Refrigerants are used for a wide range of heating and cooling purposes. They are used in fridges, freezers, air conditioning units, and many other mechanical devices. There are different types of refrigerant in use today. So what are refrigerants, and how do they work?

What is a Refrigerant< p>

A refrigerant is a compound which can reversibly change phase from liquid to gas and vice-versa for the purpose of heat transfer. The thermodynamic properties of refrigerants allow them to absorb and expel heat energy via evaporation and condensation.

On a hot summers day you sweat to cool you down. The way it works is that the liquid in the sweat evaporates, using up heat energy in the process, and cools you down. The heat energy stored in your body is used to give the energy needed for the liquid to evaporate. This then has the net effect of cooling your body down as heat energy transfers away from it.

Refrigerants in a refrigerator or air conditioners for example work using the same principle.

How Refrigerants Work

To turn a liquid into a gas, heat energy is required. With a pan of water, we apply heat and the water turns to steam. Steam is also known as the gaseous phase of water.

Refrigerants likewise require heat energy to turn from liquid to gas. In your air conditioning system, the refrigerant changes phase from liquid to gas using the heat in the air that is passing over the evaporator heat exchanger. To achieve cooling, liquid refrigerant is forced through a tiny gap at high pressure. This has the effect of making the liquid evaporate into a gas, and uses up heat energy in the process.

The refrigerant, in it's gas stage, is then drawn through the compressor. This has the effect of compressing the molecules tighter and tighter, turning the refrigerant back into a liquid phase. This liquid refrigerant is usually very hot as it contains all the excess heat which was used to cause expansion of the refrigerant in the heat exchanger.

The liquid refrigerant is then fed through a second heat exchanging coil. The excess heat load is then dumped into the air passing over the heat exchanger. This side of the system is known as the condenser.

The cooled refrigerant liquid is then fed back from the condensing coil through to the expansion valve again and the process starts over. 

The Ozone Layer

Ozone damaging refrigerants are being slowly phased out. Until recently, many refrigerants contained chlorine as part of their chemical makeup. The chlorine has an adverse effect on the ozone layer, causing it to break down.

The highly toxic and polluting refrigerants of yesterday are no longer being used in newly manufactured equipment. The old air conditioning systems which rely on them are being replaced one by one as they develop faults and are beyond repair.

R410a is the newest refrigerant in widescale use for air conditioning purposes. It does not contain any chlorine molecules and is ozone friendly. All major manufacturers are now producing air conditioning and heat pump systems ustilising the newer and more environmentally friendly refrigerant R410a.