Heat transfer in a molten salt filled enclosure absorbing concentrated solar radiation

Numerical results presented in terms of isotherms and streamlines show a nonlinear temperature profile consisting of distinct layers where thermocapilarity and buoyancy effects are evident. Fluid flow development in the lower layer is found to vary significantly with time and exhibits an initial stage, transitional stage and quasi-steady stages. The magnitude of the natural convection and the duration of each stage is found to decrease as the aspect ratio increases from 0.5 to 2. Calculation of the average heat transfer reveals that the Nusselt Rayleigh number relationship is not uniformly linear and the average heat transfer over the lower boundary surface increased with increasing Ra.