What is a Compressor in a Refrigeration System?
A compressor is the most critical component in a refrigeration and air conditioning system, as it is responsible for driving the entire refrigeration cycle.
To understand the role of a compressor, we need to know what a refrigeration system is.
A refrigeration cycle usually runs through four key parts: the evaporator, compressor, condenser, and expansion device.
In the evaporator, the refrigerant soaks up heat and changes into a low-pressure vapor.
This is where the compressor comes in. It takes in the low-pressure vapor and squeezes it into a high-pressure, high-temperature gas.
This boost in pressure and temperature gives the refrigerant enough energy to let go of the heat it absorbed when it reaches the condenser.
A compressor ensures efficient energy use by maintaining the proper temperature and pressure conditions.
Learn about the refrigeration cycle and the components required for a refrigeration system through videos.
What are the 5 Types Of Compressors in a Refrigeration System?
Understanding the type of compressor is necessary to understand the best-suited compressor for your application, whether it is for residential air conditioners or large-scale cold storage facilities.
According to the working principle of the compressor, it can be divided into
- Scroll Compressor: This compressor is widely used in HVAC systems, commercial chillers, heat pumps, and cold rooms. It is known for quiet operation, compact design, and higher energy efficiency. It has smooth compression, which is ideal for continuous duty applications in both cooling and heating systems, particularly where temperature stability is critical.
- Rotary Compressor: This compressor is most commonly found in residential split air conditioners and small-scale dehumidifiers. This Rotary compressor is a popular choice in household HVAC units, where space and cost efficiency are top priorities. It operates smoothly and is best suited for moderate cooling loads.
- Piston Compressor: Piston or Reciprocating Compressor is ideal for walk-in coolers, freezers, and commercial refrigeration units. It works by using a piston-cylinder mechanism to compress refrigerant. They are durable, serviceable, and highly effective in intermittent operation environments such as restaurant cold storage or grocery refrigeration systems.
- Screw Compressor: This screw compressor is used extensively in industrial refrigeration, large cold rooms, and processing plants. It delivers continuous, high-volume air flow. It has fewer moving parts and lower vibration, which offers excellent reliability for heavy-duty applications.
- Reciprocating Compressor: This compressor is often used interchangeably with piston compressors, but is commonly found in refrigerators, home freezers, and small chest coolers. Its design is simple, which makes it widely adopted in domestic refrigeration systems where cost and efficiency are significant factors.
According to the compressor structure, it can be divided into
- Hermetic Compressor: This type of compressor is fully sealed within a welded steel shell, and it is commonly used in household refrigerators and small AC systems. They are compact, quiet, and maintenance-free, but not serviceable.
- Semi-hermetic Compressor: This type of compressor is found in cold storage, commercial HVAC, and industrial freezers, enclosed but also can be opened for repairs. They offer a balance between reliability and maintainability.
- Open Compressor: This type of compressor is used in large-scale refrigeration plants and marine refrigeration. These compressors have a shaft extending outside the housing, driven by external motors. They require more maintenance but offer high power and flexibility.
According to the control method, it can be divided into
- Variable Frequency Compressor: This type is also called an inverter-type compressor, which automatically adjusts its speed based on cooling demand, offering superior energy efficiency. Common in modern HVAC systems, heat pumps, and smart AC units.
- Fixed Frequency Compressor: This type of compressor runs at a constant speed, and it is ideal for basic cooling systems where load variation is minimal.
According to the Application, it can be divided into
- Cold room compressor
- Walk-in cooler compressor
- Walk-in freezer compressor
- Commercial refrigeration compressor
- Industrial refrigeration compressors
Check out our Types of Compressors Guide or talk to our team for expert advice.
How Does a Refrigeration Compressor Work?
Before understanding how a compressor works, it’s important to first understand its main components:
The intake valve plate, the exhaust valve plate, the piston (scroll, rotor, screw), the connecting rod, the crankshaft, and the motor.
A refrigeration compressor operates in three basic steps: suction, compression, and exhaust, which occur continuously.
Let’s use a semi-hermetic piston compressor as an example. The operating principles of scroll, rotor, and screw compressors are similar to those of piston compressors.
