The influence of the change of suction pressure on the refrigeration system


The influence of the change of suction pressure on the refrigeration system

When the refrigeration system is running, its suction pressure has a close relationship with the condensing temperature and the circulating amount of refrigerant.



For systems that use capillary tubes for throttling, the suction pressure is related to condensing pressure, refrigerant quantity, compressor efficiency, and cooling load. Therefore, when checking the refrigeration system, a pressure gauge should be installed in the suction pipe section. Reading the suction pressure provides an important basis for analyzing faults.


Factors of low suction pressure.

The suction pressure is lower than the normal value due to the following factors: small amount of refrigerant, small cooling load, low condensing pressure and poor filter flow. The above factors will reduce the circulation flow of the system, and the heat load of the condenser will be correspondingly reduced, so that the condensation pressure will drop. And the compressor has insufficient displacement, it must adjust the compression ratio (increase) to make up for the contradiction of insufficient displacement. Only by correspondingly reducing its suction pressure can the current compression ratio be met.


Factors of low high pressure.

The suction pressure is higher than the normal value due to factors such as high refrigerant charge, large refrigeration load, high condensing pressure and poor compressor efficiency. The above factors will increase the circulation of the system, increase the heat load of condensation, and increase the condensation pressure. If the compressor’s displacement is too large, the compressor will adjust the compression ratio (decrease) to make up for the contradiction of excessive displacement. As a result, the suction pressure can only be increased accordingly to meet the current compression ratio.




Related article: The effect of changes in exhaust pressure (condensing pressure) on the system. 

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