Outdoor Testing of Double Slope Condensation Surface for Extraction of Water from Air

Abstract

In this study, extraction of water from air using double slope condensation surface is investigated. Solar energy as a heat source and Calcium Chloride (CaCl₂) as the desiccant are used. The experimental apparatus involves two parts. The first part, which functions as an absorber has nine channels containing a mixture of Calcium Chloride (CaCl₂) and sand while the second part, which functions as a transparent and condensation surface has a prism shape. At night, the absorber is exposed to atmospheric air where Calcium Chloride (CaCl₂) absorbs moisture from the air. At sunrise, the absorber is covered tightly with the transparent and condensation surface that allows the passage of the sun rays to absorber. Condensate water is collected in sloping channels that are fixed at the bottom inner surface of the transparent surface. The temperature of the transparent surface, air-vapor mixture and absorber surface, solar radiation intensity and amount of collected water are recorded during the experiments per hour for the left and right sides of the apparatus at various operating days. Experimental measurements indicate that the condensed water productivity changes with ambient conditions. It is found that the maximum productivity yield for July 31st was 825 g/day for accumulative solar radiation about 441 kW/m² day. A mathematical model is developed to calculate theoretical solar radiation intensity and amount of collected water. Its results are compared with the experimental data and a reasonable agreement between theoretical results and experimental measurements is achieved.