A priori determination of the region of the three physical volume root loci in the Perturbed-Chain SAFT EOS

Alsaifi, Nayef M.; Aslani, Isa Al; Binous, Housam; Wang, Zhen‐Gang

doi:10.1016/j.fluid.2016.11.023

Cited by 10 publications

(36 citation statements)

References 32 publications

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“…We point out that the increase of pressure may display other spurious two‐phase separation regions as a result of the combination of the physical and unphysical branches 34,35 . In a previous article, 35 we critically evaluated the unphysical behavior in the so‐called statistical association fluid theory (SAFT), which is an equation of state developed for spherical and nonspherical molecules.…”

Section: Discussionmentioning

confidence: 99%

“…The solution of the differential algebraic system needs an arbitrary initial condition ( T ( s = 0), V ( s = 0)), which is obtained by determining a volume root at selected temperature and pressure. More details of the numerical analysis were given in our previous work 34,35 …”

Section: Overview Of Bifurcation Analysismentioning

confidence: 99%

“…In the subsequent discussions, any isobar similar to the one given in Figure 1b is designated by physical branch. Unfortunately, the deterioration of the S‐shaped branch is common in equations of state 34,35 . As will be illustrated later, some equations of state display its physical branch with eight turning points.…”

Section: Overview Of Bifurcation Analysismentioning

confidence: 99%

“…In fact, there is evidence to support such a conclusion because some of these equations have already been successfully utilized in some practical applications 2,30‐33 . Irrespective of this success, experience has shown that limitations and defects of equations of state usually become fully apparent after years of extensive usage 34‐36 . It is actually hard to anticipate a model with arbitrary empirical analytical expressions without any sort of erroneous behaviors 35 .…”

Section: Introductionmentioning

confidence: 99%

“…Recently, we have developed a new technique to probe the prediction of theory‐based equations of state using concepts from bifurcation theory 34,35 . The technique tracks the evolution of volume roots (V) as temperatures (T) vary at constant pressure (P).…”

Section: Introductionmentioning

confidence: 99%

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Simulation‐based equations of state for the Lennard‐Jones fluid: Apparent success and hidden failure

Alsaifi

2020

AIChE Journal

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In this work, we utilize concepts from bifurcation theory to pinpoint hidden defects in accurate multiparameter simulation‐based equations of state for the Lennard‐Jones (LJ) fluid. The proposed bifurcation diagrams track the evolution of volume roots as temperatures vary at constant pressure. We critically evaluate four distinct types of LJ‐based equations of state: modified Benedict‐Webb‐Rubin equation (with three different parameter sets), Kolafa and Nezbeda, Mecke et al, and Thol et al. For each model, we mainly construct two bifurcation diagrams at subcritical and supercritical isobars. The unphysical behaviors associated with the studied equations involve spurious two‐phase separation regions, distorted volume‐temperature behavior, unphysical branches, unphysical turning points, and multiplicity in volume roots. Our proposed bifurcation diagram provides a reliable and simple technique to pinpoint hidden defects in equations of state‐based merely on temperature, volume, and pressure without the need of their partial derivatives or thermodynamic potentials.

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Section: Discussionmentioning

confidence: 99%

Section: Overview Of Bifurcation Analysismentioning

confidence: 99%

Section: Overview Of Bifurcation Analysismentioning

confidence: 99%