EP4752462A1

EP4752462A1 - Refrigeration cycle device

Info

Publication number: EP4752462A1
Application number: EP25739692.9A
Authority: EP
Inventors: Kei Takenaka; Kanoko TSUKA; Shun Yoshioka; Shouta AGOU
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2024-09-26
Filing date: 2025-04-24
Publication date: 2026-06-03
Also published as: WO2026069802A1; JP2026059652A; EP4752462A4

Abstract

A refrigeration cycle apparatus (100) includes a heat source heat exchanger (13) and a bridge circuit (40). The heat source heat exchanger (13) includes a refrigerant inlet pipe (13a), a refrigerant outlet pipe (13b), a plurality of refrigerant paths (61), a diverger (50), and a converger (70). The bridge circuit (40) always causes a refrigerant (R) to flow into the heat source heat exchanger (13) at the refrigerant inlet pipe (13a) and flow out of the heat source heat exchanger (13) at the refrigerant outlet pipe (13b). The plurality of refrigerant paths (61) is connected to a plurality of diverger pipes (56) of the diverger (50) and a plurality of converger pipes (75) of the converger (70). The number of the diverger pipes (56) is smaller than the number of the converger pipes (75).

Description

TECHNICAL FIELD

The present disclosure relates to a refrigeration cycle apparatus including a heat exchanger that handles a non-azeotropic mixed refrigerant and achieves therein a counterflow in which a traveling direction of air faces a traveling direction of the non-azeotropic mixed refrigerant.

BACKGROUND ART

A refrigeration cycle apparatus disclosed in Patent Literature 1 ( JP 2009-222362 A ) includes a bridge circuit. Such a bridge circuit may be mounted on a refrigeration cycle apparatus that handles a non-azeotropic mixed refrigerant. In this case, the bridge circuit functions to always keep the same traveling direction of a refrigerant flowing through a heat source heat exchanger regardless of which one of a cold heat utilization operation and a hot heat utilization operation the refrigeration cycle apparatus executes, and thus achieves a counterflow of the heat source heat exchanger.

SUMMARY OF THE INVENTION

A heat exchanger may be provided with a diverger. The diverger is often installed at a refrigerant inlet of a heat exchanger used as an evaporator. The diverger distributes a low-pressure gas-liquid two-phase refrigerant flowing into the refrigerant inlet to a plurality of refrigerant paths of the heat exchanger to make uniform the evaporation of the low-pressure gas-liquid two-phase refrigerant in the heat exchanger.
When the heat exchanger that always achieves a counterflow functions as a condenser, the diverger diverges a high-pressure gas refrigerant flowing from the refrigerant inlet into a plurality of refrigerant paths. In general, a gas refrigerant is subject to a large pressure loss from a pipe. Therefore, the plurality of diverger pipes that guides the high-pressure gas refrigerant after being diverged need to be designed to be thick in order to reduce the pressure loss.
However, when the heat exchanger functions as an evaporator, the low-pressure gas-liquid two-phase refrigerant containing a heavy liquid component cannot obtain a sufficient speed when passing through a plurality of thick diverger pipes. Therefore, the low-pressure gas-liquid two-phase refrigerant may not be able to reach the refrigerant path at a high position from a diverger body disposed at a low position.

