Average Quiz 4 65

(1)

1

Average Quiz 4 65

(2)

2

(3)

3

(4)

4

For a single state ln(1) = 0. At absolute 0, in a perfect crystal with no defects etc.

Entropy of different aspects of a system, conformational entropy, translational entropy A contribution to energy that is linear in temperature

(5)

5

(6)

6

(7)

7

Statistical Thermodynamics (Mechanics)

(8)

8

(9)

9

(10)

10

(11)

11

(12)

12

(13)

13

(14)

14

Allows Calculation of Effeciency

S=0 process has no waste energy (heat) Actually process has waste energy

Ratio of Wwith waste/S=0 work = effeciency Defines “reversible” as DS = 0

Defines “impossible” as self-organizing;

DS < 0 with no energy input

(15)

15

(16)

16

(17)

17

(18)

18

Water

(19)

19

Water

(20)

20

Water

(21)

21

(22)

22

Rules for Carnot Cycle Isothermal

(vary P) Q = -W^EC = -nRTln(V²/ V¹) Isothermal

Isobaric Q = DU - W^EC = DU + PDV = DH W^EC = -PDV

Adiabatic

Reversible Q = 0 DS = 0

W^EC = DU = R C^V (T² – T¹) For Turbine

The work done by the gas is work done by the turbine (blades moved around by the gas) plus the work done by pressures (flow work).

U² – U¹ = -W^shaft + P¹V¹ – P²V² (adiabatic turbine) -W^shaft = H² – H¹

Difference between shaft work and expansion/contraction work

(23)

23

(24)

24

(25)

25

(26)

26

(27)

27

(28)

28

(29)

29

(30)

30

(31)

31

(32)

32

(33)

33

(34)

34

(35)

35

(36)

36

(37)

37

(38)

38

(39)

39

(40)

40

(41)

41

(42)

42

(43)

43

(44)

44

(45)

45

(46)

46

Summary of Process and General Rules Nozzle DS = 0

DH=D(1/2 mv²)

Throttle DS = -Rln(P²/P¹) (i.g.) DH=1/2 mv²

Generally DH=0

Pump DS = 0 for adiabatic reversible DH=W^S=DH’/h^eff

Turbine DS = 0 for adiabatic reversible DH=W^S=DH’h^eff

Isothermal (DS)^T = R ln[V²/V¹] i.g.

= -R ln[P²/P¹] (DH)^T=0

Ideal Mixing DS^mix = -R Sxⁱ lnxⁱ Adiabatic, Reversible

DS = 0

Isobaric (dS)^P = C^p (dT)^P/T (dS/dT)^P = C^p/T Constant Volume

(dS)^V = C^V (dT)^V/T (dS/dT)^V = C^V/T

Phase Change DS^trans = DH^trans/T^trans Carnot (Use °K)

Engine h^eff = (T^H- T^C)/T^H Refrigerator COP = T^C/(T^H- T^C) Heat Pump COP = T^H/(T^H- T^C)

(47)

47

(48)

48

(49)

49

(50)

50

(51)

51

Water

(52)

52

Water

(53)

53

Water

(54)

54

(55)

55

(56)

56

(57)

57

(58)

58

(59)

59

(60)

60

(61)

61

(62)

62

(63)

63

(64)

64

(65)

65

(66)

66

(67)

67

(68)

68

(69)

69

(70)

70

(71)

71

(72)

72