Cool drying is, as is known, based on the principle that by lowering the gas temperature the moisture in the gas condenses, after which the condensate is separated in a liquid separator and after which the gas is again heated such that this gas is no longer saturated.
It is known that in most cases compressed air, supplied by a compressor for example, is saturated with water vapour or, in other words, it has a relative humidity of 100%. This means that in the event of a temperature drop to below the ‘dew point’ condensation occurs. Because of the condensed water corrosion occurs in the pipes and tools that draw off compressed air from the compressor, and equipment can present premature wear.
It is consequently necessary to dry this compressed air, which can be done in the aforementioned way by cool drying. Air other than compressed air or other gases can also be dried in this way.
A method for cool drying is already known whereby the condenser is an air-cooled condenser that is equipped with one or more fans.
These fans can be switched on and off depending on the cooling required for the condenser and coolant.
These fans will be switched on at a certain threshold value and switched off again at another threshold value.
Hereby more cooling is often done than is strictly necessary in order to have a certain reserve, such that the energy consumption of such a fan is often higher than what is really necessary.
The switching on or off of the fan will vary the condenser pressure.
This has the disadvantage that when the condenser pressure rises, the compressor will consume more power.
An additional disadvantage is that the varying condenser pressure affects the expansion means and other valves in the cooling circuit, and consequently also the evaporator pressure and cooling capacity of the cooling circuit.
Consequently the expansion means and other valves must be adjusted in order to prevent fluctuations of the evaporator pressure.
This leads to a very complex control of the system.