Wet Steam Entropy

Wet steam entropy, abbreviated as \( s_t \), refers to the entropy of a mixture of steam and liquid water.  Entropy is a thermodynamic property that describes the degree of disorder or randomness in a system.  In the context of wet steam, entropy is used to quantify the amount of mixing and randomness between the vapor and liquid phases.  Wet steam occurs when steam contains a certain proportion of liquid water droplets or moisture.  The presence of liquid water in the steam affects its thermodynamic properties, including entropy.

The entropy of wet steam can be calculated using the specific entropy values of the vapor and liquid phases and considering their respective proportions in the mixture.  The specific entropy of the vapor phase and the specific entropy of the liquid phase can be obtained from steam tables or thermodynamic property data.  The calculation of wet steam entropy is more complex than dealing with dry or saturated steam, as it involves accounting for the characteristics of both the vapor and liquid phases.  The entropy of wet steam is typically higher than that of dry steam or superheated steam due to the increased disorder caused by the mixing of two phases.

Entropy plays a fundamental role in thermodynamics and engineering, as it provides insights into energy conversion, heat transfer, and system behavior.  Understanding the entropy of wet steam is important in various applications, including power generation, heat exchangers, and steam turbine efficiency analysis.  It's important to note that the entropy of wet steam can change with variations in pressure, temperature, and the proportion of liquid water.  Therefore, it is necessary to consider the specific conditions and properties of the wet steam mixture when calculating its entropy.

 

Wet Steam Entropy formula
\( s_t = s_s \; \zeta + \left( 1 - \zeta  \right) \; s_w \)
Symbol	English	Metric
\( s_t \) = wet steam entropy	\(Btu\;/\;lbm-R\)	\(kJ\;/\;kg-K\)
\( s_s \) = dry steam entropy	\(Btu\;/\;lbm-R\)	\(kJ\;/\;kg-K\)
\( \zeta \)  (Greek symbol zeta) = wet steam dryness fraction	\( dimensionless \)
\( s_w \) = entropy of saturated water of concensate	\(Btu\;/\;lbm-R\)	\(kJ\;/\;kg-K\)