This document provides a comprehensive list of all components available in NeqSim. Use a canonical database name or a recognized alias when adding or retrieving components; name matching is case-insensitive but never fuzzy.

Quick Reference

// Adding components by name
fluid.addComponent("methane", 0.85);      // Mole fraction
fluid.addComponent("CO2", 0.02);          // Case-insensitive
fluid.addComponent("water", 1.0);         // Keyword "water" is recommended

// Adding by molar flow
fluid.addComponent("ethane", 100.0, "mol/sec");

Standard vs Extended Component Database

NeqSim provides two pure component parameter databases:

Database Components Performance Use Case
Standard 389 Fast (embedded) Typical oil & gas simulations
Extended 76,704 Slower (loaded on demand) Specialty chemicals, research

The standard database is the default and covers most components needed for oil & gas applications. It loads instantly as an embedded database.

The extended database contains every component of the standard database with identical parameters, plus around 76,000 additional components. useExtendedComponentDatabase(true) replaces the COMP table rather than adding to it, so this superset relationship matters: any component present only in the standard file would disappear from fluids created after the switch. It is enforced by NeqSimDataBaseComponentLookupTest.extendedDatabaseContainsEveryStandardComponent.

Data provenance: the origin of the additional components in COMP_EXT.csv is not currently documented, and its entries have not been validated against a primary source such as DIPPR 801 or NIST. Treat parameters taken from the extended database as unverified, and check them before using them in engineering work.

Switching Between Databases

Java

import neqsim.util.database.NeqSimDataBase;
import neqsim.thermo.system.SystemSrkEos;

// Default: use standard database (fast)
NeqSimDataBase.useExtendedComponentDatabase(false);

// Switch to extended database (76,000+ components)
NeqSimDataBase.useExtendedComponentDatabase(true);

// Now you can use specialty components
SystemSrkEos fluid = new SystemSrkEos(298.15, 1.01325);
fluid.addComponent("furoin", 1.0);  // Only in extended database
fluid.setMixingRule("classic");

// Switch back to standard for performance
NeqSimDataBase.useExtendedComponentDatabase(false);

Python

from neqsim import jneqsim
from neqsim.thermo import fluid, TPflash, printFrame

# Check current database mode
print("Using extended database:", 
      jneqsim.util.database.NeqSimDataBase.useExtendedComponentDatabase())

# List components in standard database
jneqsim.util.database.NeqSimDataBase.useExtendedComponentDatabase(False)
standard_components = jneqsim.util.database.NeqSimDataBase.getComponentNames()
print(f"Standard database: {len(standard_components)} components")

# Switch to extended database
jneqsim.util.database.NeqSimDataBase.useExtendedComponentDatabase(True)
extended_components = jneqsim.util.database.NeqSimDataBase.getComponentNames()
print(f"Extended database: {len(extended_components)} components")

# Use a specialty component from extended database
fluid1 = fluid('srk')
fluid1.setTemperature(20.0, 'C')
fluid1.setPressure(1.1, 'bara')
fluid1.addComponent('furoin', 1.0)  # Available only in extended database
TPflash(fluid1)
fluid1.initProperties()
printFrame(fluid1)

# Switch back to standard for normal operations
jneqsim.util.database.NeqSimDataBase.useExtendedComponentDatabase(False)

Database Source Files

The database CSV files are located in the NeqSim repository:

The UMR-PRU table is joined to COMP.csv on an exact match of the name, so a component whose name differs between the two files silently ends up with no groups. 277 of the 389 standard components carry a group assignment; the rest are ions, salts and other species the model does not apply to.

COMP.csv also carries an InChIKey column, a structure-derived identifier that is the same for a substance however it is named. It is the reliable way to tell whether two rows are the same molecule, since a CAS number can be absent, wrong, or registered separately for each stereoisomer.

When to Use Extended Database

Scenario Database
Natural gas processing Standard
Oil refining Standard
Gas dehydration (TEG/MEG) Standard
Amine sweetening Standard
Specialty solvents Extended
Pharmaceutical research Extended
Academic/research chemicals Extended
Unknown component lookup Extended

Performance Note: The extended database loads components into an embedded database on demand, which takes slightly longer than the pre-loaded standard database. For production simulations with common components, use the standard database.

