Operational analysis of a humidification-dehumidification desalination in packed bed humidifier and dehumidifier columns with salt- and freshwater recirculation

Desalination technologies are increasingly being developed to improve the environmental aspects, performance, and availability. In this study, a new configurated humidification-dehumidification desalination device, that uses a direct contact condenser, has been experimentally investigated. The device includes humidifier and dehumidifier, saltwater heating and freshwater cooling systems, fresh- and saltwater pumps, and tanks. Energy and mass recovery are some of the features of the device. Humidifier and dehumidifier performance at various operating conditions was studied. The proposed HDH structure consists of two similar packing towers, each tower having the same diameter of 25 cm, and a height of 1.5 m, which is filled with rushing packing. Operating parameters include saltwater recirculation rates in the humidifier (3.3, 6, and 12 L/min), freshwater recirculation rates in the dehumidifier (2.3, 5.6, and 8.5 L/min), the airflow rate (from 128 until 236 m3/h), and the temperature of each stream on the performance of the humidifier and dehumidifier which have been studied experimentally. The results show that the direct contact condenser can reach up to an effectiveness of 0.7. The condenser performance coefficient increases, when the ratio of freshwater flow rate to airflow rate increases. The best performance of the device is in mass ratios higher than 1.9. The freshwater produced in this system will be up to 312 L/day. This portable device can supply the daily consumption of a household in remote, coastal, and island regions that do not have access to freshwater.

Automated summary

This study investigates a new configurated humidification-dehumidification desalination device that uses a direct contact condenser. The performance of the humidifier and dehumidifier under various operating conditions was experimentally studied. The results show that this device can produce up to 312 L/day of freshwater, making it a viable water supply option for households in remote areas without access to freshwater.