WO2013150795A1

WO2013150795A1 - Heat exchanger

Info

Publication number: WO2013150795A1
Application number: PCT/JP2013/002327
Authority: WO
Inventors: 正憲神藤; 好男織谷; 菊池　芳正; 泰弘笹井; 博治久保; 智嗣井上; 鉉永金; 宏和藤野
Original assignee: ダイキン工業株式会社
Priority date: 2012-04-05
Filing date: 2013-04-03
Publication date: 2013-10-10
Also published as: EP2857788A1; CN104246414A; JP5626254B2; ES2708210T3; US20150027672A1; EP2857788B1; EP2857788A4; CN104246414B; JP2013217528A

Abstract

A heat exchanger wherein the ends of flat pipes (31) are inserted into a header collecting pipe (70). When the heat exchanger functions as an evaporator, a refrigerant in a gas-liquid two-phase state flows upward in a partial space (71a) in the header collecting pipe (70). The effective cross-sectional area A of the partial space (71a) of the header collecting pipe (70) is set on the basis of the mass flow rate of the refrigerant flowing to the partial space (71a) in the header collecting pipe (70). This effective cross-sectional area A is the area when the projected area A₁, which is the area (projected on the plane orthogonal to the axial direction of the header collecting pipe (70)) of the portion of a flat pipe (31) positioned in the partial space (71a), is subtracted from the area A₀ of the cross section of the partial space (71a) orthogonal to the axial direction of the header colleting pipe (70).

Description

Heat exchanger

The present invention relates to a heat exchanger including a plurality of flat tubes and a header collecting tube connected to each flat tube.

Conventionally, a heat exchanger including a plurality of flat tubes and a header collecting tube connected to each flat tube is known.

Patent Documents

1 and 2 each disclose this type of heat exchanger. Specifically, in the heat exchangers of each of these patent documents, the header collecting pipes are installed one by one at the left end and the right end of the heat exchanger, and the first header collecting pipe is changed to the second header collecting pipe. A plurality of flat tubes are arranged over the entire area. And the heat exchanger of each of these patent documents heat-exchanges the refrigerant | coolant which flows the inside of a flat tube with the air which flows the outside of a flat tube.

The heat exchanger described in Patent Document 1 functions as a condenser. In this heat exchanger, the gas refrigerant flowing into the upper end portion of the first header collecting pipe is distributed to all flat tubes. The refrigerant flowing through each flat tube dissipates heat and condenses, and then flows into the second header collecting tube. Thereafter, the refrigerant flows out from the lower end of the second header collecting pipe to the outside of the heat exchanger.

The heat exchanger described in Patent Document 2 also functions as a condenser. In this heat exchanger, the refrigerant that has flowed into the upper end portion of the first header collecting pipe flows out from the lower end portion of the second header collecting pipe once and a half between the two header collecting pipes.

JP 2006-105545 A JP 2005-003223 A

Incidentally, it is conceivable to use a heat exchanger as described in the above patent document as an evaporator. When this heat exchanger functions as an evaporator, the gas-liquid two-phase refrigerant supplied to the heat exchanger flows into one header collecting pipe and then flows into a plurality of flat tubes. In that case, it is desirable to make the flow rate of the refrigerant flowing into each flat tube as uniform as possible. This is because if the flow rate of the refrigerant flowing into each flat tube is not uniform, the refrigerant will be in a gas single-phase state in the middle of the flat tube where the flow rate of the refrigerant is small, and the performance of the heat exchanger will not be fully exhibited. .

However, conventionally, the factors necessary for evenly distributing the refrigerant in the gas-liquid two-phase state from the header collecting pipe to the plurality of flat tubes have not been sufficiently investigated, so that it is sufficient for a heat exchanger functioning as an evaporator. It was difficult to achieve a satisfactory performance.

The present invention has been made in view of the above points, and its purpose is to maximize its performance when a heat exchanger provided with a plurality of flat tubes and header collecting tubes functions as an evaporator. There is to make it.

The first invention includes a plurality of flat tubes (31), a first header collecting tube (60) into which one end of each flat tube (31) is inserted, and the other of the flat tubes (31). The second header collecting pipe (70) into which the end of the pipe is inserted, and a plurality of fins (36) joined to the flat pipe (31), the heat provided in the refrigerant circuit (20) that performs the refrigeration cycle Intended for exchangers. The second header collecting pipe (70) communicates with the plurality of flat pipes (31), and when the heat exchanger functions as an evaporator, a flow space in which a gas-liquid two-phase refrigerant flows upward. (71a to 71c) and from the cross-sectional area of the flow space (71a to 71c) perpendicular to the axial direction of the second header collecting pipe (70), the flow space ( When the area obtained by subtracting the projected area on the plane perpendicular to the axial direction of the second header collecting pipe (70) of the portion located at 71a to 71c) is the effective sectional area of the distribution space (71a to 71c) In addition, the effective area of the circulation space (71a to 71c) is set based on the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) when the heat exchanger functions as an evaporator. Is.

The heat exchanger (23) of the first invention is provided in the refrigerant circuit (20) that performs the refrigeration cycle. In the heat exchanger (23), the second header collecting pipe (70) forms a circulation space (71a to 71c). The flow of the refrigerant when the heat exchanger (23) functions as an evaporator will be described. The gas-liquid two-phase refrigerant flows into the flow space (71a to 71c) of the second header collecting pipe (70). In the circulation space (71a to 71c), the refrigerant flowing in flows upward. The refrigerant flowing through the circulation spaces (71a to 71c) is divided into a plurality of flat tubes (31) communicating with the circulation spaces (71a to 71c). The refrigerant flowing into the flat tube (31) from the circulation space (71a to 71c) passes through the flat tube (31) and flows into the first header collecting tube (60).

In the first invention, the effective cross-sectional area A of the distribution space (71a to 71c) of the second header collecting pipe (70) is the distribution space (71a to 71c) orthogonal to the axial direction of the second header collecting pipe (70). from the area a ₀ of the cross section of) the projection area a ₁ in the axial direction perpendicular to the plane of circulation space of the flat tubes (31) (second header collecting pipe portion located 71a ~ 71c) (70) The area after subtraction (A = A ₀ -A ₁ ). In the heat exchanger (23) of the present invention, the effective area A of the circulation space (71a to 71c) of the second header collecting pipe (70) is the circulation space when the heat exchanger (23) functions as an evaporator. It is set based on the mass flow rate of the refrigerant flowing into (71a to 71c).

