Refrigerant control method of parallel multi-split air-conditioner

Abstract

The invention discloses a refrigerant control method of a parallel multi-split air-conditioner. The method comprises the steps of S1, in a heating mode, comparing the degree of superheat of each outdoor unit with the average degree of superheat of a plurality of outdoor units, S2, when the degree of superheat of the current outdoor unit is overhigh in contrast with the average degree of superheat, increasing the amount of the refrigerant going into the current outdoor unit, and S3, when the degree of superheat of the current outdoor unit is overlow in contrast with the average degree of superheat, reducing the amount of the refrigerant going into the current outdoor unit. In this way, the amount of the refrigerant going into each outdoor unit is decided by comparing the degree of superheat of the current outdoor unit and the average degree of superheat (system); the amount of the refrigerant going into each outdoor unit is adjusted from the overall aspect of the system so that the compressor can be enabled to be within an excellent running range, and therefore, the problems caused by overhigh or insufficient superheat of the compressor can be avoided and the reliability of the multi-split air-conditioner during operation is improved.

Description

technical field [0001] The invention relates to refrigeration technology, in particular to a method for controlling refrigerants in parallel and multi-connected units. Background technique [0002] In a multi-connected system with multiple outdoor units connected in parallel, since the size of the heat exchanger and the suction capacity of the compressors of each outdoor unit may be different, the operating environment and system load will also change over time. Various differences will lead to uneven distribution of the refrigerant returned from the indoor units among the outdoor units when the parallel outdoor units are in heating operation. Some outdoor units are allocated less refrigerant, which is easier to evaporate in the heat exchanger of the outdoor unit and cause overheating; some outdoor units are allocated more refrigerant, and the heat exchanger of the outdoor unit has limited heat exchange capacity and cannot evaporate completely. As a result, the superheat o...

AI Technical Summary

Problems solved by technology

[0002] In a multi-connected system with multiple outdoor units connected in parallel, since the size of the heat exchanger and the suction capacity of the compressors of each outdoor unit may be different, the operating environment and system load will also change over time. Various differences will lead to uneven distribution of the refrigerant returned from the indoor units among the outdoor units when the parallel outdoor units are in heating operation.

Some outdoor units are allocated less refrigerant, which is easier to evaporate in the heat exchanger of the outdoor unit and cause overheating; some outdoor units are allocated more refrigerant, and the heat exchanger of the outdoor unit has limited heat exchange capacity and cannot completely evaporated

As a result, the superheat of some compressors is too high, and the superheat of some compressors is too low

Excessively high superheat of the compressor will cause poor heat dissipation of the compressor motor. Excessively high temperature will also cause the refrigerated oil in the compressor to deteriorate easily and cause poor lubrication, which will affect the life of the compressor; The refrigerant at the suction port may exist in the form of liquid. Too much refrigerant that has not evaporated completely has poor compressibility, which will increase the current power of the compressor. At the same time, the liquid refrigerant will dilute the refrigeration oil, making it difficult to Refrigerant oil in the compression chamber of the machine is reduced, and the wear of the compression chamber is aggravated

The existing adjustment methods generally target the compressor of a single outdoor unit. However, the adjustment of each outdoor unit in the multi-connected system will affect each other, and the multi-connected system cannot be controlled as a whole.

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