2
$\begingroup$

Suppose that I have a binary gas mixture at low pressure. Can I calculate the mean free path $\overline{\ell}$ of the gas molecule in a pores of solid material by substituting a molecular weight of a single component by Molecular weight of the binary mixture $M_{m,\rm mix}$ as well as the specific gas constant of this mixture $R_{\rm mix}$, such that I get:

\begin{equation} \overline{\ell} \:=\: \dfrac{3.2\cdot \mu_g}{p}\cdot \left(\dfrac{R_{\rm mix}\cdot T_{\rm abs}}{2\pi\cdot M_{m,\rm mix}}\right)\:\:\:\rm\left[m\right] \end{equation}

I am calculating $\overline{\ell}$ in order to determine the main diffusion mechanism in the pores (Bulk diffusion (Fick), Knudsen or its combination).

Improve this question
$\endgroup$
2
  • $\begingroup$ What is the size of pores ? Is is much greater than the mean free pass in a free gas ? $\endgroup$
    – Poutnik
    Jan 18, 2021 at 14:52
  • $\begingroup$ Mean radius of the pore is $R_p = 8\cdot 10^{-9}\:\left[\rm m\right]$. If used the equation above for the mixture, then the ratio is $\sim 0.725$, which would suggest a combination of Fick' and Knudsen diffusion. However, when I determined a Knudsen number $\rm Kn = \overline{\ell}\big/ d_p$, I obtained $\rm Kn > 10$, which would suggest Knudsen diffusion to be dominant. $\endgroup$
    – Josh E.
    Jan 18, 2021 at 15:13

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.