JP7469583B2 - air conditioner - Google Patents

Description

Refrigerant cycle system with cascade heat exchanger.

Patent document 1 (JP 2014-74508 A) discloses a refrigerant cycle system with a cascade heat exchanger.

There may be a difference between the amount of refrigerant required by the refrigerant cycle system in heating operation and the amount of refrigerant required by the refrigerant cycle system in cooling operation. This difference is caused by the difference between the volume of the cascade heat exchanger and the volume of the utilization heat exchanger. If the difference is large, the refrigerant cycle system must store a large amount of refrigerant for the operation that requires more refrigerant, either heating operation or cooling operation. However, there is a demand to reduce the amount of refrigerant charged to the refrigerant cycle system.

The refrigerant cycle system of the first aspect includes a primary cycle for circulating a first fluid, a secondary cycle for circulating a second fluid, and a cascade heat exchanger having a first fluid passage and a second fluid passage configured to perform heat exchange between the first fluid and the second fluid. The second fluid is a refrigerant. The secondary cycle includes a secondary heat exchanger for utilizing the cold or hot heat that the second fluid obtains from the cascade heat exchanger, a pressure reducing device for reducing the pressure of the second fluid, and a switching device for switching the direction of circulation of the second fluid. The first volume V1, which is the volume of the secondary heat exchanger, and the second volume V2, which is the volume of the second fluid passage of the cascade heat exchanger,

This is the relationship.

With this configuration, the first volume V1 and the second volume V2 do not differ significantly. Therefore, the amount of refrigerant required by the refrigerant cycle system does not differ significantly between cooling operation, in which a large amount of liquid refrigerant exists in the second fluid passage of the cascade heat exchanger, and heating operation, in which a large amount of liquid refrigerant exists in the secondary heat exchanger. This allows the amount of refrigerant to be reduced.

The refrigerant cycle system of the second aspect is the refrigerant cycle system of the first aspect, in which the first volume V1 and the second volume V2 are

This is the relationship.

This configuration allows for even less refrigerant to be filled into the refrigerant cycle system.

The refrigerant cycle system of the third aspect is the refrigerant cycle system of the first or second aspect, in which the secondary heat exchanger has a flat multi-hole tube.

The refrigerant cycle system of the fourth aspect is a refrigerant cycle system according to any one of the first aspect to the third aspect, and includes a plurality of secondary cycles and a plurality of cascade heat exchangers. The first volume is the sum of the volumes of the plurality of secondary heat exchangers. The second volume is the sum of the volumes of the plurality of second fluid passages included in the plurality of cascade heat exchangers.

The refrigerant cycle system of the fifth aspect is the refrigerant cycle system of the fourth aspect, in which the multiple secondary cycles have a heat exchanger with flat multi-hole tubes and a cross-fin heat exchanger.

1 is a diagram showing a refrigerant cycle system 100 according to a first embodiment. FIG. 1 is a diagram showing a refrigerant cycle system 100 according to a modified example 1A of the first embodiment. FIG. 1 is a diagram showing a refrigeration cycle system 100' according to a second embodiment.

First Embodiment
(1) Overall Configuration Fig. 1 shows a refrigerant cycle system 100. The refrigerant cycle system 100 is for obtaining cold or hot heat from a heat source and providing the cold or hot heat to a user.

The refrigeration cycle system 100 has one heat source unit 10, one cascade unit 30, and one utilization unit 50.

The primary cycle 20 is formed by connecting the heat source unit 10 and the cascade unit 30. The primary cycle 20 is a circuit that circulates a first fluid. The first fluid is a refrigerant.

The secondary cycle 40 is formed by connecting the cascade unit 30 and the utilization unit 50. The secondary cycle 40 is a circuit that circulates a second fluid. The second fluid is a refrigerant. The first fluid and the second fluid may be the same refrigerant or different refrigerants.

(2) Detailed Configuration (2-1) Heat Source Unit 10
The heat source unit 10 obtains cold or hot heat from the outside air, which is a heat source. The heat source unit 10 includes a compressor 11, a four-way switching valve 12, a heat source heat exchanger 13, a heat source expansion valve 14, a subcooling expansion valve 15, a subcooling heat exchanger 16, a liquid stop valve 18, and a gas stop valve 19.

