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Water and energy are two inseparable issues that play an important role in human life. The oceans are massive resources of water, but the main problem is their high salinity. Solar desalination systems have been considered as a suitable solution to solve the problem of water deficit and to overcome the environmental problems caused by the conventional water desalination plants. One of the important points in raising the efficiency of solar water desalination systems is increasing the evaporation rate in a system with specified dimensions. The direction of the spraying of seawater in the chamber is one of the effective parameters in elevating the discharged rate of vapor in solar desalination systems. In this study, the effects of other parameters including injection pressure, nozzle outlet diameter, nozzle type, and relative humidity inside the chamber were investigated in both upward and downward injection directions by a mathematical model. The results of the model indicated variations in the rate of vapor generation in upward and downward directions. Also, the effects of other important parameters were studied including injection pressure (in the range of 1 to 5 bar), outlet diameter of the nozzle (in the range of 0.9 to 1.1 mm), type of nozzle (long cone orifice, drilled steel orifice, and sapphire orifice) and relative humidity (within the range of 20% to 60%). Overall, the results indicated increased vapor production at an injection pressure of 5 bar, nozzle outlet diameter of 0.9 mm, long cone orifice nozzle, a relative humidity of 20%, and upward direction. [ABSTRACT FROM AUTHOR]

Water plays a significant role in the daily activities of the human population, and its overall consumption is increasing rapidly, due to the enhancement of living standards. Iran is located in the dry belt of the earth, and 70% of its area is arid and semi-arid. The desalination systems, which use fossil fuels in order to overcome the water crisis in Iran, are not ever sustainable due to available energy depletion and greenhouse gas emissions. This study investigated the design of an active solar water desalination system. Evaporation rate and diameter reduction of sprayed saline water droplets in a glass chamber were calculated by a verified mathematical model. The effect of key parameters, including nozzle type (long cone orifice, drilled steel orifice, sapphire orifice), nozzle size (outlet diameters of 0.9–1.1 mm), injection pressure (1–5 bar), temperature, relative humidity (20–60%) and pressure inside the glass chamber (4500–6500 Pa), on evaporation rates, were investigated by the mathematical model. The flow rates of produced vapor and inlet saline water were calculated as 0.003252 L/s and 0.0181 L/s, respectively, by considering favorable condition, such as injection pressure of 5 bar, nozzle size of 0.9 mm, relative humidity of 20% and pressure of 4500 Pa inside the glass chamber. Radiation intensity was calculated using Meteonorm 7 software for Tehran during a year, which was compared with meteorological data of Mehrabad airport station. [ABSTRACT FROM AUTHOR]

In this study, the evaporation of injected water droplets, as one of the most important parts of the solar desalination system, was investigated. Elevating the evaporation rate is considered as one of the important points in increasing the efficiency of solar water desalination systems. The effective parameters on evaporation rate and reduction of the droplets’ diameter, which were sprayed in the chamber were investigated using the mathematical model. It should be noted that the effects of different factors mean environmental conditions inside the chamber, such as relative humidity and pressure, as well as the primary conditions of the droplet, including temperature, injection pressure, and initial diameter, were also considered. In this study, the information about a droplet inside the glass chamber in a downward direction at injection pressures of 1, 3 and 5 bar, inlet temperatures of 60°C, 65°C and 70°C and nozzle outlet diameters of 1.1, 1.0 and 0.9 mm was investigated by considering three types of long cone orifice, drilled steel orifice and sapphire orifice nozzle at different relative humidity and pressure values in a glass chamber to determine the favorable conditions for evaporation of saline water and freshwater production. Increasing the availability of freshwater by producing a high-flow rate of vapor is known as the most important achievement in solar water desalination systems. Finally, the best condition for producing freshwater was obtained at the injection pressure of 5 bar, the inlet temperature of 70°C, and the nozzle outlet diameter of 0.9 mm with a discharge coefficient of 0.9. [ABSTRACT FROM AUTHOR]

In this research, an active combinational solar water desalination system was designed and investigated. Sea water was guided towards a solar collector and was evaporated in a glass chamber where the produced vapor was conducted towards a water cooled condenser using a compressor, thereby resulting in the production of distilled water. In the first experiment, the corrosion test was performed to investigate the occurrence of corrosion in the solar collector and the floor of the glass chamber. According to the corrosion test performed in the first experiment, the corrosion rate of copper, the galvanized sheet, and stainless steel was measured to be 21.874, 24.356, and 17.595 mm/year, respectively. In order to reduce corrosion in the system, a descaling solution (acetic acid) was used, where the results of the corrosion test for copper and the galvanized sheet in the presence of the descaling solution were measured to be 14.759 and 14.795 mm/year, respectively. Considering the closeness of the corrosion rate of the galvanized sheet and the stainless steel sheet, as well as the finished price of the sheet employed in the floor of the glass chamber, the application of the galvanized sheet is more economical than the use of the stainless steel sheet. [ABSTRACT FROM AUTHOR]