Temperature-dependent physical properties in physical gas absorption

A solution for interface temperature rise in physical gas absorption due to heat of solution was obtained by Danckwerts [1,2] with the limitation that the pertinent physical properties-diffusion coefficient, solubility of the gas and thermal conductivity of the liquid remained constant. This paper complements Danckwerts' contribution by considering the pertinent physical properties as temperature-dependent, the dependence being of the form:. Q Qi = exp [γ_Q(T - T_i)]. Wagner [3] has obtained solutions for unsteady-state diffusion when the diffusion coefficient is similarly dependent on concentration. Wagner's solutions are adapted to provide a solution for the present problem. Two approximate solutions, one valid at high Lewis Number and the other when Lewis Number approaches unity are also presented. For the normal values of activation energies, Danckwerts' model is shown to be accurate when interfacial temperature rise is less than one percent of the absolute temperature of bulk liquid. The extent of departure from the Danckwerts' model is shown to depend on combinations of activation energies of the pertinent physical properties.