Results
Pick a component or mixture, set temperature and pressure, and press Calculate. The worked examples in the Presets list are a good place to start.
Choosing a method
Reference EOS (pure fluids)
Multiparameter Helmholtz equations fitted to measured data: the same formulations behind REFPROP and the IAPWS steam tables. Densities to 0.1%, transport properties included. About 120 fluids.
Peng-Robinson / SRK
Cubic equations of state. Right for hydrocarbons, natural gas, air separation and anything near or above the critical region. Liquid densities are typically 5–10% low; vapour pressure and K-values are good.
NRTL
Activity-coefficient model for polar, non-ideal liquids at low pressure: alcohols, water, ketones, acids. Captures azeotropes when regressed binary parameters exist; the result tells you if they do not.
UNIFAC (Dortmund)
Predicts activity coefficients from functional groups, so it works for pairs nobody has measured. Less accurate than a regressed NRTL fit, far better than assuming ideality.
Model equations match those in commercial simulators; the binary-parameter bank is smaller. Missing pairs are reported in the results, not silently zeroed.