According to a second invention, in the first invention, when the heat exchanger functions as an evaporator, one value included in the fluctuation range of the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) is obtained. When the reference mass flow rate M _R [kg / h] is used, the effective area A [mm ² ] of the flow space (71a to 71c) is (1.91M _R −22.7) or more (1.96M _R ). +30.8) or less.

According to a third invention, in the first invention, when the heat exchanger functions as an evaporator, one value included in the fluctuation range of the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) is obtained. When the reference mass flow rate M _R [kg / h] is set, the effective area A [mm ² ] of the flow space (71a to 71c) is (1.96M _R −25.0) or more (1.96M _R +30.0) or less.

In each of the second and third inventions, the mass flow rate of the refrigerant flowing into the heat exchanger (23) functioning as an evaporator depends on the operating state of the refrigerant circuit (20) provided with the heat exchanger (23). Change. When the heat exchanger (23) functions as an evaporator, the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) varies within a predetermined range. One of the values contained in the variation range of the mass flow rate of the refrigerant, and a reference mass flow rate M _R. Reference mass flow rate M _R may be a maximum value and a minimum value of, for example, the variation range may be a central value of the fluctuation range. In each invention of the second and third, a unit of the reference mass flow rate M _R is "kg / h", the unit of effective area A is "mm ^2".

In the second invention, the effective area A of the flow space (71a to 71c) of the second header collecting pipe (70) is a value that satisfies the following mathematical formula.
1.91M _R −22.7 ≦ A ≦ 1.96M _R +30.8

On the other hand, in the third invention, the effective cross-sectional area A of the flow space (71a to 71c) of the second header collecting pipe (70) is a value that satisfies the following mathematical formula.
1.96M _R -25.0 ≦ A ≦ 1.96M _R +30.0

According to a fourth invention, in the second or third invention, the reference mass flow rate M _R [kg / h] is supplied to the circulation space (71a to 71c) when the heat exchanger functions as an evaporator. This is the maximum value of the fluctuation range of the mass flow rate of the refrigerant flowing in.

In the fourth invention, the maximum value of the variation range of the mass flow rate of refrigerant flowing into flow space (71a ~ 71c) when the heat exchanger (23) functions as an evaporator becomes a reference mass flow rate M _R.

According to a fifth invention, in any one of the first to fourth inventions, the first header collecting pipe (60) and the second header collecting pipe (70) are installed in an upright state, and the heat When the exchanger functions as an evaporator, the refrigerant is configured to flow into the lower end of the circulation space (71a to 71c).

In the fifth invention, the first header collecting pipe (60) and the second header collecting pipe (70) are erected. When the heat exchanger (23) of the present invention functions as an evaporator, the refrigerant flowing into the lower end of the flow space (71a to 71c) of the second header collecting pipe (70) flows upward.

Here, in the heat exchanger (23) functioning as an evaporator, the gas-liquid two-phase refrigerant flowing upward through the circulation spaces (71a to 71c) of the second header collecting pipe (70) is supplied to a plurality of flat tubes (31 ) To be distributed evenly, it is necessary to set the flow rate of the refrigerant in the distribution space (71a to 71c) to an appropriate value. This is a fact found out as a result of the inventors of the present invention examining the results of various experiments.

In other words, if the flow rate of the refrigerant flowing upward in the circulation space (71a to 71c) is too low, liquid refrigerant hardly reaches the upper flat tube (31), and therefore flows into the upper flat tube (31). The dryness of the refrigerant increases. For this reason, in the flat tube (31) communicating with the distribution space (71a to 71c), the heat exchanger (23) has sufficient performance because the amount of heat absorbed by the refrigerant flowing therethrough is reduced. Will not be demonstrated. If the flow rate of the refrigerant flowing upward in the circulation space (71a to 71c) is too high, most of the liquid refrigerant blown up vigorously flows into the upper flat tube (31), and the lower flat tube (31 ) Increases the dryness of the refrigerant flowing into the lower flat tube (31). For this reason, the flat pipe (31) that communicates with the distribution space (71a to 71c) placed at the lower side reduces the amount of heat absorbed by the refrigerant flowing through it, and the performance of the heat exchanger (23) is sufficient. Will not be demonstrated. As described above, the performance of the heat exchanger (23) is not sufficiently exhibited both when the flow rate of the refrigerant flowing upward in the circulation spaces (71a to 71c) is too low and too high.

Therefore, in the present invention, the effective cross-sectional area A of the flow space (71a to 71c) of the second header collecting pipe (70) is determined as the flow space (71a to 71c) when the heat exchanger (23) functions as an evaporator. It is set based on the mass flow rate of the refrigerant flowing in. The effective sectional area A of the circulation space (71a to 71c) and the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) are physical quantities that affect the flow velocity of the refrigerant flowing in the circulation space (71a to 71c). . Therefore, if the effective area A of the circulation space (71a to 71c) is set based on the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c), the flow rate of the refrigerant flowing through the circulation space (71a to 71c) It is possible to set an appropriate value such that the refrigerant is evenly distributed from the distribution space (71a to 71c) to the plurality of flat tubes (31). Therefore, according to this invention, it becomes possible to fully exhibit the performance of the heat exchanger (23) which functions as an evaporator.

Here, it is assumed that the heat absorption amount of the refrigerant in the heat exchanger (23) functioning as an evaporator is insufficient. At this time, if the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) is smaller than the maximum value of the fluctuation range, the refrigerant mass absorption is increased by increasing the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c). It is possible to increase the amount of heat. However, if the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) has already reached the maximum fluctuation range, the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) cannot be increased any further. .

In contrast, in the fourth invention, the reference mass flow rate M _R to be used for setting the effective area A of the flow space (71a ~ 71c), when the heat exchanger (23) functions as an evaporator The maximum value of the fluctuation range of the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c). Therefore, according to the present invention, when the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) cannot be increased, the performance of the heat exchanger (23) can be maximized.

