In an open refrigeration compressor, the motor and the compressor are separated. The compressor drive shaft is connected to the motor by a coupling sleeve or by a belt and pulleys. As such you can use different types of motors (electric, diesel, gas, etc.) according to your needs.
These refrigeration compressors are therefore not known for being compact, they are mainly used for high power. The power can be adjusted in several ways:
– by stopping some cylinders on multi-piston compressors
– by changing the speed of the drive motor
– by changing the size of any pulleys
Another advatange is that all parts of the compressor are accessible for repair, unlike hermetic refrigeration compressors.
The main disadvantage of this type of refrigeration compressor is the presence of a rotating seal on the compressor shaft which can become a source of refrigerant leakage with wear.
In a hermetic refrigeration compressor, the electric motor and compressor part are enclosed in a hermetically welded envelope.
The main advantage to a hermetic refrigeration compressor is its sealing system which is ensured by the enclosed envelope and does not depend on the state of one or several joints (i.e. the rotating shaft seal for example).
But this system does not only have advantages: the cooling of the motor is ensured by the refrigerant fluid bathing the inside of the casing which heats the fluid and is detrimental to the refrigeration cycle. In principle, the cooling capacity cannot be adjusted, except by varying the frequency of the supply current.
Another disadvantage is that it is impossible to open the enclosed envelope to make any repairs and as such if something stops working the whole refrigeration compressor must be replaced. Luckily, this system is fairly affordable.
Hermetic refrigeration compressors are reserved for low and medium power requirements.
Semi-hermetic refrigeration compressors are a compromise between open and hermetic refrigeration compressors.
As in a hermetic refrigeration compressor, the motor and compressor part are enclosed in a hermetic envelope, but this envelope is not welded and all parts are accessible for repair.
The motor can be cooled by the refrigerant or, in some cases, by a liquid cooling system integrated into the casing.
The sealing system is thus better than on an open refrigeration compressor as there is no rotating seal on the transmission shaft. There are still static seals on the removable parts however and the sealing is therefore not as complete as on a hermetic refrigeration compressor.
Semi-hermetic refrigeration compressors are used for medium power requirements, and while they offer the economic advantage of being repairable, they cost significantly more than hermetic refrigeration compressors.
Piston refrigeration compressors are the most common on the market, they can be found in all configurations (open, hermetic and semi-hermetic) and for all power levels, from the lowest to the highest.
A piston refrigeration compressor needs to be constantly lubricated and is very sensitive to the presence of liquid at the inlet, which can cause the destruction of the valves.
Compared to other technology, piston refrigeration compressors are more compact and affordable, but they also have the least powerful technology.
Spiral refrigeration compressors, also called scroll refrigeration compressors, are made up of two spiral-shaped rollers. One of the spirals is fixed while the other traces an eccentric and orbital movement without rotation that moves the refrigerant to the center of the spiral while reducing its volume.
The main advantage of spiral refrigeration compressors is the reduced number of parts compared to piston refrigeration compressors, which means better output. This type of compressor imposes less torque variations on its engine, which increases its reliability and it is also less sensitive to the presence of liquid at the inlet.
It is limited in power (40-50kW) but several compressors can be combined in parallel to obtain a higher level of power, reaching up to 300-400kW.
Spiral refrigeration compressors are quieter than piston ones and they are used in many air conditioning systems and modern refrigerators.
In a screw refrigeration compressor, the refrigerant is compressed by a helical screw rotating at high speed. There are two configurations: single-screw compressors and twin-screw compressors.
These refrigeration compressors give excellent output and their power range is between 20 and 1,200kW. They also have excellent product life and are extremely reliable but they must be lubricated correctly to ensure the sealing between the moving parts, to reduce noise and cool down the refrigerant.
Among their disadvantages, it can be noted that screw refrigeration compressors are more expensive and take up more space than piston refrigeration compressors.
As we all know that the refrigeration system is composed of 4 major components, that is refrigeration compressor, condenser, throttling device (capillary or thermal expansion valve or electronic expansion valve) and evaporator. They are 4 Major Refrigeration Cycle Components.
