1. CHAPTER 4 The First Law of Thermodynamics

2. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 5 Slide 2 The First Law of Thermodynamics Adiabatic work System Work Transfer Surroundings Adiabatic Boundary

3. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 5 Slide 3 The First Law of Thermodynamics Equivalence of adiabatic processes Any adiabatic path can be used to connect the two states, and all adiabatic paths between the states will require the same amount of work transfer. State 1 State 2

4. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 5 Slide 4 The First Law of Thermodynamics First Law Statement The adiabatic work done on a closed system to connect two equilibrium states is independent of path.

5. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 5 Slide 5 The First Law of Thermodynamics The First Law Work done by the system is positive by convention.

6. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 5 Slide 6 The First Law of Thermodynamics Internal energy, U Work done by the system is positive by convention.  KE 1-2 = 0, and  PE 1-2 = 0.

7. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 5 Slide 7 The First Law of Thermodynamics State 1 State 2 Experimentally based, and never refuted by experiment or theory. Adiabatic Processes

8. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 2 Slide 8 The Energy Balance for Closed Systems: The First Law and Heat The Energy Balance for Closed Systems The First Law and Heat

9. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 2 Slide 9 The Energy Balance for Closed Systems: The First Law and Heat Heat: The result of non-adiabatic processes Non-adiabatic path, i.e., Q 1-2 > 0. Adiabatic path, i.e., Q 1-2 = 0. P1P1 P2P2

10. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 2 Slide 10 The Energy Balance for Closed Systems: The First Law and Heat Heat defined Heat transfer to the system: Heat transfer from the system:

11. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 2 Slide 11 The Energy Balance for Closed Systems: The First Law and Heat Energy balances...

12. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 2 Slide 12 The Energy Balance for Closed Systems: The First Law and Heat Energy Balances = Change of Energy in the System Change of Energy in the System - Heat Transfer at System Boundary Heat Transfer at System Boundary Work Done by the System Work Done by the System These terms are evaluated at the system boundary. They represent energetic interactions between the system and its surroundings.

13. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4-1 FIGURE 4–7 The energy change of a system during a process is equal to the net work and heat transfer between the system and its surroundings.

14. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 2 Slide 14 The Energy Balance for Closed Systems: The First Law and Heat Cyclic processes...

15. Cyclic Processes P1P1 P2P2 S1S1S1S1 S2S2S2S2

16. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 2 Slide 16 The Energy Balance for Closed Systems: The First Law and Heat Equivalence of heat and work This is an important result that says the cyclic heat and work are the same. It establishes that heat and work are different forms of energy.

17. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 2 Slide 17 The Energy Balance for Closed Systems: The First Law and Heat Closed system energy balance

18. Instructor’s Visual Aids Heat Work and Energy. A First Course in Thermodynamics © 2002, F. A. Kulacki Chapter 4 Module 2 Slide 18 The Energy Balance for Closed Systems: The First Law and Heat Energy balance for closed system at constant pressure