Refrigeration system

Abstract

In a refrigerant circuit (20), an air conditioning unit (12), a cold-storage showcase (13), and a freeze-storage showcase (14) are connected in parallel to an outdoor unit (11). When placing an indoor heat exchanger (71) of the air conditioning unit (12) in the thermo-off state, a degree-of-opening control means (101) provides control so that an indoor expansion valve (72) is placed in the fully closed state. Thereafter, the degree-of-opening control means (101) detects the accumulated amount of refrigerant within the indoor heat exchanger (71) and then adjusts the degree of opening of the indoor expansion valve (72) depending on the refrigerant amount detected.

Description

TECHNICAL FIELD[0001]This invention generally relates to a refrigeration system having a plurality of utilization side units and more particularly to the prevention of the accumulation of refrigerant (“refrigerant's falling-asleep” in the industry jargon) in a heating heat exchanger placed out of operation.BACKGROUND ART[0002]In the past, various refrigeration systems that perform a refrigeration cycle by the circulation of refrigerant have widely been applied to air conditioning systems and other like systems. There is known, as such a type of refrigeration system, a so-called multi-type refrigeration system in which a plurality of utilization side units are connected in parallel to a heat source side unit.[0003]For example, JP-A-1996-159590 (hereinafter referred to as the patent document) shows a refrigeration system which includes a single heat source side unit having a compressor and a heat source side heat exchanger, and two utilization side units each having a utilization side...

AI Technical Summary

Benefits of technology

[0024]in the first aspect of the present invention, when carrying out an operation to stop the heating heat exchanger (71), the degree of opening of the expansion valve (72) is reduced by a first control operation, which is followed by the execution of a second control operation to adjust the degree of opening of the expansion valve (72) based on the index indicative of the accumulated amount of refrigerant within the heating heat exchanger (71). Therefore, in accordance with the present invention, it becomes possible that, upon the detection of the occurrence of “refrigerant's falling-asleep” within the heating heat exchanger (71), the degree of opening of the expansion valve (72) is increased, whereby the refrigerant accumulated within the heating heat exchanger (71) can be fed to the other utilization side units (13, 14). That is, in accordance with the present invention, it is ensured that the elimination of “refrigerant's falling-asleep” within the heating heat exchanger (71) in the out-of-operation state is accomplished without fail, thereby making it possible to prevent the other utilization side units (13, 14) from capacity degradation.

[0025]In addition, in accordance with the present invention, the degree of opening of the expansion valve (72) can be made small if the accumulated amount of refrigerant within the heating heat exchanger (71) is small. Therefore, it is avoided that an excess supply of refrigerant is provided to the heating heat exchanger (71) despite the fact that the elimination of “refrigerant's falling-asleep” within the heating heat exchanger (71) has already been accomplished. This makes it possible to satisfactorily ensure the supply of refrigerant to the other utilization side units (13, 14). Accordingly, it becomes possible to still further effectively prevent the other utilization side units (13, 14) from capacity degradation.

[0026]In addition, in the second aspect of the present invention, the first control operation is carried out to place the expansion valve (72) in the fully closed state, when stopping the heating heat exchanger (71). Therefore, in accordance with the present invention, it is possible to further increase the supply of refrigeration to the other utilization side units (13, 14), thereby enhancing their capacity.

[0027]In addition, in the third aspect of the present invention, it is arranged such that, in the second control operation, the accumulated amount of refrigerant within the hea

Problems solved by technology

This gives rise to the problem that the other utilization sid

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