Brewery Refrigeration
Refrigeration System
Mechanical refrigeration, often referred to simply as refrigeration, is a process by which heat is removed from a location using a man-made heat-exchange system. The most widely used refrigeration cycle method is mechanical compression. It has applications in both air conditioning and commercial and industrial refrigeration.
Refrigeration Cycle
The job of the refrigeration cycle is to remove unwanted heat from one place and discharge it into another. To accomplish this, the refrigerant is pumped through a closed refrigeration system. Refrigerants, are chemical compounds (e.g., freon, ammonia, brine, or glycol) that are alternately compressed and condensed into a liquid and then permitted to expand into a vapor or gas as they are pumped through the mechanical refrigeration system to cycle.
Refrigeration Units
The wide range of terms used to determine cooling capacities can be confusing for beermakers. Some manufacturers talk about refrigeration tons, others British thermal units (Btus), kilowatt (kWs), and horsepower. While it may sound confusing, they all point to the same desired result—the ability to lower the temperature of a given volume of liquid to a specific amount or Delta within a certain amount of time. While the term ton may seem unusual, it is the term used most frequently in the business.
Sizing a Refrigeration Unit
There are various ways to estimate the size of a refrigeration system needed for a brewery. One simple rule of thumb is that 1 tonR is needed for each 1,000 cases of beer or beer to be produced. For instance, a 40,000-case brewery will require a 40 tonR refrigeration unit. Another way to estimate refrigeration needs for breweries is to use a prediction of grape delivery during the course of harvest to calculate peak fermenter refrigeration loads on each harvest day based on expected fermentation kinetics.
Direct Expansion versus Secondary Loop System
In designing the refrigeration system, the brewer can either choose a primary refrigerant system, often referred to as direct expansion, or a secondary refrigerant system. Primary refrigeration systems always have lower power requirements than secondary refrigeration systems. Secondary refrigerants are liquids (e.g., glycol, brine) cooled by a primary refrigerant, and which absorb heat from the product without a change in phase.
Direct Primary Refrigeration System
As already noted, direct expansion relies on the refrigerant undergoing a change of state from a liquid to a vapor as it moves through the evaporator. The most efficient system with the greatest cooling effect for a given power input is achieved by cooling the product directly with an evaporating refrigerant—freon or ammonia. Freon is generally is generally used in smaller units and ammonia in larger units.
Secondary Refrigerant System
A secondary refrigeration system is made up of 2 sub-systems. Stage 1 of the system is a direct expansion system which chills the coolant utilized in stage 2 of the process. The coolant can either be water or a mixture of water/glycol or brine which absorbs heat through the heat exchangers. These solutions have high heat removal and retention properties, are less prone to leaks than refrigerant gases, are nontoxic in the event of unintended mixing with brewery products, are relatively easy to control, and can be held at a temperature that prevents unwanted freezing of beer on heat transfer surfaces.
Click on the following topics for more information on brewery refrigeration.
