Engineering Utilities Reference

NeqSim includes a suite of engineering utilities designed to accelerate thermodynamic and process simulation workflows. These utilities reduce boilerplate, improve reproducibility, and enable AI-driven task solving.

FluidBuilder — Fluent Fluid Creation

Package: neqsim.thermo.system

Create thermodynamic fluids with a fluent API or use preset industry compositions.

Fluent API

SystemInterface fluid = FluidBuilder.create(273.15 + 25.0, 60.0)
    .addComponent("methane", 0.85)
    .addComponent("ethane", 0.10)
    .addComponent("propane", 0.05)
    .withMixingRule("classic")
    .build();

With EOS Selection

SystemInterface fluid = FluidBuilder.create(273.15 + 80.0, 200.0)
    .withEOS(FluidBuilder.EOSType.PR)
    .addComponent("methane", 0.50)
    .addComponent("n-hexane", 0.50)
    .withMixingRule("classic")
    .withMultiPhaseCheck()
    .build();

Oil Characterization

SystemInterface oil = FluidBuilder.create(273.15 + 80.0, 250.0)
    .withEOS(FluidBuilder.EOSType.PR)
    .addComponent("methane", 0.30)
    .addComponent("ethane", 0.08)
    .addTBPFraction("C7", 0.06, 0.092, 0.727)
    .addTBPFraction("C8", 0.05, 0.104, 0.749)
    .addPlusFraction("C20", 0.23, 0.350, 0.88)
    .withLumpedComponents(6)
    .withMixingRule("classic")
    .build();

Preset Fluids

Method	Description	EOS
`leanNaturalGas(T, P)`	Dry gas, 85% CH4	SRK
`richNaturalGas(T, P)`	Wet gas, 72% CH4 + C3+	SRK
`typicalBlackOil(T, P)`	Black oil with C7-C20+	PR
`gasCondensate(T, P)`	Condensate with C7-C15+	SRK
`dryExportGas(T, P)`	Pipeline gas, 92% CH4	SRK
`co2Rich(T, P)`	CCS stream, 95% CO2	SRK-CPA
`acidGas(T, P)`	Sour gas with H2S + CO2	SRK-CPA

HeatMaterialBalance — HMB Reports

Package: neqsim.process.util.report

Generate industry-standard Heat and Material Balance reports from any ProcessSystem.

ProcessSystem process = ...;
process.run();

HeatMaterialBalance hmb = new HeatMaterialBalance(process);
String json = hmb.toJson();        // Full JSON report
String csv = hmb.streamTableToCSV(); // Stream table as CSV

Customisation

hmb.setTemperatureUnit("K")
   .setPressureUnit("barg")
   .setFlowUnit("kg/sec");

Output Structure

The JSON contains:

streamTable — all streams with T, P, flow, composition, density, enthalpy, entropy, vapour fraction
equipmentSummary — compressor power, heater/cooler duty, heat exchanger UA

SensitivityAnalysis — Parameter Sweeps

Package: neqsim.process.util.optimizer

Vary one parameter across a range while tracking multiple outputs.

SensitivityAnalysis sa = new SensitivityAnalysis(process);

sa.setParameter("Outlet Pressure", 70.0, 150.0, 8,
    (proc, val) -> {
        Compressor c = (Compressor) proc.getUnit("Comp");
        c.setOutletPressure(val);
    });

sa.addOutput("Power (kW)", proc -> {
    Compressor c = (Compressor) proc.getUnit("Comp");
    return c.getPower("kW");
});

SensitivityAnalysis.SensitivityResult result = sa.run();
System.out.println(result.toJson());

Each evaluation runs on a fresh copy of the process to avoid state contamination.

MonteCarloSimulator — Uncertainty Analysis

Package: neqsim.process.util.optimizer

Run N Monte Carlo iterations with triangular or uniform distributions.

