VLE Input
Pressure is entered in mm Hg abs and internally converted to bar abs for the equilibrium calculation. 1 bar = 750.0617 mm Hg.
Calculation basis: NRTL activity coefficients with constant A12/A21 parameters from the ChemJunction V2 database. Pure-component vapour pressure is calculated from the embedded Antoine coefficients. The low-pressure calculation uses the γ-φ / ideal-gas-vapour approximation, i.e. yᵢP = xᵢγᵢPᵢ°(T). Pressure is the independent operating variable; temperature is solved from phase equilibrium. Results are engineering screening calculations and should be validated against experimental VLE data before design use.
Pair—
ModelNRTL
Points—
Operating pressure (mm Hg abs)—
StatusReady
Pressure-Dependent VLE Charts
Mole-Fraction x-y
Mass-Fraction x-y
All three charts are generated at the selected operating pressure. Temperature is calculated along the equilibrium curve and is not an input.
Mole Fraction Results
Mass Fraction Results
Engineering Calculation Basis
- NRTL: τij = Aij/(RT), with R = 1.987204 cal/mol·K.
- Gij = exp(-αijτij).
- At each liquid composition and selected pressure: yiP = xiγiPisat(T).
- At the selected pressure, the bubble temperature is solved by ΣxiγiPisat(T) = P.
- Mass fractions are calculated from mole fractions using molecular weights.
- Binary interaction parameters are source records; alternate literature fits are not silently averaged.