Viscosity equations of pure fluids in an innovative extended corresponding states framework

Scalabrin, G.; Cristofoli, G.; Richon, Dominique

doi:10.1016/s0378-3812(02)00008-0

Cited by 14 publications

(14 citation statements)

References 19 publications

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“…(12) with respect to all the available experimental data within the limits of validity indicated in Table V are presented in Table I; the number of the considered points for each dataset is reported in the column 'NPT range'. Tillner-Roth EoS [1] Crossover model boundary Saturation line Fig.…”

Section: Validation Of the New Thermal Conductivity Equationmentioning

confidence: 99%

“…The dashed-dotted lines represent the deviation of the conventional equation [17] with respect to Eq. (12), and for each figure, the temperature at which the two equations are compared is the mean value of the indicated range. The good performance of the new thermal conductivity equation for R152a is evidenced by Table I Error Deviation ∆ , %…”

Section: Validation Of the New Thermal Conductivity Equationmentioning

confidence: 99%

“…At given temperature and pressure inside the validity range of the crossover model, the density is calculated with both the Tillner-Roth EoS [1] and the van Pelt and Sengers model [2]; the corresponding thermal conductivity values are obtained from Eq. (12), and the error introduced by the use of the Tillner-Roth EoS is calculated with…”

Section: Consequences Of the Simplification Of The Thermodynamic Modelmentioning

confidence: 99%

“…As alternatives to the conventional procedure, some totally correlative techniques were also developed [3][4][5][8][9][10][11][12][13][14][15]. Among the others, the technique for optimizing the functional form of multiparameter equations of state, developed by Setzmann and Wagner [16], proved to be a powerful function approximator suitable to develop a transport property equation directly from the experimental data.…”

Section: Introductionmentioning

confidence: 99%

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A Multiparameter Thermal Conductivity Equation for 1,1-Difluoroethane (R152a) with an Optimized Functional Form

2006

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The application of an optimization technique to the available experimental data has led to the development of a new multiparameter equation λ = λ (T , ρ) for the representation of the thermal conductivity of 1,1-difluoroethane (R152a). The region of validity of the proposed equation covers the temperature range from 220 to 460 K and pressures up to 55 MPa, including the near-critical region. The average absolute deviation of the equation with respect to the selected 939 primary data points is 1.32%. The proposed equation represents therefore a significant improvement with respect to the literature conventional equation. The density value required by the equation is calculated at the chosen temperature and pressure conditions using a high accuracy equation of state for the fluid.

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Section: Validation Of the New Thermal Conductivity Equationmentioning

confidence: 99%

Section: Validation Of the New Thermal Conductivity Equationmentioning

confidence: 99%

Section: Consequences Of the Simplification Of The Thermodynamic Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Multiparameter Thermal Conductivity Equation for 1,1-Difluoroethane (R152a) with an Optimized Functional Form

2006

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“…Such an approach is strictly related to universal function approximators, i.e., mathematical models that express the analytical relation between dependent and independent variables directly from the experimental representation of the studied phenomenon. A number of viscosity models pertaining to this group has been developed, and they are based on multilayer feedforward neural networks [14][15][16][17][18], on a combination of the extended corresponding states and the neural networks technique [19,20], and on an optimization algorithm of the functional form [12,21].…”

Section: Introductionmentioning

confidence: 99%

A Multiparameter Viscosity Equation for 1,1-Difluoroethane (R152a) with an Optimized Functional Form

2006

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This paper presents a new formulation for the viscosity surface of 1,1-difluoroethane (R152a). The formulation is a multiparameter equation η = η (ρ, T ) obtained from an optimization technique of the functional form based on available experimental data. The equation is valid for temperatures from 240 to 440 K and pressures up to 20 MPa. Two lines of viscosity minima have been observed, and they have been analytically defined. A high accuracy equation of state for R152a was used to convert the experimental variables (P , T ) into the independent variables of the viscosity equation (ρ, T ). Comparisons with data are given to establish the accuracy of the viscosity values calculated using this equation. The obtained results are very satisfactory with an average absolute deviation of 0.27% for the selected 264 primary data points, and this is a significant improvement with respect to other equations in the literature.

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An Extended Equation of State Modeling Method II. Mixtures

et al. 2006

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This work is the extension of previous work dedicated to pure fluids. The same method is extended to the representation of thermodynamic properties of a mixture through a fundamental equation of state in terms of the Helmholtz energy. The proposed technique exploits the extended correspondingstates concept of distorting the independent variables of a dedicated equation of state for a reference fluid using suitable scale factor functions to adapt the equation to experimental data of a target system. An existing equation of state for the target mixture is used instead of an equation for the reference fluid, completely avoiding the need for a reference fluid. In particular, a Soave-Redlich-Kwong cubic equation with van der Waals mixing rules is chosen. The scale factors, which are functions of temperature, density, and mole fraction of the target mixture, are expressed in the form of a multilayer feedforward neural network, whose coefficients are regressed by minimizing a suitable objective function involving different kinds of mixture thermodynamic data. As a preliminary test, the model is applied to five binary and two ternary haloalkane mixtures, using data generated from existing dedicated equations of state for the selected mixtures. The results show that the method is robust and straightforward for the effective development of a mixturespecific equation of state directly from experimental data.

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Viscosity equations of pure fluids in an innovative extended corresponding states framework

Cited by 14 publications

References 19 publications

A Multiparameter Thermal Conductivity Equation for 1,1-Difluoroethane (R152a) with an Optimized Functional Form

A Multiparameter Thermal Conductivity Equation for 1,1-Difluoroethane (R152a) with an Optimized Functional Form

A Multiparameter Viscosity Equation for 1,1-Difluoroethane (R152a) with an Optimized Functional Form

An Extended Equation of State Modeling Method II. Mixtures

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