Modeling of the Surface Convective Layer of Salt-Gradient Solar Ponds

Abstract

A one-dimensional numerical model is developed to predict the diurnal variations of vertical temperature and concentration profiles in salt-gradient solar ponds. The model employs augmented thermal and mass diffusivities due to turbulent wind mixing and double-diffusive convection. Numerical results indicate that the thickness of the surface convective layer increases with wind speed (or the wavelength of the surface wave). Double-diffusive convection is, in the absence of wind, capable of sustaining a mixed layer at the surface when strong cooling occurs over the pond. In field ponds, the surface convective layer is probably maintained as a result of the combined action of wind-generated turbulent mixing and double-diffusive convection.

Transient performance of a two-dimensional salt gradient solar pond—A numerical study

“…However, the majority used a one-dimensional model to simulate and analyse the performance of solar ponds (Nielson, 1979;Wang and Akbarzadeh, 1983;Weinberger, 1964;Tabor, 1981; Panahi et a1 1983; Winsberg, 1981;Hull, 1980;Rubin et al, 1984;Kooi, 1979;Joshi and Kishore, 1985;Jayadev and Henderson, 1984;Meyer, 1983;Cha and Schertz, 1982;Hassab et al, 1987;Kamal, 1986;Newell, 1980;Atkinson and Harleman, 1933). The one-dimensional model, which assumes small convective motions and very slow salt diffusion reflects almost a closer image to the real case.…”

Heat extraction from the ANL research salt gradient solar pond

“…For this case, it was found that an inside tube diameter of .00804 m, or 8.04 mm, gave Rai a value of 4.18x10 12 . Therefore, if the heat exchange tubes had an inside diameter of 8.04 mm or less, natural convection through the tubes would be completely suppressed.…”

“…Currently, no complete understanding of the dynamical behavior of this zone is available. A onedimensional model of this zone was developed [12] using models that had previously been used in oceanography and limnology.…”

“…The program calculated successive values of Rak and if the current value of Rak was less than 4.18x10 1 2 , the quantity 2.000(1.0 -Rak/4.18x10 12 ) was added to the current value of the Nusselt number, and the next value of Rak was calculated.…”

Salt-gradient solar ponds: summary of US Department of Energy sponsored research

“…The use of direct contact heat exchangers might substantially reduce this cost. SERI has made an intensive investigation of this substitutioT he possibility of using a direct-contact preheater/evaporator was investigated (References 3-16 and [3][4][5][6][7][8][9][10][11]. A problem usually encountered with direct-contact heat exchangers is loss of working fluid through absorption by the heat transfer fluid.…”