Experimental testing of a shallow solar pond with continuous heat extraction

The thermal performance of a shallow solar pond (SSP) under the batch and open cycle modes of heat extraction has been investigated experimentally. Experiments have been performed during the summer season of 2001 under different operational conditions for the two modes of heat extraction. The pond performance is investigated in terms of the heat loss coefficients and the rates of energy losses and energy collected. It is found that using an additional glass cover reduces the top U-t and total U-l loss coefficients by 54 and 44%, respectively. The highest value of the rate of energy collected Q(coll.) of 644 W has been achieved when the pond is used with double glass cover and an outer mirror. Further, the tap water is used as a fluid flowing through a heat exchanger (HE), welded to the pond absorber plate, to extract the heat under the open cycle mode. The outlet temperature of the HE's fluid T-fo is found to decrease with the increase of the mass flow rate m(f). The maximum values of T-fo are found to be 55.5, 46.5 and 43.5 degreesC when m(f) equals 0.00054, 0.0030 and 0.00798 kg/s, respectively. Comparisons between the two modes of heat extraction are performed based on the efficiency and the successive operation of the pond. The long-term performance of the pond under the best operational conditions has been investigated by computer simulation for a whole year. It is inferred that the present SSP can be used as a source for the warm water required for domestic applications under climatic conditions similar to Tanta city (latitude 30degrees47'). (C) 2004 Elsevier B.V. All rights reserved.