Pure-Component Vapor-Pressure Correlations

ComponentInterface.getAntoineVaporPressure(T) takes temperature in K and returns pressure in bar. Its coefficients can represent several correlations. Explicit pow10 and pow10KPa labels keep their existing interpretation. For other labels, |ANTOINEE| > 1e-12 selects the five-parameter DIPPR-101 form for available data, even when the database label is the legacy log or exp:

\[P_{\mathrm{sat}}[\mathrm{bar}] = \frac{\exp(A + B/T + C\ln T + DT^E)}{10^5}\]

The stored DIPPR coefficients give pressure in Pa before conversion to bar. getAntoineVaporPressuredT(T) uses the same selection and returns the analytical DIPPR derivative in bar/K. This keeps the derivative consistent with the pressure used by getAntoineVaporTemperature(P) and activity-coefficient models. Available rows with zero exponent retain their existing correlation selection.

The pow10KPa form also has an analytical derivative in bar/K: $dP_{\mathrm{sat}}/dT = P_{\mathrm{sat}}\ln(10)B/(T+C)^2$. It uses the existing pressure $P_{\mathrm{sat}} = 10^{A-B/(T+C)}/10^5$ in bar with T in K, including when a nonzero E is present. The legacy pow10KPa label does not change this scale to a kPa-to-bar conversion. ComponentPow10KPaVaporPressureTest verifies analytical values, finite-difference slopes, pressure/temperature round trips, and unavailable-data behavior with prescribed test coefficients; those coefficients are not physical fits.

For example, the stored coefficients at 298.15 K give 0.91801 bar for i-pentane, 9.53257 bar for propanePVTsim, and 2.43661 bar for nbutanePVTsim. ComponentAntoineVaporPressureTest checks these values, pressure/temperature round trips, finite-difference derivatives, and an independent NIST isopentane correlation.

hasAntoineVaporPressureCorrelation() reports missing data explicitly. The known shared placeholders, copied water coefficients on unrelated compounds, and all ions are marked none in the standard table. Pressure, derivative and inverse queries return Double.NaN for these rows; pressure and derivative also reject temperatures above Tc, and inversion rejects pressures above Pc. The extended database preserves these corrections and acetone’s corrected NIST coefficients. See the database guide for units, applicability, compatibility and acetone provenance.

Correct dispatch does not validate other coefficients or extend their fitted temperature range. The dispatch correction in #3768 and missing-data policy in #3771 address distinct defects.

Component Name Resolution

The same molecule is named differently by different tools. addComponent therefore passes the name through neqsim.thermo.component.ComponentNameResolver before looking it up, so all of the following reach the same component:

fluid.addComponent("224-TM-C5", 1.0);               // database shorthand
fluid.addComponent("2,2,4-trimethylpentane", 1.0);  // systematic name
fluid.addComponent("isooctane", 1.0);               // trivial name
fluid.addComponent("ISOOCTANE", 1.0);               // any letter case

Name resolution is symmetric across the name-taking fluid APIs. A recognized name accepted by addComponent can be reused with hasComponent, getComponent, phase-level getComponent, setComponentCriticalParameters, setBinaryInteractionParameter, and removeComponent:

ComponentInterface component = fluid.getComponent("2,2,4-trimethylpentane");
ComponentInterface phaseComponent =
    fluid.getPhase(0).getComponent("isooctane");

if (fluid.hasComponent("ISOOCTANE")) {
    // Both lookups return the component stored under the canonical name 224-TM-C5.
    String canonicalName = component.getComponentName();
}

Exact canonical names are checked first. Only after an exact lookup fails does getComponent consult the alias table. Unknown, ambiguous, and near-miss names are not guessed: getComponent("methan") returns null. Check user-supplied names with hasComponent before dereferencing the result. The executable ComponentAliasApiSymmetryTest protects the same lookup, mutation, and removal contract.

