Natural Convection Mass Transfer at Salt-Brine Interfaces

Experimental measurements of the rate of dissolution (mass transfer) at salt-brine interfaces have been made for variation of brine concentration from fresh water to near saturated brine, and variation of surface orientation from horizontal (facing downward) through the vertical to “near” horizontal (facing upward). Salt samples used were cut from an underground mine and the dissolution results are for “rough” surfaces—that is, after the surface has developed. Samples of approximately 1 m long were used, and the results obtained and presented are for turbulent flow. The correlated results are presented in the form of a coefficient C_T as a function of θ (angle from vertical) where C_T(θ) = Sh/(GrSc)^1/3. The coefficient is found to be a very strong function of angle, being larger for the unstable orientations and smaller for the stable orientations than for the vertical. The data are compared to other turbulent natural convection mass and heat transfer data for vertical and inclined surfaces, and are found to exhibit considerably greater convection transport coefficients than for smooth surfaces.