huber_2018
==========

M\. L\. Huber, "Models for Viscosity, Thermal Conductivity, and Surface Tension of Selected Pure Fluids as Implemented in REFPROP v10\.0", NIST Interagency Report 8209 \(2018\)

`Source record <https://github.com/LupoLab/optmat/blob/main/src/optmat/data/sources/huber_2018.toml>`__ · :doc:`Catalogue </the-data/sources>` · :doc:`Review register </register>`

DOI: `10\.6028/nist\.ir\.8209 <https://doi.org/10.6028/nist.ir.8209>`__

**Source kind:** fit

**Recorded technique:** The transport models of REFPROP 10 for fluids without a reference correlation\: extended corresponding states with a reference fluid \(nitrogen for the four gases here\), whose dilute\-gas viscosity is Chapman\-Enskog theory with a Lennard\-Jones collision integral and a correction factor F\_c fitted, per fluid, to dilute\-gas data\. The NIST Chemistry WebBook \(SRD 69\) evaluates these models\.

**Materials in structured entries:** Kr, N2O, Ne, Xe

**Dataset quantities:** None recorded.

**Contents:** 0 datasets; 4 formulas.

Curation notes
--------------

Identity VALIDATED by the library\. Pages are the report's pdf pages\.

THE DILUTE\-GAS VISCOSITY \(pdf p\. 9\)\: Eq\. \(6\), eta\* = 5 sqrt\(m pi k\_B T\) / \(16 pi sigma^2 Omega\(2,2\)\); Eq\. \(7\), Neufeld et al\.'s collision integral without its sinusoidal term, Omega\(2,2\) = 1\.16145 T\*^\-0\.14874 \+ 0\.52487 exp\(\-0\.77320 T\*\) \+ 2\.16178 exp\(\-2\.43787 T\*\), valid for 0\.3 \< T\* \< 100, T\* = k\_B T/epsilon; the dilute viscosity is eta\* times F\_c\. Table 1 \(pdf p\. 262\)\: neon M = 20\.179 g/mol, epsilon/k\_B = 45\.58 K, sigma = 0\.2707 nm; krypton 83\.798, 178\.9 K, 0\.3655 nm; xenon 131\.293, 260\.91 K, 0\.3929 nm; nitrous oxide 44\.0128, 232\.4 K, 0\.3828 nm\. Table 2 \(pdf p\. 265\)\: F\_c = 0\.989544 \(neon\), 1\.008291 \(krypton\), 1\.0012 \(xenon\), 1 \(nitrous oxide\), each with nitrogen as the reference fluid\. All read from the library's tables and text, 2026\-09\-30\.

THE CONSTANT\. Table 7's check values of eta\* \(pdf p\. 274\: neon 6\.006075 uPa s at 40 K, krypton 16\.32999 at 188\.5 K, xenon 20\.11099 at 260\.8 K, nitrous oxide 13\.86694 at 278\.6 K\) are reproduced to 2\.4e\-7 by eta\* = 0\.026692 sqrt\(M T\)/\(sigma^2 Omega\) uPa s \(M in g/mol, sigma in nm\), REFPROP's constant; Eq\. \(6\) with CODATA's k\_B gives 1\.38e\-4 more \(computed 2026\-09\-30\)\. optmat uses 0\.026692, the report's own check values and the WebBook's tables; the difference is far below every stated uncertainty\.

F\_c\. For neon, krypton and xenon F\_c was adjusted so that the dilute\-gas viscosity at 25 C and 0\.1 MPa agrees with the reference values of Assael et al\. \(2018\) \(sections 6\.9\.1\-6\.9\.3\), which are therefore not an independent check\. For nitrous oxide F\_c = 1\.

UNCERTAINTY \(expanded, coverage factor two, 'approximately a 95 % confidence interval', pdf p\. 14\)\: neon, 2 % in the supercritical region at atmospheric pressure \(section 6\.9\.1, pdf p\. 185\); krypton, 3 % in the gas phase at atmospheric pressure \(6\.9\.2, p\. 188\); xenon, 0\.7 % in the vapour phase \(6\.9\.3, p\. 191\); nitrous oxide, 5 % in the gas phase \(6\.11\.2, p\. 201\)\. The WebBook's pages state 3 %, 3 %, 1 % and 10 % for the same models; the report governs\. optmat takes each gas's equation\-of\-state temperatures within Eq\. \(7\)'s 0\.3 \< T\* \< 100\.

THE WEBBOOK TABLES \(data/external/nist\_webbook, captured 2026\-09\-30\) give the models' viscosity at 0\.1 MPa, 200\-400 K\: they exceed the dilute values by 0\.013 % \(neon\), 0\.13 % \(krypton\), 0\.21 % \(xenon\) and 0\.21 % \(nitrous oxide\) at 298\.15 K, and by 0\.028 %, 0\.33 %, 0\.54 % and 0\.52 % at 200 K, the density term, falling with temperature \(tests/test\_transport\.py\)\.

