JP2001241789A - Two-refrigerant refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately maintain the feed rate of a high temperature refrigerant to cascade condensers in a two-refrigerant refrigerator with a high temperature refrigerant circuit simplified. SOLUTION: Two refrigerating circuits (50a, 50b) and one cascade circuit (60) are connected in parallel to with an outdoor circuit (30) to constitute the high temperature refrigerant circuit (20), refrigerating units (13a, 13b) respectively house refrigerating evaporators (53a, 53b) of the refrigerating circuits (50a, 50b), an intermediate heat exchanger (66) is connected to the cascade circuit (60) with a cascade expansion valve (61) provided at the upstream of this heat exchanger (66), the opening of the cascade expansion valve (61) is adjusted, based on the outlet refrigerant temperature of the heat exchanger (66), a low temperature refrigerant circuit (70) is connected to the heat exchanger (66), and two refrigerating evaporators (76a, 76b) are parallel connected to the low temperature refrigerant circuit (70) and housed in the refrigerating units (14a, 14b), respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system for performing a binary refrigeration cycle.

[0002]

2. Description of the Related Art Conventionally, there has been known a binary refrigeration system in which a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit are connected via an intermediate heat exchanger which is a cascade condenser to perform a binary refrigeration cycle. This binary refrigeration system includes WO 98/55
As disclosed in Japanese Unexamined Patent Publication No. 809, a refrigerator in which a refrigeration unit is connected to a low-temperature side refrigerant circuit and a refrigeration unit is connected to a high-temperature side refrigerant circuit is known. According to this type of dual refrigerating apparatus, both the freezer and the refrigerator can be cooled by one outdoor unit, so that it is particularly suitable for a convenience store or the like.

[0003] Specifically, a low-temperature side evaporator on the utilization side is provided in the low-temperature side refrigerant circuit of the binary refrigeration apparatus. The intermediate heat exchanger functions as a condenser of the low-temperature side refrigerant circuit. In this low-temperature side refrigerant circuit, the low-temperature side refrigerant circulates while changing its phase, and the refrigerating cycle is performed by repeating the process of compression, condensation, decompression, and evaporation. Then, the refrigerant absorbs heat from the air in the refrigerator in the low-temperature side evaporator, thereby cooling the inside of the refrigerator.

[0004] In the high-temperature side refrigerant circuit of the binary refrigeration apparatus, an intermediate heat exchanger and a high-temperature side evaporator on the utilization side are provided in parallel. In this high-temperature side refrigerant circuit, the high-temperature side refrigerant circulates while changing its phase, and the refrigerating cycle is performed by repeating the process of compression, condensation, decompression, and evaporation. The high-temperature refrigerant flowing into the intermediate heat exchanger absorbs heat from the low-temperature refrigerant and evaporates. The high-temperature-side refrigerant flowing into the high-temperature-side evaporator absorbs heat from the air in the refrigerator and evaporates. Thereby, the inside of the refrigerator is cooled.

[0005]

However, in the high-temperature side refrigerant circuit of the binary refrigeration system, one expansion valve is provided for each of the intermediate heat exchanger and the high-temperature side evaporator.
After the condensed refrigerant is divided, the pressure is reduced at each expansion valve. For this reason, the same number of expansion valves as the intermediate heat exchanger and the high-temperature side evaporator are required, and the configuration becomes complicated,
This has led to higher costs.

In order to solve this problem, a measure is conceived in which only one expansion valve is provided in the high-temperature side refrigerant circuit, the high-temperature side refrigerant is decompressed by this expansion valve, and then distributed to the intermediate heat exchanger and the high-temperature side evaporator. Can be However, in this case, the refrigerant which has been decompressed into a gas-liquid two-phase state must be distributed to the intermediate heat exchanger and the high-temperature side evaporator. Therefore, it becomes difficult to supply an appropriate amount of refrigerant to each of the intermediate heat exchanger and the high-temperature side evaporator. This distribution of the refrigerant becomes more difficult as the number of high-temperature side evaporators increases.

[0007] At this time, the shortage of the supply of the high-temperature side refrigerant to the intermediate heat exchanger is a particular problem. That is, even if the supply amount of the high-temperature side refrigerant to the high-temperature side evaporator is insufficient, the high-temperature side evaporator can cool the inside air to some extent. However, if the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger is insufficient, the high pressure in the low-temperature side refrigerant circuit becomes excessively high, and the cooling operation in the low-temperature side refrigerant circuit is stopped to protect the compressor. For this reason, cooling of the air in the refrigerator in the low-temperature side evaporator is not performed at all, which causes serious problems such as damage to the storage in the refrigerator.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and it is an object of the present invention to secure a supply amount of a high-temperature side refrigerant to an intermediate heat exchanger while simplifying a configuration of a high-temperature side refrigerant circuit. To perform reliable cooling operation.

