Diffusion through a stagnant film

Input(s)

$\boldsymbol{D}_{\boldsymbol{A} \boldsymbol{B}}$: Diffusivity $\left(\mathrm{cm}^{2} / \mathrm{s}\right)$

$z_{1}$: Initial Position (ft)

$z_{2}$: Output Position (ft)

$\boldsymbol{x}_{\boldsymbol{A} 1}$: Mole Fraction of A1 $(\mathrm{g} / \mathrm{ft})$

$\boldsymbol{x}_{\boldsymbol{A} 2}$: Mole Fraction of A2 $(\mathrm{g} / \mathrm{ft})$

$x_{b}$: Mole Fraction of B in the Logarithmic Mean of Thermal Concentrations (mol/ft $\mathrm{t}^{3}$ )

c: Total Molar Concentration $\left(\mathrm{mol} / \mathrm{ft}^{3}\right)$

Output(s)

$\mathrm{N}$: Combined Molar Flux $\left(\mathrm{mol} / \mathrm{ft}^{2} \mathrm{~s}\right)$

Formula(s)

$$ \mathrm{N}=\frac{\mathrm{c} * \mathrm{D}_{\mathrm{AB}} *\left(\mathrm{x}_{\mathrm{A} 1}-\mathrm{x}_{\mathrm{A} 2}\right)}{\left(\mathrm{z}_{2}-\mathrm{z}_{1}\right) *\left(\mathrm{x}_{\mathrm{b}}\right)} $$

Reference(s)

Bird, R.B., Stewart, W.E. and Lightfoot, E.N. (2002). Transport Phenomena (Second Ed.). John Wiley \& Sons, Chapter: 18, Page: 548 .