Molecular thermodynamics of continuous mixtures

Briano, Julio G.; Glandt, Eduardo D.

doi:10.1016/0378-3812(83)80117-4

Cited by 61 publications

(24 citation statements)

References 8 publications

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“…Other derivations and applications are described by Bowman and Edmister, 19 Edmister and Bowman, 20 and Briano and Glandt. 21 The CT theory is based on the appropriate representation of the chemical potential for a mixture containing numerous components and uses molecular thermodynamic methods to represent the Gibbs function in terms of the probability distribution function ͑PDF͒ describing the mixture composition. The concepts are fundamental and independent of the physicochemical model chosen to represent the chemical potential.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulation of a transitional temporal mixing layer laden with multicomponent-fuel evaporating drops using continuous thermodynamics

Clercq

Bellan

2004

Physics of Fluids

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A model of a temporal three-dimensional mixing layer laden with fuel drops of a liquid containing a large number of species is derived. The fuel model is based on continuous thermodynamics, whereby the composition is statistically described through a distribution function parametrized on the species molar weight. The drop temperature is initially lower than that of the carrier gas, leading to drop heat up and evaporation. The model describing the changes in the multicomponent ͑MC͒ fuel drop composition and in the gas phase composition due to evaporation encompasses only two more conservation equations when compared with the equivalent single-component ͑SC͒ fuel formulation. Single drop results of a MC fuel having a sharply peaked distribution are shown to compare favorably with a validated SC-fuel drop simulation. Then, single drop comparisons are performed between results from MC fuel and a representative SC fuel used as a surrogate of the MC fuel. Further, two mixing layer simulations are conducted with a MC fuel and they are compared to representative SC-fuel simulations conducted elsewhere. Examination of the results shows that although the global layer characteristics are generally similar in the SC and MC situations, the MC layers display a higher momentum-thickness-based Reynolds number at transition. Vorticity analysis shows that the SC layers exhibit larger vortical activity than their MC counterpart. An examination of the drop organization at transition shows more structure and an increased drop-number density for MC simulations in regions of moderate and high strain. These results are primarily attributed to the slower evaporation of MC-fuel drops than of their SC counterpart. This slower evaporation is due to the lower volatility of the higher molar weight species, and also to condensation of already-evaporated species on drops that are transported in regions of different gas composition. The more volatile species released in the gas phase earlier during the drop lifetime reside in the lower stream while intermediary molar weight species, which egress after the drops are entrained in the mixing layer, reside in the mixing layer and form there a very heterogeneous mixture; the heavier species that evaporate later during the drop lifetime tend to reside in regions of high drop number density. This leads to a segregation of species in the gas phase based on the relative evaporation time from the drops. The ensemble-average drop temperature becomes eventually larger/smaller than the initial drop temperature in MC/SC simulations. Neither this species segregation nor the drop temperature variation with respect to the initial temperature or as a function of the mass loading can be captured by the SC-fuel simulations.

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Section: Introductionmentioning

confidence: 99%

Direct numerical simulation of a transitional temporal mixing layer laden with multicomponent-fuel evaporating drops using continuous thermodynamics

Clercq

Bellan

2004

Physics of Fluids

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“…4 A possibility to reduce the enormous calculation expense for a high number of components is the so-called continuous thermodynamics. [10][11][12][13] This means that instead of a discrete distribution of molar masses, a continuous distribution, over which integration can be performed, is assumed. With this method, the cloud point curves, the shadow curves (for definition see below), and the critical points of different mixtures of polydimethylsiloxane and polyethylmethylsiloxane of high polydispersity could be calculated in good agreement with experimental results.…”

Section: Theorymentioning

confidence: 99%

Phase behaviour of mixtures of polyethylene glycol and polypropylene glycol: Influence of hydrogen bond clusters on the phase diagram

Eckert

Meier

Alig

2002

Phys. Chem. Chem. Phys.

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The phase behaviour of a binary polymer blend of polyethylene glycol (PEG600) and polypropylene glycol (PPG1000) of low polydispersity was investigated. The coexistence curves of five different compositions, including the critical composition, were measured by differential refractometry. From the coexistence curves, the critical exponents of the order parameter could be determined. The order parameter of the coexistence curve of the critical composition was b ¼ 0.357, near to the Ising value. The measured coexistence curves for different compositions were different to each other and to the cloud point curve measured by small angle light scattering. These differences are explained by clusters built of intermolecular hydrogen bonds which lead to a broad effective molar mass distribution of the mixture. Two of the investigated mixtures, the mixture of critical composition (y PPG ¼ 0.46, y PPG : mass fraction of polypropylene glycol) and a mixture of non-critical composition (y PPG ¼ 0.365) were also measured by static and dynamic light scattering. The measurements were carried out in the homogeneous one-phase region (above the critical temperature T C ) and in the two-phase region in both coexisting phases. The light scattering measurements showed, additionally to the composition fluctuations due to the phase transition of demixing, a contribution of larger objects, which could be attributed to hydrogen bonded clusters. The size of these clusters was estimated to be 250 nm to 550 nm.

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“…Another advantage is the definition of C 7 þ heavier into a series of pseudocomponents based on statistical reasoning and the model parameters used to describe molar distribution [17]. A continuous description can also be used directly in EOS [18][19][20][21][22].…”

Section: Fluid Characterizationmentioning

confidence: 99%

Application of Gaussian quadrature method to characterize heavy ends of hydrocarbon fluids for modeling wax precipitation

Tabatabaei-Nejad

Khodapanah

2011

Applied Mathematical Modelling

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a b s t r a c tThe hydrocarbon plus fractions that comprise a significant portion of naturally occurring hydrocarbon fluids create major problems when determining the thermodynamic properties and the volumetric behavior of these fluids by equations of state. These problems arise due to the difficulty of properly characterizing the plus fractions (heavy ends). Proper characterization of the heavier components is important when cubic equations of state and/or solid formation thermodynamic models are used to describe complex phase behavior of reservoir fluids. The effect of heavy fractions characterization on thermodynamic modeling of wax precipitation has been investigated using different models including Won, Pan and proposed models. In order to characterize the plus fraction (heavier part) as a series of pseudocomponents, a probability model that expresses the mole fraction as a continuous function of the molecular weight has been used. The study has been conducted using several mixtures. Two different SCN (single carbon number), C 7 þ and C 10 þ were chosen. The Chosen SCN were distributed to multi-components of five, six, and/or ten using continuous function and Gaussian quadrature method. The results showed that the fractioning is required to be able to predict wax precipitation. Distribution of C 10 þ using a proper distribution function has shown improvement in predictions of WAT and the amount of wax deposited in comparison with the characterization of C 7 þ using semi-continuous approach. In predicting of WAT and the amount of wax build up the developed model showed superiority over the others.

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Molecular thermodynamics of continuous mixtures

Cited by 61 publications

References 8 publications

Direct numerical simulation of a transitional temporal mixing layer laden with multicomponent-fuel evaporating drops using continuous thermodynamics

Direct numerical simulation of a transitional temporal mixing layer laden with multicomponent-fuel evaporating drops using continuous thermodynamics

Phase behaviour of mixtures of polyethylene glycol and polypropylene glycol: Influence of hydrogen bond clusters on the phase diagram

Application of Gaussian quadrature method to characterize heavy ends of hydrocarbon fluids for modeling wax precipitation

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