Solar Water Desalination 2-D (Species Transport) , ANSYS Fluent CFD Simulation Training

The present study investigates the performance of a solar-still thermal desalination unit by ANSYS Fluent software. The current model consists of a small chamber with a sloping glass surface at the top. The resulting vapor impacts the cold glass surface and undergoes a distillation process. Pure water from hot vapor distillation moves down the slope of the glass plate and discharges as pure water.

One of the thermal methods of water desalination is using solar desalination units. In solar water desalination, solar energy is used as a heat source and causes the evaporation process. In the functional mechanism of this type of desalination, surface evaporation occurs by solar energy. The produced vapor collides with the cold surface of the glass and converts to pure water after distillation.

Desalination Methodology

The solar heat passes through the glass to the water's surface in the enclosure and causes surface evaporation (applying a UDF for surface evaporation).

The Species Transport method is used. This method does not simulate saline water flow in the device. Unlike multiphase simulations with much heavier computations, this method assumes that there is a mixture of air and vapor inside the chamber interior.

The simulation focuses solely on the amount of vapor produced in the system. The present study aims to investigate the amount of vapor produced on the water surface and the cold surface of the sloping plate.

Also, the solver is Steady-State. The present 2-D model was designed by Design Modeler software. The geometry consists of a sloping glass surface at the top and a horizontal water plate at the bottom. A Structured mesh was performed using ANSYS Meshing software. The element number is 16,000.

Desalination Conclusion

This method assumes a mixture of air and vapor inside the chamber interior and does not simulate distilled water flow.

In fact, at the beginning of the simulation, the space inside the chamber is filled with air only; the bottom plane of the chamber is considered the surface of the water, and since the water evaporates on the surface, it is assumed that the surface consists of vapor.

It is also assumed that the sloping plate where the steam collides is composed only of vapor. So water and air mass fraction contours completely show the evaporation in the device.