[0009]

A first solution of the present invention is to provide a high-temperature refrigerant circuit (20) and a low-temperature refrigerant circuit (7).
0) and an intermediate heat exchanger (66).
The binary refrigeration system is intended to perform a binary refrigeration cycle by exchanging heat between the high-temperature side refrigerant of 0) and the low-temperature side refrigerant of the low-temperature side refrigerant circuit (70) in the intermediate heat exchanger (66). The high-temperature side refrigerant circuit (20) has at least one use-side high-temperature side evaporator (53a, 53b) connected in parallel with the intermediate heat exchanger (66), and stores the depressurized refrigerant. In order to distribute the refrigerant to the intermediate heat exchanger (66) and the high-temperature side evaporator (53a, 53b), the amount of refrigerant supplied to the intermediate heat exchanger (66) is adjusted according to the operating conditions. The adjusting means is provided.

According to a second aspect of the present invention, in the first aspect, the adjusting means is provided with an opening provided on the inlet side of the intermediate heat exchanger (66) in the high-temperature side refrigerant circuit (20). It is provided with a variable control valve (61).

According to a third aspect of the present invention, in the above first aspect, the adjusting means is provided on the inlet side of the intermediate heat exchanger (66) in the high-temperature side refrigerant circuit (20) and is connected to each other. A plurality of capillary tubes (64a, 64b) connected in parallel and a switching mechanism (65a, 6b) for changing the number of capillary tubes (64a, 64b) through which the high-temperature-side refrigerant flows.
5b).

According to a fourth aspect of the present invention, in the above first, second or third aspect, the low-temperature side refrigerant circuit (70) includes a plurality of low-temperature side refrigerant circuits connected in parallel to each other. It has a side evaporator (76a, 76b).

In the first solution, the high-temperature side refrigerant circulates while changing the phase in the high-temperature side refrigerant circuit (20), and the low-temperature side refrigerant circulates while changing the phase in the low-temperature side refrigerant circuit (70). I do. In both refrigerant circuits, compression, condensation, expansion,
A cycle consisting of each process of evaporation is repeated, and a vapor compression refrigeration cycle is performed. At that time, in the intermediate heat exchanger (66), the high-temperature side refrigerant and the low-temperature side refrigerant exchange heat with each other. Then, in the intermediate heat exchanger (66), the low-temperature side refrigerant radiates heat and condenses, while the high-temperature side refrigerant absorbs heat and evaporates. That is, the intermediate heat exchanger (66) forms a so-called cascade condenser.

The high-temperature side refrigerant circuit (20) is connected to the intermediate heat exchanger (66) and the high-temperature side evaporators (53a, 53b) on the use side. The intermediate heat exchanger (66) and the high-temperature side evaporator (53a, 53
b) are connected in parallel with each other. The high temperature side refrigerant circuit (20) may be provided with a plurality of high temperature side evaporators (53a, 53b). In this case, each of the high-temperature side evaporators (53a, 53b) and the intermediate heat exchanger (66) are connected to each other in parallel.

In the high-temperature side refrigerant circuit (20), the depressurized high-temperature side refrigerant is supplied to the intermediate heat exchanger (66) and the high-temperature side evaporator (53a, 53).
distributed to b). At that time, the intermediate heat exchanger (66)
, The amount of the high-temperature side refrigerant that matches the operating condition is supplied by the operation of the adjusting means. That is, an appropriate amount of the high-temperature side refrigerant is supplied to the intermediate heat exchanger (66) in the operation state at that time. Therefore, the refrigeration cycle in the low-temperature side refrigerant circuit (70) is reliably performed.

In the second solution, the control means is provided with a control valve (61). The control valve (61) is provided on the inlet side of the intermediate heat exchanger (66) in the high-temperature side refrigerant circuit (20). Therefore, during the cooling operation, the high-temperature side refrigerant is introduced into the intermediate heat exchanger (66) through the control valve (61). The control valve (61) is configured such that its opening can be adjusted. The degree of opening of the control valve (61) is adjusted so that the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger (66) is set to an amount according to the operating conditions. For example, the control valve (61)
The opening is adjusted so that the temperature of the high-temperature side refrigerant flowing out of the intermediate heat exchanger (66) becomes a predetermined value.

In the third solution, the adjusting means is provided with a capillary tube (64a, 64b) and a switching mechanism (65a, 65b). In the adjusting means, a plurality of capillary tubes (64a, 64b) are provided, and each capillary tube (6
4a, 64b) are connected in parallel with each other. The plurality of capillary tubes (64a, 64b) are provided on the inlet side of the intermediate heat exchanger (66) in the high-temperature side refrigerant circuit (20). Therefore, during the cooling operation, the high-temperature side refrigerant is
It is introduced into the intermediate heat exchanger (66) through the capillary tubes (64a, 64b).

The switching mechanism (65a, 65b) is for changing the number of capillary tubes (64a, 64b) through which the high-temperature side refrigerant flows. For example, a capillary tube (64
a, 64b) will be described. In this case, when increasing the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger (66), the high-temperature side refrigerant is caused to flow through both the capillary tubes (64a, 64b) by the switching mechanism (65a, 65b). On the other hand, when reducing the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger (66), the high-temperature side refrigerant is caused to flow through only one of the capillary tubes (64a) by the switching mechanism (65a, 65b). That is, the number of the capillary tubes (64a, 64b) through which the high-temperature side refrigerant flows is changed by the operation of the switching mechanism (65a, 65b), whereby the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger (66) is adjusted to the operating condition. We shall match.

