Gas absorption with interfacial resistance in the case of temperature‐dependent physical, transport and reaction properties

Abstract

This work analyzes the problem of interfacial resistance to heat and mass transfer for a gas absorption system with first order reaction when the solubility, the diffusivity, and the reaction rate constant are dependent upon temperature. A film theory model is applied. Two different types of temperature‐dependent solubility relationships, the linear and the exponential approximations, are employed. The temperature‐dependent diffusivity and reaction rate constant are expressed in exponential form. Three cases of different solute concentrations are compared to study the influence of solubility on the system performance. One of these cases with the exponential temperature‐dependent solubility is further examined for the effects of diffusivity coefficient and of surface resistance on the enhancement factor, the temperature rise, and the solubility. The results indicate that the form of the temperature‐dependent solubility relationship plays an important role in the estimation of the surface temperature rise and hence the enhancement factor. The linear approximation predicts slightly higher values in the intermediate region of √M_o , while the exponential approximation results in dramatically higher values at very large √M_o. The surface resistance significantly affects the absorption rate, the interfacial temperature rise, and the solubility at small values of √M_o. The effect of the variation of diffusivity on the system performance is of secondary importance, especially when the values of √M_o are not large.

Key words:

• chemical absorption
• interfacial resistance
• temperature‐dependent properties
• enhancement factor

Notes

Correspondence addressee