Hello!
I need to create phase diagram (PT) using PCSAFT 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?
Physical chemistry
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Re: Physical chemistry
Formulation of PCSAFT: Start by formulating the PCSAFT equation for your specific system. This will involve defining the segment numbers, chain lengths, and molecular parameters for your components.Max_{123} wrote: ↑Tue Sep 05, 2023 8:50 am Hello!
I need to create phase diagram (PT) using PCSAFT 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?
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 twophase equilibrium, you'd equate the fugacities of each component in the liquid and vapor phases.
GibbsDuhem Equation: Apply the GibbsDuhem 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 PCSAFT 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 PT phase diagram. Plotting pressure against temperature while varying composition will reveal phase boundaries and regions of singlephase and twophase regions.
Validation: Validate your results against experimental data if available to ensure the accuracy of your phase diagram.

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Re: Physical chemistry
You must identify the components, figure out their PCSAFT 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 (PT) using the PCSAFT equation.