentum, heat and mass transfer, compressibility of the gas phase as a function of gas temperature, pressure, and composition, and also non‐Newtonian behaviour of the liquid phase. In the developed model, a gas mixture of two components, A and B, was considered as the gas phase (A as the diffusing component), while a binary liquid mixture of components C and D was taken as the liquid phase (C as the reactant component). CFD methods were applied to solve nonlinear governing equations simultaneously and the simulation results were validated against experimental data reported in the literature and excellent agreement was found. Moreover, distributions of velocity, temperature, and species concentrations of both phases were obtained and the effects of various operating conditions and physicochemical properties on these distributions were carefully studied. Furthermore, the open‐loop response of the reactor to some typical step and pulse inputs was examined. Moreover, the closed‐loop response of the reactor was also examined; in this regard, a PI controller was designed to control the reactor's output properly.

In this article, a comprehensive model has been developed for analyzing the transport phenomena in hollow fibre membrane contactors operated under non‐wetted or partially wetted conditions. In this regard, the dynamic behaviour of membrane contactors, considering the entrance regions of momentum, thermal energy, and mass transfers, was investigated carefully. Moreover, effects of temperature distribution on the contactor efficiency were examined by taking into account the influences of heat of solution, heat of reaction, and the viscous dissipation. The chemical system studied was a gas sweetening process, including methane and carbon dioxide as the gaseous mixture, and MEA aqueous solution as the solvent. CFD techniques have been used to solve the nonlinear governing equations simultaneously, and the model predictions were validated against reported experimental data in the literature, and excellent agreement was found. Comparing the model predictions with those of previous models shows relatively better accuracy of the model predictions. Furthermore, distributions of velocity, temperature, and species concentrations in the tube side, shell side, and the membrane were obtained and the effects of various operating and design parameters such as wetting fraction, gas and liquid inlet velocities, inlet temperature of the solvent, MEA concentration, and CO2 volume fraction of the feed on these distributions were carefully studied. Finally, the dynamic response of the system was investigated by analyzing the contactor's response to different step and pulse changes.