neqsim.thermo.characterization.TBPfractionModel

All Implemented Interfaces:: Serializable

public class TBPfractionModel extends Object implements Serializable

TBP (True Boiling Point) Fraction Model for petroleum characterization.

This class provides multiple correlation models for estimating critical properties (Tc, Pc, ω) of petroleum pseudo-components based on molecular weight and density. These properties are essential for equation of state calculations in process simulation.

Background and Theory

Petroleum fluids contain thousands of individual hydrocarbon components that cannot all be individually characterized. Instead, heavy fractions (typically C7+) are lumped into pseudo-components. TBP models estimate the critical properties needed for equation of state calculations from easily measured properties like molecular weight (MW) and specific gravity (SG).

Available Models

Available TBP Models and Their Applications
Model	Best For	Key Features	Reference
PedersenSRK	General SRK EOS	Default, automatic light/heavy switching at MW=1120	Pedersen et al. (1984)
PedersenPR	General PR EOS	Optimized for Peng-Robinson EOS	Pedersen et al. (1984)
Lee-Kesler	General purpose	Uses Watson K-factor, wide applicability	Kesler & Lee (1976)
RiaziDaubert	Light fractions (MW < 300)	Simple exponential form, falls back to Pedersen for heavy	Riazi & Daubert (1980)
Twu	Paraffinic fluids (Kw > 12)	n-alkane reference with perturbation corrections	Twu (1984)
Cavett	Refining industry	API gravity corrections, hybrid Lee-Kesler approach	Cavett (1962)
Standing	Reservoir engineering	Simple power-law, quick estimates	Standing (1977)

Key Correlations

Critical Temperature

Pedersen: T_c = a₀·ρ + a₁·ln(M) + a₂·M + a₃/M

Lee-Kesler: T_c = 189.8 + 450.6·SG + (0.4244 + 0.1174·SG)·T_b + (0.1441 - 1.0069·SG)·10⁵/T_b

Riazi-Daubert: T_c = (5/9)·554.4·exp(-1.3478×10^-4·M - 0.61641·SG)·M^0.2998·SG^1.0555

Critical Pressure

Pedersen: P_c = exp(b₀ + b₁·ρ^b₄ + b₂/M + b₃/M²)

Lee-Kesler: ln(P_c) = 3.3864 - 0.0566/SG - f(T_b, SG)

Acentric Factor

Edmister: ω = (3/7)·log₁₀(P_c/P_ref)/(T_c/T_b - 1) - 1

Kesler-Lee (T_br < 0.8): ω = (ln(P_br) - 5.92714 + 6.09649/T_br + ...)/(15.2518 - ...)

Watson Characterization Factor

K_w = (1.8·T_b)^1/3/SG

Used to characterize fluid type:

K_w > 12.5: Paraffinic (gas condensates)
K_w 11.5-12.5: Mixed/intermediate
K_w 10.5-11.5: Naphthenic
K_w < 10.5: Aromatic

Model Selection Guidelines

Default choice: PedersenSRK (for SRK EOS) or PedersenPR (for PR EOS)
Gas condensates: Twu model (K_w > 12)
Heavy oils (MW > 500): PedersenSRKHeavyOil or PedersenPRHeavyOil
Light fractions (MW < 300): RiaziDaubert or Lee-Kesler
Reservoir engineering: Standing (simple, widely used)
Refining applications: Cavett (API gravity-based)

Usage Example


// Create a fluid with SRK equation of state
SystemInterface fluid = new SystemSrkEos(298.15, 50.0);

// Set the TBP model (optional, defaults to PedersenSRK for SRK EOS)
fluid.getCharacterization().setTBPModel("PedersenSRK");

// Add a TBP fraction: name, moles, MW (kg/mol), density (g/cm³)
fluid.addTBPfraction("C7", 1.0, 0.092, 0.73); // C7 fraction
fluid.addTBPfraction("C10", 0.5, 0.142, 0.78); // C10 fraction

