A humidification-dehumidification (HD) solar desalination unit was designed. It seems to be suitable to provide drinking water for population or remote arid areas. Solar water and solar air collectors were designed to provide the hot water and air to the desalination chamber. The desalination chamber was divided into humidifier and dehumidifier towers. The circulation of air in the two towers was maintained by the forced convection. Theoretical and experimental works were done at different environmental conditions. A mathematical model was formulated, in which the thermodynamic relations were used to study the flow, heat and mass transfer inside the humidifier and dehumidifier. Such a technique was performed in order to increase the unit performance. Heat and mass balance was done and a set of governing equations was solved using the finite difference technique. The solar intensity was measured along the working day during the summer and winter months and a comparison between the theoretical and experimental results were performed. The average accumulative productivity of the system in November, December and January was ranged between 2 to 3.5 kg / m 2 day while the average summer productivity was found between 6 to 8 kg/m 2 day in June and 7.26 to 11 kg/m 2 day in July and August. 2 ‫الفصل‬ ‫نفس‬ ‫من‬ ‫وأغسطس‬ ‫يوليه‬ ‫شھور‬ ‫ل‬ ‫خ‬ .

The current research experimentally investigated a sustainable desalination method to maximize freshwater production at minimal costs. Solar photovoltaics are used as a source of clean and renewable energy. The system used in conducting the experiments consists of: an air heater, water heater, two stages of cross-flow humidification, two stages of cross-flow dehumidification, and an oxyhydrogen gas generator. The setup's working principle is the open-air and closed water cycle. A centrifugal fan blows the ambient air to pass through the air heater. Air is heated through a heat exchanger, which is consequently heated by hot water. Water is heated using a new heating approach by using a mixture of 20% natural gas and 80% hydrogen gas with less impact on environmental pollution. Air is then humidified through two-stage humidification systems using a high water temperature technique, then through the innovative vibrating plate circuit, respectively. The humidified air is condensed through two consecutive dehumidification heat exchangers. The system parameters are optimized to enhance freshwater productivity. The studied operative parameters are air mass flow rate, water mass ratio (WMR), and the effect of adding a second stage of humidification. The results showed that the maximum daily productivity is 49.3 kg/day. The optimum air mass flow rate and water mass ratio to obtain maximum productivity was found to be 0.375 kg/s and 0.6, respectively. Furthermore, the experiments' results showed that two-stage humidification enhanced freshwater productivity by 23.25% than that of the single stage of humidification. Finally, an economical study analysis conducted for the test rig showed the cost per liter to be 0.