In the fourth solution, the low-temperature side evaporator (76a, 76b) on the use side is provided in the low-temperature side refrigerant circuit (70). The plurality of low-temperature side evaporators (76a, 76b) are provided and connected in parallel with each other. Therefore, in the low-temperature side refrigerant circuit (70), the low-temperature side refrigerant is supplied to each low-temperature side evaporator (76a, 76b).
And evaporates by absorbing heat from the object.

Depending on the operating conditions, the low-temperature side refrigerant is supplied only to some of the low-temperature side evaporators (76a, 76b), and the remaining low-temperature side evaporators (76a, 76b) temporarily cool the object. Sometimes it stops. In this case, the intermediate heat exchanger (6
6) The amount of heat released from the low-temperature refrigerant changes greatly,
The amount of the high-temperature side refrigerant to be supplied to the intermediate heat exchanger (66) also fluctuates greatly. On the other hand, in the present solution, the adjusting means is provided in the high-temperature side refrigerant circuit (20). Therefore, even in such a case, the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger (66) is appropriately maintained.

[0021]

According to the present invention, in the high-temperature side refrigerant circuit (20), the depressurized high-temperature side refrigerant is distributed to the intermediate heat exchanger (66) and the high-temperature side evaporators (53a, 53b). Therefore, only one refrigerant expansion mechanism such as an expansion valve may be provided in the high temperature side refrigerant circuit (20). Therefore, the configuration of the high-temperature side refrigerant circuit (20) can be simplified, the number of components such as the expansion valve and the like can be reduced, and the cost can be reduced.

Further, in the present invention, the high-temperature side refrigerant circuit (20)
An adjusting means is provided for the intermediate heat exchanger (66) so that the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger (66) is maintained at an amount suitable for the operating conditions. Therefore, heat radiation from the low-temperature refrigerant to the high-temperature refrigerant in the intermediate heat exchanger (66) is reliably performed, and the refrigeration cycle operation in the low-temperature refrigerant circuit (70) can be reliably performed.

As a result, according to the present invention, the cooling operation can be reliably performed by appropriately maintaining the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger (66) while simplifying the configuration of the high-temperature side refrigerant circuit (20). Can be performed.

In particular, in the fourth solution, since the low-temperature-side refrigerant circuit (70) is provided with a plurality of low-temperature-side evaporators (76a, 76b), as described above, the intermediate heat exchanger (66) The amount of the high-temperature-side refrigerant to be supplied to the heater may vary greatly. On the other hand, according to the present invention, even when the operating condition changes, the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger (66) can be appropriately maintained by the operation of the adjusting unit. . Therefore, even in such a case, the refrigeration cycle operation in the low-temperature side refrigerant circuit (70) can be reliably performed, and a reliable cooling operation can be performed.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the binary refrigeration apparatus (10) according to the present embodiment is installed in a convenience store to cool a refrigerator and a freezer. This binary refrigeration apparatus (10) includes one outdoor unit (11), one cascade unit (12), two refrigeration units (13a, 13b), and two refrigeration units (14
a, 14b). The outdoor unit (11), the cascade unit (12), the refrigeration units (13a, 13b), and the refrigeration units (14a, 14b) contain various types of equipment. 20) and a low-temperature side refrigerant circuit (70).

The high-temperature side refrigerant circuit (20) includes one outdoor circuit (30), two refrigeration circuits (50a, 50b), and one cascade circuit (60). The outdoor circuit (30) includes a refrigerant distributor (21) and a refrigerant merger (22)
Are connected to the respective refrigeration circuits (50a, 50b) and the cascade circuit (60). In other words, both refrigeration circuits (50a, 50
b) and the cascade circuit (60) are connected in parallel to the outdoor circuit (30).

The outdoor circuit (30) includes a compression mechanism (31)
, An outdoor condenser (33), a receiver (34), a supercooling heat exchanger (44), and an electric expansion valve (36). These compression mechanism (31), outdoor condenser (33), receiver (34), supercooling heat exchanger (44), and electric expansion valve (36)
Is provided in the outdoor unit (11). The degree of opening of the electric expansion valve (36) is adjusted based on the temperature of the refrigerant discharged from the compression mechanism (31), and constitutes a refrigerant expansion mechanism in the high-temperature side refrigerant circuit (20).

The compression mechanism (3) of the high-temperature side refrigerant circuit (20)
1) is configured by connecting two compressors (32) in parallel. The compression mechanism (31) has a variable capacity by changing the number of operating compressors (32).
A check valve (CV) is provided on the discharge side of each compressor (32). The discharge side of the compression mechanism (31), that is, the discharge side of each compressor (32) is connected to the inlet end of the outdoor condenser (33). The suction side of the compression mechanism (31), that is, the suction side of each compressor (32) is connected to the refrigerant merger (22).

The outdoor condenser (33) condenses the refrigerant by heat exchange with outdoor air. An outdoor fan (15) is provided in the outdoor unit (11), and outdoor air is sent to the outdoor condenser (33) by the outdoor fan (15). The outlet end of the outdoor condenser (33) is connected to the receiver (34).

The receiver (34) is connected to an inlet end of the subcooler (35). The subcooler (35) is for cooling the liquid refrigerant sent from the receiver (34) by heat exchange with outdoor air to be in a supercooled state.
The subcooler (35) is formed integrally with the outdoor condenser (33).

