Glycol coolers are one of the most widely used indirect refrigeration systems today. Glycol refrigeration is used in industrial and commercial applications as it is an environmentally friendly substance with low toxicity. In this article, we will talk in detail about industrial and commercial refrigeration with glycol and the most used types of glycol coolers.

What are indirect cooling systems?

If you are not very familiar with refrigeration, you are probably wondering what indirect refrigeration is. To understand this concept, you first have to understand what direct industrial refrigeration is. Direct refrigeration is the one that is done directly with the refrigerant gas (fluorinated, CO2, or ammonia), taking it to the cold room itself. On the other hand, indirect glycol refrigeration is one where the refrigerant gas does not go directly to the heat exchanger of the cold room. That is, the cold is transported by glycol to the cold room. But first, the glycol must be cooled by any type of refrigerant (fluorinated, CO2, or NH3), using a heat exchanger.

Why is glycol used for cooling?

To be more precise, it is not pure glycol that is used to transport cold, but a solution of distilled water and glycol. Glycol water lowers its freezing point several degrees below 0°C, depending on the glycol concentration. For example, with a concentration of 10%, the freezing point of water drops to -3 °C. But with a concentration of 30%, the freezing point of water reaches -14 °C. If we increase the concentration up to 50%, the freezing point reaches -34 °C.

Without the glycol, the water would freeze fast and be unable to flow into the cold room. Also, when the water freezes inside the pipes, they tend to burst. In glycol chillers, water typically circulates at temperatures several degrees below 0°C.

Glycol for cooling allows a reduction of the amount of refrigerant gas in commercial and industrial refrigeration systems. This is because there is no need to bring some type of refrigerant directly to the cold room, as stated above. Therefore, refrigerant expenses are reduced and the environmental impact due to their intensive use (mainly fluorinated refrigerants) is lowered.

It is important to note that the glycol water for cooling is distilled, to avoid deterioration of the pipes and the pump. In addition, the glycol water solution is extremely stable and does not degrade with use or over time.

On the other hand, there are two types of glycols: ethylene glycol and mono propylene glycol. Both have very similar antifreeze properties, but ethylene glycol is the more toxic of the two. For this reason, mono-propylene glycol is most widely used in the food, wine, beer, and pharmaceutical industries.

Types of glycol chillers

Glycol chillers are basically composed of the cold generating unit and the glycol water circuit to cool the cold room. The cold-generating unit can be classified according to the type of refrigerant used to cool the glycol. In other words, if we focus on this aspect, we can classify glycol refrigeration based on the refrigerant used. For this case, the types of glycol coolers would be fluorinated (R-134a, R-404A, R-410A, R-407C, etc.), ammonia (R-717), and CO2 (R-744).

On the other hand, when the compressor technology of the cold generating unit is taken into account, the types of glycol chillers can be screw, rotary, or piston. However, in this post, we will focus only on how heat transfer takes place in the cold room. Therefore, the types of glycol coolers can be static or forced air.

Static glycol coolers for glycol cooling of cold rooms

In many cases, these coolers are the most suitable when you need to refrigerate food, but without altering its humidity. These units are heat exchangers built with copper tubes and aluminum radiator fins. The cold glycol circulates inside the copper tubes and the heat transfer is done by natural convection of the air in the cold room.

Glycol static coolers cover only high and medium-temperature applications. These units come with electric defrost heaters and auxiliary trays to drive the water out of the cold room.

Cold Room Forced Air Glycol Coolers

When cold room air is forced through the heat exchanger, heat transfer is faster and more efficient. Forced air coolers are closed metal structures, inside which are the heat exchanger and one or more forced draft fans. This system is widely used in industrial and commercial refrigeration at high, medium, low, and very low temperatures.

The heat exchanger is also made of copper tubes with aluminum fins and has built-in electric heaters for defrosting. Depending on the design, the distribution of the exhaust cold air can be simple or double distribution. The latter provides more uniform cooling in the cold room.

Forced air coolers are normally mounted on the ceiling of the cold room. On the other hand, the fans are of the helical type, with single-phase or three-phase electrical power. To ensure that the electric motor does not stay at very low temperatures, its bearings use special low-temperature grease.

Intersam and glycol refrigeration

At Intersam we are a company with extensive experience in the design, manufacture, and installation of industrial and commercial refrigeration systems. In the wide catalog of Intersam solutions, the static glycol coolers (IES) stand out and are designed for different needs.

In addition, we offer forced-air glycol cubicle chillers for high, medium, and low-temperature commercial applications (ICAW, ICMW, ICBW, respectively). On the other hand, at Intersam we have high, medium, low, and very low temperature forced air industrial cubic coolers (ICIAW, ICIMW, ICIBW, ICITW, respectively).

We also have ceiling-mounted glycol coolers, with double air distribution. For this application, we have high, medium, low, and very low-temperature solutions (IPIAW, IPIMW, IPIBW, IPITW, respectively). If you have questions, do not hesitate to contact us.