CN117355721A

CN117355721A - Heat exchanger, outdoor unit of air conditioner provided with heat exchanger, and air conditioner provided with outdoor unit of air conditioner

Info

Publication number: CN117355721A
Application number: CN202180098566.0A
Authority: CN
Inventors: 尾中洋次; 七种哲二; 足立理人; 岸田七海; 五明泰作; 中尾祐基; 笠木伸吾; 岐部笃史; 森本裕之
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2021-05-28
Filing date: 2021-05-28
Publication date: 2024-01-05
Also published as: JPWO2022249425A1; WO2022249425A1; EP4350252A1; US20240219067A1

Abstract

The heat exchanger is mounted on an outdoor unit of an air conditioner, and comprises a heat exchanger core having a plurality of flat tubes extending in a vertical direction, or more than two heat exchanger cores along a flow direction of air, wherein a hot gas refrigerant inlet through which a refrigerant flows is formed in a lower portion of the heat exchanger when the heat exchanger functions as a condenser, and a flow path cross-sectional area of each flat tube is defined as a [ m ] ² ]The number of flat tubes is N]The total flow path cross-sectional area of the heat exchanger core is defined as Am ² ]＝a×N[m ² ]The height of the heat exchanger core is defined as Hm]The differential pressure of the refrigerant flow path is defined as Δp _HEX The liquid head is defined as ΔP _HEAD In the case of (1), satisfy ΔP _HEX /ΔP _HEAD ＝(5.94635×10 ^－4 ×A ^－1.75030 )/(8.4303H+0.8779)＞1。

Description

Heat exchanger, outdoor unit of air conditioner provided with heat exchanger, and air conditioner provided with outdoor unit of air conditioner

Technical Field

The present disclosure relates to a heat exchanger having a plurality of flat tubes, an outdoor unit of an air conditioner having the heat exchanger, and an air conditioner having the outdoor unit of the air conditioner.

Background

Conventionally, there is a heat exchanger (for example, refer to patent document 1) provided with: a plurality of flat tubes arranged at intervals in the horizontal direction, the flat tubes being in the tube extending direction in the vertical direction; a plurality of fins connected throughout the space between adjacent flat tubes, for conducting heat to the flat tubes; and headers provided at upper and lower ends of the plurality of flat tubes, respectively.

The heat exchanger of patent document 1 is mounted in an outdoor unit of an air conditioner capable of both cooling operation and heating operation. When the heating operation is performed in a low-temperature environment in which the outside air temperature is low and the surface temperature of the heat exchanger is 0 ℃ or lower, frost is generated in the heat exchanger. Therefore, when the amount of frost formed on the heat exchanger becomes equal to or greater than a predetermined amount, defrosting operation is performed to melt the frost on the surface of the heat exchanger. In the defrosting operation, the high-temperature and high-pressure gas refrigerant is caused to flow from one header and into the flat tubes to defrost the evaporator.

Patent document 1: japanese patent application laid-open No. 2018-96638

In the conventional heat exchanger as described in patent document 1, during defrosting operation, the high-temperature and high-pressure gas refrigerant flows in from the header at the lower part and flows as an upward flow in the flat tubes, and the liquid phase increases as it flows down the flat tubes while being cooled. Further, the following problems exist: when a high-temperature and high-pressure gas refrigerant flows through the flat tubes as an upward flow, liquid retention occurs in which the liquefied refrigerant cannot rise and remain under the influence of gravity, and defrosting performance is reduced.

Disclosure of Invention

The present disclosure has been made to solve the above-described problems, and an object of the present disclosure is to provide a heat exchanger capable of suppressing a decrease in defrosting performance, an outdoor unit of an air conditioner provided with the heat exchanger, and an air conditioner provided with the outdoor unit of the air conditioner.

The heat exchanger according to the present disclosure is mounted in an outdoor unit of an air conditioner, the heat exchanger includes one heat exchanger core or two or more heat exchanger cores along a flow direction of air, the heat exchanger core includes a plurality of flat tubes extending in a vertical direction, when the heat exchanger functions as a condenser, a refrigerant flows as an upward flow in the flat tubes, and a flow path cross-sectional area of each flat tube is defined as a [ m ] ² ]The number of the flat tubes is N]The total flow path cross-sectional area of the heat exchanger core is defined as Am ² ]＝a×N[m ² ]The height of the heat exchanger core is defined as Hm]The differential pressure of the refrigerant flow path is defined as Δp _HEX The liquid head is defined as ΔP _HEAD In the case of (1), satisfy ΔP _HEX /ΔP _HEAD ＝(5.94635×10 ^－4 ×A ^－1.75030 )/(8.4303H+0.8779)＞1。

The outdoor unit of the air conditioner according to the present disclosure includes the heat exchanger described above.

The air conditioner according to the present disclosure includes: an outdoor unit of the air conditioner; an indoor unit of an air conditioner; and a refrigerant circuit for circulating a refrigerant, the refrigerant circuit being composed of an outdoor unit of the air conditioner and an indoor unit of the air conditioner.

According to the heat exchanger, the outdoor unit of the air conditioner provided with the heat exchanger, and the air conditioner provided with the outdoor unit of the air conditioner, the heat exchanger satisfies Δp _HEX /ΔP _HEA ＝(5.94635×10 ^－4 ×A ^－1.75030 ) /(8.4303H+0.8779) > 1. Therefore, when the heat exchanger functions as a condenser, the occurrence of liquid retention in which the liquefied refrigerant cannot rise and remain due to the influence of gravity can be suppressed when the refrigerant flows as an upward flow in the flat tubes, and a decrease in defrosting performance can be suppressed.

Drawings

Fig. 1 is a refrigerant circuit diagram of an air conditioner provided with a heat exchanger according to embodiment 1.

Fig. 2 is a perspective view of the heat exchanger according to embodiment 1.

Fig. 3 is a front view of the heat exchanger according to embodiment 1.

Fig. 4 is a view showing the flow path cross-sectional area of the flat tube of the heat exchanger according to embodiment 1.

FIG. 5 is a graph showing the total flow path cross-sectional area and ΔP of the heat exchanger core of the heat exchanger based on the experimental results _HEX /ΔP _HEAD Is a graph of the relationship of (1).

FIG. 6 is a graph showing the heights H and ΔP of the heat exchanger core of the heat exchanger based on the experimental results _HEX /ΔP _HEAD Is a graph of the relationship of (1).

Fig. 7 is a diagram illustrating a decrease in defrosting performance caused by liquid retention in the heat exchanger.

Fig. 8 is a diagram illustrating the heating capacity of the heat exchanger according to embodiment 1 with time.

Fig. 9 is a diagram illustrating the heating capacity of a conventional heat exchanger with time.

FIG. 10 shows the basis of an experimentH/L and liquid head ΔP of resulting heat exchanger _HEAD Is a graph of the relationship of (1).

Fig. 11 is a diagram showing the pressure distribution inside the heat exchanger according to embodiment 1.

Fig. 12 is a diagram showing the internal pressure distribution of a modification of the heat exchanger according to embodiment 1.

Fig. 13 is a schematic view showing the periphery of a header flow path of the heat exchanger according to embodiment 1.

Fig. 14 is a graph illustrating heat exchanger performance of the heat exchanger according to embodiment 2.

Fig. 15 is a diagram illustrating heat exchanger performance of a modification of the heat exchanger according to embodiment 2.

Fig. 16 is a perspective view schematically showing a heat exchanger according to embodiment 3.

Fig. 17 is an enlarged view of the periphery of the cross-row header of the heat exchanger according to embodiment 3.

FIG. 18 shows the gap delta and differential pressure delta P of the heat exchanger based on the experimental results _2－3 Is a graph of the relationship of (1).

Fig. 19 is a schematic side view of a heat exchanger according to embodiment 3.

Fig. 20 is an enlarged refrigerant circuit diagram of an outdoor unit of an air conditioner according to embodiment 4.

Fig. 21 is an enlarged refrigerant circuit diagram of an outdoor unit of an air conditioner according to embodiment 5.

Fig. 22 is a schematic cross-sectional view of a flat tube of the heat exchanger according to embodiment 6.

Fig. 23 is a schematic cross-sectional view of a flat tube of a modification of the heat exchanger according to embodiment 6.

Fig. 24 is a schematic side view of a flat tube of a modification of the heat exchanger according to embodiment 6.

Fig. 25 shows the type and Δp of the refrigerant used in the refrigerant circuit of the air conditioner according to embodiment 7 _HEX /ΔP _HEAD Is a graph of the relationship of (1).

Fig. 26 is a front view of a heat exchanger of an air conditioner according to embodiment 8.

Fig. 27 is a front view of a heat exchanger of an air conditioner according to embodiment 9.

Detailed Description

Embodiments of the present disclosure will be described below based on the drawings. Further, the present disclosure is not limited to the embodiments described below. In the following drawings, the relationship between the sizes of the constituent members may be different from the actual ones.

Embodiment 1

Structure of air conditioner 100

Fig. 1 is a refrigerant circuit diagram of an air conditioner 100 including a heat exchanger 30 according to embodiment 1. The solid arrows in fig. 1 indicate the flow of the refrigerant during the cooling operation, and the broken arrows in fig. 1 indicate the flow of the refrigerant during the heating operation.

As shown in fig. 1, the heat exchanger 30 according to embodiment 1 is mounted on an outdoor unit 10 of an air conditioner 100 including the outdoor unit 10 and the indoor unit 20. The outdoor unit 10 includes a compressor 11, a flow path switching device 12, and a fan 13 in addition to the heat exchanger 30. The indoor unit 20 includes a throttle device 21, an indoor heat exchanger 22, and an indoor fan 23.

The air conditioner 100 further includes a refrigerant circuit 101, and the refrigerant circuit 101 is configured by the outdoor unit 10 and the indoor unit 20, and is configured to circulate a refrigerant. Specifically, the refrigerant circuit 101 is configured by connecting the compressor 11, the flow path switching device 12, the heat exchanger 30, the expansion device 21, and the indoor heat exchanger 22 with refrigerant pipes. The air conditioner 100 can perform both cooling operation and heating operation by switching the flow path switching device 12.

The compressor 11 sucks a low-temperature low-pressure refrigerant, compresses the sucked refrigerant, and discharges a high-temperature high-pressure refrigerant. The compressor 11 is configured by, for example, a variable frequency compressor or the like that controls the capacity, which is the amount of output per unit time, by varying the operating frequency.

