Title and Link to Calc:

Fluid Properties : Redlich-Kwong Equation of State : FP-VANN-0019

Description:

Calculates gas state molar volumes per the Redlich-Kwong (RK) equation of state and per the ideal gas law. The RK constants are generated from the critical parameters (temperature and pressure) that are required as inputs.

Alternative Descriptors:

Molar Specific volumes per Redlich-Kwong equation of state, Molar specific volume per ideal gas law, Compressibility, Mass specific volumes, Generalized Redlich-Kwong based on critical state - critical temperature and critical pressure

Calc Number:

FP-VANN-0019

Calc Status:

Beta

Reference:

Introduction to Chemical Engineering Thermodynamics, 3rd Edition, Smith & Van Ness, pgs. 93-94

Reference Example(s) Modeled/Generalized:

Example 3-8 of the above reference

Calc Origination Date:

03/04/2006

Calc Originator:

RBC

Calc Revision History:

Calc Guidelines:

See the above reference

Access:

Activating this calc requires entry of the correct access code. Contact eng-calc@eng-calcs.com

Variables:

Variable Description - Description of the variable
Variable Label Description - The description of the variable as it appears in the calc.
Variable Calc Name - The calc internal variable name
Variable Units - The units for the variable
Variable Calc Upper Limit - The highest allowed value in the calc.
Variable Calc Lower Limit - The lowest allowed value in the calc.
Variable Type - Either "Output" or "Input"
Variable Format - Real Number, Text, or Integer
Variable Notes - Other comments about the variable

Variable Description: Molar specific volume in cubic feet per pound-mole based on RK equation of state
Variable Label Description: RK Molar Specific Volume
Variable Calc Name: RKMO
Variable Units: CUFT/LBMOL
Variable Calc Upper Limit: 100000
Variable Calc Lower Limit: 0
Variable Type: Output
Variable Format: REAL
Variable Notes:

Variable Description: Molar specific volume in cubic feet per pound-mole based on Ideal Gas Law
Variable Label Description: Ideal Molar Specific Volume
Variable Calc Name: IDMO
Variable Units: CUFT/LBMOL
Variable Calc Upper Limit: 100000
Variable Calc Lower Limit: 0
Variable Type: Output
Variable Format: REAL
Variable Notes:

Variable Description: Mass specific volume in cubic feet per pound based on RK equation of state an input molecular weight
Variable Label Description: RK Mass Specific Volume
Variable Calc Name: RKMA
Variable Units: CUFT/LBM
Variable Calc Upper Limit: 100000
Variable Calc Lower Limit: 0
Variable Type: Output
Variable Format: REAL
Variable Notes:

Variable Description: Mass specific volume in cubic feet per pound based on ideal gas law an input molecular weight
Variable Label Description: Ideal Mass Specific Volume
Variable Calc Name: IDMA
Variable Units: CUFT/LBM
Variable Calc Upper Limit: 100000
Variable Calc Lower Limit: 0
Variable Type: Output
Variable Format: REAL
Variable Notes:

Variable Description: Compressibility Factor at input temperature and pressure based on Redlich-Kwong equation of state
Variable Label Description: RK Compressibility Factor
Variable Calc Name: ZCOM
Variable Units:
Variable Calc Upper Limit: 2
Variable Calc Lower Limit: 0
Variable Type: Output
Variable Format: REAL
Variable Notes: Calc searches for this value by first using the successive substitution (SS) algorithm suggested in the reference. If this fails, then the calc starts at ZCOM=2.0 and searches downward (brute force) until it finds an apparent solution. It does not look for additional values. If the SS algorithm fails, then the comment line displays "SS Convergence Failed.". If the brute force algorithm fails, then "Brute Force Search Failed" is also displayed and the RK values in the output lines are invalid.

Variable Description: Comments
Variable Label Description: Comments
Variable Calc Name: COM
Variable Units:
Variable Calc Upper Limit:
Variable Calc Lower Limit:
Variable Type: Output
Variable Format: TEXT
Variable Notes: Displays "Input(s) out of range." if an entered input variable(s) are out of range. Displays "Output(s) out of range." if an output variable exceeds its range. The "out of range" variable(s) are displayed in yellow. The limited range values are used in the calculation, not the "out of range" value(s). Displays "Multiple roots found." when there are multiple roots to the cubic equation. Displays "One root found. " when there is only one root ot the cubic equation.

Variable Description: Pressure of Fluid in PSIA
Variable Label Description: Fluid Pressure
Variable Calc Name: PRES
Variable Units: PSIA
Variable Calc Upper Limit: 20000
Variable Calc Lower Limit: 0.001
Variable Type: Input
Variable Format: REAL
Variable Notes:

Variable Description: Temp of Fluid in Rankine
Variable Label Description: Fluid Temperature
Variable Calc Name: TEMP
Variable Units: R
Variable Calc Upper Limit: 20000
Variable Calc Lower Limit: 0.001
Variable Type: Input
Variable Format: REAL
Variable Notes:

Variable Description: Molecular Weight of fluid
Variable Label Description: Fluid Molecular Weight
Variable Calc Name: MW
Variable Units:
Variable Calc Upper Limit: 20000
Variable Calc Lower Limit: 0.001
Variable Type: Input
Variable Format: REAL
Variable Notes:

Variable Description: Critical Pressure of Fluid in PSIA
Variable Label Description: Fluid Critical Pressure
Variable Calc Name: CPRE
Variable Units: PSIA
Variable Calc Upper Limit: 20000
Variable Calc Lower Limit: 0.001
Variable Type: Input
Variable Format: REAL
Variable Notes:

Variable Description: Critical Temperature of Fluid in Rankine
Variable Label Description: Fluid Critical Temperature
Variable Calc Name: CTEM
Variable Units: R
Variable Calc Upper Limit: 20000
Variable Calc Lower Limit: 0.001
Variable Type: Input
Variable Format: REAL
Variable Notes:

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