Heat and mass transfer between air and falling desiccant film is investigated for inclined parallel and counter flow configurations. Two different configurations are proposed and parametrically analyzed. Effect of inclination angle is examined to study enhancements in dehumidification and cooling processes of the air and regeneration of liquid desiccant in terms of pertinent parameters. Cu-ultrafine particles are also added to the desiccant film to investigate the enhancement in heat and mass transfer between the air and the desiccant film. The pertinent parameters are air and desiccant Reynolds numbers, inlet conditions for both air and liquid desiccant, Cu-ultrafine particles volume fraction, and thermal dispersion. It is shown that inclination angle plays a significant role in enhancing the dehumidification, cooling, and regeneration processes. (C) 2003 Elsevier Ltd. All rights reserved.