Wet Steam  Enthalpy
Wet steam, dryness fraction and enthalpy.
The actual enthalpy of evaporated wet steam is the product of the dryness fraction  ζ  and the specific enthalpy  h_{s}  from the steam tables. Wet steam has less usable heat energy than dry saturated steam.
h_{t} = h_{s} ζ + (1  ζ) h_{w} (1)
where
h_{t} = enthalpy of wet steam (kJ/kg, Btu/lb)
h_{s} = enthalpy of steam (kJ/kg, Btu/lb)
ζ = dryness fraction
h_{w} = enthalpy of saturated water or condensate (kJ/kg, Btu/lb)
The dryness fraction can be expressed as
ζ = w_{s} / (w_{w} + w_{s}) (2)
where
ζ = dryness fraction
w_{w} = mass of water (kg, lb)
w_{s} = mass of steam (kg, lb)
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