Adiabatic Process: Formula, Work Done and Real-Life Examples

An adiabatic process is a concept that explains how a system can change without exchanging heat with its surroundings. You may not notice it, but this process happens in real life, like when air is compressed in a pump or released quickly from a tire.

Have you ever noticed that when you pump air into a bicycle tire, it gets warm? Interestingly, that is related to adiabatic process. This article guides you through the complete idea of the adiabatic process in a simple and clear way.

Table of Contents

• What is an Adiabatic Process
• Pressure-Volume (P-V) Diagram of Adiabatic Process
• Calculation of Work Done in Adiabatic Process
• Understanding Adiabatic Expansion and Compression
• Adiabatic Process Examples in Real-Life

What is an Adiabatic Process

An adiabatic process is a thermodynamic process in which no heat is exchanged between the system and its surroundings. In this process, heat neither enters the system nor leaves it during the transformation. 

So, in simple words, we can say, 

“An adiabatic process is a thermodynamic process in which there is no exchange of heat between the system and its surroundings.”

Interestingly! Adiabatic processes usually happen very quickly, which does not allow enough time for heat transfer to take place. These processes are commonly observed in gases during rapid compression or expansion. 

Pressure-Volume (P-V) Diagram of Adiabatic Process 

The P-V diagram for an adiabatic process shows the relationship between pressure (P) and volume (V) during the process. In this graph, pressure and volume change continuously without any heat exchange between the system and the surroundings.

Now, there’s an interesting question that comes into the picture: what happens when the volume changes?

• When the volume increases, the pressure decreases.
• When the volume decreases, the pressure increases.

The P-V curve of an adiabatic process is steeper than the curve of an isothermal process. This happens because the temperature changes rapidly during an adiabatic process, as no heat enters or leaves the system.

Now you may ask, does this really happen in real life?
The fact is, perfect conditions are rare, but many processes behave almost like adiabatic ones.

Now, there’s an interesting question that comes into picture: how do we represent this process mathematically?

The mathematical representation of the adiabatic process formula is:

PVγ=constant

Where P is pressure, V is volume, and  γ is the ratio of heat capacities ( Cp/Cv)

Moving ahead, this equation shows how pressure and volume are related when no heat transfer takes place.

Calculation of Work Done in Adiabatic Process

The work done in an adiabatic process depends on the initial and final pressure, initial and final volume, and the adiabatic ratio of the system.

Interestingly! Since no heat exchange takes place in an adiabatic process, the work done directly affects the internal energy of the system.

• During adiabatic compression, work is done on the system, so the internal energy increases.
• During adiabatic expansion, work is done by the system, so the internal energy decreases.

The formula for work done in an adiabatic process is:

W=PfVf−PiVi1−γ

Where,

•  Pf= Final pressure of the system
•  Vf= Final volume of the system
•  Pi= Initial pressure of the system
•  Vi= Initial volume of the system
•  γ = Adiabatic ratio or specific heat ratio

Understanding Adiabatic Expansion and Compression

When no heat is exchanged, all changes in temperature happen due to internal energy. That’s why compression increases temperature, while expansion decreases it. 

Adiabatic Expansion

Adiabatic expansion happens when a gas expands without heat exchange.

• Gas does work on its surroundings

• Internal energy decreases

• Temperature drops

Imagine releasing air from a balloon quickly; the air feels cool. This is a clear adiabatic process example. 

Adiabatic Compression

Adiabatic compression happens when a gas is compressed by applying external pressure. 

• Work is done on the gas

• Internal energy increases

• Temperature rises

But how? When a gas is compressed, its molecules move closer together. This increases their energy, which raises the temperature. This clearly shows the work done in an adiabatic process.

Adiabatic Process Examples in Real-Life

Let’s take a quick look at some simple and familiar situations where the adiabatic process takes place. These examples will help you better connect with what an adiabatic process is in real life.

• Air compression in a bicycle pump: Have you ever noticed the pump getting warm? This happens because air is compressed quickly, increasing its temperature without any heat exchange. It clearly shows the work done in an adiabatic process.
• Rapid release of gas from a tire: When gas escapes suddenly, it expands very fast and cools down. There is no time for heat transfer, making it a perfect adiabatic process example.
• Working of engines and compressors: In machines like engines, gases are compressed and expanded rapidly. These fast changes occur without heat exchange, which is why they follow the adiabatic process formula.
• Expansion of gases in the atmosphere: As air rises, it expands due to lower pressure and cools down. This natural process is another clear example of an adiabatic process seen in weather changes.
• Cooling of Spray Can: Have you ever noticed that a spray can feels cold after use? This happens because the gas inside the can expands rapidly. Since the expansion occurs without heat exchange, the temperature of the gas decreases, causing the can to become cold. 
• Hiking in High Altitudes: As people move to higher altitudes, air pressure decreases, and the air expands adiabatically. This expansion lowers the temperature of the air, making mountain regions cooler even during daytime. 

In this article, we have learned that the adiabatic process is a thermodynamic process where no heat exchange takes place. We also explored the adiabatic process formula and saw real-life examples. This concept plays an important role in both everyday life and different engineering applications.