A refrigeration cycle apparatus according to a first aspect includes a four-way switching valve, a first heat exchanger, a second heat exchanger, and a refrigerant rectifier. The four-way switching valve switches between a first operation and a second operation. The first heat exchanger includes a refrigerant inlet pipe and a refrigerant outlet pipe. The first heat exchanger functions as a condenser in the first operation and functions as an evaporator in the second operation. The second heat exchanger functions as an evaporator in the first operation and functions as a condenser in the second operation. The refrigerant rectifier causes a refrigerant to flow into the first heat exchanger at the refrigerant inlet pipe and flow out of the first heat exchanger at the refrigerant outlet pipe in both the first operation and the second operation. The first heat exchanger further includes a heat exchanger body, a diverger, and a converger. The heat exchanger body includes a plurality of refrigerant paths through which the refrigerant passes. The diverger diverges the refrigerant into the plurality of refrigerant paths. The converger converges the refrigerant from the plurality of refrigerant paths. The diverger includes a diverger body and a diverger pipe. The diverger body has one intake port and a plurality of exhaust ports. The one intake port is connected to the refrigerant inlet pipe. The plurality of diverger pipes connect the plurality of exhaust ports and the plurality of refrigerant paths, respectively. The converger includes a plurality of converger pipes and a converger body. The plurality of converger pipes is connected to the plurality of refrigerant paths. The converger body is connected to all of the plurality of converger pipes and the refrigerant outlet pipe. The number of the plurality of diverger pipes is smaller than the number of the plurality of converger pipes.
In this configuration, the number of the diverger pipes is smaller than the number of the converger pipes. Therefore, since the number of the diverger pipes is small, each diverger pipe can be thick in a limited space in the apparatus. As a result, the resistance received by the refrigerant from the diverger pipes can be reduced.
A refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, in which the plurality of refrigerant paths includes a lowest path and a highest path. The lowest path is disposed at a height that is lowest. The highest path is disposed at a height that is highest. The height of the plurality of exhaust ports is all lower than the height of the lowest path.
In this configuration, the height of the exhaust port is lower than the height of the lowest path. Even when the diverger pipe extending from the diverger body to each refrigerant path inlet is long as described above, the refrigerant flowing through the diverger pipe does not receive a large resistance. Therefore, the refrigerant can flow upward in the diverger pipe.
A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the first or second aspect, in which the number of the plurality of diverger pipes is smaller than or equal to a half of the number of the plurality of converger pipes.
In this configuration, the number of the diverger pipes is smaller than a half of the number of the converger pipes. Therefore, the thickness of the converger pipe can be effectively set large, and the refrigerant flowing through the diverger pipe does not receive a large resistance. Therefore, the refrigerant can flow upward in the diverger pipe.
A refrigeration cycle apparatus according to a fourth aspect is the refrigeration cycle apparatus according to any one of the first to third aspects, in which each of the plurality of refrigerant paths includes a heat transfer tube. An inner diameter of all of the plurality of diverger pipes is 80% or more and 120% or less of an inner diameter of the heat transfer tube.
In this configuration, the inner diameter of each diverger pipe is 80% or more and 120% or less of the inner diameter of the heat transfer tube. Therefore, since the inner diameter of the diverger pipe is large, the refrigerant flowing through the diverger pipe does not receive a large resistance.
A refrigeration cycle apparatus according to a fifth aspect is the refrigeration cycle apparatus according to any one of the first to fourth aspects, in which the heat exchanger body includes a plurality of refrigerant path inlets and a plurality of branch portions. The plurality of refrigerant path inlets is a portion through which the refrigerant flows into the plurality of refrigerant paths. The plurality of branch portions is provided at any of the plurality of refrigerant path inlets. Each of the plurality of branch portions connects one of the plurality of diverger pipes and at least two of the plurality of refrigerant path inlets.
In this configuration, the refrigerant coming from the diverger pipe is distributed to at least two refrigerant path inlets at the branch portion. Therefore, the refrigerant can be supplied to a large number of refrigerant paths while the resistance of the diverger pipe is kept small.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a refrigeration cycle apparatus 100 according to a first embodiment.
FIG. 2 is a schematic diagram showing a configuration of a heat source heat exchanger 13.
FIG. 3 is a schematic diagram showing a configuration of a heat exchanger body 60.
FIG. 4 is a schematic diagram showing a counterflow between a refrigerant R and an air flow AF in the heat source heat exchanger 13.
FIG. 5 is a graph showing temperature changes of the refrigerant R and the air flow AF in a cold heat utilization operation.
FIG. 6 is a graph showing temperature changes of the refrigerant R and the air flow AF in a hot heat utilization operation.
FIG. 7 is a schematic diagram showing a detailed structure in the heat source heat exchanger 13.
FIG. 8 is a schematic diagram showing a refrigeration cycle apparatus 100A according to a second embodiment.
FIG. 9 is a schematic diagram showing a refrigeration cycle apparatus 100B according to a third embodiment.

DESCRIPTION OF EMBODIMENTS

(1) Overall configuration

FIG. 1 shows a configuration of refrigeration cycle apparatus 100 according to a first embodiment. The refrigeration cycle apparatus 100 provides cold heat or hot heat acquired from a heat source to a user by circulating a refrigerant R. The refrigeration cycle apparatus 100 provides cold heat to the user in a cold heat utilization operation. The refrigeration cycle apparatus 100 provides cold heat to the user in a hot heat utilization operation. The refrigeration cycle apparatus 100 can be configured as an air conditioner, a refrigerator, a freezer, a water heater, a floor heating device, or the like. When the refrigeration cycle apparatus 100 is an air conditioner, the cold heat utilization operation and the hot heat utilization operation correspond to a cooling operation and a heating operation, respectively. The refrigeration cycle apparatus 100 includes a heat source unit 10, a utilization unit 20, and a connection pipe group 30.

(2) Detailed configuration

(2-1) Refrigerant R

The refrigerant R is a non-azeotropic mixed refrigerant. The non-azeotropic mixed refrigerant is a refrigerant produced by mixing a plurality of refrigerant components having different boiling points. The refrigerant R is, for example, R454C. R454C is a mixture of R32 and R1234yf.
The non-azeotropic mixed refrigerant shows a remarkable temperature glide. The temperature glide is a range of temperature change appearing in a process in which the refrigerant R evaporates or condenses. In the process in which the non-azeotropic mixed refrigerant evaporates, a low-boiling-point component evaporates first, and then a high-boiling-point component evaporates later. In the process in which the non-azeotropic mixed refrigerant condenses, a high-boiling-point component condenses first, and then a low-boiling-point component condenses later. The presence of a plurality of boiling points as described above causes a large temperature glide.

(2-2) Heat source unit 10

The heat source unit 10 acquires cold heat or hot heat from 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 fan 14, a bridge circuit 40, a heat source expansion valve 15, an accumulator 16, a liquid shutoff valve 17, and a gas shutoff valve 18.

(2-2-1) Compressor 11

The compressor 11 includes a suction pipe 11a and a discharge pipe 11b. The compressor 11 sucks the refrigerant R in a low-pressure gas state from the suction pipe 11a, compresses the refrigerant R, and discharges the refrigerant R in a high-pressure gas state from the discharge pipe 11b.

