Peltier Effect

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Introduction to Peltier Effect

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The entire experiment is based on the purpose of the heat generator that also derives from the Peltier effect application. 

Here, we find a different concept of the Peltier effect. The experiment called ‘Peltier effect’ was discovered by a French scientist in 1834. The concept was named after him.

This experiment is all about absorption or radiation of heat effect when there will be the passage of electrical current. We call the electrical junction a Peltier junction.

The concept of LJ effort is the fact where heat is given out when an electrical current is passed across the junction of two materials. Detailed information on the Peltier effect in thermocouple has been provided here.


Peltier Effect and Thomson Effect

The Peltier effect and Thomson effect possess some similarities. Thomson effect is something which states that the generation of reversible heat is possible when the passage of electrical current is sent via a conducting material under a certain temperature gradient.

The thermoelectric cooling devices are dependent on the Peltier effect. Each effect generated from the Peltier experiment is meant to convert the electrical energy into a temperature gradient.

However, we will study it later. Let’s clarify all your doubts on Peltier effect efficiency. The efficiency of the Peltier modules is found to be around 5% only. Also, it is concluded that there is an additional loss of 3% during the process.

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In the above figure, the electric current is travelling through a circuit comprising two different Peltier materials. One Peltier device called a couple consists of one n-type and one p-type semiconductor pellet. 

The charge carries the negative electron and positive holes. This behaviour also promotes the transport of heat. Thermoelectric coolers (TECs) are used as Peltier effect devices. These devices are suitable for Peltier effect as they act as the beast heat exchanger between two electrical junctions.


The TECs Have Certain Benefits for Which it is Used in the Peltier Effect. Those Points Are:

  • Long lifetime

  • Low maintenance

  • Controllable

  • Tolerate extreme environments

  • Highly Performance-based

  • No emission of any chlorofluorocarbons or refrigerants

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The Experiment of Peltier Effect Gives Two Annotations Such As

  1. Heat is evolved at one junction

  2. Heat is absorbed in the other junction

This is why the Peltier effect is considered as the converse of the Seebeck effect. So, the electric current is passed through a fuse consisting of its two dissimilar junctions. Heat is at one and absorbed at another junction. This is the basic output of the entire Peltier effect.

The Seebeck effect behaves like the opposite of the Peltier effect as they do not keep their function in one path but in two different ways. 

You can visualize from the figure that the current is able to pass within the two dissimilar natures, such as one is the absorption of heat, and another is releasing heat. 


Peltier Thermocouple

In a Cu-Fe thermocouple, the current flows from Cu to Fe, at junction number 1. In this case, the heat is absorbed. So, the thermocouple gets cooled.

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However, in junction 2 you notice that the current flows from Fe to Cu and heat is liberated. That is why it gets heated. 

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The reverse of the current occurs during this experiment. This initiates a healing effect at junction 1 and initiates the cooling effect at junction 2. This is why the Peltier effect is considered a reversible process. The reversible process is dependent on the direction of the current. 

The Peltier effect is a fact that depends on the passage of electric current and the absorption or rejection of heat current. Here, heat energy is absorbed or sent out from a homogeneous conductor. The Peltier effect is something that enables us to detect the different flows of electricity

The accompanying heat current is a type of electric current that can be explained by the different velocities of the flow of the electrons. All of these electrons are an active carrier of electric current. The electric flow of the current has certain velocities. Each electron’s velocity depends on the conduction electrons’ energies.


Peltier Coefficient

Peltier coefficient can be denoted as the total amount of heat evolved or absorbed at one end of the junction of a thermocouple during the passage of one ampere of current flows through it within one second (one coulomb). 

Pie ‘π’ is the symbol that is used for the Peltier coefficient. The unit of measurement is volt. Assume that H is the total heat absorbed or sent out at one point, then the formula for Peltier effect is:

H = π I t

Here, t = total time

I = current flow through the conductor

π = Peltier coefficient

Peltier electromotive force or Peltier emf is found at that junction where the Peltier coefficient is found. The co-efficient relies on certain facts such as the pair of metals in contact and the junction’s temperature.


FAQ (Frequently Asked Questions)

1. How do you define the Seebeck effect?

Seebeck effect is one of the electromotive forces that is produced consequently due to the electric current loop inside the material. The materials are responsible for the looping of electric current as two junctions are kept under different temperatures. This effect was put forward by the German physicist Thomas Johann Seebeck in 1821.

2. What do you mean by the basic principle of the Joule-Thomson effect?

Joule-Thomson effect states that the alteration of temperature leads toward the expansion of gas without any work or transfer of heat. This is the vital and basic principle that lies within the Joule-Thomson effect.

3. Explain the reversible effect. Give some examples.

Reversible effect is a process where the entire phenomenon is not remaining in the permanent phase. Each process under a reversible effect can go back to its initial phase. Some of the toxic chemicals follow some reversible effects during the reactions. For instance, reversible effects are compression and expansion of gases, slow isothermal compression, and expansion of gases.

4. Find out the total heat energy of the current of 10 A passing through the conductor for 2 minutes of time with the Peltier efficiency 60 μV/K.

H = π I t

Here, t = 2 min

I = 10 A

π = 60 μ V/K

So, total heat H = 60 * 10 * 2 = 1200 J = 1.2 KJ