Specific Enthalpy of Vaporization Formula |
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\( h_{fg} \;=\; h_g - h_f \) (Specific Enthalpy of Vaporization) \( h_g \;=\; h_{fg} + h_f \) \( h_f \;=\; h_g - h_{fg} \) |
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| Symbol | English | Metric |
| \( h_{fg} \) = Specific Enthalpy of Vaporization | \(Btu\;/\;lbm\) | \(kJ\;/\;kg\) |
| \( h_g \) = Specific Enthalpy of Saturated Vapor | \(Btu\;/\;lbm\) | \(kJ\;/\;kg\) |
| \( h_f \) = Specific Enthalpy of Saturated Liquid | \(Btu\;/\;lbm\) | \(kJ\;/\;kg\) |
Specific enthalpy of vaporization, abbreviated as \( h_{fg} \), is the amount of energy required to convert a unit mass of a liquid into vapor at a constant pressure and temperature, without changing its temperature. It represents the heat input needed to overcome the intermolecular forces that hold the liquid molecules together, allowing them to escape into the vapor phase.
The specific enthalpy of vaporization is used in processes such as boiling, evaporation, and condensation, and it decreases as the temperature approaches the critical point, eventually becoming zero at the critical temperature where the liquid and vapor phases become indistinguishable.
