Special Issue Article
Thermal Performance Study on Parametric Variation of Storage Volume of Water Loaded in a Small and a Domestic Size Experimental Shallow Solar Ponds (SSP)
The thermal performance of a small size and a domestic size Shallow Solar Pond (SSP) have been investigated by varying the volume of water stored in the SSPs and their performance are compared. The thermal performance curve for SSPs has been obtained and from the curve the heat loss coefficient of the SSPs has been experimentally determined. A small size shallow solar pond have been fabricated using a ceramic sink of size 0.47m x 0.30m x 0.13m and was properly insulated along the inside bottom and side walls with black Polyurethane foam (PUF) in sheet form of thickness 12mm. A Low Density Polyethylene (LDPE) black sheet liner of 200 micrometer thickness has been laid all along the bed side and inner peripheral sides for better solar energy capture. Once the study volume of water is loaded in the SSP, a clear transparent PVC sheet of 150 micrometer thickness was laid over the top surface of water and used as evaporation suppressing membrane. A single transparent glass cover of 5mm thickness was fixed for air leak proof on top of SSP inorder to reduce the convective heat losses due to wind effect. Copper - constantan thermocouples have been used in different numbers to measure the temperature at different locations of the SSP system. Small size SSP was made for a maximum storage volume of 10 liters and the study was conducted initially loaded with 2 liters of water and further studies were made for the increased storage volumes of water in steps of 2 liters upto 10 liters. It is inferred from the obtained results that the temperature attained by the small size SSP was found to have maximum at 81.50C, 74.20C, 710C, 66.50C, 700C for the storage volumes of 2, 4, 6, 8, 10 liters respectively. The mean instantaneous heat collection efficiency was estimated as 37.2% and the estimated mean heat loss coefficient was 4.23 W/m2 0C. The mean τα product of the system is estimated as 0.48. A domestic size shallow solar pond has been fabricated inorder to hold larger volume of water, using a metal tray made of GI sheet of size 1.02m x 0.68m x 0.10m and was tested for its performance for the increased storage volumes from 15 liters to 50 liters in steps of 5 liters a day. The domestic size SSP has attained maximum temperatures of 870C, 83.30C, 88.30C, 86.30C, 75.40C, 700C, 620C, 75.50C, when the domestic SSP loaded with the storage volumes of 15, 20, 25, 30, 35, 40, 45, 50 liters respectively. The mean instantaneous heat collection efficiency was estimated as 51.5% and the estimated mean heat loss coefficient was 3.84 W/m2 0C. The mean τα product of the system is estimated as 0.68. The maximum temperature of the SSP water was found to be decreasing with the increase in the storage volume of water. The shallow solar pond of the type discussed here could be utilized as a source of hot water which could be suitably used for the domestic and industrial heat applications process. A large size shallow solar pond of similar type could provide necessary hot water for the generation of even electrical power when properly designed and coupled through an ORC engine.