(2-2-2) Four-way switching valve 12

The four-way switching valve 12 switches between the cold heat utilization operation and the hot heat utilization operation by switching a traveling direction of the refrigerant R. When the cold heat utilization operation is performed, the four-way switching valve 12 achieves the connection indicated by the solid line in FIG. 1 and causes the refrigerant R to proceed in the direction indicated by an arrow CO. When the hot heat utilization operation is performed, the four-way switching valve 12 achieves the connection indicated by the broken line in FIG. 1 and causes the refrigerant R to proceed in the direction indicated by an arrow HO.

(2-2-3) Heat source heat exchanger 13 and heat source fan 14

(2-2-3-1) Functions

The heat source heat exchanger 13 causes the refrigerant R to acquire cold heat or hot heat by performing heat exchange between air, which is a heat source, and the refrigerant R. When the cold heat utilization operation is performed, the heat source heat exchanger 13 functions as a condenser or a heat radiator for the refrigerant R, and causes the refrigerant R to acquire cold heat. When the hot heat utilization operation is performed, the heat source heat exchanger 13 functions as an evaporator or a heat absorber of the refrigerant R, and causes the refrigerant R to acquire hot heat.
The heat source heat exchanger 13 includes a refrigerant inlet pipe 13a and a refrigerant outlet pipe 13b. The refrigerant R enters the heat source heat exchanger 13 at the refrigerant inlet pipe 13a and exits from the heat source heat exchanger 13 at the refrigerant outlet pipe 13b. The heat source fan 14 generates an air flow passing through the heat source heat exchanger 13 to promote heat exchange between air and the refrigerant R.
Hereinafter, the term "condenser" can include use as a heat radiator without phase transition of the refrigerant R, and the term "evaporator" can include use as a heat absorber without phase transition of the refrigerant R.

(2-2-3-2) Structure

FIG. 2 shows a structure of the heat source heat exchanger 13. The heat source heat exchanger 13 includes a diverger 50, a heat exchanger body 60, and a converger 70 in addition to the refrigerant inlet pipe 13a and the refrigerant outlet pipe 13b.
The diverger 50 includes a diverger body 51 to which the refrigerant inlet pipe 13a is connected, and a plurality of diverger pipes 56 extending from the diverger body 51. The diverger body 51 has one intake port 53 and a plurality of exhaust ports 54. The refrigerant inlet pipe 13a is connected to the intake port 53. The plurality of diverger pipes 56 is respectively connected to the exhaust ports 54. The refrigerant R flowing into the refrigerant inlet pipe 13a is diverged into the plurality of diverger pipes 56.
The heat exchanger body 60 is a portion that performs heat exchange between the refrigerant R and air. The heat exchanger body 60 has a plurality of refrigerant paths 61 through which the refrigerant R flows. The plurality of refrigerant paths 61 include a lowest path 61L disposed at the lowest height and a highest path 61H disposed at the highest height. Each of the refrigerant paths 61 has a refrigerant path inlet 62 and a refrigerant path outlet 63. The refrigerant path inlet 62 is a portion through which the refrigerant R flows into the refrigerant path 61. The refrigerant path outlet 63 is a portion through which the refrigerant R flows out of the refrigerant path 61. The plurality of refrigerant path inlets 62 is connected to the diverger pipes 56 via the plurality of branch portions 64. The plurality of branch portions 64 will be described later.
The converger 70 includes a plurality of converger pipes 75 and a converger body 76. Each of the converger pipes 75 connects one refrigerant path outlet 63 and the converger body 76. The converger body 76 has an outlet pipe connecting portion 77 to which the refrigerant outlet pipe 13b is connected. The converger 70 converges the refrigerant R received from the plurality of refrigerant paths 61 and exhausts the refrigerant R to the refrigerant outlet pipe 13b. The number of the plurality of diverger pipes 56 is smaller than the number of the plurality of converger pipes 75. The number of the diverger pipes 56 is preferably smaller than a half of the number of the converger pipes 75.
FIG. 3 shows a configuration of the heat exchanger body 60. The heat exchanger body 60 includes a plurality of heat transfer tubes 65 and a plurality of fins 67. Each of the heat transfer tubes 65 is inserted into through holes of all the fins 67. Ends of two adjacent heat transfer tubes 65 are connected by a U-shaped tube 66. One refrigerant path 61 includes a plurality of heat transfer tubes 65 and a plurality of U-shaped tubes 66. An inner diameter of all of the plurality of diverger pipes 56 included in the diverger 50 is smaller than 80% or more and 120% or less of an inner diameter of the heat transfer tube 65.