**Recorded bibliographic identity status:** VALIDATED. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets
--------

No datasets are recorded.

Formulas
--------

huber\_2018/eq6\_eq7\_Ne
~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "eq6_eq7_Ne",
     "material": "Ne",
     "equation": "Eqs. (6)-(7), pdf p. 9; Tables 1-2, pdf pp. 262, 265",
     "printed": "eta* = 5 sqrt(m pi k_B T)/(16 pi sigma^2 Omega(2,2)) F_c; Omega(2,2) = 1.16145 T*^-0.14874 + 0.52487 exp(-0.77320 T*) + 2.16178 exp(-2.43787 T*)",
     "variable": "T* = k_B T/epsilon, 0.3 < T* < 100; eta* = 0.026692 sqrt(M T)/(sigma^2 Omega) F_c in uPa s, M in g/mol, sigma in nm",
     "range": "0.3 < T* < 100",
     "coefficients": {
       "prefactor": "0.026692",
       "molar_mass": "20.179",
       "epsilon_k": "45.58",
       "sigma_nm": "0.2707",
       "f_c": "0.989544"
     },
     "check": "Table 7: 6.006075 uPa s at 40 K, reproduced to 6e-8."
   }

huber\_2018/eq6\_eq7\_Kr
~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "eq6_eq7_Kr",
     "material": "Kr",
     "equation": "Eqs. (6)-(7), pdf p. 9; Tables 1-2, pdf pp. 262, 265",
     "printed": "eta* = 5 sqrt(m pi k_B T)/(16 pi sigma^2 Omega(2,2)) F_c; Omega(2,2) = 1.16145 T*^-0.14874 + 0.52487 exp(-0.77320 T*) + 2.16178 exp(-2.43787 T*)",
     "variable": "T* = k_B T/epsilon, 0.3 < T* < 100; eta* = 0.026692 sqrt(M T)/(sigma^2 Omega) F_c in uPa s, M in g/mol, sigma in nm",
     "range": "0.3 < T* < 100",
     "coefficients": {
       "prefactor": "0.026692",
       "molar_mass": "83.798",
       "epsilon_k": "178.9",
       "sigma_nm": "0.3655",
       "f_c": "1.008291"
     },
     "check": "Table 7: 16.32999 uPa s at 188.5 K, reproduced to 1.7e-7."
   }

huber\_2018/eq6\_eq7\_Xe
~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "eq6_eq7_Xe",
     "material": "Xe",
     "equation": "Eqs. (6)-(7), pdf p. 9; Tables 1-2, pdf pp. 262, 265",
     "printed": "eta* = 5 sqrt(m pi k_B T)/(16 pi sigma^2 Omega(2,2)) F_c; Omega(2,2) = 1.16145 T*^-0.14874 + 0.52487 exp(-0.77320 T*) + 2.16178 exp(-2.43787 T*)",
     "variable": "T* = k_B T/epsilon, 0.3 < T* < 100; eta* = 0.026692 sqrt(M T)/(sigma^2 Omega) F_c in uPa s, M in g/mol, sigma in nm",
     "range": "0.3 < T* < 100",
     "coefficients": {
       "prefactor": "0.026692",
       "molar_mass": "131.293",
       "epsilon_k": "260.91",
       "sigma_nm": "0.3929",
       "f_c": "1.0012"
     },
     "check": "Table 7: 20.11099 uPa s at 260.8 K, reproduced to 2.4e-7."
   }

huber\_2018/eq6\_eq7\_N2O
~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "eq6_eq7_N2O",
     "material": "N2O",
     "equation": "Eqs. (6)-(7), pdf p. 9; Tables 1-2, pdf pp. 262, 265",
     "printed": "eta* = 5 sqrt(m pi k_B T)/(16 pi sigma^2 Omega(2,2)) F_c; Omega(2,2) = 1.16145 T*^-0.14874 + 0.52487 exp(-0.77320 T*) + 2.16178 exp(-2.43787 T*)",
     "variable": "T* = k_B T/epsilon, 0.3 < T* < 100; eta* = 0.026692 sqrt(M T)/(sigma^2 Omega) F_c in uPa s, M in g/mol, sigma in nm",
     "range": "0.3 < T* < 100",
     "coefficients": {
       "prefactor": "0.026692",
       "molar_mass": "44.0128",
       "epsilon_k": "232.4",
       "sigma_nm": "0.3828",
       "f_c": "1"
     },
     "check": "Table 7: 13.86694 uPa s at 278.6 K, reproduced to 2e-8."
   }

Corrections
-----------

No dataset errata are recorded in this source record.

Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the :doc:`review register </register>` for the checks and decisions.