Effect of pore size distribution and air flux on mass transport in direct contact membrane distillation

Characterization and evaluation of carbon nanotube Bucky-Paper membranes for direct contact membrane distillation

“…The dominating regime is indicated by the Knüdsen number (K n ), defined as the ratio of the mean free path (λ) to the pore diameter (d) [14][15][16]. The mean free path is defined as:…”

“…For Knüdsen numbers, K n > 1, the molecule -pore wall collisions dominate leading to Knüdsen type flow: For isoporous membranes with circular pores the permeance is given by [7][8][9][10][11][12][13][14][15][16][17]:…”

“…The total resistivity of the system is then equal to the sum of both Knüdsen and Molecular resistivity. This was modelled as resistances in series in previous studies [15], leading to the following equation for permeance: …”

“…The images were analysed using the software, ISIS and the edge-pores were not taken in consideration for the calculations. The minimum, mean and maximum average pore size distributions were calculated using Feret's approach [13][14][15][16][17][18][19][20]. In this method, 3 diameters are calculated for each pore, corresponding namely to the minimum, the mean and the maximum pore size, which gives information on pore shape distribution.…”

“…This could lead to an increased number of molecular-wall collisions and hence a more tortuous path for water vapour through the BP membrane reducing permeability. A tortuosity factor of 2 was assumed for both membranes in the theoretical calculations [15].…”