The Impact of a Balanced Humidification-Dehumidification Desalination System Driven by a Vapor-Compression Heat-Pump System

Abstract

This study examines a novel desalination system by conducting thermodynamic and economic analysis. The system consists of a humidification-dehumidification (HDH) desalination unit powered by a vapor compression (VC) heat pump. The HDH unit applies the thermodynamic-balancing method with multiple extractions. The performance of the proposed VC-HDH system is evaluated for water production under specific operating conditions. The experimental validation of the system model is also conducted. The results show that without air extraction, the system can produce 6.62 kg/h of desalinated water at a cost of 0.011 $/l with a gained-output-ratio (GOR) value of 9.1. When single air extraction is applied, the system produces about 20 l/h of desalination water at 29 GOR for 0.0042 $/l. Increasing the number of air extractions to two results in a freshwater production rate of approximately 40 kg/h at a cost of 0.0026 $/l and a GOR of 57. A considerable positive effect of the HDH unit’s performance is found on both the thermos-economic performance of the investigated system. For better desalination performance, it is also found that the feed water temperature should be maintained between 25 and 30°C. Finally, the theoretical maximum GOR of the system is estimated.

Keywords: air extraction, Desalination, Humidification-dehumidification, balancing, Vapor compression