Chapters 2 & 3 Energy Balances
Work done by the system, W = -‐ Force applied to the system, F Δx
or
W = − F x ∫ ( ) dx
W
EC= − PAdx ∫ = − PdV ∫
Expansion/Contrac8on of a Closed System
Sha= Work for an Open System
W
S= − V dP
in
out
∫
Pump leads to a change in pressure at constant volumeForce leads to a change in volume at constant pressure
1
Work Associated with Flow
W Flow = PV ( )
inm
in− PV ( )
outm
outLost Work
Viscosity Gradient (Pressure Gradients) Temperature Gradient
ConcentraEon Gradient
FricEon (of a piston for instance)
Reversible Process
Viscosity Gradient (Pressure Gradients) Temperature Gradient
ConcentraEon Gradient
FricEon (of a piston for instance)
2
3
Work is a path funcEon not a state funcEon
4
5
6
7
8
9
Steady-‐State Open System
10
11
12
Open System
13
14
15
General Equa8on for Open System
16
17
18
19
20
21
22
23
24
25
26
27
28
Cocurrent
Countercurrent Superheater
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
10,12,14,15,16,17
44
45
2.2, 2.4
46
2.6
47
7,8,12,13,15
48
16,17,18,21,22
49
23