Cooling a fluid or condensing a gas via evaporative cooling is all-natural, using water as the cooling medium and efficiently dissipating heat into the sky.

Principle of operation

The cooling process is achieved via close water/air contact, and transfer of heat to the air by small scale water evaporation. The heat is then dissipated via the warm, saturated discharge air.

Principle of operation


  1. Hot water in
  2. Water spray distribution system
  3. Heat transfer media
  4. Fan system
  5. Ambient air in
  6. Water collection basin
  7. Cold water out
  8. Warm saturated air out
  9. Drift eliminators


  • Lower cooling water temperatures: The amount of evaporation – and hence heat transfer – depends on the wet bulb temperature of the ambient air which, in summer especially, is far lower than the equivalent dry bulb temperature. For example, during hot summer days with dry bulb temperatures exceeding 40°C, evaporative cooling can cool water down as far as 25°C.
  • Because evaporation removes more heat than by standard sensible heat transfer, four times less airflow is used compared to conventional air-cooled methods for heat transfer, saving considerable energy.
  • The Eurovent study provides you with clear insights on the energy saving potential of water-cooled chillers. Read here

Evaporation of water

Evaporative cooling is accomplished by the evaporation of a small portion of water. The evaporation heat is withdrawn from the remaining water or the heat exchange surface depending on the design principle of the wet cooling tower. Read the Eurovent recommendations on how to evaluate and minimise water consumption in evaporative cooling equipment.

Evaporative cooling products

Various types of evaporative cooling products exist, all featuring:

  • a heat exchange or transfer section made constantly wetted via a water spray arrangement,
  • a fan system to force or induce ambient air via the heat exchange section
  • other auxiliary components such as a water collection sump, drift eliminators and controls.

BAC offers the following evaporative cooling technology products:

Evaporative cooling equipment is marketed in a range of sizes, from compact units that are transportable fully assembled up to huge units requiring on-site construction or assembly.
A choice of many construction materials and fan arrangements allow the designer to optimally combine performance, energy usage and service life to suit each particular application. 

Want to know if evaporative cooling can help you with the heat rejection of your system? Contact your local BAC representative for more information.