WO2019189748A1

WO2019189748A1 - Refrigeration device

Info

Publication number: WO2019189748A1
Application number: PCT/JP2019/013970
Authority: WO
Inventors: 竹上　雅章; 明敏上野; 堀田　卓也
Original assignee: ダイキン工業株式会社
Priority date: 2018-03-30
Filing date: 2019-03-29
Publication date: 2019-10-03
Also published as: JP6593483B2; JP2019178821A

Abstract

A refrigeration device (10), having a refrigerant circuit (11) in which a cooling device heat exchanger (83) and an indoor heat exchanger (93) are connected to a common-use outdoor heat exchanger (22), is provided with a first auxiliary heat exchanger (110) having a first high-pressure flow channel (111) and a first low-pressure flow channel (112), wherein the first high-pressure flow channel (111) is connected to the cooling device heat exchanger (83) which has a lower evaporation temperature, while a refrigerant outflow side of the first low-pressure flow channel (112) and a refrigerant intake part of a second compressor (41) are connected to each other via a first auxiliary intake pipe (118).

Description

Refrigeration equipment

This disclosure relates to a refrigeration apparatus.

Conventionally, there is a refrigeration apparatus that is provided with a heat source heat exchanger that is shared with a plurality of heat exchangers and that operates at different evaporation temperatures in each heat exchanger (see Patent Document 1). This refrigeration apparatus includes a first use heat exchanger for refrigeration (refrigeration equipment) having a low evaporation temperature, and a second use heat exchanger for air conditioning whose evaporation temperature is higher than that of the first use heat exchanger. Yes. Respective compressors (first compressor and second compressor) are connected to the respective heat exchangers, and the refrigerant evaporated in the first heat exchanger is sucked into the first compressor and second heat used. The refrigerant evaporated in the exchanger is sucked into the second compressor whose suction pressure is lower than that of the first compressor.

JP 2014-070829 A

In this type of refrigeration system, the suction pipe of the first compressor and the suction pipe of the second compressor may be connected by a suction communication pipe, and a pressure control valve may be provided in the suction communication pipe. The refrigeration apparatus of Patent Document 1 is also configured as such.

If comprised in this way, by adjusting a pressure control valve, decompressing a part of refrigerant | coolant suck | inhaled from a 2nd utilization heat exchanger to a 2nd compressor, and performing the operation | movement suck | inhaled with a 1st compressor Can do. Therefore, when the cooling capacity of the first usage heat exchanger having a low evaporation temperature is insufficient with respect to the cooling load, a part of the refrigerant of the second usage heat exchanger is sucked into the first usage heat exchanger. Therefore, the lack of cooling capacity is compensated.

However, since the second compressor has a higher suction pressure than the first compressor, when the cooling capacity of the second heat exchanger is insufficient, the shortage of the capacity is regarded as one of the refrigerant of the first heat exchanger. It was not possible to make up with the part.

An object of the present disclosure is to provide a refrigeration apparatus having a refrigerant circuit in which a plurality of heat exchangers having different evaporation temperatures are connected to a common heat source heat exchanger, and the cooling capacity of the heat exchanger having a high evaporation temperature is insufficient. In addition, it is to make up for the lack of ability.

The first aspect of the present disclosure is:
A compression section (30), a heat source heat exchanger (22), and a plurality of utilization heat exchangers (83, 93) are provided, and the plurality of utilization heat exchangers (83, 93) are shared heat source heat exchangers (22 ) And a control unit (100) for controlling the operation of the refrigerant circuit (11).

And this refrigeration equipment
The plurality of utilization heat exchangers (83, 93) includes a first utilization heat exchanger (83) and a second utilization heat exchanger (93),
The compressor (30) is connected to the first compressor (31) having a suction part connected to the first heat exchanger (83) and to the second heat exchanger (93). A second compressor (41),
The refrigerant circuit (11) includes a first auxiliary heat exchanger (110) having a first high-pressure channel (111) and a first low-pressure channel (112), and a refrigerant in the first low-pressure channel (112). A first auxiliary suction channel (118) communicating with the outflow side and the refrigerant suction part of the second compressor (41);
The first auxiliary heat exchanger (110) has the first high-pressure channel (111) connected to a first liquid channel (63) communicating with the first utilization heat exchanger (83), The first low-pressure channel (112) is connected to a first branch channel (115) branched from the first liquid channel (63) and provided with a first pressure reducing mechanism (116). The refrigerant flowing through the high-pressure channel (111) and the refrigerant flowing through the first low-pressure channel (112) are configured to exchange heat,
The evaporating temperature of the refrigerant in the first use heat exchanger (83) is lower than the evaporating temperature of the refrigerant in the second use heat exchanger (93).

In the first aspect, if the cooling capacity of the second utilization heat exchanger (93) is insufficient, the first utilization heat exchanger (83) flows if the first auxiliary heat exchanger (110) is not provided. A part of the refrigerant evaporates in the first low-pressure channel (112), and is sucked into the second compressor (41) through the first auxiliary suction channel (118). As a result, the amount of refrigerant sucked into the second compressor (41) can be increased to increase the amount of refrigerant circulating in the second heat exchanger (93) having a high evaporation temperature, so that the second heat exchanger (93) can be cooled. Increases ability.

According to a second aspect of the present disclosure, in the first aspect,
In claim 1,
A suction communication channel (50) connected to the first suction channel (32) of the first compressor (31) and the second suction channel (42) of the second compressor (41);
A pressure control valve (V5) connected to the suction communication channel (50) and adjustable in opening;
A refrigeration apparatus comprising:

In the second aspect, when the cooling capacity of the first usage heat exchanger (83) is insufficient, a part of the refrigerant sucked from the second usage heat exchanger (93) to the second compressor (41) is removed. The first compressor (31) can perform the operation of reducing the pressure by the pressure control valve (V5) of the suction communication channel (50). As a result, the amount of refrigerant circulating in the first heat exchanger (83) can be increased, and according to the second aspect, the cooling capacity of the first heat exchanger (83) having a low evaporation temperature can be increased. become.

According to a third aspect of the present disclosure, in the first or second aspect,
The controller (100) includes a first refrigeration cycle for sucking the refrigerant evaporated in the first use heat exchanger (83) through the first compressor (31), and the second use heat exchanger (93). When the cooling capacity of the first use heat exchanger (83) is below the cooling load in the operation state in which the second refrigeration cycle for sucking the refrigerant evaporated in the second compressor (41) is performed, the first The opening of the first pressure reducing mechanism (116) is adjusted so that the refrigerant pressure in the one low-pressure channel (112) becomes the suction pressure or intermediate pressure of the second compressor (41), and the first liquid channel A part of the refrigerant flowing through (63) is supplied from the first branch flow path (115) to the second compressor (41) to assist the cooling capacity of the second utilization heat exchanger (93). It is configured to perform auxiliary operation.

In the third aspect, when the cooling capacity of the second heat exchanger (93) falls below the cooling load, the first auxiliary operation is performed to increase the intake refrigerant amount of the second compressor (41) and evaporate. Since the refrigerant circulation amount of the second use heat exchanger (93) having a high temperature can be increased, the cooling capacity of the second use heat exchanger (93) can be increased.

According to a fourth aspect of the present disclosure, in any one of the first to third aspects,
The refrigerant circuit (11) includes a second auxiliary heat exchanger (120) having a second high-pressure channel (121) and a second low-pressure channel (122), and a refrigerant in the second low-pressure channel (122). A second auxiliary suction channel (128) communicating with the outflow side and the refrigerant suction part of the first compressor (31),
The first auxiliary heat exchanger (110) has the second high-pressure channel (121) connected to a second liquid channel (65) communicating with the second utilization heat exchanger (93), The second low-pressure channel (122) branches from the second liquid channel (65) and is connected to a second branch channel (125) provided with a second pressure reducing mechanism (126). The refrigerant flowing through the high-pressure channel (121) and the refrigerant flowing through the second low-pressure channel (122) are configured to exchange heat.

