How do you distinguish between internal and external irreversibilities?

An Irreversible process is one in which heat is transferred through a finite temperature. Irreversible process is also known as spontaneous process because these processes take place at very fast rate.

Examples of irreversible processes are as follows:

1) Relative motion with friction

2) Falling of the water from the hill

3) Electricity flow through a resistance.

4) Throttling process

5) Plastic deformation

Irreversible processes are of two types:

1) External irreversibility:

These are associated with dissipating effects outside the working fluid.

For example: mechanical friction occurring during the process due to some external source.

2. Internal irreversibility:

These are associated with dissipating effects within the working fluid.

For example: Unrestricted expansion of the gas, viscosity and inertia of the gas.