The flow path switching device 12 is, for example, a four-way valve, and switches between a cooling operation and a heating operation by switching the direction of the flow of the refrigerant. The flow path switching device 12 is switched to a state shown by a solid line in fig. 1 during the cooling operation, and connects the discharge side of the compressor 11 and the heat exchanger 30. The flow path switching device 12 is switched to a state shown by a broken line in fig. 1 during the heating operation, and connects the discharge side of the compressor 11 and the indoor heat exchanger 22.

The heat exchanger 30 exchanges heat between the outdoor air and the refrigerant. The heat exchanger 30 functions as a condenser that radiates heat of the refrigerant to outdoor air and condenses the refrigerant during the cooling operation. The heat exchanger 30 functions as an evaporator that evaporates the refrigerant and cools the outdoor air by the heat of vaporization at that time during the heating operation.

The fan 13 supplies outdoor air to the heat exchanger 30, and adjusts the air supply amount to the heat exchanger 30 by controlling the rotation speed.

The expansion device 21 is, for example, an electronic expansion valve capable of adjusting the opening degree of the expansion, and controls the pressure of the refrigerant flowing into the heat exchanger 30 or the indoor heat exchanger 22 by adjusting the opening degree. In embodiment 1, the throttle device 21 is provided in the indoor unit 20, but may be provided in the outdoor unit 10, and the location is not limited.

The indoor heat exchanger 22 exchanges heat between indoor air and refrigerant. The indoor heat exchanger 22 functions as an evaporator that evaporates the refrigerant and cools the outdoor air by the heat of vaporization at that time during the cooling operation. The indoor heat exchanger 22 functions as a condenser that radiates heat of the refrigerant to the outdoor air and condenses the refrigerant during the heating operation.

The indoor fan 23 supplies indoor air to the indoor heat exchanger 22, and adjusts the amount of air supplied to the indoor heat exchanger 22 by controlling the rotational speed.

Structure of heat exchanger 30

Fig. 2 is a perspective view of a heat exchanger 30 according to embodiment 1. Fig. 3 is a front view of a heat exchanger 30 according to embodiment 1. The broken line arrows in fig. 2 and the white arrows in fig. 3 indicate the flow of the refrigerant during the cooling operation. Fig. 3 shows a height H and a width L of a heat exchanger core 31 described later.

As shown in fig. 2, the heat exchanger 30 includes a heat exchanger core 31, and the heat exchanger core 31 includes a plurality of flat tubes 38 and a plurality of fins 39. The flat tubes 38 are arranged in parallel in the horizontal direction (the left-right direction in fig. 2) with a gap therebetween so that wind generated by the fan 13 flows, and the refrigerant flows in the vertical direction in the tubes extending in the vertical direction (the up-down direction in fig. 2). The fins 39 are connected between adjacent flat tubes 38, and conduct heat to the flat tubes 38. The fins 39 improve the heat exchange efficiency between the air and the refrigerant, and for example, corrugated fins are used. However, the present invention is not limited thereto. Since heat exchange between the air and the refrigerant is performed on the surfaces of the flat tubes 38, the fins 39 may be omitted.

A 1 st header 34 is provided at the lower end portion of the heat exchanger core 31. The 1 st header 34 has the lower end portions of the flat tubes 38 of the heat exchanger core 31 directly inserted therein. Further, a 2 nd header 35 is provided at the upper end portion of the heat exchanger core 31. The header 35 is directly inserted into the upper end portion of the flat tube 38 of the heat exchanger core 31.

A hot gas refrigerant inlet 32 is formed at one end of the 1 st header 34, and the hot gas refrigerant inlet 32 is connected to the refrigerant circuit 101 of the air conditioner 100 via a gas pipe 37. Thus, header 1 34 is also referred to as a gas header. The 1 st header 34 flows high-temperature and high-pressure gas refrigerant (hereinafter also referred to as hot gas refrigerant) from the compressor 11 into the heat exchanger 30 during cooling operation, and flows low-temperature and low-pressure gas refrigerant after heat exchange in the heat exchanger 30 out of the refrigerant circuit 101 during heating operation. That is, the hot gas refrigerant inlet 32 serves as a hot gas refrigerant inflow portion. Here, the hot gas refrigerant is not limited to a gas single-phase refrigerant, and may be a gas-liquid two-phase refrigerant including a gas phase at 0 ℃ or higher.

A liquid refrigerant outlet 33 is formed at one end of the 2 nd header 35, and the liquid refrigerant outlet 33 is connected to the refrigerant circuit 101 of the air conditioner 100 via a liquid pipe 36. Thus, header 2 35 is also referred to as a liquid header. The 2 nd header 35 flows low-temperature low-pressure two-phase refrigerant into the heat exchanger 30 during the heating operation, and flows low-temperature high-pressure liquid refrigerant after heat exchange in the heat exchanger 30 out of the refrigerant circuit 101 during the cooling operation.

The plurality of flat tubes 38, the plurality of fins 39, the 1 st header 34, and the 2 nd header 35 are all made of aluminum, and are joined by brazing.

Next, operations at the time of each operation of the air conditioner 100 will be described with reference to fig. 1 and 2.

< refrigeration operation >)

The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the heat exchanger 30 through the flow switching device 12. The high-temperature and high-pressure gas refrigerant flowing into the heat exchanger 30 condenses while exchanging heat with the outdoor air introduced by the fan 13 to dissipate heat, becomes a low-temperature and high-pressure liquid refrigerant, and flows out of the heat exchanger 30. The low-temperature high-pressure liquid refrigerant flowing out of the heat exchanger 30 is depressurized by the throttle device 21, becomes a low-temperature low-pressure gas-liquid two-phase refrigerant, and flows into the indoor heat exchanger 22. The low-temperature low-pressure gas-liquid two-phase refrigerant flowing into the indoor heat exchanger 22 evaporates while exchanging heat with the indoor air introduced by the indoor fan 23 to absorb heat, cools the indoor air, and then becomes a low-temperature low-pressure gas refrigerant and flows out of the indoor heat exchanger 22. The low-temperature and low-pressure gas refrigerant flowing out of the indoor heat exchanger 22 is sucked into the compressor 11, and is again high-temperature and high-pressure gas refrigerant.

< heating operation >)

The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchanger 22 through the flow switching device 12. The high-temperature and high-pressure gas refrigerant flowing into the indoor heat exchanger 22 condenses while exchanging heat with and dissipating heat from the indoor air introduced by the indoor fan 23, heats the indoor air, turns into a low-temperature and high-pressure liquid refrigerant, and flows out of the indoor heat exchanger 22. The low-temperature high-pressure liquid refrigerant flowing out of the indoor heat exchanger 22 is depressurized by the throttle device 21, becomes a low-temperature low-pressure gas-liquid two-phase refrigerant, and flows into the heat exchanger 30. The low-temperature low-pressure gas-liquid two-phase refrigerant flowing into the heat exchanger 30 absorbs heat by heat exchange with the outdoor air introduced by the fan 13 and evaporates, thereby becoming a low-temperature low-pressure gas refrigerant and flowing out of the heat exchanger 30. The low-temperature and low-pressure gas refrigerant flowing out of the heat exchanger 30 is sucked into the compressor 11, and is again high-temperature and high-pressure gas refrigerant.

< defrosting operation >)

When the heating operation is performed in a low-temperature environment in which the surface temperatures of the flat tubes 38 and the fins 39 shown in fig. 2 are 0 ℃ or lower, frost is generated in the heat exchanger 30. When the amount of frost formed on the heat exchanger 30 becomes equal to or greater than a predetermined amount, the air passage of the heat exchanger 30 through which the air generated by the fan 13 passes is blocked, and the performance of the heat exchanger 30 is reduced, and the heating performance is reduced. Therefore, when the heating performance is lowered, the defrosting operation is performed to melt the frost on the surface of the heat exchanger 30.

In the defrosting operation, the fan 13 is stopped, and the flow path switching device 12 is switched to the same state as in the cooling operation, so that the high-temperature and high-pressure gas refrigerant flows into the heat exchanger 30. Thereby, frost adhering to the flat tubes 38 and the fins 39 melts. When the defrosting operation is started, the high-temperature and high-pressure gas refrigerant flows from the gas piping 37 through the 1 st header 34 to each flat tube 38. The refrigerant flowing into each flat tube 38 is an upward flow flowing upward in the vertical direction. The frost adhering to the flat tubes 38 and the fins 39 is melted by the high-temperature refrigerant flowing into the flat tubes 38, and turns into water. The water generated by the melting of the frost is discharged downward of the heat exchanger 30 along the flat tubes 38 or the fins 39. When the adhered frost is melted, the defrosting operation is ended, and the heating operation is restarted. The timing at which the defrosting operation is ended and the heating operation is restarted may be determined by a known method. For example, the structure may be as follows: when the detected temperature of the temperature sensor, not shown, becomes a predetermined temperature, or when the defrosting operation is performed for a certain period of time, the defrosting operation is ended and the heating operation is restarted.

Fig. 4 is a view showing the flow path cross-sectional area of the flat tube 38 of the heat exchanger 30 according to embodiment 1. FIG. 5 is a heat exchanger core showing a heat exchanger based on experimental results31 total flow path cross-sectional area ΔP _HEX /ΔP _HEAD Is a graph of the relationship of (1). FIG. 6 shows the heights H and ΔP of the heat exchanger core 31 of the heat exchanger based on the experimental results _HEX /ΔP _HEAD Is a graph of the relationship of (1). Fig. 7 is a diagram illustrating a decrease in defrosting performance caused by liquid retention in the heat exchanger. The white arrows in fig. 7 indicate the flow of the refrigerant during the defrosting operation.

When the total flow path cross-sectional area of the heat exchanger core 31 is defined as a, the total flow path cross-sectional area a is obtained by the following equation (1).

A＝a×N[m ² ]·····(1)

a: flow cross-sectional area [ m ] of each flat tube 38 ² ](diagonal line portion of FIG. 4)

N: number of flat tubes 38 [ root ]

In addition, a differential pressure of the refrigerant flow path (hereinafter referred to as a flow path differential pressure) is defined as Δp _HEX The liquid head is defined as ΔP _HEAD In the case of DeltaP _HEX /ΔP _HEAD The result is obtained by the following equation (2). In embodiment 1, the flow path differential pressure Δp _HEX The differential pressure of the flow path through which the hot gas refrigerant flows as an upward flow during the defrosting operation is the differential pressure of the upper and lower ends of the flat tubes 38 in the heat exchanger core 31.

ΔP _HEX /ΔP _HEAD ＝(5.94635×10 ^－4 ×A ^－1.75030 )/(8.4303H×0.8779)·····(2)

A: total flow path cross-sectional area [ m ] of heat exchanger core 31 ² ]

H: height of heat exchanger core 31 [ m ]

Here, the height H of the heat exchanger core 31 is a length between the upper end of the 1 st header 34 and the lower end of the 2 nd header 35, and is a length of the exposed portion of the flat tube 38.