In the 4th mode, if the cooling capacity of the 1st utilization heat exchanger (83) is insufficient, if the 2nd auxiliary heat exchanger (120) is not provided, it will flow to the 2nd utilization heat exchanger (93). A part of the refrigerant evaporates in the second low pressure channel (122), and is sucked into the first compressor (31) through the second auxiliary suction channel (128). As a result, the amount of refrigerant sucked into the first compressor (31) can be increased to increase the refrigerant flow rate of the first use heat exchanger (83) having a low evaporation temperature, so that the cooling capacity of the first use heat exchanger (83) Can be enhanced.

According to a fifth aspect of the present disclosure, in the fourth aspect,
The controller (100) includes a first refrigeration cycle for sucking the refrigerant evaporated in the first use heat exchanger (83) through the first compressor (31), and the second use heat exchanger (93). When the cooling capacity of the second heat exchanger (93) is below the cooling load in the operation state in which the second refrigeration cycle for sucking the refrigerant evaporated in the second compressor (41) is performed, 2 The opening of the second pressure reducing mechanism (126) is adjusted so that the refrigerant pressure in the low-pressure channel (122) becomes the suction pressure or intermediate pressure of the first compressor (31), and the second liquid channel (2) supplying a part of the refrigerant flowing through (65) to the first compressor (31) from the second branch flow path (125) to assist the cooling capacity of the first heat exchanger (83). It is configured to perform auxiliary operation.

In the fifth aspect, when the cooling capacity of the first heat exchanger (83) falls below the cooling load, the second auxiliary operation is performed to increase the intake refrigerant amount of the first compressor (31) and evaporate. Since the refrigerant circulation amount of the first use heat exchanger (83) having a low temperature can be increased, the cooling capacity of the first use heat exchanger (83) can be increased.

FIG. 1 is a piping system diagram of the refrigeration apparatus according to the first embodiment. FIG. 2 is a table comparing operation modes. FIG. 3 is a view corresponding to FIG. 1 showing the flow of the refrigerant in the cooling operation. FIG. 4 is a view corresponding to FIG. 1 and showing the flow of the refrigerant in the cooling operation. FIG. 5 is a view corresponding to FIG. 1 showing the flow of the refrigerant in the cooling / cooling operation. FIG. 6 is a view corresponding to FIG. 1 illustrating the flow of the refrigerant in the heating operation. FIG. 7 is a view corresponding to FIG. 1 showing the flow of the refrigerant in the heating / cooling operation. FIG. 8 is a diagram corresponding to FIG. 1 and showing the flow of the refrigerant in the heating / cooling heat recovery operation. FIG. 9 is a view corresponding to FIG. 1 and showing the flow of the refrigerant in the heating / cooling residual heat operation. FIG. 10 is a flowchart showing the operation of the air conditioning capability assist operation. FIG. 11 is a piping system diagram of the refrigeration apparatus according to the second embodiment. FIG. 12 is a flowchart showing the operation of the cooling capacity assist operation. FIG. 13 is a piping system diagram of the refrigeration apparatus according to the third embodiment.

Embodiment 1
The first embodiment will be described.

<overall structure>
The refrigeration apparatus (10) according to the embodiment is a refrigerator, freezer, showcase and other refrigeration equipment and refrigeration equipment (hereinafter collectively referred to as refrigeration) mainly used for business, Perform indoor air conditioning at the same time. As shown in FIG. 1, the refrigeration apparatus (10) includes an outdoor unit (20) installed outdoors, a cooling unit (80) for cooling the air in the cabinet, and an indoor unit (90 for performing indoor air conditioning) ) And a controller (100). The number of refrigeration units (80) and indoor units (90) is not limited to one, and may be two or more. These units (20, 80, 90) are connected to each other by four connecting pipes (12, 13, 14, 15) to constitute the refrigerant circuit (11). In the refrigerant circuit (11), a refrigeration cycle is performed by circulating the refrigerant. The refrigerant in the refrigerant circuit (11) of the present embodiment is carbon dioxide.

In this refrigerant circuit (11), a cooling heat exchanger (first utilization heat exchanger) (83) and an indoor heat exchanger (second utilization heat exchanger) (a plurality of utilization heat exchangers having different evaporation temperatures) ( 93) is connected in parallel to the outdoor heat exchanger (22), which is a common heat source heat exchanger. The evaporating temperature of the refrigerant in the refrigeration cycle in the refrigerated heat exchanger (83) is lower than the evaporating temperature of the refrigerant in the indoor heat exchanger (93).

<Outdoor unit>
The outdoor unit (20) is installed outdoors. The outdoor unit (20) is provided with an outdoor circuit (21). The outdoor circuit (21) includes a first compressor (31), a second compressor (41), an outdoor heat exchanger (22), an outdoor expansion valve (23), a receiver (24), A cooling heat exchanger (25) is connected.

The first compressor (31) and the second compressor (41) constitute a compression unit (30) that compresses the refrigerant. The first compressor (31) and the second compressor (41) are each configured in a two-stage compression type. A 1st compressor (31) and a 2nd compressor (41) are comprised by the variable capacity type | mold by which rotation speed is variable by adjusting an operating frequency by inverter control.

The first compressor (31) has a first low-stage compression mechanism (31a) and a first high-stage compression mechanism (31b). In the first compressor (31), the refrigerant compressed by the first low stage compression mechanism (31a) is further compressed by the first high stage compression mechanism (31b). The first compressor (31) includes a first suction pipe (first suction flow path) (32), a first relay pipe (33), a first discharge pipe (34), and a first oil return pipe (35). Is connected. The first suction pipe (32) communicates with the suction port of the first low-stage compression mechanism (31a). The inflow end of the first relay pipe (33) communicates with the discharge port of the first low-stage compression mechanism (31a). The outflow end of the first relay pipe (33) communicates with the suction port of the first high-stage compression mechanism (31b). The first discharge pipe (34) communicates with the discharge port of the first high-stage compression mechanism (31b). A first intercooler (36) is connected to the first relay pipe (33). Connected to the first oil return pipe (35) is a first flow rate control valve (37) having a variable opening.

The second compressor (41) has a second low-stage compression mechanism (41a) and a second high-stage compression mechanism (41b). In the second compressor (41), the refrigerant compressed by the second low stage compression mechanism (41a) is further compressed by the second high stage compression mechanism (41b). The second compressor (41) includes a second suction pipe (second suction flow path) (42), a second relay pipe (43), a second discharge pipe (44), and a second oil return pipe (45). Is connected. The second suction pipe (42) communicates with the suction port of the second low-stage compression mechanism (41a). The inflow end of the second relay pipe (43) communicates with the discharge port of the second low-stage compression mechanism (41a). The outflow end of the second relay pipe (43) communicates with the suction port of the second high-stage compression mechanism (41b). The second discharge pipe (44) communicates with the discharge port of the second high-stage compression mechanism (41b). A second intercooler (46) is connected to the second relay pipe (43). A second flow rate control valve (47) having a variable opening is connected to the second oil return pipe (45).

The first oil separator (38) is connected to the first discharge pipe (34). A second oil separator (48) is connected to the second discharge pipe (44). The oil separated by the first oil separator (38) and the oil separated by the second oil separator (48) are cooled by the oil cooler (39). The oil cooled by the oil cooler (39) is returned to the first compressor (31) via the first oil return pipe (35). The oil cooled by the oil cooler (39) is returned to the second compressor (41) via the second oil return pipe (45).

The suction communication pipe (suction communication flow path) (50) is connected to the first suction pipe (32) and the second suction pipe (42). The suction communication pipe (50) is provided with a pressure control valve (V5) having a variable opening. The outflow end of the first discharge pipe (34) and the outflow end of the second discharge pipe (44) are connected to the merged discharge pipe (52).

