Thermocal

PR-EOS DENSITY, Cp, FLASH & JT CALCULATOR

Peng-Robinson (1978) · C1/C2/C2=/C3/C3= · Pure & Mixture

Conditions

Temperature

Unit °C K °F

Pressure

Unit atm bar barg kPa kg/cm²g psia

Phase (which cubic root to report)

Composition

	Component	zi

Sum: 1.0000

Tick a component to include it in the mixture. Newly ticked components start at 0 — enter a value.

Results

Enter conditions and composition, then click Calculate.

Model: Peng-Robinson (1978) cubic EOS, van der Waals one-fluid mixing rules, literature/simulator-default binary interaction parameters (k_ij) for light hydrocarbon pairs. Ideal-gas Cp from Reid/Prausnitz/Poling polynomials (Cp° = A + BT + CT² + DT³); real-gas Cp includes PR departure function. Liquid-phase density from PR EOS without volume translation — expect ~2–5% deviation from measured saturated-liquid density; cross-check against plant data or a process simulator for custody-transfer / fiscal use. Not a substitute for validated process simulation for safety-critical design.

IBP / FBP (mixtures only): bubble-point and dew-point temperature at the input pressure, found via the PR-EOS flash engine. Flash Point is a theoretical estimate using Antoine vapor pressures and the Le Chatelier lower-flammability-limit (LFL) mixing rule at 1 atm, approximating liquid composition ≈ feed composition — it is not a substitute for a laboratory-measured flash point (ASTM D56/D93/D3278) and should not be used as the sole basis for fire-safety classification or regulatory compliance.

Extended component set (1,3-butadiene, n-butane, C5H10/1-pentene, benzene, toluene, n-hexane, methanol, VCM, EDC, HCl, chlorine, EO, EG): critical properties (T_c, P_c, ω) are literature-typical values, and untabulated binary pairs default to k_ij=0 (ideal mixing) — verify against DIPPR/NIST/a process simulator before design or safety use. Saturation-temperature (Antoine) and Flash Point estimates are not yet available for these components (density, Cp, and JT/enthalpy calculations are unaffected).

Inlet / Outlet Conditions

Inlet Temperature, T1

Unit °C K °F

Inlet Pressure, P1

Unit atm bar barg kPa kg/cm²g psia

Outlet Pressure, P2

Unit atm bar barg kPa kg/cm²g psia

Adiabatic, isenthalpic (H₁=H₂) pressure reduction — e.g. across a control valve or PRV. P2 must be less than P1. Solves for outlet T2 such that real-gas enthalpy (PR EOS departure + ideal-gas Cp integral) is conserved.

Feed Composition

	Component	zi

Sum: 1.0000

Tick a component to include it in the feed. Newly ticked components start at 0 — enter a value.

Results

Enter conditions and feed composition, then click Calculate T2.

Method: (1) Flash the feed at (T1,P1) via PR-EOS fugacities to get inlet molar enthalpy H1 = ideal-gas Cp integral + phase-fraction-weighted PR departure function. (2) Search T2 at P2 by bisection until H(T2,P2) = H1. For a pure component, phase change at fixed P happens at a single saturation temperature (a true latent-heat jump in H, not a smooth kink) — so if H1 falls between the saturated-liquid and saturated-vapor enthalpies at T_sat(P2), the outlet is exactly at T_sat(P2) with vapor fraction from an enthalpy lever-rule balance, rather than from a naive continuous T-search (which would straddle the discontinuity incorrectly). For a mixture, the two-phase region spans a continuous range of T at fixed P, so direct bisection on T finds the two-phase solution directly.

For extended-set pure components without a loaded Antoine correlation, the saturation-temperature clamp at T_sat(P2) is skipped and the solver goes straight to bisection on T — this is fine away from a phase change, but can be less precise exactly at one.

Reference Conditions (volumetric basis)

Reference Temperature 0 °C (Nm³, normal conditions) 15 °C (Sm³, GPA/typical standard) 15.56 °C (60 °F) 20 °C 25 °C

Molar and mass-basis calorific values don't depend on this choice. Reference pressure fixed at 1 atm (101.325 kPa). Volumetric conversion uses the ideal-gas law — a simplified version of the real-gas compressibility (summation-factor) correction in full ISO 6976 / GPA 2172; adequate for typical fuel-gas heating value estimates but not for custody-transfer-grade certification.

Composition

	Component	zi

Sum: 1.0000

Tick a component to include it in the mixture. Newly ticked components start at 0 — enter a value.

Results

Enter composition, then click Calculate.

Method: Molar GCV/NCV = Σ z_i·(GCV or NCV)_i, using standard ideal-gas heats of combustion at 25°C (GPA 2145 / ISO 6976-consistent values; product water liquid for GCV/gross/HHV, vapor for NCV/net/LHV). Mass basis divides by mixture MW. Volumetric basis divides by the ideal-gas molar volume at the selected reference conditions. Specific gravity is mixture MW over dry-air MW (28.9647 g/mol); Wobbe Index = volumetric CV / √(specific gravity). Oxygen, Nitrogen, and Water are treated as inert (zero heating value) — they dilute the mixture but don't consume heat in this convention.

Extended-set heats of combustion (butadiene, butane, C5H10, benzene, toluene, hexane, methanol, VCM, EDC, EO, EG) are approximate literature values; HCl and Chlorine are treated as inert (zero heating value) since they don't combust. Chlorinated species form HCl on combustion rather than only CO2/H2O, so treat their listed values as indicative only — verify before fiscal/custody use.

Stream 1 — Conditions

Temperature

Unit °C K °F

Pressure

Unit atm bar barg kPa kg/cm²g psia

Phase (declared inlet state)

Flow rate

Unit kmol/h kg/h

Stream 1 — Composition

	Component	zi

Sum: 1.0000

Tick a component to include it in Stream 1.

Stream 2 — Conditions

Temperature

Unit °C K °F

Pressure

Unit atm bar barg kPa kg/cm²g psia

Phase (declared inlet state)

Flow rate

Unit kmol/h kg/h

Stream 2 — Composition

	Component	zi

Sum: 1.0000

Tick a component to include it in Stream 2.

Mixed Outlet — Pressure

Final (mixed) pressure

Unit atm bar barg kPa kg/cm²g psia

Outlet temperature is solved from an adiabatic, steady-state energy balance (F₁H₁+F₂H₂=F_totalH_mix) at this pressure — it is not an input.

Results

Enter both streams' conditions and composition, then click Calculate Mix.

Method: each inlet stream's molar enthalpy is evaluated at its own T, P, and declared phase (ideal-gas Cp° integral + PR-EOS departure, same convention as the Density & Cp tab). The two streams are combined on a molar basis into a single feed composition, and the outlet temperature at the specified final pressure is found by solving the steady-state, adiabatic energy balance F₁H₁ + F₂H₂ = F_total·H_mix(T,P_f). No heat loss, no shaft work, and no pressure-drop-induced flashing beyond what the energy balance itself predicts are assumed (a real tee/header may lose heat to ambient or have a different pressure profile).

The outlet phase (vapor / liquid / two-phase) is not assumed — it is determined rigorously from a PT flash (Rachford-Rice + PR fugacity coefficients) on the combined composition at the solved temperature and specified pressure, exactly as in the Isenthalpic (JT) tab. If the result is two-phase, vapor and liquid density/Cp are reported separately in addition to the flow-weighted apparent values.