(2-2-3-3) Counterflow

FIG. 4 schematically shows a counterflow achieved in the heat source heat exchanger 13 and the heat source fan 14. The counterflow means that the traveling direction of the refrigerant R is opposite to the traveling direction of the air flow AF. Achieving a counterflow in the heat source heat exchanger 13 is important for heat exchange of the refrigerant R having a large temperature glide.
The refrigerant R flows into the heat source heat exchanger 13 from the refrigerant inlet pipe 13a, is diverged by the diverger 50, passes through the plurality of refrigerant paths 61, converges at the converger 70, and flows out of the heat source heat exchanger 13 from the refrigerant outlet pipe 13b. Each of the refrigerant paths 61 has a plurality of heat transfer tubes 65, and includes the heat transfer tubes 65 arranged in a first row L1 closer to a fin front end 671 of the heat source heat exchanger 13 and the heat transfer tubes 65 arranged in a second row L2 closer to a fin rear end 672. After flowing in from the refrigerant inlet pipe 13a, the refrigerant R always first passes through the heat transfer tubes 65 in the first row L1, then passes through the heat transfer tubes 65 in the second row L2, and finally flows out from the refrigerant outlet pipe 13b. In other words, the refrigerant R travels in -y direction from the fin front end 671 toward the fin rear end 672.
On the other hand, the air flow AF generated by the heat source fan 14 passes between the adjacent fins 67 while traveling in +y direction from the fin rear end 672 toward the fin front end 671.

(2-2-4) Bridge circuit 40

Referring to FIG. 1 again, the bridge circuit 40 is used for always achieving a counterflow between the refrigerant R and the air flow AF in the heat source heat exchanger 13. Normally, in a refrigerant circuit without the bridge circuit 40, the direction of the refrigerant R flowing through the heat exchanger is reversed every time the cold heat utilization operation and the hot heat utilization operation are switched. In contrast, in the refrigeration cycle apparatus 100 according to the present embodiment, the bridge circuit 40 always keeps the same traveling direction of the refrigerant R in the heat source heat exchanger 13 regardless of which one of the cold heat utilization operation and the hot heat utilization operation is executed. The bridge circuit 40 causes the refrigerant R to always enter the heat source heat exchanger 13 through the refrigerant inlet pipe 13a and always exit the heat source heat exchanger 13 through the refrigerant outlet pipe 13b regardless of which one of the direction indicated by the arrow CO and the direction indicated by the arrow HO the traveling direction of the refrigerant R is.
The bridge circuit 40 includes a first node A, a second node B, a third node C, and a fourth node D. The first node A is connected to the refrigerant outlet pipe 13b. The second node B is connected to the compressor 11 via the four-way switching valve 12. The third node C is connected to the refrigerant inlet pipe 13a. The fourth node D is connected to the heat source expansion valve 15.
The bridge circuit 40 further includes a first flow path AB extending from the first node A to the second node B, a second flow path BC extending from the second node B to the third node C, a third flow path DC extending from the fourth node D to the third node C, and a fourth flow path AD extending from the first node A to the fourth node D.
The bridge circuit 40 includes a first check valve 41, a second check valve 42, a third check valve 43, and a fourth check valve 44. These check valves keep the same traveling direction of the refrigerant R in the flow paths where it is installed and prevent backflow of the refrigerant R. The first check valve 41 is provided in the first flow path AB and allows the refrigerant R to flow only in a direction from the first node A toward the second node B. The second check valve 42 is provided in the second flow path BC, and allows the refrigerant R to flow only in a direction from the second node B toward the third node C. The third check valve 43 is provided in the third flow path DC, and allows the refrigerant R to flow only in a direction from the fourth node D toward the third node C. The fourth check valve 44 is provided in the fourth flow path AD, and allows the refrigerant R to flow only in a direction from the first node A toward the fourth node D.

(2-2-5) Heat source expansion valve 15

The heat source expansion valve 15 decompresses the refrigerant R. The heat source expansion valve 15 includes an electric valve having an adjustable opening degree. When the opening degree of the heat source expansion valve 15 is set small, the amount of the refrigerant R that can pass through the heat source expansion valve 15 decreases, and the pressure of the refrigerant R after passing through the heat source expansion valve 15 decreases.

(2-2-6) Accumulator 16

The accumulator 16 stores only a liquid component contained in the refrigerant R therein to allow only a gas component to pass therethrough. The accumulator 16 is connected to the suction pipe 11a of the compressor 11, and restrains the liquid component of the refrigerant R from damaging the compressor 11.

(2-2-7) Liquid shutoff valve 17 and gas shutoff valve 18

The liquid shutoff valve 17 and the gas shutoff valve 18 are used for manually shutting off movement of the refrigerant R. The liquid shutoff valve 17 and the gas shutoff valve 18 are manually opened or closed by an installation operator of the refrigeration cycle apparatus 100.

(2-3) Utilization unit 20

The utilization unit 20 provides the user with cold heat or hot heat acquired from the heat source by the heat source unit 10. The utilization unit 20 includes a utilization heat exchanger 23 and a utilization fan 24.

(2-3-1) Utilization heat exchanger 23

The utilization heat exchanger 23 provides cold heat or hot heat to the user by performing heat exchange between the refrigerant R and air in an environment where the user is present or water used by the user. When the cold heat utilization operation is performed, the utilization heat exchanger 23 functions as an evaporator of the refrigerant R and provides cold heat to the user. When the hot heat utilization operation is performed, the utilization heat exchanger 23 functions as a condenser of the refrigerant R and provides hot heat to the user. As described above, here, the term "condenser" can include use as a heat radiator without phase transition of the refrigerant R, and the term "evaporator" can include use as a heat absorber without phase transition of the refrigerant R.

