Transient physical gas absorption in a stirred liquid using the surface renewal model of mass transfer

This work presents a rigorous surface renewal model for unsteady-state physical gas absorption in a stirred batch cell in which the concentration of dissolved gas in the bulk liquid is a function of time for zero and finite gas-phase mass-transfer resistance. Using experimental parameters from the literature for oxygen and hydrogen absorption in water at 25 degrees C and atmospheric pressure, predictions of the model reveal that the rates of absorption and dissolved-gas transfer to the bulk liquid exhibit an inverse behavior during the initial moments of absorption after which they merge into a single curve and decline with process time as the water becomes increasingly saturated with the dissolved gas. Predictions for the dissolved oxygen concentration made with the rigorous model compare excellently with those of the standard pseudo steady-state model used in the literature except for short time scales. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study introduces a rigorous surface renewal model for analyzing unsteady-state gas absorption in a stirred batch reactor. The predictions of the model show that absorption rate and dissolved gas transfer rate exhibit an inverse behavior initially, but then merge and decrease over time as the saturation of dissolved gas increases in the water.