Class TBPfractionModel.CavettModel

java.lang.Object

neqsim.thermo.characterization.TBPfractionModel.TBPBaseModel

neqsim.thermo.characterization.TBPfractionModel.CavettModel

All Implemented Interfaces:

Serializable, Cloneable, TBPModelInterface

Enclosing class:

TBPfractionModel

public class TBPfractionModel.CavettModel
extends TBPfractionModel.TBPBaseModel

Cavett (1962) property estimation method with Lee-Kesler enhancements.

This implementation combines the Cavett API gravity corrections with the more robust Lee-Kesler correlations for improved accuracy across a wider range of petroleum fractions. The original Cavett correlations are known to have issues with light fractions (C7-C10), so this hybrid approach uses Lee-Kesler as the base with API gravity adjustments.

Key Features:

• Hybrid Lee-Kesler/Cavett approach for robustness
• API gravity corrections for heavy fractions (API < 30°)
• Riazi-Daubert boiling point correlation
• Edmister acentric factor with bounds checking

Correlations:

Critical Temperature (Lee-Kesler base with API correction):

T_c = [189.8 + 450.6·SG + (0.4244 + 0.1174·SG)·T_b + (0.1441 - 1.0069·SG)·10⁵/T_b] × f(API)

where f(API) = 1 + 0.002·(30 - API) for API < 30°, otherwise f(API) = 1

Critical Pressure (Lee-Kesler base with API correction):

ln(P_c) = 3.3864 - 0.0566/SG - g(T_b, SG) with API correction

Acentric Factor (Edmister):

ω = (3/7) × log₁₀(P_c/P_ref) / (T_c/T_b - 1) - 1

Bounded to range [0.0, 1.5] for physical validity

API Gravity Relationship:

API = 141.5/SG - 131.5

• API > 31.1°: Light crude (SG < 0.87)
• API 22.3-31.1°: Medium crude
• API < 22.3°: Heavy crude (SG > 0.92)

Recommended Applications:

• Refining industry calculations
• Heavy oil characterization (API < 30°)
• When API gravity data is available and important

Reference: Cavett, R.H. (1962). "Physical Data for Distillation Calculations, Vapor-Liquid Equilibria." Proc. 27th API Meeting, San Francisco.

Version:

$Id: $Id

Author:

ESOL

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private static final long	serialVersionUID	Serialization version UID.

Fields inherited from class TBPfractionModel.TBPBaseModel

calcm

Constructor Summary

Constructors

Constructor	Description
CavettModel()

Method Summary

Modifier and Type	Method	Description
double	calcAcentricFactor(double molarMass, double density)	Calculate acentric factor using Edmister correlation.
private double	calcAPI(double sg)	Calculate API gravity from specific gravity.
double	calcPC(double molarMass, double density)	Calculate critical pressure using Lee-Kesler correlation with API correction.
double	calcRacketZ(SystemInterface thermoSystem, double molarMass, double density)	calcRacketZ.
double	calcTB(double molarMass, double density)	Calculate boiling point using Riazi-Daubert correlation.
double	calcTC(double molarMass, double density)	Calculate critical temperature using Lee-Kesler correlation with API correction.

Methods inherited from class TBPfractionModel.TBPBaseModel

calcAcentricFactorKeslerLee, calcCriticalViscosity, calcCriticalVolume, calcm, calcParachorParameter, calcWatsonCharacterizationFactor, getBoilingPoint, getName, isCalcm, setBoilingPoint

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

serialVersionUID

private static final long serialVersionUID

Serialization version UID.

See Also:

• Constant Field Values

Constructor Details

CavettModel

public CavettModel()

Method Details

calcAPI

private double calcAPI(double sg)

Calculate API gravity from specific gravity.

Parameters:

sg - specific gravity (water = 1.0)

Returns:

API gravity in degrees

calcTB

public double calcTB(double molarMass,
 double density)

Calculate boiling point using Riazi-Daubert correlation.

Specified by:

calcTB in interface TBPModelInterface

Overrides:

calcTB in class TBPfractionModel.TBPBaseModel

Parameters:

molarMass - molar mass in g/mol

density - specific gravity (g/cm³)

Returns:

boiling point in Kelvin

calcTC

public double calcTC(double molarMass,
 double density)

Calculate critical temperature using Lee-Kesler correlation with API correction.

Parameters:

molarMass - molar mass in g/mol

density - specific gravity (g/cm³)

Returns:

critical temperature in Kelvin

calcPC

public double calcPC(double molarMass,
 double density)

Calculate critical pressure using Lee-Kesler correlation with API correction.

Parameters:

molarMass - molar mass in g/mol

density - specific gravity (g/cm³)

Returns:

critical pressure in bar

calcAcentricFactor

public double calcAcentricFactor(double molarMass,
 double density)

Calculate acentric factor using Edmister correlation.

Specified by:

calcAcentricFactor in interface TBPModelInterface

Overrides:

calcAcentricFactor in class TBPfractionModel.TBPBaseModel

Parameters:

molarMass - molar mass in g/mol

density - specific gravity (g/cm³)

Returns:

acentric factor (dimensionless)

calcRacketZ

public double calcRacketZ(SystemInterface thermoSystem,
 double molarMass,
 double density)

calcRacketZ.

Specified by:

calcRacketZ in interface TBPModelInterface

Overrides:

calcRacketZ in class TBPfractionModel.TBPBaseModel

Parameters:

thermoSystem - a SystemInterface object

molarMass - a double

density - a double

Returns:

a double