FIG. 1 is a refrigerant circuit diagram illustrating a schematic configuration of an air conditioner including the outdoor heat exchanger according to the first embodiment. FIG. 2 is a front view illustrating a schematic configuration of the outdoor heat exchanger according to the first embodiment. FIG. 3 is a partial cross-sectional view illustrating the front of the outdoor heat exchanger according to the first embodiment. FIG. 4 is an enlarged cross-sectional view showing a part of the AA cross section of FIG. 5 is an enlarged cross-sectional view showing the main part of the BB cross section of FIG. 3, wherein (a) shows the dimensions of each part, and (b) shows the cross-sectional area of the partial space in the second header collecting pipe. shows the a _0, (c) shows a projected area a ₁ of the flat tube, (d) shows the effective area a of the subspaces of the second header set tube. FIG. 6 is a graph showing the relationship between the refrigerant flow velocity V in the partial space in the second header collecting pipe and the capacity ratio of the outdoor heat exchanger. FIG. 7 is a graph showing the range of the effective area A in the outdoor heat exchanger according to the first embodiment. FIG. 8 is a graph showing the range of the effective area A in the outdoor heat exchanger according to the second modification of the first embodiment.

Embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments and modifications described below are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

The heat exchanger of this embodiment is an outdoor heat exchanger (23) provided in the air conditioner (10). Below, an air conditioner (10) is demonstrated first, and the outdoor heat exchanger (23) is demonstrated in detail after that.

-Air conditioner-
First, the air conditioner (10) will be described with reference to FIG.

<Configuration of air conditioner>
The air conditioner (10) includes an outdoor unit (11) and an indoor unit (12). The outdoor unit (11) and the indoor unit (12) are connected to each other via a liquid side connecting pipe (13) and a gas side connecting pipe (14). In the air conditioner (10), the refrigerant circuit (20) is formed by the outdoor unit (11), the indoor unit (12), the liquid side communication pipe (13), and the gas side communication pipe (14).

The refrigerant circuit (20) is provided with a compressor (21), a four-way switching valve (22), an outdoor heat exchanger (23), an expansion valve (24), and an indoor heat exchanger (25). ing. The compressor (21), the four-way switching valve (22), the outdoor heat exchanger (23), and the expansion valve (24) are accommodated in the outdoor unit (11). The outdoor unit (11) is provided with an outdoor fan (15) for supplying outdoor air to the outdoor heat exchanger (23). On the other hand, the indoor heat exchanger (25) is accommodated in the indoor unit (12). The indoor unit (12) is provided with an indoor fan (16) for supplying room air to the indoor heat exchanger (25).

The refrigerant circuit (20) is a closed circuit filled with refrigerant. In the refrigerant circuit (20), the compressor (21) has its discharge side connected to the first port of the four-way switching valve (22) and its suction side connected to the second port of the four-way switching valve (22). Yes. In the refrigerant circuit (20), the outdoor heat exchanger (23), the expansion valve (24), and the indoor heat exchanger are sequentially arranged from the third port to the fourth port of the four-way switching valve (22). (25) and are arranged.

Compressor (21) is a scroll type or rotary type hermetic compressor. The compressor (21) has a variable rotational speed. When the rotational speed of the compressor (21) is changed, the operating capacity of the compressor (21) changes. The four-way switching valve (22) has a first state (state indicated by a broken line in FIG. 1) in which the first port communicates with the third port and the second port communicates with the fourth port, The port is switched to a second state (state indicated by a solid line in FIG. 1) in which the port communicates with the fourth port and the second port communicates with the third port. The expansion valve (24) is a so-called electronic expansion valve.

The outdoor heat exchanger (23) exchanges heat between the outdoor air and the refrigerant. The outdoor heat exchanger (23) will be described later. On the other hand, the indoor heat exchanger (25) exchanges heat between the indoor air and the refrigerant. The indoor heat exchanger (25) is constituted by a so-called cross fin type fin-and-tube heat exchanger provided with a heat transfer tube which is a circular tube.

<Operation of air conditioner>
The air conditioner (10) selectively performs a cooling operation and a heating operation.

In the refrigerant circuit (20) during the cooling operation, the refrigeration cycle is performed with the four-way switching valve (22) set to the first state. In this state, the refrigerant circulates in the order of the outdoor heat exchanger (23), the expansion valve (24), and the indoor heat exchanger (25), and the outdoor heat exchanger (23) functions as a condenser. (25) functions as an evaporator. In the outdoor heat exchanger (23), the gas refrigerant flowing from the compressor (21) dissipates heat to the outdoor air and condenses, and the condensed refrigerant flows out toward the expansion valve (24).

In the refrigerant circuit (20) during the heating operation, the refrigeration cycle is performed with the four-way switching valve (22) set to the second state. In this state, the refrigerant circulates in the order of the indoor heat exchanger (25), the expansion valve (24), and the outdoor heat exchanger (23), and the indoor heat exchanger (25) functions as a condenser. (23) functions as an evaporator. The refrigerant that has expanded into the gas-liquid two-phase state flows into the outdoor heat exchanger (23) when passing through the expansion valve (24). The refrigerant that has flowed into the outdoor heat exchanger (23) absorbs heat from the outdoor air and evaporates, and then flows out toward the compressor (21).

-Outdoor heat exchanger-
The outdoor heat exchanger (23) will be described with reference to FIGS. Note that the number of flat tubes (31, 32) and the number of main heat exchange units (51a to 51c) and auxiliary heat exchange units (52a to 52c) shown in the following description are merely examples.

<Configuration of outdoor heat exchanger>
As shown in FIGS. 2 and 3, the outdoor heat exchanger (23) includes one first header collecting pipe (60), one second header collecting pipe (70), and many flat tubes (31, 31). 32) and a large number of fins (36). The first header collecting pipe (60), the second header collecting pipe (70), the flat pipe (31, 32) and the fin (35) are all made of an aluminum alloy and are joined to each other by brazing. Yes.

As will be described in detail later, the outdoor heat exchanger (23) is divided into a main heat exchange region (51) and an auxiliary heat exchange region (52). In this outdoor heat exchanger (23), some flat tubes (32) constitute an auxiliary heat exchange region (52), and the remaining flat tubes (31) constitute a main heat exchange region (51). .

The first header collecting pipe (60) and the second header collecting pipe (70) are both formed in an elongated cylindrical shape whose both ends are closed. 2 and 3, the first header collecting pipe (60) stood up at the left end of the outdoor heat exchanger (23), and the second header collecting pipe (70) stood up at the right end of the outdoor heat exchanger (23). It is installed in a state. That is, the first header collecting pipe (60) and the second header collecting pipe (70) are installed in a state where the respective axial directions are in the vertical direction.

