Wort Cooling process is also called wort chilling. From the physical point of view, cooling is an easy process. In practice, however, breweries can choose different ways of heat transfer using either a single-stage (chilled water only) or multiple-stage (ambient water, glycol) plate heat exchangers. Wort enters the heat exchanger at between 96 and 99°C and exits cooled to pitching temperature.
The cooling operation can be achieved with a single-stage system using a glycol-jacketed cold-water tank to cool the wort.
In a two-stage system the first stage utilizes water to remove the bulk of the heat, cooling the incoming wort to within 3°C of fermentation temperature. In the second stage, the wort is cooled to the fermentation temperature by a secondary refrigerant (e.g., glycol, ammonia, etc).