MonteCarloSimulator mc = new MonteCarloSimulator(process, 200);
mc.setSeed(42);

mc.addTriangularParameter("Gas Price", 0.8, 1.5, 2.5,
    (proc, val) -> { /* apply to process */ });

mc.addUniformParameter("CAPEX multiplier", 0.85, 1.4,
    (proc, val) -> { /* apply to process */ });

mc.setOutputExtractor("NPV (MNOK)", proc -> calculateNPV(proc));

MonteCarloSimulator.MonteCarloResult result = mc.run();
System.out.println("P10=" + result.getP10());
System.out.println("P50=" + result.getP50());
System.out.println("P90=" + result.getP90());
System.out.println("Mean=" + result.getMean());
System.out.println("P(NPV<0)=" + result.getProbabilityBelow(0));
System.out.println(result.toJson());

Tornado Sensitivity

Tornado data is automatically computed by varying each parameter individually between its low and high bounds. Access via result.getTornado().

ConvergenceDiagnostics — Troubleshooting

Package: neqsim.process.equipment.util

Diagnose convergence issues in processes with recycle loops and adjusters.

ConvergenceDiagnostics diag = new ConvergenceDiagnostics(process);
ConvergenceDiagnostics.DiagnosticReport report = diag.analyze();

if (!report.isConverged()) {
    for (String suggestion : report.getSuggestions()) {
        System.out.println("  -> " + suggestion);
    }
}
System.out.println(report.toJson());

What It Checks

Recycle units: flow, temperature, pressure, composition errors vs tolerances
Adjuster units: error vs tolerance
Identifies the dominant error type (flow, temperature, composition, etc.)
Generates actionable remediation suggestions

HydrateRiskMapper — Pipeline Hydrate Assessment

Package: neqsim.pvtsimulation.flowassurance

Map hydrate formation risk along a pipeline P-T profile.

HydrateRiskMapper mapper = new HydrateRiskMapper(fluid);

// Add pipeline profile (km, bara, °C)
mapper.addProfilePoint(0.0, 100.0, 60.0);
mapper.addProfilePoint(10.0, 95.0, 40.0);
mapper.addProfilePoint(50.0, 75.0, 4.0);

HydrateRiskMapper.RiskProfile profile = mapper.calculate();

for (HydrateRiskMapper.RiskPoint rp : profile.getPoints()) {
    System.out.printf("%.1f km: %s (subcooling=%.1f°C)%n",
        rp.distanceKm, rp.riskLevel, rp.subcoolingC);
}
System.out.println(profile.toJson());

Risk Levels

Subcooling is defined as T_actual - T_hydrate. Positive values mean the operating temperature is safely above the hydrate formation temperature.

Level	Condition (default thresholds)	Meaning
CRITICAL	T_actual < T_hydrate (margin < 0°C)	Inside hydrate zone — immediate action
HIGH	Margin 0–3°C above hydrate T	Close to hydrate curve — mitigation needed
MEDIUM	Margin 3–6°C above hydrate T	Moderate margin — monitor
LOW	Margin > 6°C above hydrate T	Safe

Custom thresholds: mapper.setRiskThresholds(3.0, 6.0) (highRiskC, mediumRiskC)

EOSComparison — Model Comparison

Package: neqsim.integration

Compare thermodynamic properties across multiple equations of state.

EOSComparison comp = new EOSComparison();
comp.addComponent("methane", 0.85);
comp.addComponent("ethane", 0.10);
comp.addComponent("propane", 0.05);
comp.setConditions(273.15 + 25.0, 60.0);
comp.setEOSTypes(EOSComparison.EOSType.SRK,
    EOSComparison.EOSType.PR,
    EOSComparison.EOSType.GERG2008);

EOSComparison.ComparisonResult result = comp.compare();
System.out.println(result.toJson());

// Check property deviations
double densityDev = result.getMaxDeviation("density");
System.out.println("Max density deviation: " + densityDev + "%");

Available Properties

density, Z, gasDensity, gasViscosity, gasZ, gasCp, oilDensity, oilViscosity, enthalpy, entropy

Supported EOS Types

SRK, PR, SRK-CPA, GERG-2008