How to Calculate and Solve for Energy Transfer by Radiation | Radiation Heat Transfer

The image above represents energy transfer by radiation.

To compute for energy transfer by radiation, three essential parameters are needed and these parameters are Emissivity (ε1), Absorbivity (α1) and Emissive Power of Black Body (eb).

The formula for calculating energy transfer by radiation:

qnet = eb1 – α1)

Where:

qnet = Energy Transfer by Radiation
ε1 = Emissivity
α1 = Absorbivity
eb = Emissive Power of Black Body

Let’s solve an example;
Find the energy transfer by radiation when the emissivity is 30, the absorbivity is 10 and the emissive power of black body is 4.

This implies that;

ε1 = Emissivity = 30
α1 = Absorbivity = 10
eb = Emissive Power of Black Body = 4

qnet = eb1 – α1)
qnet = 4(30 – 10)
qnet = 4(20)
qnet = 80

Therefore, the energy transfer by radiation is 80 J.

Calculating the Emissivity when the Energy Transfer by Radiation, the Aborbivity and the Emissive Power of Black Body is Given.

ε1 = (qnet / eb) + α1

Where:

ε1 = Emissivity
qnet = Energy Transfer by Radiation
α1 = Absorbivity
eb = Emissive Power of Black Body

Let’s solve an example;
Find the emissivity when the energy transfer by radiation is 28, the absorbivity is 3 and the emissive power of black body is 7.

This implies that;

qnet = Energy Transfer by Radiation = 28
α1 = Absorbivity = 3
eb = Emissive Power of Black Body = 7

ε1 = (qnet / eb) + α1
ε1 = (28 / 7) + 3
ε1 = 4 + 3
ε1 = 7

Therefore, the emissivity is 7

Calculating the Aborbivity when the Energy Transfer by Radiation, the Emissivity and Emissive Power of Black Body is Given.

α1 = ε1 – (qnet / eb)

Where:

α1 = Absorbivity
qnet = Energy Transfer by Radiation
ε1 = Emissivity
eb = Emissive Power of Black Body

Let’s solve an example;
Find the absorbivity when the energy transfer by radiation is 8, the emissivity is 18 and the emissive power of black body is 4.

This implies that;

qnet = Energy Transfer by Radiation = 8
ε1 = Emissivity = 18
eb = Emissive Power of Black Body = 4

α1 = ε1 – (qnet / eb)
α1 = 18 – (8 / 4)
α1 = 18 – 2
α1 = 16

Therefore, the absorbivity is 16.

Calculating the Emissive Power of Black Body when the Energy Transfer by Radiation, the Emissivity and Absorbivity is Given.

eb = qnet / ε1 – α1

Where:

eb = Emissive Power of Black Body
qnet = Energy Transfer by Radiation
ε1 = Emissivity
α1 = Absorbivity

Let’s solve an example;
Find the emissive power of black body when the energy transfer by radiation is 50, the emissivity is 15 and the absorbivity is 10.

This implies that;

qnet = Energy Transfer by Radiation = 50
ε1 = Emissivity = 15
α1 = Absorbivity = 10

eb = qnet / ε1 – α1
eb = 50 / 15 – 10
eb = 50 / 5
eb = 10

Therefore, the emissive power of black body is 10.

Nickzom Calculator – The Calculator Encyclopedia is capable of calculating the energy transfer by radiation.

To get the answer and workings of the energy transfer by radiation using the Nickzom Calculator – The Calculator Encyclopedia. First, you need to obtain the app.

You can get this app via any of these means:

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Once, you have obtained the calculator encyclopedia app, proceed to the Calculator Map, then click on Materials and Metallurgical under Engineering.

Now, Click on Radiation Heat Transfer under Materials and Metallurgical