The compressor 11 sucks in a low-pressure gas refrigerant, which is the first fluid, compresses it, and discharges a high-pressure gas refrigerant. The four-way switching valve 12 makes the connection shown by the solid lines in FIG. 1 during cooling operation, and makes the connection shown by the dashed lines in FIG. 1 during heating operation. The heat source heat exchanger 13 exchanges heat between the first fluid and the outside air. The heat source heat exchanger 13 functions as a condenser during cooling operation, and as an evaporator during heating operation. The heat source expansion valve 14 adjusts the flow rate of the first fluid. Furthermore, the heat source expansion valve 14 functions as a pressure reducing device that reduces the pressure of the first fluid.

The subcooling expansion valve 15 reduces the pressure of the circulating first fluid to produce a cooling gas. The subcooling heat exchanger 16 provides a degree of subcooling to the first fluid by exchanging heat between the circulating first fluid and the cooling gas.

The liquid shutoff valve 18 and the gas shutoff valve 19 shut off the flow path through which the first fluid circulates, for example, during installation work for the heat source unit 10.

(2-2) Cascade unit 30
The cascade unit 30 is for performing heat exchange between the first fluid and the second fluid.

The cascade unit 30 has a primary expansion valve 31, a secondary expansion valve 32, a compressor 33, a four-way switching valve 34, a cascade heat exchanger 35, a liquid shutoff valve 38, and a gas shutoff valve 39.

The primary expansion valve 31 adjusts the amount of the first fluid circulating through the primary cycle 20. Furthermore, the primary expansion valve 31 reduces the pressure of the first fluid.

The secondary expansion valve 32 adjusts the amount of the second fluid circulating through the secondary cycle 40. Furthermore, the secondary expansion valve 32 reduces the pressure of the second fluid.

The compressor 33 draws in the low-pressure gas refrigerant, which is the second fluid, compresses it, and discharges the high-pressure gas refrigerant. The four-way switching valve 34 functions as a switching device, making the connection shown by the solid lines in FIG. 1 during cooling operation, and the connection shown by the dashed lines in FIG. 1 during heating operation.

The cascade heat exchanger 35 exchanges heat between a first fluid and a second fluid. The cascade heat exchanger 35 is, for example, a plate heat exchanger. The cascade heat exchanger 35 has a first fluid passage 351 and a second fluid passage 352. The first fluid passage 351 allows the first fluid to pass through. The second fluid passage 352 allows the second fluid to pass through. The cascade heat exchanger 35 functions as an evaporator for the first fluid and a condenser for the second fluid during cooling operation, and functions as an evaporator for the first fluid and a condenser for the second fluid during heating operation.

The liquid shutoff valve 38 and the gas shutoff valve 39 shut off the flow path through which the second fluid circulates, for example, during installation work for the cascade unit 30.

(2-3) Utilization unit 50
The utilization unit 50 is for providing cold or hot heat to a user. The utilization unit 50 has a utilization heat exchanger 51 and a utilization expansion valve 52. The utilization heat exchanger 51 is for allowing the user to utilize the cold or hot heat. The utilization heat exchanger 51 is a microchannel heat exchanger and has a flat multi-hole tube. The flat multi-hole tube has a refrigerant flow path with a hole diameter of, for example, 0.05 mm or more and 2.0 mm or less. The utilization expansion valve 52 adjusts the amount of the second fluid circulating through the secondary cycle 40. Furthermore, the utilization expansion valve 52 functions as a pressure reducing device for reducing the pressure of the second fluid.

(3) Operation (3-1) Cooling Operation (3-1-1) Operation of the Primary Cycle 20 The compressor 11 sucks in low-pressure gas refrigerant, which is a first fluid, and discharges high-pressure gas refrigerant. The high-pressure gas refrigerant reaches the heat source heat exchanger 13 via the four-way switching valve 12. The heat source heat exchanger 13 condenses the high-pressure gas refrigerant, thereby producing high-pressure liquid refrigerant. At this time, the refrigerant, which is the first fluid, releases heat to the outside air. The high-pressure liquid refrigerant passes through the heat source expansion valve 14, which is fully opened, passes through the subcooling heat exchanger 16, and reaches the primary side expansion valve 31 via the liquid stop valve 18. The primary side expansion valve 31, which is set to an appropriate opening degree, reduces the pressure of the high-pressure liquid refrigerant, thereby producing a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant enters the first fluid passage 351 of the cascade heat exchanger 35. The cascade heat exchanger 35 evaporates the low-pressure gas-liquid two-phase refrigerant, thereby producing a low-pressure gas refrigerant. At this time, the first fluid absorbs heat from the second fluid. The low-pressure gas refrigerant leaves the first fluid passage 351, passes through the gas stop valve 19, and is sucked into the compressor 11 via the four-way selector valve 12.

