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 Dew-Point Pressure – Liquid Below Bubble-Point Temperature or Above Bubble-Point Pressure
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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 Dew-
Point Pressure
– Liquid Below Bubble-Point Temperature or Above Bubble-Point Pressure
Vaporize 1kg Water at 20 C and Bubble Point Pressure
ˆ ˆ
ˆ ˆ
U Q W Q P V
m U Q mP V
Q m U P V
3 5
2
ˆ ˆ
2403.0 83.91
57.8 0.0010021 0.0234 1 10
1,000
2454.3
Q m U P V
kJkgQ
kg
mkg bar N kJ
kg m bar N m
Q kJ
H U PV
H U P V
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.
Vapor
Liquid
Water Vapor Heating1 kg from 100 oC, 1 Bar to 200 oC, 1 Bar
ˆ ˆ
ˆ ˆ ˆ
U Q W Q P V
m U Q mP V
Q m U P V m H
Water Vapor Heating1 kg from 100 oC, 1 Bar to 200 oC, 1 Bar
ˆ ˆ ˆ
2875 26761199
Q m U P V m H
kJkgQ kJ
kg
Constant Volume Water Vapor Heating1 kg from 100 oC, 1 Bar to 200 oC, P=?