MULTI Kühlsysteme

Closed stainless steel cooling towers KI & KUI

Closed stainless steel cooling towers: cooling equipment and application

A cooling tower with a closed cooling circuit is different from an open cooling tower in that there are two separate water circuits within the cooling tower. The cooling water with the thermal load flows in a closed circuit. The thermal load is dissipated to the ambient air via the tube bundle. Most often, this circuit is called “primary cooling circuit“. In addition, in an open circuit, different cooling water is sprayed across the tube bundle. Part of this water will evaporate on the surface of the tubes and will thus provide an additional cooling effect. This circuit is called “secondary cooling circuit“.

The cooling technology of the closed system offers you three essential benefits:

1. The internal cooling circuit without contamination is also appropriate for sensitive products such as in the food processing industry.

2. From certain outside temperatures, dry operation is also feasible In Winter time, this will save water and energy costs in the cold season.

Applications and characteristics

Closed stainless steel cooling towers
  • Industrial applications in all common industries and building technology
  • Particularly suitable for high cooling water quality requirements e.g. cooling of machines with tight cooling channels
  • Ambient air has no direct contact to cooling water
  • For inside and outside installation
  • Water inlet temperature to 75°C
  • Cooling water temperatures depend on ambient air temperatures and -humidity customizable by speed control of the fans
  • Operation mostly with water-glycol-mixture
  • Design for best utilization of floor space
  • Modular design allows maximum adaption to all required performances
  • High-effective silencers available
  • Easy maintenance
  • Accessories for almost all kinds of applications
  • Easy accessibility of fittings and pumps
  • Precautionsnecessary for winter operation
  • At part load operation and at lower ambient temperatures, the cooling tower can be operated without water spray
  • Special designs and wide range of accessories available
  • Easy to install
  • Water treatment for supply water required


Closed stainless steel cooling towers
  • Stainless steel housing
  • Low-noise by pressure side centrifugal fans in stainless steel construction
  • Air is "pressed" through the cooling tower
  • Water distribution by stainless steel pipes
  • Pollution secured plastic spray nozzles
  • Smooth pipe heat exchanger made of steel, outside hot galvanized
  • Spaying circuit completely piped, with external pump
  • High-quality three-phase asynchronous motors according to IEC 34-1 with aluminium die-cast housing
  • Motors with 2 speeds or with 1 speed for operation with frequency converter for power control
  • V-belt pulleys made of cast steel with locking bushes for easy exchange

Mode of action

The (evaporative) cooling tower is a wet water / air heat exchanger. In a closed cooling tower the water to be cooled or water-glycol mixture is cooled within an integrated tube bundle heat exchanger. The outside of the heat exchanger is sprayed in a secondary circuit with water. A small amount of the secondary circuit water evaporates, the therefor required evaporation heat is taken from the system and leads to the desired cooling. With appropriate application in the cold season, a dry operation is possible.

Due to the evaporation process water losses arise. These losses must be supplied to the circuit at a suitable point.