Mathematical modeling of salt gradient solar pond

Mathematical Modeling of Salt Gradient Solar Pond SUMMARY Keywords : Salt gradient solar pond, mathematical model, analytical and numerical solutions. Storage is one of the most critical problems of almost all solar energy applications due to its intermittent nature. Low storage devices usually amount to a considerable fraction of the total cost of the solar energy transduction systems into some usable form of energy. A realistic solution to the storage problem for low temperature applications is provided by solar ponds. Solar ponds both collect and provide storage of solar radiation in the form of heat In a solar pond, no distinction exists between the collecting and storage devices. The same bulk of water serves both purposes simultaneously. Among the solar pond type, salt gradient solar pond is the most studied and most common type. In an actual salt gradient solar pond, there are three distinct layers; upper convective zone (UCZ), non-convective zone (NCZ) and lower convective zone (LCZ). The UCZ is the topmost layer of solar pond. It is relatively thin, uniform and consists almost wholly of fresh water. The NCZ is just below the UCZ and has a step salinity gradient which suppresses the existing convective motions inn the LCZ. Thus solar ponds bom collect and provide storage of solar radiation in the form of heat The LCZ acts as a seasonal solar storage and it has high uniform salt concentration. In order to understand how a pond works, mathematical modeling is required. In this study, salt gradient solar pond was constructed for making of an experimental study at the Istanbul Technical University in 1994 and a one-dimensional transient mathematical model for predicting the thermal performance of the pond developed and presented. In the model, the solar pond structure explained as well as heat and mass transfer phenomena. The mathematical model based on one-dimensional unsteady state heat conduction model with an internal heat generation, energy and mass balance equations for the UCZ, NCZ and LCZ, all of which are forming the solar pond, are written in terms of differential equations. These equations are solved analytically and numerically. The temperature profiles of the model pond were obtained for the same dates as the experimental study. The results obtained from that solutions are compared with the experimental results which were performed in that sote? pond before-hand. The comparison of the experimental and theoretical temperature profiles shows that they are qualitatively in good agreement The concentration profile of the model paid was obtained after the one week from the filling up time of the pond and it is quantitatively and qualitatively in good agreement in according to physics of solar pond concentration gradient. According to obtained results from this study, it is concluded that if the solar pond is constructed in actual and right situation, the solar pond can be an alternative and economic energy storage device in applications.