The FluidFlow database contains a number of gas mixtures such as natural gas and you can very easily create new mixtures in the fluids database by selecting:
1. Database | Fluids.
2. Select the "NEW MIX" button.
3. Add the various component fluids to your new mixture.
The image below gives an overview of some of the natural gas mixtures included in the fluids database:
In relation to predicting local condensation (like a rapid depressurization), the J-T coefficient together with cooling effects due to loss of static pressure make this prediction of temperature and degree of condensation accurate for pure fluids and petroleum fraction gases. When modeling multi-component fluids, although accurate, the level of accuracy is slightly lower than that of pure component fluids.
Gas mixtures can also be created dynamically on the Flowsheet.
Note, FluidFlow uses a generalized Equation of State and Plocker mixing rules for estimating the physical properties of gas mixtures.