Other Sources for H and S

1
Other Sources for H and S

• The enthalpy and entropy values for many gases of
  interest can also be found in tabulated or figure
  format
• OBJECTIVES
• To illustrate the use of T-S and H-S figures
• To illustrate the use of tables (e.g. steam
  table)
• To introduce the Clausius-Clapeyron and Antoine
  equations
• To introduce the concept of quality

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Where Else do You Find H and S?

• thermodynamic diagrams

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T-S diagram for water
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Steam Tables
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Steam Tables
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Two-Phase Systems

• consider the situation of a phase change at
  constant T and P

Clausius-Clapeyron
Antoine equation
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Example
Estimate the entropy change of vaporization of
water at 50 ºC. The Antoine equation for water
is
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Quality, x

• for a system consisting of a saturated vapor in
  equilibrium with its saturated liquid

where M is any extensive variable (V, S, H, G, U)
and x is the mass/mole fraction of vapor
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Example

• For a reversible, adiabatic process, steam at
  8600 kPa and 500 ºC is converted to a pressure of
  10 kPa. Determine the property and quality of
  steam at the outlet