(2-3-2) Utilization fan 24

The utilization fan 24 is provided in the case where the user uses cold heat or hot heat via air. The utilization fan 24 generates an air flow passing through the utilization heat exchanger 23 to promote heat exchange between air and the refrigerant R.

(2-4) Connection pipe group 30

The connection pipe group 30 connects the heat source unit 10 and the utilization unit 20 to constitute a circulation path of the refrigerant R. The connection pipe group 30 includes a liquid connection pipe 31 and a gas connection pipe 32. The liquid connection pipe 31 mainly allows the refrigerant R in a liquid state or a gas-liquid two-phase state to pass therethrough. The liquid connection pipe 31 connects the liquid shutoff valve 17 and the utilization heat exchanger 23. The gas connection pipe 32 mainly allows the refrigerant R in the high-pressure gas state or the low-pressure gas state to pass therethrough. The gas connection pipe 32 connects the gas shutoff valve 18 and the utilization heat exchanger 23.

(3) Overall operation

(3-1) Cold heat utilization operation

When the cold heat utilization operation is performed, the four-way switching valve 12 achieves the connection indicated by the solid line in FIG. 1 and causes the refrigerant R to proceed in the direction indicated by an arrow CO.
The compressor 11 sucks the refrigerant R in the low-pressure gas state from the suction pipe 11a, and discharges the refrigerant R in the high-pressure gas state from the discharge pipe 11b. The refrigerant R in the high-pressure gas state passes through the four-way switching valve 12 and reaches the second node B of the bridge circuit 40. Thereafter, the refrigerant R passes through the second check valve 42 and reaches the third node C. The refrigerant R then enters the heat source heat exchanger 13 at the refrigerant inlet pipe 13a. The heat source heat exchanger 13 condenses the refrigerant R by using cold heat of air to generate the refrigerant R in a high-pressure liquid state. The refrigerant R in the high-pressure liquid state flows out of the heat source heat exchanger 13 through the refrigerant outlet pipe 13b and then reaches the first node A. Thereafter, the refrigerant R passes through the fourth check valve 44 and reaches the fourth node D. After that, the refrigerant R in the high-pressure liquid state is decompressed by the heat source expansion valve 15 to become the refrigerant R in the gas-liquid two-phase state. Thereafter, the refrigerant R passes through the liquid shutoff valve 17 and the liquid connection pipe 31, and reaches the utilization heat exchanger 23. The utilization heat exchanger 23 evaporates the refrigerant R in the gas-liquid two-phase state to provide the user with cold heat carried by the refrigerant R and generate the refrigerant R in the low-pressure gas state. Thereafter, the refrigerant R sequentially passes through the gas connection pipe 32, the gas shutoff valve 18, the four-way switching valve 12, and the accumulator 16, and then is sucked into the compressor 11 through the suction pipe 11a.

(3-2) Hot heat utilization operation

When the hot heat utilization operation is performed, the four-way switching valve 12 achieves the connection indicated by the broken line in FIG. 1 and causes the refrigerant R to proceed in the direction indicated by an arrow HO.
The compressor 11 sucks the refrigerant R in the low-pressure gas state from the suction pipe 11a, and discharges the refrigerant R in the high-pressure gas state from the discharge pipe 11b. The refrigerant R in the high-pressure gas state sequentially passes through the four-way switching valve 12, the gas shutoff valve 18, and the gas connection pipe 32, and reaches the utilization heat exchanger 23. The utilization heat exchanger 23 condenses the refrigerant R in the high-pressure gas state to provide the user with hot heat carried by the refrigerant R and generate the refrigerant R in the high-pressure liquid state. Thereafter, the refrigerant R passes through the liquid connection pipe 31 and the liquid shutoff valve 17, and reaches the heat source expansion valve 15. After that, the refrigerant R in the high-pressure liquid state is decompressed by the heat source expansion valve 15 to become the refrigerant R in the gas-liquid two-phase state. Thereafter, the refrigerant R passes through the fourth node D, the third check valve 43, and the third node C in that order. The refrigerant R then enters the heat source heat exchanger 13 at the refrigerant inlet pipe 13a. The heat source heat exchanger 13 evaporates the refrigerant R by using hot heat of air to generate the refrigerant R in the low-pressure gas state. The refrigerant R in the low-pressure gas state flows out of the heat source heat exchanger 13 through the refrigerant outlet pipe 13b and then reaches the first node A. Thereafter, the refrigerant R passes through the first check valve 41 and reaches the second node B. Thereafter, the refrigerant R sequentially passes through the four-way switching valve 12 and the accumulator 16, and then is sucked into the compressor 11 through the suction pipe 11a.

