Modeling of Thermal Transpiration Flows for Knudsen Compressor Optimization

Abstract

Rarefied gas flows through two-dimensional finite length capillaries are studied numerically with the goal of performance optimization of a nanomembrane-based Knudsen compressor. Both density and temperature gradient driven flows are considered in a wide range of Knudsen numbers from 0.05 to 75. The length-to-height ratios from 5 to 30 were examined. Three different wall temperature distributions were considered, namely, linear, step-wise, and a non-monotonic profile typical for a radiantly heated Knudsen compressor membrane. The direct simulation Monte Carlo method was used for shorter channels, and a discrete ordinate method for the solution of the BGK model equation is utilized for a long channel. The mechanism for the Knudsen minimum in flow conductance is quantitatively explained, the short channel end effects are characterized, and the sensitivity of the mass flow rate to a non-monotonic temperature distribution is shown.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2005
Accession Number
ADA433782

Entities

People

  • A. A. Alexeenko
  • Andrew D. Ketsdever
  • E. P. Muntz
  • S. F. Gimelshein

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Air Force Research Laboratories
  • Compressors
  • Equations
  • Flow Rate
  • Gas Flow
  • Gases
  • Knudsen Number
  • Mass
  • Mass Flow
  • Mean Free Path
  • Membranes
  • Microvessels
  • Monte Carlo Method
  • Pressure Distribution
  • Rarefied Gases
  • Temperature Gradients
  • Two Dimensional

Fields of Study

  • Physics

Readers

  • Computational Fluid Dynamics (CFD)
  • Plasma Physics.