The above formula (2) is an experimental formula obtained from the numerical analysis of the inventors and the experimental result, and uses the flow path differential pressure Δp _HEX The shape parameter of the dominant heat exchanger 30, i.e. the total flow path cross-sectional area A [ m ] of the heat exchanger core 31 ² ]And a liquid head ΔP _HEAD The shape parameter of the predominant heat exchanger 30, i.e. the height Hm of the heat exchanger core 31]The heat exchanger 30 is formulated in a range of conditions for the outdoor unit 10 used for buildings, shops, homes, and the like (hereinafter, referred to as a building or the like). This experimental formula is shown in fig. 5 and 6. Fig. 5 is a diagram of fixing the height H of the heat exchanger core 31 and varying the total flow path cross-sectional area a of the heat exchanger core 31, and fig. 6 is a diagram of fixing the total flow path cross-sectional area a of the heat exchanger core 31 and varying the height H of the heat exchanger core 31.

According to the experiments of the inventors, as shown in FIG. 5, the total flow path cross-sectional area A [ m ] of the heat exchanger core 31 ² ]Become larger, ΔP _HEX /ΔP _HEAD With a tendency to decrease. In addition, as shown in FIG. 6, the height Hm of the heat exchanger core 31 is increased]Becomes higher, deltaP _HEX /ΔP _HEAD With a tendency to decrease. Further, as shown in fig. 5 and 6, it is found from the experimental results that Δp is as follows _HEX /ΔP _HEAD When the hot gas refrigerant flowing into the 1 st header 34 flows as an upward flow in the flat tubes 38 of the heat exchanger core 31, liquid retention occurs in a part of the hot gas flow region, in which the refrigerant liquefied by the influence of gravity cannot rise and remains, which leads to a significant decrease in defrosting performance. In addition, as shown in fig. 7, when liquid stagnation occurs, even if defrosting operation is performed in a region where the liquid stagnation occurs (hereinafter, referred to as a liquid stagnation region), a frost remaining region where frost adhering to the flat tube 38 and the fin 39 remains without melting is generated.

In general, in an air conditioner for an automobile or the like, engine heat is used at the time of heating, and a heat pump is used only at the time of cooling. Therefore, a heat exchanger using corrugated fins for an outdoor unit of an automobile air conditioner or the like is often used for a heat exchanger dedicated for cooling, and therefore is used for a purpose where defrosting operation is not generated. In addition, even when the heat exchanger is used as a heat pump in both cooling and heating, the heat exchanger core has a height of about 300 mm and is often small, whereas in a heat exchanger used in an outdoor unit of a building or the like, the heat exchanger core has a height of 420 mm or more and also has a height of 800 mm or more.

As a result of the study by the inventors, it has been found that, in the case where a heat exchanger used in an outdoor unit of an automobile air conditioner or the like is to be applied to an outdoor unit of a building or the like, for example, if the height H of the heat exchanger core 31 is made to be 420[ mm ] high]About, as shown in FIG. 6, about 300[ mm ]]Is a high heat exchanger core, Δp _HEX /ΔP _HEAD Reduce by 43[%]. As is clear from this, liquid retention occurs in a part of the heat exchanger, which is difficult for the liquid refrigerant to flow. Further, as a result of the study by the inventors, it was found that the height H of the heat exchanger core 31 was 490[ mm ]]In the case of (C) relative to 300[ mm ]]Is a high heat exchanger core, Δp _HEX /ΔP _HEAD About 50[%]At a height H of the heat exchanger core 31 of 800[ mm ]]In the case of (C) relative to 300[ mm ]]Is a high heat exchanger core, Δp _HEX /ΔP _HEAD About 65[%]。

Further, at ΔP _HEX /ΔP _HEAD Under the condition of less than 1, deltaP _HEX /ΔP _HEAD The smaller the liquid retention area, the larger. Therefore, the height H relative to the heat exchanger core 31 is 300[ mm ]]In case of DeltaP _HEX /ΔP _HEAD Reduce by 43[%]～65[％]This condition suggests that it has a great impact on heat exchanger performance. As a result of experiments by the inventors, as an example, when ΔP _HEX /ΔP _HEAD When 1 or less, the height H relative to the heat exchanger core 31 is 300[ mm ] ]In (2) the heat exchanger performance is reduced by 30[%]～50[％]Left and right.

Conventionally, there are problems that: when the height H of the heat exchanger core 31 is 420[ mm ] or more, when the hot gas refrigerant flows into the 1 st header 34 provided at the lower portion of the heat exchanger and flows as an upward flow through the 1 st header 34 inside the flat tubes 38 extending in the vertical direction, liquid retention occurs in which the refrigerant liquefied by the influence of gravity cannot rise and remains, and defrosting performance in this region is significantly reduced. Therefore, in embodiment 1, this is improved to suppress a decrease in defrosting performance during defrosting operation.

As can be seen from the experimental results, as shown in FIG. 5 and FIG. 6, if ΔP _HEX /ΔP _HEAD If the ratio is more than 1, the generation of liquid retention can be suppressed. Therefore, in embodiment 1, in order to suppress the occurrence of liquid stagnation to suppress the decrease in defrosting performance at the time of defrosting operation, Δp is satisfied _HEX /ΔP _HEAD The heat exchanger 30 is configured in a manner of > 1.

Fig. 8 is a diagram illustrating the heating capacity of the heat exchanger 30 according to embodiment 1 with time. Fig. 9 is a diagram illustrating the heating capacity of a conventional heat exchanger with time.

As before, the method does not meet the delta P _HEX /ΔP _HEAD When the heat exchanger is configured in the system of > 1, liquid retention occurs during the defrosting operation, and frost is not sufficiently removed in the liquid retention region where the liquid retention occurs, and the frost remains. Therefore, as shown in fig. 9, the heating capacity in the heating operation gradually decreases with the passage of time.

On the other hand, as in embodiment 1, the following is performed to satisfy Δp _HEX /ΔP _HEAD When the heat exchanger 30 is configured in the manner of > 1, the occurrence of liquid stagnation is suppressed during the defrosting operation, and the frost remaining can be suppressed. Therefore, as shown in fig. 8, even when a period of time has elapsed, it is possible to suppress a decrease in heating capacity during heating operation, and it is possible to improve heating capacity during heating operation.

In addition, as shown in FIG. 3, when the width of the heat exchanger core 31 is defined as L [ m ], the heat exchanger 30 is configured so as to satisfy H/L > 1. Here, the width L of the heat exchanger core 31 is a distance between outer side portions of the flat tubes 38 disposed on both outermost sides among the plurality of flat tubes 38 disposed in the horizontal direction.

FIG. 10 is a graph showing H/L and ΔP of a heat exchanger based on experimental results _HEAD Is a graph of the relationship of (1). In addition, FIG. 10 shows the H/L and the liquid head ΔP in the case of working fluid flow to the heat exchanger _HEAD Is a relationship of (3).

In the heat exchanger, when the height of the heat exchanger coreH is high, and when the aspect ratio (aspect ratio) of the heat exchanger becomes large in the height direction, i.e., H/L becomes large, the liquid head ΔP is as shown in FIG. 10 _HEAD And becomes larger. Also, when the liquid head ΔP _HEAD When becoming larger, ΔP _HEX /ΔP _HEAD And becomes smaller, thereby causing liquid to stagnate, resulting in a significant decrease in defrosting performance. However, as long as ΔP is satisfied _HEX /ΔP _HEAD The heat exchanger of > 1, which is used for outdoor units of buildings with H/L > 1, can inhibit liquid retention.

Fig. 11 is a diagram illustrating the pressure distribution inside the heat exchanger 30 according to embodiment 1. Fig. 12 is a diagram illustrating the internal pressure distribution of a modification of the heat exchanger 30 according to embodiment 1. The white arrows and the black arrows in fig. 11 and 12 indicate the flow of the refrigerant during the defrosting operation.

In embodiment 1, as shown in fig. 11, the hot gas refrigerant inlet 32 and the liquid refrigerant outlet 33 are provided at the end portions on the same side as the 1 st header 34 and the 2 nd header 35, respectively. In contrast, in the modification of embodiment 1, the hot gas refrigerant inlet 32 and the liquid refrigerant outlet 33 are provided at the opposite ends of the 1 st header 34 and the 2 nd header 35, respectively.

As shown in fig. 11, in the case where the hot gas refrigerant inlet 32 and the liquid refrigerant outlet 33 are provided at the end portions on the same side as the 1 st header 34 and the 2 nd header 35, respectively, the refrigerant flow rates flowing through the positions (1) → (4) in fig. 11 are defined as G _1－4 The refrigerant flow rate flowing through the position (2) →the position (3) of fig. 11 is defined as G _2－3 G is then _1－4 ＞G _2－3 . This is because of the pressure loss Δp received by the 1 st header 34 _1－2 Pressure loss Δp with header 2 35 _3－4 The effect of the difference, ΔP, in FIG. 10 at the differential pressure between position (1) and position (4) _1－4 Differential pressure Δp between position (2) and position (3) of fig. 11 _2－3 Relatively large. In other words, the flow path differential pressure Δp becomes greater as the hot gas refrigerant inlet 32 and the liquid refrigerant outlet 33 are separated from each other _HEX And becomes smaller. Thus, remote from the hot gas refrigerant inlet 32 and from the liquidThe position of the refrigerant outlet 33 is likely to generate a flow path differential pressure Δp _HEX A region of reduced Δp _HEX /ΔP _HEAD And thus liquid retention is liable to occur.

On the other hand, as shown in fig. 12, when the hot gas refrigerant inlet 32 and the liquid refrigerant outlet 33 are provided at the ends of positions which are opposite sides of the 1 st header 34 and the 2 nd header 35, respectively, the pressure loss Δp of the 1 st header 34 _1－2 Pressure loss Δp with header 2 35 _3－4 The difference becomes smaller. Therefore, these effects are reduced, and the refrigerant flow rate G flowing through the position (1) →the position (4) in fig. 12 _1－4 And the refrigerant flow rate G flowing through the position (2) to the position (3) of FIG. 12 _2－3 The difference becomes smaller. Therefore, the flow path differential pressure Δp is less likely to occur _HEX The smaller area is thereby suppressed in the occurrence of liquid retention, and thus frost remaining can be suppressed.

Fig. 13 is a schematic view showing the periphery of the header flow path of the heat exchanger 30 according to embodiment 1. Although the header flow path periphery of the 1 st header 34 is shown in fig. 13, the same applies to the header flow path periphery of the 2 nd header 35.