The resolver recognises:

Convention Example Resolves to
Database name, any case N-HEPTANE n-heptane
Reservoir shorthand C1, nC4, iC5, H2O methane, n-butane, i-pentane, water
Normal-chain prefix n-decane, n-pentylbenzene nC10, nC5-Benzene
Systematic name 2,2,4-trimethylpentane 224-TM-C5
Trivial name isopentane, neopentane, cyclohexane i-pentane, 22-dim-C3, c-hexane
Inverted CAS index name Cyclohexane, 1,2,4-trimethyl- 1.2.4-TMcyC6
Either locant separator 1,2,3-TM-Benzene or 1.2.3-TM-Benzene 1.2.3-TM-Benzene

Stereochemistry is never guessed. Where the database holds both partners of a cis/trans pair, the unqualified parent name is deliberately not resolved and is passed through unchanged:

ComponentNameResolver.resolve("cis-1,3-dimethylcyclohexane"); // "cis-13-DM-cy-C6"
ComponentNameResolver.resolve("1,3-dimethylcyclopentane");    // unchanged - cis and trans both exist

A name the resolver does not know is returned unchanged, so components that exist only in the extended database are unaffected. The optional n- prefix is accepted only for aliases whose database target is explicitly a normal-chain nC... component. It is not stripped generically: n-water, n-acetone, and n-isobutane therefore remain unknown and unchanged.

To inspect or extend the tables:

ComponentNameResolver.getSynonyms();        // normalised synonym -> database name
ComponentNameResolver.getCanonicalNames();  // normalised database name -> exact database name
ComponentNameResolver.isKnownName("isooctane");

Light Hydrocarbons (C1-C4)

Component Name Formula CAS Number MW (g/mol) Tc (K) Pc (bar) Notes
methane CH₄ 74-82-8 16.04 190.6 46.0 Primary natural gas component
ethane C₂H₆ 74-84-0 30.07 305.4 48.8  
propane C₃H₈ 74-98-6 44.10 369.8 42.5 LPG component
i-butane C₄H₁₀ 75-28-5 58.12 408.1 36.5 Isobutane
n-butane C₄H₁₀ 106-97-8 58.12 425.2 38.0  

Medium Hydrocarbons (C5-C10)

Component Name Formula CAS Number MW (g/mol) Tc (K) Pc (bar) Notes
i-pentane C₅H₁₂ 78-78-4 72.15 460.4 33.8 Isopentane
n-pentane C₅H₁₂ 109-66-0 72.15 469.7 33.7  
22-dim-C3 C₅H₁₂ 463-82-1 72.15 433.8 32.0 Neopentane
n-hexane C₆H₁₄ 110-54-3 86.18 507.4 30.1  
c-hexane C₆H₁₂ 110-82-7 84.16 553.5 40.7 Cyclohexane
benzene C₆H₆ 71-43-2 78.11 562.2 48.9 Aromatic
n-heptane C₇H₁₆ 142-82-5 100.20 540.2 27.4  
c-C7 C₇H₁₄ 291-64-5 98.19 604.3 38.4 Cycloheptane
toluene C₇H₈ 108-88-3 92.14 591.8 41.0 Methylbenzene
n-octane C₈H₁₈ 111-65-9 114.23 568.8 24.9  
c-C8 C₈H₁₆ 292-64-8 112.22 647.2 35.6 Cyclooctane
m-Xylene C₈H₁₀ 108-38-3 106.17 617.0 35.4  
ethylbenzene C₈H₁₀ 100-41-4 106.17 617.2 36.0  
n-nonane C₉H₂₀ 111-84-2 128.26 594.6 22.9  
n-decane C₁₀H₂₂ 124-18-5 142.28 617.7 21.2  

Heavy Hydrocarbons (C11+)

Component Name Formula CAS Number MW (g/mol) Tc (K) Pc (bar)
nC11 C₁₁H₂₄ 1120-21-4 156.31 638.8 19.7
nC12 C₁₂H₂₆ 112-40-3 170.34 658.2 18.2
nC13 C₁₃H₂₈ 629-50-5 184.37 676.0 17.2
nC14 C₁₄H₃₀ 629-59-4 198.39 692.4 16.2
nC15 C₁₅H₃₂ 629-62-9 212.42 707.0 15.2
nC16 C₁₆H₃₄ 544-76-3 226.45 720.6 14.4
nC17 C₁₇H₃₆ 629-78-7 240.47 733.4 13.7
nC18 C₁₈H₃₈ 593-45-3 254.50 745.3 13.0
nC19 C₁₉H₄₀ 629-92-5 268.53 756.4 12.4
nC20 C₂₀H₄₂ 112-95-8 282.55 767.0 11.8
nC21 C₂₁H₄₄ 629-94-7 296.58 778.0 11.4
nC22 C₂₂H₄₆ 629-97-0 310.61 787.0 10.9
nC23 C₂₃H₄₈ 638-67-5 324.63 796.0 10.5
nC24 C₂₄H₅₀ 646-31-1 338.66 804.0 10.1
nC25 C₂₅H₅₂ 629-99-2 352.69 812.0 9.8