As shown in FIG. 4, the flat tubes (31, 32) are heat transfer tubes whose cross-sectional shape is a flat oval. As shown in FIG. 3, in the outdoor heat exchanger (23), the plurality of flat tubes (31, 32) are arranged in a state in which the extending direction is the left-right direction and the flat side surfaces face each other. In addition, the plurality of flat tubes (31, 32) are arranged side by side at regular intervals and are substantially parallel to each other. Each flat tube (31, 32) has one end inserted into the first header collecting tube (60) and the other end inserted into the second header collecting tube (70). The axial direction of each flat tube (31, 32) is substantially orthogonal to the axial direction of each header collecting tube (60, 70). Further, the flat side surfaces (upper and lower side surfaces in this embodiment) of each flat tube (31, 32) are substantially orthogonal to the axial direction of each header collecting tube (60, 70).

As shown in FIG. 4, a plurality of fluid passages (34) are formed in each flat tube (31, 32). Each fluid passage (34) is a passage extending in the extending direction of the flat tube (31, 32). In each flat tube (31, 32), the plurality of fluid passages (34) are arranged in a line in the width direction of the flat tube (31, 32) (that is, the direction orthogonal to the longitudinal direction). One end of each of the plurality of fluid passages (34) formed in each flat tube (31, 32) communicates with the internal space of the first header collecting pipe (60), and the other end of each fluid passage (34) is the second header collecting pipe. It communicates with the internal space of (70). The refrigerant supplied to the outdoor heat exchanger (23) exchanges heat with air while flowing through the fluid passage (34) of the flat tubes (31, 32).

As shown in FIG. 4, the fin (36) is a vertically long plate-like fin formed by pressing a metal plate. The fin (36) is formed with a number of elongated notches (45) extending in the width direction of the fin (36) from the front edge of the fin (36) (that is, the windward edge). In the fin (36), a large number of notches (45) are formed at regular intervals in the longitudinal direction (vertical direction) of the fin (36). The portion closer to the lee of the notch (45) constitutes the tube insertion portion (46). The tube insertion portion (46) has a vertical width substantially equal to the thickness of the flat tube (31, 32) and a length substantially equal to the width of the flat tube (31, 32). The flat tubes (31, 32) are inserted into the tube insertion portion (46) of the fin (36) and joined to the peripheral portion of the tube insertion portion (46) by brazing. Moreover, the louver (40) for promoting heat transfer is formed in the fin (36). The plurality of fins (36) are arranged in the extending direction of the flat tubes (31, 32) so that the air flows between the adjacent flat tubes (31, 32) into the plurality of ventilation paths (38). It is partitioned.

As shown in FIGS. 2 and 3, the outdoor heat exchanger (23) is divided into two heat exchange regions (51, 52) in the vertical direction. In the outdoor heat exchanger (23), the upper heat exchange region is the main heat exchange region (51), and the lower heat exchange region is the auxiliary heat exchange region (52).

各 Each heat exchange area (51, 52) is divided into three heat exchange sections (51a to 51c, 52a to 52c). That is, in the outdoor heat exchanger (23), each of the main heat exchange region (51) and the auxiliary heat exchange region (52) is divided into a plurality of heat exchange portions (51a to 51c, 52a to 52c). ing. The number of heat exchanging portions (51a to 51c, 52a to 52c) formed in each heat exchanging region (51, 52) may be two, or four or more.

Specifically, in the main heat exchange region (51), the first main heat exchange unit (51a), the second main heat exchange unit (51b), and the third main heat exchange unit are sequentially arranged from the bottom to the top. (51c) is formed. In the auxiliary heat exchange region (52), in order from bottom to top, a first auxiliary heat exchange unit (52a), a second auxiliary heat exchange unit (52b), and a third auxiliary heat exchange unit (52c) Is formed. Each main heat exchange section (51a to 51c) and each auxiliary heat exchange section (52a to 52c) are provided with a plurality of flat tubes (31, 32). Further, as shown in FIG. 3, the number of flat tubes (31) constituting each main heat exchange section (51a to 51c) is equal to the number of flat tubes (32) constituting each auxiliary heat exchange section (52a to 52c). More than the number. Therefore, the number of flat tubes (31) constituting the main heat exchange region (51) is larger than the number of flat tubes (32) constituting the auxiliary heat exchange region (52).

As shown in FIG. 3, the internal space of the first header collecting pipe (60) is vertically divided by a partition plate (39a). In the first header collecting pipe (60), the space above the partition plate (39a) is the upper space (61), and the space below the partition plate (39a) is the lower space (62).

The upper space (61) constitutes a main communication space corresponding to the main heat exchange area (51). The upper space (61) is a single space communicating with all of the flat tubes (31) constituting the main heat exchange region (51). That is, the upper space (61) communicates with the flat tube (31) of each main heat exchange section (51a to 51c).

The lower space (62) constitutes an auxiliary communication space corresponding to the auxiliary heat exchange region (52). The lower space (62) is partitioned up and down by two partition plates (39b). Specifically, the lower space (62) is partitioned into the same number (three in this embodiment) of communication chambers (62a to 62c) as the auxiliary heat exchange sections (52a to 52c). The lowermost first communication chamber (62a) communicates with all the flat tubes (32) constituting the first auxiliary heat exchange section (52a). The second communication chamber (62b) located above the first communication chamber (62a) communicates with all the flat tubes (32) constituting the second auxiliary heat exchange section (52b). The uppermost third communication chamber (62c) communicates with all the flat tubes (32) constituting the third auxiliary heat exchange section (52c).

The internal space of the second header collecting pipe (70) is divided into a main communication space (71) corresponding to the main heat exchange area (51) and an auxiliary communication space (72) corresponding to the auxiliary heat exchange area (52). Has been.

The main communication space (71) is divided up and down by two partition plates (39c). The partition plate (39c) divides the main communication space (71) into the same number (three in this embodiment) of partial spaces (71a to 71c) as the main heat exchange portions (51a to 51c). The lowermost first partial space (71a) communicates with all the flat tubes (31) constituting the first main heat exchange section (51a). The second partial space (71b) located above the first partial space (71a) communicates with all the flat tubes (31) constituting the second main heat exchange section (51b). The uppermost third partial space (71c) communicates with all the flat tubes (31) constituting the third main heat exchange section (51c). Each partial space (71a to 71c) is a circulation space in which the refrigerant flows upward when the outdoor heat exchanger (23) functions as an evaporator.