As described above, by configuring the heat exchanger 30 so as to satisfy H/L > 1, the lengths of the 1 st header 34 and the 2 nd header 35 can be reduced with respect to the heat exchange amount, and therefore, the pressure loss of the working fluid flowing inside the 1 st header 34 and the 2 nd header 35 can be suppressed. That is, the pressure loss Δp of the 1 st header 34 described in fig. 11 and 12 can be reduced _1－2 Pressure loss Δp with header 2 35 _3－4 The difference can be correspondingly increased by delta P _2－3 Therefore, the occurrence of liquid retention can be suppressed. In particular, in the heat exchanger 30 using the flat tubes 38, since the 1 st header 34 and the 2 nd header 35 are joined to the flat tubes 38 by brazing, the flat tubes 38 are inserted into header flow paths formed in the 1 st header 34 and the 2 nd header 35 as shown in fig. 13. In this case, in addition to the friction loss of the general header flow path, the phenomenon of enlargement and reduction of the working fluid protruding to the ends of the flat tubes 38 of the header flow path occurs, which is caused by This greatly increases the pressure loss. Experiments by the inventors have shown that there are cases where the pressure loss due to the reduction or enlargement of the working fluid is about 50% or more with respect to the frictional fluid resistance, and this effect becomes remarkable as the number of inserted flat tubes 38 increases. In this case, by configuring the heat exchanger 30 so as to satisfy H/L > 1, the pressure loss in the 1 st header 34 and the 2 nd header 35 can be suppressed.

As described above, the heat exchanger 30 according to embodiment 1 is the heat exchanger 30 mounted on the outdoor unit 10 of the air conditioner 100, and the heat exchanger 30 includes one heat exchanger core 31, or two or more heat exchanger cores 31 are provided along the air flow direction, and the heat exchanger core 31 includes the plurality of flat tubes 38 extending in the up-down direction, and when the heat exchanger 30 functions as a condenser, the refrigerant flows as an upward flow inside the flat tubes 38. In addition, the flow path cross-sectional area of each flat tube 38 is defined as a [ m ] ² ]The number of flat tubes 38 is N]The total flow path cross-sectional area of the heat exchanger core 31 at this time is defined as Am ² ]＝a×N[m ² ]The height of the heat exchanger core 31 is defined as Hm]The differential pressure of the refrigerant flow path is defined as Δp _HEX The liquid head is defined as ΔP _HEAD In the case of (1), satisfy ΔP _HEX /ΔP _HEAD ＝(5.94635×10 ^－4 ×A ^－1.75030 )/(8.4303H+0.8779)＞1。

According to the heat exchanger 30 according to embodiment 1, the heat exchanger 30 satisfies Δp _HEX /ΔP _HEA ＝(5.94635×10 ^－4 ×A ^－1.75030 ) /(8.4303H+0.8779) > 1. Therefore, when the heat exchanger 30 functions as a condenser, the refrigerant flows as an upward flow in the flat tubes 38, and thus, the occurrence of liquid retention in which the liquefied refrigerant cannot rise and remains due to the influence of gravity can be suppressed, and the decrease in defrosting performance can be suppressed.

In the heat exchanger 30 according to embodiment 1, H/L > 1 is satisfied when the width of the heat exchanger core 31 is defined as lm.

According to the heat exchanger 30 of embodiment 1, H/L > 1 is satisfied. Therefore, the lengths of the 1 st header 34 and the 2 nd header 35 can be reduced with respect to the heat exchange amount, and therefore, the pressure loss of the working fluid flowing inside the 1 st header 34 and the 2 nd header 35 can be suppressed, and the occurrence of liquid stagnation can be suppressed.

The heat exchanger 30 according to embodiment 1 includes one heat exchanger core 31, the 1 st header 34 is provided at the lower end of the heat exchanger core 31, and the 2 nd header 35 is provided at the upper end of the heat exchanger core 31. A hot gas refrigerant inlet 32 is formed at one end of the 1 st header 34, and a liquid refrigerant outlet 33 through which refrigerant flows out when functioning as a condenser is formed at one end of the 2 nd header 35 located on the opposite side of the one end of the 1 st header 34.

According to the heat exchanger 30 of embodiment 1, the hot gas refrigerant inlet 32 and the liquid refrigerant outlet 33 are formed at the ends of positions opposite to the 1 st header 34 and the 2 nd header 35, respectively. Therefore, the 1 st header 34 has a pressure loss Δp _1－2 Pressure loss Δp with header 2 35 _3－4 The difference becomes smaller. As a result, the flow path differential pressure DeltaP is less likely to occur _HEX The smaller area is thereby suppressed in the occurrence of liquid retention, and thus frost remaining can be suppressed.

The outdoor unit 10 of the air conditioner 100 according to embodiment 1 includes the heat exchanger 30 described above.

The air conditioner 100 according to embodiment 1 includes: the outdoor unit 10 of the air conditioner 100; an indoor unit 20 of the air conditioning apparatus 100; and a refrigerant circuit 101 configured by the outdoor unit 10 of the air conditioner 100 and the indoor unit 20 of the air conditioner 100, and configured to circulate a refrigerant.

The outdoor unit 10 of the air conditioner 100 and the air conditioner 100 according to embodiment 1 can obtain the same effects as the heat exchanger 30.

Embodiment 2

Hereinafter, although embodiment 2 will be described, the description of the portions overlapping with embodiment 1 will be omitted, and the same or corresponding portions as those in embodiment 1 will be denoted by the same reference numerals.

Fig. 14 is a graph illustrating heat exchanger performance of the heat exchanger 30 according to embodiment 2. Fig. 15 is a diagram illustrating heat exchanger performance of a modification of the heat exchanger 30 according to embodiment 2. In fig. 14 and 15, the black arrows and the white arrows indicate the flow of the refrigerant during the defrosting operation. In fig. 14 and 15, the width of each region of the heat exchanger core 31 from the downstream side is denoted by L ₁ 、L ₂ And (3) the same. Here, the downstream is the flow of the refrigerant flowing in from the hot gas refrigerant inlet 32, and the same applies hereinafter.

In the heat exchanger 30 according to embodiment 2, the partition plate 40 is provided at least in the 1 st header 34. In fig. 14, there is shown a case where one partition plate 40 is provided in the 1 st header 34, and an odd number of partition plates 40 are provided. In addition, in fig. 15, there is shown a case where one partition plate 40 is provided in the 1 st header 34, one partition plate 40 is provided in the 2 nd header 35, and an even number of partition plates 40 are provided. As shown in fig. 14, in the case where an odd number of partition plates 40 are provided, the liquid refrigerant outlet 33 is provided at an end of the 1 st header 34 opposite to the end at which the hot gas refrigerant inlet 32 is formed. In addition, as shown in fig. 15, in the case where an even number of partition plates 40 are provided, the liquid refrigerant outlet 33 is provided at the end of the 2 nd header 35 on the opposite side to the end of the 1 st header 34 where the hot gas refrigerant inlet 32 is formed.

The partition plate 40 is provided to divide the flow path of the heat exchanger core 31 into a plurality of regions in the horizontal direction. The partition plate 40 is provided so that the flow path in each region of the heat exchanger core 31 and the flow path in the adjacent region are opposed to each other. If the width of the region on the most downstream side of the heat exchanger core 31 is L ₁ To satisfy 20[%]≤L ₁ /L≤50[％]The heat exchanger 30 is configured in the manner of (a).

By providing the partition plate 40 in the 1 st header 34, the flow path cross-sectional area becomes smaller with respect to the same refrigerant flow rate, and therefore the refrigerant flow rate increases, but on the other hand, the pressure loss increases. Therefore, consider the refrigerationThe balance between the improvement of heat exchanger performance due to the increase of the heat transfer rate by the increase of the agent flow rate and the decrease of heat exchanger performance due to the increase of the pressure loss is that the heat exchanger performance is set to 90[%]Above, thus to satisfy 20[%]≤L ₁ /L≤50[％]The heat exchanger 30 is configured in the manner of (a). This can improve the heat exchanger performance as compared with the case where the partition plate 40 is not provided in the 1 st header 34. Further, the occurrence of liquid retention during defrosting operation is suppressed by the increase in pressure loss, and thus frost remaining can be suppressed. As a result, the defrosting performance at the time of defrosting operation can be improved. Further, as shown in fig. 14 and 15, it is found from the experiments of the inventors that the composition satisfies 20[% ]≤L ₁ /L≤50[％]The heat exchanger 30 is constructed in such a manner that the heat exchanger performance can be improved by 10% at maximum]Left and right.

As described above, the heat exchanger 30 according to embodiment 2 is the heat exchanger 30 including one heat exchanger core 31, the 1 st header 34 is provided at the lower end portion of the heat exchanger core 31, and the 2 nd header 35 is provided at the upper end portion of the heat exchanger core 31. The heat exchanger 30 includes a partition plate 40, and the partition plate 40 is provided at least in the 1 st header 34 and partitions the flow path of the heat exchanger core 31 into a plurality of regions in the width direction. Further, the width of the heat exchanger core 31 of the heat exchanger 30 is defined as Lm]The width of the region on the most downstream side of the heat exchanger core 31 is defined as L ₁ In the case of (2), 20[%]≤L ₁ /L≤50[％]。

According to the heat exchanger 30 according to embodiment 2, the heat exchanger is configured to satisfy 20[%]≤L ₁ /L≤50[％]. Therefore, the heat exchanger performance can be improved as compared with the case where the partition plate 40 is not provided in the 1 st header 34. Further, the occurrence of liquid retention during defrosting operation is suppressed by the increase in pressure loss, and thus frost remaining can be suppressed. As a result, the defrosting performance at the time of defrosting operation can be improved.

Embodiment 3

Hereinafter, embodiment 3 will be described, but the description of the portions overlapping with embodiments 1 and 2 will be omitted, and the same reference numerals will be given to the same or corresponding portions as those of embodiments 1 and 2.

