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What is the refrigerant cycle?

An air conditioner works by taking in ‘ambient’ air from the environment and cooling the air down before expressing it again into your desired room or location. And it cools the air using refrigerant.

Liquid refrigerant is extremely cold. So when air comes into contact with the components inside your air-conditioning unit which contain the refrigerant, it cools too. It’s this cooler air which is then circulated around your home or office.

An air-conditioning unit works in a similar fashion to your fridge or freezer at home, containing refrigerant which flows through in a cycle through the system and changes state to provide its cooling output. 


How does the air-conditioning refrigerant cycle work?

The refrigerant cycle works on the laws of thermodynamics, and revolves around the refrigerant changing state between liquid and gas throughout the process, releasing energy into the system as it goes. You can read more about how energy is released during the ‘state change’ process, here.

There are four processes to the refrigeration cycle.


Step 1

An air-conditioning unit has a compressor, which pumps the refrigerant around the system. This is effectively the heart of your air-conditioning unit, and as the name suggests, it’s there to compress the refrigerant. 

Your refrigerant starts its journey in your air conditioner as a low-pressure gas, but when it passes through the compressor it becomes high-pressure. It’s heated by the compression process before flowing towards the condenser. 


Step 2

At the condenser, the now high-temperature, high-pressure gas releases its heat into the surrounding air. It condenses, and changes state to become a sub-cooled high-pressure liquid. 


Step 3 

Your high-pressure liquid refrigerant now passes through the unit’s expansion valve. Here, the pressure is reduced, meaning the temperature drops below the temperature of the refrigerated space. This results in cold, low pressure refrigerant liquid.  


Step 4 

In this final step, the low-pressure liquid refrigerant flows into the evaporator, where it absorbs heat from the indoor air to evaporate and become a low-pressure gas. The gas flows back to the compressor where the cycle starts all over again.  

This whole process involves the exchange of heat or energy between ambient air in the environment and the refrigerant itself. And, if you’re curious how a heat pump works, simply apply this same four-step process in reverse[SO1] !

Take a look at our range of air conditioners [SO2] for more information on how our world-leading, energy efficient air-conditioning technology cools your home or workplace, and explore our additional air-purification technology for the ultimate in clean, fresh air.

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