Experimental and numerical investigation of humidification/dehumidification solar water desalination systems

In this work, a humidification-dehumidification process is considered as an advanced technique to design and construct a solar water desalination system. In this system, the salt water is heated in a solar collector before flashing inside an insulated chamber to be evaporated and condensed naturally later on where the rest of saline water is re-circulated into the system. Three systems are manufactured and tested in Cairo, 30 degrees N. The salt water is circulated in a separate loop for the first and second systems. In the first system, an auxiliary heater is used to switch the temperature of the salt water where it is naturally switched in the second system depending on the weather conditions. The third system is an open system in which the salt water is used as a collector fluid. In all three systems, a thermosyphon solar water heater is used as a heat source consisting of a collector and a storage tank. A numerical simulation was developed for the considered systems to predict their annual performance and desalinated water production. An agreement between the measured and simulated data was obtained. It is found that the third system is the most efficient one and it has the lowest cost. Moreover, the first one has the greatest distilled water with higher temperatures and flow rates.