The outlet end of the subcooler (35) is connected to one end of the subcooling heat exchanger (44). This supercooling heat exchanger (44) will be described later. Subcooling heat exchanger (4
The other end of 4) is connected to the refrigerant distributor (2) via the electric expansion valve (36).
1) Connected.

The outdoor circuit (30) has a subcooling circuit (4
0) is provided. This subcooling circuit (40) has one end connected between the receiver (34) and the subcooler (35),
The other end is connected between the refrigerant merger (22) and the compression mechanism (31). The supercooling circuit (40) includes a supercooling solenoid valve (41) and a supercooling expansion valve (4
2) and the supercooling heat exchanger (44) are connected. The supercooling expansion valve (42) is constituted by an internal pressure equalizing type temperature-sensitive expansion valve. The temperature-sensitive cylinder (43) of the supercooling expansion valve (42)
It is mounted downstream of the subcooling heat exchanger (44) in the subcooling circuit (40).

The liquid refrigerant that has exited the receiver (34) and has flowed into the subcooling circuit (40) is introduced into the subcooling heat exchanger (44) after being decompressed by the subcooling expansion valve (42). Also,
Liquid refrigerant is sent into the subcooling heat exchanger (44) from the subcooler (35). The subcooling heat exchanger (44) cools the liquid refrigerant flowing from the subcooler (35) toward the electric expansion valve (36) by heat exchange with the refrigerant in the subcooling circuit (40). It is configured.

One end of each refrigeration circuit (50a, 50b) and one end of a cascade circuit (60) are connected to the refrigerant distributor (21). Also, the refrigerant merger (22) includes:
The other end of each refrigeration circuit (50a, 50b) and the cascade circuit (6
0) is connected to the other end (see FIG. 1).

The two refrigeration circuits (50a, 50b) are similarly configured. Each refrigeration circuit (50a, 50b) has a refrigeration solenoid valve (51a, 51b) in order from one end to the other end,
The refrigerating capillary tubes (52a, 52b) and the refrigerating evaporators (53a, 53b) are connected one by one. These two refrigeration circuits (50a, 50b) correspond to the two refrigeration units. That is, the refrigeration solenoid valves (51a, 51b) and the refrigeration capillary tubes (52a, 52b) of each refrigeration circuit (50a, 50b)
The refrigerating evaporator (53a, 53b) is provided in each refrigerating unit (13a, 13b).

The refrigerating evaporators (53a, 53b) evaporate the refrigerant by heat exchange with the air in the refrigerator. The refrigerating evaporators (53a, 53b) constitute a use-side high-temperature evaporator in the high-temperature refrigerant circuit (20).
Each refrigerator unit (13a, 13b) is provided with a refrigerator fan (16a, 16b), and the refrigerator fan (16a, 16b) is provided.
By b), the air in the refrigerator is sent to the refrigeration evaporator (53a, 53b).

The above chilled capillary tubes (52a, 52b)
Is for attaching a resistance corresponding to the cooling capacity of each refrigeration evaporator (53a, 53b). That is, the refrigerated capillary tubes (52a, 52b) are connected to the refrigeration evaporators (53a, 53b).
It is provided in order to make the flow rate of the high-temperature side refrigerant flowing through an appropriate amount.

In the cascade circuit (60), a cascade expansion valve (61) and an intermediate heat exchanger (66) are connected in order from one end to the other end. The cascade circuit (60) is connected to the first passage (67) of the intermediate heat exchanger (66). The cascade circuit (60) is provided with a cascade solenoid valve (63) in parallel with the cascade expansion valve (61).

The cascade expansion valve (61) is constituted by an internal pressure equalizing type temperature-sensitive expansion valve. The temperature-sensitive cylinder (62) of the cascade expansion valve (61) is attached to the cascade circuit (60) downstream of the intermediate heat exchanger (66).
The cascade expansion valve (61) is a control valve whose opening is variable, and constitutes a control means.

The low temperature side refrigerant circuit (70) includes a compressor (71), an intermediate heat exchanger (66), a receiver (72),
Low-temperature expansion valve (73) and two refrigeration evaporators (76a, 76
b) and the accumulator (79) are connected.
Among them, the compressor (71), the intermediate heat exchanger (66), the receiver (72), the low-temperature side expansion valve (73), and the accumulator (79) are provided in the cascade unit (12).

In the low-temperature side refrigerant circuit (70), the discharge side of the compression 2 is connected to the intermediate heat exchanger (66) via a check valve (CV). Specifically, it is connected to the inlet end of the second passage (68) in the intermediate heat exchanger (66). The outlet end of the second passage (68) in the intermediate heat exchanger (66) is connected to the low temperature side expansion valve (73) via a receiver.

The low-temperature side expansion valve (73) is a refrigeration solenoid valve (77a,
It is connected to each freezing evaporator (76a, 76b) via a freezing capillary tube (78a, 78b). Refrigeration solenoid valve (77a, 77b) and refrigeration capillary tube (78a, 7
8b) is provided on the inlet side of each freezing evaporator (76a, 76b). That is, the low-temperature side refrigerant flowing from the low-temperature side expansion valve (73) toward the refrigeration evaporator (76a, 76b) passes through the refrigeration solenoid valves (77a, 77b), and then flows through the refrigeration capillary tubes (78a, 78b). Through the freezer evaporator (76
a, 76b). The outlet end of each refrigerating evaporator (76a, 76b) is connected to the suction side of the compressor (71) via an accumulator (79).

