1. + FE Thermodynamics Review Dr. Omar Meza Assistant Professor Department of Mechanical Engineering

2. + Topics covered  Thermodynamics Law  1 st and 2 nd law  Energy, heat and work  Availability and reversibility  Cycles  Ideal gases  Mixture of gases  Phase change  Heat Transfer  Properties of:  enthalpy  entropy

3. + Tips for taking exam  Use the reference handbook  Know what it contains  Know what types of problems you can use it for  Know how to use it to solve problems  Refer to it frequently  Work backwards when possible  FE exam is multiple choice with single correct answer  Plug answers into problem when it is convenient to do so  Try to work backwards to confirm your solution as often as possible  Progress from easiest to hardest problem  Same number of points per problem  Calculator tips  Check the NCEES website to confirm your model is allowed  Avoid using it to save time!  Many answers do not require a calculator (fractions vs. decimals)

4. + Properties of Single-Component Systems Handbook page: For a simple substance, specification of any two intensive, independent properties is sufficient to fix all the rest.

5. + Properties of Single-Component Systems Handbook page: A substance that has a fixed chemical composition throughout is called a pure substance.

6. + Properties of Single-Component Systems A substance whose properties are uniform throughout is referred to as A. A solid B. An ideal substance C. A pure substance D. A standard substance A substance whose properties are uniform throughout is referred to as A. A solid B. An ideal substance C. A pure substance D. A standard substance

7. + Properties of Single-Component Systems

8. + Given: Steam at 2.0 kPa is saturated at 17.5 o C. In what state will the steam be at 40 o C if the pressure is 2.0 kPa? Given: Steam at 2.0 kPa is saturated at 17.5 o C. In what state will the steam be at 40 o C if the pressure is 2.0 kPa? Analysis: Analysis: @ P = 2.0 kPa, T sat = 17.5 o C @ P = 2.0 kPa, T sat = 17.5 o C T sat < T  “superheated vapor” T sat < T  “superheated vapor” Tsat= 17.5 o C T= 40 o C

9. + Properties of Single-Component Systems

10. + Find the volume occupied by 20 kg of steam at 0.4 MPa, 400 o C Find the volume occupied by 20 kg of steam at 0.4 MPa, 400 o C At 0.4 MPa the T sat =142 o C approximately. It means that the steam is in the superheated region At 0.4 MPa the T sat =142 o C approximately. It means that the steam is in the superheated region

11. + Properties of Single-Component Systems Handbook page: Real gases exhibit ideal- gas behavior at relatively low pressures and high temperatures.

12. + Properties of Single-Component Systems All real gases deviate somewhat from ideal gas behavior: PV= mRT. For which of the following conditions is the deviation the smallest? A. High temperature and low volume B. High temperature and low pressures C. High pressures and low volumes D. High pressure and low temperatures When the volume of an ideal gas is doubled while the temperature is halved, what happens to the pressure? A.Pressure is doubled B.Pressure is halved C.Pressure is quartered D.Pressure is quadrupled

13. + Properties of Single-Component Systems Handbook page:

14. + Properties of Single-Component Systems

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16. + First Law of Thermodynamics Handbook page:

17. + First Law of Thermodynamics Handbook page: Formal sign convention: Heat transfer to a system and work done by a system are positive; heat transfer from a system and work done on a system are negative. W b is positive  for expansion W b is negative  for compression

18. + First Law of Thermodynamics

19. + During a process, 30J of work are done by a closed stationary system on its surroundings. The internal energy of the system decreases by 40 j. What is the heat transfer?

20. + First Law of Thermodynamics Handbook page:

21. + First Law of Thermodynamics Calculate the work done by a piston contained within a cylinder with air if 2m 3 is tripled while the temperature is maintained at a constant T = 30 o C. The initial pressure is P 1 =400 kPa absolute.

22. + First Law of Thermodynamics Polytropic process in a closed system

23. + First Law of Thermodynamics Handbook page:

24. + First Law of Thermodynamics Handbook page:

25. + First Law of Thermodynamics

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28. + First Law of Thermodynamics Handbook page:

29. + First Law of Thermodynamics Handbook page:

30. + First Law of Thermodynamics A steam coil operating at steady state receives 30 kg/min of steam with an enthalpy of 2900 kJ/kg. if the steam leaves with an enthalpy of 1600 kJ/min, what is the rate of heat transfer from the coil?

31. + First Law of Thermodynamics

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33. + Basic Cycles

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37. + Basic Cycles

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54. + Ideal Gas Mixture Handbook page:

55. + Ideal Gas Mixture

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58. + Psychrometrics Handbook page:

59. + Psychrometrics Mollier Diagram

60. + Psychrometrics

61. + Psychrometrics

62. + Psychrometrics

63. + Psychrometrics

64. + Psychrometrics

65. + Psychrometrics

66. + Psychrometrics

67. + Psychrometrics

68. + Psychrometrics

69. + Combustion Processes

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74. + Second Law of Thermodynamics Handbook page:

75. + Second Law of Thermodynamics Part of the heat received by a heat engine is converted to work, while the rest is rejected to a sink. This is a law. 1.It is always observed in real heat engines. 2.One cannot derive it from first principles. 3.No exceptions are known. It is not just that we haven’t looked hard enough and that future discoveries will make it possible to convert heat completely to work.

76. + Second Law of Thermodynamics

77. + The efficiency of a refrigerator is expressed in terms of the coefficient of performance (COP). The objective of a refrigerator is to remove heat (Q L ) from the refrigerated space. Can the value of COP R be greater than unity?

78. + Second Law of Thermodynamics The work supplied to a heat pump is used to extract energy from the cold outdoors and carry it into the warm indoors. for fixed values of Q L and Q H

79. + Second Law of Thermodynamics A)1500-MW B)600-MW C)900-MW D)2100-MW

80. + Second Law of Thermodynamics A)Yes B)No C)Not clear D)NA

81. + Entropy

82. + Entropy A)2.82 kJ/K B)6.86 kJ/K C)-8.10 kJ/K D)8.10 kJ/K

83. + Preguntas? Comentarios?

84. + Muchas Gracias !