Relative study of steel solar pond with sodium chloride and pebbles

The salt-gradient solar pond is the pre-eminent solar desalination process for storing thermal energy. Due to the high concentration of salt content present in the lower convective zone heat will be stored for a longer period and will supply thermal energy at whatever time is required to have a temperature varying from 50 °C to 90 °C. This paper proposes an experimental and theoretical analysis of the convective type solar pond with trapezoid cross sections with the surface area of 1.7 m2 and depth of 0.5 m made-up of 2 mm thickness mild steel sheet-metal lined by 20 mm and 2 mm thickness of thermo styrene, high density polyethylene sheet. The salinity-gradient is having three zones and these zones are separated due to salt concentration, each zone is having a varying thickness of 1.5 m (upper zone), 2 m (middle zone) and 1 m (lower zone). K-type thermocouple and solar power meter is used to measure the variation of temperature and solar radiation of the pond, thermocouples were space equally of 5 cm at six intervals and the readings were taken for eight hours per day and it is recorded during the months of December and January for further analysis. Experiments are conducted to find efficiency with NaCl and Pebbles. The experimental result reveals that efficiency is higher in NaCl (7%) compared with Pebbles (4%).