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

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

Chapter 9. Power and Refrigeration Systems – With Phase Change

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

Chapter 9. Power and Refrigeration Systems – With Phase Change

Chapter 9. Power and Refrigeration Systems – With Phase Change

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

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

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

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

Chapter 9. Power and Refrigeration Systems – With Phase Change

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

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

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

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

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

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

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

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

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

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

Chapter 9. Power and Refrigeration Systems – With Phase Change

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. 9.17. 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

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

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

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

Chapter 9. Power and Refrigeration Systems – With Phase Change

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

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

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

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.

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

Chapter 9. Power and Refrigeration Systems – With Phase Change

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

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