The auxiliary communication space (72) is vertically divided by two partition plates (39d). The partition plate (39d) divides the auxiliary communication space (72) into the same number (three in this embodiment) of partial spaces (72a to 72c) as the auxiliary heat exchange parts (52a to 52c). The lowermost fourth partial space (72a) communicates with all the flat tubes (32) constituting the first auxiliary heat exchange section (52a). The fifth partial space (72b) located above the fourth partial space (72a) communicates with all the flat tubes (32) constituting the second auxiliary heat exchange section (52b). The sixth partial space (72c) located at the uppermost position communicates with all the flat tubes (32) constituting the third auxiliary heat exchange section (52c).

Two pipes for connection (76, 77) are attached to the second header collecting pipe (70). These connection pipes (76, 77) are all circular pipes.

The first connection pipe (76) has one end connected to the second partial space (71b) corresponding to the second main heat exchange part (51b) and the other end corresponding to the first auxiliary heat exchange part (52a). Connected to the fourth partial space (72a). The second connection pipe (77) has one end connected to the third partial space (71c) corresponding to the third main heat exchange part (51c) and the other end corresponding to the second auxiliary heat exchange part (52b). Connected to the fifth partial space (72b). Further, in the second header collecting pipe (70), a sixth partial space (72c) corresponding to the third auxiliary heat exchange section (52c) and a first partial space corresponding to the first main heat exchange section (51a) ( 71a) form one continuous space.

Thus, in the outdoor heat exchanger (23) of this embodiment, the 1st main heat exchange part (51a) and the 3rd auxiliary heat exchange part (52c) are connected in series, and the 2nd main heat exchange part (51b ) And the first auxiliary heat exchanger (52a) are connected in series, and the third main heat exchanger (51c) and the second auxiliary heat exchanger (52b) are connected in series.

As shown in FIG. 2, the outdoor heat exchanger (23) is provided with a liquid side connection member (80) and a gas side connection pipe (85). The liquid side connection member (80) and the gas side connection pipe (85) are attached to the first header collecting pipe (60).

The liquid side connection member (80) includes one shunt (81) and three small diameter tubes (82a to 82c). A pipe (17) connecting the outdoor heat exchanger (23) and the expansion valve (24) is connected to the lower end of the flow divider (81). One end of each small diameter pipe (82a to 82c) is connected to the upper end of the flow divider (81). Inside the flow divider (81), the pipe connected to the lower end portion thereof communicates with the small diameter pipes (82a to 82c). The other end of each small-diameter pipe (82a to 82c) is connected to the first header collecting pipe (60) and communicates with the corresponding lower partial space (62a to 62c).

As shown also in FIG. 3, each small-diameter pipe (82a to 82c) has a portion near the lower end of the corresponding lower partial space (62a to 62c) (ie, the vertical direction of the lower partial space (62a to 62c)). (The part below the center). That is, the first small-diameter pipe (82a) opens at a portion near the lower end of the first lower partial space (62a), and the second small-diameter pipe (82b) is near the lower end of the second lower partial space (62b). The third small-diameter pipe (82c) opens in a portion near the lower end of the third lower partial space (62c). The lengths of the small diameter tubes (82a to 82c) are individually set so that the difference in the flow rate of the refrigerant flowing into the heat exchange sections (50a to 50c) is as small as possible.

One end of the gas side connection pipe (57) is connected to the upper part of the first header collecting pipe (60) and communicates with the upper space (61). The other end of the gas side connection pipe (57) is connected to a pipe (18) connecting the outdoor heat exchanger (23) and the third port of the four-way switching valve (22).

<Refrigerant flow in outdoor heat exchanger / condenser>
During the cooling operation of the air conditioner (10), the outdoor heat exchanger (23) functions as a condenser. The flow of the refrigerant in the outdoor heat exchanger (23) during the cooling operation will be described.

The gas refrigerant discharged from the compressor (21) is supplied to the outdoor heat exchanger (23). The gas refrigerant sent from the compressor (21) flows into the upper space (61) of the first header collecting pipe (60) via the gas side connection pipe (57), and then flows into the main heat exchange region (51). It is distributed to each flat tube (31). In each main heat exchange section (51a to 51c) of the main heat exchange area (51), the refrigerant flowing into the fluid passage (34) of the flat tube (31) dissipates heat to the outdoor air while flowing through the fluid passage (34). Then, it condenses and then flows into the corresponding partial spaces (71a to 71c) of the second header collecting pipe (70).

The refrigerant that has flowed into the partial spaces (71a to 71c) of the main communication space (71) is sent to the corresponding partial spaces (72a to 72c) of the auxiliary communication space (72). Specifically, the refrigerant flowing into the first partial space (71a) of the main communication space (71) flows down and flows into the sixth partial space (72c) of the auxiliary communication space (72). The refrigerant flowing into the second partial space (71b) of the main communication space (71) flows into the fourth partial space (72a) of the auxiliary communication space (72) through the first connection pipe (76). The refrigerant that has flowed into the third partial space (71c) of the main communication space (71) flows into the fifth partial space (72b) of the auxiliary communication space (72) through the second connection pipe (77).

The refrigerant that has flowed into the partial spaces (72a to 72c) of the auxiliary communication space (72) is distributed to the flat tubes (32) of the corresponding auxiliary heat exchange sections (52a to 52c). The refrigerant flowing through the fluid passage (34) of each flat tube (32) dissipates heat to the outdoor air and becomes supercooled liquid, and then the corresponding communication chamber in the lower space (62) of the first header collecting pipe (60). Flows into (62a-62c). The refrigerant in each communication chamber (62a to 62c) flows into the flow divider (81) through the narrow pipes (82a to 82c), joins, and flows out from the outdoor heat exchanger (23).

<Flow of refrigerant in outdoor heat exchanger / Evaporator>
During the heating operation of the air conditioner (10), the outdoor heat exchanger (23) functions as an evaporator. The flow of the refrigerant in the outdoor heat exchanger (23) during the heating operation will be described.

The outdoor heat exchanger (23) is supplied with a refrigerant that has expanded into a gas-liquid two-phase state when passing through the expansion valve (24). The refrigerant sent from the expansion valve (24) flows into the flow divider (81) of the liquid side connection member (80) and then into the three small diameter tubes (82a to 82c). (50a-50c).

Specifically, the refrigerant that has flowed from the flow divider (81) into the small diameter pipes (82a to 82c) flows into the communication chambers (62a to 62c) of the corresponding first header collecting pipe (60). The refrigerant that has flowed into the communication chambers (62a to 62c) of the first header collecting pipe (60) is distributed to the flat tubes (32) of the corresponding auxiliary heat exchange sections (52a to 52c). The refrigerant flowing into the fluid passage (34) of each flat tube (32) absorbs heat from the outdoor air while flowing through the fluid passage (34), and a part of the liquid refrigerant evaporates. The refrigerant that has passed through the fluid passage (34) of the flat tube (32) flows into the corresponding partial spaces (72a to 72c) of the auxiliary communication space (72) of the second header collecting pipe (70). The refrigerant that has flowed into the partial spaces (72a to 72c) still remains in a gas-liquid two-phase state.

