Thermodynamic and thermoeconomic modeling of humidification-dehumidification desalination systems with bubble column dehumidifier

Abstract

Humidification-dehumidification (HDH) desalination systems are popular among researchers due to their simple structure, ability to operate with low-grade and renewable energy sources, and the capacity to work with high-concentration water. This paper presents a thermodynamic and thermoeconomic analysis of an HDH system with a multi-stage bubble column dehumidifier. There was a lack of economic studies on bubble column dehumidifier systems in previous literature; also, no research had examined the impact of different geometric and temperature parameters on the entire system's performance. The fixed surface method was used to model the humidifier and dehumidifier, and the effect of mass flow rate ratio, top and bottom temperature, pipe length within each dehumidification stage, and the number of dehumidifier stages on the system's performance was studied. System performance was compared under various conditions, including gain output ratio (GOR), water production, and cost of produced freshwater. The highest GOR is obtained in the highest pipe length and the highest number of dehumidifier stages. Increasing the length of the pipe and the number of dehumidification stages increases the cost, so achieving the lowest cost of produced water is a compromise between higher cost and higher efficiency. The system achieved a GOR of 3.03, the lowest cost price of produced water is 18.29 $m3, and the highest acheived exergy efficiency is 22.4 %.