Reference Correlations of the Thermal Conductivity of Cyclopentane,iso-Pentane, andn-Pentane

Abstract

New, wide-range reference equations for the thermal conductivity of cyclopentane, iso-pentane, and n-pentane are presented. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. In the case of the dilute-gas thermal conductivity, a theoretically based correlation was adopted in order to extend the temperature range of the experimental data. In the critical region, the enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter, estimated by a predictive scheme. The thermal-conductivity equations behave in a physically reasonable manner over a wide range of conditions that correspond to the range of validity of the most accurate equations of state for each fluid. The estimated uncertainties of the correlations are dependent on the availability of accurate experimental data for validation, and are different for each fluid, varying from 1% (at the 95% confidence level) for the liquid phase of iso-pentane over the temperature range 307 K < T < 355 K at pressures up to 400 MPa (where high-accuracy data are available) to a more typical 4% for the liquid phase of cyclopentane over the temperature range 218 K < T < 240 K at pressures to 250 MPa. Estimated uncertainties in the gas phase are typically on the order of 3%-5%. For all three fluids, uncertainties in the critical region are much larger, since the thermal conductivity approaches infinity at the critical point and is very sensitive to small changes in density.

Models for viscosity, thermal conductivity, and surface tension of selected pure fluids as implemented in REFPROP v10.0

“…There is considerable scatter among the liquid data sets, and we estimate the uncertainty for the liquid phase is 5 % for pressures up to 100 MPa. We do not cover the thermal conductivity or surface tension here as there are existing correlations for these properties for n-pentane in literature publications (Mulero, Cachadiña, & Parra, 2012; Perkins, 2015). ______________________________________________________________________________________________________ …”

“…For the liquid phase we estimate the uncertainty is 10 % along saturation at temperatures above 120 K. At lower temperatures and at higher pressures, the uncertainty is larger. We do not cover the thermal conductivity or surface tension here as there are existing correlations for these properties for isopentane in the literature (Mulero et al, 2012;Vassiliou et al, 2015). ______________________________________________________________________________________________________ …”

“…The estimated uncertainty in the gas phase is 3 %, and in the liquid at temperatures above 223 K and pressures up to 400 MPa is 2 %. Thermal conductivity (Vassiliou et al, 2015) and surface tension (Mulero & Cachadiña, 2014) are dealt with in separate manuscripts and are not covered here. ______________________________________________________________________________________________________ …”

Reference Correlations for the Viscosity and Thermal Conductivity of n-Undecane

“…In a series of recent papers, new reference correlations for the thermal conductivity of normal- and parahydrogen, 1 water, 2 SF 6 , 3 carbon dioxide, 4 toluene, 5 benzene, 6 n -pentane and iso -pentane, 7 n -hexane, 8 cyclopentane, 7 cyclohexane, 9 n -heptane, 10 methanol, 11 ethanol, 12 ethene and propene, 13 and ortho-xylene, meta-xylene, para-xylene, and ethylbenzene, 14 as well as for the viscosity of water, 15 n- hexane, 16 n -heptane, 17 benzene, 18 and toluene, 19 covering a wide range of conditions of temperature and pressure, were reported. The work was also extended to refrigerants; thus reference correlations for the thermal conductivity of R245fa 20 and R161, 21 and for the viscosity of R1234yf and R1234ze(E), 22 R245fa, 20 and R161 21 were reported.…”

Fundamental Study of Wax Deposition Under Real Flow Conditions

“…Different groups (Kashiwagi et al, 1982;Mustafa et al, 1982;Menashe and Wakeham, 1982;Nieto de Castro et al, 1983;Calado et al, 1983;Prasad and Venart, 1984;Li et al, 1984;Wada et al, 1985;Assael et al, 1987;Tanaka et al, 1988;Prasad et al, 1989;Friend and Ingham, 1991;Vesovic et al, 1994;Watanabe and Seong, 2002;Perkins et al, 2002;Holmen et al, 2002;Sun et al, 2002;Huber and Perkins, 2005;Assael et al, 2013a;Assael et al, 2013b;Le Neindre et al, 2014;Vassiliou et al, 2015;Vélez et al, 2015a;Vélez et al, 2015b;Le Neindre, 2017;Le Neindre et al, 2018) have measured thermal conductivity of liquid and gas nalkanes from methane to n-eicosane at different temperatures and pressures, mostly by the transient hot wire method. On the other hand, experimental results are scarce for heavier n-alkanes.…”