Phase Package

Documentation for phase modeling in NeqSim.

Overview
Phase Types
Phase Interface
Gas Phase
Liquid Phase
Aqueous Phase
Solid Phases

Overview

Location: neqsim.thermo.phase

The phase package contains 62+ classes for modeling different phase types. Each phase type inherits from a base class that implements the PhaseInterface.

Phase Types

Available Phase Classes

Category	Classes
Gas	`PhaseGas`, `PhaseGasEos`, `PhaseGasCPA`, `PhaseGasPCSAFT`
Liquid	`PhaseLiquid`, `PhaseLiquidEos`, `PhaseLiquidCPA`, `PhaseLiquidPCSAFT`
Aqueous	`PhaseAqueous`, `PhaseAqueousEos`
Solid	`PhaseSolid`, `PhaseSolidComplex`, `PhaseHydrate`, `PhaseWax`

Phase Hierarchy

PhaseInterface
└── Phase (abstract base)
    ├── PhaseEos (EoS phases)
    │   ├── PhaseGasEos
    │   ├── PhaseLiquidEos
    │   └── ...
    ├── PhaseCPA (CPA phases)
    │   ├── PhaseGasCPA
    │   ├── PhaseLiquidCPA
    │   └── ...
    └── PhaseSolid
        ├── PhaseHydrate
        └── PhaseWax

Phase Interface

Common Methods

PhaseInterface phase = fluid.getPhase(0);

// Phase fraction
double beta = phase.getBeta();  // Mole fraction of total
double betaV = phase.getBetaV(); // Volume fraction

// Thermodynamic properties
double T = phase.getTemperature();
double P = phase.getPressure();
double V = phase.getMolarVolume();
double rho = phase.getDensity("kg/m3");
double Z = phase.getZ();

// Energetic properties
double H = phase.getEnthalpy("kJ/kg");
double S = phase.getEntropy("kJ/kgK");
double G = phase.getGibbsEnergy();
double U = phase.getInternalEnergy();
double A = phase.getHelmholtzEnergy();

// Heat capacities
double Cp = phase.getCp("J/molK");
double Cv = phase.getCv("J/molK");

// Transport properties
double visc = phase.getViscosity("cP");
double k = phase.getThermalConductivity("W/mK");
double D = phase.getDiffusionCoefficient("m2/s");

// Speed of sound
double u = phase.getSoundSpeed("m/s");

Component Access

// Get component in phase
ComponentInterface comp = phase.getComponent("methane");

// Mole fraction in phase
double x = comp.getx();

// Fugacity
double f = comp.getFugacity();
double phi = comp.getFugacityCoefficient();

Gas Phase

Properties

PhaseInterface gas = fluid.getGasPhase();

// Compressibility
double Z = gas.getZ();

// Density
double rhoGas = gas.getDensity("kg/m3");

// Viscosity
double muGas = gas.getViscosity("cP");

// Specific volume
double Vm = gas.getMolarVolume();

Gas Phase Types

// Standard EoS gas phase
PhaseGasEos gasEos = (PhaseGasEos) fluid.getGasPhase();

// CPA gas phase (for associating components)
PhaseGasCPA gasCPA = (PhaseGasCPA) fluid.getGasPhase();

// PC-SAFT gas phase
PhaseGasPCSAFT gasSAFT = (PhaseGasPCSAFT) fluid.getGasPhase();

Liquid Phase

Oil Phase

PhaseInterface oil = fluid.getLiquidPhase();

// Liquid density
double rhoLiq = oil.getDensity("kg/m3");

// API gravity
double API = 141.5 / (oil.getDensity("g/cm3") / 0.999) - 131.5;

// Viscosity
double muOil = oil.getViscosity("cP");

Multiple Liquid Phases

// When system has multiple liquid phases
if (fluid.getNumberOfLiquidPhases() > 1) {
    PhaseInterface oil = fluid.getPhase("oil");
    PhaseInterface aqueous = fluid.getPhase("aqueous");
}

Aqueous Phase

For water-rich liquid phases.

PhaseInterface aqueous = fluid.getPhase("aqueous");

// Water activity
double aW = aqueous.getComponent("water").getActivity();

// pH (if electrolytes present)
double pH = aqueous.getpH();

// Ionic strength
double I = aqueous.getIonicStrength();

Solid Phases

General Solid

// Enable solid phase check
fluid.setSolidPhaseCheck(true);

// Get solid phase if formed
if (fluid.hasSolidPhase()) {
    PhaseInterface solid = fluid.getSolidPhase();
    double solidFraction = solid.getBeta();
}

Hydrate Phase

// Hydrate formation check
fluid.setHydrateCheck(true);

ThermodynamicOperations ops = new ThermodynamicOperations(fluid);
ops.TPflash();

if (fluid.hasHydrate()) {
    PhaseInterface hydrate = fluid.getPhase("hydrate");
    double hydrateTemp = fluid.getHydrateTemperature();
}

