Permeability and effective thermal conductivity of bisized porous media

Abstract

In the region of minimum porosity of particulate binary mixtures, heat exchange and permeability were found to be higher than the ones obtained with a mono-size packing built with the same small size particles used in the binary packing. This effect was noticed in the range of the particles size ratio 0.1-1.0.The obtained improvement on thermal performance is related to the increase of effective thermal conductivity (ETC) in the binary packing and to the increase in transversal thermal dispersion due to the porosity decrease and tortuosity increase.Permeability can increase by a factor of two, if the size ratio between small and large spheres of a loose packing stays in the range 0.3-0.5.

Starch analysis using hydrodynamic chromatography with a mixed-bed particle column

“…1), approached the experimental values for mono-size glass beads packing and a binary packing formed by a mixture of glass beads with size ratio d = d/D = 0.333/ 1.179 = 0.282 at x D = 0.7 (Dias et al, 2004b;Dias et al, 2007;Mota et al, 2001). This particle size ratio is close to the one used in the experiments below with the binary packing, d = 0.263.…”

“…Obtained result means that for a 200-mm column, which was the one used in this work, the non-isothermal flow occupies only 10% of the total column length. Furthermore (Dias et al, 2007), as is shown in Fig. 3, heat transfer will be improved with a column filled with a binary packing.…”

“…Besides this advantage, in the region of the particle size ratio 0.1 < d < 1.0 and x D $ 0.7 the permeability of the binary bed is maximum (Dias et al, 2007).…”

“…Previous works demonstrated the advantage of a packing formed by a binary mixture of particles of different size at the region of minimum porosity x D $ 0.7 (x D corresponds to the large Dsize particle volume fraction in the mixture) over the mono-size packing (Dias, Fernandes, Mota, Teixeira, & Yelshin, 2007;Dias, Teixeira, Mota, & Yelshin, 2004b;Mota, Teixeira, & Yelshin, 2001). Therefore, the simulation was performed for two cases: (1) a packing formed by mono-size particles of dimension d; and (2) a binary packing obtained from the mixture of large, D, and small, d, size particles at x D = 0.7.…”

The microscopic structure of mono-disperse granular heaps and sediments of particles on inclined surfaces

“…[2][3][4][5] and many references therein. The structural properties of packings are intimately related to certain macroscopic properties of granular matter such as sound propagation, 6 thermal conductivity, 7 permeability, 8 reactivity, 9 tensile strength, 9 dilation 10 and others. Of particular recent interest is the relationship of the microstructure of packings in the jammed state and the process of jamming in granular dynamics, e.g.…”