An idea that improves the wettability over the surfaces of a cylindrical dehumidifier channel was proposed and experimentally proved. Fibrous sheets were attached to the inner surfaces of the channel. The capillary effect of fibers sustains the complete wetting of the heat and mass transfer surfaces. The air to be dehumidified and cooled flows upward in the annulus space between the two layers of fibrous sheets, which are saturated with the downward flowing desiccant solution. The permeability of the fibrous sheet was determined experimentally. It was 2.43 x 10(-10) m(2). The measured solution flow rate due to the capillary suction of the sheets was Gamma(in,min) = 1.12 kg/h m. The liquid desiccant tested was H(2)O/CaCl(2) with salt concentration ratios ranging from 35 to 40%. The measured distribution of the solution flow rate along the circumference of the sheets at the outlet showed 5% deviation from the average flow rate. This is a good indication for the good wettability of walls inside the dehumidifier. Feeding the solution by this mechanism has many advantages over spray feeding. Beside sustaining complete surface wetting, it also prevents channel blockage with solution, which is a main factor in increasing the air pressure drop. About 95% of the air pressure drop is saved in this study by avoiding these problems. A simple theoretical model for the heat and mass transfer processes inside the dehumidifier was developed and experimentally validated. In general, there is good agreement between the predicted and measured data. The developed model was utilized to study the effect of the different parameters on the dehumidifier performance. For a I m height dehumidifier with an inlet specific humidity and air temperature of 0.0234 kg(v)/kg(a), and 35 degrees C, respectively, the predicted outlet air specific humidity was 0.0102 kg(v)/kg(k) and the corresponding outlet air temperature was 27.4 degrees C. The inlet solution temperature and salt concentration were 25 degrees C and 40%, respectively. (C) 2009 Elsevier Ltd. All rights reserved.