The intermediate heat exchanger (66) is connected to the first passage (6
The heat exchange between the high-temperature side refrigerant of 7) and the low-temperature side refrigerant of the second passage (68) is performed. During cooling operation,
The intermediate heat exchanger (66) functions as an evaporator of the high-temperature side refrigerant circuit (20) and at the same time functions as a condenser of the low-temperature side refrigerant circuit (70). That is, the intermediate heat exchanger (66) forms a so-called cascade condenser.

The low temperature side expansion valve (73) is constituted by an external pressure equalizing type temperature sensitive expansion valve. Cold side expansion valve (7
The temperature-sensitive cylinder (74) of (3) is attached to the low-temperature side refrigerant circuit (70) downstream of both refrigeration evaporators (76a, 76b). The equalizing pipe (75) of the low-temperature side expansion valve (73) is connected to both refrigeration evaporators (76a, 76) in the low-temperature side refrigerant circuit (70).
b) is connected downstream.

The freezing evaporators (76a, 76b) evaporate the refrigerant by heat exchange with the air in the freezer. The refrigerating evaporators (76a, 76b) constitute a use-side low-temperature evaporator in the low-temperature refrigerant circuit (70).
The refrigeration evaporator (76a, 76b) is provided with a refrigeration solenoid valve (77a, 7b).
7b) and frozen capillary tubes (78a, 78b)
The refrigeration units (14a, 14b) are provided. That is, each refrigeration unit (14a, 14b) has a refrigeration evaporator (76a, 76b).
b), one freezing solenoid valve (77a, 77b) and one freezing capillary tube (78a, 78b) are provided. In addition, each refrigeration unit (14a, 14b) has a fan (17
a, 17b) are provided one by one. This freezer fan (1
7a and 17b), the air in the freezer is sent to the freezing evaporator (76a and 76b).

The above-mentioned frozen capillary tube (78a, 78b)
Is for attaching a resistance corresponding to the cooling capacity of each freezing evaporator (76a, 76b). That is, the freezing capillary tubes (78a, 78b) are connected to the respective freezing evaporators (76a, 76b).
It is provided in order to make the flow rate of the low-temperature side refrigerant flowing through an appropriate amount.

-Operation- An operation during the cooling operation of the binary refrigeration system (10) will be described.

In the high temperature side refrigerant circuit (20), the electric expansion valve (36) is adjusted to a predetermined opening. When both compressors (32) of the compression mechanism (31) are operated in this state, the high-temperature side refrigerant circulates in the high-temperature side refrigerant circuit (20), and a refrigeration cycle is performed.

Specifically, the high-temperature side refrigerant discharged from the compression mechanism (31) is sent to the outdoor condenser (33). In the outdoor condenser (33), the refrigerant radiates heat and condenses by heat exchange with the outdoor air. The refrigerant condensed in the outdoor condenser (33)
Flow into receiver. The liquid refrigerant flowing out of the receiver is
A part thereof flows into the subcooling circuit (40), and the rest is sent to the subcooler (35).

The liquid refrigerant flowing into the subcooler (35) of the outdoor condenser (33) is further cooled by exchanging heat with outdoor air to be in a supercooled state. The supercooled refrigerant is sent from the subcooler (35) to the subcooling heat exchanger (44). On the other hand, the liquid refrigerant flowing into the supercooling circuit (40) passes through the supercooling electromagnetic valve (41), is depressurized by the supercooling expansion valve (42), and is sent to the supercooling heat exchanger (44).

In the subcooling heat exchanger (44), the subcooler (3
The liquid refrigerant sent from 5) and the gas-liquid two-phase refrigerant sent through the supercooling circuit (40) exchange heat. Then, the liquid refrigerant from the subcooler (35) radiates heat to increase the degree of supercooling. On the other hand, the refrigerant in the supercooling circuit (40) absorbs heat and evaporates, and is sent to the suction side of the compression mechanism (31). The subcooling expansion valve (42) is a subcooling heat exchanger (44)
The degree of opening of the refrigerant is adjusted based on the temperature of the refrigerant returned to the compression mechanism (31) through the supercooling circuit (40).

The liquid refrigerant supercooled by the supercooling heat exchanger (44) is sent to the refrigerant distributor (21) after being decompressed by the electric expansion valve (36). The refrigerant entering the refrigerant distributor (21)
It is divided into three directions and flows into two refrigeration circuits (50a, 50b) and one cascade circuit (60).

The refrigerant flowing into the first refrigeration circuit (50a) is supplied to the refrigeration solenoid valve (51a) and the refrigeration capillary tube (5a).
Through 2a), it flows into the refrigeration evaporator (53a). In the refrigerating evaporator (53a), the inflowing refrigerant absorbs heat from the air in the refrigerator and evaporates. Thereby, the inside air is cooled. The refrigerant evaporated in the refrigeration evaporator (53a) flows into the refrigerant merger (22). The above operation is the same for the second refrigeration circuit (50b). That is, the refrigerant flowing into the second refrigeration circuit (50b) is supplied to the refrigeration evaporator (53b).
And flows into the refrigerant merger (22) after absorbing heat and evaporating.