A portion of the high-pressure liquid refrigerant that leaves the heat source expansion valve 14 is decompressed by the subcooling expansion valve 15, which is set to an appropriate opening degree, and becomes a two-phase gas-liquid cooling gas. The cooling gas passes through the subcooling heat exchanger 16. At this time, the cooling gas provides a degree of subcooling by cooling the high-pressure liquid refrigerant. The cooling gas leaves the subcooling heat exchanger 16, mixes with the low-pressure gas refrigerant coming from the four-way switching valve 12, and is sucked into the compressor 11.

(3-1-2) Operation of the secondary cycle 40 The compressor 33 sucks in low-pressure gas refrigerant, which is the second fluid, and discharges high-pressure gas refrigerant. The high-pressure gas refrigerant passes through the four-way switching valve 34 and enters the second fluid passage 352 of the cascade heat exchanger 35. The cascade heat exchanger 35 condenses the high-pressure gas refrigerant, thereby producing high-pressure liquid refrigerant. At this time, the second fluid releases heat to the first fluid. The high-pressure liquid refrigerant leaves the second fluid passage 352, passes through the liquid stop valve 38, and reaches the secondary expansion valve 32. The secondary expansion valve 32, which has an appropriate opening, reduces the pressure of the high-pressure liquid refrigerant, thereby producing a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant reaches the utilization expansion valve 52. The utilization expansion valve, which has an appropriate opening, further reduces the pressure of the low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant reaches the utilization heat exchanger 51. The utilization heat exchanger 51 evaporates the low-pressure gas-liquid two-phase refrigerant, thereby producing a low-pressure gas refrigerant. At this time, the second fluid refrigerant absorbs heat from the environment in which the user is located. The low-pressure gas refrigerant leaves the utilization heat exchanger 51, passes through the gas shutoff valve 39, and is sucked into the compressor 33 via the four-way switching valve 12.

(3-2) Heating Operation (3-2-1) Operation of the Primary Cycle 20 The compressor 11 sucks in low-pressure gas refrigerant, which is a first fluid, and discharges high-pressure gas refrigerant. The high-pressure gas refrigerant passes through the four-way switching valve 12, the gas stop valve 19, and enters the first fluid passage 351 of the cascade heat exchanger 35. The cascade heat exchanger 35 condenses the high-pressure gas refrigerant, thereby producing high-pressure liquid refrigerant. At this time, the first fluid releases heat to the second fluid. The high-pressure liquid refrigerant passes through the fully opened primary expansion valve 31, then passes through the liquid stop valve 18 and the subcooling heat exchanger 16, and reaches the heat source expansion valve 14. The heat source expansion valve 14, which is set to an appropriate opening degree, reduces the pressure of the high-pressure liquid refrigerant, thereby producing a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant reaches the heat source heat exchanger 13. The heat source heat exchanger 13 evaporates the low-pressure gas-liquid two-phase refrigerant, thereby producing a low-pressure gas refrigerant. At this time, the refrigerant, which is the first fluid, absorbs heat from the outside air. The low-pressure gas refrigerant passes through the four-way switching valve 12 and is drawn into the compressor 11.

(3-2-2) Operation of the Secondary Cycle 40 The compressor 33 sucks in low-pressure gas refrigerant, which is the second fluid, and discharges high-pressure gas refrigerant. The high-pressure gas refrigerant passes through the four-way switching valve 34, the gas stop valve 39, and reaches the utilization heat exchanger 51. The utilization heat exchanger 51 condenses the high-pressure gas refrigerant, thereby producing high-pressure liquid refrigerant. At this time, the refrigerant, which is the second fluid, releases heat to the environment in which the user is present. The high-pressure liquid refrigerant reaches the utilization expansion valve 52. The utilization expansion valve 52, which has an appropriate opening, reduces the pressure of the high-pressure liquid refrigerant, thereby producing a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant passes through the liquid stop valve 38 and reaches the secondary expansion valve 32. The secondary expansion valve 32, which has an appropriate opening, further reduces the pressure of the low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant enters the second fluid passage 352 of the cascade heat exchanger 35. The cascade heat exchanger 35 evaporates the low-pressure gas-liquid two-phase refrigerant, thereby producing a low-pressure gas refrigerant. At this time, the second fluid absorbs heat from the first fluid. The low-pressure gas refrigerant leaves the second fluid passage 352, passes through the four-way switching valve 34, and is sucked into the compressor 33.