Acid Gases and Inorganics

Component Name Formula CAS Number MW (g/mol) Notes
CO2 CO₂ 124-38-9 44.01 Carbon dioxide
H2S H₂S 7783-06-4 34.08 Hydrogen sulfide
nitrogen N₂ 7727-37-9 28.01  
N2 N₂ 7727-37-9 28.01 Alias for nitrogen
oxygen O₂ 7782-44-7 32.00  
argon Ar 7440-37-1 39.95  
helium He 7440-59-7 4.00  
hydrogen H₂ 1333-74-0 2.02  
H2 H₂ 1333-74-0 2.02 Alias for hydrogen
CO CO 630-08-0 28.01 Carbon monoxide
SO2 SO₂ 7446-09-5 64.07 Sulfur dioxide
NO NO 10102-43-9 30.01 Nitric oxide
NO2 NO₂ 10102-44-0 46.01 Nitrogen dioxide
COS COS 463-58-1 60.08 Carbonyl sulfide
H2O H₂O 7732-18-5 18.02 Water (use water preferred)
water H₂O 7732-18-5 18.02 Preferred name for water

Glycols (TEG/MEG Dehydration)

Component Name Formula CAS Number MW (g/mol) Notes
MEG C₂H₆O₂ 107-21-1 62.07 Monoethylene glycol (hydrate inhibitor)
TEG C₆H₁₄O₄ 112-27-6 150.17 Triethylene glycol (gas dehydration)
DEG C₄H₁₀O₃ 111-46-6 106.12 Diethylene glycol
PG C₃H₈O₂ 57-55-6 76.09 Propylene glycol

Amines (Gas Sweetening)

Component Name Formula CAS Number MW (g/mol) Notes
MDEA C₅H₁₃NO₂ 105-59-9 119.16 Methyldiethanolamine
DEA C₄H₁₁NO₂ 111-42-2 105.14 Diethanolamine
MEA C₂H₇NO 141-43-5 61.08 Monoethanolamine
Piperazine C₄H₁₀N₂ 110-85-0 86.14 Promoter for MDEA
ammonia NH₃ 7664-41-7 17.03  

Alcohols

Component Name Formula CAS Number MW (g/mol) Notes
methanol CH₃OH 67-56-1 32.04 Hydrate inhibitor
ethanol C₂H₅OH 64-17-5 46.07  
1-propanol C₃H₇OH 71-23-8 60.10 n-Propanol
2-propanol C₃H₇OH 67-63-0 60.10 Isopropanol
1-butanol C₄H₉OH 71-36-3 74.12 n-Butanol
2-butanol C₄H₉OH 78-92-2 74.12 sec-Butanol

Refrigerants

Component Name Formula CAS Number MW (g/mol) Notes
R-134a C₂H₂F₄ 811-97-2 102.03 1,1,1,2-Tetrafluoroethane
R-22 CHClF₂ 75-45-6 86.47 Chlorodifluoromethane
R-32 CH₂F₂ 75-10-5 52.02 Difluoromethane
R-125 C₂HF₅ 354-33-6 120.02 Pentafluoroethane
R-143a C₂H₃F₃ 420-46-2 84.04 1,1,1-Trifluoroethane
R-152a C₂H₄F₂ 75-37-6 66.05 1,1-Difluoroethane
R-1234yf C₃H₂F₄ 754-12-1 114.04 2,3,3,3-Tetrafluoropropene

Mercury Compounds

Component Name Formula CAS Number MW (g/mol) Notes
Hg Hg 7439-97-6 200.59 Elemental mercury

