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Chapter 16 Lecture
Chapter 16: The Second Law of Thermodynamics
© 2016 Pearson Education, Inc.
Goals for Chapter 16
• To examine the directions of thermodynamic processes.
• To study heat engines. • To overview internal combustion engines and
refrigerators. • To learn and apply the second law of
thermodynamics • To study the Carnot engine: the most efficient
heat engine.
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The Direction of a Thermodynamic Process
• Heat flows spontaneously from a "hot" object to a "cold" object.
• A process can be
• Spontaneous
• Non-spontaneous
• Reversible
• Irreversible
• In equilibrium
• Overall, there can be an increase or decrease in order.
• Devices can interconvert order/disorder/energy. © 2016 Pearson Education, Inc.
The Heat Engine – Figure 16.1
• At right, you're looking at a generic heat engine.
• In this case, the user is "tapping" the natural flow of hot to cold to remove some of the energy flow to do work.
• Example 16.1 works an example problem of this process and also calculates the efficiency of the engine.
• Refer to pages 500 and 501 in your text.
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Internal Combustion – Figure 16.4
• The internal combustion engine is an excellent example of a heat engine using a fuel to generate a hot/cold differential and do pV work during the process.
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Internal Combustion – Figures 16.5 and 16.6
• The Otto cycle and the Diesel cycle are working examples the heat engine applied to a manufactured device.
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Heat Engines Run "Backward" – Figure 16.6
• If we consider what we have seen so far from the opposite direction, we can imagine doing work in order to "force" the non-spontaneous flow of energy from a cold reservoir to a hot one.
• The efficiency of this process is like the heat engine. See pages 503 and 504 in your text.
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Heat Engines Run "Backward" – Figure 16.7 and 16.8 • The refrigerator and the air conditioner are our
most familiar examples.
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The Second Law – Figure 16.9
• It is impossible to transfer heat from a cold reservoir to a hot one without doing work.
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Sadi Carnot and an Ideal Heat Engine –Figure 16.11 • The Carnot Cycle is an ideal model of the heat engine. • Refer to Examples 16.2 and 16.3 on pages 509 and 510.
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