Chemical Engineering Thermodynamics

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• Chemical Engineering Thermodynamics
• Lecturer Zhenxi Jiang (Ph.D. U.K.)
• School of Chemical Engineering

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Chapter 12Solution Thermodynamics Application
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12.2 Models for the Excess Gibbs Energy

• In general GE/RT is a function of T, P, and
  composition, but for liquids at low to moderate
  pressures it is a very weak function of P.
  Therefore the pressure dependence of activity
  coefficients is usually neglected. Thus, for data
  at constant T
• 
  (const T )
• The Margules equation, Eq. (12.9), is an example
  of this functionality.

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12.2 Models for the Excess Gibbs Energy

• A number of other equations are in common use for
  correlation of activity coefficients. For binary
  systems (species 1 and 2) the function most often
  represented by an equation is ,
  which may be expressed as a power series in x1
• (const
  T )

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12.2 Models for the Excess Gibbs Energy

• Because x21-x1, mole fraction x1 serves as the
  single independent variable. An equivalent power
  series with certain advantages is known as the
  Redlich/Kister expansion
• 
  (12.14)
  
• In application, different truncations of this
  series are appropriate, and in each case specific
  expressions for ln and ln are generated
  from Eq. (11.96).

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12.2 Models for the Excess Gibbs Energy

• Because x21-x1, mole fraction x1 serves as the
  single independent variable. An equivalent power
  series with certain advantages is known as the
  Redlich/Kister expansion
• 
  (12.14)
  
• In application, different truncations of this
  series are appropriate, and in each case specific
  expressions for ln and ln are generated
  from Eq. (11.96).

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12.2 Models for the Excess Gibbs Energy
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12.2 Models for the Excess Gibbs Energy
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12.2 Models for the Excess Gibbs Energy
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12.2 Models for the Excess Gibbs Energy

• Local Composition Models

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12.2 Models for the Excess Gibbs Energy

• Local Composition Models

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12.2 Models for the Excess Gibbs Energy

• Local Composition Models

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12.2 Models for the Excess Gibbs Energy

• Local Composition Models

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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing
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12.3 Property Changes of Mixing