The refrigerant compressor is a kind of machine, compressing the low-temperature and low-pressure vapor refrigerant into high-temperature and high-pressure vapor refrigerant. The refrigeration system compressor is one of the most important refrigeration cycle components. It is the core of the air-conditioning system or refrigeration system. If we compare the refrigeration cycle to the human body system, the refrigeration system compressor is one of the most important components in the refrigeration cycle. It likes heart of the vapor refrigeration system.
Refrigeration is actually achieved by changing the state of the refrigerant. The refrigeration cycle process is as bellow：
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The compressor plays the most important role in the process of changing the state of the refrigerant. It likes a pump, compresses the vapor refrigerant and increases the the refrigerant temperature and pressure, makes it flowing in the refrigeration cycle.
The compressor function in refrigeration system is as bellow:
It can be seen that the compressor plays a very important role in refrigeration cycle. So the quality of the refrigerant compressor directly affects the quality of the refrigeration system.
The function of compressors in refrigeration system and air conditioning systems is exactly the same. But due to different temperature and cooling capacity requirements, the working conditions and cooling capacity of the refrigeration system compressors are different.
There are 4 types of refrigeration compressor mainly used in commercial refrigeration and industrial refrigeration. They are reciprocating rotary compressors, rotary vane compressors, scroll compressors and rotary screw compressors. All of these compressors are belong to positive displacement compressor.
The positive displacement compressor is a kind of compressor that has the compression chamber, through the change the internal volume of the compression chamber to increase the refrigerant pressure. The positive displacement compressor often used in air conditioning, commercial refrigeration and industrial refrigeration.
In Refrigeration System, reciprocating compressors can be divided into -semi-hermetic reciprocating compressor and hermetic reciprocating compressor according to the structure.
Semi-hermetic piston compressors are widely used in cold storage refrigeration. They have the features below:
Main brands of semi-hermetic reciprocating compressors include Bitzer, Emerson Copeland, Dorin, GEA Blog, Frascold and others.
Hermetic reciprocating compressor, also called refrigerator compressor, because 90% of hermetic piston compressors are mainly used in home refrigerators and freezers. They are widely used in household refrigerators, freezers and light commercial refrigeration equipment.
Hermetic piston compressor features compact structure, good sealing, easy to use, low vibration, low noise. In the occasions with cooling capacity below 1HP, it is basically full market for hermetic piston compressors.
Rotary vane compressor widely used in home air conditioner, commercial air condition, dehumidifier, heat pump air conditioner, clothes dryer, water chiller, etc. But rotary vane compressor also widely used in commercial refrigeration and transport refrigeration. According to different installation, there are Horizontal Rotary Compressor and Vertical Rotary Compressor in refrigeration system.
Horizontal rotary compressor is specially designed for low height and compact size. Because of the low height and compact size, they are widely used in RV air conditioner, rooftop ac unit, commercial rooftop dehumidifier and water source heat pump, etc. They have the features:
R410A Inverter Rotary Compressor for Air Conditioner
R32 Inverter Rotary Compressor for Air Conditioner
R290 Inverter Rotary Compressor for Air Conditioner
In addition, the rotary compressor also widely used in commercial refrigeration. Its low height and compact size make the rotary refrigeration compressors high desirable in commercial refrigeration applications.
Features:
R404A Rotary Refrigeration Compressor (Non-Inverter)
R404A Rotary Refrigeration Compressor (Inverter)
R290 Rotary Refrigeration Compressor (Inverter)
Scroll compressors are mainly used in household air conditioners, multi-split units, modular units, small water-to-ground source heat pumps, commercial refrigeration, cold storage refrigeration.
Screw compressor is a kind of positive displacement compressor. They are widely used in central air-conditioning systems in residential and commercial buildings, In addition, screw refrigeration compressors are also used in industrial refrigeration, food freezing, cold storage, and refrigeration devices for various transportation vehicles.
If you need any help choosing the right compressor for your refrigeration system, free free to contact Glen Refrigeration team by or , we are ready to help.
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If you are looking for more details, kindly visit refrigeration compressor manufacturers.