Performance analysis of a solar desalination system operated by humidification-dehumidification technique

The humidification-dehumidification desalination system represents a thermal-based technology primarily intended for small-scale water desalination applications. It facilitates the production of distilled water from saline seawater at sub-boiling temperatures by employing low-grade heat sources, such as solar energy or waste heat, which are both readily available and characterized by low operational costs. This study aims to enhance the yield of distilled water from actual seawater (Suez Canal water) while simultaneously reducing production costs under the climatic conditions of Cairo, Egypt. To achieve this, an experimental, economic, and environmental evaluation was conducted on a closed-air open-water humidification-dehumidification desalination system, which is recognized for its superior energy efficiency. The pilot plant was constructed, and experimental trials were performed during the months of February and March. The investigation focused on assessing the effects of varying the seawater mass flow rate for a range of 0.39-0.63 kg/s and the air velocity during daytime operation hours. A constant flow of city water was supplied to the dehumidifier coil to condense the water vapor from the moist air. System performance was monitored from 9 AM to 5 PM daily. The findings indicate that the maximum distilled water production reached 17.04 kg/day at a seawater flow rate of 0.63 kg/s and an air velocity of 13.2 m/s. The estimated cost of distilled water production was approximately 0.017 $ per liter, while the CO₂ emission was reduced by 6 tons annually for the same amount of distilled water.