Fig. 16 is a perspective view schematically showing a heat exchanger 30 according to embodiment 3. Fig. 17 is an enlarged view of the periphery of the cross-row header 50 of the heat exchanger 30 according to embodiment 3. In fig. 16, only the flat tubes 38 at the ends of the heat exchanger core 31 are illustrated to prevent complication of the drawing. In fig. 16, the black arrows indicate the flow of air through the heat exchanger 30, and the broken arrows and the white arrows indicate the flow of refrigerant during the defrosting operation. In addition, the white arrows in fig. 17 indicate the flow of the refrigerant

As shown in fig. 16, in the heat exchanger 30 according to embodiment 3, two heat exchanger cores 31 are arranged side by side in the air flow direction. Further, upper ends of both of the two rows of heat exchanger cores 31, which are juxtaposed in the flow direction of the air, are connected to the cross-row header 50. The lower end portion on the leeward side of the two rows of heat exchanger cores 31 is connected to the 1 st header 34, and the lower end portion on the windward side of the two rows of heat exchanger cores 31 is connected to the 2 nd header 35. In the defrosting operation, the hot gas refrigerant flowing into the 1 st header 34 flows as an upward flow through the flat tubes 38 of the heat exchanger core 31 disposed on the leeward side, is folded back at the straddling headers 50, flows as a downward flow through the flat tubes 38 of the heat exchanger core 31 disposed on the windward side, and flows out of the 2 nd header 35. That is, the straddling headers 50 are provided at one end of the adjacent two heat exchanger cores 31, and distribute the refrigerant merged from the flat tubes 38 of the heat exchanger core 31 on the leeward side to the flat tubes 38 of the heat exchanger core 31 on the windward side.

In this way, by disposing two heat exchanger cores 31 side by side in the air flow direction and providing the cross-row header 50 at one end of the two heat exchanger cores, the refrigerant flow path, which is the sum of the heights of the two heat exchanger cores 31, can be extended. Therefore, the flow path differential pressure Δp can be increased _HEX . As a result, ΔP can be increased _HEX /ΔP _HEAD Thus, liquid stagnation is suppressed, and therefore, defrosting performance during defrosting operation can be improved. Here, in embodiment 3, the flow path differential pressure Δp _HEX Is downwind ofDifferential pressure between the lower ends of the flat tubes 38 of the side heat exchanger core 31 and the lower ends of the flat tubes 38 of the upstream side heat exchanger core 31 (differential pressure between position (1) and position (4) in fig. 16) P _1－4 。

Further, as shown in fig. 17, when the gap between the upper end portion of the flat tube 38 inserted into the straddling header 50 and the wall portion 51 of the straddling header 50 facing the upper end portion of the flat tube 38 is δ, the upper end portion of the flat tube 38 is inserted into the straddling header 50 such that δ is 3 mm or less, preferably δ is 1 mm or less.

Thus, the differential pressure P inside the cross-row header 50 _2－3 (the differential pressure between position (2) and position (3) in FIG. 16) increases, and therefore the flow path differential pressure ΔP increases _HEX ＝P _1－4 This can suppress the occurrence of liquid retention.

FIG. 18 shows the gap delta and differential pressure delta P of the heat exchanger based on the experimental results _2－3 Is a graph of the relationship of (1). Fig. 18 shows the differential pressure P inside the cross-row header 50 in the case where the gap δ between the upper end portion of the flat tube 38 and the wall portion 51 of the cross-row header 50 is changed based on the simulation of the inventor _2－3 Is an example of the above.

As shown in fig. 18, by reducing the gap δ, the differential pressure Δp _2－3 And gradually increases as an exponential function. In general, the heat exchanger performance is improved by increasing the gap δ, but may be set to δ.ltoreq.3 [ mm ] in consideration of the occurrence of liquid retention]Preferably, delta is less than or equal to 1[ mm ]]. In this way, even in consideration of the influence of the pressure loss, the occurrence of liquid retention can be suppressed, and the heat exchanger performance can be improved.

Fig. 19 is a schematic side view of a heat exchanger 30 according to embodiment 3. In fig. 16, the black arrows indicate the flow of air through the heat exchanger 30, and the white arrows indicate the flow of refrigerant.

In general, the fan 13 is stopped in order to suppress heat leakage from the heat exchanger 30 to the air during defrosting operation, but there are cases where a pushed-in airflow is generated to the heat exchanger 30 due to an influence of external wind or the like. In this case, as shown in fig. 19, the 1 st header 34 having the hot gas refrigerant inlet 32 formed therein is disposed on the leeward side, and the 2 nd header 35 having the liquid refrigerant outlet 33 formed therein is disposed on the windward side. This reduces the difference between the temperature of the refrigerant and the temperature of the air in the flat tubes 38 of the heat exchanger core 31 on the leeward side, which is an upward flow in the vertical direction, and thus can suppress the occurrence of liquid stagnation in the heat exchanger core 31 on the leeward side. As shown in fig. 19, the flow of the refrigerant in the leeward heat exchanger core 31 and the flow of the refrigerant in the windward heat exchanger core 31 are opposite to each other. Therefore, even when the pushed-in air flow is generated in the heat exchanger 30 due to the influence of external wind or the like, the temperature of the air can be raised in the flat tubes 38 of the heat exchanger core 31 on the windward side. Further, the difference between the temperature of the refrigerant and the temperature of the air in the flat tubes 38 of the leeward heat exchanger core 31 becomes small, and therefore, the occurrence of liquid stagnation in the leeward heat exchanger core 31 can be suppressed.

In the heat exchanger 30 of embodiment 3, two heat exchanger cores 31 are arranged side by side in the air flow direction, but the present invention is not limited to this, and three or more heat exchanger cores 31 may be arranged side by side in the air flow direction. In this case, the heat exchanger 30 is configured to include the number-1 of the cross-row headers 50 of the heat exchanger cores 31. For example, in the case where three heat exchanger cores 31 are arranged side by side in the flow direction of air, the 1 st header 34 is provided at the lower end portion of the heat exchanger core 31 located on the most leeward side, and the 2 nd header 35 is provided at the upper end portion of the heat exchanger core 31 located on the most windward side. Further, a cross-row header 50 is provided at each of the upper end portions of the heat exchanger core 31 on the most leeward side and the heat exchanger core 31 in the middle adjacent thereto, and the lower end portions of the heat exchanger core 31 on the most windward side adjacent thereto.

As described above, the heat exchanger 30 according to embodiment 3 includes two or more heat exchanger cores 31 along the flow direction of air, and the 1 st header 34 is provided at the lower end portion of the heat exchanger core 31 located on the most windward side, the 2 nd header 35 is provided at the upper end portion or the lower end portion of the heat exchanger core 31 located on the most windward side, the hot gas refrigerant inlet 32 is formed at one end of the 1 st header 34, and the liquid refrigerant outlet 33 is formed at one end of the 2 nd header 35 located on the same side as one end of the 1 st header 34. The heat exchanger 30 further includes a cross-row header 50 provided at the upper end or the lower end of the two adjacent heat exchanger cores 31, and distributes the refrigerant merged from each of the flat tubes 38 of the heat exchanger core 31 on the leeward side to each of the flat tubes 38 of the heat exchanger core 31 on the windward side.

According to the heat exchanger 30 of embodiment 3, since the cross-row header 50 for distributing the refrigerant, which merges from the flat tubes 38 of the heat exchanger core 31 located on the leeward side, to the flat tubes 38 of the heat exchanger core 31 located on the windward side is provided, the refrigerant flow path, which is the sum of the heights of two or more heat exchanger cores 31, can be extended, and therefore the flow path differential pressure Δp can be increased _HEX . As a result, ΔP can be increased _HEX /ΔP _HEAD Thus, liquid stagnation is suppressed, and therefore, defrosting performance during defrosting operation can be improved.

In the heat exchanger 30 according to embodiment 3, the upper end or the lower end of each flat tube 38 of the adjacent two heat exchanger cores 31 is inserted into the cross-row header 50. When the gap between the upper end or lower end of the flat tube 38 and the wall 51 of the header 50 facing the upper end or lower end is defined as δ, the heat exchanger 30 satisfies δ.ltoreq.3 [ mm ].

According to the heat exchanger 30 of embodiment 3, since δ is set to be equal to or smaller than 3[ mm ], the occurrence of liquid stagnation can be suppressed even in consideration of the influence of pressure loss, and the heat exchanger performance can be improved.

Embodiment 4

Hereinafter, embodiment 4 will be described, but the description of the portions overlapping with embodiments 1 to 3 will be omitted, and the same reference numerals will be given to the same or corresponding portions as those in embodiments 1 to 3.

Fig. 20 is a refrigerant circuit diagram of the outdoor unit 10 of the air conditioner 100 including the heat exchanger 30 according to embodiment 4. The white arrows in fig. 20 indicate the flow of the refrigerant during the defrosting operation.

As shown in fig. 20, the outdoor unit 10 of the air conditioner 100 according to embodiment 4 includes a plurality of heat exchangers 30a to 30c. The heat exchangers 30a to 30c are any of the heat exchangers 30 described in embodiments 1 to 3. The number of the heat exchangers 30a to 30c included in the outdoor unit 10 of the air conditioner 100 is not limited to three, but may be at least two.

The outlet side of the heat exchanger 30a and the outlet side of the heat exchanger 30b are configured to merge at the 1 st merging portion 63 a. The outlet side of the 1 st merging portion 63a and the outlet side of the heat exchanger 30c are merged at the 2 nd merging portion 63 b. The 1 st throttle 62a is provided in the refrigerant pipe between the 1 st merging portion 63a and the 2 nd merging portion 63 b. A 2 nd expansion device 62b is provided in the refrigerant pipe between the outlet of the heat exchanger 30c and the 2 nd merging portion 63 b. A 1 st on-off valve 61a is provided in the refrigerant piping between the branching point on the inlet side of the heat exchangers 30a to 30c and the inlet of the heat exchanger 30c. A 2 nd opening/closing valve 61b is provided in the refrigerant pipe connecting the inlet of the heat exchanger 30c and the 1 st merging portion 63a and the 1 st throttling device 62a. The 1 st opening/closing valve 61a and the 2 nd opening/closing valve 61b may be valves whose opening degree can be adjusted, not only the valves that are opened and closed. Hereinafter, the 1 st throttle device 62a and the 2 nd throttle device 62b are collectively referred to as throttle devices, and the 1 st on-off valve 61a and the 2 nd on-off valve 61b are collectively referred to as on-off valves.

The air conditioner 100 further includes a control device 70 that controls a throttle device, an on-off valve, and the like. The control device 70 is configured by, for example, dedicated hardware or a CPU (Central Processing Unit, also referred to as a central processing unit, a processing unit, an arithmetic unit, a microprocessor, or a processor) that executes a program stored in a storage unit (not shown). The control device 70 may be provided in the outdoor unit 10 or in the indoor unit 20.

In the case where the control device 70 is dedicated hardware, the control device 70 corresponds to, for example, a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit ), an FPGA (Field-Programmable Gate Array, field programmable gate array), or a combination of these. Each of the functional units realized by the apparatus 70 may be realized by separate hardware, or each functional unit may be realized by one hardware.

