1. 7.7 The Tds Relations

2. The T-ds equations...

3. The T-dS equations
Note that the specific heats are generally a function of temperature.

4. Isentropic processes - ideal gasesv

5. 7.9 The Entropy Change of Ideal Gases

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FIGURE 7-36 The isentropic relations of ideal gases are valid for the isentropic processes of ideal gases only.

7. 7.10 Reversible Steady-Flow Work

8. FIGURE 7-43 Schematic and T-s diagram for Example 6–12.
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FIGURE 7-43 Schematic and T-s diagram for Example 6–12.

9. 7.11 Minimizing the Compressor Work

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FIGURE 7-45 P-v diagrams of isentropic, polytropic, and isothermal compression processes between the same pressure limits.

11. Multistage Compression with Intercooling

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FIGURE 7-46 P-v and T-s diagrams for a two-stage steady-flow compression process.

13. 7.12 Isentropic Efficiencies of Steady-Flow Devices

14. Isentropic efficiency
Common open system components
Nozzles
Compressors
Turbines
Pumps
The concept of isentropic efficiency comes from the combination of the 1st and 2nd Laws.

15. h-s diagram Isentropic process, s = constant,
Maximum enthalpy change., p1 p2 1 2 h s
s1 = s2
Al accessible states lie
to the right of this line.

16. Isentropic efficiencyh s p2 p1
h2,s h2 h1
Isentropic expansion, entropy
production is zero.
Actual expansion, h2 < h2,s

17. Turbines and compressors
Irreversible h s
p2 > p1
Compressor
Turbine
Reversible,
adiabatic
Reversible,
adiabatic

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FIGURE 7-49 The h-s diagram for the actual and isentropic processes of an adiabatic turbine.

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FIGURE 7-51 The h-s diagram of the actual and isentropic processes of an adiabatic compressor.

20. FIGURE 7-53 Schematic and T-s diagram for Example 6–15.
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FIGURE 7-53 Schematic and T-s diagram for Example 6–15.

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FIGURE 7-54 The h-s diagram of the actual and isentropic processes of an adiabatic nozzle.