(3-3) Effects of counterflow in heat source heat exchanger 13

FIGS. 5 and 6 are examples of temperature changes of the refrigerant R and the air flow AF in the heat source heat exchanger 13. The horizontal axis represents a position y in a y direction. A position y1 is the position of the fin rear end 672, and y2 is the position of the fin front end 671. The vertical axis represents a temperature T of the refrigerant R and the air flow AF. The numerical value of the temperature T shown in the drawing is merely an example.
FIG. 5 shows temperature changes in the cold heat utilization operation. In this drawing, it is assumed that the heat source heat exchanger 13 achieves a counterflow between the refrigerant R and the air flow AF. The air flow AF proceeds from the position y1 of the fin rear end 672 to the position y2 of the fin front end 671. On the other hand, the refrigerant R proceeds from the position y2 of the fin front end 671 to the position y1 of the fin rear end 672.
The heat source heat exchanger 13 functions as a condenser. In the heat source heat exchanger 13, the refrigerant R is deprived of heat by the air flow AF. Therefore, the temperature of the refrigerant R decreases as the refrigerant R proceeds from the position y2 to the position y1. Since the air flow AF receives heat from the refrigerant R, the temperature of the air flow AF increases as the air flow AF proceeds from the position y1 to the position y2.
A temperature difference ΔT1 between the refrigerant R and the air flow AF at the position y1 and a temperature difference ΔT2 between the refrigerant R and the air flow AF at the position y2 both ensure a sufficient magnitude. Therefore, heat is transferred from the refrigerant R to the air flow AF without any trouble in an entire region of the heat source heat exchanger 13.
FIG. 6 shows temperature changes in the hot heat utilization operation. The heat source heat exchanger 13 functions as an evaporator. Since the refrigerant R receives heat from the air flow AF in the heat source heat exchanger 13, the temperature of the air flow AF decreases as the air flow AF proceeds from the position y1 to the position y2.
The refrigerant R receives heat from the air flow AF. Therefore, the temperature of the refrigerant R increases as the refrigerant R proceeds through the heat source heat exchanger 13. This drawing shows two types of temperature changes of the refrigerant R.
An arrow Rn indicates a temperature change in a comparative example. In the comparative example, it is assumed that the bridge circuit 40 does not exist in the refrigerant circuit and the refrigerant R proceeds in a direction opposite to the cold heat utilization operation. At this time, similarly to the air flow AF, the refrigerant R proceeds from the position y1 of the fin rear end 672 to the position y2 of the fin front end 671.
An arrow Rc represents a temperature change in the heat source heat exchanger 13 according to the present embodiment. The refrigerant circuit includes the bridge circuit 40, and can achieve a counterflow in the heat source heat exchanger 13 similarly to the cold heat utilization operation. At this time, the refrigerant R proceeds from the position y2 of the fin front end 671 to the position y1 of the fin rear end 672, contrary to the air flow AF.
In the comparative example indicated by the arrow Rn, a temperature difference ΔT3 between the refrigerant R and the air flow AF at the position y1 is greatly different from a temperature difference ΔT4 between the refrigerant R and the air flow AF at the position y2. A sufficient magnitude of the temperature difference ΔT4 cannot be secured. This indicates that the transfer of heat from the air flow AF to the refrigerant R can be inhibited near the fin front end 671.
On the other hand, in the present embodiment indicated by the arrow Rc, a temperature difference ΔT5 between the refrigerant R and the air flow AF at the position y1 and a temperature difference ΔT6 between the refrigerant R and the air flow AF at the position y2 both ensure a sufficient magnitude. Therefore, it is understood that the heat is transferred from the air flow AF to the refrigerant R without any trouble in the entire region of the heat source heat exchanger 13 according to the present embodiment.
When the refrigerant R having a large temperature glide such as a non-azeotropic mixed refrigerant is used, it tends to be difficult to secure a sufficient temperature difference between the refrigerant R and the air flow AF at the outlet of the refrigerant R in the heat exchanger. When a small value such as the temperature difference ΔT4 is generated, the heat exchange performance of the heat source heat exchanger 13 deteriorates. This problem can be improved by mounting the bridge circuit 40 to always achieve a counterflow between the refrigerant R and the air flow AF in the heat source heat exchanger 13.

(3-4) Circulation amount of refrigerant R

The circulation amount of the refrigerant R in the refrigeration cycle apparatus 100 varies depending on an operation situation, and increases or decreases in a range from a minimum value to a maximum value. In the refrigeration cycle apparatus 100, the circulation amount of the refrigerant R may become significantly small. In both the cold heat utilization operation and the hot heat utilization operation, the minimum value of the circulation amount of the refrigerant R in the refrigeration cycle apparatus 100 is less than 35.00 kg/h.

(4) Detailed structure of heat source heat exchanger 13

FIG. 7 shows a detailed structure of the heat source heat exchanger 13. The refrigerant path inlet 62 of the lowest path 61L is disposed at a height H1. The refrigerant path inlet 62 of the highest path 61H is disposed at a height H2. The height H0 of the plurality of exhaust ports 54 is all lower than the height H1 of the lowest path 61L.
The heat exchanger body 60 has the plurality of branch portions 64. The branch portion 64 is configured by, for example, a branched pipe having one inlet and two outlets. The branch portions 64 is provided at any of the plurality of refrigerant path inlets 62. Each branch portion 64 connects one diverger pipe 56 and two refrigerant path inlets 62.

