English abstract
Salt gradient solar ponds are large area, low cost devices for the collection and storage of solar energy. The stored energy can be used for power production, cooling, heating applications and thermal desalination. Solar ponds may be constructed with sloped walls to minimize the ground heat loss and eliminate shadows, which are usually encountered when vertical walls are used. The slopping walls absorb heat that leads to the generation of convective cells that affect the stability of the gradient zone.
A numerical model was developed and an investigation was conducted to study the effect of tilting angle of the wall, the salt concentration and the heat flux on the onset of generated convective cells, using PHOENICS CFD package. The predicted results gave a better insight into the convective layers characteristics. The numerical model developed in this project can be used to help solar ponds practitioners with the design and operations of solar ponds.
The predicted results demonstrated that the numerical model was able to capture all features of the convective cells in solar ponds. The achieved result indicated significant effect of inclination of the sloped wall, salt concentration and heat flux on the stability of solar pond. The activity of the convective layers increases with the decrease in the angle of the wall. As salt concentration is increased, the pond becomes more stable because the concentration is related to the density. The activity of the motion of the convective cells in the fluid increases if the heat flux is increased. The general predicted trends agree very well with experimental and theoretical trends. Moreover, the values of the predicted distance of front of the convective layers agree well with the experimental results for different tilt angles.
