Dry steam is steam that contains no liquid water droplets. The enthalpy of dry steam is the total heat energy contained within one unit of mass of this dry steam at a specific pressure and temperature. This total heat energy is composed of two parts: the sensible heat required to raise the water to its boiling point at that pressure, and the latent heat of vaporization needed to convert the boiling water entirely into steam. Therefore, the dry steam enthalpy represents the maximum energy that can be extracted from saturated steam at a given condition through condensation. Engineers and scientists often refer to steam tables to find the specific enthalpy values of dry steam at various pressures and temperatures, which are crucial for designing and analyzing thermodynamic systems that utilize steam for power generation, heating, or other industrial processes.
There isn't a single, simple algebraic formula to directly calculate the enthalpy of dry steam. Instead, the enthalpy of dry steam at a specific pressure and temperature is typically obtained from steam tables or thermodynamic property software. You need to know either the pressure or the temperature of the dry steam. Since dry steam is saturated vapor, knowing one of these properties fixes the other. Steam tables are organized lists that provide thermodynamic properties of water and steam at various saturation temperatures and pressures. You would look up the given pressure (or temperature) in the table. Corresponding to the given pressure (or temperature), the steam table will list the specific enthalpy of the saturated vapor phase. This value represents the enthalpy of dry steam at that condition.