(5) Characteristics

(5-1)
The number of the diverger pipes 56 is smaller than the number of the converger pipes 75. The number of the diverger pipes 56 is, for example, smaller than a half of the number of the converger pipes 75. Therefore, since the number of the diverger pipes 56 is small, each diverger pipe 56 can be thick in a limited space in the refrigeration cycle apparatus 100. As a result, the resistance due to the pressure loss received by the refrigerant R from the diverger pipes 56 can be reduced.
(5-2)
The height of the exhaust port 54 of the diverger body 51 of the diverger 50 is lower than the height H1 of the lowest path 61L. Accordingly, the diverger pipe 56 extending from the diverger body 51 to each refrigerant path inlet 62 is long. Even when the diverger pipe 56 is long as described above, the refrigerant R flowing through the thick diverger pipe 56 does not receive a large resistance. Therefore, the refrigerant R can flow upward in the diverger pipe 56.
(5-3)
The inner diameter of each diverger pipe 56 is 80% or more and 120% or less of the inner diameter of the heat transfer tube 65. Therefore, since the inner diameter of the diverger pipe 56 is large, the refrigerant R flowing through the diverger pipe 56 does not receive a large resistance.
(5-4)
The refrigerant R coming from the diverger pipe 56 is distributed to two refrigerant path inlets 62 at the branch portion 64. Therefore, the refrigerant R can be supplied to a large number of refrigerant paths 61 while the resistance of the diverger pipe 56 is kept small.

(6) Modifications

(6-1)
In the above embodiment, each branch portion 64 connects one diverger pipe 56 and two refrigerant path inlets 62. Alternatively, each branch portion 64 may connect one diverger pipe 56 and more than three refrigerant path inlets 62.
(6-2)
The refrigeration cycle apparatus 100 according to the above embodiment includes one heat source unit 10 and one utilization unit 20. Alternatively, the refrigeration cycle apparatus 100 according to the above embodiment may include one heat source unit 10 and a plurality of utilization units 20. The refrigeration cycle apparatus 100 may further include a plurality of heat source units 10.

(1) Overall configuration

FIG. 8 shows a configuration of a refrigeration cycle apparatus 100A according to a second embodiment. The refrigeration cycle apparatus 100A is different from the refrigeration cycle apparatus 100 according to the first embodiment in that the heat source unit 10 does not include the bridge circuit 40 and the utilization unit 20 includes a bridge circuit 80.

(2) Detailed configuration

The refrigeration cycle apparatus 100A includes a utilization heat exchanger 23 and a bridge circuit 80.

(2-1) Utilization heat exchanger 23 and utilization fan 24

Unlike the first embodiment, the utilization heat exchanger 23 and the utilization fan 24 have a similar configurations to the heat source heat exchanger 13 and the heat source fan 14 in the first embodiment. The utilization heat exchanger 23 includes a refrigerant inlet pipe 23a and a refrigerant outlet pipe 23b. The refrigerant R enters the utilization heat exchanger 23 at the refrigerant inlet pipe 23a and exits from the utilization heat exchanger 23 at the refrigerant outlet pipe 23b. The utilization fan 24 generates the air flow AF passing through the utilization heat exchanger 23 to promote heat exchange between air and the refrigerant R.

(2-2) Bridge circuit 80

The bridge circuit 80 keeps the traveling direction of the refrigerant R in the utilization heat exchanger 23 to always the same. The function of the bridge circuit 80 causes the refrigerant R to always enter the utilization heat exchanger 23 through the refrigerant inlet pipe 23a and always exit the utilization heat exchanger 23 through the refrigerant outlet pipe 23b regardless of which one of the direction indicated by the arrow CO and the direction indicated by the arrow HO the traveling direction of the refrigerant R is.
The bridge circuit 80 includes a first node A', a second node B', a third node C', and a fourth node D'. The first node A' is connected to the refrigerant outlet pipe 23b. The second node B' is connected to the compressor 11 via the four-way switching valve 12. The third node C' is connected to the refrigerant inlet pipe 23a. The fourth node D' is connected to the heat source expansion valve 15.
The bridge circuit 80 further includes a first flow path A'B' extending from the first node A' to the second node B', a second flow path B'C' extending from the second node B' to the third node C', a third flow path D'C' extending from the fourth node D' to the third node C', and a fourth flow path A'D' extending from the first node A' to the fourth node D'.
The bridge circuit 80 includes a first check valve 81, a second check valve 82, a third check valve 83, and a fourth check valve 84. These check valves keep the same traveling direction of the refrigerant R in the flow paths where it is installed and prevent backflow of the refrigerant R. The first check valve 41 is provided in the first flow path A'B' and allows the refrigerant R to flow only in a direction from the first node A' toward the second node B'. The second check valve 42 is provided in the second flow path B'C', and allows the refrigerant R to flow only in a direction from the second node B' toward the third node C'. The third check valve 43 is provided in the third flow path D'C', and allows the refrigerant R to flow only in a direction from the fourth node D' toward the third node C'. The fourth check valve 44 is provided in the fourth flow path A'D', and allows the refrigerant R to flow only in a direction from the first node A' toward the fourth node D'.

(3) Detailed structure of utilization heat exchanger 23

The utilization heat exchanger 23 according to the present embodiment has a similar configuration to the heat source heat exchanger 13 according to the first embodiment shown in FIG. 7.
The refrigerant path inlet 62 of the lowest path 61L is disposed at a height H1. The refrigerant path inlet 62 of the highest path 61H is disposed at a height H2. The height H0 of the plurality of exhaust ports 54 is all lower than the height H1 of the lowest path 61L.
The heat exchanger body 60 has the plurality of branch portions 64. The branch portion 64 is configured by, for example, a branched pipe having one inlet and two outlets. The branch portions 64 is provided at any of the plurality of refrigerant path inlets 62. Each branch portion 64 connects one diverger pipe 56 and two refrigerant path inlets 62.

