Binary Diffusion Coefficients for Fluorocarbons in Nitrogen

Published

July 20, 2021

Author(s)

William Sean McGivern, Jeffrey A. Manion

Abstract

Binary gas-phase diffusion coefficients, of interest in physical models of atmospheric and combustion chemistry, have been measured in N2 for the homologous series of refrigerant-related (fluoro)methanes CH4, CH3F, CH2F2, and CHF3. Values have been determined by reverse flow gas chromatography, which has been previously demon- strated to provide accurate results over a wide range of temperatures. Coefficients were measured at temperatures of (27–277)ºC for all species and extending up to 377ºC and 450ºC for CH2F2 and CHF3, respectively, and down to −23ºC for CH4. We also performed measurements for CH4 in air at temperatures of (−27–77) ºC, obtaining values the same as in N2 within 0.3 %, well within our experimental uncertainty. We report the first measurements for CH3F and compare with the limited literature data for the other compounds. Our results agree broadly with earlier measurements in both N2 and air. The greater temperature ranges reported in this work lead to temperature dependences that differ from most previous experiments, although they are consistent with several literature estimates and are similar to temperature expo- nents found for small hydrocarbons in N2. Comparison of the present work with a recent study that found different diffusion coefficients for methane when determined in a typical arrested flow apparatus and a novel "twin tube" method unaffected by sam- ple adsorption shows much better agreement with the the arrested flow results over all common temperatures.

Citation

Journal of Chemical and Engineering Data

Pub Type

Journals

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DOI Link

Keywords

diffusion coefficient, fluorocarbons, refrigerants

Citation

McGivern, W. and Manion, J. (2021), Binary Diffusion Coefficients for Fluorocarbons in Nitrogen, Journal of Chemical and Engineering Data, [online], https://doi.org/10.1021/acs.jced.1c00161 (Accessed November 21, 2024)