Freezer and air conditioner

Abstract

A freezer and an air conditioner that have a refrigerant circuit with an evaporator constructed such that a refrigerant enters from the lower side and exits from the upper side, in which the width of control when evaporation ability of the evaporator is controlled by an expansion valve is increased. An air conditioner (1) has a refrigerant circuit (12) and a first oil return circuit (101). The refrigerant circuit (12) is constructed by connecting utilization side refrigerant circuits (12a, 12b, 12c) to a heat source side refrigerant circuit (12d). The heat source side refrigerant circuit (12d) is constructed by connecting a compression mechanism (21), a heat source side heat exchanger (23) formed such that, when it functions as an evaporator, the refrigerant enters from the lower side and exits from the upper side, and a heat source side expansion valve (24). A freezing machine oil and refrigerant combined so as not to separate into two layers in temperatures of 30 DEG C or below are used. The first oil return circuit (101) is connected to the lower section of the heat source side heat exchanger (23) and returns a freezing machine oil received in the heat exchanger (23) to the compression mechanism (21) together with the refrigerant.

Description

technical field [0001] The present invention relates to a refrigeration device and an air conditioner, and more particularly to a refrigeration device and an air conditioner having a refrigerant circuit including an evaporator for allowing refrigerant to flow in from the lower side and outflow from the upper side. Background technique [0002] Conventionally, there is a refrigeration system having a vapor compression refrigerant circuit including a heat exchanger serving as an evaporator of the refrigerant and allowing the refrigerant to flow in from the lower side and out from the upper side (for example, refer to Patent Document 1). In this refrigerating device, in order to prevent the refrigerating machine oil from stagnating in the evaporator, the refrigerating machine oil that has accumulated is discharged from the vicinity of the liquid surface of the refrigerant in a state where the specific gravity is lower than that of the refrigerant and separated into two layers fl...

AI Technical Summary

Problems solved by technology

However, once the control of reducing the opening degree of the heat source side expansion valve is performed, there is a problem that the refrigerant pressure on the downstream side of the heat source side expansion valve (specifically, between the heat source side expansion valve and the utilization side refrigerant circuit) There is a tendency to decrease and cannot be stabilized, and the control to reduce the condensing capacity of the heat source side refrigerant circuit cannot be performed stably

However, when the heat source side heat exchanger is made to function as an evaporator with a small evaporation capacity, such as when the air conditioning load in the plurality of use side refrigerant circuits becomes very small, even if the heat source side expansion valve The amount of refrigerant flowing through the heat source side heat exchanger is reduced due to the opening degree, and the opening of the heat source side expansion valve cannot be too small due to the restriction of the refrigerant liquid level in the heat source side heat exchanger. Therefore, only adjusting The opening degree of the heat source side expansion valve cannot sufficiently control the evaporating capacity. As a result, control must be performed by closing some of the plurality of heat source side expansion valves and reducing the number of heat source side heat exchangers functioning as evaporators. Evaporation capacity, or reduction of evaporative capacity by making some of the plurality of heat source side heat exchangers function as condensers, thereby offsetting the evaporative capacity of the heat source side heat exchangers functioning as evaporators

[0009] Therefore, there is a problem that if a plurality of heat source side heat exchangers are installed, the number of parts and the cost will increase accordingly. In addition, when a part of the plurality of heat source side heat exchangers functions as a condenser to reduce the evaporation capacity, The amount of refrigerant compressed in the compressor will correspondingly increase the amount of refrigerant condensed in the heat exchanger on the heat source side, and the COP of the overall air-conditioning load of multiple refrigerant circuits on the utilization side will become worse under smaller operating conditions

[0011] Therefore, there is a problem that if a plurality of heat source side heat exchangers are installed, the number of parts and the cost will increase accordingly. In addition, when a part of the plurality of heat source side heat exchangers functions as an evaporator to reduce the condensation capacity, The amount of refrigerant compressed in the compressor will correspondingly increase the amount of refrigerant evaporated in the heat exchanger on the heat source side, and the COP of the overall air-conditioning load of multiple refrigerant circuits on the utilization side will become worse under smaller operating conditions

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