Gas transport by thermal transpiration in micro-channels -- A numerical study

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A reliable micro gas pump is an essential element to the development of many micro-systems for chemical gas analyses. At Sandia, the authors are exploring a different pumping mechanism, gas transport by thermal transpiration. Thermal transpiration refers to the rarefied gas dynamics developed in a micro-channel with a longitudinal temperature gradient. To investigate the potential of thermal transpiration for gas pumping in micro-systems, the authors have performed simulations and model analysis to design micro-devices and to assess their design performance before the fabrication process. The effort is to apply ICARUS (a Direct Simulation Monte Carlo code developed at Sandia) to ... continued below

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8 p.

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Wong, C.C.; Hudson, M.L.; Potter, D.L. & Bartel, T.J. August 1, 1998.

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Description

A reliable micro gas pump is an essential element to the development of many micro-systems for chemical gas analyses. At Sandia, the authors are exploring a different pumping mechanism, gas transport by thermal transpiration. Thermal transpiration refers to the rarefied gas dynamics developed in a micro-channel with a longitudinal temperature gradient. To investigate the potential of thermal transpiration for gas pumping in micro-systems, the authors have performed simulations and model analysis to design micro-devices and to assess their design performance before the fabrication process. The effort is to apply ICARUS (a Direct Simulation Monte Carlo code developed at Sandia) to characterize the fluid transport and evaluate the design performance. The design being considered has two plenums at different temperatures (hot and cold) separated by a micro-channel of 0.1 micron wide and 1 micron long. The temperature difference between the two plenums is 30 kelvin. ICARUS results, a quasi-steady analysis, predicts a net flow through the micro-channel with a velocity magnitude of about 0.4 m/s due to temperature gradient at the wall (thermal creep flow) at the early time. Later as the pressure builds up in the hot plenum, flow is reversed. Eventually when the system reaches steady state equilibrium, the net flow becomes zero. The thermal creep effect is compensated by the thermo-molecular pressure effect. This result demonstrates that it is important to include the thermo-molecular pressure effect when designing a pumping mechanism based on thermal transpiration. The DSMC technique can model this complex thermal transpiration problem.

Physical Description

8 p.

Notes

OSTI as DE98006182

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  • 1998 international mechanical engineering congress and exposition, Anaheim, CA (United States), 15-20 Nov 1998

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  • Other: DE98006182
  • Report No.: SAND--98-1897C
  • Report No.: CONF-981107--
  • Grant Number: AC04-94AL85000
  • Office of Scientific & Technical Information Report Number: 674588
  • Archival Resource Key: ark:/67531/metadc707366

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  • August 1, 1998

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  • Sept. 12, 2015, 6:31 a.m.

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  • May 5, 2016, 8:30 p.m.

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Wong, C.C.; Hudson, M.L.; Potter, D.L. & Bartel, T.J. Gas transport by thermal transpiration in micro-channels -- A numerical study, article, August 1, 1998; United States. (digital.library.unt.edu/ark:/67531/metadc707366/: accessed August 23, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.