When the compressor is powered on, the motor drives the crankshaft, which in turn drives the connecting rod, which in turn drives the piston.
Intake(suction): When the piston reaches bottom dead center in the cylinder, negative pressure is generated, allowing space for the refrigerant to enter.
Compression: Driven by the motor, the piston begins to move upward, compressing the refrigerant.
Exhaust: When the pressure in the compressor cylinder exceeds the force of the valve plate spring, the high-pressure gas is discharged, thus enabling the refrigerant to circulate.
What Does the Compressor Do in the Refrigeration System?
1. After understanding the working process of the refrigeration compressor, you will know that the function of the compressor is to drive the refrigerant to operate and keep the pressure of the refrigeration system within the specified range(High-pressure side 2MPa).
2. The other job of a refrigeration compressor is to boost the refrigerant vapor’s pressure and temperature so it can easily release heat in the condenser.
3. In the variable frequency compressor system, the compressor controls how much refrigerant moves through the system and keeps the pressure at the right balance.
4. Keeps the heat exchange cycle running continuously, ensuring the system works efficiently from start to finish.
5. The compressor makes sure the evaporation and condensation pressures are proper, keeps the superheat and subcooling, and influences performance parameters.
This makes it one of the most important and often the most expensive parts of any refrigeration unit.
What is the Application of a Refrigeration Compressor?
Refrigeration Compressor for Cold Rooms?
For cold rooms, semi-hermetic and screw compressors are popular choices.
Semi-hermetic compressors are reliable, repairable, and great for your medium to large setups.
Screw compressors work well for big storage facilities, offering steady cooling and high efficiency over long periods.
When choosing a compressor, consider your cold room size, target temperature, cooling load, and budget.
The right compressor not only keeps your products fresh but also saves energy and reduces long-term costs.
Check Cold Room- A Complete Guide to know why the semi-hermetic compressor is right.
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- Refrigeration compressor for meat cold storage
- Refrigeration compressor for seafood cold storage
- Refrigeration compressor for dairy cold storage
- Refrigeration compressor for mushroom cold storage
- Refrigeration compressor for potato cold storage
- Refrigeration compressor for fruits and vegetables cold storage
Refrigeration Compressor for Walk-in Cooler/Freezer
For a walk-in cooler/freezer, scroll compressors are a better choice, such as those made by Copeland. Danfoss, Invotech, etc.
Its advantages are low noise, low vibration, and easy movement, and it can provide reliable services for mobile walk-in coolers, kitchen walk-in coolers, and hotel walk-in coolers.
Check Walk-in Cooler- A Complete Guide to know why the semi-hermetic compressor is right.
Refrigeration Compressor for Plug-in Commercial Refrigeration
For a plug-in commercial refrigeration, a reciprocating piston is the best choice, such as Secop, Embraco, Tecumesh, and Maneurop compressors, etc.
The advantages of a reciprocating piston compressor are small size, light weight, and an obvious cost advantage.
Types of Compressors in Refrigeration PDF
Miracle has 30 years of experience in refrigeration unit manufacturing. We represent brands including Bitzer, Copeland, Danfoss, Frascold, and Carrier.
If you need refrigeration compressors for your refrigeration units, cold storage units, heat pump units, chillers, transport refrigeration units, or rail transit units, Miracle is your reliable partner.
Please check the Miracle refrigeration compressor PDF now.
Top Refrigeration Compressor Manufacturers
Refrigeration compressors are primarily manufactured in the United States, Germany, Denmark, China, Thailand, and Japan.
China has the largest demand and production of compressors.
Miracle, as a Chinese manufacturer of semi-hermetic and screw compressors, provides you with the most cost-effective compressor options.
We list a refrigeration compressor manufacturer, hoping to help find the right compressor.
Scroll compressor manufacturers’ list
Piston/screw manufacturers’ list
- Bitzer compressor-piston/screw compressor
- Frascold compressor-piston/screw compressor
- Refcomp compressor-piston/screw compressor
- Carlyle compressor-piston/screw compressor
- Dorin compressor-piston/screw compressor
- Bock compressor-piston compressor
- Miracle piston compressor
- Miracle screw compressor
If you’re unsure about which type or brands suit your system, check out our guide on how to choose the right compressor or contact Miracle directly.