Physical chemistry

[Max123]

Hello!

I need to create phase diagram (P-T) using PC-SAFT equation. Which parameters I have to calculate to do this?

Is it correct that I should equate the fugitivities of the components in both phases and if the equation has a solution then they exist, if not then the system is single phase?

[Weser]

Hello!

I need to create phase diagram (P-T) using PC-SAFT equation. Which parameters I have to calculate to do this?

Is it correct that I should equate the fugitivities of the components in both phases and if the equation has a solution then they exist, if not then the system is single phase?

Formulation of PC-SAFT: Start by formulating the PC-SAFT equation for your specific system. This will involve defining the segment numbers, chain lengths, and molecular parameters for your components.
Equilibrium Conditions: To determine phase equilibria, you're correct that you should equate the fugacities of the components in both phases. The fugacity is a measure of the escaping tendency of a component from the mixture. For a two-phase equilibrium, you'd equate the fugacities of each component in the liquid and vapor phases.
Gibbs-Duhem Equation: Apply the Gibbs-Duhem equation to relate changes in pressure, temperature, and composition for coexisting phases. This equation helps in calculating the phase equilibrium conditions.
Parameter Estimation: You may need to estimate or obtain PC-SAFT parameters for your specific components, which can involve experimental data or theoretical calculations.
Numerical Methods: Solve the equations numerically. Various numerical methods like Gibbs energy minimization or flash calculations may be used.
Construction of Phase Diagram: With the obtained data, construct your P-T phase diagram. Plotting pressure against temperature while varying composition will reveal phase boundaries and regions of single-phase and two-phase regions.
Validation: Validate your results against experimental data if available to ensure the accuracy of your phase diagram.

[jesse99]

You must identify the components, figure out their PC-SAFT parameters, and compare the component fugacities in both phases at various temperature (T) and pressure (P) points to determine phase equilibrium in order to build a phase diagram (P-T) using the PC-SAFT equation.