(4) Specifications of the Heat Exchanger The volume of the utilization heat exchanger 51 is a first volume V1. The volume of the second fluid passage 352 of the cascade heat exchanger 35 is a second volume V2. The first volume V1 and the second volume V2 are

This is the relationship.

Preferably, the first volume V1 and the second volume V2 are:

This is the relationship.

(5) Features (5-1)
The first volume V1 and the second volume V2 are

This is the relationship.

In this case, the first volume V1 and the second volume V2 do not differ greatly. Therefore, the amount of refrigerant required by the refrigerant cycle system 100 does not differ greatly between cooling operation, in which a large amount of liquid refrigerant is present in the second fluid passage 352 of the cascade heat exchanger 35, and heating operation, in which a large amount of liquid refrigerant is present in the utilization heat exchanger 51. Therefore, the amount of refrigerant charged into the refrigerant cycle system 100 can be reduced. In addition, the refrigerant cycle system 100 is unlikely to require a storage container for the second fluid.

(5-2)
The first volume V1 and the second volume V2 are

The relationship may be as follows.

In this case, the difference between the first volume V1 and the second volume V2 is even smaller. Therefore, the amount of refrigerant filled into the refrigerant cycle system 100 can be further reduced.

(6) Modifications (6-1) Modification 1A
2 shows a configuration of a refrigeration cycle system 100 according to a modification 1A of the above-described embodiment. In this modification, the first fluid is water or brine. The first fluid is circulated through a primary cycle 20 by a pump 11a instead of the compressor 11.

In this modified example, the volume of the utilization heat exchanger 51 is the first volume V1. The volume of the second fluid passage 352 of the cascade heat exchanger 35 is the second volume V2. The first volume V1 and the second volume V2 are:

This is the relationship.

This configuration also reduces the amount of refrigerant filled into the refrigerant cycle system 100.

Preferably, the first volume V1 and the second volume V2 are:

This is the relationship.

This configuration also allows the amount of refrigerant filled into the refrigerant cycle system 100 to be further reduced.

(6-2) Modification 1B
In the above embodiment, the number of utilization units 50 is one. Alternatively, the number of utilization units may be two or more. In this case, the first volume V1 in the above formula is the sum of the volumes of the utilization heat exchangers of all the utilization units.

Second Embodiment
(1) Overall Configuration Fig. 3 shows a refrigeration cycle system 100'. The refrigeration cycle system 100' differs from the first embodiment in having one heat source unit 10, two cascade units 30A and 30B, and four utilization units 50A, 50B, 50C, and 50D.

The primary cycle 20 is formed by connecting the heat source unit 10 and the cascade units 30A and 30B. The primary cycle 20 is a circuit that circulates a first fluid. The first fluid is a refrigerant.

A secondary cycle 40A is formed by connecting the cascade unit 30A and the utilization units 50A and 50B. Another secondary cycle 40B is formed by connecting the cascade unit 30B and the utilization units 50C and 50D. The secondary cycles 40A and 40B are circuits that circulate a second fluid. The second fluid is a refrigerant. The first fluid and the second fluid may be the same refrigerant or different refrigerants.

(2) Detailed Configuration (2-1) Heat Source Unit 10
The heat source unit 10 has a similar configuration to the heat source unit 10 of the first embodiment.

(2-2) Cascade units 30A, 30B
The cascade units 30A and 30B have a similar configuration to the cascade unit 30 of the first embodiment.

The first cascade unit 30A has a cascade heat exchanger 35. The volume of the second fluid passage 352 of this cascade heat exchanger 35 is V21.

The second cascade unit 30B has a cascade heat exchanger 35. The volume of the second fluid passage 352 of this cascade heat exchanger 35 is V22. Here, the second volume V2, which is the sum of the volumes of the second fluid passages 352 of all the cascade heat exchangers 35, is

It is.

(2-3) Utilization units 50A, 50B, 50C, 50D
The utilization units 50A, 50B, 50C, and 50D have a similar configuration to the utilization unit 50A of the first embodiment.

The first utilization unit 50A has a utilization heat exchanger 51. The volume of this utilization heat exchanger 51 is V11.

The second utilization unit 50B has a utilization heat exchanger 51. The volume of this utilization heat exchanger 51 is V12.

The third utilization unit 50C has a utilization heat exchanger 51. The volume of this utilization heat exchanger 51 is V13.

The fourth utilization unit 50D has a utilization heat exchanger 51. The volume of this utilization heat exchanger 51 is V14.

Here, the first volume V1, which is the sum of the volumes of all the utilization heat exchangers 51, is:

It is.

