# Calculating the work needed to compress a volume of air

• Minesh
In summary, the person is seeking help to find the formula for calculating the work done to compress a volume of air, and is interested in understanding this for both isothermal and polytropic processes. They also want to know how to incorporate resistance due to friction in the calculation. They have defined the initial parameters and assume the process to be quasi static. They mention using an integral for the calculation.
Minesh
TL;DR Summary
Need help to figure out the formula for work done for compressing a volume of atm. air using isothermal and polytropic process
Hi All,

I am working on an engineering problem, where i have to calculate the total work needed to compress a volume of air (Locked in a cylindrical chamber similar to an IC chamber where the piston moves to compress the air mixture)

I am defining the process with the below initial parameters,
1. Uncompressed volume of the chamber
2. Compression Ratio
3. States (Pressure and Temperature) before compression corresponds to that of atmospheric values.
4. I assume the process to be a quasi static process

In addition i would also like to know how to add the resistance due to friction of the moving piston into this calculation.

I wanted to know the formula to understand how the work done varies with volume of the air chamber.
Also, i am interested in knowing this from the view of both isothermal and polytropic process.

Hello Minesh, !

Minesh said:
formula for work done for compressing a volume of atm. air using isothermal and polytropic process

4. I assume the process to be a quasi static process

I wanted to know the formula to understand how the work done varies with volume of the air chamber.
You do $$\int p \,dV$$
In addition i would also like to know how to add the resistance due to friction of the moving piston into this calculation.
You add ##\int F_\text {friction}\, ds##

russ_watters and Minesh
Minesh said:
Summary:: Need help to figure out the formula for work done for compressing a volume of atm. air using isothermal and polytropic process

Hi All,

I am working on an engineering problem, where i have to calculate the total work needed to compress a volume of air (Locked in a cylindrical chamber similar to an IC chamber where the piston moves to compress the air mixture)

I am defining the process with the below initial parameters,
1. Uncompressed volume of the chamber
2. Compression Ratio
3. States (Pressure and Temperature) before compression corresponds to that of atmospheric values.
4. I assume the process to be a quasi static process

In addition i would also like to know how to add the resistance due to friction of the moving piston into this calculation.

I wanted to know the formula to understand how the work done varies with volume of the air chamber.
Also, i am interested in knowing this from the view of both isothermal and polytropic process.

What is your approach to this so far?

## What is the definition of work in a scientific context?

In the context of science, work is defined as the force applied to an object multiplied by the distance over which the force is applied.

## How is work calculated when compressing a volume of air?

The work needed to compress a volume of air can be calculated by multiplying the change in pressure by the change in volume.

## What is the unit of measurement for work?

The unit of measurement for work is joules (J).

## Can the work needed to compress a volume of air be negative?

Yes, the work can be negative if the volume of air is expanding instead of being compressed. This means that work is being done by the air instead of on the air.

## What factors affect the amount of work needed to compress a volume of air?

The amount of work needed to compress a volume of air is affected by the initial and final volume, as well as the initial and final pressure of the air. Other factors such as temperature and the type of gas can also play a role.

• Mechanical Engineering
Replies
13
Views
428
• Mechanical Engineering
Replies
8
Views
1K
• Mechanical Engineering
Replies
5
Views
2K
• Mechanical Engineering
Replies
4
Views
2K
• Mechanical Engineering
Replies
5
Views
1K
• Thermodynamics
Replies
3
Views
1K
• Mechanical Engineering
Replies
5
Views
249
• Mechanical Engineering
Replies
8
Views
2K
• Mechanical Engineering
Replies
15
Views
2K
• Mechanical Engineering
Replies
6
Views
1K