Role of the Knudsen layer in determining surface reaction rates based on sticking coefficients

Peng Zhang, Chung K. Law

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Recent studies on catalytic micro-combustors and LPCVD (Low-pressure Chemical Vapor Deposition) have shown the necessity to include effects of the Knudsen layer on surface reactions. In the present work, a weakly rarefied flow of a binary gas mixture with surface reactions was analyzed by using Hamel's model of the Boltzmann equation and Nocilla's model of molecule-wall interaction. Particular interest was placed on the interaction between the Knudsen layer and surface reactions. The theoretical results show that the Knudsen layer modifies the incident flux of the molecules striking the surface and consequently the surface reaction rate, while the surface reactions in turn modify the flow structure in the Knudsen layer through the non-zero net flux at the surface. A general rate expression for a one-step surface reaction based on the sticking coefficient was obtained and can be readily extended to more complex surface reaction mechanisms. The assumptions underlying the widely-used Motz-Wise correction formula for surface reaction rate are discussed.

Original languageEnglish (US)
Title of host publicationFall Technical Meeting of the Eastern States Section of the Combustion Institute 2007 "Chemical and Physical Processes in Combustion"
PublisherCombustion Institute
Pages628-631
Number of pages4
ISBN (Electronic)9781604239454
StatePublished - Jan 1 2007
EventFall Technical Meeting of the Eastern States Section of the Combustion Institute 2007: Chemical and Physical Processes in Combustion - Charlottesville, United States
Duration: Oct 21 2007Oct 24 2007

Publication series

NameFall Technical Meeting of the Eastern States Section of the Combustion Institute 2007 "Chemical and Physical Processes in Combustion"

Other

OtherFall Technical Meeting of the Eastern States Section of the Combustion Institute 2007: Chemical and Physical Processes in Combustion
CountryUnited States
CityCharlottesville
Period10/21/0710/24/07

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

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  • Cite this

    Zhang, P., & Law, C. K. (2007). Role of the Knudsen layer in determining surface reaction rates based on sticking coefficients. In Fall Technical Meeting of the Eastern States Section of the Combustion Institute 2007 "Chemical and Physical Processes in Combustion" (pp. 628-631). (Fall Technical Meeting of the Eastern States Section of the Combustion Institute 2007 "Chemical and Physical Processes in Combustion"). Combustion Institute.