What is Adiabatic Process – Explanation

An adiabatic process is a thermodynamic process that occurs with no heat transfer between the system and its environment. In other words, the state changes, work can be done on or by the system during this change, but no heat energy is added or removed. Since no physical process can happen instantaneously and no system can truly be perfectly insulated, a perfectly adiabatic condition can never be achieved in reality. However, it can be approximated, and much can be learned by studying it.

The faster a process occurs, the closer it can be to adiabatic because the less time there will be for a transfer of heat.

What Is an Adiabatic Process?

An adiabatic process is defined as

The thermodynamic process in which there is no exchange of heat from the system to its surrounding neither during expansion nor during compression.

The adiabatic process can be either reversible or irreversible. Following are the essential conditions for the adiabatic process to take place:

  • The system must be perfectly insulated from the surrounding.
  • The process must be carried out quickly so that there is a sufficient amount of time for heat transfer to take place.

For instance, the gas compression within an engine cylinder is expected to happen so fast that on the compression process timescale, a minimum amount of the energy of the system could be produced and sent out in the form of heat.

Despite the cylinders being not insulated and having a conductive nature, the process is deemed to be adiabatic. The same could be taken into consideration to be true for the expansion process of one of these system.

What is Adiabatic Process Equation?

Following is the adiabatic process equation:

PVγ = constant


  • P is the pressure of the system
  • V is the volume of the system
  • γ is the adiabatic index and is defined as the ratio of heat capacity at constant pressure Cp to heat capacity at constant volume Cv

What is Adiabatic Expansion?

Adiabatic expansion is defined as an ideal behaviour for a closed system, in which the pressure is constant and the temperature is decreasing.

What is Adiabatic Compression?

Adiabatic compression of the air is defined as the compression in which no heat is added or subtracted from the air and the internal energy of the air is increased which is equal to the external work done on the air. The pressure of the air is more than the volume as the temperature increases during compression.

Adiabatic Process Example

There are several instances, some are stated below:

  • It is a process in which there may be a gas compression and heat is generated. One of the simplest examples would be the release of air from
    a pneumatic tire.
  • Adiabatic Efficiency is applied to devices such as nozzles, compressors, and turbines. One of the good applications of the adiabatic
  • The pendulum oscillating in a vertical plane is an example of it.
  • A quantum harmonic oscillator is likewise an example of an adiabatic system.
  • When we put the ice into the icebox, no heat goes out and no heat comes in.

Difference Between Isothermal and Adiabatic Process

Following is the table explaining the isothermal vs adiabatic process:

Isothermal processAdiabatic process
An isothermal process is defined as one of the thermodynamic processes which occur at a constant temperatureAn adiabatic process is defined as one of the thermodynamic processes which arise without any heat transfer among the system and the surrounding
Work done is due to the alternate in the internet heat content in the systemWork done is due to the change in its internal energy
The temperature can’t be variedThe temperature can be varied
There is a transfer of heatThere is no transfer of heat

Frequently Asked Questions – FAQs

What is Adiabatic process?

The adiabatic process is a thermodynamic process in which there is no heat transfer from in or out of the system. For an ideal gas, an adiabatic process is a reversible process with constant entropy. The mathematical representation of the adiabatic process is ΔQ=0

Which quantity remains constant in an adiabatic process?

In an adiabatic process, the total heat of the system remains constant.

If a cylinder containing a gas at high pressure explodes, the gas undergoes

When a cylinder containing a gas at high pressure explodes, the gas undergoes irreversible adiabatic change and fall of temperature.

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