The high-temperature side refrigerant flowing into the cascade circuit (60) flows through the cascade expansion valve (61) into the first passage (67) of the intermediate heat exchanger (66). Intermediate heat exchanger (6
In the first passage (67) of (6), the inflowing high-temperature side refrigerant flows into the second passage (67).
The refrigerant absorbs heat from the low-temperature side refrigerant in the passage (68) and evaporates. The evaporated high-temperature side refrigerant is sent to the refrigerant merger (22).

At this time, the amount of the high-temperature side refrigerant flowing into the cascade circuit (60) is adjusted by changing the opening of the cascade expansion valve (61). In the first passage (67) of the intermediate heat exchanger (66), the amount of refrigerant that can be evaporated in the first passage (67), that is, the amount of heat released from the low-temperature side refrigerant in the intermediate heat exchanger (66) is provided. A corresponding amount of the high-temperature side refrigerant is supplied.

The cascade solenoid valve (63) of the cascade circuit (60) is opened, for example, several minutes before the start of the compressor (71) of the low-temperature side refrigerant circuit (70). When the cascade solenoid valve (63) is opened, regardless of the opening degree of the cascade expansion valve (61), the first passage (67) of the intermediate heat exchanger (66)
The high-temperature side refrigerant is introduced into the air. As a result, the intermediate heat exchanger (66) is pre-cooled, and the compressor (7
After starting 1), the cascade expansion valve (61) is set to an appropriate opening degree in a short time.

As described above, the refrigerant evaporated in the first passage (67) of the refrigerating evaporator (53a, 53b) and the intermediate heat exchanger (66) is fed into the refrigerant merger (22). . The refrigerant merged in the refrigerant merger (22) is sent to the suction side of the compression mechanism (31). And this refrigerant is compressed by a compression mechanism (31).
Is sucked into the compressor (32) and compressed, and this circulation is repeated.

In the low-temperature side refrigerant circuit (70), the compressor (71)
Is operated, the low-temperature side refrigerant circulates in the low-temperature side refrigerant circuit (70), and the refrigeration cycle operation is performed. Specifically, in the low-temperature side refrigerant circuit (70), the low-temperature side refrigerant discharged from the compressor (71) is sent to the second passage (68) of the intermediate heat exchanger (66). In the second passage (68) of the intermediate heat exchanger (66),
The low-temperature side refrigerant radiates heat to the high-temperature side refrigerant in the first passage (67) and condenses. The condensed refrigerant once flows into the receiver (72). The liquid refrigerant flowing out of the receiver (72) is decompressed by the low-temperature side expansion valve (73), then divided into two parts, and sent to the refrigerating evaporators (76a, 76b).

The refrigerant sent to the first refrigeration evaporator (76a) flows into the refrigeration evaporator (76a) through the refrigeration solenoid valve (77a) and the refrigeration capillary tube (78a). First
In the refrigerating evaporator (76a), the inflowing refrigerant absorbs heat from the air in the freezer and evaporates. Thereby, the inside air is cooled. The refrigerant evaporated in the first freezing evaporator (76a) flows to the accumulator (79). The above operation is the same for the second refrigerating evaporator (76b). That is, the refrigerant that has flowed into the second freezing evaporator (76b) absorbs heat and evaporates, and then flows to the accumulator (79). The refrigerant evaporated by the two refrigerating evaporators (76a, 76b) and flowing into the accumulator (79) is then sucked into the compressor (71), compressed, and repeats this circulation.

For example, when only the first refrigeration unit (13a) is turned off, the refrigeration solenoid valve (51a) of the first refrigeration circuit (50a) is closed. In this case, the high-temperature side refrigerant flowing into the refrigerant distributor (21) is supplied to the second refrigeration circuit (50).
b) and the cascade circuit (60). Therefore,
The amount of the high-temperature side refrigerant flowing into the cascade circuit (60) increases. Then, the inflow of the high-temperature side refrigerant is excessive with respect to the amount of refrigerant that can be evaporated in the first passage (67) of the intermediate heat exchanger (66), and the temperature of the high-temperature side refrigerant flowing out of the first passage (67) is increased. Decrease. On the other hand, as the temperature of the high-temperature side refrigerant at the outlet of the intermediate heat exchanger (66) decreases, the cascade expansion valve (6
The opening of 1) is narrowed. Therefore, the cascade circuit (6
The inflow amount of the high-temperature side refrigerant with respect to 0) is reduced.

When only the first refrigeration unit (14a) is turned off, the refrigeration solenoid valve (77a) provided in the first refrigeration unit (14a) is closed. in this case,
Only in the refrigerating evaporator (76b) provided in the second refrigerating unit (14b), the low-temperature side refrigerant absorbs heat. Then, the heat radiation amount of the low-temperature side refrigerant in the intermediate heat exchanger (66) decreases, and also in this case, the first passage (6) of the intermediate heat exchanger (66)
The inflow amount of the high-temperature side refrigerant becomes excessive with respect to the refrigerant amount that can be evaporated in the step 7). Accordingly, the temperature of the high-temperature side refrigerant at the outlet of the intermediate heat exchanger (66) decreases, and accordingly, the opening of the cascade expansion valve (61) is reduced, so that the amount of the high-temperature side refrigerant flowing into the cascade circuit (60) is reduced. Be reduced.

