Physics & Astronomy ETDs

Publication Date



The diffusion equation for salt gradient solar ponds has been modified to include the Soret effect (a thermal cross-effect due to the temperature gradient). The contribution of the Soret effect to the diffusion flux of salt is shown to be on the order of 4% in the winter and 28% in the summer for the UNM NaCl solar pond. The traditional stability criterion for solar ponds remains practically unchanged by the Soret effect. However, the contribution of non-constant properties (diffusion coefficient, thermal diffusivity and viscosity)--which have been neglected so far--seems to be significant. Saturated solar ponds are described by a system of differential equations which include the Soret effect, the formation and redissolving of crystals. The analytical solutions of this system are given for the steady-state and constant properties. A laboratory experiment using KNO3 confirms the existence of a stable saturated gradient. Temperatures of up to 90° C and temperature gradients of up to 2°C/cm were used in the experiment without any sign of convective layers. A saturated gradient at steady state includes a super saturated region close to the surface which results in the fallout of crystals in that region. The diffusion flux of salt is thus balanced by a flux of crystals downwards and the net flux of salt is zero in a steady state.

Degree Name


Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

Howard Carnes Bryant

Second Committee Member

Derek B. Swinson

Third Committee Member

Seymour Samuel Alpert

Project Sponsors

The Department of Energy Grant No. EG-77-S-04-3977



Document Type