Types of Conduction

Conduction, or heat transfer, results from microscopic collisions of particles and the movement of electrons in an object. This heat transfer usually takes place in three states of matter – solid, liquid and plasma. 

In this article, we will explore the topic of conduction and its types, along with a detailed discussion of two major types of conduction. The discussion will also include several important related concepts you should definitely not miss!

What is Conduction?

In physics, conduction is one of the three prominent phenomena responsible for transferring heat energy from one place to another. Two other processes are radiation and convection. In contrast with these two processes, conduction refers to the transfer of heat energy from one atom or molecule to another. 

It usually occurs in solids and liquids where the particles are kept closer than gas, where the particles are kept apart. However, there is no significant change in the position of molecules as the process of conduction takes place.

Further, it is also important to note that the rate of energy transfer through conduction is comparatively higher than the difference between substances in contact. 

Examples of types of conduction include the functioning of iron rods. Whenever it is placed above a heated surface or fire for a few minutes, the temperature of the handle increases. 

What do we infer about this change?

Well, what actually is happening here is that heat is transferring from the surface above to the handle below due to conduction along the iron rod length. Thus, the heating of the iron rod takes place.

Transient Conduction or Non-steady Conduction

As referred from the term itself, transient means non-steady. Thus, it is a type of conduction process if the body’s temperature varies with time and there are few abrupt changes in the surface temperature. After a few intervals, the temperature usually attains equilibrium (gets in a steady state).

During this time, the body is in an unsteady or transient state as the temperature differs with time. This process is what we call transient conduction or Non-steady conduction. 

As we get familiar with the concept of non-steady conduction, let us go through the formula to calculate the total heat transfer between a body and the environment over a given period.

it is given by Q = m Cp [Tf – Ti] 

Non-transient Conduction or Steady-State Conduction

Non-transient conduction is one of the types of conduction we discussed in previous sections. This process is exactly the opposite of what we discussed above. Non-transient or steady-state conduction occurs when there is no significant change in temperature at all locations with time. It is mathematically represented as ∂t/∂τ = 0, where most of the practical applications are catered. 

In the case of steady-state conduction, all partial derivatives of temperature are either retained at 0 levels or non zero values, but any derivative of temperatures about time remains constant at zero. In insect cases, the amount of heat entering any area of an object usually does not differ from the amount of energy released from it. Thus, the thermal energy is trapped in that region regardless of whether the temperature rises or falls.

Let us take an example to understand this. An object may be cold from one end and hot from the other. But once it achieves the state of steady-state conduction, there will be no significant change in the special gradient of temperatures along with the object as time passes.

Comparison – Steady-state Conduction vs Non-steady State Conduction

Now that we are aware of the types of conduction, let us perform a comparative analysis of both terms to understand the differences between them better.

Here are a few points of distinction between the two terms –

• The first and most significant difference between steady-state conduction and unsteady state conduction is that the object’s temperature does not change the time in the case of steady-state conduction. However, the object’s temperature keeps on changing as per time in the case of unsteady conduction.
• In the case of non-steady-state conduction, the object experience is heat diffusion which is not the case in steady-state conduction.
• There is no change in the object’s internal energy in the case of steady-state conduction. However, the shift in an object’s internal energy does not equate to zero in the case of non-steady-state conduction. 
• In the case of steady-state conduction, energy entering the object equals the energy leaving from it. However, in the case of non-steady-state conduction, It is not equal.

Conclusion

In conclusion, we can say that the two types of conduction are non-steady-state conduction and steady-state conduction. While the two categories of head conduction mainly differentiate based on how temperature reacts in response to time changes, there are several differences depending on other factors. 

These may include how they are denoted, the changes in temperature as time changes, and the state of energy as it enters the object and leaves. In a nutshell, it can be concluded that as we study types of conduction notes, it is also equally necessary to look at the difference between the two modes of heat transfer.