Ions and Electrolytes

Component Name Formula Notes
Na+ Na⁺ Sodium ion
K+ K⁺ Potassium ion
Ca++ Ca²⁺ Calcium ion
Mg++ Mg²⁺ Magnesium ion
Fe++ Fe²⁺ Ferrous ion
Ba++ Ba²⁺ Barium ion
Sr++ Sr²⁺ Strontium ion
Cl- Cl⁻ Chloride ion
SO4-- SO₄²⁻ Sulfate ion
HCO3- HCO₃⁻ Bicarbonate ion
CO3-- CO₃²⁻ Carbonate ion
OH- OH⁻ Hydroxide ion
Ac- CH₃COO⁻ Acetate ion

Plus Fractions and Pseudo-Components

NeqSim supports characterizing heavy oil fractions using TBP (True Boiling Point) pseudo-components.

Adding Plus Fractions

// Method 1: Add by boiling point and density
fluid.addTBPfraction("C7", 0.10, 95.0 / 1000.0, 0.68);   // Name, moleFrac, MW [g/mol], SG
fluid.addTBPfraction("C8", 0.08, 107.0 / 1000.0, 0.72);
fluid.addTBPfraction("C9", 0.06, 121.0 / 1000.0, 0.75);
fluid.addTBPfraction("C10+", 0.04, 200.0 / 1000.0, 0.82);

// Method 2: Using oil characterization
CharacterisationTBP characterization = new CharacterisationTBP(fluid);
characterization.characterisePlusFraction();

Plus Fraction Naming Convention

Component Description
C7 Heptanes fraction (C7 SCN)
C8 Octanes fraction
C9 Nonanes fraction
C10 Decanes fraction
C11 Undecanes fraction
C7+, C10+, C20+ Plus fraction lumps

EoS Availability by Component Type

Component Category SRK PR CPA GERG-2008 Electrolyte
Light hydrocarbons (C1-C4) ✅ ✅ ✅ ✅ ❌
Medium hydrocarbons (C5-C10) ✅ ✅ ✅ ✅ ❌
Heavy hydrocarbons (C11+) ✅ ✅ ✅ ⚠️ ❌
CO2, H2S, N2 ✅ ✅ ✅ ✅ ❌
Water ✅ ✅ ✅ ✅ ✅
Glycols (MEG, TEG) ✅ ✅ ✅ ❌ ❌
Amines (MDEA, DEA) ✅ ✅ ✅ ❌ ✅
Alcohols ✅ ✅ ✅ ❌ ❌
Ions/Electrolytes ❌ ❌ ❌ ❌ ✅
Refrigerants ✅ ✅ ✅ ⚠️ ❌
Legend: ✅ Full support ⚠️ Partial/limited ❌ Not supported

Complete Component Count by Category

Counted from the COMPTYPE column of COMP.csv:

Category COMPTYPE Count Examples
Hydrocarbons HC 238 methane, toluene, 2,4-dimethylheptane
Ions ion 62 Na+, Cl-, Ca++, SO4–
General / unclassified GEN, 0 37 assorted
Inert and light gases inert 12 N2, O2, Ar, He, H2
Other other 10  
Glycols glycol 7 MEG, DEG, TEG
Acid gases acid 7 CO2, H2S, SO2
Alcohols alcohol 6 methanol, ethanol, 1-propanol
Amines amine 4 MDEA, DEA, MEA
Water, ice, seawater, salt, chlorine, asphaltene one each 6  
Total   389 Plus unlimited TBP fractions

By structure, the hydrocarbons break down as roughly 94 paraffins, 100 naphthenes and olefins, 37 aromatics and 11 alkynes or dienes. Many are structural isomers, so a shared formula and molar mass between rows is expected rather than a duplicate.

Not usable with UMR-PRU: ethylene, C2H4, C2H4- and 5-methyl-3-heptyne have no group assignment, because no group in the set can represent a bare CH2=CH2 and the alkyne subgroup has no parameters. They work with the cubic equations of state. See the Component Database Guide for the reasoning.

Adding Custom Components

If a component is not in the database, you can add it manually:

// Add component with critical properties
fluid.addComponent("myComponent", 1.0);  // Will use default properties

// Or use TBP characterization for undefined heavy fractions
fluid.addTBPfraction("MyHeavy", 0.05, 350.0 / 1000.0, 0.88);  // MW=350, SG=0.88

See Also