A Experimental Study of a Potassium Nitrate Salt - Solar Pond.

The collection and storage of solar energy in a body of water is possible by preventing convection with a stabilizing salinity gradient. An outdoor salt gradient solar pond using KNO(,3) was designed, constructed, and studied at the University of New Mexico. This experimental pond was formed using a steel cylindrical shell eight feet in diameter and 13 feet long embedded in the earth with its axis of symmetry vertical. The interior of the shell was sprayed with a one foot layer of polyurethane foam (R50) on the walls and bottom. The lower six feet of the cavity was filled with dry sand. The active KNO(,3) solution occupied the upper 6 feet of the cavity, contained by a butyl rubber liner. A salt gradient was established in the fall of 1981 and the behavior of the pond was monitored for a period of nine months. The lower storage layer of this pond reached a high temperature of 82(DEGREES)C in late July 1982. There is a possibility to increase the temperature of the potassium nitrate solution over 100(DEGREES)C and to increase the concentration of the solution up to 77%. Apart from economic considerations, which were not included in this study, this prototype pond suggests that KNO(,3) ponds show considerable promise for the collection and storage of solar energy. The application of KNO(,3) solar pond for the supply of the industrial process heat may be economically and technically feasible. The solar pond which may have some potential, used a system for solar collection and seasonal storage, needs more research before prototypes are constructed.