The refrigerant that has flowed into the partial spaces (72a to 72c) of the auxiliary communication space (72) is sent to the corresponding partial spaces (71a to 71c) of the main communication space (71). Specifically, the refrigerant that has flowed into the fourth partial space (72a) of the auxiliary communication space (72) passes through the first connection pipe (76) and flows into the second partial space (71b) of the main communication space (71). It flows into the lower end. The refrigerant flowing into the fifth partial space (72b) of the auxiliary communication space (72) flows into the lower end of the third partial space (71c) of the main communication space (71) through the second connection pipe (77). To do. The refrigerant flowing into the sixth partial space (72c) of the auxiliary communication space (72) flows upward and flows into the lower end portion of the first partial space (71a) of the main communication space (71).

In each partial space (71a to 71c) of the main communication space (71), the refrigerant flowing in flows upward. The refrigerant in each partial space (71a to 71c) is distributed to each flat tube (31) of the corresponding main heat exchange section (51a to 51c). The refrigerant flowing through the fluid passageway (34) of each flat tube (31) absorbs heat from the outdoor air and evaporates to substantially become a gas single-phase state, and then the upper space of the first header collecting pipe (60) ( 61). Thereafter, the refrigerant flows out of the outdoor heat exchanger (23) through the gas side connection pipe (57).

<Insertion length L of flat tube>
In the outdoor heat exchanger (23) of the present embodiment, the insertion length L of the flat tube (31) to the second header collecting pipe (70) is the main communication space formed in the second header collecting pipe (70). The effective area A of each partial space (71a to 71c) of (71) is set to a predetermined design value. The unit of the insertion length L is “mm”, and the unit of the effective area A is “mm ² ”. Further, in FIG. 5, illustration of the fin (36) is omitted.

As shown in FIG. 5 (a), the insertion length L of the flat tube (31) into the second header collecting tube (70) is the portion of the flat tube (31) inserted into the partial spaces (71a to 71c). Is the length of That is, the insertion length L is the distance from the end surface of the portion inserted into the partial space (71a to 71c) of the flat tube (31) to the inner surface of the second header collecting tube (70).

The effective cross-sectional area A of the partial space (71a to 71c) is the area of the region marked with dots in FIG. This effective cross-sectional area A is an area obtained by subtracting the projected area A ₁ of the flat tube (31) from the cross-sectional area A ₀ of the partial space (71a to 71c) (A = A ₀ −A ₁ ). Sectional area A ₀ of the subspace (71a ~ 71c) is the area of the region marked with dots in FIG. 5 (b). That is, the sectional area A ₀ of the partial spaces (71a to 71c) is the area of the cross section of the partial space (71a to 71c) orthogonal to the axial direction of the second header collecting pipe (70). The partial space (71a to 71c) has a circular cross section. Accordingly, the sectional area A ₀ of the partial spaces (71a to 71c) is (π / 4) d ² . Projected area A ₁ of the flat tube (31) is an area of the region marked with dots in FIG. 5 (c). That is, the projected area A ₁ of the flat tube (31), the portion located subspace (71a ~ 71c) of the flat tubes (31), onto a plane perpendicular to the axial direction of the second header collecting pipe (70) Is the projected area.

Here, the width W of the flat tube (31) is selected according to the design value of the capacity of the outdoor heat exchanger (23). Further, the inner diameter d of the second header collecting pipe (70) is set to a value such that a flat pipe (31) having a width W can be inserted. Thus, when designing the outdoor heat exchanger (23), the width W of the flat tube (31) and the inner diameter d of the second header collecting pipe (70) are determined first, and then the partial space The insertion length L of the flat tube (31) is determined so that the effective area A of (71a to 71c) becomes a predetermined value.

As described above, the operating capacity of the compressor (21) of the air conditioner (10) is variable. When the operating capacity of the compressor (21) changes, the amount of refrigerant circulating in the refrigerant circuit (20) changes, and the mass flow rate of refrigerant flowing into the outdoor heat exchanger (23) changes. In the air conditioner (10) during heating operation, the amount of refrigerant circulating in the refrigerant circuit (20) (that is, the mass flow rate of refrigerant flowing into the outdoor heat exchanger (23)) is approximately 90 kg / h or more and 270 kg / h. It fluctuates within the following range. On the other hand, the outdoor heat exchanger (23) is formed with three main heat exchange portions (51a to 51c), and the main communication space (71) in the second header collecting pipe (70) is divided into three partial spaces (71a ~ 71c). Therefore, in the outdoor heat exchanger (23) functioning as an evaporator, the mass flow rate of the refrigerant flowing into each partial space (71a to 71c) of the main communication space (71) in the second header collecting pipe (70) is In general, it fluctuates within the range of 30 kg / h to 90 kg / h.

In the outdoor heat exchanger (23) of the present embodiment, the maximum value (that is, 90 kg / h) of the fluctuation range of the mass flow rate of the refrigerant flowing into the partial spaces (71a to 71c) of the main communication space (71) is It has become a reference mass flow rate M _R. On the other hand, in the outdoor heat exchanger (23) of the present embodiment, the effective sectional area A of each partial space (71a to 71c) of the main communication space (71) is (1.91M _R -22.7) or more (1. and has a 96M _R +30.8) below. Accordingly, the outdoor heat exchanger (23), the effective area A of each subspace of the main communication space (71) (71a ~ 71c) is such that the 149 mm ² or more 207 mm ² or less, the second header collecting pipe ( 70), the insertion length L of the flat tube (31) is set.

In the outdoor heat exchanger (23) of the present embodiment, the second header collecting pipe (70) is set so that the effective sectional area A of each partial space (71a to 71c) of the main communication space (71) is 188 mm ^2. It is most desirable to set the insertion length L of the flat tube (31) with respect to (). For example, when the width W of the flat pipe (31) is 18 mm and the inner diameter d of the second header collecting pipe (70) is 21 mm, the effective disconnection of each partial space (71a to 71c) of the main communication space (71) In order to set the area A to 188 mm ² , the insertion length L of the flat tube (31) with respect to the second header collecting tube (70) may be set to 10 mm.

