Simplified models for coupled heat and mass transfer in falling-film absorbers

A linearized coupled model is developed for the heat and mass transfer in falling-film absorbers. Its accuracy is established by comparing the predictions with those of a non-linear model and a numerical simulation. Under certain conditions, the linearized model reduces to the log-mean-difference formulation. The linearized model yields analytical expressions that are used to determine heat and mass transfer coefficients from the experimental data for a horizontal tubular absorber and a vertical tube absorber. The overall Nusselt number and Sherwood number for the tubular absorber increase with increasing film Reynolds number and inlet cooling water temperature. The cooling water temperature distribution predicted by the linearized model agrees well with measurements.