Experiment and modeling of an improvised atmospheric water harvester for arid and semi-arid conditions

Abstract

Freshwater scarcity is a severe challenge in arid and semi-arid climatic conditions wherein the water harvesting from the atmosphere using active cooling condensation technique (ACC) is the only option. In this regard, we performed extensive experiments on a classical atmospheric water harvester (AWH) that relies on moisture condensation via a typical 1TR refrigeration cycle. We developed a MATLAB-SIMULINK based AWH model to note that the classical system has reasonable water harvesting rates in humid climates, but is inadequate for arid and semi-arid climatic conditions. We add an ultrasonic humidifier (160 W power input) before the evaporator section of the classical AWH system to address this issue. The modified system only needs a small amount of water (≈250 ml) for start-up, and further operates without perpetual water supply. We measure the water overflow from the humidifier tank (subtract the water added via the humidifier from the total water harvest) to show a net water harvesting in extremely hot and dry conditions (49 °C DBT and 12 % RH) resembling the weather conditions of Jaisalmer, India. A significant improvement of up to 70 % in water harvesting was also observed under warm and dry climates (35 °C DBT and 21 % RH) mimicking Jaipur, India. We believe that our system shows path for developing active AWH systems with substantial water harvesting in arid climates where active moisture condensation using the conventional strategy is otherwise not possible.