On the other hand, when the first refrigeration unit returns from the thermo-off and starts the cooling operation, the refrigeration solenoid valve (77a) provided in the first refrigeration unit (14a) is opened. In this case, the low-temperature side refrigerant is supplied to both refrigeration evaporators (76
a, 76b). And the intermediate heat exchanger (6
The heat radiation amount of the low-temperature side refrigerant in 6) increases, and the inflow amount of the high-temperature side refrigerant is smaller than the refrigerant amount that can be evaporated in the first passage (67) of the intermediate heat exchanger (66). Therefore, the temperature of the high-temperature side refrigerant at the outlet of the intermediate heat exchanger (66) increases, and accordingly, the opening of the cascade expansion valve (61) is increased. Therefore, the amount of the high-temperature side refrigerant flowing into the cascade circuit (60) increases.

-Effects of the Embodiment- In this embodiment, in the high-temperature side refrigerant circuit (20), the high-temperature side refrigerant is decompressed by the electric expansion valve (36) and then introduced into the refrigerant distributor (21). (50a, 50b) and the cascade circuit (60). Therefore, as the refrigerant expansion mechanism in the high-temperature side refrigerant circuit (20), only one electric expansion valve (36) needs to be provided. Therefore, the configuration of the high-temperature side refrigerant circuit (20) can be simplified, the number of components can be reduced, and the cost can be reduced.

Further, in this embodiment, the cascade expansion valve (6) is connected to the cascade circuit (60) of the high-temperature side refrigerant circuit (20).
1) is provided so that the supply amount of the high-temperature side refrigerant to the intermediate heat exchanger (66) is maintained at an amount suitable for the operating conditions. Therefore, heat radiation from the low-temperature refrigerant to the high-temperature refrigerant in the intermediate heat exchanger (66) is reliably performed, and the refrigeration cycle in the low-temperature refrigerant circuit (70) can be reliably performed.

As a result, according to the present embodiment, the configuration of the intermediate heat exchanger (6) is simplified while simplifying the configuration of the high-temperature side refrigerant circuit (20).
It is possible to perform a reliable cooling operation by appropriately maintaining the supply amount of the high-temperature side refrigerant to 6).

Particularly, in the present embodiment, the refrigeration unit (13a,
13b) and a plurality of refrigeration units (14a, 14b). Each refrigeration unit (13a, 13b) and each refrigeration unit (14a, 14b) are individually thermo-on.
Since / off is performed, the amount of the high-temperature side refrigerant to be supplied to the intermediate heat exchanger (66) may vary greatly. On the other hand, in the present embodiment, the amount of the high-temperature side refrigerant supplied to the intermediate heat exchanger (66) can be adjusted by adjusting the opening of the cascade expansion valve (61). Therefore, even if the operating conditions change due to the thermo-on / off of the refrigeration units (13a, 13b) and the refrigeration units (14a, 14b), the intermediate heat exchanger ( It is possible to appropriately maintain the supply amount of the high-temperature side refrigerant to 66). As a result, the refrigeration cycle in the low-temperature side refrigerant circuit (70) can be reliably performed, and a reliable cooling operation can be performed.

[0068]

In the above embodiment, the cascade expansion valve (61) is provided in the cascade circuit (60) of the high-temperature side refrigerant circuit (20), and the cascade expansion valve (61) constitutes adjusting means. However, instead of this, the adjusting means may be configured as follows.

Specifically, the cascade circuit (60) is provided with two capillary tubes (64a, 64b) and two solenoid valves (65a, 65b) instead of the cascade expansion valve (61).
As shown in FIG. 3, these capillary tubes (64a,
64b) and the solenoid valves (65a, 65b) are the intermediate heat exchanger (66) and the refrigerant distributor (21) in the cascade circuit (60).
It is provided between.

The first capillary tube (64a) and the second capillary tube (64b) are connected in parallel with each other. Further, a first solenoid valve (65a) is provided immediately before the first capillary tube (64a), and a second solenoid valve (65b) is provided immediately before the second capillary tube (64b). Further, a temperature sensor (Th) is attached downstream of the intermediate heat exchanger (66) in the cascade circuit (60). Then, the second solenoid valve (65b) is opened and closed based on the temperature detected by the temperature sensor (Th). The first solenoid valve (65a) and the second solenoid valve (65b) constitute a switching mechanism.

For example, when only the first refrigeration unit (13a) is turned off, the refrigeration solenoid valve (51a) of the first refrigeration circuit (50a) is closed. In this case, the high-temperature side refrigerant flowing into the refrigerant distributor (21) is supplied to the second refrigeration circuit (50).
b) and the cascade circuit (60). Therefore,
The amount of the high-temperature side refrigerant flowing into the cascade circuit (60) increases. Then, the inflow of the high-temperature side refrigerant is excessive with respect to the amount of refrigerant that can be evaporated in the first passage (67) of the intermediate heat exchanger (66), and the temperature of the high-temperature side refrigerant flowing out of the first passage (67) is increased. Decrease. Accordingly, when the temperature detected by the temperature sensor (Th) becomes lower than the predetermined value, the second solenoid valve (65b) is closed. Therefore, the high-temperature side refrigerant sent to the intermediate heat exchanger (66) flows only through the first capillary tube (64a), and the amount of refrigerant introduced into the first passage (67) of the intermediate heat exchanger (66) Is reduced.

