Thermodynamic models to accurately describe the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mrow><mml:mi>P</mml:mi><mml:mi>V</mml:mi><mml:mi>T</mml:mi><mml:mi>x</mml:mi><mml:mi>y</mml:mi></mml:mrow></mml:math>-behavior of water / carbon dioxide mixtures

Aasen, Ailo; Hammer, Morten; Skaugen, Geir; Jakobsen, Jana P.; Wilhelmsen, Øivind

doi:10.1016/j.fluid.2017.02.006

Cited by 49 publications

(65 citation statements)

References 84 publications

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“…16, and we refer to previous work for details on routines for solving phase equilibria. [43][44][45][46] A. Details on the numerics in the solution of SAFT-VRQ Mie…”

Section: Methodsmentioning

confidence: 99%

Equation of state and force fields for Feynman–Hibbs-corrected Mie fluids. I. Application to pure helium, neon, hydrogen, and deuterium

Aasen

Hammer

Ervik

et al. 2019

The Journal of Chemical Physics

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We present a perturbation theory that combines the use of a third-order Barker–Henderson expansion of the Helmholtz energy with Mie-potentials that include first- (Mie-FH1) and second-order (Mie-FH2) Feynman–Hibbs quantum corrections. The resulting equation of state, the statistical associating fluid theory for Mie potentials of variable range corrected for quantum effects (SAFT-VRQ-Mie), is compared to molecular simulations and is seen to reproduce the thermodynamic properties of generic Mie-FH1 and Mie-FH2 fluids accurately. SAFT-VRQ Mie is exploited to obtain optimal parameters for the intermolecular potentials of neon, helium, deuterium, ortho-, para-, and normal-hydrogen for the Mie-FH1 and Mie-FH2 formulations. For helium, hydrogen, and deuterium, the use of either the first- or second-order corrections yields significantly higher accuracy in the representation of supercritical densities, heat capacities, and speed of sounds when compared to classical Mie fluids, although the Mie-FH2 is slightly more accurate than Mie-FH1 for supercritical properties. The Mie-FH1 potential is recommended for most of the fluids since it yields a more accurate representation of the pure-component phase equilibria and extrapolates better to low temperatures. Notwithstanding, for helium, where the quantum effects are largest, we find that none of the potentials give an accurate representation of the entire phase envelope, and its thermodynamic properties are represented accurately only at temperatures above 20 K. Overall, supercritical heat capacities are well represented, with some deviations from experiments seen in the liquid phase region for helium and hydrogen.

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“…16, and we refer to previous work for details on routines for solving phase equilibria. [43][44][45][46] A. Details on the numerics in the solution of SAFT-VRQ Mie…”

Section: Methodsmentioning

confidence: 99%

Equation of state and force fields for Feynman–Hibbs-corrected Mie fluids. I. Application to pure helium, neon, hydrogen, and deuterium

Aasen

Hammer

Ervik

et al. 2019

The Journal of Chemical Physics

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“…Corresponding state principles (CSPs) using different reference equations were also investigated, as were multi-parameter high accuracy EOSs. Details of the different categories of the EOSs, and their implementation, can be reviewed in [14]. Details about the CSP EOSs are explained by Ibrahim et al [15].…”

Section: Methodsmentioning

confidence: 99%

Analysis of Thermodynamic Models for Simulation and Optimisation of Organic Rankine Cycles

Durakovic

Skaugen

2019

Energies

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Equations of state (EOSs) form the base of every thermodynamic model used in the design of industrial processes, but little work has been done to evaluate these in the context of such models. This work evaluates 13 EOSs for their accuracy, computational time and robustness when used in an in-house optimisation program that finds the maximum power output of an organic Rankine cycle. The EOSs represent popular choices in the industry, such as the simple cubic EOSs, and more complex EOSs such as the ones based on corresponding state principles (CSP). These results were compared with results from using the Groupe Européen de Recherches Gazières (GERG) EOS, whose error is within experimental uncertainty. It appears that the corresponding state EOSs find a solution to the optimisation problem notably faster than GERG without significant loss of accuracy. A corresponding state method which used the Peng–Robinson EOS to calculate the shape factors and a highly accurate EOS for propane as the reference EOS, was shown to have a total deviation of just 0.6% as compared to GERG while also being 10 times as fast. The CSP implementation was also more robust, being able to converge successfully more often.

