Pure Component Parameters Database (COMP)

This guide provides detailed documentation of the COMP database, which stores pure component parameters used by NeqSim’s thermodynamic models. Understanding these parameters is essential for model selection, debugging, and extending NeqSim with new components.

Database Overview
Database Location and Format
Parameter Categories
Parameter Reference Table
Link to Thermodynamic Models
Component Types
Accessing Parameters in Code
Adding Custom Components
Related Database Tables

Database Overview

The COMP table is the primary pure component property database in NeqSim. It contains over 150 parameters per component, organized into functional groups that support different thermodynamic models and property calculations.

Key characteristics:

~260 components in the standard database
CSV format for easy maintenance and version control
Loaded at runtime into an in-memory H2 database
Extensible via temporary tables or database modification

Database Location and Format

Item	Value
File Path	`src/main/resources/data/COMP.csv`
Runtime Path	`data/COMP.csv` (in JAR)
Format	CSV with header row
Encoding	UTF-8
Primary Key	ID (integer)
Lookup Key	NAME (string, case-sensitive)

Parameter Categories

Basic Properties

Column	Description	Unit	Model Usage
`ID`	Unique component identifier	-	Internal indexing
`NAME`	Component name for lookup	-	`addComponent("methane", ...)`
`CASnumber`	CAS Registry Number	-	Component identification
`COMPTYPE`	Component type classification	-	Model selection (see Component Types)
`COMPINDEX`	Component index in database	-	Internal ordering
`FORMULA`	Chemical formula	-	Element calculations
`MOLARMASS`	Molar mass	g/mol	All models (stored internally as kg/mol)

Critical Properties

These parameters are fundamental to all cubic equations of state (SRK, PR, etc.).

Column	Description	Unit	Model Usage
`TC`	Critical temperature	°C	Converted to K internally: $T_c = T_{C,db} + 273.15$
`PC`	Critical pressure	bara	SRK, PR, CPA EoS parameter a and b
`ACSFACT`	Acentric factor (ω)	-	Alpha function: $m = f(\omega)$
`CRITVOL`	Critical molar volume	cm³/mol	Critical compressibility: $Z_c = \frac{P_c V_c}{R T_c}$
`NORMBOIL`	Normal boiling point	°C	Stored as K internally

Model linkage:

SRK EoS: $a = 0.42748 \frac{R^2 T_c^2}{P_c}$, $b = 0.08664 \frac{R T_c}{P_c}$
PR EoS: $a = 0.45724 \frac{R^2 T_c^2}{P_c}$, $b = 0.07780 \frac{R T_c}{P_c}$
Alpha function: $\alpha(T) = [1 + m(1-\sqrt{T_r})]^2$ where $m = f(\omega)$

Vapor Pressure Parameters

Parameters for Antoine-type vapor pressure correlations.

Column	Description	Unit	Model Usage
`AntoineVapPresLiqType`	Equation type	-	`pow10`, `log`, `exp`, `loglog`
`ANTOINEA`	Antoine A coefficient	-	Vapor pressure calculation
`ANTOINEB`	Antoine B coefficient	-	Vapor pressure calculation
`ANTOINEC`	Antoine C coefficient	-	Vapor pressure calculation
`ANTOINED`	Antoine D coefficient	-	Extended Antoine
`ANTOINEE`	Antoine E coefficient	-	Extended Antoine
`ANTOINESolidA`	Solid vapor pressure A	-	Sublimation pressure
`ANTOINESolidB`	Solid vapor pressure B	-	Sublimation pressure
`ANTOINESolidC`	Solid vapor pressure C	-	Sublimation pressure

Antoine equation forms:

pow10: $\log_{10}(P_{sat}) = A - \frac{B}{T + C}$ (P in mmHg, T in °C)
log: $\ln(P_{sat}) = A + \frac{B}{T} + C \ln(T) + D T^E$
exp: $P_{sat} = \exp(A - \frac{B}{T + C})$

Ideal Gas Heat Capacity

Polynomial coefficients for ideal gas heat capacity: $C_p^{ig} = A + BT + CT^2 + DT^3 + ET^4$

Column	Description	Unit
`CPA`	Coefficient A	J/(mol·K)
`CPB`	Coefficient B	J/(mol·K²)
`CPC`	Coefficient C	J/(mol·K³)
`CPD`	Coefficient D	J/(mol·K⁴)
`CPE`	Coefficient E	J/(mol·K⁵)
`CPsolid1-5`	Solid phase Cp coefficients	J/(mol·K)
`CPliquid1-5`	Liquid phase Cp coefficients	J/(mol·K)

Usage: Enthalpy, entropy, and Gibbs energy departure functions for all EoS models.

