Unit 305 Session 9 Principles of refrigeration gas

​Refrigerants

Open Ended

What do you think a Refrigerant is?

​Refrigerants are fluorinated chemicals that are used in both liquid and gas states.

They can, therefore, be classified as both liquid (when compressed) and gas

(vapour). All refrigerants boil at extremely low temperatures, well below 0°C.

​When a refrigerant gas is compressed, it changes its state to a liquid.
During this process a lot of heat and pressure are generated.

​When the pressure is released quickly, it generates cold. Refrigerants’ ability to change their state quickly with such wide temperature changes allows them to be used in air conditioning systems and heat pumps. The process is known as the vapour compression refrigeration cycle.

4. The vapour/liquid mix passes through

the evaporator, where final expansion to a vapour takes place. This then enters the compressor for the cycle to begin again

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1. The refrigerant vapour enters the compressor, which compresses it, generating heat.

2. The compressed vapour then enters the condenser, where the useful heat is removed and the vapour condenses to a liquid refrigerant.

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3. From here, the liquid refrigerant then passes into the expansion valve, where rapid expansion takes place, converting the warm liquid into a super-cold vapour/liquid mix, which creates the refrigeration effect.

Multiple Choice

When refrigerant gas passes through the compressor it?

• Cools

• Heats up

Multiple Choice

When a refrigerant gas passes through the expansion valve it ?

• Gains heat

• Looses heat

Hotspot

Where is the expansion valve?

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Where is the compressor?

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Where is the Evaporator?

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Where is the condenser?