A method of correlation using a search procedure, based on a step-wise least-squares technique, and its application to an equation of state for propylene

Reuck, K. M. de; Armstrong, Ben

doi:10.1016/0011-2275(79)90002-x

Cited by 61 publications

(16 citation statements)

References 5 publications

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“…(14) and (15) to fit all of the available primary data. The fitting has been performed by the use of the SEEQ algorithm based on the stepwise least-squares technique [74]. The method requires initially a bank of power indices of temperature and density from which it chooses the statistically significant terms.…”

Section: Density Dependencementioning

confidence: 99%

The transport properties of ethane. I. Viscosity

Hendl

Millat²,

Vogel

et al. 1994

Int J Thermophys

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A new representation of the viscosity of ethane is presented. The representative equations are based upon a body of experimental data that have been critically assessed for internal consistency and for agreement with theory in the zerodensity limit, vapor phase, and critical region. The representation extends over the temperature range from 100 K to the critical temperature in the liquid phase and from 200 K to the critical temperature in the vapor phase. In the supercritical region, the temperature range extends to 1000 K for pressures up to 2 MPa and to 500 K for pressures up to 60 MPa. The ascribed accuracy of the representation varies according to the thermodynamic state from _+ 0.5 % for the viscosity of the dilute gas near room temperature to +3.0% for the viscosity at high pressures and temperatures. Tables of the viscosity, generated by the relevant equations, at selected temperatures and pressures and along the saturation line, are also provided.

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Section: Density Dependencementioning

confidence: 99%

The transport properties of ethane. I. Viscosity

Hendl

Millat²,

Vogel

et al. 1994

Int J Thermophys

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“…The new terms are chosen randomly and after a certain number of tries it increases the number of terms for interchange. Three constraints at the critical point are imposed by the Lagrange multiplier (Hust and McCarty, 1967;De Reuck and Armstrong, 1979).…”

Section: S"mentioning

confidence: 99%

EQUATION OF STATE FOR 1,1-DIFLUOROETHANE (R152a)

Kim

Borgnakke

Sonntag

1997

Int. J. Energy Res.

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SUMMARYA new equation of state (EOS) for 1,1-difluoroethane (R152a) is developed in the form of the Helmholtz free energy. The EOS is valid for temperatures between 213 and 433 K (0·55(¹ P (1·12) and pressures up to 20 MPa (P P (4·4). It covers the compressed liquid, gas and two-phase regions. R152a, which does not contain any chlorine, is a potentially acceptable alternative refrigerant for chlorofluorocarbons. Chlorofluorocarbon compounds, which are widely used as refrigerants, propellants, foaming agents and cleaning agents, are known to damage the ozone layer that protects the Earth from harmful radiation. The form of the ideal gas Helmholtz free energy is obtained from statistical thermodynamics, and the residual part is determined from experimental data. From a bank of terms that are suggested, an optimum set of terms is selected by a random search method. The results are compared with the experimental data, and tables of the thermodynamic properties of R152a are presented.

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“…(8) is a linear stepwise regression incorporating a search procedure based on statistical parameters monitored during the fitting procedure. This algorithm was developed by Wagner [72] and further modified for equations of state by de Reuck and Armstrong [73]. It is capable of simultaneously BIAS=-V (%AA,I (111…”

Section: The Fundamental Equation For Cyclohexane the Functional Formmentioning

confidence: 99%

A thermodynamic property formulation for cyclohexane

1995

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A Ibrmt, lation for the thermodynanlic properties of cyclohexane is presented. The equation is valid for single-phase and saturation states from the melting line to 700 K at pressures up to 80 MPa. It includes aft, ndamental equation explicit in reduced Hel,nholtz energy with independent variables of reduced density and temperature. The functional form and coefficients of the ancillary equations were determined by weighted linear regression analyses of evahmted experimental data. An adaptive regression algorithm was t, sed to determine the final eqt,atinn. To ensure correct thermodynanlic behavior of the Helmholtz energy surface, the coefficients of the fundamental equation were determined with multiproperty fitting. Pressure-density-temperature I P-p-T} and isobaric heat capacity [C~, P-TI data were used to develop the fundamental equation. Saturation P-p-T valt, es, calculated from the estimating functions, were used to enst, re thermodynamic consistency at the wlpor-liquid phase boundary. Separate fnnctions were used for the vapor pressure, satt, rated liquid density, satt, rated vapor density, ideal-gas heat capacity, and pressure on the melting curve. Comp~,risons between experimental dat~, and values calculated using the fundamental equation are given to verify the accuracy of the formulation. The formulation given here may be used to calculate densities within +0.1 °~,b, heat capacities to within +2"/0. and speed of sound to within + I%, except near the critical point.

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A method of correlation using a search procedure, based on a step-wise least-squares technique, and its application to an equation of state for propylene

Cited by 61 publications

References 5 publications

The transport properties of ethane. I. Viscosity

The transport properties of ethane. I. Viscosity

EQUATION OF STATE FOR 1,1-DIFLUOROETHANE (R152a)

A thermodynamic property formulation for cyclohexane

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