What is hfg enthalpy?
hfg represents enthalpy diference beetween gas and fluid and it tells how much heat is needed to change 1kg of boiling water to steam we call it specific heat of evaporation (you may also find r0). hf is enthalpy of given substance at saturated liquid state and hg is enthalpy of substance at saturated vapour state for given saturated state. H = U + PV H = m * Cp * dT dH = dU + pdV + VdP h = hf + (x)hfg hfg = hg - hf where: H = enthalpy. Introduction and definition of vapor and steam enthalpy - specific enthalpy of saturated liquid, saturated vapor and superheated vapor. total enthalpy = hf + (dryness fraction) x (hfg).