Experimental investigation of a solar vacuum humidification-dehumidification (VHDH) desalination system

A solar desalination system using the HDH technology with sub-atmospheric pressures inside the humidifier has been experimentally investigated in this study. The influence of inlet water and air temperatures, the absolute humidity of the air, and the ratio of the mass flow rate of water to that of air in the humidifier on the rate of desalinated water production, and gained output ratio (GOR) have been studied. The developed set-up includes a humidifier, a liquid ring vacuum pump, solar air and water heaters, and a double-pipe condenser. The optimum values for the main parameters were determined by the response surface methodology (RSM). The results indicate that the reducing the humidifier pressure has benefits, and intensifies the effects of the other parameters on the production rate of the desalinated water. In this operating condition, the desalinated water production reached a rate of 1.07 L/h·m2, and the maximum GOR was 3.43. To complete a comprehensive study of the proposed plant, a cost evaluation of the developed system has been done.