The bridge circuit (70) constitutes a flow path switching mechanism. The bridge circuit (70) can open and close the first to fourth flow paths (71, 72, 73, 74) connected in a bridge shape and the respective flow paths (71, 72, 73, 74). With two valves (V1, V2, V3, V4). The first flow path (71) has a first valve (V1), the second flow path (72) has a second valve (V2), and the third flow path (73) has a third valve (V3). The fourth valve (V4) is connected to the fourth flow path (74). In the present embodiment, all of the four valves (V1, V2, V3, V4) are constituted by flow rate control valves whose opening degrees are variable. The four valves (V1, V2, V3, V4) have a backflow prevention mechanism. Specifically, the valves (V1, V2, V3, V4) allow the refrigerant to flow in the directions indicated by the arrows in FIG. 1, and prohibit the refrigerant in the opposite direction.

The bridge circuit (70) has four connection points (C1, C2, C3, C4) from the first to the fourth. The first connection point (C1) connects the inflow portion of the first flow path (71) and the inflow portion of the second flow path (72). The second connection point (C2) connects the outflow portion of the first flow path (71) and the inflow portion of the third flow path (73). The third connection point (C3) connects the outflow portion of the second flow path (72) and the inflow portion of the fourth flow path (74). The fourth connection point (C4) connects the outflow portion of the third flow path (73) and the outflow portion of the fourth flow path (74).

The first connection point (C1) is connected to the first discharge pipe (34) and the second discharge pipe (44) (the discharge section of the compression section (30)) via the merging discharge pipe (52). The second connection point (C2) is connected to the gas side end of the outdoor heat exchanger (22) (heat source heat exchanger). A 3rd connection point (C3) is connected with the gas side edge part of an indoor heat exchanger (93) (2nd utilization heat exchanger). The fourth connection point (C4) is connected to the second suction pipe (42) (the suction part of the compression part (30)) via the suction relay pipe (58).

The outdoor heat exchanger (22) constitutes a heat source heat exchanger. The outdoor heat exchanger (22) is a fin-and-tube heat exchanger. An outdoor fan (22a) is provided in the vicinity of the outdoor heat exchanger (22). The refrigerant flowing through the outdoor heat exchanger (22) and the air blown by the outdoor fan (22a) exchange heat. The first intercooler (36), the second intercooler (46), the oil cooler (39), and the outdoor heat exchanger (22) are adjacent to each other so as to share an outdoor fan (22a) and fins (not shown). Arranged.

The first pipe (61) is connected between the outdoor heat exchanger (22) and the receiver (24). An outdoor expansion valve (23) is connected to the first pipe (61). The outdoor expansion valve (23) is an electronic expansion valve having a variable opening.

The receiver (24) constitutes a container for storing the refrigerant. The supercooling heat exchanger (25) has a high pressure side channel (25a) and a low pressure side channel (25b). In the supercooling heat exchanger (25), the refrigerant flowing through the high-pressure channel (25a) and the refrigerant flowing through the low-pressure channel (25b) exchange heat.

The second pipe (62) is connected between the receiver (24) and the high pressure side flow path (25a) of the supercooling heat exchanger (25). The outflow part of the high-pressure side flow path (25a) of the supercooling heat exchanger (25) is a liquid pipe (first liquid pipe (first liquid flow path)) on the cold heat exchanger (83) side. One end of the three pipes (63) is connected. The first liquid branch pipe (63a) and the second liquid branch pipe (63b) are connected to the other end of the third pipe (63). The first liquid branch pipe (63a) is connected to the liquid side end of the chilled heat exchanger (83) via the first liquid communication pipe (12). The second liquid branch pipe (63b) is connected to the liquid side end of the indoor heat exchanger (93) via the second liquid communication pipe (14).

一端 One end of the introduction pipe (53) is connected to the third pipe (63). In the middle of the introduction pipe (53), the pressure reducing valve (54) and the high-pressure side flow path (25a) are connected. The pressure reducing valve (54) has a backflow prevention mechanism. The pressure reducing valve (54) allows the refrigerant to flow in the direction indicated by the arrow in FIG. 1 and prohibits the refrigerant from flowing in the opposite direction.

The other end of the introduction pipe (53) is connected to the inflow end of the first introduction branch pipe (53a) and the inflow end of the second introduction branch pipe (53b). The outflow end of the first introduction branch pipe (53a) is connected to the first relay pipe (33). The outflow end of the second introduction branch pipe (53b) is connected to the second relay pipe (43). A third flow rate control valve (55) having a variable opening is connected to the first introduction branch pipe (53a). A fourth flow rate control valve (56) having a variable opening is connected to the second introduction branch pipe (53b).

The fourth pipe (64) is connected between the first pipe (61) and the third pipe (63). A fifth pipe (65) which is a liquid pipe (second liquid pipe) on the indoor heat exchanger (93) side is connected between the first pipe (61) and the second liquid communication pipe (14). . A second liquid branch pipe (63b) is connected to the fifth pipe (65). One end of a gas vent pipe (67) is connected to the top of the receiver (24). The other end of the gas vent pipe (67) is connected to the introduction pipe (53) downstream of the pressure reducing valve (54). A gas vent valve (68) is connected to the gas vent pipe (67). The gas vent valve (68) is an expansion valve having a variable opening.

In the first discharge pipe (34), the second discharge pipe (44), the first pipe (61), the fourth pipe (64), the fifth pipe (65), and the second liquid branch pipe (63b) described above, A check valve (CV) is provided for each. Each check valve (CV) allows the refrigerant to flow in the direction indicated by each arrow in FIG. 1 and prohibits the refrigerant from flowing in the opposite direction.

<Cooling unit>
The refrigeration unit (80) is installed in, for example, a refrigerated warehouse. The refrigeration unit (80) is provided with a refrigeration circuit (81). A first liquid communication pipe (12) is connected to the liquid side end of the refrigeration circuit (81). A first gas communication pipe (13) is connected to the gas side end of the refrigeration circuit (81). The chilling circuit (81) is provided with a chilling expansion valve (82) and a chilling heat exchanger (83) in order from the liquid side end. The cold expansion valve (82) is an electronic expansion valve having a variable opening.

The chilled heat exchanger (83) constitutes a first use heat exchanger. The refrigerated heat exchanger (83) is a fin-and-tube heat exchanger. An internal fan (83a) is provided in the vicinity of the refrigerated heat exchanger (83). The refrigerant flowing through the chilled heat exchanger (83) exchanges heat with the air blown by the internal fan (83a). The gas side end of the chilled heat exchanger (83) is connected to the first suction pipe (32) of the first compressor (31) via the first gas communication pipe (13).

<Indoor unit>
The indoor unit (90) is installed indoors. The indoor unit (90) is provided with an indoor circuit (91). A second gas communication pipe (15) is connected to the gas side end of the indoor circuit (91). A second liquid communication pipe (14) is connected to the liquid side end of the indoor circuit (91). The indoor circuit (91) is provided with an indoor expansion valve (92) and an indoor heat exchanger (93) in order from the liquid side end. The indoor expansion valve (92) is an electronic expansion valve having a variable opening.

The indoor heat exchanger (93) constitutes a second utilization heat exchanger. The indoor heat exchanger (93) is a fin-and-tube heat exchanger. An indoor fan (93a) is provided in the vicinity of the indoor heat exchanger (93). The refrigerant flowing through the indoor heat exchanger (93) and the air blown by the indoor fan (93a) exchange heat. The gas side end of the indoor heat exchanger (93) is connected to the second gas communication pipe (15), the fourth flow path (74) of the bridge circuit (70), and the suction relay pipe (58) via the second gas communication pipe (15). It connects with the 2nd suction pipe (42) of a compressor (41).