Liquid Phase Properties

Column	Description	Unit	Model Usage
`LIQDENS`	Liquid density at standard conditions	g/cm³	Density correlations
`RACKETZ`	Rackett compressibility factor	-	Rackett liquid density: $V = V_c Z_{RA}^{[1+(1-T_r)^{2/7}]}$
`racketZCPA`	Rackett Z for CPA model	-	CPA volume correction
`volcorrSRK_T`	SRK volume translation	-	Péneloux correction: $V_{corr} = V_{EoS} - c$
`volcorrCPA_T`	CPA volume translation	-	CPA Péneloux correction
`STDDENS`	Standard density	g/cm³	Reference conditions
`LIQUIDDENSITYCOEFS1-5`	Liquid density correlation coefficients	-	Temperature-dependent density

Transport Properties

Column	Description	Unit	Model Usage
`DIPOLEMOMENT`	Dipole moment	Debye	Polar corrections
`VISCFACT`	Viscosity correction factor	-	Corresponding states
`LIQVISCMODEL`	Liquid viscosity model type	-	Model selection (1-4)
`LIQVISC1-4`	Liquid viscosity parameters	-	Andrade equation: $\ln(\eta) = A + B/T + C\ln(T) + DT$
`LIQUIDCONDUCTIVITY1-3`	Liquid thermal conductivity	-	$k = A + BT + CT^2$
`PARACHOR`	Parachor	-	Surface tension: $\sigma^{1/4} = P[\rho_L - \rho_V]$
`PARACHOR_CPA`	Parachor for CPA model	-	CPA surface tension
`criticalViscosity`	Critical viscosity	Pa·s	Transport correlations

Equation of State Parameters

Attractive Term Parameters

Column	Description	Unit	Model Usage
`PVMODEL`	PV model type	-	`Classic` for standard EoS
`MC1`, `MC2`, `MC3`	Mathias-Copeman parameters (SRK)	-	Enhanced alpha function
`MCPR1`, `MCPR2`, `MCPR3`	Mathias-Copeman parameters (PR)	-	PR alpha function
`TwuCoon1-3`	Twu-Coon alpha function parameters	-	Twu-Coon attractive term
`SCHWARTZENTRUBER1-3`	Schwartzentruber parameters	-	Schwartzentruber EoS
`MC1Solid-MC3Solid`	Solid phase Mathias-Copeman	-	Solid fugacity

Mathias-Copeman alpha function: $\alpha = [1 + c_1(1-\sqrt{T_r}) + c_2(1-\sqrt{T_r})^2 + c_3(1-\sqrt{T_r})^3]^2$

Lennard-Jones Parameters

Column	Description	Unit	Model Usage
`LJDIAMETER`	LJ molecular diameter	Å	Gas viscosity, diffusion
`LJEPS`	LJ energy parameter	K	ε/k_B
`SphericalCoreRadius`	Hard-core radius	-	LJ potential
`LJDIAMETERHYDRATE`	LJ diameter for hydrates	Å	Hydrate equilibrium
`LJEPSHYDRATE`	LJ energy for hydrates	K	Hydrate cage interaction

Association Parameters (CPA/SAFT)

Parameters for Cubic-Plus-Association (CPA) and PC-SAFT models.

Column	Description	Unit	Model Usage
`associationsites`	Number of association sites	-	0, 1, 2, 3, or 4
`associationscheme`	Association scheme	-	`0`, `1A`, `2A`, `2B`, `3B`, `4C`
`associationenergy`	Association energy (ε^AB)	J/mol	CPA association term
`associationboundingvolume_SRK`	Association volume (β) for SRK-CPA	-	SRK-CPA
`associationboundingvolume_PR`	Association volume (β) for PR-CPA	-	PR-CPA
`aCPA_SRK`	CPA a parameter (SRK base)	Pa·m⁶/mol²	SRK-CPA
`bCPA_SRK`	CPA b parameter (SRK base)	m³/mol	SRK-CPA
`mCPA_SRK`	CPA m parameter (SRK base)	-	SRK-CPA
`aCPA_PR`	CPA a parameter (PR base)	Pa·m⁶/mol²	PR-CPA
`bCPA_PR`	CPA b parameter (PR base)	m³/mol	PR-CPA
`mCPA_PR`	CPA m parameter (PR base)	-	PR-CPA