In the case where the control device 70 is a CPU, each function executed by the control device 70 is implemented by software, firmware, or a combination of software and firmware. The software and firmware are described as programs and stored in the storage unit. The CPU reads out and executes the program stored in the storage unit to realize the functions of the control device 70. Here, the storage unit stores various information, for example, a nonvolatile semiconductor memory including rewritable data such as a flash memory, an EPROM, and an EEPROM.

In addition, a part of the functions of the control device 70 may be realized by dedicated hardware, and a part may be realized by software or firmware.

The constitution is as follows: in defrosting operation, the flow path differential pressure Δp is set to be equal to or smaller than the flow path differential pressure Δp _HEX Becomes the liquid pressure head delta P _HEAD As described above, the flow of the refrigerant in some of the heat exchangers 30a to 30c is connected in series with the flow of the refrigerant in the other heat exchangers, and the flows of the refrigerant in the other heat exchangers are connected in parallel. Specifically, the control device 70 opens the 2 nd opening/closing valve 61b and closes the 1 st opening/closing valve 61a. When the heat exchangers 30a to 30c function as evaporators during heating operation or the like, the heat exchangers 30a to 30c are configured such that the flows of the refrigerant are connected in parallel. Specifically, the control device 70 closes the 2 nd opening/closing valve 61b and opens the 1 st opening/closing valve 61a.

In this way, during defrosting operation, the flow of the refrigerant in some of the heat exchangers 30a to 30c and the flow of the refrigerant in the other heat exchangers are connected in series, and the flows of the refrigerant in the other heat exchangers are connected in parallel, so that the flow path cross-sectional area is reduced with respect to the same refrigerant flow rate. Therefore, the flow velocity of the hot gas refrigerant in the flow path that becomes the upward flow increases, and the flow path differential pressure Δp can be increased _HEX Therefore, liquid stagnation can be suppressedAnd is left, thereby improving the defrosting performance during defrosting operation. When the heat exchangers 30a to 30c function as evaporators, the heat exchangers 30a to 30c are configured such that the flows of the refrigerants are connected in parallel, and the flow path cross-sectional area is increased with respect to the same refrigerant flow rate, so that the pressure loss is reduced, and the heating capacity can be improved.

As described above, the air conditioner 100 according to embodiment 4 includes the outdoor unit 10, and the outdoor unit 10 includes the plurality of heat exchangers 30a to 30c, and the air conditioner 100 includes the control device 70, and the control device 70 is configured to connect some of the plurality of heat exchangers 30a to 30c in series with the other heat exchangers 30a to 30c during defrosting operation, and to connect the flows of the refrigerant in the heat exchangers 30a to 30c in parallel when the heat exchangers 30a to 30c function as evaporators.

According to the air conditioner 100 of embodiment 4, during defrosting operation, the flow of the refrigerant in some of the heat exchangers 30a to 30c and the flow of the refrigerant in the other heat exchangers are connected in series, and the flows of the refrigerant in the other heat exchangers are connected in parallel, so that the flow path cross-sectional area is reduced with respect to the same refrigerant flow rate. Therefore, the flow velocity of the hot gas refrigerant in the flow path that becomes the upward flow increases, and the flow path differential pressure Δp can be increased _HEX Therefore, liquid retention is suppressed, and defrosting performance during defrosting operation can be improved. When the heat exchangers 30a to 30c function as evaporators, the heat exchangers 30a to 30c are configured such that the flows of the refrigerants are connected in parallel, and the flow path cross-sectional area is increased with respect to the same refrigerant flow rate, so that the pressure loss is reduced, and the heating capacity can be improved.

Embodiment 5

Hereinafter, embodiment 5 will be described, but the description of the portions overlapping with embodiments 1 to 4 will be omitted, and the same reference numerals will be given to the same or corresponding portions as those in embodiments 1 to 4.

Fig. 21 is a refrigerant circuit diagram of the outdoor unit 10 of the air conditioner 100 including the heat exchanger 30 according to embodiment 5. The white arrows in fig. 21 indicate the flow of the refrigerant during the defrosting operation.

As shown in fig. 21, the outdoor unit 10 of the air conditioner 100 according to embodiment 5 includes a plurality of heat exchangers 30a to 30c. The heat exchangers 30a to 30c are any of the heat exchangers 30 described in embodiments 1 to 3. The number of the heat exchangers 30a to 30c included in the outdoor unit 10 of the air conditioner 100 is not limited to three, but may be at least two.

In embodiment 5, a 3 rd on-off valve 61c is provided in the refrigerant pipe between the branching point on the inlet side of the heat exchangers 30a to 30b and the inlet of the heat exchanger 30 b. Other structures are the same as those of the refrigerant circuit 101 described in embodiment 4, and therefore, description thereof is omitted.

In addition, the flow path differential pressure Δp is configured to be set during defrosting operation _HEX Becomes the liquid pressure head delta P _HEAD As described above, the flow of the refrigerant in some of the heat exchangers 30a to 30c is connected in series with the flow of the refrigerant in the other heat exchangers, and the flows of the refrigerant in the other heat exchangers are connected in parallel. Specifically, the control device 70 opens the 2 nd on-off valve 61b and the 3 rd on-off valve 61c, and closes the 1 st on-off valve 61a. Further, by fully closing the throttle device or the on-off valve, at least one of the heat exchangers 30a to 30c configured in parallel is prevented from flowing into the refrigerant, and the other heat exchangers 30a to 30c are preferably subjected to the defrosting operation. The heat exchangers 30a to 30c that perform defrosting operation are switched by switching the throttle device or the on-off valve that is fully closed. The timing of switching the heat exchangers 30a to 30c that perform the defrosting operation preferentially by switching the throttle device or the on-off valve that is fully closed is to provide a temperature sensor such as a thermistor after a predetermined time has elapsed or to the outlet side of each of the heat exchangers 30a to 30c, and to detect the temperature or the like based on the temperature sensor.

When the heat exchangers 30a to 30c function as evaporators during heating operation or the like, the heat exchangers 30a to 30c are configured such that the flows of the refrigerant are connected in parallel. Specifically, the control device 70 closes the 2 nd on-off valve 61b, and opens the 1 st on-off valve 61a and the 3 rd on-off valve 61c, respectively.

In this way, during defrosting operation, the flow of the refrigerant in some of the heat exchangers 30a to 30c and the flow of the refrigerant in the other heat exchangers are connected in series, and the flows of the refrigerant in the other heat exchangers are connected in parallel. As a result, the flow path cross-sectional area becomes smaller than the same refrigerant flow rate, and therefore the flow velocity of the refrigerant in the flow path in which the hot gas refrigerant flows upward increases, and the flow path differential pressure Δp can be increased _HEX . At least one of the heat exchangers 30a to 30c configured such that the flow of the refrigerant is parallel is subjected to the defrosting operation preferentially, and then the heat exchangers 30a to 30c subjected to the defrosting operation preferentially are sequentially switched, whereby the frost remaining can be reduced. Therefore, liquid retention can be further suppressed, and the defrosting performance at the time of defrosting operation can be further improved. When the heat exchangers 30a to 30c function as evaporators, the heat exchangers 30a to 30c are configured such that the flows of the refrigerants are connected in parallel, and the flow path cross-sectional area is increased with respect to the same refrigerant flow rate, so that the pressure loss is reduced and the heating capacity can be improved.

As described above, in the air conditioner 100 according to embodiment 5, the control device 70 is configured to connect the flow of the refrigerant in some of the plurality of heat exchangers 30a to 30c and the flow of the refrigerant in the other heat exchangers 30a to 30c in series, and to connect the flows of the refrigerant in the other heat exchangers in parallel, and to make at least one heat exchanger not flow in the refrigerant when the plurality of heat exchangers 30a to 30c configured to connect the flows of the refrigerant in parallel are used in the defrosting operation, thereby preferentially performing the defrosting operation on the other heat exchangers 30a to 30 c.

According to the air conditioner 100 of embodiment 5, at least one of the heat exchangers 30a to 30c configured to be connected in parallel with the flow of the refrigerant is subjected to the defrosting operation preferentially, and then the heat exchangers 30a to 30c subjected to the defrosting operation preferentially are sequentially switched, whereby the frost remaining can be reduced. Therefore, liquid retention can be further suppressed, and the defrosting performance at the time of defrosting operation can be further improved.

Embodiment 6

Hereinafter, embodiment 6 will be described, but the description of the portions overlapping with embodiments 1 to 5 will be omitted, and the same reference numerals will be given to the same or corresponding portions as those in embodiments 1 to 5.

Fig. 22 is a schematic cross-sectional view of the flat tube 38 of the heat exchanger 30 according to embodiment 6. Fig. 23 is a schematic cross-sectional view of a flat tube 38 of a modification of the heat exchanger 30 according to embodiment 6. Fig. 24 is a schematic side view of a flat tube 38 of a modification of the heat exchanger 30 according to embodiment 6.

As shown in fig. 22, the flat tubes 38 of the heat exchanger 30 are internally provided with a plurality of partition columns 38a. The partition columns 38a are arranged along the longitudinal direction of the cross section of the flat tube 38, and extend along the longitudinal direction of the flat tube 38 to partition the interior of the flat tube 38 into a plurality of spaces. And is a grooved flat tube in which a plurality of inwardly projecting convex portions 38b are provided between adjacent partition columns 38a. The protruding portions 38b extend in the longitudinal direction of the flat tube 38. Alternatively, as shown in fig. 23 and 24, the flat tubes 38 of the heat exchanger 30 are front-end flat tube-contracted tubes in which one front end portion 38c is contracted so that the outer diameter thereof is reduced toward the front end.

In this way, the flat tubes 38 of the heat exchanger 30 are formed as grooved flat tubes or front-end contracted flat tubes. As a result, the flow path cross-sectional area becomes smaller than the same refrigerant flow rate, and therefore the flow velocity of the refrigerant in the flow path in which the hot gas refrigerant flows upward increases, and the flow path differential pressure Δp can be increased _HEX Therefore, liquid retention can be suppressed, and defrosting performance during defrosting operation can be improved.

As described above, in the heat exchanger 30 according to embodiment 6, the flat tube 38 is provided with the plurality of partition columns 38a that partition the flow path inside, the plurality of partition columns 38a are provided inside, the convex portions 38b that protrude inward are provided between the adjacent partition columns 38a, or the flat tube 38 is subjected to the tube shrinkage process on the front end portion 38c so that the outer diameter is reduced toward the front end.

