1. Power and Refrigeration Systems
Fundamentals of Thermodynamics
Chapter 9
Power and Refrigeration Systems
With Phase Change

2. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.1 Introduction to power systems

3. Chapter 9. Power and Refrigeration Systems – With Phase Change

4. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.2 The Rankine cycle

5. Chapter 9. Power and Refrigeration Systems – With Phase Change

6. Chapter 9. Power and Refrigeration Systems – With Phase Change

7. Chapter 9. Power and Refrigeration Systems – With Phase Change
Determine the efficiency of a Rankine cycle using steam as the working fluid in which the condenser pressure is 10 kPa. The boiler pressure is 2 MPa. The steam leaves the boiler as saturated vapor.
Ex.
9.1

8. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.3 Effect of pressure and temperature on the Rankine cycle
i) Exhaust pressure ↓

9. Chapter 9. Power and Refrigeration Systems – With Phase Change
ii) Superheating

10. Chapter 9. Power and Refrigeration Systems – With Phase Change
iii) Boiler pressure ↑

11. Chapter 9. Power and Refrigeration Systems – With Phase Change

12. Chapter 9. Power and Refrigeration Systems – With Phase Change
In a Rankine cycle, steam leaves the boiler and enters the turbine at 4 MPa and 400℃. The condenser pressure is 10 kPa. Determine the cycle efficiency.
Ex.
9.2

13. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.4 The Reheat cycle

14. Chapter 9. Power and Refrigeration Systems – With Phase Change
Consider a reheat cycle utilizing steam. Steam leaves the boiler and enters the turbine at 4 MPa, 400℃. After expansion in the turbine to 400 kPa, the steam is reheated to 400℃ and then expanded in the low-pressure turbine to 10 kPa. Determine the cycle efficiency.
Ex.
9.3

15. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.5 The Regenerative cycle and feedwater heaters

16. Chapter 9. Power and Refrigeration Systems – With Phase Change
Ideal regenerative cycle – Carnot cycle과 동일한 열효율

17. Chapter 9. Power and Refrigeration Systems – With Phase Change
Regenerative cycle with open feedwater heater

18. Chapter 9. Power and Refrigeration Systems – With Phase Change
Consider a regenerative cycle using steam as the working fluid. Steam leaves the boiler and enters the turbine at 4 MPa, 400℃. After expansion to 400 kPa, some of the steam is extracted from the turbine to heat the feedwater in an open FWH. The pressure in the FWH is 400 kPa, and the water leaving it is saturated liquid at 400 kPa. The steam not extracted expands to 10 kPa. Determine the cycle efficiency.
Ex.
9.4

19. Chapter 9. Power and Refrigeration Systems – With Phase Change
Regenerative cycle with closed feedwater heater

20. Chapter 9. Power and Refrigeration Systems – With Phase Change
Actual power plant utilizing regenerative feedwater heaters

21. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.6 Deviation of actual cycles from ideal cycles

22. Chapter 9. Power and Refrigeration Systems – With Phase Change

23. Chapter 9. Power and Refrigeration Systems – With Phase Change
A steam power plant operates on a cycle with pressures and temperatures as designated in Fig The efficiency of the turbine is 86%, and the efficiency of the pump is 80%. Determine the thermal efficiency of this cycle.
Ex.
9.5

24. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.7 Combined heat and power: other configurations
Cogeneration system (열병합 발전) : Electricity & Heat

25. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.8 Introduction to refrigeration systems

26. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.9 The vapor-compression refrigeration cycle

27. Chapter 9. Power and Refrigeration Systems – With Phase Change

28. Chapter 9. Power and Refrigeration Systems – With Phase Change
Consider a refrigeration cycle that uses R-134a as the working fluid. The temperature of the refrigerant in the evaporator is -20℃, and in the condenser it is 40℃. The refrigerant is circulated at the rate of 0.03 kg/s. Determine the COP and the capacity of the plant in rate of refrigeration.
Ex.
9.6

29. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.10 Working fluids for vapor-compression refrigeration systems

30. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.11 Deviation of the actual vapor-compression refrigeration
cycle from the ideal cycle

31. Chapter 9. Power and Refrigeration Systems – With Phase Change
A refrigeration cycle utilizes R-134a as the working fluid. The following are the properties at various points of the cycle designated in Fig. 9.24:
Ex.
9.7
P1 = 125 kPa
P2 = 1.2 MPa
P3 = 1.19 MPa,
P4 = 1.16 MPa,
P5 = 1.15 MPa,
P6 = P7 = 140 kPa,
P8 = 130 kPa
T1 = -10℃
T2 = 100℃
T3 = 80℃
T4 = 45℃
T5 = 40℃
x6 = x7
T8 = -20℃
The heat transfer from R-134a during the compression process is 4 kJ/kg. Determine the COP of this cycle.

32. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.12 Refrigeration cycle configurations

33. Chapter 9. Power and Refrigeration Systems – With Phase Change

34. Chapter 9. Power and Refrigeration Systems – With Phase Change
9.13 The ammonia-absorption refrigeration cycle

35. Chapter 9. Power and Refrigeration Systems – With Phase Change
Homework Problems
-2017: 16, 35, 52, 68, 75