Thermal behavior of a large salinity-gradient solar pond in the city of Mashhad



By applying a model of finite differences, the thermal behavior of a large solar pond in the city of Mashhad in the north east of Iran, is studied in this paper. The 32-year data of sunny hours to day-length ratio are used for the estimation of global radiation. The temperature data of a similar duration are used for evaluating the ambient temperature. The effects of the variation of different zone thicknesses on pond performance are studied. It is observed that the upper convective zone thickness should be as thin as possible, the non-convective zone might be from 1 to 2 m and the lower convective zone thickness may be designed based on the application needs. A thicker non convective zone provides more insulation against heat losses, and a thicker lower convective zone supplies a higher storage capacity, though with a lower operating temperature.
The heat may be extracted from the pond by either a constant or a variable loading pattern. The appropriate loading pattern can be selected based on the needs and operational temperature. The LCZ temperature of the pond, under several heat extraction patterns, is also presented for practical applications.