According to the heat exchanger 30 of embodiment 6, the flat tubes 38 are in phaseA plurality of projections 38b are formed along the flow path between adjacent partition columns 38a, or the flat tube 38 is contracted at the distal end portion 38c so that the outer diameter thereof is reduced toward the distal end. By forming the flat tubes 38 as grooved flat tubes or front end contracted flat tubes in this manner, the flow path cross-sectional area is reduced for the same refrigerant flow rate, and therefore the flow velocity of the refrigerant in the flow path in which the hot gas refrigerant flows upward is increased, and the flow path differential pressure Δp can be increased _HEX . As a result, liquid retention can be suppressed, and defrosting performance during defrosting operation can be improved.

Embodiment 7

Hereinafter, embodiment 7 will be described, but the description of the portions overlapping with embodiments 1 to 6 will be omitted, and the same reference numerals will be given to the same or corresponding portions as those in embodiments 1 to 6.

Fig. 25 shows the type and Δp of the refrigerant used in the refrigerant circuit 101 of the air conditioner 100 according to embodiment 7 _HEX /ΔP _HEAD Is a graph of the relationship of (1).

As can be seen from fig. 25, Δp is calculated in any one of pure refrigerants including HFO1123, HFO1132 (E), R1234yf, R1234ze (E), R1234ze (Z), R1233zd (E), propane (R290), and fluoroethane (R161) _HEX /ΔP _HEAD Are improved over the pure refrigerants of R32 and R410A.

Therefore, in embodiment 7, as the refrigerant circulating in the refrigerant circuit 101 of the air conditioner 100, any one of pure refrigerants including HFO1123, HFO1132 (E), R1234yf, R1234ze (E), R1234ze (Z), R1233zd (E), propane (R290), and fluoroethane (R161) is used.

By using the pure refrigerant as described above as the refrigerant circulating in the refrigerant circuit 101 of the air conditioner 100 in this way, Δp can be increased _HEX /ΔP _HEAD . Therefore, the occurrence of liquid retention can be suppressed, and the heat exchanger performance can be improved.

As described above, in the air conditioner 100 according to embodiment 7, the refrigerant is any one of pure refrigerants including HFO1123, HFO1132 (E), R1234yf, R1234ze (E), R1234ze (Z), R1233zd (E), propane (R290), and fluoroethane (R161).

According to the air conditioner 100 according to embodiment 7, since the pure refrigerant described above is used as the refrigerant circulating in the refrigerant circuit 101, Δp can be increased _HEX /ΔP _HEAD . Therefore, the occurrence of liquid retention can be suppressed, and the heat exchanger performance can be improved.

Embodiment 8

Hereinafter, embodiment 8 will be described, but the description of the portions overlapping with embodiments 1 to 7 will be omitted, and the same reference numerals will be given to the same or corresponding portions as those in embodiments 1 to 8.

Fig. 26 is a front view of the heat exchanger 30 of the air conditioner 100 according to embodiment 2. The white arrows in fig. 26 indicate the flow of the refrigerant during the cooling operation. Fig. 26 shows the height H and width L of the heat exchanger core 31, and the width of each region of the heat exchanger core 31 is denoted by L from the downstream side ₁ 、L ₂ 、……。

The heat exchanger 30 according to embodiment 8 functions as a condenser that radiates heat of the refrigerant to the outdoor air and condenses the refrigerant during the cooling operation. As shown in fig. 26, the heat exchanger 30 includes a heat exchanger core 31, and the heat exchanger core 31 includes a plurality of flat tubes 38 and a plurality of fins 39. The flat tubes 38 are arranged in parallel in the horizontal direction (the left-right direction in fig. 26) with a gap therebetween so that wind generated by the fan 13 flows, and the refrigerant flows in the vertical direction in the tube extending in the vertical direction (the up-down direction in fig. 26). The fins 39 are connected so as to extend between adjacent flat tubes 38, and conduct heat to the flat tubes 38. The fins 39 improve the heat exchange efficiency between the air and the refrigerant, and for example, corrugated fins are used. However, the present invention is not limited thereto. Since heat exchange between the air and the refrigerant is performed on the surfaces of the flat tubes 38, the fins 39 may be omitted.

A hot gas refrigerant inlet 32 is formed at one end of the 2 nd header 35, and the hot gas refrigerant inlet 32 is connected to the refrigerant circuit 101 of the air conditioner 100 via a gas pipe 37. A liquid refrigerant outlet 33 is formed at the other end of the 2 nd header 35, and the liquid refrigerant outlet 33 is connected to the refrigerant circuit 101 of the air conditioner 100 via a liquid pipe 36. The 2 nd header 35 flows the high-temperature and high-pressure gas refrigerant from the compressor 11 into the heat exchanger 30 at the time of the cooling operation, and flows the low-temperature and high-pressure liquid refrigerant after heat exchange in the heat exchanger 30 out of the refrigerant circuit 101. The 2 nd header 35 allows a low-temperature low-pressure two-phase refrigerant to flow into the heat exchanger 30 during the heating operation, and allows a low-temperature low-pressure gas refrigerant after heat exchange in the heat exchanger 30 to flow out of the refrigerant circuit 101.

In the heat exchanger 30 according to embodiment 8, as shown in fig. 26, a partition plate 40 is provided in the 2 nd header 35. The partition plate 40 is provided to divide the flow path of the heat exchanger core 31 into a plurality of regions in the horizontal direction. The partition plate 40 is provided so that the flow path in each region of the heat exchanger core 31 and the flow path in the adjacent region are opposed to each other. In embodiment 8, the flow of the heat exchanger core 31 is divided into two regions T by the partition plate 40 ₁ 、T ₂ . Further, by providing the partition plate 40 in the 2 nd header 35, the merging region M of the hot gas refrigerant is formed in the 1 st header 34 ₁ 。

The hot gas refrigerant flowing into the 2 nd header 35 is disposed in the region T ₁ Flows as a downward flow through the flat tubes 38 of the heat exchanger core 31 in the 1 st header 34 in the merging region M ₁ Is merged at the region T ₂ Flows as an upward flow through the flat tubes 38 of the heat exchanger core 31, and then flows out of the header 2 35. Namely, region T ₁ For downflow zone, zone T ₂ Is an upflow region. In addition, the 1 st header 34 merges Region M ₁ The hot gas refrigerant inflow portion for the upward flow region.

In region T ₂ In the meantime, when the hot gas refrigerant flows as an upward flow through the flat tubes 38 of the heat exchanger core 31, liquid retention occurs in which the liquefied refrigerant cannot rise and remain under the influence of gravity. Therefore, in the heat exchanger 30 according to embodiment 8, the heat exchanger is disposed in the region T to be the upflow region ₂ The number of the flat tubes 38 of the heat exchanger core 31 is N _r [ root of Fabry-Perot ]]Region T at the time ₂ The total flow path cross-sectional area of the heat exchanger core 31 in (a) is defined as a _r [m ² ]＝a×N _r [m ² ]The height of the heat exchanger core 31 is defined as Hm]The differential pressure of the refrigerant flow path is defined as Δp _HEX The liquid head is defined as ΔP _HEAD In the case of (1), satisfy ΔP _HEX /ΔP _HEAD ＝(5.94635×10 ^－4 ×A _r ^－1.75030 ) /(8.4303H+0.8779) > 1. By configuring the heat exchanger 30 in this manner, the refrigerant flowing in from the hot gas refrigerant inlet 32 formed in the upper portion of the heat exchanger 30 flows in the region T ₂ When flowing as an upward flow through the flat tubes 38 of the heat exchanger core 31, the occurrence of liquid retention in which the liquefied refrigerant cannot rise and remains due to the influence of gravity can be suppressed, and the decrease in defrosting performance can be suppressed. In addition, by providing the partition plate 40 in the 2 nd header 35, the flow path cross-sectional area is reduced for the same refrigerant flow rate, and therefore the refrigerant flow rate is increased, and the flow path differential pressure Δp can be increased _HEX Therefore, liquid retention can be suppressed, and defrosting performance during defrosting operation can be improved.

Embodiment 9

Hereinafter, embodiment 9 will be described, but the description of the portions overlapping with embodiments 1 to 8 will be omitted, and the same reference numerals will be given to the same or corresponding portions as those in embodiments 1 to 8.

Fig. 27 is a front view of the heat exchanger 30 of the air conditioner 100 according to embodiment 9. The white arrows in fig. 27 indicate the flow of the refrigerant during the cooling operation. In addition, fig. 27 shows the height H of the heat exchanger core 31And a width L, the width of each region of the heat exchanger core 31 from the downstream side being denoted as L ₁ 、L ₂ 、……。

The heat exchanger 30 according to embodiment 9 functions as a condenser that radiates heat of the refrigerant to the outdoor air and condenses the refrigerant during the cooling operation. As shown in fig. 27, the heat exchanger 30 includes a heat exchanger core 31, and the heat exchanger core 31 includes a plurality of flat tubes 38 and a plurality of fins 39. The flat tubes 38 are arranged in parallel in the horizontal direction (left-right direction in fig. 27) with a gap therebetween so that wind generated by the fan 13 flows, and the refrigerant flows in the vertical direction in the tube extending in the vertical direction (up-down direction in fig. 27). The fins 39 are connected so as to extend between adjacent flat tubes 38, and conduct heat to the flat tubes 38. The fins 39 improve the heat exchange efficiency between the air and the refrigerant, and for example, corrugated fins are used. However, the present invention is not limited thereto. Since heat exchange between the air and the refrigerant is performed on the surfaces of the flat tubes 38, the fins 39 may be omitted.

A hot gas refrigerant inlet 32 is formed at one end of the 2 nd header 35, and the hot gas refrigerant inlet 32 is connected to the refrigerant circuit 101 of the air conditioner 100 via a gas pipe 37. The 2 nd header 35 flows the high-temperature and high-pressure gas refrigerant from the compressor 11 into the heat exchanger 30 during the cooling operation, and flows the low-temperature and low-pressure gas refrigerant after heat exchange in the heat exchanger 30 out of the refrigerant circuit 101 during the heating operation.

A liquid refrigerant outlet 33 is formed at one end of the 1 st header 34 on the opposite side of the 2 nd header 35, and the liquid refrigerant outlet 33 is connected to the refrigerant circuit 101 of the air conditioner 100 via a liquid pipe 36. The 1 st header 34 flows the low-temperature low-pressure two-phase refrigerant into the heat exchanger 30 during the heating operation, and flows the low-temperature high-pressure liquid refrigerant after heat exchange in the heat exchanger 30 out of the refrigerant circuit 101 during the cooling operation.

