A novel solar-driven vacuum desalination unit: Simultaneously venturi-induced self-evaporation and self-condensation withfresh water cycle

Abstract

Integrating solar energy in desalination processes offers a cost-effective and efficient solution. Moreover, reducing the saturated temperature of water vapor through pressure reduction can lower energy consumption and improve evaporation rates. This study investigates the performance of a novel venturi system integrated with an evacuated tube collector (ETC) that simultaneously conducts low-pressure evaporation and condensation. The research evaluates the system’s response to variations in flow rate and explores the potential for reducing freshwater pump activity to conserve energy. Increasing the flow rate led to a greater pressure differential across the venturi, causing a decrease in throat pressure. The system achieves its peak water production at a flow rate of 75 L per minute (LPM), yielding 9.02 kg/m2 with a system pressure of 0.297 bar. This production signifies a notable surge of 37.01 % compared to the recorded minimum flow rate. The cost analysis indicates that the cost of producing one kilogram of water per unit area is $0.045. The system achieved its maximum efficiency of 40.87 % by decreasing the water pump operation time to 1.5 h/day while following a cycling pattern of 5 min on-15 min off.