Theoretical gas phase mass transfer coefficients for endogenous gases in the lungs

Peter Condorelli, Steven George

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Gas phase mass transfer coefficients for nitric oxide (NO), ethanol (EtOH), and water vapor (H2O) were determined for typical conducting airway geometry and tracheal flows (5 × 10-5 and 5 × 10-4 m3 s-1), by solving the steady-state two-dimensional diffusion equation. A constant absolute production rate with first order consumption reactions in pulmonary tissue was assumed for NO. For EtOH and H2O, constant concentrations were assumed in the blood and tissue, respectively. Results, expressed in terms of the average Sherwood number (Sh), were correlated with the Peclet (Per) number, and the length-to-diameter (L/D) ratio for each airway branch in terms of a lumped variable, Per(L/D)n. (Sh) increases as the solubility of the gas in tissue and blood increases. In addition, Sh passes through a minimum value at Per(D/L)n equal to approximately one when axial convection and diffusion have equal but opposite magnitudes. We conclude that Sh is not a monotonic function of Per(L/D)n within the entire airway tree and that it depends on the physical properties of the gas in the tissue. This conclusion contrasts with previous experimental and theoretical correlations.

Original languageEnglish (US)
Pages (from-to)326-339
Number of pages14
JournalAnnals of Biomedical Engineering
Volume27
Issue number3
DOIs
StatePublished - Jan 1 1999

Keywords

  • Airways
  • Bifurcation
  • Diffusion
  • Pulmonary
  • Sherwood number
  • Tubes

ASJC Scopus subject areas

  • Biomedical Engineering

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