2. Indirect cooling

In view of the legal requirements concerning the containment of installations, and despite the contradiction between the risk of leakage from direct circuits and the over-consumption of indirect circuits, the general trend is towards indirect systems, which are safer and whose energy consumption is reduced.

These circuits use a refrigerant to transfer cooling energy from the cooling units to the user stations. Naturally, in the case of heat pumps, they can also transfer thermal energy with a coolant to other stations.

In air-conditioning systems, the refrigerant is generally pure water; its use is limited to an outlet temperature of around 3°C in chillers. If the units are to be shut down in winter and exposed to frost, an antifreeze must be added.

As soon as the temperature to be achieved is close to 0°C to 1°C,...