Single-circuit cooling system is used to cool down process and devices which have within a certain period of time a constant cooling water flow. Normally such cooling systems are used for production lines which function with ON/OFF regime as a whole.

Pumps, which ensure water flow, pump cold water from the cooling water pool and they supply it to the consumers. The water heated by the consumers is directed to cooling towers to be cooled again. Cooled water is then directed back to cooling water pools.

In open system of cooling towers a part of energy is transmitted by means of heat transfer from water into the air, one part is released through evaporation. That kind of cooling systems is used, when temperature of cooled cooling water is some degrees higher than the one of the wet bulb thermometer.

Due to a constant evaporation, when water is released from the system in the form of water vapour, the concentration of other substances is rising, which is also called condensed water. When the level of such concentration is too high, solubility of individual salts would be exceeded giving rise to formation of sediments and deposits, and the occurrence of corrosion on cooling system materials. For this reason a part of the system water is discharged and replaced by fresh water with a lower concentration of dissolved substances. This way we keep balanced quality of the system water in the system where eventual problems occurred by sediments, deposits or corrosion are manageable. Such water release is called TDS. In more modern systems this task is performed by automatic devices.

For a proper functioning of the system we need to take care of an adequate preparation of supplying water and the system water treatment as well.