Gravity coils are the most appropriate equipment for refrigerating meat, vegetables, beverages, medicines, chemical products, wines, cheeses, etc., preserving the best relative humidity conditions for such products. Among the most common types of gravity coils are freon gravity coils and glycol gravity coils.
What are gravity coils?
If you are not very familiar with the world of refrigeration, you may be wondering what these refrigeration equipment are by reading these lines. Based on the way in which heat transfer is carried out, refrigeration evaporators are classified as static and by forced air recirculation.
Gravity coils perform cooling by natural convection of the air contained in the refrigeration chamber. However, forced air recirculation evaporators use a fan to create an air current between the refrigeration chamber and the evaporator itself. For this reason, these evaporators cool food much faster than static ones, but they have the drawback of drying out the food.
For refrigeration applications with temperatures between 5 and 0 °C, gravity coils are highly recommended.
Freon Gravity Coils
Freon is one of the most used refrigerant gases in both commercial refrigeration and industrial refrigeration. The term freon encompasses a wide variety of gases, such as CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons) and HFCs (hydrofluorocarbons). If we use the ASHRAE standard, we can find the following freon refrigerant gases: R 438A, R-22, R-422B, R-410A, R-134a, R-407A, R-402B, R-402A, R-408A, R-422C, R-124, etc.
In freon refrigeration, gravity coils are cooled by said gas, which circulates inside the pipes that make up the evaporator. Freon gases, although they are excellent refrigerants and have low toxicity, are harmful to the ozone layer in the atmosphere. For this reason, its use in the world is becoming more restricted every day and other alternatives are being used.
Freon refrigeration evaporators are considered direct refrigeration equipment. That is, in these units the refrigerant is conducted directly to the evaporator, to perform the cooling function.
Glycol Gravity Coils
Glycol is not a coolant, but rather an additive that is added to water to lower the freezing point of the water. Glycol is a broad term that includes ethylene glycol and propylene glycol. The latter is the least toxic, although both have very low levels of toxicity.
A 10% water and glycol solution lowers the freezing point of water to -3°C. With a concentration of 20% glycol, water happens to have a freezing point of -8 °C. If the glycol concentration is brought to 30%, the water drops to a freezing point of -14°C. At a concentration of 40% glycol, the water drops to an even lower freezing point (-22°C). As you can see, without the glycol the water would freeze and would not be able to circulate through the evaporator or cool the chiller.
It is recommended to use distilled or demineralized water, in order to avoid the formation of deposits in the pipes of the glycol evaporators.
Glycol refrigeration evaporators are indirect refrigeration equipment. In these, the water with glycol is passed through the heat exchanger of a primary evaporator based on freon, CO2 or ammonia. Then, said water, cooled between -10 and -15 °C, is pumped to one or more static evaporators in the refrigeration chamber; Where are the meats, vegetables, wines, beers, drinks, etc.
Advantages of glycol refrigeration
In industrial refrigeration systems, as well as large commercial refrigeration, glycol refrigeration allows for to reduction of the amount of refrigerant in the system (Freon, CO2, ammonia). This is because the pipes and evaporators of the refrigeration chambers only use water with glycol, which is a cheaper and less polluting substance.
In case of accidental leaks in the evaporator, stored drinks, and food would not be contaminated. This would avoid large economic losses, in the face of such incidents.
How are static refrigeration evaporators made?
In both glycol refrigeration and freon refrigeration, the gravity coils are made up of a coil of copper tubes, mounted on an aluminum structure. To facilitate heat transfer, the structure has aluminum fins.
These evaporators have a defrost system based on electrical resistances, which periodically heat them, avoiding the excessive accumulation of ice. Meltwater falls by gravity into small trays and is led out of the cooling chamber.
Intersam: company specialized in industrial and commercial refrigeration
For almost three decades, at Intersam we have dedicated ourselves to the design and construction of commercial and industrial refrigeration systems, fully satisfying the expectations of our customers.
We have a wide range of IES gravity coils, to suit your particular needs. If your refrigeration system is glycol or freon, at Intersam we have the right evaporator for each case, which will provide you with the highest efficiency and high durability. All the materials we use are of the highest quality and our equipment meets the highest safety standards. If you have any problem or doubt regarding your refrigeration system, do not hesitate to contact us. We offer you professional attention, as well as a definitive and cost-effective solution to any problem.