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Abstract:In this work, the problem of hydrodynamic, heat and mass transfer and stability in a salt gradient solar pond has been numerically studied by means of computational fluid dynamics in transient regime. The body of the simulated pond is an enclosure of height H and length L wherein an artificial salinity gradient is created in order to suppress convective motions induced by solar radiation absorption and to stabilize the solar pond during the period of operation. Here we show the distribution of velocity, temperature and salt concentration fields during energy collection and storage in a solar pond filled with water and constituted by three different salinity zones. The bottom of the pond is blackened and the free-surface is subjected to heat losses by convection, evaporation and radiation while the vertical walls are adiabatic and impermeable. The governing equations of continuity, momentum, thermal energy and mass transfer are discretized by finite-volume method in transient regime. Velocity vector fields show the presence of thin convective cells in the upper convective zone (UCZ) and large convective cells in the lower convective zone (LCZ). This study shows the importance of buoyancy ratio in the decrease of temperature in the UCZ and in the preservation of high temperature in the LCZ. It shows also the importance of the thickness of Non-Convective Zone (NCZ) in the reduction of the upwards heat losses.

Lack of drinking water is a global problem and especially in overdeveloped countries. this is why many research laboratories are focused on solving this problem. one of the simplest, economical, and environmental methods is the use of conventional solar stills. Sand from the city of Illizi in southern Algeria was used in our research to see how it affected solar distillation. So, with a dimension of (0.50 x 0.50 m), two identical solar stills were evaluated, one as a solar still reference (SSR) and the other as a solar still modified (SSM). The SSM contains sand. The findings reveal that there is no discernible difference in performance and that the improvement rate is extremely low, at 0.67 %.

In this paper, the temperature and concentration distributions in an insulated salinity gradient solar pond are studied numerically in transient regime. The dimensionless governing equations are solved by finite-volume method using SIMPLER algorithm with HYBRID scheme. The pond is filled with a mixture of salt and water to form three zones: upper convective zone (UCZ), non-convective zone (NCZ) and lower convective zone (LCZ). The vertical walls and the bottom of the pond are thermally insulated. The bottom of the pond is black painted. The simulation of the insulated salinity gradient solar pond shows the existence of salt diffusion from the bottom to the free surface. This numerical study shows also that the buoyancy ratio increases and decreases the temperature and concentration in the LCZ and in the UCZ, respectively.