EGR 334 Thermodynamics Chapter 4: Section 10-12

1. EGR 334 ThermodynamicsChapter 4: Section 10-12 Lecture 18: Integrated Systems and System Analysis Quiz Today?

2. Today’s main concepts: • Be able to explain what an integrated system is • Be able to describe the components of some common integrated systems • Apply mass balance, energy balance, and continuity to streams of flow through integrated systems. Reading Assignment: • No New Reading Assignment for Wed. • Read Chap 5 for Friday. Homework Assignment: Problems from Chap 4: 95, 98, 102

3. Terms for Chap 5 Class Discussion : • Spontaneous Heat Transfer • Clausius Statement • Kelvin-Planck Statement • Entropy Statement • Irreversible vs. Reversible • Internally Reversible Process • Carnot Corollaries • Carnot Efficiency • Max. heat pump efficiency • Max. refrigeration cycle COP • Carnot Cycle • Clausius Inequality You may want to create a summary sheet to help you discuss each of the concepts.

4. System Integration • Engineers creatively combine components to achieve some overall objective, subject to constraints such as minimum total cost. This engineering activity is called system integration. • The simple vapor power plant of Fig 4.16 provides an illustration.

5. Sec 4.11: System Integration Integrated Thermodynamics Systems: System Integration : Combine components to make a useful cycle Some common systems: - Power Plant - Refrigerator - Heat Pump Components: Pipes Nozzles/Diffusers Turbines Compressors/Pumps Heat Exchanger Throttling

6. Sec 4.11: System Integration Power Plant Cycle 1. Boil Water Burn something Nuclear Reaction Geothermal 2. Use the steam as it rises to turn a turbine.

7. Sec 4.11: System Integration Power Plant Cycle 3.Condense Steam (to recycle water) using a heat exchanger 4. Pump water back to boiler.

8. Sec 4.11: System Integration Power Plant Cycle 2. Turbine 3. Condenser 4. Pump 1. Boiler

9. Sec 4.11: System Integration Power Plant Cycle • QCV 1. Boiler 2. Turbine • WCV . • WCV 4. Pump • QCV 3. Condenser

10. Sec 4.11: System Integration Refrigeration cycle 1.Condenser We know that condensing something will remove heat from the fluid. 3. Evaporator To have something to condense, we must have evaporated something. (Both are heat exchangers)

11. Sec 4.11: System Integration Refrigeration cycle 1. Condenser 4. Compressor 3. Evaporator 2. Throttling valve/ Expander

12. Sec 4.11: System Integration Refrigeration Cycle 1. Condenser • QCV 2. Throttling valve/ Expander 4. Compressor 3. Evaporator • WCV • QCV

13. Sec 4.11: System Integration • Example: (4.103) A simple gas turbine power cycle operating at steady state with air as the working substance is shown in the figure. The cycle components include an air compressor mounted on the same shaft as the turbine. The air is heated in the high-pressure heat exchanger before entering the turbine. The air exiting the turbine is cooled in the low-pressure heat exchanger before returning to the compressor. KE and PE effects are negligible. The compressor and turbine are adiabatic. Using the ideal gas model for air, determine the • Power required for the compressor, in hp, • Power output of the turbine, in hp, • Thermal efficiency of the cycle

14. Sec 4.11: System Integration • Example: (4.103) • Power required for the compressor, in hp, • Power output of the turbine, in hp, • Thermal efficiency of the cycle From Table A-22E : Ideal Gas Properties of Air • Assumptions • Steady State • KE=  PE = 0 • Turbine and compressor are Adiabatic (QCV= 0) • No work in Heat Ex. (WCV = 0) • Air is modeled as an ideal gas

15. Sec 4.11: System Integration • Example: (4.103) • Power required for the compressor, in hp, • Power output of the turbine, in hp, • Thermal efficiency of the cycle Using Continuity Eq. Ideal Gas Eq. so and

16. Sec 4.11: System Integration • Example: (4.103) • Power required for the compressor, in hp, • Power output of the turbine, in hp, • Thermal efficiency of the cycle Energy Balance (Compressor):

17. Sec 4.11: System Integration • Example: (4.103) • Power required for the compressor, in hp, • Power output of the turbine, in hp, • Thermal efficiency of the cycle Energy Balance (Same as Compressor):

18. Sec 4.11: System Integration • Example: (4.103) • Power required for the compressor, in hp, • Power output of the turbine, in hp, • Thermal efficiency of the cycle Find Q23Energy Balance around heat exchanger:

19. Sec 4.9: Heat Exchangers (Revisited) • Example: (4.78) As sketched in the figure, a condenser using river water to condense steam with a mass flow rate of 2x105 kg/h from saturated vapor to saturated liquid at a pressure of 0.1 bar is proposed for an industrial plant. Measurements indicate that several hundred meters upstream of the plant, the river has a volumetric flow rate of 2x105 m3/h and a temperature of 15°C. For operation at steady state and ignoring changes in KE and PE, determine the river-water temperature rise, in °C, downstream of the plant traceable to use of such a condenser, and comment.

20. Sec 4.9: Heat Exchangers (Revisited) • Example: (4.78) Look up intensive properties for water from Tables based on known property values From Table A-2 : Properties of Saturated Water

21. Sec 4.9: Heat Exchangers (Revisited) • Example: (4.78) Using the energy balance simplified for a heat exchanger From Table A-2 : Properties of Saturated Water (p817 & 819)

22. Sec 4.9: Heat Exchangers (Revisited) • Example: (4.78) Plugging known values: From Table A-2 : Properties of Saturated Water (p817 & 819) Using this value, the exit temperature may be found from Table A-2. TR,e = 15.6°C  giving a temperature rise of 0.6 °C

23. end of Lecture 18 Slides