An experimental study on natural convection from vertical surfaces embedded in porous media

Mass-transfer Coefficients for natural convection from vertical surfaces embedded in saturated porous media have been experimentally obtained by utilizing a limiting diffusion current technique based on cathodic reduction of cupric ions in anacidic solution. The data correspond to a high Rayleigh number and exhibit non-Darcian effects. Final results, when compared with available mathematical models, revealed that a model based on Brinkman, extended Darcy's flow model with a corrected constant predicted mass-transfer coefficients closely. For the spherical packing materials the data fit well in, Sh(L)/(*) = 3.32(Ra(L)/(*)/Da(L)^0.26, where Ra(L)/(*) and Da(L) are a modified Rayleigh number and Darcy's number, respectively.