How to Calculate and Solve for Entropy of Evapourisation (Wet Steam) | Enthalpy

June 28, 2022 Loveth Idoko

Last Updated on May 23, 2024

The entropy of evapourisation (wet steam) is illustrated by the image below. To calculate entropy of evapourisation (wet steam), three essential parameters are needed and these parameters are Enthalpy of Evapourisation (h_fg), Saturated Temprature (T_s) and Dryness Fraction (x).

The formula for calculating entropy of evapourisation (wet steam):

S_evap = ^xh_fg / _Ts

Where:

S_evap = Entropy of Evapourisation (Wet Steam)
h_fg = Enthalpy of Evapourisation
T_s = Saturated Temprature
x = Dryness Fraction

Given an example;
Find the entropy of evapourisation when the enthalpy of evapourisation is 10, the saturated temperature is 5 and the dryness fraction is 2.

This implies that;

h_fg = Enthalpy of Evapourisation = 10
T_s = Saturated Temprature = 5
x = Dryness Fraction = 2

S_evap = ^xh_fg / _Ts
That is, S_evap = ^{2 x 10} / ₅
S_evap = ²⁰ / ₅
S_evap = 4

Therefore, the entropy of evapourisation is 4 J/K.

Calculating the Enthalpy of Evapourisation when the Entropy of Evapourisation, the Saturated Temperature, the Dryness Fraction are Given

hfg = ^{S_evap x T_s} / _x

Where:

h_fg = Enthalpy of Evapourisation
S_evap = Entropy of Evapourisation (Wet Steam)
T_s = Saturated Temprature
x = Dryness Fraction

Let’s solve an example;
Find the enthalpy of evapourisation when the entropy of evapourisation is 10, the saturated temperature is 6 and the dryness fraction is 2.

This implies that;

S_evap = Entropy of Evapourisation (Wet Steam) = 10
T_s = Saturated Temprature = 6
x = Dryness Fraction = 2

hfg = ^{S_evap x T_s} / _x
That is, hfg = ^{10 x 6} / ₂
hfg = ⁶⁰ / ₂
hfg = 30

Therefore, the enthalpy of evapourisation is 30.

Calculating the Saturated Temperature when the Entropy of Evapourisation, the Enthalpy of Evapourisation and the Dryness Fraction are Given

T_s = ^xh_fg / _{S_evap}

Where:

T_s = Saturated Temprature
S_evap = Entropy of Evapourisation (Wet Steam)
h_fg = Enthalpy of Evapourisation
x = Dryness Fraction

Let’s solve an example;
Find the saturated temperature when the entropy of evapourisation is 12, the enthalpy of evapourisation is 8 and the dryness fraction is 3.

This implies that;

S_evap = Entropy of Evapourisation (Wet Steam) = 12
h_fg = Enthalpy of Evapourisation = 8
x = Dryness Fraction = 3

T_s = ^xh_fg / _{S_evap}
So, T_s = ⁽³⁾⁽⁸⁾ / ₁₂
T_s = ²⁴ / ₁₂
T_s = 2

Therefore, the saturated temperature is 2.

Calculating the Dryness Fraction when the Entropy of Evapourisation, the Enthalpy of Evapourisation and the Saturated Temperature are Given

x = ^{S_evap x T_s} / _{h_fg}

Where:

x = Dryness Fraction
S_evap = Entropy of Evapourisation (Wet Steam)
h_fg = Enthalpy of Evapourisation
T_s = Saturated Temprature

Let’s solve an example;
Find the dryness fraction when the entropy of evapourisation is 14, the enthalpy of evapourisation is 6 and the saturated temperature is 4.

This implies that;

S_evap = Entropy of Evapourisation (Wet Steam) = 14
h_fg = Enthalpy of Evapourisation = 6
T_s = Saturated Temprature = 4

x = ^{S_evap x T_s} / _{h_fg}
Then, x = ^{14 x 4} / ₆
x = ⁵⁶ / ₆
x = 9.33

Therefore, the dryness fraction is 9.33.

How to Calculate Entropy of Evapourisation (Wet Steam) Using Nickzom Calculator

Nickzom Calculator – The Calculator Encyclopedia is capable of calculating the entropy of evapourisation.

To get the answer and workings of the entropy of evapourisation using the Nickzom Calculator – The Calculator Encyclopedia. First, you need to obtain the app.

You can get this app via any of these means:

Web – https://www.nickzom.org/calculator-plus

To get access to the professional version via web, you need to register and subscribe to have utter access to all functionalities.
You can also try the demo version via https://www.nickzom.org/calculator

Android (Paid) – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator
Android (Free) – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

Apple (Paid) – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8
Once, you have obtained the calculator encyclopedia app, proceed to the Calculator Map, then click on Materials and Metallurgical under Engineering.

Now, Click on Chemical Reaction Thermodynamics under Materials and Metallurgical

So, Click on Enthalpy under Chemical Reaction Thermodynamics

Now, Click on Entropy of Evapourisation under Enthalpy

The screenshot below displays the page or activity to enter your values, to get the answer for the entropy of evapourisation according to the respective parameter which is the Enthalpy of Evapourisation (h_fg), Saturated Temprature (T_s) and Dryness Fraction (x).

Now, enter the values appropriately and accordingly for the parameters as required by the Enthalpy of Evapourisation (h_fg) is 10, Saturated Temprature (T_s) is 5 and Dryness Fraction (x) is 2.

Finally, Click on Calculate

As you can see from the screenshot above, Nickzom Calculator– The Calculator Encyclopedia can calculate the entropy of evapourisation (wet steam) and presents the formula, workings and steps too.