solar pond; convective stability; thermal storage; large-area solar collector
The local stability criteria of solar salt ponds with general gradients are investigated. Stability formulations based on ‘normal mode analysis,’ as well as the ‘Green function technique’ are considered. Calculations corresponding to a model solar pond (S0 = 50 kg/m3, S1 = 100 kg/m3, T0 = 20°C, T1 = 95°C) often observed to be unstable in practice are carried out for constant, linear, and nonlinear gradients. It is shown that the approximation of the full Green function by the retarded Green function may lead to considerable error in stability analysis.