<First auxiliary heat exchanger>
As described above, the compression unit (30) of the outdoor unit (20) is sucked into the chilled heat exchanger (83) having a low evaporation temperature of the refrigeration cycle among the plurality of heat exchangers (83, 93). The suction part (suction port) was connected to the first compressor (31) to which the part (suction port) was connected and the indoor heat exchanger (93) having a higher evaporation temperature than the cold heat exchanger (83) A second compressor (41). In this embodiment, in order to compensate for the shortage of the capacity of the second compressor (41) that sucks and compresses the refrigerant flowing through the indoor heat exchanger (93), the outdoor unit (20) is provided with the first auxiliary heat exchanger ( 110). That is, the first auxiliary heat exchanger (110) is a heat exchanger for assisting the capabilities of the second compressor (41) and the indoor heat exchanger (93).

The first auxiliary heat exchanger (110) has a first high-pressure channel (111) and a first low-pressure channel (112). The first high-pressure channel (111) is connected to the third pipe (first liquid pipe) (63). In the first low-pressure channel (112), the refrigerant inflow end is connected to the first branch pipe (first branch channel) (115) branched from the third pipe (first liquid pipe) (63). The first branch pipe (115) is provided with a first expansion valve as a first pressure reducing valve (first pressure reducing mechanism) (116). In the first auxiliary heat exchanger (110), the refrigerant flowing through the first high-pressure channel (111) and the refrigerant flowing through the first low-pressure channel (112) exchange heat.

A first auxiliary suction pipe (first auxiliary suction flow path) (118) is connected to the refrigerant outflow end of the first low pressure flow path (112). The first auxiliary suction pipe (118) is connected to the suction port of the second low-stage compression mechanism (41a), which is the suction part of the second compressor (41), via a suction relay pipe (58). The first auxiliary suction pipe (118) may be connected to the suction port of the second high-stage compression mechanism (41b).

<Sensor>
Various sensors are provided in the refrigeration apparatus (10). Examples of indices detected by these sensors include the temperature / pressure of the high-pressure refrigerant in the refrigerant circuit (11), the temperature / pressure of the low-pressure refrigerant, the temperature / pressure of the intermediate-pressure refrigerant, and the temperature of the refrigerant in the outdoor heat exchanger (22). , The temperature of the refrigerant in the cold heat exchanger (83), the temperature of the refrigerant in the indoor heat exchanger (93), the degree of suction superheat of each compressor (31, 41), the discharge superheat of each compressor (31, 41) Temperature, outdoor air temperature, internal air temperature, and indoor air temperature.

In FIG. 1, among these sensors, an outside air temperature sensor (94), a first refrigerant temperature sensor (95), a second refrigerant temperature sensor (96), and an inside air temperature sensor (97), which will be described in detail later, are shown. Show.

<controller>
The controller (100) that is a control unit includes a microcomputer mounted on a control board and a memory device (specifically, a semiconductor memory) that stores software for operating the microcomputer. The controller (100) controls each device of the refrigeration apparatus (1) based on the operation command and the detection signal of the sensor. The operation of the refrigeration apparatus (1) is switched by the control of each device by the controller (100). The controller (100) also controls the air conditioning capability auxiliary operation when the air conditioning capability is insufficient.

-Driving operation-
The operation of the refrigeration apparatus (1) will be described in detail. As shown in FIG. 2, the operation of the refrigeration system includes a cooling operation, a cooling operation, a cooling / cooling operation, a heating operation, a heating / cooling operation, a heating / cooling heat recovery operation, a heating / cooling residual heat operation, And defrost operation.

In the cooling operation, the cooling unit (80) is operated and the indoor unit (90) is stopped. In the cooling operation, the cooling unit (80) stops and the indoor unit (90) performs cooling. In the cooling / cooling operation, the cooling unit (80) is operated, and the indoor unit (90) performs cooling. In the heating operation, the cooling unit (80) stops and the indoor unit (90) performs heating. In any of the heating / cooling operation, the heating / cooling heat recovery operation, and the heating / cooling residual heat operation, the cooling unit (80) is operated, and the indoor unit (90) performs heating. In the defrost operation, the cooling unit (80) is operated, and an operation of melting frost on the surface of the outdoor heat exchanger (22) is performed.

The heating / cooling operation is executed under the condition that the required heating capacity of the indoor unit (90) is relatively large, and the insufficient amount of heat is taken in from the outside. The heating / cooling residual heat operation is executed under the condition that the required heating capacity of the indoor unit (90) is relatively small, and an excessive amount of heat is released to the outside. Heating / cooling heat recovery operation is performed under the condition that the required heating capacity of the indoor unit (90) is between heating / cooling operation and heating / cooling residual heat operation (conditions where cooling and heating are balanced). Executed.

As shown in FIG. 2, in each operation, one or both of the first compressor (31) and the second compressor (41) are operated. When operating only the first compressor (31), the pressure control valve (V5) is closed. When only the second compressor (41) is operated, the pressure control valve (V5) is opened. When the first compressor (31) and the second compressor (41) are operated, the pressure control valve (V5) is opened except for the cooling / cooling operation and the heating / cooling operation. In the following description of each operation, a case where the first compressor (31) and the second compressor (41) are operated is illustrated.

<Cooling operation>
In the cooling operation shown in FIG. 3, the first valve (V1) is opened, and the second valve (V2), the third valve (V3), and the fourth valve (V4) are closed. The outdoor expansion valve (23) is fully opened, the opening degree of the cold expansion valve (82) is adjusted by superheat control, and the indoor expansion valve (92) is fully closed. A refrigeration cycle is performed in which the refrigerant compressed in the compressor (30) radiates heat in the outdoor heat exchanger (22) and evaporates in the cold heat exchanger (83).

Specifically, the refrigerant compressed by the first compressor (31) and the second compressor (41) passes through the first flow path (71) of the bridge circuit (70), and the outdoor heat exchanger (22 ). In the outdoor heat exchanger (22), the heat of the refrigerant is released to the outdoor air. The refrigerant radiated by the outdoor heat exchanger (22) flows through the chilled heat exchanger (83) via the receiver (24) and the high-pressure channel (25a) of the supercooling heat exchanger (25). In the refrigerated heat exchanger (83), the internal air is cooled by the evaporated refrigerant. The refrigerant evaporated in the cold heat exchanger (83) is sucked into the first compressor (31) and the second compressor (41).

In the cooling operation and other operations, the refrigerant cooling operation for cooling the intermediate pressure refrigerant is appropriately performed as follows. At least a part of the refrigerant compressed by the first low-stage compression mechanism (31a) of the first compressor (31) flows through the first intercooler (36) via the first relay pipe (33). In the first intercooler (36), the heat of the refrigerant is released to the outdoor air. The refrigerant cooled by the first intercooler (36) is further compressed by the first higher stage compression mechanism (31b) of the first compressor (31). Similarly, at least a part of the refrigerant compressed by the second low-stage compression mechanism (41a) of the second compressor (41) passes through the second intercooler (46) via the second relay pipe (43). Flowing. In the second intercooler (46), the heat of the refrigerant is released to the outdoor air. The refrigerant cooled by the second intercooler (46) is further compressed by the second higher stage compression mechanism (41b) of the second compressor (41).

In the cooling operation and other operations, an injection operation for introducing the refrigerant that has flowed through the low pressure side flow path (25b) of the supercooling heat exchanger (25) into each compressor (31, 41) is appropriately performed. In each figure, the flow of the refrigerant during the injection operation is not shown. Part of the refrigerant in the second pipe (62) flows into the introduction pipe (53). Further, the gas refrigerant in the receiver (24) flows into the introduction pipe (53) via the gas vent pipe (67). The refrigerant flowing into the introduction pipe (53) is depressurized by the pressure reducing valve (54) and then flows through the low pressure side flow path (25b). In the refrigerated heat exchanger (83), the heat of the refrigerant flowing through the high-pressure channel (25a) is imparted to the refrigerant flowing through the low-pressure channel (25b). The refrigerant that has flowed out of the low-pressure channel (25b) is divided into the first introduction branch pipe (53a) and the second introduction branch pipe (53b). The refrigerant in the first introduction branch pipe (53a) is introduced into the first high-stage compression mechanism (31b) of the first compressor (31) via the first relay pipe (33). The refrigerant in the second introduction branch pipe (53b) is introduced into the second high-stage compression mechanism (41b) of the second compressor (41) via the second relay pipe (43).