Wax Phase

// Wax formation check
fluid.setWaxCheck(true);

ThermodynamicOperations ops = new ThermodynamicOperations(fluid);
ops.TPflash();

if (fluid.hasWax()) {
    PhaseInterface wax = fluid.getPhase("wax");
    double waxFraction = wax.getBeta();
}

Asphaltene Phases

NeqSim supports two approaches for modeling asphaltene precipitation:

Solid Asphaltene (PhaseType.ASPHALTENE): Traditional approach where precipitated asphaltene is treated as a solid phase with literature-based physical properties.
Liquid Asphaltene (PhaseType.LIQUID_ASPHALTENE): Pedersen’s approach where asphaltene is modeled as a liquid phase using cubic EOS (SRK/PR), enabling liquid-liquid equilibrium calculations.

Solid Asphaltene Approach

// Enable solid phase check for asphaltene
fluid.setSolidPhaseCheck("asphaltene");

ThermodynamicOperations ops = new ThermodynamicOperations(fluid);
ops.TPflash();

// Check for asphaltene phase using PhaseType
if (fluid.hasPhaseType(PhaseType.ASPHALTENE)) {
    PhaseInterface asphaltene = fluid.getPhaseOfType("asphaltene");
    double asphalteneFraction = asphaltene.getBeta();
    double density = asphaltene.getDensity("kg/m3");  // ~1150 kg/m³
    double viscosity = asphaltene.getViscosity("Pa*s"); // ~10,000 Pa·s
}

Pedersen’s Liquid Asphaltene Approach

Pedersen’s method treats asphaltene as a heavy liquid component using cubic EOS with estimated critical properties. This allows liquid-liquid equilibrium (LLE) calculations.

import neqsim.thermo.characterization.PedersenAsphalteneCharacterization;

// Create fluid system
SystemInterface fluid = new SystemSrkEos(373.15, 50.0);
fluid.addComponent("methane", 0.30);
fluid.addComponent("n-pentane", 0.25);  // Precipitant
fluid.addComponent("n-heptane", 0.20);
fluid.addComponent("nC10", 0.15);

// Create and configure asphaltene characterization
PedersenAsphalteneCharacterization asphChar = new PedersenAsphalteneCharacterization();
asphChar.setAsphalteneMW(750.0);     // g/mol
asphChar.setAsphalteneDensity(1.10); // g/cm³

// Add asphaltene as pseudo-component (before mixing rule)
asphChar.addAsphalteneToSystem(fluid, 0.10);  // 10 mol%
fluid.setMixingRule("classic");

// Perform TPflash with automatic asphaltene detection
boolean hasAsphaltene = PedersenAsphalteneCharacterization.TPflash(fluid);

// Check for asphaltene-rich liquid phase
if (fluid.hasPhaseType(PhaseType.LIQUID_ASPHALTENE)) {
    PhaseInterface asphLiquid = fluid.getPhaseOfType("asphaltene liquid");
    System.out.println("Asphaltene liquid fraction: " + asphLiquid.getBeta());
}

Detecting Asphaltene-Rich Phases

// Check if any phase is asphaltene-rich (works for both approaches)
for (int i = 0; i < fluid.getNumberOfPhases(); i++) {
    PhaseInterface phase = fluid.getPhase(i);
    if (phase.isAsphalteneRich()) {
        System.out.println("Phase " + i + " is asphaltene-rich");
    }
}

// Using StateOfMatter helper
import neqsim.thermo.phase.StateOfMatter;
boolean isAsph = StateOfMatter.isAsphaltene(phase.getType());

Asphaltene Phase Properties:

Property	Solid Approach	Liquid (Pedersen)	Unit
Density	~1150 (literature)	EOS-calculated	kg/m³
Heat Capacity (Cp)	~0.9 (literature)	EOS-calculated	kJ/kgK
Thermal Conductivity	~0.20 (literature)	EOS-calculated	W/mK
Viscosity	~10,000 (literature)	EOS-calculated	Pa·s
Speed of Sound	~1745 (literature)	EOS-calculated	m/s

Phase Identification

Phase Type Detection

// Get phase type
String type = phase.getPhaseTypeName();  // "gas", "oil", "aqueous", "asphaltene", etc.

