Molecular Flow

  • Octave Levenspiel
Part of the The Plenum Chemical Engineering Series book series (PCES)

Abstract

The mean free path (mfp) of molecules increases when the gas pressure is reduced, and at low enough pressure the (mfp) is so large that the molecules begin to bounce from wall to wall of the flow channel rather than collide with each other. When this happens the character of the flow changes. Thus, different flow regimes are encountered depending on the value of the ratio
$$\textup{Kn}=\frac{(mfp)}{d}=\frac{\textup{mean\;free\;path\;of\;molecules}}{\textup{diameter\;of\;flow\;channel}}$$
where Kn is called the Knudsen number.

Keywords

Laminar Flow Flow Regime Leak Rate Vacuum Pump Vacuum System 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References and Further Readings

  1. A. S. D. Barrett, and B. D. Power, in Chemical Engineering Practice (H. W. Cremer and T. Davies, eds.), Vol. 5, Academic Press, New York (1958).Google Scholar
  2. S. Dushman, Scientific Foundation of Vacuum Technique, Wiley, New York (1949). Complete and comprehensive.Google Scholar
  3. M. Knudsen, Ann. Phys. 28, 75, 999 (1909). These papers laid the foundations and developed the basics of the whole field.CrossRefGoogle Scholar
  4. R. Loevinger, in Vacuum Equipment and Technique, (A. Guthrie and R. K. Wakerling, eds.), Chapter 1, McGraw-Hill, New York (1949). A nice, simple treatment of pumping systems.Google Scholar

Copyright information

© Springer Science+Business Media New York 1998

Authors and Affiliations

  • Octave Levenspiel
    • 1
  1. 1.Oregon State UniversityCorvallisUSA

Personalised recommendations