Lesson 8 - Refrigeration Technology
This lesson takes a closer look at refrigeration technology. It reviews the different primary and secondary refrigerants and explores the technology required to deliver primary refrigeration to the brewery. It concludes by looking at how refrigeration is used within the brewery.
Common Primary Refrigerants in Breweries
This section will describe the two most commonly used primary refrigerants in brewing: ammonia and carbon dioxide.
Ammonia (R717)
Ammonia (R717) is widely used in the brewing industry for a number of reasons.
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It is environmentally friendly.
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It is classified as highly toxic but only in high concentrations, and the same applies to its flammability.
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Ammonia gas is non-flammable, but because it can be explosive at certain concentrations (15-28%) when mixed with air, it is classed as flammable.
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It stinks! This is good, because it helps us to detect the source of a leak using our sense of smell. Some people can smell ammonia at 0.6 mg/L.
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It is highly water soluble and can be easily removed immediately from the air using a water spray, should a leak develop. Note: Ammonia even in low concentrations is toxic to aquatic life. Measures are therefore required to prevent release of aqueous ammonia solutions to watercourses.
A secondary refrigerant is often used so that the ammonia can be contained within an area. The areas where ammonia is present must be well-ventilated. Ammonia gas detectors and alarms can be installed and all personnel must be trained on the safety and emergency aspects of working with ammonia.
Having said this, ammonia is still a good refrigerant because of the desirable pressures and temperatures at which it operates, as well as the relatively high COP achieved as a result of this.
One of the first ammonia systems used in a brewery was installed as early as 1876, enabling a Bavarian brewery to produce beer throughout the year.
Carbon dioxide (R744)
Carbon dioxide (R744) was used almost exclusively as refrigeration on board ships transporting meat and other perishable cargos. This was because ammonia was too potentially dangerous. Carbon dioxide is now making a comeback in breweries due to its environmental and safety benefits. Its biggest disadvantage is that it operates at high pressures (even on the low pressure side of the circuit), which means that it requires equipment that can withstand the pressure. In brewing, it can be used in a cascade system with ammonia. We will mention cascade systems a little later on in the lesson.
Future options
R723 is a natural refrigerant, which is a blend containing ammonia. It has been proposed as an option for the future as it has the potential to provide a better COP, however, it is not yet commonly used.
For more information on R723 read:
https://www.ammonia21.com/knowledge/papersView/what_is_r723. Note, this is for illustrative purposes only and is not a recommendation or endorsement of the supplier's product.