PC-SAFT Parameters

Column	Description	Unit	Model Usage
`mSAFT`	Number of segments	-	Chain length
`sigmaSAFT`	Segment diameter	Å	Hard-sphere term
`epsikSAFT`	Segment energy	K	ε/k_B
`associationboundingvolume_PCSAFT`	Association volume	-	PC-SAFT association
`associationenergy_PCSAFT`	Association energy	K	PC-SAFT association

Association schemes: | Scheme | Sites | Example Molecules | |——–|——-|——————-| | 0 | 0 | Non-associating (hydrocarbons) | | 1A | 1 | HCl, aromatic compounds | | 2A | 2 | CO₂ (electron donor/acceptor) | | 2B | 2 | Alcohols (1 proton donor, 1 acceptor) | | 3B | 3 | Amines | | 4C | 4 | Water, glycols (2 donors, 2 acceptors) |

Hydrate Parameters

Parameters for gas hydrate equilibrium calculations.

Column	Description	Unit	Model Usage
`HydrateFormer`	Hydrate-forming capability	-	`yes` or `no`
`HydrateA1Small`, `HydrateB1Small`	Type I small cage (512)	-	Langmuir constants
`HydrateA1Large`, `HydrateB1Large`	Type I large cage (51262)	-	Langmuir constants
`HydrateA2Small`, `HydrateB2Small`	Type II small cage (512)	-	Langmuir constants
`HydrateA2Large`, `HydrateB2Large`	Type II large cage (51264)	-	Langmuir constants
`A1_smallGF-B2_largeGF`	Graffis parameters	-	Alternative parameterization
`SphericalCoreRadiusHYDRATE`	Core radius for hydrates	-	Cavity occupation

Thermodynamic Reference Data

Column	Description	Unit	Model Usage
`Href`	Reference enthalpy	J/mol	Enthalpy calculations
`GIBBSENERGYOFFORMATION`	Gibbs energy of formation	J/mol	Chemical equilibrium
`ENTHALPYOFFORMATION`	Standard enthalpy of formation	J/mol	Reaction thermodynamics
`ABSOLUTEENTROPY`	Absolute entropy	J/(mol·K)	Entropy calculations
`HEATOFFUSION`	Heat of fusion	J/mol	Solid-liquid equilibrium
`Hsub`	Heat of sublimation	J/mol	Solid-vapor equilibrium
`TRIPLEPOINTTEMPERATURE`	Triple point temperature	K	Phase boundaries
`TRIPLEPOINTPRESSURE`	Triple point pressure	bar	Phase boundaries
`TRIPLEPOINTDENSITY`	Triple point density	kg/m³	Reference state
`MELTINGPOINTTEMPERATURE`	Melting point	K	Solid calculations

Ionic and Electrolyte Parameters

Column	Description	Unit	Model Usage
`IONICCHARGE`	Ionic charge	-	Electrolyte models
`REFERENCESTATETYPE`	Reference state	-	`solvent` or `solute`
`DIELECTRICPARAMETER1-5`	Dielectric parameters	-	Electrolyte activity
`DeshMatIonicDiameter`	Debye-Hückel diameter	Å	Electrolyte models
`calcActivity`	Activity calculation flag	-	0 or 1

Henry’s Law Parameters

Column	Description	Unit
`HenryCoef1`	Henry constant A	-
`HenryCoef2`	Henry constant B	-
`HenryCoef3`	Henry constant C	-
`HenryCoef4`	Henry constant D	-

Henry’s law correlation: $\ln(H) = A + \frac{B}{T} + C\ln(T) + DT$

Solid Phase Parameters

Column	Description	Unit
`SOLIDDENSITYCOEFS1-5`	Solid density coefficients	-
`HEATOFVAPORIZATIONCOEFS1-5`	Heat of vaporization coefficients	-
`waxformer`	Wax-forming component	-

Parameter Reference Table

Complete parameter list with units and typical values:

Parameter	Unit	Example (methane)	Example (water)
`MOLARMASS`	g/mol	16.043	18.015
`TC`	°C	-82.59	374.15
`PC`	bara	45.99	220.89
`ACSFACT`	-	0.0115	0.344
`CRITVOL`	cm³/mol	99.0	56.0
`NORMBOIL`	°C	-161.55	100.0
`LIQDENS`	g/cm³	0.422	0.999
`RACKETZ`	-	0.0	0.0
`DIPOLEMOMENT`	Debye	0.0	1.8
`associationsites`	-	0	4
`HydrateFormer`	-	yes	no

Link to Thermodynamic Models

How Parameters Feed into Models

┌─────────────────────────────────────────────────────────────────┐
│                      COMP Database                              │
├─────────────────────────────────────────────────────────────────┤
│  TC, PC, ACSFACT  ──────────────> Cubic EoS (SRK, PR)          │
│  MC1, MC2, MC3    ──────────────> Mathias-Copeman α(T)         │
│  TwuCoon1-3       ──────────────> Twu-Coon α(T)                │
│  aCPA, bCPA, mCPA ──────────────> CPA EoS                      │
│  associationsites ──────────────> CPA/SAFT Association         │
│  mSAFT, σSAFT, εSAFT ──────────> PC-SAFT                       │
│  UNIFAC groups    ──────────────> Activity models              │
│  LJDIAMETER, LJEPS ─────────────> Transport properties         │
│  HydrateA/B params ─────────────> Hydrate equilibrium          │
│  CPA, CPB, CPC... ──────────────> Enthalpy/Entropy             │
│  ANTOINEA-E       ──────────────> Vapor pressure               │
└─────────────────────────────────────────────────────────────────┘

Model-Parameter Mapping

Model Class	Key Parameters
`SystemSrkEos`	TC, PC, ACSFACT, MC1-3, RACKETZ
`SystemPrEos`	TC, PC, ACSFACT, MCPR1-3
`SystemSrkCPA`	aCPA_SRK, bCPA_SRK, mCPA_SRK, associationsites, associationenergy, associationboundingvolume_SRK
`SystemPrCPA`	aCPA_PR, bCPA_PR, mCPA_PR, associationboundingvolume_PR
`SystemPCSAFT`	mSAFT, sigmaSAFT, epsikSAFT, associationboundingvolume_PCSAFT
`SystemGERG2008Eos`	Uses internal GERG parameters, but TC/PC for initialization
`SystemUNIFAC`	TC, PC (for vapor), UNIFAC groups from UNIFACcomp table

Component Types

The COMPTYPE field classifies components for model selection:

Type	Description	Examples
`HC`	Hydrocarbon	methane, ethane, propane, benzene
`inert`	Inert gas	nitrogen, CO2, oxygen, argon
`ion`	Ionic species	Na+, Cl-, HCO3-, Ca++
`amine`	Amine compounds	MDEA, MEA, DEA
`alcohol`	Alcohols	methanol, ethanol
`glycol`	Glycol compounds	MEG, DEG, TEG
`ice`	Ice/solid water	ice
`TBP`	TBP pseudo-component	Generated from characterization
`plus`	Plus fraction	C7+, C10+, etc.

Accessing Parameters in Code

Reading Component Properties

// Create a system and access component properties
SystemInterface fluid = new SystemSrkEos(298.15, 10.0);
fluid.addComponent("methane", 1.0);
fluid.init(0);

// Access pure component parameters
ComponentInterface comp = fluid.getPhase(0).getComponent("methane");
double Tc = comp.getTC();           // Critical temperature [K]
double Pc = comp.getPC();           // Critical pressure [bara]
double omega = comp.getAcentricFactor();  // Acentric factor [-]
double Mw = comp.getMolarMass();    // Molar mass [kg/mol]
double Tb = comp.getNormalBoilingPoint(); // Normal boiling point [K]

System.out.println("Methane Tc = " + Tc + " K");
System.out.println("Methane Pc = " + Pc + " bara");
System.out.println("Methane ω = " + omega);

Modifying Component Properties

// Modify properties for sensitivity analysis
comp.setTC(190.6);  // Set new Tc in Kelvin
comp.setPC(46.0);   // Set new Pc in bara
comp.setAcentricFactor(0.012);

// Re-initialize to apply changes
fluid.init(0);

Adding Custom Components

Method 1: Database Modification

Add a new row to COMP.csv with all required parameters.

