INVESTIGADORES
ZABALOY Marcelo Santiago
artículos
Título:
A Study of Lennard-Jones Equivalent Analytical Relationships for Modeling Viscosities
Autor/es:
M.S. ZABALOY; J.M.V. MACHADO; E.A. MACEDO
Revista:
INTERNATIONAL JOURNAL OF THERMOPHYSICS
Editorial:
SPRINGER/PLENUM PUBLISHERS
Referencias:
Lugar: New York; Año: 2001 vol. 22 p. 829 - 858
ISSN:
0195-928X
Resumen:
An analytical representation of the viscositydensitytemperature relationship of
the LennardJones (LJ) fluid, over wide ranges of temperature and density,
is critically assessed and combined with an LJ pressuredensitytemperature
equation of state to allow LJ viscosity calculations at a given temperature and
pressure. Both LJ equivalent analytical relationships (EARs) are accurate. The
potential of using an LJ-based model to represent the viscosities of real fluids
is evaluated in two steps. First, the qualitative trends generated by the two
combined LJ EARs are studied. Second, viscosity predictions for real, relatively
simple, fluids are performed. For these, it is assumed that a real fluid behaves
as an LJ fluid having a critical temperature Tc and a critical pressure Pc exactly
matching the real-fluid experimental values of Tc and Pc . Such an assumption
is equivalent to supposing that real fluids behave as LJ fluids with effective
intermolecular potential parameters consistent with the experimental critical
coordinates. The viscosity predictions are based only on molecular weight, Tc ,
and Pc . The quantitative evaluation is relative to a database of 30 relatively
simple compounds including 4 noble gases and the olefinic and aliphatic
straight-chain hydrocarbons through 8 carbon atoms. Conditions for the
evaluation ranged from 0.6 to 3 for reduced temperatures and from 0 to 3 for
LJ reduced densities. The average error is usually less than 100 for vapor and
supercritical viscosity and usually less than 250 for liquid viscosity. In its
present form, the methodology is actually a corresponding-states model where
the reference fluid is an LJ fluid.