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Screw refrigeration compressor and piston refrigeration compressor are not clearly separated? It is good to distinguish this way

Date:Jan 08, 2020

[China Refrigeration Network] Distinguishing from Types


Screw refrigeration compressor and piston refrigeration compressor belong to positive displacement compressor, and screw refrigeration compressor is a new type of high speed refrigeration compressor.


Screw refrigeration compressor and piston refrigeration compressor are not clearly separated?  It is good to distinguish this way.


Distinguish in principle


Judging from the principle of compressing gas, the two compressors have in common that the gas is compressed by the change of volume.  The difference is that the two types of compressors have different ways to realize the change of working volume.  The piston refrigeration compressor changes the working volume of the cylinder by means of the movement of the crankshaft connecting rod mechanism.  Screw refrigeration compressor changes its working volume by means of the rotary motion of the rotor directly connected to the shaft.


Distinguish from the overall structure


Screw refrigeration compressor has no cylinder, piston, piston ring, cylinder sleeve and other vulnerable parts required by piston refrigeration compressor. The machine has compact structure, small volume, light weight, no clearance volume, and no liquid strike danger when a small amount of liquid enters the machine.  The valve can be used for 10% ~ 100% stepless energy regulation, with wide application range, stable and reliable operation, long maintenance period, and trouble-free operation time up to (2 ~ 5) × 104 h.  Due to the use of lubricating oil, the cooling and sealing performance of the machine is improved, and the exhaust temperature is reduced. Even if the evaporation temperature is lower (-40℃) and the compression ratio is higher (about 25), the machine can still operate in a single stage, i.e. it can replace the two-stage compression cycle within a certain range.  However, the processing and assembly of screw refrigeration compressor requires high precision, is not suitable for off-design operation, and has relatively large noise. Under normal circumstances, sound attenuation and sound insulation equipment shall be installed. During refrigeration and compression, lubricating oil shall be sprayed, thus requiring more auxiliary equipment such as oil pump, oil cooler and oil retriever.


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