A generalized B‐W‐R equation of state

Two forms of a generalized Benedict-Webb-Rubin Equation, BWR24 and BWR44, are proposed for dense gases which represent an improvement by a factor of about three in calculated pressures compared to reduced forms of this relationship in the literature. The method is also tested for accuracy in predicting enthalpy departures for pure components and mixtures. The proposed methods are marginally better than the best of other methods tested. Major advantages for the proposed equations are their relative simplicity, low computer storage requirements, and generality. No mixture interaction constants are required other than those already available in the literature.

Section: Discussionmentioning

confidence: 99%

“…The reduced form of the BWR Equation used here is identical with that used previously %y Edmister et al (1968).…”

Section: Generalization Of the Bwr Equationmentioning

confidence: 99%

Section: Scopementioning

confidence: 99%

Section: Enthalpy Departuresmentioning

confidence: 99%

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An improved generalized equation of state

Yamada

1973

“…Part of the experimental compressibility factors are shown in Table 3 Eakin and Ellington (7). The generalized constants for the B-W-R equations were calculated by using critical properties and the acentric factor (8,11). The deviations between the empirical equations of state and the experimental data are summarized in Table 3.…”

Section: Derived Z Valuesmentioning

confidence: 99%

Compressibilities and virial coefficients for methane, ethylene, and their mixtures

Lee

Edmister

1970

t = local temperature T u = local axial velocity U = dimensionless velocity, u/Uc U,,, = average fluid velocity in axial direction U , U,,,,, = maximum local velocity in axial direction a = disturbance wave number fl p = liquid viscosity p = liquiddensity c w = dimensionless temperature, t,t/t,tc = fluid velocity at pipe center in axial direction = coefficient of volumetric expansion= quantity evaluated at R = 0 = quantityevaluatedat R = 1 A Burnett type of apparatus was built for 12,000 Ib./sq.in. pressure and temperatures of 25" to 100°C. Isothermal expansions were run on methane, ethylene, and four binary mixtures a t 25", 50°, and 75"C., and compressibility factors were derived from the pressure ratio R. C. Lee is presently at

The experimental determination of the volumetric properties and virial coefficients of the methane‐ethylene system

McMath

Edmister

1969

For the case when x # 0, the substitution of Equation (A8) into Equation ( A 6 ) yieldsFurthermore, this equation can be written as Without loss of generality the arbitrary constant, C1, can be set equal to one. Then, the substitution of Equation (A8) into Equation (A4) with the relation, Equation (A5), gives the similarity transformation, Equation ( 7 ) , and Equation (A10) becomes Equation ( 8 ) . Similarly, the transformed boundary conditions for Equations (A2) and ( A 3 ) are those given in Equations ( 9 ) Volumetric (or compressibility factor) data are of industrial interest in process design calculations. The data are also of value in the calculation of derived thermodynamic quantities and in the further development of generalized methods for estimating thermodynamic properties from a minimum of direct data.In the past, several experimental facilities have been developed for determining compressibility factors of mixtures or pure components along isochoric (constant density) paths. The apparatus of Goodwin ( 7 ) , Michels (16, 2 0 ) , and Solbrig and Ellington ( 2 8 ) are of the isochoric type. In principle the compressibility factors for a constant composition system become established with the simultaneous knowledge of the three quantities pressure, temperature, and density. At selected points along an isochoric path the pressure and temperature are directly measured, and the data thus consist of a series of P-T points at constant density. The value of the density may be determined by separate measurement of the mass and volume quantities or, alternately, the density may be determined from the previously measured compressibility factors of the sample at a reference temperature.In the apparatus described herein, the density of the sample is determined from the compressibility factors along the reference isotherm (77°F.). The isotherm is independently determined using a Burnett type of apparatus ( 3 ) .The methane-ethylene binary system was selected for this study. The compressibility factors of the methane system have been extensively reported from -274 to 650°F.