2.4. Constitutive Relationships
Examples 2.1 and 2.2 required more than simple material balances to define the modeling equations. These required relationships are known as constitutive equations; several examples of constitutive equations are shown in this section.
Process systems containing a gas will often need a gas-law expression in the model. The ideal gas law is commonly used to relate pressure (P), molar volume (), and temperature (T):
The van der Waal's PT relationship contains two parameters (a and b) that are system ...