When only the first refrigeration unit (14a) is turned off, the refrigeration solenoid valve (77a) provided in the first refrigeration unit (14a) is closed. in this case,
Only in the refrigerating evaporator (76b) provided in the second refrigerating unit (14b), the low-temperature side refrigerant absorbs heat. Then, the heat radiation amount of the low-temperature side refrigerant in the intermediate heat exchanger (66) decreases, and also in this case, the first passage (6) of the intermediate heat exchanger (66)
The inflow amount of the high-temperature side refrigerant becomes excessive with respect to the refrigerant amount that can be evaporated in the step 7). Therefore, the temperature of the high-temperature side refrigerant at the outlet of the intermediate heat exchanger (66) decreases. Accordingly, when the temperature detected by the temperature sensor (Th) becomes lower than the predetermined value, the second solenoid valve (65b) is closed. For this reason, the intermediate heat exchanger (6
The high-temperature side refrigerant sent to 6) is the first capillary tube (6
4a), the amount of refrigerant introduced into the first passage (67) of the intermediate heat exchanger (66) is reduced.

On the other hand, when the first refrigeration unit (14a) returns from thermo-off and starts the cooling operation, the refrigeration solenoid valve (77a) provided in the first refrigeration unit (14a) is opened. In this case, the low-temperature side refrigerant absorbs heat in both refrigeration evaporators (76a, 76b). Then, the heat radiation amount of the low-temperature side refrigerant in the intermediate heat exchanger (66) increases, and the inflow amount of the high-temperature side refrigerant is larger than the refrigerant amount that can be evaporated in the first passage (67) of the intermediate heat exchanger (66). It will be too small. Therefore, the temperature of the high-temperature side refrigerant at the outlet of the intermediate heat exchanger (66) rises. Accordingly, when the temperature detected by the temperature sensor (Th) becomes equal to or higher than a predetermined value, the second solenoid valve (65b) is opened. Therefore, the high-temperature side refrigerant sent to the intermediate heat exchanger (66) flows through both the first and second capillary tubes (64b), and is introduced into the first passage (67) of the intermediate heat exchanger (66). The amount of refrigerant to be increased increases.

[Brief description of the drawings]

FIG. 1 is a piping diagram showing a part of a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit according to a first embodiment.

FIG. 2 is a piping diagram illustrating a part of a high-temperature side refrigerant circuit according to the first embodiment.

FIG. 3 is a piping diagram illustrating a part of a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit according to another embodiment.

[Explanation of symbols]

 (20) High-temperature side refrigerant circuit (53a, 53b) Refrigerating evaporator (high-temperature side evaporator) (61) Cascade expansion valve (control valve) (64a) First capillary tube (64b) Second capillary tube (65a) No. 1 Solenoid valve (switching mechanism) (65b) 2nd solenoid valve (switching mechanism) (66) Intermediate heat exchanger (70) Low-temperature refrigerant circuit (76a, 76b) Refrigeration evaporator (low-temperature evaporator)

Continuing on the front page (72) Inventor Eye ▲ Saki ▼ Joji 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries Inside the Kanaoka Plant of Sakai Seisakusho Co., Ltd. (72) Masaaki Takegami 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries 3L045 AA03 BA01 CA02 DA02 EA01 FA02 GA07 HA07 JA13 PA05

Claims (4)

[Claims] 1. A high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit of a high-temperature side refrigerant circuit (20), comprising a high-temperature side refrigerant circuit (20), a low-temperature side refrigerant circuit (70) and an intermediate heat exchanger (66). A high-temperature side refrigerant circuit (20), wherein the low-temperature side refrigerant exchanges heat with an intermediate heat exchanger (66) to perform a two-stage refrigeration cycle. At least one use-side high-temperature evaporator (53a, 53b) connected in parallel is provided, and the decompressed refrigerant is supplied to the intermediate heat exchanger (66) and the high-temperature evaporator (53a, 53b).
And a regulating unit for regulating the amount of refrigerant supplied to the intermediate heat exchanger (66) according to operating conditions. 2. The two-way refrigeration system according to claim 1, wherein the adjusting means comprises a variable opening control valve (61) provided on the inlet side of the intermediate heat exchanger (66) in the high-temperature side refrigerant circuit (20). )
A binary refrigeration system comprising: 3. The two-way refrigeration system according to claim 1, wherein the adjusting means is provided on an inlet side of the intermediate heat exchanger (66) in the high-temperature side refrigerant circuit (20) and is connected in parallel with each other. A binary refrigeration apparatus including a capillary tube (64a, 64b) and a switching mechanism (65a, 65b) for changing the number of capillary tubes (64a, 64b) through which the high-temperature side refrigerant flows. 4. The binary refrigeration system according to claim 1, wherein the low-temperature side refrigerant circuit (70) includes a plurality of use-side low-temperature side evaporators (76a, 76b) connected in parallel with each other. Equipped binary refrigeration equipment.