This study investigates the thermal performance of the Lower Convective Zone (LCZ) in a Salt-Gradient Solar Pond (SGSP) using numerical simulations. The model is developed from an experimental prototype reported in the literature, with a computational domain of 20 m × 20 m × 1.5 m. A heat exchanger tube of 0.10 m diameter is placed inside the LCZ to absorb the stored heat. The inlet mass flow rate is set to 0.078 kg/s, and the boundary conditions are based on climatic data from August 2016, where the ambient temperature was 29.5°C and the solar radiation was 792 W/m². The model is validated against experimental results, showing an average deviation of 4% in outlet fluid temperature. The effect of varying mass flow rates from 0.039 kg/s to 0.312 kg/s on heat transfer is evaluated. To enhance thermal extraction, four heat exchanger geometries are tested: standard straight tube, inverted-U tube, zigzag coil with three bends, and zigzag coil with four bends. Results indicate that higher mass flow rates reduce LCZ temperature, while modified geometries significantly improve thermal performance. The zigzag coil with four bends achieves the highest outlet temperature of 75.55°C, compared to 51.38°C for the standard configuration, confirming the advantage of spiral geometry in maximizing heat extraction.
Elakrout et al. (Sun,) studied this question.