Method 2: Runtime Addition

// Add a pseudo-component with custom properties
SystemInterface fluid = new SystemSrkEos(298.15, 50.0);

// Add TBP fraction with molar mass and density
fluid.addTBPfraction("C7_custom", 0.1, 95.0, 0.72);  // name, moles, MW, SG

// Or add component and modify properties
fluid.addComponent("n-heptane", 1.0);
ComponentInterface comp = fluid.getPhase(0).getComponent("n-heptane");
comp.setTC(540.0);
comp.setPC(27.4);
comp.setAcentricFactor(0.35);

// Initialize database for binary parameters
fluid.createDatabase(true);
fluid.setMixingRule(2);

Method 3: Temporary Tables

// Enable temporary tables for session-specific components
NeqSimDataBase.setCreateTemporaryTables(true);

// Components added to "comptemp" table
fluid.getPhase(0).getComponent(0).insertComponentIntoDatabase("comptemp");

// Remember to disable after use
NeqSimDataBase.setCreateTemporaryTables(false);

The COMP table works with several related tables:

Table	Purpose	Key Columns
`INTER`	Binary interaction parameters (kij)	comp1, comp2, kij, model
`UNIFACcomp`	UNIFAC group assignments	compname, group, count
`UNIFACGroupParam`	UNIFAC group parameters	groupid, R, Q
`UNIFACInterParam*`	UNIFAC group interaction parameters	group1, group2, aij
`MBWR32param`	MBWR equation parameters	comp, coefficients
`AdsorptionParameters`	Adsorption isotherm parameters	comp, adsorbent, params

References

Soave, G. (1972). Equilibrium constants from a modified Redlich-Kwong equation of state. Chemical Engineering Science, 27(6), 1197-1203.
Peng, D. Y., & Robinson, D. B. (1976). A new two-constant equation of state. Industrial & Engineering Chemistry Fundamentals, 15(1), 59-64.
Kontogeorgis, G. M., et al. (1999). An equation of state for associating fluids. Industrial & Engineering Chemistry Research, 38(10), 4073-4082.
Gross, J., & Sadowski, G. (2001). Perturbed-chain SAFT: An equation of state based on a perturbation theory for chain molecules. Industrial & Engineering Chemistry Research, 40(4), 1244-1260.

Pure Component Parameters Database (COMP)

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

Pure Component Parameters Database (COMP)

Table of Contents

Database Overview

Database Location and Format

Parameter Categories

Basic Properties

Critical Properties

Vapor Pressure Parameters

Ideal Gas Heat Capacity

Liquid Phase Properties

Transport Properties

Equation of State Parameters

Attractive Term Parameters

Lennard-Jones Parameters

Association Parameters (CPA/SAFT)

PC-SAFT Parameters

Hydrate Parameters

Thermodynamic Reference Data

Ionic and Electrolyte Parameters

Henry’s Law Parameters

Solid Phase Parameters

Parameter Reference Table

Link to Thermodynamic Models

How Parameters Feed into Models

Model-Parameter Mapping

Component Types

Accessing Parameters in Code

Reading Component Properties

Modifying Component Properties

Adding Custom Components

Method 1: Database Modification

Method 2: Runtime Addition

Method 3: Temporary Tables

See Also

References

Pure Component Parameters Database (COMP)

Table of Contents

Database Overview

Database Location and Format

Parameter Categories

Basic Properties

Critical Properties

Vapor Pressure Parameters

Ideal Gas Heat Capacity

Liquid Phase Properties

Transport Properties

Equation of State Parameters

Attractive Term Parameters

Lennard-Jones Parameters

Association Parameters (CPA/SAFT)

PC-SAFT Parameters

Hydrate Parameters

Thermodynamic Reference Data

Ionic and Electrolyte Parameters

Henry’s Law Parameters

Solid Phase Parameters

Parameter Reference Table

Link to Thermodynamic Models

How Parameters Feed into Models

Model-Parameter Mapping

Component Types

Accessing Parameters in Code

Reading Component Properties

Modifying Component Properties

Adding Custom Components

Method 1: Database Modification

Method 2: Runtime Addition

Method 3: Temporary Tables

Related Database Tables

See Also

References