The document discusses the use of steam tables to determine properties of water and steam under different conditions. It provides examples of using steam tables to calculate: 1) The heat required to vaporize 1kg of water at 20°C and the bubble point pressure 2) The internal energy change and heat transfer for heating 1kg of steam from 100°C to 200°C at a constant pressure of 1 bar 3) Using interpolation in steam tables to find the pressure and internal energy for constant volume heating of 1kg steam from 100°C to 200°C.

1. Use of Steam Tables
• Saturated Vapor or Liquid
– Liquid at Bubble-Point
– Vapor at Dew-Point
– Liquid and Vapor Co-existing
• Superheated Vapor or Sub-Cooled Liquid
– Vapor Above Dew-Point Temperature or Below DewPoint Pressure
– Liquid Below Bubble-Point Temperature or Above
Bubble-Point Pressure

3. Vaporize 1kg Water at 20 C and Bubble Point Pressure
U
Q W
ˆ
m U
Q
m
Q P V
ˆ
Q mP V
ˆ
U
ˆ
P V

5. ˆ
U
ˆ
P V
Q
m
Q
1kg 2403.0 83.9 kJ
kg
57.8 0.001002 m3 1 105 N
1kg 0.0234 bar
kJ
kg
m 2bar 1, 000 N m
Q
2454.3 kJ
H
U
H
U
PV
P V

9. Definitions
• Degrees of Superheat
– Difference between actual temperature and
saturation temperature at the same pressure
• Degrees of Sub-Cooling
– Difference between actual temperature and the
saturation temperature at the same pressure.

10. Vapor
Liquid

11. Water Vapor Heating
1 kg from 100 oC, 1 Bar to 200 oC, 1 Bar
U
Q W
ˆ
m U
Q
m
Q P V
ˆ
Q mP V
ˆ
U
ˆ
P V
ˆ
m H

13. Water Vapor Heating
1 kg from 100 oC, 1 Bar to 200 oC, 1 Bar
ˆ
U
ˆ
P V
ˆ
m H
Q
m
Q
1kg 2875 2676 kJ
kg
199kJ

14. Constant Volume Water Vapor Heating
1 kg from 100 oC, 1 Bar to 200 oC, P=?
V
U
ˆ
m U
0
Q
Q

15. Ideal Gas Law Estimation
P2
T2
P
1
T1
473.15
1 bar
373.15
1.73 bar

17. Interpolation for Pressure
6
Pressure
5
4
3
2
1
0
0.3
0.5
0.7
0.9
1.1
1.3
1.5
Specific Volume
1.7
1.9
2.1
2.3

18. Interpolation for Internal Energy
Internal Energy
2660
2655
2650
2645
2640
0.3
0.5
0.7
0.9
1.1
1.3
1.5
Specific Volume
1.7
1.9
2.1
2.3

19. Linear Interpolation
y
mx b
y1
mx1 b
y2
y1
m
y2
m x2
y2
x1
y1
x2
mx2 b
x1
b
y1 mx1
y
mx
y
y1 m x x1
y
y1
y1 mx1
y2
y1
x2
x1
x x1

20. P
P
1
P2 P
1
ˆ ˆ
V2 V1
ˆ
ˆ
VDesired V1
5 1
P 1
1.69 2.17
0.425 2.17
ˆ
ˆ
U 2 U1
ˆ ˆ
ˆ
ˆ
U U1
VDesired V1
ˆ ˆ
V2 V1
2.1 bar
ˆ
U
2643 2658
2658
1.69 2.17
0.425 2.17
Q
ˆ
m U
kJ
1 kg 2654 2507
kg
kJ
2654
kg
147 kJ