As the name implies, an Irreversible process is any process that cannot be reversed after it has begun. In simpler words, the system where the process takes place and its environment cannot retain its initial state after the process. It usually takes place naturally, though these are also called natural processes. Some general irreversible processes are combustion, heat exchange, energy-burning, mass exchange, etc. Moreover, this irreversibility is dependent on several factors. Primary factors include friction, heat loss, natural fluid expansion and intermixing of inseparable chemicals.

Moreover, the topic of the Irreversible process is broad enough. It has many other aspects. Let’s dive directly into details.

About Irreversible Process

As given in thermodynamics, an irreversible process can be described as a process that cannot be reversed and return the system and its surroundings to their initial state. For example, A bus while travelling on a mountain will burn a lot of petroleum. But, this petroleum won’t come back while coming back.

Here, combustion takes place during the burning of petroleum. It cannot be reversed, and we can also depict that combustion is an irreversible process. They are uncontrolled and occur naturally, though they are also referred to as Natural processes. Before discussing the Irreversible process, let’s understand the reversible process to see the difference between these two. 

Reversible Process

• This is the converse of an irreversible change. Here, the system and surroundings where a process has taken place can retain the same initial state. Also, they can be reversed without affecting the universe’s thermodynamic characteristics. The reversible process can be reversed, leaving no evidence that the system underwent a thermodynamic change.

What Are The Factors That Cause A Process To Be Irreversible?

Several dynamics decide whether a process is irreversible or not. Some triggering factors are friction, unregulated expansion, inseparable mixture, or irreversible heat transfer. For instance:-

• The friction transforms the power of the fuel to generate heat
• The unregulated expansion of the fluid prohibits the fuel from returning to its original form. 
• Processes do not take an infinite amount of time to complete. However, the reversal of heat exchange takes place through a fixed temperature due to the uncontrolled state of the forwarding operation.
• Intermixing of two different chemicals that can’t be separated because the process is natural.

Types of Irreversibility

Thermodynamics denotes that a physical process is thermodynamically irreversible after the overall energy of the systems and its reservoir increases to a positive value. There are two types of irreversible processes. Generally, there are two types of irreversibility: External irreversibility and Internal Irreversibility. Firstly, external irreversibilities can be described as a situation where dissipation takes place outside the system, in the surroundings. While on the other hand, Internal Irreversibilities are when the dissipation takes place inside the system.

What Are the Characteristics Of The Irreversible Process?

• Here, significant changes take place in a limited amount of time
• Heat transfer happens in irreversible process Due to a fixed difference in temperature
• Mass transfer occurs due to a fixed chemical potential difference.
• The stream of fluids can also depict its contact pressure and drag force among any two matters.
• Irreversible processes are significant changes in a finite amount of time with actual materials.
• Any infinitesimal changes cannot change the process’s direction in external systems.

Examples

• Inelastic deformation is an example of an irreversible process.
• When the total entropy is positive, no one process can get reversed.
• An example of an irreversible process is electric current flow through a conductor with a resistance.
• A spontaneous chemical or electrochemical reaction is an example of an irreversible process.
• Magnetisation or polarisation with hysteresis is an example of an irreversible process.

Conclusion

From all the above, we came through the concept of Irreversible Processes. We learned about the irreversible process, its types, the factors it depends on, characteristics and examples lastly. In a nutshell, Irreversible processes can be referred to as the process which cannot be reversed after it has begun. This process is converse to a reversible process. Here, the surroundings and systems cannot retain their initial state. Moreover, combustion, intermixing of inseparable chemicals, heat and mass transfers are some examples.