Specific Enthalpy of Saturated Water

 The specific enthalpy of saturated water refers to the total energy content per unit mass of water at the saturation point, where it exists as both liquid and vapor phases in equilibrium. This value represents the enthalpy of water in its liquid state at the boiling point, just before it starts to vaporize into steam.

The specific enthalpy of saturated water depends on its pressure. At standard atmospheric pressure (101.3 kPa or 1 atm), the specific enthalpy of saturated water is approximately 419 kJ/kg or 180 BTU/lb.

However, at different pressures, the specific enthalpy of saturated water will vary. For example, at higher pressures, such as those encountered in industrial boilers, the specific enthalpy of saturated water will be higher due to the increased energy required to maintain it in the liquid state.

Engineers and designers often refer to steam tables or use steam property calculators to find the specific enthalpy values of saturated water at various pressures relevant to their applications. These values are crucial for designing and operating steam-based systems efficiently and safely.

The specific enthalpy ($ℎ$) of water can be calculated using the equation:

$ℎ={𝑐}_{𝑝}\cdot (𝑇-{𝑇}_{𝑟𝑒𝑓})$

Where:

• $ℎ$ = specific enthalpy of water (in joules per kilogram, J/kg)
• ${𝑐}_{𝑝}$ = specific heat capacity of water (in joules per kilogram per Kelvin, J/(kg·K))
• $𝑇$ = temperature of the water (in Kelvin, K)
• ${𝑇}_{𝑟𝑒𝑓}$ = reference temperature (in Kelvin, K)

The specific heat capacity of water, ${𝑐}_{𝑝}$, is approximately 4,186 J/(kg·K) at standard conditions.

If you are working in Celsius, you can convert the temperature to Kelvin by adding 273.15:

${𝑇}_{𝐾𝑒𝑙𝑣𝑖𝑛}={𝑇}_{𝐶𝑒𝑙𝑠𝑖𝑢𝑠}+273.15$

Then, you can use this temperature in the equation to calculate the specific enthalpy.

Remember, this equation provides the specific enthalpy of water in its liquid state. If you are interested in the specific enthalpy of water vapor (steam), you would need to account for the phase change and latent heat of vaporization.