Application of porous layer in enhancing stability of salt-gradient solar pond

The salt gradient solar pond (SGSP) can capture and store a large amount of solar energy for a long time, making it an efficient and economical solar energy facility. The long-term operational stability of SGSP can be damaged by interface erosion, which is caused by thermosolutal convection. Attaching porous layers is a promising approach to slow down interface erosion. In this study, we simulated the unsteady thermosolutal convection in SGSP with Lattice Boltzmann methods (LBM). The effects of a porous layer on salinity gradient stability are analyzed with boundary equilibrium and marginal criterion. The simulation results show that the SGSP becomes thermally unstable when the interface erosion begins. By attaching a porous layer to the bottom surface, the convective flow is weakened and the instability in SGSP is reduced. The stability analysis shows that the thermally unstable state in SGSP transits into a theoretically stable state by attaching a porous layer. As the stable state is prolonged, the fluid temperature in the storage layer increases. We also find that reducing the permeability of the porous layer or increasing the layer thickness prolongs the stable state. This study helps to improve future SGSP design and promote its engineering application.