(3) Specifications of Heat Exchanger (3-1) First Secondary Cycle 40A
The volume of the heat exchanger is designed so that the following relationship holds:

Preferably, the volume of the heat exchanger is designed so that the following relationship holds:

(3-2) Second secondary cycle 40B
The volume of the heat exchanger is designed so that the following relationship holds:

Preferably, the volume of the heat exchanger is designed so that the following relationship holds:

(3-3) Entire Refrigeration Cycle System 100′ The volume of the heat exchanger is designed so that the following relationship holds:

Preferably, the volume of the heat exchanger is designed so that the following relationship holds:

(4) Characteristics In the second embodiment, the volume of the heat exchanger is designed so that the following relationship holds:

Preferably, the volume of the heat exchanger is designed so that the following relationship holds:

In this case, the first volume V1 and the second volume V2 do not differ significantly. Therefore, the amount of refrigerant required by the refrigerant cycle system 100' does not differ significantly between cooling operation, in which a large amount of liquid refrigerant is present in the second fluid passage 352 of the cascade heat exchanger 35, and heating operation, in which a large amount of liquid refrigerant is present in the utilization heat exchanger 51. Therefore, the refrigerant cycle system 100' is unlikely to require a storage container for the second fluid.

(5) Modifications (5-1) Modification 2A
In the above embodiment, the number of cascade units 30A, 30B is two. Alternatively, the number of cascade units may be three or more.

(5-2) Modification 2B
In the above embodiment, the four utilization heat exchangers 51 of the utilization units 50A, 50B, 50C, and 50D have flat multi-hole tubes as in the first embodiment. Alternatively, some of the four utilization heat exchangers 51 may have flat multi-hole tubes, and some of the four utilization heat exchangers 51 may be cross-fin heat exchangers.

(5-3) Modification 2C
Each of the modified examples of the first embodiment may be applied to the second embodiment.

<Conclusion>
Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure described in the claims.

10: Heat source unit 20: Primary cycle 30: Cascade unit 30A: Cascade unit 30B: Cascade unit 34: Four-way switching valve (switching device)
35: Cascade heat exchanger 40: Secondary cycle 40A: Secondary cycle 40B: Secondary cycle 50: Utilization unit 50A: Utilization unit 50B: Utilization unit 50C: Utilization unit 50D: Utilization unit 51: Utilization heat exchanger (secondary heat exchanger)
52: Utilization expansion valve (pressure reducing device)
100: refrigerant cycle system 100': refrigerant cycle system 351: first fluid passage 352: second fluid passage V1: first volume V2: second volume

JP 2014-74508 A

Claims (5)

A heat source unit (10);
a cascade unit (30) that can be connected to the heat source unit;
a utilization unit (50) connectable to the cascade unit;
Equipped with
a primary side cycle (20) for circulating a first refrigerant;
a secondary cycle (40) for circulating a second refrigerant;
A refrigerant cycle system (100) forming
The heat source unit is
a first compressor (11) for compressing the first refrigerant;
having
The cascade unit comprises:
A second compressor (33) that compresses the second refrigerant;
A switching device (34) for switching the direction of circulation of the second refrigerant ;
a cascade heat exchanger (35) having a first refrigerant passage (351) and a second refrigerant passage (352) configured to perform heat exchange between the first refrigerant and the second refrigerant ;
having
The cascade heat exchanger is a plate heat exchanger,
The utilization unit includes:
a secondary heat exchanger (51) having a refrigerant flow path through which the second refrigerant passes and for utilizing the cold or hot heat that the second refrigerant obtains from the cascade heat exchanger;
having
The secondary heat exchanger is a microchannel heat exchanger;
A first volume V1 which is a volume of the refrigerant passage of the secondary heat exchanger, and a second volume V2 which is a volume of the second refrigerant passage of the cascade heat exchanger,

The relationship is
A refrigerant cycle system (100). The first volume V1 and the second volume V2,

The relationship is
The refrigerant cycle system according to claim 1 . The secondary heat exchanger has a flat multi-hole tube.
The refrigeration cycle system according to claim 1 or 2. A plurality of the secondary cycles (40A, 40B);
a plurality of said cascade heat exchangers;
Equipped with
The first volume V1 is a sum of the volumes of the multiple secondary side heat exchangers,
The second volume V2 is a sum of the volumes of the second refrigerant passages included in the multiple cascade heat exchangers.
A refrigerant cycle system (100') according to any one of claims 1 to 3. The secondary cycles each include a heat exchanger having a flat multi-hole tube and a cross-fin heat exchanger.
The refrigerant cycle system according to claim 4.

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