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“…If the virial expansion is truncated at the m th term, applying Eq. (14) to Eq. (34) gives which is a polynomial equation in the density.…”

Section: The Virial Expansionmentioning

confidence: 99%

“…(36) yield {T, n} sets, which can be converted into {T, P } using Eq. (14). The JT inversion curve computed from the virial expansion is compared with MD results in Figure 11.…”

Section: The Virial Expansionmentioning

confidence: 99%

“…Since van der Waals' pioneering work on EoS at the end of the 19th century [9], the field has developed much and branched into different types of EoS, where each type has its advantages and disadvantages. Cubic EoS, such as Peng-Robinson [10] and Soave-Redlich-Kwong [11], possibly with advanced mixing rules [12,13] are used extensively in process simulations, time-consuming optimisation studies, and solubility predictions [14,15]. The accuracy of cubic EoS are limited by their simple form, and they are known to give poor predictions of the liquid-phase densities.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic properties of the 3D Lennard-Jones/spline model

et al. 2019

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In the Lennard-Jones spline (LJ/s) model, the Lennard-Jones (LJ) potential is truncated and splined so that both the pair potential and the force continuously approach zero at rc ≈ 1.74σ. It exhibits the same structural features as the LJ model, but the thermodynamic properties are different due to the shorter range of the potential. One advantage of the model is that simulation times are much shorter. In this work, we present a systematic map of the thermodynamic properties of the LJ/s model from molecular dynamics and Gibbs ensemble Monte Carlo simulations. Accurate results are presented for gas/liquid, liquid/solid and gas/solid coexistence curves, supercritical isotherms up to a reduced temperature of 2 (in LJ units), surface tensions, speed of sound, the Joule-Thomson inversion curve, and the second to fourth virial coefficients. The critical point for the LJ/s model is estimated to be T * c = 0.885 ± 0.002 and P * c = 0.075 ± 0.001, respectively. The triple point is estimated to T * tp = 0.547 ± 0.005 and P * tp = 0.0016 ± 0.0002. Despite the simplicity of the model, the acentric factor was found to be as large as 0.07±0.02. The coexistence densities, saturation pressure, and supercritical isotherms of the LJ/s model were fairly well represented by the Peng-Robison equation of state. We find that Barker-Henderson perturbation theory works much more poorly for the LJ/s model than for the LJ model. The first-order perturbation theory overestimates the critical temperature and pressure by about 10% and 90%, respectively. A second-order perturbation theory that uses the mean compressibility approximation shifts the critical point closer to simulation data, but makes the prediction of the saturation densities worse. It is hypothesized that the reason for this is that the mean compressibility approximation gives a poor representation of the second-order perturbation term for the LJ/s model and that a correction factor is needed at high densities.Our main conclusion is that we at the moment do not have a theory or model that adequately represents the thermodynamic properties of the LJ/s system.

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Thermodynamic models to accurately describe thePVTxy-behavior of water / carbon dioxide mixtures

Cited by 49 publications

References 84 publications

Equation of state and force fields for Feynman–Hibbs-corrected Mie fluids. I. Application to pure helium, neon, hydrogen, and deuterium

Equation of state and force fields for Feynman–Hibbs-corrected Mie fluids. I. Application to pure helium, neon, hydrogen, and deuterium

Analysis of Thermodynamic Models for Simulation and Optimisation of Organic Rankine Cycles

Thermodynamic properties of the 3D Lennard-Jones/spline model

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