Knudsen flow

Knudsen flow describes the movement of fluids with a high Knudsen number, that is, where the characteristic length in the flow space is of the same or smaller order of magnitude as the mean free path. It is named after Martin Knudsen

Separation processes

For a gas passing through small holes in a thin wall in the Knudsen-flow regime, the number of molecules that pass through a hole is proportional to the pressure of the gas and inversely proportional to its molecular mass. It is therefore possible to effect a partial separation of a mixture of gases if the components have different molecular masses. The technique is used to separate isotopic mixtures, such as uranium, using gaseous diffusion through porous membranes.[1] It has also been successfully demonstrated for use in hydrogen production, as a technique for separating hydrogen from the gaseous product mixture created when water is heated at high temperatures using solar or other energy sources.[2]

gollark: How many new reasonably-sized ones have moved to/started in California?
gollark: Hmm, Intel has more stuff in the US than I thought, but no manufacturing in California.
gollark: I think it's mostly in... Taiwan? nowadays.
gollark: If it did die, we would probably mostly just lose terrible startups.
gollark: How is this related to Silicon Valley? They make (dubiously useful, a lot of the time) software, not hardware mostly.

See also

References
  1. Villani, S. (1976). Isotope Separation. Hinsdale, Ill.: American Nuclear Society.
  2. Kogan, A. (1998). "Direct solar thermal splitting of water and on-site separation of the products - II. Experimental feasibility study". International Journal of Hydrogen Energy. Great Britain: Elsevier Science Ltd. 23 (2): 89–98. doi:10.1016/S0360-3199(97)00038-4.
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