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# How to Calculate and Solve for Internal Energy of Steam (wet steam) | Enthalpy

Last Updated on June 6, 2022

The internal energy of steam(wet steam) is illustrated by the image below.

To compute for internal energy of steam, five essential parameters are needed and these parameters are Enthalpy of Wet Steam (h), Specific Volume of Gas (vg), Pressure (P), Dryness Fraction (x) and J.

The formula for calculating the internal energy of steam(wet steam):

U = h – Pxvg / J

Where:

U = Internal Energy of Steam(wet Steam)
h = Enthalpy of Wet Steam
vg = Specific Volume of Gas
x = Dryness Fraction
P = Pressure

Given an example;
Find the internal energy of steam (wet steam) when the enthalpy of wet steam is 16, the specific volume of gas is 13, the dryness fraction is 10 and the pressure is 6.

This implies that;

h = Enthalpy of Wet Steam = 16
vg = Specific Volume of Gas = 13
x = Dryness Fraction = 10
P = Pressure = 6

U = h – Pxvg / J
U = 16 – 10 x 6 x 13 / 1
U = 16 – 780 / 1
U = 16 – 780
U = -764

Therefore, the internal energy of steam (wet steam) is -764 J.

Calculating the Enthalpy of Wet Steam when the Internal Energy of Steam, the Specific Volume of Gas, the Dryness Fraction and the Pressure is Given.

h = U + Pxvg / J

Where:

h = Enthalpy of Wet Steam
U = Internal Energy of Steam(wet Steam)
vg = Specific Volume of Gas
x = Dryness Fraction
P = Pressure

Let’s solve an example;
Find the enthalpy of wet steam when the internal energy of steam is 14, the specific volume of gas is 2, the dryness fraction is 6 and the pressure is 3.

This implies that;

U = Internal Energy of Steam(wet Steam) = 14
vg = Specific Volume of Gas = 2
x = Dryness Fraction = 6
P = Pressure = 3

h = U + Pxvg / J
h = 14 + 3(6)(2) / 1
h = 14 + 36 / 1
h = 14 + 36
h = 50

Therefore, the enthalpy of wet steam is 50.

Calculating the Specific Volume of Gas when the Internal Energy of Steam, the Enthalpy of Wet Steam, the Dryness Fraction and the Pressure is Given.

vg = h – U / Px x J

Where:

vg = Specific Volume of Gas
U = Internal Energy of Steam(wet Steam)
h = Enthalpy of Wet Steam
x = Dryness Fraction
P = Pressure

Let’s solve an example;
Find the specific volume of gas when the internal energy of steam is 9, the enthalpy of wet steam is 18, the dryness fraction is 7 and the pressure is 2.

This implies that;

U = Internal Energy of Steam(wet Steam) = 9
h = Enthalpy of Wet Steam = 18
x = Dryness Fraction = 7
P = Pressure = 2

vg = h – U / Px x J
vg = 18 – 9 / 7(2) x 1
vg = 9 / 14 x 1
vg = 0.64 x 1
vg = 0.64

Therefore, the specific volume of gas is 0.64.

Calculating the Dryness Fraction when the Internal Energy of Steam, the Enthalpy of Wet Steam, the Specific Volume of Gas and the Pressure is Given.

x = h – U / Pvg x J

Where:

x = Dryness Fraction
U = Internal Energy of Steam(wet Steam)
h = Enthalpy of Wet Steam
vg = Specific Volume of Gas
P = Pressure

Let’s solve an example;
Find the dryness fraction when the internal energy of steam is 6, the enthalpy of wet steam is 24, the specific volume of gas is 4 and the pressure is 2.

This implies that;

U = Internal Energy of Steam(wet Steam) = 6
h = Enthalpy of Wet Steam = 24
vg = Specific Volume of Gas = 4
P = Pressure = 2

x = h – U / Pvg x J
x = 24 – 6 / 2(4) x 1
x = 18 / 8 x 1
x = 2.25 x 1
x = 2.25

Therefore, the dryness fraction is 2.25.

Calculating the Pressure when the Internal Energy of Steam, the Enthalpy of Wet Steam, the Specific Volume of Gas and the Dryness Fraction is Given.

P = h – U / xvg x J

Where:

P = Pressure
U = Internal Energy of Steam(wet Steam)
h = Enthalpy of Wet Steam
vg = Specific Volume of Gas
x = Dryness Fraction

Let’s solve an example;
Find the pressure when the internal energy of steam is 10, the enthalpy of wet steam is 32, the specific volume of gas is 5 and the dryness fraction is 6.

This implies that;

U = Internal Energy of Steam(wet Steam) = 10
h = Enthalpy of Wet Steam = 32
vg = Specific Volume of Gas = 5
x = Dryness Fraction = 6

P = h – U / xvg x J
P = 32 – 10 / 6(5) x 1
P = 22 / 30 x 1
P = 0.73 x 1
P = 0.73

Therefore, the pressure is 0.73.

Nickzom Calculator – The Calculator Encyclopedia is capable of calculating the internal energy of steam (wet steam).

To get the answer and workings of the internal energy of steam (wet steam) using the Nickzom Calculator – The Calculator Encyclopedia. First, you need to obtain the app.

You can get this app via any of these means:

You can also try the demo version via https://www.nickzom.org/calculator

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

Now, Click on Enthalpy under Chemical Reaction Thermodynamics

Now, Click on Internal Energy of Steam (wet steam) under Enthalpy

The screenshot below displays the page or activity to enter your values, to get the answer for the internal energy of steam according to the respective parameter which is the Enthalpy of Wet Steam (h), Specific Volume of Gas (vg), Pressure (P), Dryness Fraction (x) and J.

Now, enter the values appropriately and accordingly for the parameters as required by the Enthalpy of Wet Steam (h) is 16, Specific Volume of Gas (vg) is 13, Pressure (P) is 10, Dryness Fraction (x) is 6 and J is 1.

Finally, Click on Calculate

As you can see from the screenshot above, Nickzom Calculator– The Calculator Encyclopedia solves for the internal energy of steam and presents the formula, workings and steps too.