- #1
Rafe Zayed
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How can I calculate thermodynamic property like entropy and enthalpy of 70% steam and 30% air mixture ?( at about 90 degree Celsius and 10 MPa)
Thermodynamic properties of a liquid-gas mixture
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SUMMARY
The discussion focuses on calculating the thermodynamic properties, specifically entropy and enthalpy, of a liquid-gas mixture consisting of 70% steam and 30% air at 90°C and 10 MPa. The boiling point of water at this pressure is 311°C, indicating that water will primarily exist in the liquid phase. Participants discuss the ideal gas approximation for the gas phase and the equilibrium vapor pressure of water vapor at 90°C, which is approximately 70,000 Pa. The conversation emphasizes the need to determine mass fractions and mole fractions of the components in the mixture.
PREREQUISITES- Understanding of thermodynamic properties such as entropy and enthalpy
- Knowledge of ideal gas law and its application to mixtures
- Familiarity with phase equilibrium concepts, particularly vapor-liquid equilibrium
- Basic skills in calculating mass and mole fractions in mixtures
- Learn about calculating thermodynamic properties of mixtures using the Gibbs free energy method
- Study the principles of vapor-liquid equilibrium and its applications in thermodynamics
- Explore the use of software tools like REFPROP for calculating thermodynamic properties
- Investigate the effects of pressure and temperature on phase behavior in liquid-gas mixtures
Engineers, thermodynamicists, and researchers involved in the study of fluid mixtures, particularly those working with steam and air mixtures in high-pressure environments.
- #2
JBA
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The boiling point of water at 10 Mpa is 311°C
- #3
berkeman
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Welcome to the PF.Rafe Zayed said:
This is a pretty useful website that you may find helpful in your learning: http://www.thermopedia.com/content/1150/
- #4
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Do you mean 30 mole %? Are you willing to assume that the mixture is an ideal gas mixture? What are the reference states of the air and water relative to which you desire to determine the entropy and enthalpy?
- #5
Rafe Zayed
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No I mean 30% by mass fraction.Chestermiller said:
And at this high pressure ,water will be liquid. So I am not sure whether I can treat them as gas mixture or liquid gas mixture.
Any suitable reference point will do.Basically I want to find the property of a liquid -gas mixture
- #6
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What is the equilibrium vapor pressure of water vapor at 90 C?
- #7
Rafe Zayed
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According to internet I found it to be around 70000 PaChestermiller said:
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Good. So that's about 0.07 MPa. If you're willing to tentatively approximate the gas phase as an ideal gas mixture, then that would be the partial pressure of water vapor in the gas phase. And at a total pressure of 10 MPa, what would be the mole fraction of water vapor in the gas phase? From these results, what would be the mass fractions of air and water in the gas phase? On the basis of 1 kg of water and air, what would be the mass of air? What would be the mass of water vapor in the gas phase? How much water would that leave for the liquid phase?Rafe Zayed said:
- #9
Rafe Zayed
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Sorry ,I didn't get that.At this pressure will there be any water vapour?Won't all the water vapour turn into liquid?Chestermiller said:
- #10
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Not all, but most.Rafe Zayed said:
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