As shown in fig. 27, in the heat exchanger 30 according to embodiment 9, the partition plate 40 is provided in each of the 1 st header 34 and the 2 nd header 35. The partition plate 40 is provided to divide the flow path of the heat exchanger core 31 into a plurality of regions in the horizontal direction. The partition plate 40 is provided so that the flow path in each region of the heat exchanger core 31 and the flow path in the adjacent region are opposed to each other. In embodiment 3, the flow path of the heat exchanger core 31 is divided into three regions T by two dividing plates 40 ₁ 、T ₂ 、T ₃ . Further, by providing the partition plates 40 in the 1 st header 34 and the 2 nd header 35, respectively, the merging regions M of the hot gas refrigerants are formed in the 1 st header 34 and the 2 nd header 35, respectively ₁ 、M ₂ 。

The hot gas refrigerant flowing into the 2 nd header 35 is disposed in the region T ₁ Flows as a downward flow through the flat tubes 38 of the heat exchanger core 31 in the 1 st header 34 in the merging region M ₁ Is merged and arranged in the region T ₂ Flows as an upward flow in the flat tubes 38 of the heat exchanger core 31. Thereafter, the hot gas refrigerant merges at the merging region M of the 2 nd header 35 ₂ Is merged at the region T ₃ Flows as a downflow through the flat tubes 38 of the heat exchanger core 31, and flows out of the 1 st header 34. Namely, region T ₁ Region T ₃ For downflow zone, zone T ₂ Is an upflow region. In addition, the merging region M of the 1 st header 34 ₁ The hot gas refrigerant inflow portion for the upward flow region.

In region T ₂ In the meantime, when the hot gas refrigerant flows as an upward flow through the flat tubes 38 of the heat exchanger core 31, liquid retention occurs in which the liquefied refrigerant cannot rise and remain under the influence of gravity. Therefore, the heat exchanger 30 according to embodiment 9 is to be disposed asZone T of the upflow zone ₂ The number of the flat tubes 38 of the heat exchanger core 31 is N _r [ root of Fabry-Perot ]]Region T at the time ₂ The total flow path cross-sectional area of the heat exchanger core 31 in (a) is defined as a _r [m ² ]＝a×N _r [m ² ]The height of the heat exchanger core 31 is defined as Hm]The differential pressure of the refrigerant flow path is defined as Δp _HEX The liquid head is defined as ΔP _HEAD In the case of (1), satisfy ΔP _HEX /ΔP _HEAD ＝(5.94635×10 ^－4 ×A _r ^－1.75030 ) /(8.4303H+0.8779) > 1. By configuring the heat exchanger 30 in this manner, the refrigerant flowing in from the hot gas refrigerant inlet 32 formed in the upper portion of the heat exchanger 30 flows in the region T ₂ When flowing as an upward flow through the flat tubes 38 of the heat exchanger core 31, the occurrence of liquid retention in which the liquefied refrigerant cannot rise and remains due to the influence of gravity can be suppressed, and the decrease in defrosting performance can be suppressed. Further, by providing the partition plates 40 in each of the 1 st header 34 and the 2 nd header 35, the flow path cross-sectional area becomes smaller for the same refrigerant flow rate, and therefore the refrigerant flow rate increases, and the flow path differential pressure Δp can be increased _HEX Therefore, liquid retention can be suppressed, and defrosting performance during defrosting operation can be improved.

Description of the reference numerals

An outdoor unit; a compressor; flow path switching device; fan; indoor unit; a throttle device; indoor heat exchanger; indoor fan; heat exchanger; heat exchanger; heat exchanger; heat exchanger; heat exchanger core; hot gas refrigerant inlet; a liquid refrigerant outlet; header 1; header 2; liquid piping; gas piping; flat tube; partition columns; protrusion; front end; fins; 40. the separator plate; cross-column header; 51. wall sections; first opening/closing valve 1; a 2 nd opening/closing valve; a 3 rd on-off valve; 1 st restriction; 2 nd throttle device; a 1 st junction; 2. Confluence; control means; air conditioning apparatus; refrigerant circuit.

Claims

1. A heat exchanger mounted in an outdoor unit of an air conditioner, the heat exchanger comprising one heat exchanger core or two or more heat exchanger cores extending in a direction of air flow, the heat exchanger core comprising a plurality of flat tubes extending in a vertical direction, wherein when the heat exchanger functions as a condenser, a refrigerant flows as an upward flow inside the flat tubes,

The heat exchanger is characterized in that,

the flow path cross-sectional area of each flat tube is defined as a [ m ] ² ]The number of the flat tubes is N]The total flow path cross-sectional area of the heat exchanger core is defined as Am ² ]＝a×N[m ² ]The height of the heat exchanger core is defined as Hm]The differential pressure of the refrigerant flow path is defined as Δp _HEX The liquid head is defined as ΔP _HEAD In the case of (a) the number of the cells,

satisfy DeltaP _HEX /ΔP _HEAD ＝(5.94635×10 ^－4 ×A ^－1.75030 )/(8.4303H+0.8779)＞1。

2. A heat exchanger according to claim 1 wherein,

when the heat exchanger functions as a condenser, a hot gas refrigerant inlet is formed at a lower portion of the heat exchanger.

3. A heat exchanger according to claim 1 wherein,

when the heat exchanger functions as a condenser, a merging region of hot gas refrigerants is formed at a lower portion of the heat exchanger.

4. A heat exchanger according to claim 2 wherein,

comprises one heat exchanger core, a 1 st header is arranged at the lower end part of the heat exchanger core, a 2 nd header is arranged at the upper end part of the heat exchanger core,

the hot gas refrigerant inlet is formed at one end of the 1 st header,

a liquid refrigerant outlet through which the refrigerant flows out when the heat exchanger functions as a condenser is formed at one end of the 2 nd header, which is located on the opposite side of the one end of the 1 st header.

5. A heat exchanger according to any one of claims 1 to 3 wherein,

the heat exchanger comprises a heat exchanger core, a 1 st header is arranged at the lower end part of the heat exchanger core, a 2 nd header is arranged at the upper end part of the heat exchanger core,

the heat exchanger includes a partition plate provided at least in the 1 st header to partition the flow path of the heat exchanger core into a plurality of regions in the width direction,

in defining the width of the heat exchanger core as Lm]The width of the region of the heat exchanger core at the most downstream side is defined as L ₁ In the case of (a) the number of the cells,

satisfy 20[%]≤L ₁ /L≤50[％]。

6. A heat exchanger according to claim 2 wherein,

the heat exchanger includes two or more heat exchanger cores along a flow direction of the air, a 1 st header provided at a lower end portion of the heat exchanger core located at a most windward side, a 2 nd header provided at an upper end portion or a lower end portion of the heat exchanger core located at a most windward side, the hot gas refrigerant inlet formed at one end of the 1 st header, a liquid refrigerant outlet formed at one end of the 2 nd header located at the same side as one end of the 1 st header for refrigerant outflow when the heat exchanger functions as a condenser,

The heat exchanger includes a cross-row header provided at an upper end or a lower end of two adjacent heat exchanger cores, and the cross-row header distributes the refrigerant merged from each of the flat tubes of the heat exchanger cores on a leeward side to each of the flat tubes of the heat exchanger cores on an upwind side.

7. The heat exchanger of claim 6, wherein the heat exchanger is configured to heat the heat exchanger,

the upper end or lower end of each of the flat tubes of the adjacent two heat exchanger cores is inserted into the cross-row header,

when a gap between an upper end portion or a lower end portion of the flat tube and a wall portion of the cross-row header opposing the upper end portion or the lower end portion is defined as δ,

meets delta less than or equal to 3 mm.

8. A heat exchanger according to any one of claims 1 to 3 wherein,

in the case where the width of the heat exchanger core is defined as Lm,

satisfies H/L > 1.

9. A heat exchanger according to any one of claims 1 to 3 wherein,

meets H not less than 0.42 m.

10. A heat exchanger according to any one of claims 1 to 9 wherein,

the flat tube is provided with a plurality of partition columns that partition the flow paths inside, and a convex portion that protrudes inward is provided between adjacent partition columns.

11. A heat exchanger according to any one of claims 1 to 9 wherein,

the front end portion of the flat tube is subjected to a tube shrinking process, whereby the outer diameter of the flat tube is reduced toward the front end.

12. A heat exchanger mounted in an outdoor unit of an air conditioner, the heat exchanger comprising one heat exchanger core or two or more heat exchanger cores extending in a direction of air flow, the heat exchanger core comprising a plurality of flat tubes extending in a vertical direction, wherein when the heat exchanger functions as a condenser, a refrigerant flows as an upward flow inside the flat tubes,

the heat exchanger is characterized in that,

the flow path cross-sectional area of each flat tube is defined as a [ m ] ² ]The number of the flat tubes flowing hot gas refrigerant as an upward flow in the heat exchanger is N _r [ root of Fabry-Perot ]]The total flow path cross-sectional area of the heat exchanger core in the upflow region at this time is defined as A _r [m ² ]＝a×N _r [m ² ]The height of the heat exchanger core is defined as Hm]The differential pressure of the refrigerant flow path is defined as Δp _HEX The liquid head is defined as ΔP _HEAD In the case of (1), satisfy ΔP _HEX /ΔP _HEAD ＝(5.94635×10 ^－4 ×A _r ^－1.75030 )/(8.4303H+0.8779)＞1。

13. An outdoor unit of an air conditioner, characterized in that,

A heat exchanger according to any one of claims 1 to 12.

14. An air conditioner is characterized by comprising:

the outdoor unit of the air conditioner of claim 13;

an indoor unit of an air conditioner; and

and a refrigerant circuit configured by an outdoor unit of the air conditioner and an indoor unit of the air conditioner, and configured to circulate a refrigerant.

15. An air conditioner according to claim 14, wherein,

the outdoor unit of the air conditioner is provided with a plurality of heat exchangers,

the air conditioner includes a control device configured to connect the flow of the refrigerant in some of the plurality of heat exchangers in series with the flow of the refrigerant in the other heat exchangers during defrosting operation, and configured to connect the flows of the refrigerant in the heat exchangers in parallel when the heat exchangers function as evaporators.

16. An air conditioner according to claim 15, wherein,

in the defrosting operation, the control device is configured to connect the flow of the refrigerant in a part of the heat exchangers to the flow of the refrigerant in the other heat exchangers in series, and connect the flows of the refrigerant in the other heat exchangers in parallel,

In the defrosting operation, when the plurality of heat exchangers are configured such that the flow of the refrigerant is parallel, the control device preferably performs the defrosting operation for the other heat exchangers without flowing the refrigerant into at least one of the heat exchangers.

17. An air conditioning unit according to any of claims 14 to 16, characterized in that,

the refrigerant is any one pure refrigerant of HFO1123, HFO1132 (E), R1234yf, R1234ze (E), R1234ze (Z), R1233zd (E), propane (R290) and fluoroethane (R161).