<Cooling operation>
In the cooling operation shown in FIG. 4, the first valve (V1) and the fourth valve (V4) are opened, and the second valve (V2) and the third valve (V3) are closed. The outdoor expansion valve (23) is fully opened, the cold expansion valve (82) is fully closed, and the opening degree of the indoor expansion valve (92) is controlled by superheat control. A refrigeration cycle is performed in which the refrigerant compressed in the compressor (30) radiates heat in the outdoor heat exchanger (22) and evaporates in the cold heat exchanger (83).

Specifically, the refrigerant compressed by the first compressor (31) and the second compressor (41) passes through the first flow path (71) of the bridge circuit (70), and the outdoor heat exchanger (22 ). In the outdoor heat exchanger (22), the heat of the refrigerant is released to the outdoor air. The refrigerant radiated by the outdoor heat exchanger (22) flows through the indoor heat exchanger (93) via the receiver (24) and the high-pressure channel (25a) of the supercooling heat exchanger (25). In the indoor heat exchanger (93), the indoor air is cooled by the evaporating refrigerant. The refrigerant evaporated in the indoor heat exchanger (93) passes through the fourth flow path (74) and the suction relay pipe (58) of the bridge circuit (70), and the first compressor (31) and the second compressor ( 41) Inhaled.

<Cooling / cooling operation>
In the cooling / cooling operation shown in FIG. 5, the first valve (V1) and the fourth valve (V4) are opened, and the second valve (V2), the third valve (V3) and the pressure control valve (V5) are opened. Closed. The outdoor expansion valve (23) is fully opened, and the openings of the cold expansion valve (82) and the indoor expansion valve (92) are controlled by superheat control. The refrigerant compressed in the compression unit (30) dissipates heat in the outdoor heat exchanger (22) and evaporates in the cold heat exchanger (83) and the indoor heat exchanger (93).

Specifically, the refrigerant compressed by the first compressor (31) and the second compressor (41) passes through the first flow path (71) of the bridge circuit (70), and the outdoor heat exchanger (22 ). In the outdoor heat exchanger (22), the heat of the refrigerant is released to the outdoor air. The refrigerant dissipated in the outdoor heat exchanger (22) passes through the receiver (24), the high-pressure side flow path (25a) of the supercooling heat exchanger (25), and the cold heat exchanger (83) and the indoor heat exchange. Flows through the vessel (93). In the refrigerated heat exchanger (83), the internal air is cooled by the evaporated refrigerant. The refrigerant evaporated in the cold heat exchanger (83) is sucked into the first compressor (31) through the first gas communication pipe (13). The refrigerant evaporated in the indoor heat exchanger (93) is sucked into the second compressor (41) via the fourth flow path (74) and the suction relay pipe (58) of the bridge circuit (70).

<Heating operation>
In the heating operation shown in FIG. 6, the second valve (V2) and the third valve (V3) are opened, and the first valve (V1) and the fourth valve (V4) are closed. The degree of superheat of the outdoor expansion valve (23) is controlled, the cold expansion valve (82) is fully closed, and the indoor expansion valve (92) is fully open. A refrigeration cycle is performed in which the refrigerant compressed by the compression unit (30) dissipates heat in the indoor heat exchanger (93) and evaporates in the outdoor heat exchanger (22).

Specifically, the refrigerant compressed by the first compressor (31) and the second compressor (41) passes through the second flow path (72) and the second gas connection pipe (15) of the bridge circuit (70). It flows through the indoor heat exchanger (93). In the indoor heat exchanger (93), the indoor air is heated by the radiating refrigerant. The refrigerant radiated by the indoor heat exchanger (93) flows through the outdoor heat exchanger (22) via the receiver (24) and the high-pressure channel (25a) of the supercooling heat exchanger (25). In the outdoor heat exchanger (22), the refrigerant absorbs heat from the room air and evaporates. The refrigerant evaporated in the outdoor heat exchanger (22) passes through the third flow path (73) and the suction relay pipe (58) of the bridge circuit (70), and the first compressor (31) and the second compressor ( 41) Inhaled.

<Heating / Cooling operation>
In the heating / cooling operation shown in FIG. 7, the second valve (V2) and the third valve (V3) are opened, and the first valve (V1), the fourth valve (V4) and the pressure control valve (V5) are opened. Closed. The opening degree of the outdoor expansion valve (23) and the cold expansion valve (82) is superheated, and the indoor expansion valve (92) is fully opened. The refrigerant compressed in the compression unit (30) dissipates heat in the indoor heat exchanger (93) and evaporates in the outdoor heat exchanger (22) and the cold heat exchanger (83).

Specifically, the refrigerant compressed by the first compressor (31) and the second compressor (41) passes through the second flow path (72) and the second gas connection pipe (15) of the bridge circuit (70). It flows through the indoor heat exchanger (93). In the indoor heat exchanger (93), the indoor air is heated by the radiating refrigerant. The refrigerant that dissipated heat in the indoor heat exchanger (93) passes through the receiver (24) and the high-pressure side flow path (25a) of the supercooling heat exchanger (25), and the cold heat exchange is performed in the outdoor heat exchanger (22). Flows through the vessel (83). In the outdoor heat exchanger (22), the refrigerant absorbs heat from the room air and evaporates. The refrigerant evaporated in the outdoor heat exchanger (22) is sucked into the second compressor (41) via the third flow path (73) and the suction relay pipe (58) of the bridge circuit (70). In the refrigerated heat exchanger (83), the internal air is cooled by the evaporated refrigerant. The refrigerant evaporated in the cold heat exchanger (83) is sucked into the first compressor (31) through the first gas communication pipe (13).

<Heating / Cooling heat recovery operation>
In the heating / cooling heat recovery operation shown in FIG. 8, the second valve (V2) is opened, and the first valve (V1) and the fourth valve (V4) are closed. The third valve (V3) is open as a rule. The outdoor expansion valve (23) is fully closed, the degree of opening of the cold expansion valve (82) is superheated, and the indoor expansion valve (92) is fully opened. A refrigeration cycle is performed in which the refrigerant compressed by the compression unit (30) dissipates heat in the indoor heat exchanger (93) and evaporates in the cold heat exchanger (83). At this time, the outdoor heat exchanger (22) is stopped.

Specifically, the refrigerant compressed by the first compressor (31) and the second compressor (41) passes through the second flow path (72) and the second gas connection pipe (15) of the bridge circuit (70). It flows through the indoor heat exchanger (93). In the indoor heat exchanger (93), the indoor air is heated by the radiating refrigerant. The refrigerant radiated by the indoor heat exchanger (93) flows through the chilled heat exchanger (83) via the receiver (24) and the high-pressure channel (25a) of the supercooling heat exchanger (25). In the refrigerated heat exchanger (83), the internal air is cooled by the evaporated refrigerant. The refrigerant evaporated in the cold heat exchanger (83) is sucked into the first compressor (31) and the second compressor (41) via the first gas communication pipe (13).

<Heating / Cooling residual heat operation>
In the heating / cooling residual heat operation shown in FIG. 9, the first valve (V1) and the second valve (V2) are opened, and the third valve (V3) and the fourth valve (V4) are closed. The outdoor expansion valve (23) and the indoor expansion valve (92) are fully opened, and the degree of opening of the cold expansion valve (82) is superheated. The refrigerant compressed in the compression unit (30) dissipates heat in the outdoor heat exchanger (22) and the indoor heat exchanger (93) and evaporates in the cold heat exchanger (83).

