1. Thermodynamics Lecture Series email: drjjlanita@hotmail.com http://www5.uitm.edu.my/faculties/fsg/drjj1. htmldrjjlanita@hotmail.com Applied Sciences Education Research Group (ASERG) Faculty of Applied Sciences Universiti Teknologi MARA First Law – Control Volume

2. First Law - Quotes “Education is not the piling on of learning, information, data, facts, skills, or abilities--that's training or instruction--but is rather a making visible what is hidden as a seed... To be educated, a person doesn't have to know much or be informed, but he or she does have to have been exposed vulnerably to the transformative events of an engaged human life... One of the greatest problems of our time is that many are schooled but few are educated.” Author:Thomas Moore Source:he Education of the Heart by Thomas Moore Quote

3. Introduction - Objectives 1.State the conservation of mass principle. 2.State the meaning of steady-flow process and the implications on a system’s properties. 3.Write the unit-mass basis and unit-time basis (or rate-form basis) energy balance for a general steady-flow process. 4.Write the unit-time basis (or rate-form basis) mass balance for a general steady-flow process. Objectives:

4. Introduction - Objectives 4.State the assumptions for steady-flow devices such as nozzles, diffusers, turbines, compressors, throttle valves, heat exchangers and mixing chambers. 5.State the purpose for each of the steady-flow device noted above. 6.Write the unit-mass basis and unit-time basis (or rate-form basis) energy balance for each of the steady-flow devices noted above Objectives:

5. Introduction - Objectives 7.Write the unit-time basis (or rate-form basis) mass balance for each of the steady-flow device. 8.Use the energy and mass balance to solve problems related to each of the steady-flow device. Objectives:

6. First Law - General Control Volume Open System Steady-flow Devices

7. First Law - General How to relate changes to the cause Dynamic Energies as causes (agents) of change System E 1, P 1, T 1, V 1 To E 2, P 2, T 2, V 2 Properties will change indicating change of state Mass out Mass in W in W out Q in Q out

8. First Law – Energy Balance Energy Balance Amount of energy causing change change must be equal to amount of energy change change of system Energy Entering a system - Energy Leaving a system = Change of system’s energy

9. First Law – Energy Balance Energy Balance E in – E out =  E sys, kJ or e in – e out =  e sys, kJ/kg or Energy Entering a system - Energy Leaving a system = Change of system’s energy

10. First Law – Energy Balance Energy Balance – General system Q in – Q out + W in – W out + E mass,in - E mass,out =  U+  KE  +  PE, kJ q in – q out +  in –  out +  in –  out =  u+  ke  +  pe, kJ/kg

11. First Law – Stationary Closed Energy Balance – Stationary Closed system Q in – Q out + W in – W out + 0 – 0 =  U+  + , kJ q in – q out +  in –  out +  –  =  u+  + , kJ/kg

12. Mass Balance m in – m out =  m sys, kg or First Law – Mass Balance Mass Entering a system - Mass Leaving a system = Change of system’s mass

13. First Law - Mass flow rates Mass Balance – Mass & Volume Flow Rate The volume of the cylinder is The volume flow rate is The velocity of the mass is Then, mass flow rate is

14. First Law – Steady - flow Energy Balance – Control Volume Steady-Flow Steady-flow is a flow where remains constant with time all properties within boundary of the system

15. First Law – single stream CV How to relate changes to the cause Single Stream CV System E 1, P 1, T 1, V 1 To Properties will change indicating change of state Mass in, State 1 Mass out, State 2 E 1, P 1, T 1, V 1

16.  E sys = 0, kJ;  e sys = 0, kJ/kg,  V sys = 0, m 3 ;  m sys = 0 First Law – Steady - flow Energy Balance – Control Volume Steady-Flow Steady-flowall properties remains constant with time Steady-flow is a flow where all properties within boundary of the system remains constant with time

17. First Law – Energy Balance CV Mass & Energy Balance–Steady- Flow CV Energy balance Mass balance

18. First Law – Energy balance CV Mass & Energy Balance–Steady-Flow: Single Stream q in – q out +  in –  out =  out –  in, kJ/kg Energy balance Mass balance IN, 1OUT, 2

19. First Law - Single Stream Mass & Energy Balance–Steady-Flow: Single Stream Energy balance Mass balance

20. First Law Energy balance CV Mass & Energy Balance–Steady-Flow: Single Stream q in – q out +  in –  out =  out –  in, kJ/kg Energy balance: Mass balance: = h 2 – h 1 + ke 2 – ke 1 + pe 2 – pe 1, kJ/kg = h h +  ke +  pe, kJ/kg

21. First Law – Energy Balance CV Mass & Energy Balance–Steady-Flow: Single Stream Energy balance: =  h +  ke +  pe, kJ/kgq in – q out +  in –  out where and

