In this study, heat transfer of air-water-vapour mixtures in a desalination plant, using the aero-evapo-condensation process is studied experimentally. The present process consists in a falling film evaporator and a condenser. The prototype is designed to work at low temperatures (60 degrees C-90 degrees C) using a geothermal energy. Two experimental pilots were developed. These latter, installed respectively in France and the south of Tunisia were supplied by fuel and geothermal energy. The experimental results highlighted a critical film flow rate, characterising the phenomenon of film breakdown. At this value, a maximum amount of evaporated water was obtained. Experimental results were compared with those derived from the model developed by Bourouni et al, [1] in previous investigation. From this comparison it can be learnt that the model is well able to predict the heat and mass transfer in the evaporator. This will help to optimise this component of the aero-evapo-condensation units.