Specifically, the refrigerant compressed by the first compressor (31) and the second compressor (41) is divided into the first flow path (71) and the second flow path (72) of the bridge circuit (70). To do. The refrigerant that has flowed out of the first flow path (71) flows through the outdoor heat exchanger (22). In the outdoor heat exchanger (22), the heat of the refrigerant is released to the outdoor air. The refrigerant that has flowed out of the second flow path (72) flows through the indoor heat exchanger (93) via the second gas communication pipe (15). In the indoor heat exchanger (93), the indoor air is heated by the radiating refrigerant. The refrigerant dissipated by the indoor heat exchanger (93) merges with the refrigerant dissipated by the outdoor heat exchanger (22), and passes through the high-pressure channel (25a) of the receiver (24) and supercooling heat exchanger (25). It flows through a chilled heat exchanger (83) via. In the refrigerated heat exchanger (83), the internal air is cooled by the evaporated refrigerant. The refrigerant evaporated in the cold heat exchanger (83) is sucked into the first compressor (31) and the second compressor (41) via the first gas communication pipe (13).

<Defrost operation>
The refrigerant flow in the defrost operation is the same as that in the cooling operation shown in FIG. That is, the refrigerant compressed by the first compressor (31) and the second compressor (41) dissipates heat in the outdoor heat exchanger (22). Thereby, it melts with frost on the surface of the outdoor heat exchanger (22). The refrigerant used for defrosting the outdoor heat exchanger (22) evaporates in the indoor heat exchanger (93), and is then sucked into the first compressor (31) and the second compressor (41).

-Air-conditioning capacity auxiliary operation-
In the present embodiment, the first refrigeration cycle for sucking the refrigerant evaporated in the cold heat exchanger (83) with the first compressor (31), and the refrigerant evaporated in the indoor heat exchanger (93) with the second compressor If the cooling capacity of the indoor heat exchanger (93) is insufficient in the operation state (the state of the cooling / cooling operation in FIG. 5) in which the second refrigeration cycle sucked in (41) is performed, air conditioning is performed according to the flowchart in FIG. Ability-assisted operation is performed.

Specifically, during the air conditioning capacity assist operation, the controller (100), in step ST11, (1) the second compressor for air conditioning (41) has the maximum frequency, and (2) there is a request for increasing the air conditioning capacity. (3) It is determined whether or not all three conditions that the first compressor for cooling (31) is not at the maximum frequency or air-conditioning priority is satisfied. If these three conditions are satisfied, the cooling capacity of the indoor heat exchanger (93) is insufficient even though the second compressor (41) is at the maximum capacity, and the indoor heat exchanger (93) The cooling capacity is below the cooling load.

Therefore, in this case, the process proceeds to step ST12, and if the first auxiliary heat exchanger (110) is not provided, a part of the refrigerant that will flow to the cold heat exchanger (83) is changed to the first branch. The first pressure reducing valve (116) of the pipe (115) (in the figure, the first pressure reducing valve is indicated as an air conditioning auxiliary expansion valve) is depressurized and evaporated in the first low pressure channel (112), and the first auxiliary suction pipe ( 118) is sucked into the second compressor (41) through the suction relay pipe (58). At this time, the opening of the first pressure reducing valve (116) is adjusted so that the refrigerant pressure in the first low-pressure channel (112) becomes the suction pressure of the second compressor (41). When the first auxiliary suction pipe (118) is connected to the suction port of the second high-stage compression mechanism (41b), the first pressure reducing valve (116) is a refrigerant in the first low-pressure channel (112). The opening degree is adjusted so that the pressure becomes an intermediate pressure of the second compressor (41).

When this operation is performed, the amount of refrigerant sucked in the second compressor (41) can be increased, so that the refrigerant flow rate in the indoor heat exchanger (93) is increased and the cooling capacity is enhanced. Thus, when the condition of step ST11 is satisfied, the air conditioning capability assisting operation (assuming the cooling capability of the indoor heat exchanger (93) using a part of the refrigerant flowing through the first liquid pipe (63) ( First auxiliary operation) is performed. During this operation, the refrigerant is supercooled in the first high-pressure flow path (111), so that a reduction in the capacity of the chilled heat exchanger (83) is suppressed.

When the condition of step ST11 is not satisfied, the operation for increasing the cooling capacity of the indoor heat exchanger (93) is not required, or the cooling capacity of the indoor heat exchanger (93) is set to the operation of the second compressor (41). There is room to increase the frequency. Therefore, in this case, the air conditioning capability auxiliary operation (first auxiliary operation) using the one auxiliary heat exchanger (110) is not performed. Therefore, in this case, the first pressure reducing valve (116) is fully closed in step ST13.

-Effect of Embodiment 1-
In Embodiment 1, in a refrigeration apparatus having a refrigerant circuit (11) in which a plurality of heat exchangers (83, 93) having different evaporation temperatures are connected in parallel to a common heat source heat exchanger (22), the evaporation temperature The first compressor (31) connected to the cold heat exchanger (83) having a low temperature and the second compressor connected to the indoor heat exchanger (93) having a higher evaporation temperature than the first compressor (31) The machine (41) constitutes a compression section (30). Further, the first high-pressure channel (111) and the first low-pressure channel (112) are provided, and the refrigerant flowing through the first high-pressure channel (111) and the refrigerant flowing through the first low-pressure channel (112) are heated. A first auxiliary heat exchanger (110) for exchanging is provided, and the refrigerant outflow side of the first low-pressure channel (112) and the suction portion of the second compressor (41) are connected by the first auxiliary suction pipe (118). is doing.

Therefore, according to the first embodiment, the first refrigeration cycle that sucks the refrigerant evaporated in the cold heat exchanger (83) by the first compressor (31) and the refrigerant evaporated in the indoor heat exchanger (93). The cooling capacity of the indoor heat exchanger (93) is below the cooling load and the cooling capacity is insufficient in the cooling / cooling operation state where the second refrigeration cycle that sucks in the second compressor (41) is performed Then, the air conditioning capability auxiliary operation (first auxiliary operation) can be performed.

Specifically, during the air-conditioning capacity auxiliary operation, if the first auxiliary heat exchanger (110) is not provided, a part of the refrigerant flowing to the cold heat exchanger (83) is the first low-pressure channel. The refrigerant is diverted to (112) and evaporated by exchanging heat with the refrigerant in the first high-pressure channel (111). The evaporated refrigerant is sucked into the second compressor (41) through the first auxiliary suction pipe (118). As a result, the amount of refrigerant sucked into the second compressor (41) can be increased to increase the amount of refrigerant circulating in the indoor heat exchanger (93) having a high evaporation temperature, so that the cooling capacity of the indoor heat exchanger (93) can be increased. .

Thus, conventionally, when the capacity of the indoor heat exchanger (93) having a high evaporation temperature in the cooling / cooling operation state is insufficient, the cooling capacity of the indoor heat exchanger (93) cannot be increased. On the other hand, according to this embodiment, the cooling capacity of the indoor heat exchanger (93) can be increased. Therefore, it becomes possible to cope with a wider range of operating conditions.

In this embodiment, a pressure control valve (V5) whose opening degree can be adjusted between the first suction pipe (32) of the first compressor (31) and the second suction pipe (42) of the second compressor (41). The suction communication pipe (50) provided with is connected.

According to this embodiment, not only the cooling capacity of the indoor heat exchanger (93) is increased, but also part of the refrigerant flowing out of the indoor heat exchanger (93) is reduced in pressure by the pressure regulating valve (V5). Since the compressor (31) can be inhaled, the cooling capacity of the cold heat exchanger (83) can be increased by increasing the refrigerant circulation amount of the cold heat exchanger (83).

In this embodiment, carbon dioxide is used as the refrigerant. For this reason, the influence of global warming can be mitigated.

<< Embodiment 2 >>
Embodiment 2 will be described.

