How to choose the right compressor

Choosing the right refrigeration compressor

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A cooling circuit, such as that found in heat pumps, air conditioning and cooling systems, consists of four elements: a compressor, a condenser, a pressure reducer and an evaporator. In a cycle, the role of the refrigeration compressor is to compress the refrigerant gas by applying the mechanical force required to create the refrigeration.

Cooling compressors are divided into three technology groups:


as well as three types:


Refrigeration compressors at a glance

  • How to choose a refrigeration compressor

    When choosing a refrigeration compressor, the first basic criterion is the one needed Cooling capacityas the different compressor models do not apply to the same area of ​​application. Choosing a technology is straightforward for low or very high performance needs. It looks different if you need a medium level of performance, because different models can prove to be suitable.

    That too economic criterion is crucial; For example, you have to distinguish between an inexpensive hermetic compressor, which cannot be repaired in the event of a breakdown, and a semi-hermetic or even open model, which is more expensive but can be repaired in the event of a problem. In the case of high-performance devices, you have the choice between an inexpensive reciprocating compressor or a screw compressor, which is more expensive but more energy-efficient.

    The choice can also be based on criteria like that Noise development or thatSpace requirement to be determined.

    A final, extremely important criterion is to make sure that the chosen model compatible with the refrigerant contained in the cooling circuit. The market offers numerous fluids and the manufacturers of refrigeration compressors have specially adapted models.

  • What is an open refrigeration compressor?

    In an open refrigeration compressorthe motor and compressor are separate from each other. The drive shaft of the compressor is connected to the motor by a connecting sleeve or a drive belt and corresponding pulleys. Different types of engines can be used as required (electric, diesel, gas, etc.).

    Compactness is therefore not a particular asset of refrigeration compressors, and they are mainly used for high performance used. This service can be regulated in different ways:

    - By stopping certain cylinders on multi-cylinder compressors

    - By changing the speed of the drive motor

    - By changing the size of any pulleys

    Another advantage is that, unlike hermetic compressors, all of the compressor elements accessible for repairs are.

    The main weak point of this type of compressor is the presence of a rotating sealing ring on the drive shaft which, when worn, can become a point of leakage for the refrigerant.

  • What is a Hermetic Refrigeration Compressor?

    In a hermetic refrigeration compressor, the (electric) motor and the compressor part are in one Hermetically sealed housing includedThe main advantage of a hermetic refrigeration compressor is its Tightnesswhich is guaranteed by the housing and does not depend on the condition of one or more sealing rings (e.g. the seal of the rotating shaft). However, this design has not only advantages. The engine cooling is triggered by the refrigerant inside the housing, which causes the fluid to heat up, which is disadvantageous for the cooling cycle. In principle, the cooling capacity cannot be regulated unless the frequency of the power supply is changed. Another disadvantage is the fact that in the event of a breakdown it is impossible to open the housing - the entire compressor has to be replaced. Fortunately, this construction is right inexpensive.

    Hermetic compressors are only suitable for small and medium capacities.

  • What is a Hermetic Refrigeration Compressor?

    Semi-hermetic compressors represent a compromise between open and hermetic compressors. As in a hermetic compressor, the motor and compressor days are in one hermetic housing included, but this case is not welded, and all elements are accessible for repairs.

    The motor can be cooled by the refrigerant or, in some cases, by a cooling circuit integrated in the housing.

    TheTightness is therefore better than an open compressor, thanks to the lack of a rotating sealing ring on the drive shaft. However, there are still static seals on the degradable parts. The tightness is therefore ultimately less good than with a hermetic compressor.

    Semi-hermetic compressors are used for medium power levels. They have the economic advantage of being repairable, but are significantly more expensive than the hermetic compressors.

  • Why a piston refrigeration compressor?

    The reciprocating refrigeration compressors are the most popular on the market. They can be found in all designs (open, hermetic and semi-hermetic) and in all power levels, from the smallest to the highest.

    A reciprocating compressor is a must be constantly lubricated and is extremely sensitive to the presence of liquid during suction, as this can destroy the valves.

    Compared to other technologies are reciprocating compressorsmore compact and cheaper; however, their technology is the least powerful.

  • Why a scroll refrigeration compressor?

    The scroll compressors, also known as scroll refrigeration compressors, consist of two spiral-shaped rollers. One of the spirals is stationary, the other describes an eccentric, circular movement without rotation that moves the refrigerant towards the center of the spiral, thereby reducing its volume.

    The main advantage of these compressors, compared to a reciprocating compressor, is the reduction in the number of parts that make up abetter production output makes noticeable. This type of compressor loads the engine with fewer torque variations, which means the reliability elevated. He is also less sensitive to liquid when sucking.

    Its output is limited (40-50 kW), but several compressors can be connected in parallel to achieve a higher output of up to 300-400 kW.

    Scroll compressors have one lower noise development as reciprocating compressors, and they can be found in numerous air conditioning systems and modern refrigerators.

  • Why a Scroll Refrigeration Compressor?

    In a screw refrigeration compressor, the refrigerant is compressed by a helical screw that rotates at high speed. Two configurations are offered: monorotor compressors, with one screw, and birotor compressors, with double screw.

    These compressors have oneexcellent output, and their power is between 20 and 1 200kW. You still have oneexcellent durability and reliability, but absolutely must correctly lubricatedto ensure the tightness between the moving parts, to reduce the noise level and to cool the refrigeration product.

    As for the drawbacks, it can be noted that screw type refrigeration compressors are more expensive and space consuming than reciprocating compressors.

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