<Effective cross-sectional area A of the subspace of the main communication space>
As described above, in the outdoor heat exchanger (23) of the present embodiment, the insertion length L of the flat tube (31) with respect to the second header collecting pipe (70) is the main communication of the second header collecting pipe (70). The effective area A of each partial space (71a to 71c) of the space (71) is set to a predetermined design value.

In this outdoor heat exchanger (23), the effective cross-sectional area A [mm ² ] of each partial space (71a to 71c) of the main communication space (71) is (1.91M _R -22.7) or more (1. and has a 96M _R +30.8) below. The reference mass flow rate M _R [kg / h] is the mass of the refrigerant flowing into each partial space (71a to 71c) of the main communication space (71) when the outdoor heat exchanger (23) functions as an evaporator. It is an arbitrary value within the flow rate fluctuation range. If the effective area A of each partial space (71a to 71c) of the main communication space (71) is a value within the above range, each partial space (71a to 71c) of the main communication space (71). mass flow rate of refrigerant flowing into is at a reference mass flow rate M _R, the performance of the outdoor heat exchanger (23) functioning as an evaporator can be sufficiently exhibited. Here, the reason will be described with reference to FIGS.

FIG. 6 shows the main communication space (71) of the second header collecting pipe (70) for each of the heating low temperature condition, the heating rated condition, and the heating intermediate condition, which are the operating conditions of the heating operation of the air conditioner (10). When the effective area A of each partial space (71a to 71c) is changed, the flow rate V of the refrigerant in the partial space (71a to 71c) and the capacity ratio of the outdoor heat exchanger (23) functioning as an evaporator Shows the relationship. In the experiment for obtaining FIG. 6, the flat tube (31) has a width W of 18 mm, the second header collecting pipe (70) has a circular cross section, and the inner diameter of the second header collecting pipe (70). The target was an outdoor heat exchanger (23) in which d is 21 mm, and R410A was used as a refrigerant. In addition, the experiment for obtaining FIG. 6 was conducted on a plurality of types of heat exchangers in which only the effective cross-sectional area A of each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70) is different. It was performed using.

The heating low temperature condition is that the evaporating temperature Te of the refrigerant in the outdoor heat exchanger (23) is −7 ° C., and to each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70). This is an operating condition in which the mass flow rate M of the refrigerant flowing in is 90 kg / h. The rated heating condition is that the refrigerant evaporating temperature Te in the outdoor heat exchanger (23) is 0 ° C., and flows into each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70). This is an operating condition in which the mass flow rate M of the refrigerant is 80 kg / h. The heating intermediate condition is that the refrigerant evaporating temperature Te in the outdoor heat exchanger (23) is 2 ° C. and flows into each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70). This is an operating condition in which the mass flow rate M of the refrigerant is 40 kg / h.

The horizontal axis in FIG. 6 represents the refrigerant flow velocity V [m / s] in each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70). This flow velocity V is obtained by dividing the volume flow rate X [m ³ / s] of the refrigerant flowing into each partial space (71a to 71c) by the effective sectional area A [m ² ] of each partial space (71a to 71c). (V = X / A). Further, the volume flow rate X [m ³ / s] of the refrigerant flowing into each partial space (71a to 71c) is the mass flow rate M [kg / h] of the refrigerant flowing into each partial space (71a to 71c). It is calculated by dividing by the density D [kg / m ³ ] of the refrigerant flowing into the partial spaces (71a to 71c) (X = (M / 3600) / D).

6 represents the capacity ratio R of the outdoor heat exchanger (23) under each operating condition. The capacity ratio R is a percentage of the capacity ratio of the outdoor heat exchanger (23) of each specification with respect to a predetermined standard capacity. The standard capacity of the outdoor heat exchanger (23) is the capacity of the outdoor heat exchanger (23) when the effective sectional area A of the partial spaces (71a to 71c) is 188 mm ² .

Capacity ratio R of the outdoor heat exchanger (23) in the heating low temperature conditions, the ability Q ₁ in the heating low temperature condition of the outdoor heat exchanger (23) of each specification, the effective area A of the subspaces (71a ~ 71c) are It is calculated by dividing by the capacity of the outdoor heat exchanger (23) that is 188 mm ² under the heating low temperature condition (that is, the reference capacity Q _{01 under the} heating low temperature condition) (R = 100 (Q ₁ / Q ₀₁ )). Capacity ratio R of the outdoor heat exchanger (23) in the heating rated conditions, the ability Q ₂ in the heating rated conditions of the outdoor heat exchanger (23) of each specification, the effective area A of the subspaces (71a ~ 71c) are It is calculated by dividing by the capacity of the outdoor heat exchanger (23) that is 188 mm ² under the heating rated condition (that is, the reference capacity Q _{02 under the} heating rated condition) (R = 100 (Q ₂ / Q ₀₂ )). Capacity ratio R of the outdoor heat exchanger (23) in the heating intermediate condition, the capacity Q ₃ in the heating intermediate condition of the outdoor heat exchanger (23) of each specification, the effective area A of the subspaces (71a ~ 71c) are It is calculated by dividing by the capacity of the outdoor heat exchanger (23) that is 188 mm ² in the heating intermediate condition (that is, the reference capacity Q ₀₃ in the heating intermediate condition) (R = 100 (Q ₃ / Q ₀₃ )). Naturally, the reference capacities in the heating low temperature condition, the heating rated condition, and the heating intermediate condition are different from each other (Q ₀₁ ≠ Q ₀₂ ≠ Q ₀₃ ).

The capacity Q of the outdoor heat exchanger (23) is calculated by the formula: Q = G (h _out −h _in ). Where G is the mass flow rate of the refrigerant passing through the outdoor heat exchanger (23), h _in is the specific enthalpy of the refrigerant at the inlet of the outdoor heat exchanger (23), and h _out is the outdoor heat exchanger (23 ) Is the specific enthalpy of the refrigerant at the outlet.

The capacity of the outdoor heat exchanger (23) under heating and low temperature conditions is such that the effective sectional area A of each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70) is 152 mm ² , 188 mm ^2. , 214 mm ² , 240 mm ² of four types of outdoor heat exchangers (23). As a result, as shown in FIG. 6, the capacity of the outdoor heat exchanger (23) was maximized when the effective sectional area A of each partial space (71a to 71c) was 188 mm ² .

