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How Air Conditioning works 

The Cooling (Vapour Compression) Cycle

The Components

An air conditioning unit unit has three main parts. A compressor, a condenser and an evaporator.

The Locations

The condenser and the compressor are housed outside, usually hung on the wall of your building. In the case of a marine system, the condenser is cooled by seawater meaning the condensing unit can be hidden in the engine room or similar.

The evaporator is located inside the place it is cooling these two parts are interconnected with copper piping.

The Cycle

Refrigerant gas begins its cycle at the compressor as a low pressure low temperature vapour.

The compressor then compresses the gas which brings the molecules closer together. The closer they are, the higher the energy and temperature. 

The refrigerant then leaves the compressor as a high pressure, high temperature vapour and flows to the condenser. 

The condenser will have a fan fitted near the matrix (radiator) to cool it and doing so dissipates the heat from the refrigerant.

On leaving the condenser the refrigerant is cooler and has changed from a gas to a liquid under high pressure.

The liquid then flows to the TEV (Thermostatic Expansion Valve), a small orifice which thermally controls the rate at which refrigerant flows into the evaporator. 

On the other side of the TEV the pressure drops and as it does, so the liquid begins to evaporate into a gas.

As the liquid changes back into a gas inside the evaporator it extracts the heat around it, again assisted by a fan which cools the room.

As the refrigerant leaves the evaporator, it is once again a low temperature, low pressure vapour and the cycle begins again.

The Heating (Heat Pump) Cycle

The components

How a heat pump works. The principal is similar in that the same components are used but the refrigerant runs in the opposite direction by way or a reversing valve. The evaporator becomes the condenser and vice versa. 

The Cycle

Refrigerant leaves the compressor as a high temperature high pressure gas vapour and enters the Condenser (normally the evaporator) 

The refrigerant releases its heat to the air and turns into a liquid state

The liquid then passes through the TEV and into the Evaporator (normally the Condenser)

The refrigerant absorbs heat from the air and boils to a low pressure low temperature vapour once again returning to the compressor and the cycle begins again.

In the case of a marine water cooled system the refrigerant absorbs heat from the sea water and boils to a vapour returning to compressor.

  Please email or call us for more information and advice 

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