(4) Characteristics

In the utilization heat exchanger 23, similarly to the heat source heat exchanger 13 according to the first embodiment, since the number of the diverger pipes 56 is smaller than the number of the converger pipes 75, each of the diverger pipes 56 can be thick. As a result, the resistance due to the pressure loss received by the refrigerant R from the diverger pipes 56 can be reduced.

(5) Modifications

The modifications of the first embodiment may be applied to the present embodiment.

(1) Overall configuration

FIG. 9 shows a configuration of a refrigeration cycle apparatus 100B according to a third embodiment. The refrigeration cycle apparatus 100B is different from the refrigeration cycle apparatus 100 according to the first embodiment and the refrigeration cycle apparatus 100A according to the second embodiment in that the heat source unit 10 and the utilization unit 20 include the bridge circuit 40 and the bridge circuit 80, respectively. The configurations of the bridge circuit 40 and the bridge circuit 80 are similar to those of the first embodiment or the second embodiment.

(2) Characteristics

Both in the heat source heat exchanger 13 and the utilization heat exchanger 23, the resistance due to the pressure loss received by the refrigerant R from the diverger pipes 56 can be reduced.

(3) Modifications

The modifications of the first or second embodiment may be applied to the present embodiment.

The embodiments of the present disclosure have been described above. It is understood that various changes to modes and details should be available without departing from the gist and the scope of the present disclosure recited in the claims.

REFERENCE SIGNS LIST

10: heat source unit
12: four-way switching valve
13: heat source heat exchanger
13a: refrigerant inlet pipe
13b: refrigerant outlet pipe
14: heat source fan
20: utilization unit
23: utilization heat exchanger
23a: refrigerant inlet pipe
23b: refrigerant outlet pipe
24: utilization fan
30: connection pipe group
40, 80: bridge circuit (refrigerant rectifier)
50: diverger
51: diverger body
53: intake port
54: exhaust port
56: diverger pipe
60: heat exchanger body
61: refrigerant path
61H: highest path
61L: lowest path
62: refrigerant path inlet
63: refrigerant path outlet
64: branch portion
65: heat transfer tube
70: converger
75: converger pipe
76: converger body
100, 100A, 100B: refrigeration cycle apparatus
H0: height of exhaust port
H1: height of lowest path
H2: height of highest path
R: refrigerant

CITATION LIST

PATENT LITERATURE

Patent Literature 1: JP 2009-222362 A

Claims

A refrigeration cycle apparatus (100) comprising:
a four-way switching valve (12) that switches between a first operation and a second operation;

a first heat exchanger (13) that includes a refrigerant inlet pipe (13a) and a refrigerant outlet pipe (13b), functions as a condenser in the first operation, and functions as an evaporator in the second operation;

a second heat exchanger (23) that functions as an evaporator in the first operation and functions as a condenser in the second operation; and

a refrigerant rectifier (40) that causes a refrigerant to flow into the first heat exchanger at the refrigerant inlet pipe and flow out of the first heat exchanger at the refrigerant outlet pipe in both the first operation and the second operation,

wherein the first heat exchanger includes
a heat exchanger body (60) including a plurality of refrigerant paths (61) through which the refrigerant passes,

a diverger (50) that diverges the refrigerant into the plurality of refrigerant paths, and

a converger (70) that converges the refrigerant from the plurality of refrigerant paths,

the diverger includes
a diverger body (51) including one intake port (53) and a plurality of exhaust ports (54), the intake port being connected to the refrigerant inlet pipe, and

a plurality of diverger pipes (56) respectively connecting the plurality of exhaust ports and the plurality of refrigerant paths,

the converger includes
a plurality of converger pipes (75) connected to the plurality of refrigerant paths, and

a converger body (76) connected to all the plurality of converger pipes and the refrigerant outlet pipe, and

a number of the plurality of diverger pipes (56) is smaller than a number of the plurality of converger pipes (75).
The refrigeration cycle apparatus according to claim 1, wherein
the plurality of refrigerant paths includes
a lowest path (61L) disposed at a height (H1) that is lowest; and

a highest path (61H) disposed at a height (H2) that is highest, and

a height (H0) of the plurality of exhaust ports is all lower than the height (H1) of the lowest path.
The refrigeration cycle apparatus according to claim 1 or 2, wherein the number of the plurality of diverger pipes (56) is smaller than a half of the number of the plurality of converger pipes (75).
The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein
each of the plurality of refrigerant paths includes a heat transfer tube (65), and

an inner diameter of all of the plurality of diverger pipes is 80% or more and 120% or less of an inner diameter of the heat transfer tube.
The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein
the heat exchanger body includes
a plurality of refrigerant path inlets (62) that is a portion through which the refrigerant flows into the plurality of refrigerant paths, and

a plurality of branch portions (64) provided at any of the plurality of refrigerant path inlets, and

each of the plurality of branch portions (64) connects one of the plurality of diverger pipes (56) and at least two of the plurality of refrigerant path inlets (62).