COMPRESSOR

The Pressure Increaser

What does the compressor do?

Within a cooling system, the compressor is the component that pumps gas from low pressure to high pressure; turning refrigerant into a liquid to start the process in a continuous cycle.

How does the compressor raise gas pressure?

Remember the Gas Law we mentioned earlier?

‘When the volume is decreased, the pressure increases.’ 

 

The compressor (as the name suggests) compresses the gas, thereby decreasing the volume and pushing up the pressure.

At a basic level, a piston in a cylinder is what makes up a compressor. The piston pulls out and pushes down – just like when you’re pumping up your bike tyres.

You may also notice that the end of your pump has become extremely hot whilst vigorously pumping up that tyre, and even though your dad might have warned you as a kid.

‘CAUTION HOT! DO NOT TOUCH!’

You couldn’t help but think to yourself, 

‘but how hot?‘

 – So you’d touch it … and burn your finger.

The purpose here is that we’re trying to bring heat around the system.

But heat and temperature aren’t the same things.

Temperature is the average speed at which molecules move within a substance, whereas heat is the amount of energy in a system.

Let’s use this example, let’s say you have a water tank at 25°C; this much water increased by 1 degree would take 1600KJ of energy!

In contrast, a spark (to ignite an engine) burns at about 1300°C and has an energy of about 30mJ, or 0.00003KJ.

We can manipulate the temperature velocity by changing the volume of the refrigerant (the space that it can occupy), and that’s what we’re doing when we compress it; we’re causing it to occupy a smaller area which increases the pressure and temperature.

When we decompress, we allow it to occupy a larger space, decreasing the pressure and temperature.

 Which moves us over to the condenser…