As shown in FIG. 11, Embodiment 2 is an example in which a second auxiliary heat exchanger (120) is further provided in the refrigeration apparatus (10) of Embodiment 1. The second auxiliary heat exchanger (120) is provided in the outdoor unit (20) in order to compensate for the shortage of capacity of the first compressor (31) that sucks and compresses the refrigerant flowing through the cold heat exchanger (83). It has been. That is, the second auxiliary heat exchanger (110) is a heat exchanger for assisting the capacities of the first compressor (31) and the chilled heat exchanger (83).

The second auxiliary heat exchanger (120) has a second high-pressure channel (121) and a second low-pressure channel (122). The second high-pressure channel (121) is connected to the fifth pipe (second liquid pipe) (65). The second low-pressure channel (122) has a refrigerant inflow end connected to a second branch pipe (second branch channel) (125) branched from the third pipe (first liquid pipe) (63). The second branch pipe (125) is provided with a second expansion valve as a second pressure reducing valve (second pressure reducing mechanism) (126). In the second auxiliary heat exchanger (120), heat is exchanged between the refrigerant flowing through the second high-pressure channel (121) and the refrigerant flowing through the second low-pressure channel (122).

A second auxiliary suction pipe (second auxiliary suction flow path) (128) is connected to the refrigerant outflow end of the second low pressure flow path (122). The second auxiliary suction pipe (128) is connected to the suction port of the first low-stage compression mechanism (31a), which is the suction portion of the first compressor (31), via the first suction pipe (32). . The second auxiliary suction pipe (128) may be connected to the suction port of the first high-stage compression mechanism (31b).

The refrigerant circuit (11) of the second embodiment is configured in the same manner as in the first embodiment except that a second auxiliary heat exchanger (120) is added.

-Driving operation-
Also in the second embodiment, the refrigeration apparatus (1) is similar to the first embodiment in the cooling operation, cooling operation, cooling / cooling operation, heating operation, heating / cooling operation, heating / cooling heat recovery operation. Heating / cooling preheating operation and defrosting operation can be performed.

In the second embodiment, in addition to being able to perform the air conditioning capacity auxiliary operation during the cooling / cooling operation, the cooling capacity of the cooling heat exchanger (83) is also insufficient during the cooling / cooling operation of FIG. Can perform the cooling capacity assisting operation according to the flowchart of FIG.

Specifically, during the cooling capacity assist operation, in step ST21, the controller (100) (1) the first compressor (31) for cooling is at the maximum frequency, and (2) the cooling capacity is increased. There is a request, and it is determined whether or not all the three conditions that (3) the second compressor (41) for air conditioning is not at the maximum frequency or the cooling priority is satisfied are satisfied. If these three conditions are satisfied, the cooling capacity of the chilled heat exchanger (83) is insufficient even though the first compressor (31) has the maximum capacity, and the chilled heat exchanger (83 ) Cooling capacity is below the cooling load.

Therefore, in this case, the process proceeds to step ST22, and if the second auxiliary heat exchanger (120) is not provided, a part of the refrigerant that flows to the indoor heat exchanger (93) is removed from the second branch pipe. The second pressure reducing valve (126) of (125) (in the figure, the second pressure reducing valve is indicated as a cooling auxiliary expansion valve) is depressurized and evaporated in the second low pressure flow path (122), and the second auxiliary suction pipe ( 128) to the first compressor (31) through the first suction pipe (32). At this time, the opening of the second pressure reducing valve (126) is adjusted so that the refrigerant pressure in the second low-pressure channel (122) becomes the suction pressure of the first compressor (31). When the second auxiliary suction pipe (128) is connected to the suction port of the first high-stage compression mechanism (31b), the second pressure reducing valve (126) is a refrigerant in the second low-pressure channel (122). The opening degree is adjusted so that the pressure becomes an intermediate pressure of the first compressor (31).

When this operation is performed, the amount of refrigerant sucked in the first compressor (31) can be increased, so that the refrigerant flow rate in the cold heat exchanger (83) increases and the cooling capacity is enhanced. In this way, when the condition of step ST21 is satisfied, the cooling capacity assistance that assists the cooling capacity of the cooling heat exchanger (83) using a part of the refrigerant flowing through the second liquid pipe (65). Operation (second auxiliary operation) is performed. During this operation, the refrigerant is supercooled in the second high-pressure channel (121), so that the capacity reduction of the indoor heat exchanger (93) is suppressed.

When the condition of step ST21 is not satisfied, an operation for increasing the cooling capacity of the chilled heat exchanger (83) is not required, or the cooling capacity of the chilled heat exchanger (83) is set to the first compressor (31). There is room to increase the operating frequency of Therefore, in this case, the cooling capacity auxiliary operation (second auxiliary operation) using the second auxiliary heat exchanger (120) is not performed. Therefore, in this case, the second pressure reducing valve (126) is fully closed in step ST23.

-Effect of Embodiment 2-
In this Embodiment 2, it has the 2nd high pressure channel (121) and the 2nd low pressure channel (122), and flows through the 2nd high pressure channel (121) and the 2nd low pressure channel (122). A second auxiliary heat exchanger (120) for exchanging heat with the refrigerant is provided, and the refrigerant outlet side of the second low-pressure channel (122) and the suction portion of the first compressor (31) are connected to the first auxiliary suction pipe ( 118).

Therefore, according to the second embodiment, in addition to being able to perform the air conditioning capability auxiliary operation of the first embodiment in the cooling / cooling operation state, the cooling capability of the cooling heat exchanger (83) is reduced. When the cooling capacity is insufficient due to a drop in the load, a cooling capacity auxiliary operation (second auxiliary operation) can be performed.

Specifically, during the refrigeration capacity auxiliary operation, if the second auxiliary heat exchanger (120) is not provided, a part of the refrigerant flowing to the indoor heat exchanger (93) is part of the second low-pressure channel. (122) is divided into heat and exchanged with the refrigerant in the second high-pressure channel (121) to evaporate. The evaporated refrigerant is sucked into the first compressor (31) through the second auxiliary suction pipe (128). As a result, the amount of refrigerant sucked into the first compressor (31) can be increased, and the amount of refrigerant circulating in the chilled heat exchanger (93) with a low evaporation temperature can be increased, so the cooling capacity of the indoor heat exchanger (93) is also increased. It is done. As described above, according to the present embodiment, in addition to the air conditioning capacity auxiliary operation, the cooling capacity auxiliary operation can be performed using the second auxiliary heat exchanger (120), so it is possible to cope with a wider range of operating conditions. become.

<< Embodiment 3 >>
In the refrigeration apparatus (10), a heat exchanger (85) that exchanges heat between a heat medium such as water and a refrigerant may be used as the second heat exchanger.

In the refrigeration apparatus (10) of Embodiment 3 shown in FIG. 13, a heat exchanger (85) for generating hot water and cold water is provided instead of the indoor heat exchanger (93) of Embodiment 1. The heat exchanger (85) is connected to the outdoor circuit (21). An expansion valve (86) that functions in the same manner as the indoor expansion valve (92) of the embodiment is connected to the liquid side of the heat exchanger (85). The heat exchanger (85) has a refrigerant channel (85a) and a heat medium channel (85b). In the heat exchanger (85), the refrigerant and the heat medium (water) exchange heat.

When the heat exchanger (85) functions as a radiator, the water in the heat medium channel (85b) is heated by the refrigerant in the refrigerant channel (85a). This water is stored in the tank (87) as hot water. When the heat exchanger (85) functions as an evaporator, the water in the heat medium flow path (85b) is cooled by the refrigerant in the refrigerant flow path (85a). This water is stored in the tank (87) as cold water. Hot water and cold water stored in the tank (87) are supplied to the object by a pump (88).

