Advanced Mechanical Engineering

Glycol Chillers Working Principle

Glycol Chillers

Glycol chillers are one of the many refrigeration systems we can currently find in the market. As the name suggests, this type of chillers base their operation in the use of glycol. But before we learn how they work, let’s understand why glycol.

What is glycol?

Glycol is a translucid and slightly thick chemical compound with a very low volatility at room temperature, although it may exist in the air as vapor. It is used in refrigeration systems as an eco-friendly alternative for the fluorinated gases which have a great impact on the environment.

Glycol is used as a secondary fluid for refrigeration in what is known indirect refrigeration systems. The main reason is that its properties make it a better option than any other refrigerant to get in contact with the environment and any kind of food or beverages, thus being the food industry one of the main applications for glycol refrigeration systems when using USP grade glycol.

How do glycol chillers work?

To better understand how glycol chillers work, let’s divide them into two parts: the conditioning system and the glycol system.

The conditioning system involves the usual refrigeration parts we find in typical refrigeration systems, meaning a compressor, an evaporator fan and a thermostatic control to make sure the temperature reaches the desire levels. Here, different means of refrigeration can be used depending on the capacity of the chiller. The most common are cooling refrigerants such as the R-type coolants, which are used to keep the glycol at the desired temperature levels.

The glycol system usually includes a reservoir tank with a copper coil. In the tank the glycol is kept cool as the refrigeration system sends the coolant through the copper coil. A pump is attached to the glycol system which is used to pump the cold glycol to the process that requires refrigeration. Another important part of the glycol system in a glycol chiller is the return line, which consists of another copper coil to recirculate the warm glycol and cool it off in the tank before it is reintroduced into the cooling process.

As we can see, the glycol refrigeration occurs separately from the typical compressor-evaporator system, which is why glycol chillers are commonly called indirect refrigeration systems.

Working Principles of Glycol Chillers

Main applications

As it was mentioned before, USP or food grade glycol chillers are commonly used in the refrigeration processes that are required in the food and beverage industry. So, the main applications for glycol chillers include, but are not limited to:

  • Beer fermentation and other brewing processes.
  • Wine production.
  • Food production.
  • Food and beverage storage.

How Glycol Chillers Work

Final considerations

It is important to know that glycol chillers cannot always be very close to the area where refrigeration is needed, so the capacity of the chiller must cope with those distances. Also, good insulation will be required for long runs to ensure the efficiency of the heat transfer. Finally, keep in mind that, although this type of chillers do not require maintenance very frequently, eventually a technician will need to perform repairs or part replacements, so make sure there is enough space for the technician to work without the need to dismount to many elements.

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