Abstract
A solar powered desalination unit which working on a humidifiation –dehumidifiation technique (HDH) is one of the most important techniques used in brackish and seawater desalination especially in remote and rural areas. In the present study, a test-rig was designed and constructed for conducting a set of experiments on a solar assisted desalination unit working on a HDH principle under the prevailing conditions of Tajoura-Libya. Experiments were carried out on specifid days in March, 2019 at the laboratories of Center for Solar Energy Research and Studies (CSERS) at Tajoura. Th effct of diffrent design parameters and operating conditions on the performance of the unit and its productivity is closely investigated and interpreted. Results show that the productivity of the HDH unit decreases by increasing the process air mass flw rate. A signifiant improvement in the productivity of the unit is noticed when the feed water mass flw rate to the humidifir is increased. Furthermore, initial water temperature inside the tank has a remarked effct on the productivity of the unit. In order to obtain a reasonable amount of fresh water, the temperature of the water inside the tank should be increased. Increasing the cooling water mass flw rate to the dehumidifir leads to a corresponding decrease in the surface temperature of the cooling coil and hence the productivity of the unit is improved. Th Productivity of the unit is varying from its lower value of (0.903 kg/m2.day) to a higher value of (6.47 kg/m2.day). Thse values are obtained for one meter square of solar air heater area. Gained Output Ratio (GOR) values range from a minimum of (0.082) to a maximum of (0.572). It is reasonable when compared to ones in literature for the water-heated HDH units.

Key words: Solar, desalination, humidifiation, dehumidifiation, productivity