Fundamentals of Commercial Refrigeration Systems
Commercial refrigeration is a critical part of your business and building operations and can easily be impacted by downtime or failure if routine maintenance is overlooked. Whether you operate a skyscraper, grocery store, restaurant, or any other type of business that relies on refrigerated items, it’s important to understand the basics of commercial refrigeration systems. This blog post will outline the four types of commercial refrigeration systems. Stay tuned for more information or contact our red seal refrigeration technicians.
Working on a Commercial Refrigeration System
Commercial refrigeration systems are typically an arrangement of mechanical components to provide cooling capacity. System chillers or air conditioners will utilize heat exchangers and circulate gas to cool the air passing through the unit.
The chiller units are usually located in a mechanical room, area, or they can be located in a central plant facility for chillers. They will cool air by removing heat using a refrigeration or vapor compression cycle that consists of compression condensation expansion and evaporation.
Components of the Refrigeration Cycle
The main components of the refrigeration cycle are the compressor, the condenser, liquid receiver, the evaporator, and there are also control devices that provide the chilling component of an air handling system.
Basic Fundamentals of a Refrigeration System
To review the fundamentals of the refrigeration system, here are complete details.
Vapor Formation and Heat Behavior
Vapor formation is the first fundamental. The first refrigerant is compressed in the compressor reducing its volume increasing its temperature. It’s pumped to a condensing unit where the refrigerant is cooled and condensed into a liquid; the liquid is then pumped to the indoor evaporator unit.
It is passed through the evaporator coils that will remove heat from the building; the hot air in the building is passed over the evaporator coils.
As a result, heat is added to the refrigerant and removed from the air. The air is then recirculated back to the building; the heat added to the refrigerant turns it into a vapor, and then it’s sent back to the compressor to repeat the cycle.
Chiller condensers remove heat from a system by cooling the air stream, leading to cooling water and evaporation.
Air Cooled Systems/Convection Transfer of Heat
Air-cooled systems are frequently used in commercial buildings where the cooling load is less than a hundred tons of refrigeration.
The air-cooled condenser comprises coils containing the flowing refrigerant and provides a large surface area for convection transfer of heat and forced air through a fan unit. This convection removes heat from the refrigerant and completely removes it from the system.
Water Cooled Systems
Water-cooled systems are used for commercial buildings that have larger cooling loads. They also have higher efficiency than the air-cooled system. In these systems, water is used to remove heat from the refrigerant flow instead of air, so with the heat removed, it’s pumped to a cooling tower where the heat is rejected to the atmosphere, and the water is pumped back to the condenser.
Cooling towers reject heat through air streams to evaporate a portion of the incoming water then the rest of the incoming water is cooled. But heat transferred to the air causes a rise in the air, and it flows out through the top of the tower and into the atmosphere.
Water-cooled chillers have higher efficiencies when compared to air-cooled chillers as a general rule, as such this is due to how they reject heat at the wet-bulb temperature rather than the dry-bulb temperature.
Water-cooled chillers are smaller in size than most air-cooled chillers, with the same cooling capacity that’s new to the condenser requiring less surface area, and it also operates without fans; the noise level is also much lower.
Evaporative Condensing / Evaporative Cooling
Evaporative condensing refrigerators operate basically as a more efficient water-cooled system, except they use evaporative cooling provided by the cooling tower. The cooling is accomplished by a recirculating water system that continuously wets the condenser tubes while fans provide airflow over them.
This evaporates the water and rejects the heat into the atmosphere. Evaporative coolers will use much less water than water-cooled chillers, so the operational costs are lower; this slide shows a typical cooling tower for commercial building facilities for the chiller systems.
Types of Compressors and Their Technical Mechanisms in Refrigeration Systems
We’ve looked at each we’ll have one of four main types of compressors reciprocating centrifugal screw is driven or absorption reciprocating centrifugal. Screw chillers are mechanically powered by electric motors, steam power, or a gas turbine. The absorption chillers are powered by heat energy, and there are no moving parts involved.
Reciprocating compressors will utilize Pistons that are driven by crankshaft centrifugal compressors. They will use centrifugal force to compress the air in the industry due to their relatively high energy efficiency.
Screw-driven compressors used two opposing screws to compress air looking at commercial building facilities. These units are self-contained packages that include the compressor, the condenser, and the evaporator, all on the same chassis and within the same framework.
With these systems, heat is exchanged directly with the refrigerant passing through the tubes of a fin cooling coil. A split system is similar to the concept, but the evaporator is in a separate housing mounted in the space.
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