A model for a horizontal tube absorber using LiBr/water as the working fluid was developed to predict heat and mass transfer in falling-film and droplet mode flow. In the analysis the effect of incomplete wetting is considered by introducing the wetting ratio. To validate the developed model a series of calculations is carried out under the same conditions as in experiments performed by other investigators. The simulation results for temperature, concentration variations, and heat and mass transfer rates are presented and compared with these experimental data. The effects of wetting ratio and solution flow rate on cooling capacity are discussed in detail.