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 - hs - from the steam tables. Wet steam has less usable heat energy than dry saturated steam.
ht = hs ζ + (1 - ζ) hw (1)
where
ht= enthalpy of wet steam (kJ/kg, Btu/lb)
hs= enthalpy of steam (kJ/kg, Btu/lb)
ζ = dryness fraction
hw= enthalpy of saturated water or condensate (kJ/kg, Btu/lb)
The dryness fraction can be expressed as
ζ = ws / (ww + ws) (2)
where
ζ = dryness fraction
ww = mass of water (kg, lb)
ws = mass of steam (kg, lb)