// Check phase type using enum
boolean isGas = phase.getType() == PhaseType.GAS;
boolean isLiquid = phase.getType() == PhaseType.LIQUID;
boolean isAqueous = phase.getType() == PhaseType.AQUEOUS;
boolean isAsphaltene = phase.getType() == PhaseType.ASPHALTENE;
boolean isSolid = phase.getType() == PhaseType.SOLID;

// Check using string-based lookup (convenient API)
boolean hasGas = fluid.hasPhaseType("gas");
boolean hasAsphaltene = fluid.hasPhaseType("asphaltene");

Available PhaseType Values

PhaseType	Description	Value	StateOfMatter
`GAS`	Gas phase	1	GAS
`LIQUID`	Generic liquid	0	LIQUID
`OIL`	Oil/hydrocarbon liquid	2	LIQUID
`AQUEOUS`	Water-rich liquid	3	LIQUID
`HYDRATE`	Gas hydrate solid	4	SOLID
`WAX`	Wax solid	5	SOLID
`SOLID`	Generic solid	6	SOLID
`SOLIDCOMPLEX`	Complex solid	7	SOLID
`ASPHALTENE`	Asphaltene solid	8	SOLID
`LIQUID_ASPHALTENE`	Asphaltene liquid (Pedersen)	9	LIQUID

Stability Analysis

// Phase stability check
ThermodynamicOperations ops = new ThermodynamicOperations(fluid);
ops.checkStability();

boolean stable = fluid.isPhaseStable();

Phase Properties Calculation

EoS Properties

// Fugacity coefficients
for (int i = 0; i < phase.getNumberOfComponents(); i++) {
    double phi = phase.getComponent(i).getFugacityCoefficient();
    double lnPhi = phase.getComponent(i).getLogFugacityCoefficient();
}

// Compressibility factor derivatives
double dZdT = phase.getdZdT();
double dZdP = phase.getdZdP();

// Fugacity coefficient derivatives
double dPhidT = phase.getComponent(0).getdfugdT();
double dPhidP = phase.getComponent(0).getdfugdP();

Mixing Properties

// Excess properties
double GE = phase.getExcessGibbsEnergy();
double HE = phase.getExcessEnthalpy();
double SE = phase.getExcessEntropy();
double VE = phase.getExcessVolume();

// Activity coefficients (for liquid)
double gamma = phase.getComponent("ethanol").getActivityCoefficient();

Example: Phase Analysis

import neqsim.thermo.system.SystemSrkEos;
import neqsim.thermodynamicoperations.ThermodynamicOperations;

SystemSrkEos fluid = new SystemSrkEos(300.0, 50.0);
fluid.addComponent("methane", 0.80);
fluid.addComponent("ethane", 0.10);
fluid.addComponent("propane", 0.05);
fluid.addComponent("n-pentane", 0.05);
fluid.setMixingRule("classic");

ThermodynamicOperations ops = new ThermodynamicOperations(fluid);
ops.TPflash();

System.out.println("Number of phases: " + fluid.getNumberOfPhases());

for (int p = 0; p < fluid.getNumberOfPhases(); p++) {
    PhaseInterface phase = fluid.getPhase(p);
    
    System.out.println("\nPhase " + (p + 1) + ": " + phase.getPhaseTypeName());
    System.out.println("  Mole fraction: " + phase.getBeta());
    System.out.println("  Density: " + phase.getDensity("kg/m3") + " kg/m³");
    System.out.println("  Z-factor: " + phase.getZ());
    System.out.println("  Viscosity: " + phase.getViscosity("cP") + " cP");
    
    System.out.println("  Composition:");
    for (int i = 0; i < phase.getNumberOfComponents(); i++) {
        String name = phase.getComponent(i).getName();
        double x = phase.getComponent(i).getx();
        System.out.printf("    %s: %.4f%n", name, x);
    }
}

System Package - Fluid systems
Component Package - Component properties
Thermo Package - Package overview

Phase Package

Comprehensive Java library for thermodynamic, physical property, and process simulation. NeqSim provides tools for PVT analysis, phase equilibria, transport properties, and full process simulation.

Phase Package

Table of Contents

Overview

Phase Types

Available Phase Classes

Phase Hierarchy

Phase Interface

Common Methods

Component Access

Gas Phase

Properties

Gas Phase Types

Liquid Phase

Oil Phase

Multiple Liquid Phases

Aqueous Phase

Solid Phases

General Solid

Hydrate Phase

Wax Phase

Asphaltene Phases

Solid Asphaltene Approach

Pedersen’s Liquid Asphaltene Approach

Detecting Asphaltene-Rich Phases

Phase Identification

Phase Type Detection

Available PhaseType Values

Stability Analysis

Phase Properties Calculation

EoS Properties

Mixing Properties

Example: Phase Analysis

Phase Package

Table of Contents

Overview

Phase Types

Available Phase Classes

Phase Hierarchy

Phase Interface

Common Methods

Component Access

Gas Phase

Properties

Gas Phase Types

Liquid Phase

Oil Phase

Multiple Liquid Phases

Aqueous Phase

Solid Phases

General Solid

Hydrate Phase

Wax Phase

Asphaltene Phases

Solid Asphaltene Approach

Pedersen’s Liquid Asphaltene Approach

Detecting Asphaltene-Rich Phases

Phase Identification

Phase Type Detection

Available PhaseType Values

Stability Analysis

Phase Properties Calculation

EoS Properties

Mixing Properties

Example: Phase Analysis

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