1 / 30

Two-phase behavior

rumor
Download Presentation

Two-phase behavior

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Two-phase behavior

    2. Behavior in the two phase region

    4. Antoine’s Equation Antoines equation is used to predict the relationship between the T and P in the two phase region. P is usually called saturation pressure and T is usually called the vaporization temperature or vice-versa For propane, the Antoines constants are A = 6.80398, B =803.81, C= 246.99 (Psat in mmHg) Calculate the vapor pressure for propane at 100, 200, 300 K and the critical point 369.8 K. Compare to the values from the chart.

    5. Antoine’s Equation

    6. Gibbs Free energy

    7. Relationship of V and S

    9. Finding the slope of Psat vs Tvap

    10. Change in Psat with T

    11. Numerical (Easier) Estimating the slope of Psat vs Tvap at a particular T.

    12. DSvap Given the Antoine’s constants, one can calculate the way the saturation pressure changes with Tvap at any Tvap. One can use an EOS to estimate Vvap and Vliq at that temperature Tvap.(eg 10-24 PR) From the difference in Vvap and Vliq one can obtain Svap – Sliq (DSvap)

    13. Shortcut Approximations Since Vliq << Vvap, a shortcut is to find only Vvap Since Vvap ~ RT/P

    14. Calculation of DSvap from dPsat/dTvap

    15. Calculation of DHvap Since along the two phase region:

    17. Clausius-Clapeyron Eq

    18. Clausius-Clapeyron

    20. Summary In the two phase region, there is an explicit relationship between P and T. As T increases so does the vapor pressure, according to Antoine’s equation. The relationship between Pvap and Tsat can be used to compute the difference in the vapor and liquid volumes, entropy, and enthalpy.

    21. Gibbs Phase Rule

    22. Single Phase

    23. 2-phase Region

    24. Two phase region

    25. 2 Components – Two phases

    26. Phase Rule in Multicomponent Systems

    27. 3 phases

    28. Triple Point

    29. “Stability Analysis”

    30. Summary There is an explicit “rule” that relates the number of “degrees of freedom” of multiphase and multicomponent systems at equilibrium. This rule tells one how many of the “intensive” variables in a system can be independently specified, which keeps one’s thoughts organized about systems

More Related