// The model automatically calculates Tc, Pc, ω for each fraction
System.out.println("C7 Tc = " + fluid.getComponent("C7_PC").getTC() + " K");
System.out.println("C7 Pc = " + fluid.getComponent("C7_PC").getPC() + " bar");

// Get model recommendation based on fluid properties
TBPfractionModel model = new TBPfractionModel();
String recommended = model.recommendTBPModel(0.200, 0.85, "SRK");

Typical Property Ranges

Typical Property Ranges for Petroleum Fractions
Component	MW (g/mol)	SG	T_c (K)	P_c (bar)	ω
C7	96-100	0.72-0.74	540-560	27-30	0.30-0.35
C10	134-142	0.76-0.79	600-640	20-25	0.45-0.55
C20	275-285	0.85-0.87	750-800	12-15	0.85-0.95

References

Pedersen, K.S., Thomassen, P., Fredenslund, A. (1984). "Thermodynamics of Petroleum Mixtures Containing Heavy Hydrocarbons." Ind. Eng. Chem. Process Des. Dev., 23, 566-573.
Kesler, M.G., Lee, B.I. (1976). "Improve Prediction of Enthalpy of Fractions." Hydrocarbon Processing, 55(3), 153-158.
Riazi, M.R., Daubert, T.E. (1980). "Simplify Property Predictions." Hydrocarbon Processing, 59(3), 115-116.
Twu, C.H. (1984). "An Internally Consistent Correlation for Predicting the Critical Properties..." Fluid Phase Equilibria, 16, 137-150.
Cavett, R.H. (1962). "Physical Data for Distillation Calculations." Proc. 27th API Meeting, San Francisco.
Standing, M.B. (1977). "Volumetric and Phase Behavior of Oil Field Hydrocarbon Systems." SPE, Dallas.

Version:

$Id: $Id

Author:

ESOL

See Also:

Nested Class Summary

Nested Classes

Modifier and Type

Class

Description

class

TBPfractionModel.CavettModel

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

class

TBPfractionModel.LeeKesler

Lee-Kesler property estimation method.

class

TBPfractionModel.PedersenTBPModelPR

class

TBPfractionModel.PedersenTBPModelPR2

class

TBPfractionModel.PedersenTBPModelPRHeavyOil

class

TBPfractionModel.PedersenTBPModelSRK

Pedersen TBP Model for SRK equation of state.

class

TBPfractionModel.PedersenTBPModelSRKHeavyOil

class

TBPfractionModel.RiaziDaubert

Riazi-Daubert (1980) property estimation method.

class

TBPfractionModel.StandingModel

Standing (1977) property estimation method.

class

TBPfractionModel.TBPBaseModel

Abstract base class for TBP property estimation models.

class

TBPfractionModel.TwuModel

Twu (1984) property estimation method.
Field Summary

Fields

Modifier and Type

Field

Description

(package private) static org.apache.logging.log4j.Logger

logger

Logger object for class.

(package private) String

name

private static final long

serialVersionUID

Serialization version UID.
Constructor Summary

Constructors

Constructor

Description

TBPfractionModel()

Constructor for TBPfractionModel.
Method Summary

Modifier and Type

Method

Description

static double

calcAPIGravity(double specificGravity)

Calculate API gravity from specific gravity.

static double

calcSpecificGravity(double apiGravity)

Calculate specific gravity from API gravity.

double

calcWatsonKFactor(double molarMass, double density)

Calculate Watson characterization factor (Kw) from molecular weight and density.

static String[]

getAvailableModels()

Get list of all available TBP model names.

TBPModelInterface

getModel(String name)

Get a TBP model instance by name.

String

recommendTBPModel(double avgMW, double avgDensity, String eosType)

Recommend the most appropriate TBP model based on fluid properties and EOS type.

