Membrane tortuosity

Tortuosity is a long-range property of a porous medium, which qualitatively describes the average pore conductivity of the solid. It is usual to define x by electrical conductivity measurements. With knowledge of the specific resistance of the electrolyte and from a measurement of the sample membrane resistance, thickness, area, and porosity, the membrane tortuosity can be calculated from eq 3. 

The membrane tortuosity (r) reflects the length of the average pore compared to the membrane thickness. Simple cylindrical pores at right angles to the membrane surface have a tortuosity of one, that is, the average length of the pore is the... 

T denotes membrane tortuosity (dimensionless) e denotes membrane porosity (dimensionless)... 

Dab = molecular diffusion coefficient in the gas filling the pores eM = membrane porosity tm = membrane tortuosity 8 = membrane thickness... 

For the membrane and solvent here, is the membrane thickness (30 pm), x is the tortuosity (3 value obtained from Celgard GmbH), and is the diffusion coefficient of the solute complex in membrane. The membrane tortuosity was also determined by the Wakao-Smith relation, expressed as the inverse of the membrane porosity, which almost matches the value suggested by Celgard GmbH [92]. 

Teramoto et al. (1996) compared the predictions obtained using both methods with experimental data and found that their approach gave the most accurate results. The Guha model tended to over-estimate the CO2 flux and it was cited that the reasons for this were the omission of the second reaction step and the manner in which the authors treated the membrane tortuosity, x. Multiplying the membrane thickness by some function of x, results in an effective diffusion path along which the concentration... 

Where J = flux in mass/unit area/unit time D = diffusion coefficient Ac = concentration decrement across the membrane e = membrane porosity T = membrane tortuosity il = membrane thickness... 

Here, the diffusion length in the z-direction is r Sm, where Sm is the membrane thickness and is the membrane tortuosity. At steady state, Niz in expression (3.4.89b) is constant, and... 

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