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 (v**_{g}), 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

v_{g} = 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

v_{g} = 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)

v_{g} = 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

v_{g} = 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.**

v_{g} = ^{h – U} / _{Px} x J

Where:

v_{g} = 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

v_{g} = ^{h – U} / _{Px} x J

v_{g} = ^{18 – 9} / _{7(2)} x 1

v_{g} = ^{9} / _{14} x 1

v_{g} = 0.64 x 1

v_{g} = 0.64

Therefore, the **specific volume of gas **is **0.64.**

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