22. First Law of – Ideal Gas Mass & Energy Balance–Steady-Flow CV: Ideal Gases Ideal Gas Equation of State Use Ideal Gas Equation of State for real gases that behave like ideal gases. Criteria: Where is the specific volume,m 3 /kg, R is gas constant, kJ/kg  K, T is absolute temperature in Kelvin For known P and T, use to determine  and hence the mass flow rate. P = RT P gas > T crit. P = RT

23. First Law of – Ideal Gas Mass & Energy Balance–Steady-Flow CV: Ideal Gases of property table Use of property table for real gases that behave like ideal gases. Knowing T, read value for h and vice- versa. If T or h not found, do interpolation

24. First Law - Nozzles Nozzles Energy balance Mass balance Purpose: Increase velocity Effect: Pressure drops In State 1 Out State 2 A 2 << A 1

25. First Law - Nozzles Nozzles Energy balance: Purpose: Increase velocity Effect: Pressure drops Mass balance:

26. First Law - Nozzles Nozzles Energy balance: Purpose: Increase velocity Effect: Pressure drops Air:Use Air:Use energy balance to find h2 h2 h2 h2 and use table A- 17 (& interpolation technique) to determine T2.T2.T2.T2. Air: Use table A-17 to find h 1 (& interpolation technique) for a given T 1. In State 1 Out State 2 A 2 << A 1

27. First Law - Diffusers Diffusers Energy balance: Purpose: Increase Pressure Effect: Velocity drops Air:Use Air:Use energy balance to find h2 h2 h2 h2 and use table A- 17 (& interpolation technique) to determine T2.T2.T2.T2. Air: Use table A-17 to find h 1 (& interpolation technique) for a given T 1. In State 1 Out State 2 A 2 >> A 1

28. First Law - Turbines Turbines Energy balance: Purpose: Purpose: Produce Work Mass balance: = h2 h2 – h 1 + ke 2 – ke 1 + pe 2 – pe 1 q in – q out +  in -  out Effect: Effect: Pressure Drops = h 2 – h 1, kJ/kg –  out In Out = h 1 – h 2, kJ/kg  out

29. First Law - Compressors Energy balance: Mass balance: Compressors Purpose: Purpose: Increase Pressure Sacrifice: Sacrifice: Work supplied = h 2 – h 1, kJ/kg  in Out In = h2 h2 – h 1 + ke 2 – ke 1 + pe 2 – pe 1 q in – q out +  in -  out

30. First Law – Increase Pressure Pressure Increasing Devices Compressors: Compressors: Increase Pressure of gas to high P Sacrifice: Sacrifice: Work supplied Fans: Fans: Increase Pressure of gas slightly slightly to move air Pumps: Pumps: Increase Pressure of liquid to high P

31. First Law - Throttle Throttle

32. First Law - Throttle Energy balance: Mass balance: Throttle Purpose: Purpose: Reduce Pressure Effect: Effect: Temp drops isenthalpic process = h2 h2 – h 1 + ke 2 – ke 1 + pe 2 – pe 1 q in – q out +  in -  out InOut

33. First Law – Mixing Chamber Energy balance: Mass balance: = 3 3 –  1 -  2, kJ/kg q net,in –  net,out Mixing Chamber Purpose: Purpose: Mixing 1 3 2 Then,

34. First Law – Heat Exchanger Heat Exchanger Boundary has 2 inlets and 2 exits

35. First Law – Heat Exchanger Heat Exchanger Boundary has 1 inlet and 1 exit

36. First Law of Thermodynamics Heat Exchanger -no mixing -1 inlet and 1 exit In, 1Exit, 2 In, 3 Exit, 4

37. First Law of Thermodynamics Heat Exchanger -no mixing -2 inlets and 2 exits In, 1Exit, 2 In, 3 Exit, 4

38. First Law of Thermodynamics Heat Exchanger Case 1

39. First Law of Thermodynamics Heat Exchanger Case 2 Q out

40. First Law of Thermodynamics Energy balance: Case 1 Mass balance: Heat Exchanger Purpose: Purpose: Remove or add heat where

41. First Law of Thermodynamics Energy balance: Case 2 Mass balance: Heat Exchanger Purpose: Remove or add heat where Q out

42. First Law of Thermodynamics Energy balance: Case 2 Mass balance: Heat Exchanger Purpose: Remove or add heat where Q in

43. First Law of Thermodynamics “The illiterate of the 21st century will not be those who cannot read and write, but those who cannot learn, unlearn, and relearn.” Author: Alvin Toffler Source: Lessons from the Art of Juggling; How to Achieve Your Full Potential in Business, Learning and Life by Michael Gelb and Tony Buzan Concluding remarks - Quotes