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Wort Cooling
Wort Cooling Systems
After boiling and clarification, the wort leaving the whirlpool has to be cooled in preparation for the addition of yeast and subsequent fermentation. Wort is usually cooled through plate heat exchangers (Figure 12.1). Heat exchangers are of two types: single-stage (chilled water only) or multiple-stage (ambient water, glycol). Wort enters the heat exchanger at approximately 96 to 99ºC and exits cooled to pitching temperature. The energy requirement is less with two-stage cooling than with one-stage cooling (9). The first stage utilizes water to remove the bulk of the heat, cooling the incoming water to within 3ºC of fermentation temperature. In the second stage, the wort is cooled to the fermentation temperature by a secondary refrigerant, e.g., glycol. Some craft brewers, in an attempt to reduce capital expenditures, will use the same glycol system that provides the cooling for the fermentation. Most small brewers would prefer two-stage cooling but use one-stage cooling to save money. Alternatively, the cooling operation can be achieved in a single stage using a glycol-jacketed cold water tank to cool the water to approximately 3ºC below that of the required wort temperature (5). In both systems, the heat from the wort is transferred to the water. That water can then be used for other purposes, but mainly as a source of warm brewing water.
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