Computational studies on a solar pond

Abstract

Salt gradient solar pond is an environmentally friendly and sustainable method or rather a system to store solar energy in the form of heat energy. The solar pond is able to achieve this by utilising salt concentration gradient which prevents mixing of temperatures when a water body is heated due to solar radiation. As solar radiation falls on a water body it is absorbed in the layers of water, however the difference in temperature from the upper and the lower layer is nullified as the temperatures in the various layers intermix, and the temperature difference is lost. A Salt gradient solar pond has three zones: the Upper Convective Zone, with uniform temperature and concentration and is generally formed from fresh water or locally available water; below the Upper Convective Zone is the Non Convective Zone , which occupies almost half the depth of the pool, this zone has a salinity concentration gradient and subsequently a temperature gradient; the bottom Zone is termed as the Lower Convective Zone , which has the highest concentration and temperature and it serves as the main heat collection and thermal storage-medium. The inner workings of a solar pond is governed by equations of Temperature, Species and Momentum Transport. In this work a solver has been developed using OpenFOAM, for solving the governing equations of Temperature, Species and Momentum transport which dictate the behaviour of a Salt gradient solar pond .A thin square model of the Salt gradient solar pond has been made. The three zones of Lower Convective Zone, Non Convective Zone and Upper Convective Zone have been provided the height of 0.4m, 0.5m and 0.1m respectively. The solver is then executed for the model pond with three varying values of incident radiation 250W/m2, 500W/m2 and 1000W/m2, varying values of Salt concentration in the Lower Convective Zone, and different boundary conditions for concentration at the bottom boundary of the Pond. It has further been tested against experimental data on Solar Ponds from published literature for validation.