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
- logger
  
  static org.apache.logging.log4j.Logger logger
  
  Logger object for class.
- name
  
  String name
Constructor Details
- TBPfractionModel
  
  public TBPfractionModel()
  
  Constructor for TBPfractionModel.
Method Details
- calcAPIGravity
  
  public static double calcAPIGravity(double specificGravity)
  
  Calculate API gravity from specific gravity.
  API gravity is a measure of how heavy or light a petroleum liquid is compared to water. API gravity greater than 10 means the liquid is lighter than water and will float.
  
  Parameters:
  
  specificGravity - specific gravity relative to water (g/cm³)
  
  Returns:
  
  API gravity in degrees
- calcSpecificGravity
  
  public static double calcSpecificGravity(double apiGravity)
  
  Calculate specific gravity from API gravity.
  
  Parameters:
  
  apiGravity - API gravity in degrees
  
  Returns:
  
  specific gravity relative to water (g/cm³)
- calcWatsonKFactor
  public double calcWatsonKFactor(double molarMass, double density)
  
  Calculate Watson characterization factor (Kw) from molecular weight and density.
  The Watson K-factor is used to characterize petroleum fractions:
  
  Kw > 12.5: Paraffinic (gas condensates)
  
  Kw 11.5-12.5: Mixed/intermediate
  
  Kw 10.5-11.5: Naphthenic
  
  Kw < 10.5: Aromatic
  
  Parameters:
  
  molarMass - molar mass in kg/mol
  
  density - density in g/cm³ (specific gravity)
  
  Returns:
  
  Watson characterization factor (dimensionless)
- recommendTBPModel
  public String recommendTBPModel(double avgMW, double avgDensity, String eosType)
  
  Recommend the most appropriate TBP model based on fluid properties and EOS type.
  This method analyzes the plus fraction properties (molecular weight, density, Watson K-factor) and recommends the most suitable TBP correlation model. The recommendation considers:
  
  Fluid type (paraffinic, naphthenic, aromatic)
  
  Molecular weight range (light vs heavy)
  
  Equation of state being used (SRK vs PR)
  
  Parameters:
  
  avgMW - average molecular weight of plus fraction in kg/mol
  
  avgDensity - average density/specific gravity in g/cm³
  
  eosType - equation of state type: "SRK" or "PR"
  
  Returns:
  
  recommended model name as a String
- getAvailableModels
  
  public static String[] getAvailableModels()
  
  Get list of all available TBP model names.
  
  Returns:
  
  array of available model names
- getModel
  public TBPModelInterface getModel(String name)
  
  Get a TBP model instance by name.
  Available models and their recommended use cases:
  
  PedersenSRK: General purpose for SRK EOS, default choice
  
  PedersenSRKHeavyOil: SRK EOS for heavy oils (MW > 500 g/mol)
  
  PedersenPR: General purpose for PR EOS
  
  PedersenPR2: PR EOS with Søreide boiling point correlation
  
  PedersenPRHeavyOil: PR EOS for heavy oils
  
  RiaziDaubert: Light to medium petroleum fractions (MW < 300 g/mol)
  
  Lee-Kesler: General purpose, uses Watson K-factor
  
  Twu: Paraffinic fluids, based on n-alkane reference
  
  Cavett: Refining industry, API gravity based
  
  Standing: Simple power-law, reservoir engineering
  
  Parameters:
  
  name - model name (case-sensitive)
  
  Returns:
  
  TBPModelInterface instance, defaults to PedersenSRK if name not recognized

Class TBPfractionModel

Background and Theory

Available Models

Key Correlations

Critical Temperature

Critical Pressure

Acentric Factor

Watson Characterization Factor

Model Selection Guidelines

Usage Example

Typical Property Ranges

References

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class Object

Field Details

serialVersionUID

logger

name

Constructor Details

TBPfractionModel

Method Details

calcAPIGravity

calcSpecificGravity

calcWatsonKFactor

recommendTBPModel

getAvailableModels

getModel