After separation of hot trub the wort temperature is lowered to the required pitching temperature. From the physical point of view, cooling is an easy process. In practice, however, breweries can choose different methods of heat transfer.
Economical cooling in one stage
Single-stage wort cooling with pre-cooled brewing water is considered as state-of-the-art. With this type of wort cooling the wort is cooled to the pitching temperature in one pass. So all the heat used is returned to the brewing process. Depending on the number of brews per day, the brewing water is pre-cooled continuously or at certain times using low electricity tariffs. Pre-cooling of brewing water is performed with cooling brine, alcohol-water mixture or by direct evaporation of the refrigerant. Besides brewing liquor cooling we can also offer two alternative systems: The water storage system is recommended when operated with direct evaporation. Direct evaporation is preferable for a high number of brews per day. In this case continuous cooling without storage is necessary. Of course, this is done fully automatically - and very effectively at high evaporation temperatures - in a semi or fully welded plate and frame evaporator. However, to manage energy and water surplus two-stage wort cooling was common practice. In the first stage of the plate and frame heat exchanger, part of the thermal energy of the wort was transferred to the brewing water. In this way preheated brewing water was made available for the next brew. In the second stage, chilled water, cooling brines, alcohol-water mixtures or direct evaporation of the refrigerant were used to lower the temperature of the wort to pitching temperature.
