Enthalpy Wet Steam

Overview

Engineering reference data for Enthalpy Wet Steam in thermodynamics.

Key Formulas

First Law

$\Delta U = Q - W$

Energy is conserved — heat added minus work done.

Ideal Gas Law

$PV = nRT$

Relates pressure, volume, and temperature of an ideal gas.

Heat Transfer

$Q = mc\Delta T$

Sensible heat transfer.

Carnot Efficiency

$\eta = 1 - T_C/T_H$

Maximum efficiency between two temperatures.

Variables

Symbol	Description	Unit
$U$	Internal energy	J
$Q$	Heat	J
$W$	Work	J
$P$	Pressure	Pa
$V$	Volume	m³
$T$	Temperature	K

Example: Wet Steam Enthalpy Calculation

Consider a practical scenario to illustrate the calculation of wet steam enthalpy. Suppose wet steam has a dryness fraction ($\zeta$) of 0.8. From steam tables at the relevant pressure, the specific enthalpy of steam ($h_s$) is 2778 kJ/kg, and the enthalpy of saturated water ($h_w$) is 504 kJ/kg.

The enthalpy of wet steam ($h_t$) is calculated using:

$h_t = h_s \cdot \zeta + (1 - \zeta) \cdot h_w$

Substituting the values:

$h_t = 2778 \times 0.8 + (1 - 0.8) \times 504$

$h_t = 2222.4 + 100.8 = 2323.2 \text{ kJ/kg}$

This result shows that wet steam with a dryness fraction of 0.8 has an enthalpy of 2323.2 kJ/kg, which is less than the enthalpy of dry saturated steam at the same pressure. Accurate determination of the dryness fraction is critical for efficient energy utilization in steam systems.

References

• Original Source