In industrial refrigeration systems, condenser and evaporator coils are responsible for directly carrying out the heat exchange process. This heat exchange is essential for the proper functioning of the cooling system and also for reducing its energy consumption. As a result, condenser and evaporator coils serve as the heat exchangers in industrial, commercial, and domestic refrigeration systems.

What are condenser and evaporator coils?

Condenser and evaporator coils are rectangular-shaped structures composed of groups of copper, aluminum, or stainless-steel tubes. These tubes are supported and arranged in parallel by a frame, which provides the necessary rigidity and robustness. Inside the tubes, various refrigerant gases flow, depending on the type of industrial or commercial refrigeration system.

How are they constructed?

The construction geometry of condenser and evaporator coils depends on their intended location. There are differences in their design if they are meant for a ceiling-mounted, wall-mounted, or cubical evaporator, for example.

Copper is typically the preferred material for the tubes due to its thermal conductivity of 398 W/m × °K. Aluminum is used as the second material with a thermal conductivity of 247 W/m × °K. Finally, stainless-steel tubes, with a thermal conductivity of 30 W/m × °K, are also employed.

For ammonia refrigeration systems (NH3), which chemically attack copper and aluminum, the coils should be constructed using stainless steel. On the other hand, when dealing with refrigerants like CO2, special attention must be given to the high working pressures in these systems.

Regarding the tube diameters, the most commonly used sizes in industrial refrigeration systems are 1/2 and 5/8 inches. Additionally, depending on the working pressure, tube thicknesses can range from 0.3 mm to 1.2 mm. To improve the thermal exchange efficiency between the refrigerant gases and the air, the tubes have externally inserted fins made of aluminum, steel, or copper. The spacing between the fins is a critical factor, varying between 2 mm and 12 mm.

The frames and crosspieces that shape the coils and support the tubes are made of galvanized steel or aluminum alloy. The entire structure is firmly connected using rivets. As for the copper tubes, they are soldered using phosphorus copper and silver alloy. For stainless-steel tubes, TIG welding with inert gas is used for the joints.

Functions of the coils on the heat rejection side

After leaving the compressor, the refrigerant gases are at high pressure and temperature. These gases enter the condenser coils to be cooled and condensed. Consequently, at the outlet of the coils, the refrigerant should be in a liquid state and slightly subcooled. If the coils fail to transfer the heat of the refrigerant to the forced air generated by the fans, the condensation process won’t be complete, leading to negative consequences for the system.

Functions of the coils on the cold side of industrial refrigeration systems

The coils in cold storage chambers facilitate the evaporation of the liquid refrigerant that enters them. This refrigerant enters the coils at a low temperature as it comes from the thermostatic expansion valve outlet. Consequently, the forced air from the fans quickly cools down as it passes through the coil fins. This cold air is ultimately responsible for cooling the meats, fruits, beverages, etc. At the outlet of the evaporator, it is crucial that all the refrigerant has completely changed to a gaseous state. This way, these refrigerant gases can be suctioned by the compressor without causing any damage.

Maintenance of condenser and evaporator coils

Regular cleaning and preventive maintenance of condenser and evaporator coils are essential tasks in any system. Without proper maintenance, the coils may lose their efficiency and fail to perform their functions adequately. Therefore, these coils must be designed to be easily assembled and disassembled. It is essential for the coils not to be excessively heavy while still maintaining durability.

Are you unsure about the efficiency of the coils in your refrigeration system?

Although the design of the refrigeration system may have been highly technical and meticulous, the final installation might have some differences in practice. This can be due to various factors, including economic constraints, technical issues, unforeseen errors, etc. Hence, concepts like design capacity and actual capacity might be discussed. Additionally, it’s possible that a coil’s performance falls short or exceeds the system’s requirements. Furthermore, every piece of equipment has a limited lifespan and should be replaced at the end of its useful life to avoid frequent failures.

If you encounter any issues with the condenser and evaporator coils in your system, you can rely on Intersam. At Intersam, we specialize in designing and manufacturing industrial coil systems for synthetic refrigerants, ammonia, CO2, propane, and more. Our equipment is built with the highest quality materials and adheres to the most stringent regulations. Should you encounter any inconveniences, do not hesitate to contact us.

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