The entropy of wet steam is illustrated by the image below.
To compute for entropy of wet steam, three essential parameters are needed and these parameters are Entropy of Water (Sf), Enthalpy of Vapourisation (hfg) and Saturated Temprature (Ts).
The formula for calculating entropy of wet steam:
Sg = Sf + hfg / Ts
Where:
Sg = Entropy of Wet Steam
Sf = Entropy of Water
hfg = Enthalpy of Vapourisation
Ts = Saturated Temprature
Given an example;
Find the entropy of wet steam when the entropy of water is 12, the enthalpy of vapourisation is 10 and the saturated temperature is 14.
This implies that;
Sf = Entropy of Water = 12
hfg = Enthalpy of Vapourisation = 10
Ts = Saturated Temprature = 14
Sg = Sf + hfg / Ts
Sg = 12 + 10 / 14
Sg = 12 + 0.714
Sg = 12.71
Therefore, the entropy of wet steam is 12.71 J/K.
Calculating the Entropy of Water when the Entropy of Wet Steam, the Entropy of Vapourization and the Saturated Temperature is Given.
Sf = (Sg x Ts) – hfg
Where:
Sf = Entropy of Water
Sg = Entropy of Wet Steam
hfg = Enthalpy of Vapourisation
Ts = Saturated Temprature
Let’s solve an example;
Find the entropy of water when the entropy of wet steam is 10, the enthalpy of vapourization is 5 and the saturated temperature is 2.
This implies that;
Sg = Entropy of Wet Steam = 10
hfg = Enthalpy of Vapourisation = 5
Ts = Saturated Temprature = 2
Sf = (Sg x Ts) – hfg
Sf = (10 x 2) – 5
Sf = 20 – 5
Sf = 15
Therefore, the entropy of water is 15.
Continue reading How to Calculate and Solve for Entropy of Wet Steam | Enthalpy