### 12.4.1. Using a Real Gas Equation of State

This method is only appropriate for vapor-liquid phase change and cannot be used for other types of phase change. It is required that each material in the mixture uses the same Real Gas equation of state with all the appropriate data set. CFX presupplies a number of suitable materials, which are categorized into several groups, that contain three materials for each pure substance. In each group the vapor material has a “v” at the end of the material name, the liquid has an “l” and the homogeneous binary mixture has a “vl” at the end.

#### 12.4.1.1. Redlich Kwong Wet Steam

Only water vapor, liquid water and the homogeneous binary mixture of the two phases appear in this group. Material is suitable for condensing steam flows with small liquid mass fractions.

#### 12.4.1.2. Redlich Kwong Wet Refrigerants

This group contains several refrigerants including , , , , , , , , , , , , , , , , and .

is modeled using critical point properties, acentric factor and ideal gas specific heat coefficients obtained from NIST REFPROP V7.0 assuming a fixed composition of 50% R32 and 50% R125 by mass.

#### 12.4.1.3. Redlich Kwong Wet Hydrocarbons

This group contains a variety of common hydrocarbons including Methane (), Acetylene (), Ethene (), Ethane (), Ethanol (), Propene (), Propane (), 1-Butyne (), Cyclobutane (), Butane (), Pentane (), Benzene (), Hexane (), Toluene (), Octane (), Nonane (), and Decane ().

#### 12.4.1.4. Wet Redlich Kwong

This group contains various pure fluids that do not appear in the other groups and includes Argon, Carbon Monoxide, Carbon Dioxide, Chlorine, Deuterium, Fluorine, Hydrogen, Hydrogen Sulfide, Helium, Nitrogen, Neon, Oxygen, Para-Hydrogen, Sulfur Dioxide and Ozone.

#### 12.4.1.5. Creating a Liquid Phase Material

If you have already created a vapor phase material, then an easy way to set the data for the liquid phase material is to make a copy of the vapor phase material, change the name to something appropriate, and then simply update the Thermodynamic State to Liquid instead of Gas.

#### 12.4.1.6. Creating the Homogeneous Binary Mixture

When creating the Homogeneous Binary Mixture, select the two materials that make up the mixture in the Material 1 and Material 2 fields. The thermodynamic state of one fluid should be liquid and the thermodynamic state of the other should be gas. Under Saturation Properties, set the Option to `Redlich Kwong`. No other option is available or valid.

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