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You are here : Home > Services > FROZY’s advice > Selection of a suction line accumulator
Selection of a suction line accumulator

Role and selection of a suction line accumulator

The purpose of the suction line accumulator is to protect the compressor against an accidental return of refrigerant in its liquid phase, by the suction pipes, which could cause a “liquid hammer” with a risk of mechanical destruction of the compressor. The same problems can be generated by an oil compression, as result of a sudden flow at the compressor suction, because of oil corks located in the evaporator or the pipes.

This suction accumulator ensures the refrigerant re evaporation and suction by the compressor, and the return of the oil trapped in the lower part of the accumulator as well. These models are LCY and LCYE series of CARLY.
The liquid refrigerant falls down in the accumulator and is vaporized by external heat addition; the accumulator has an internal suction stick pierced in the lower part. When it goes through this small hole, the refrigerant expands, is then vaporized and finally sucked in by the compressor; the oil that remained liquid is sucked in with the refrigerant through this hole as well.

It is possible to improve this re evaporation of the refrigerant by adding a heat exchanger in the suction accumulator (CARLY LCYE models only). This improves the subcooling, reduces the risks of pre expansion of the refrigerant and it improves substantially the efficiency of the installation. The internal exchanger of the LCYE must be connected to the liquid line (after the receiver) of the installation. It must not be connected to the discharge line because there would be a risk to create a overheating at the level of the compressors.

CARLY suction line accumulators

 

 

 

Opening for expansion and oil return

 


With heat exchanger: LCYE------ Without heat exchanger : LCY

 

The suction accumulator has to be installed in a vertical position, as closed to the compressor as possible, and at the same height if possible.

 

The selection of a suction accumulator depends on the refrigeration capacity of the installation, the type and the quantity of refrigerant, and the evaporation temperature; it does not depend only on the diameter of the suction pipe.

In order to avoid additional pressure drops, the refrigeration capacity of the installation must not be superior to the maximal capacity acceptable by the suction accumulator. And in order to avoid oil return to the compressor, it must not be inferior to its minimal capacity.

Besides, the capacity of the selected suction accumulator in kg of refrigerant at 30°C must be superior to the half of the total load of refrigerant of the installation.

 

Example of selection:
  • Installation operating with R404A under the following conditions:
  • To = -10° C
  • Tk = 30° C
  • Qox = 8kW
  • Capacity of refrigerant at 30°C of the circuit = 5 Kg
  • Suction piping: 7/8".
  • Which LCY suction line accumulator to choose?
  • LCY model selection in function of the installation refrigerating capacity:
    • "MAXIMUM refrigerating capacity" selection curves for R 404A hereafter:
      • Qox = 8 kW and To = -10° C, Result: LCY 27 S or LCY 47 S
    • "MINIMUM refrigerating capacity" selection curves for R 404A hereafter:
      • Models chosen: LCY 27 S or LCY 47 S, result: 2 kW < 8 kW; the selection is correct.

 


 

 

  • LCY Volume Selection Using The Installation Refrigerant Load:
  • Selection table hereafter ; half the refrigerant load represents 5 / 2 = 2.5 Kg
  • LCY 27 S : 1.8 Kg and LCY 47 S : 2.6 Kg, result : LCY 47 S


Nota:
The sizing of a product implies for the buyer to take into account the conditions under which the product will be used (temperature, pressure, refrigerant, oil, external environment) and to make a prior technical validation.

 

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