Modes of Heat Transfer-(Conduction, Convection, and Radiation), PDF

Before going to study the heat transfer in details lets have an overview on Heat first.

So Heat is the form of energy which is associated with the motion of molecules or atoms. The heat transfer takes place from the high-temperature body to low-temperature body.


When we cook food. Initially, we provide heat and after preparing food we are trying to extract heat to eat the cooked food. So what we do for, we are keeping to an open environment or near to fan. So the temperature of the air is less than the temperature of cooked food, it (temp) starts emitting to surrounding and this process goes on till both come in the normal temperature.

The extreme or moderate or low heated object leaves the heat at the room temperature. Now further it has been categorized in the 3 types which are:

Modes of Heat Treatment:

There is a total of 3 Modes of Heat transfer which is:

  1. Conduction
  2. Convection and
  3. Radiation

1. Conduction:

In Conduction, the heat or energy is transferred by a direct contact like when any heated object you touch with your hand the conduction process take place.

When we heat the Iron at one side the other side automatically gets heated because the molecules present in it travels to another side and heated that area too. So we can say Conduction is equal to Direct contact.

It is defined as the transfer of heat by means of molecular agitation within a material without any motion of the material as a whole.

2. Convection:

In convection, the heat or energy is transferred by mass motion of fluid which might be air or water when heated fluid is caused to move away from the source of heat-carrying energy with it.


When the heat is provided to water at the bottom the pot is heated, the water particles move faster, and they also move farther apart. So now the heated water becomes less dense and we know the less-dense fluid will float on top of a more dense one. Now, the heated water rises in the pot. The surrounding cooler water flows into its place. This flow creates circular motion, known as convection currents. 

Application is :

3. Radiation:

The Radiation is defined as Everybody emits radiation in the form of an electromagnetic wave or rays or particles. In this process does not require a medium to transfer the Thermal (Heat) energy.


In summer when you go in the field and for a time you stand there you will feel heat up because of sun emits the heat and your body skin receives. That is how the radiation process works.

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Anup Kumar Dey

A Mechanical Engineer with 19 years of working experience in various renowned MNCs.

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