Also in the third embodiment, the first auxiliary heat exchanger (110) and the second auxiliary heat exchanger (120), which are connected to each other in the same manner as in the second embodiment, are provided. Therefore, since the air conditioning capability assist operation and the cooling capacity assist operation can be performed as in the second embodiment, the same effects as those of the embodiment 2 can be obtained with respect to the air conditioning capability assist and the cooling capacity assist.

<< Other Embodiments >>
In the said embodiment and each modification, it is good also as following structures.

In Embodiments 1 to 3, the first branch pipe (115) is connected to the third pipe (63) (first liquid branch) on the downstream side of the first high-pressure channel (111) of the first auxiliary heat exchanger (110). The pipe may be branched from the pipe (63a) and connected to the refrigerant inflow side of the first low-pressure channel (112) via the first pressure reducing mechanism (116). A first auxiliary suction pipe (118) is connected to the refrigerant outflow side of the first low-pressure channel (112).

In the second and third embodiments, the second branch pipe (125) branches from the fifth pipe (65) on the downstream side of the second high-pressure channel (121) of the second auxiliary heat exchanger (120), and the second branch pipe (125) The structure connected to the refrigerant | coolant inflow side of a 2nd low pressure flow path (122) via a pressure reduction mechanism (126) may be sufficient. A second auxiliary suction pipe (128) is connected to the refrigerant outflow side of the second low-pressure channel (122).

As described above, the first pressure reducing mechanism (116) provided in the first branch pipe (115) and the second pressure reducing mechanism (126) provided in the second branch pipe (125) are the first high pressure channel (111). Or on the upstream side or the downstream side of the second high-pressure channel (121).

The refrigerant in the refrigerant circuit (11) is not limited to carbon dioxide, and other refrigerants such as an HFC refrigerant may be used. The refrigeration cycle may be a so-called critical cycle in which the refrigerant is compressed to a critical pressure or higher, or may be a so-called subcritical cycle in which the refrigerant is compressed to a pressure lower than the critical pressure.

The first compressor (31) and the second compressor (41) may be of a single stage type.

There may be two or more first heat exchangers and two second heat exchangers. The 1st utilization heat exchanger may cool the inside of a freezer, and may be provided in the indoor unit only for cooling.

In the refrigerant circuit (11) of each embodiment, a flow path switching mechanism using a plurality of four-way switching valves or the like may be provided instead of the bridge circuit (70).

The embodiment and the modification have been described above, but various changes in form and details are possible without departing from the spirit and scope of the claims. In addition, the above embodiments and modifications may be appropriately combined or replaced as long as the functions of the subject of the present disclosure are not impaired. The above-mentioned descriptions of “first”, “second”, “third”,... Are used to distinguish the words to which these descriptions are given, and the number and order of the words are also limited. Not what you want.

As described above, the present disclosure is useful for a refrigeration apparatus.

10 Refrigeration equipment 11 Refrigerant circuit 22 Outdoor heat exchanger (heat source heat exchanger)
30 Compressor 31 First compressor 32 First suction pipe (first suction flow path)
41 1st compressor 42 2nd suction pipe (2nd suction flow path)
50 Suction communication pipe (suction communication flow path)
63 Third pipe (first liquid pipe (first liquid flow path))
83 Refrigerated heat exchanger (1st heat exchanger)
93 Indoor heat exchanger (second heat exchanger)
100 controller (control unit)
110 First auxiliary heat exchanger 111 First high-pressure channel 112 First low-pressure channel 115 First branch pipe (first branch channel)
116 First decompression mechanism 118 First auxiliary suction pipe (first auxiliary suction flow path)
120 Second auxiliary heat exchanger 121 Second high pressure flow path 122 Second low pressure flow path 125 Second branch pipe (second branch flow path)
126 Second decompression mechanism 128 Second auxiliary suction pipe (first auxiliary suction flow path)
V5 pressure regulating valve

Claims

A compression section (30), a heat source heat exchanger (22), and a plurality of utilization heat exchangers (83, 93) are provided, and the plurality of utilization heat exchangers (83, 93) are shared heat source heat exchangers (22 ) A refrigerant circuit (11) connected in parallel, and a control unit (100) for controlling the operation of the refrigerant circuit (11),
The plurality of utilization heat exchangers (83, 93) include a first utilization heat exchanger (83) and a second utilization heat exchanger (93),
The compression unit (30) includes a first compressor (31) having a suction unit connected to the first use heat exchanger (83) and a suction unit connected to the second use heat exchanger (93). A second compressor (41),
The refrigerant circuit (11) includes a first auxiliary heat exchanger (110) having a first high-pressure channel (111) and a first low-pressure channel (112), and a refrigerant in the first low-pressure channel (112). A first auxiliary suction channel (118) communicating with the outflow side and the refrigerant suction part of the second compressor (41);
The first auxiliary heat exchanger (110) has the first high-pressure channel (111) connected to a first liquid channel (63) communicating with the first utilization heat exchanger (83), The first low-pressure channel (112) is connected to a first branch channel (115) branched from the first liquid channel (63) and provided with a first pressure reducing mechanism (116). The refrigerant flowing through the high-pressure channel (111) and the refrigerant flowing through the first low-pressure channel (112) are configured to exchange heat,
The refrigerating apparatus, wherein an evaporating temperature of the refrigerant in the first use heat exchanger (83) is lower than an evaporating temperature of the refrigerant in the second use heat exchanger (93).
In claim 1,
A suction communication channel (50) connected to the first suction channel (32) of the first compressor (31) and the second suction channel (42) of the second compressor (41);
A pressure control valve (V5) connected to the suction communication channel (50) and adjustable in opening;
A refrigeration apparatus comprising:
In claim 1 or 2,
The controller (100) includes a first refrigeration cycle for sucking the refrigerant evaporated in the first use heat exchanger (83) through the first compressor (31), and the second use heat exchanger (93). When the cooling capacity of the first use heat exchanger (83) is below the cooling load in the operation state in which the second refrigeration cycle for sucking the refrigerant evaporated in the second compressor (41) is performed, the first The opening of the first pressure reducing mechanism (116) is adjusted so that the refrigerant pressure in the one low-pressure channel (112) becomes the suction pressure or intermediate pressure of the second compressor (41), and the first liquid channel A part of the refrigerant flowing through (63) is supplied from the first branch flow path (115) to the second compressor (41) to assist the cooling capacity of the second utilization heat exchanger (93). A refrigeration apparatus configured to perform auxiliary operation.
In any one of Claims 1-3,
The refrigerant circuit (11) includes a second auxiliary heat exchanger (120) having a second high-pressure channel (121) and a second low-pressure channel (122), and a refrigerant in the second low-pressure channel (122). A second auxiliary suction channel (128) communicating with the outflow side and the refrigerant suction part of the first compressor (31),
The first auxiliary heat exchanger (110) has the second high-pressure channel (121) connected to a second liquid channel (65) communicating with the second utilization heat exchanger (93), The second low-pressure channel (122) branches from the second liquid channel (65) and is connected to a second branch channel (125) provided with a second pressure reducing mechanism (126). A refrigerating apparatus, wherein the refrigerant flowing through the high-pressure channel (121) and the refrigerant flowing through the second low-pressure channel (122) exchange heat.
In claim 4,
The controller (100) includes a first refrigeration cycle for sucking the refrigerant evaporated in the first use heat exchanger (83) through the first compressor (31), and the second use heat exchanger (93). When the cooling capacity of the second heat exchanger (93) is below the cooling load in the operation state in which the second refrigeration cycle for sucking the refrigerant evaporated in the second compressor (41) is performed, 2 The opening of the second pressure reducing mechanism (126) is adjusted so that the refrigerant pressure in the low-pressure channel (122) becomes the suction pressure or intermediate pressure of the first compressor (31), and the second liquid channel (2) supplying a part of the refrigerant flowing through (65) to the first compressor (31) from the second branch flow path (125) to assist the cooling capacity of the first heat exchanger (83). A refrigeration apparatus configured to perform auxiliary operation.