Thermal conductivity of air in the range 312 to 373 K and 0.1 to 24 MPa |
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Authors: | A C Scott A I Johns J T R Watson A A Clifford |
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Affiliation: | (1) National Engineering Laboratory, East Kilbride, G75 0QU Glasgow, UK;(2) Department of Physical Chemistry, The University, LS2 9JT Leeds, UK |
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Abstract: | We have used the transient hot-wire technique to make absolute measurements of the thermal conductivity of dry, CO2-free air in the temperature range from 312 to 373 K and at pressures of up to 24 MPa. The precision of the data is typically ±0.1%, and the overall absolute uncertainty is thought to be less than 0.5%. The data may be expressed, within their uncertainty, by polynomials of second degree in the density. The values at zero-density agree with other reported data to within their combined uncertainties. The excess thermal conductivity as a function of density is found to be independent of the temperature in the experimental range. The excess values at the higher densities are lower than those reported in earlier work.Nomenclature
Thermal conductivity, mW · m–1 · K–1
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Density, kg · m–3
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C
p
Specific heat capacity at constant pressure, J · kg–1 · K–1
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T
Absolute temperature, K
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q
Heat input per unit wire length, W · m–1
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t
Time, s
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K(= / C
p)
Thermal diffusivity, m2 · s–1
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a
Wire radius, m
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Euler's constant (=0.5772 )
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p
c
Critical pressure, MPa
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T
c
Critical temperature, K
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c
Critical density, kg · m–3
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R
Gas constant (=8.314 J · mol–1 · K–1)
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V
c
Critical volume, m3 · mol–1
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Z
c(=p
c
V
c/RT
c)
Critical compressibility factor |
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Keywords: | Air hot-wire technique thermal conductivity transient technique |
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