Engineering Applications of Control Volume-2

1. Engineering Applications of Control Volume-2 P M V Subbarao Professor Mechanical Engineering Department More Innovations for Extrasomatism…..

2. Steam Power Plant: A series of CVs in SSSF

3. Pumping of Incompressible Fluids Adiabatic pumping of a liquid is almost an Isothermal process!!

4. 2 – 3 : Steam Generation : Isobaric Heating QCV No work transfer, change in kinetic and potential energies are negligible

5. Oil Fired Steam Boiler

6. Turbine : Adiabatic Process 3 T 4 No heat transfer. Change in kinetic and potential energies are negligible Assuming a single fluid entering and leaving…

7. Diagram of Large Power Plant Turbine

8. HP Turbine Rotor

9. LP Turbine Rotor

10. Highly compressible flow through Turbine

11. Steam Power Plant: A series of CVs in SSSF

12. 4 – 1 : Condenser : Isobaric Cooling : p4 = p1 QCV 4 1 No work transfer, change in kinetic and potential energies are negligible Assuming a single fluid entering and leaving…

15. Schematic for PC Power Plant with cooling Water from A River

16. Windcatcher (Bagdir)

17. Schematic for PC Power Plant with cooling tower

18. Air Cooled Condenser System

19. Net Heat and work Actions • First law for a cycle:

20. Turbojet Engine: A Heat Engine with Single Phase –Non Pure Substance Qin Qout Wout

21. Structure of A Domestic Refrigerator 1: Evaporator/Freezer 2: Condenser 3: Compressor 4 : Throttling Device

22. Thermodynamic Cycle of A Refrigerator

24. Throttling Valve Compressor Simplified Diagram of A Refrigerator Condenser : Transient Constant Pressure Cooling. Compressor : Transient adiabatic Compression. Throttling Device: Homogeneous and Transient Isoenthalpic process. Evaporator: Transient Constant Pressure Cooling. All the parts are CVs working in USUF processes.

25. Analysis of Uniform State Uniform Flow Devices

26. First Law for CV:Uniform State Uniform Flow Properties of CV are variant: • Conservation of mass: Continuous Accumulation or/and depletion of mass of a CV. • Conservation of energy: Continual Addition or removal of energy for a CV.

27. Salient Features of CV @USUF Process • Rate of mass inflow  Rate mass outflow. • The states of inflows and outflows are invariant although the mass flow rates may be time varying. • Rate of Work done is variant. • Rate of Heat transfer is variant. • Change of state or process is both for the CV and Flows! • The incoming fluid changes its state from inlet(at one time t0) to exit (at time t0+Dt) condition. • A CV with USUF process is approximates as a homogeneous but variant device. • The importance of time is very high!

28. CV following A USUF Process for time Dt • A change of state occurs in a CV with USUF due to change in time. • A total change in a CV over time Dt can be calculated using: Total change in mass of A CV during a time interval Dt

29. Total change in energy of A CV during a time interval Dt All parameters mentioned above are homogeneous and variant.

30. Let us now integrate this equation over time Dt, during which time we have

31. First Law for A CV executing USUF for finite time

32. Throttling Devices • Throttling devices are any kind of flow restricting devices. • They cause large pressure drop in the fluid. • The pressure drop in fluid is often accompanied by a large drop in temperature and rarely a raise in temperature. • The magnitude of temperature drop or rise during a throttling process is governed by a property called Joule-Thomson Coefficient.

33. 0 0 Throttling Valves • Throttling: Reduces Pressure • Common Assumptions: • SSSF • No work or heat transfer • Neglect changes in PE and KE • Energy Balance: Throttling Valve

34. Isenthalpic (h = constant) Process Internal energy + Flow energy = Constant The fluids whose pv increases during throttling generate cooling effect. The fluids whose pv decreases during throttling generate cooling effect

35. The Joule-Thomson Experiment