An outdoor heat exchanger in the heating rated conditions the ability of (23), the effective area A of each subspace of the main communication space of the second header collecting pipe (70) (71) (71a ~ 71c) is 117 mm ^2, 152 mm ² , was measured for 188 mm ^2, 214 mm ² 4 kinds of the outdoor heat exchanger (23). As a result, as shown in FIG. 6, the capacity of the outdoor heat exchanger (23) was maximized when the effective sectional area A of each partial space (71a to 71c) was 152 mm ² .

The capacity of the outdoor heat exchanger (23) in the intermediate heating condition is that the effective sectional area A of each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70) is 54 mm ² and 79 mm ^2. were measured for ^{^{^{117mm 2, 152mm 2, 188mm 2}}} , 214mm 2 six kinds of the outdoor heat exchanger (23). As a result, as shown in FIG. 6, when the effective cross-sectional area A of each partial space (71a to 71c) was 79 mm ² , the capacity of the outdoor heat exchanger (23) was maximized.

Thus, in each of the heating low temperature condition, the heating rated condition, and the heating intermediate condition, there is an effective sectional area A of the partial space (71a to 71c) in which the capacity of the outdoor heat exchanger (23) is maximized. The reason is as follows.

If the mass flow rate M of the refrigerant flowing into the partial spaces (71a to 71c) is constant, the flow velocity V of the refrigerant in the partial spaces (71a to 71c) increases as the effective sectional area A of the partial spaces (71a to 71c) increases. Lower. On the other hand, in each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70), the gas-liquid two-phase refrigerant flows upward. For this reason, when the flow velocity V of the refrigerant in the partial spaces (71a to 71c) decreases, a large amount of liquid refrigerant flows into the lower flat tube (31), and a low density gas refrigerant flows into the upper flat tube (31). A large amount flows into 31). That is, the mass flow rate of the refrigerant flowing into the flat tubes (31) from the partial spaces (71a to 71c) becomes uneven.

In the upper flat pipe (31) with a small amount of liquid refrigerant flowing in, the refrigerant enters a single-phase state before reaching the first header collecting pipe (60), and the temperature of the refrigerant approaches the temperature of the outdoor air. . As a result, the amount of heat exchange between the refrigerant and air in the upper portion of each main heat exchange section (51a to 51c) decreases, and the capacity of the outdoor heat exchanger (23) decreases.

In addition, if the mass flow rate M of the refrigerant flowing into the partial spaces (71a to 71c) is constant, the refrigerant flow velocity in the partial spaces (71a to 71c) decreases as the effective cross-sectional area A of the partial spaces (71a to 71c) decreases. V increases. As the flow velocity V of the refrigerant in the partial spaces (71a to 71c) increases, the inertial force acting on the liquid refrigerant having a high density increases. On the other hand, in each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70), the gas-liquid two-phase refrigerant flows upward. For this reason, in the partial spaces (71a to 71c), a large amount of liquid refrigerant blown up vigorously flows into the upper flat tube (31), and low density gas refrigerant flows into the lower flat tube (31). To do. That is, the mass flow rate of the refrigerant flowing into the flat tubes (31) from the partial spaces (71a to 71c) becomes uneven.

In the lower flat pipe (31) with a small amount of liquid refrigerant flowing in, the refrigerant enters a single-phase state before reaching the first header collecting pipe (60), and the temperature of the refrigerant approaches the temperature of the outdoor air. . As a result, the amount of heat exchange between the refrigerant and air in the lower portion of each main heat exchange section (51a to 51c) is reduced, and the capacity of the outdoor heat exchanger (23) is reduced.

Thus, in the outdoor heat exchanger (23), the flow velocity V of the refrigerant in each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70) is too high or too low. However, the distribution amount of the refrigerant to the flat tubes (31) communicating with the partial spaces (71a to 71c) becomes uneven, and as a result, the capacity of the outdoor heat exchanger (23) decreases. On the other hand, if the volume flow rate of the refrigerant flowing into the partial spaces (71a to 71c) is constant, the refrigerant flow velocity V in the partial spaces (71a to 71c) is proportional to the effective area A of the partial spaces (71a to 71c). To do. Therefore, as described above, there is an effective sectional area A of the partial space (71a to 71c) in which the capacity of the outdoor heat exchanger (23) is maximized in each of the heating low temperature condition, the heating rated condition, and the heating intermediate condition. To do.

FIG. 7 shows the experimental results shown in FIG. 6 with the mass flow rate M of the refrigerant flowing into the partial spaces (71a to 71c) of the main communication space (71) of the second header collecting pipe (70) and the partial spaces ( 71a to 71c) are rearranged into the relationship with the effective area A.

The point at which the capacity of the outdoor heat exchanger (23) is maximized in each of the heating low temperature condition, the heating rated condition, and the heating intermediate condition (that is, M = 40 kg / h and A = 79 mm ² , M = 80 kg / h) The primary approximate expression of the point of A = 152 mm ^{2 and} the point of M = 90 kg / h and A = 188 mm ² is the following expression 1.
(Formula 1) A = 1.96M

In addition, among the points where the capacity of the outdoor heat exchanger (23) is 95% of the maximum value in each of the heating low temperature condition, the heating rated condition, and the heating intermediate condition, the value in which the effective area A is calculated by Equation 1 The higher order (ie, the point M = 40 kg / h and A = 109 mm ² , the point M = 80 kg / h and A = 187 mm ² , and the point M = 90 kg / h and A = 207 mm ² ) The equation becomes the following equation 2.
(Formula 2) A = 1.96M + 30.8

In addition, among the points where the capacity of the outdoor heat exchanger (23) is 95% of the maximum value in each of the heating low temperature condition, the heating rated condition, and the heating intermediate condition, the value in which the effective area A is calculated by Equation 1 The first order approximation of the smaller one (ie, point M = 40 kg / h and A = 53 mm ² , point M = 80 kg / h and A = 130 mm ² , and point M = 90 kg / h and A = 149 mm ² ) The equation becomes the following equation 3.
(Formula 3) A = 1.91M-22.7

Therefore, in the outdoor heat exchanger (23) of this embodiment, the effective disconnection of each partial space (71a to 71c) is adjusted by adjusting the insertion length L of the flat tube (31) with respect to the second header collecting pipe (70). if the area a (1.91M _R -22.7) above (1.96M _R +30.8) below, the mass flow rate of refrigerant flowing into each subspace (71a ~ 71c) and a reference mass flow rate _{M R} In the operation state, the capacity of the outdoor heat exchanger (23) functioning as an evaporator is 95% or more of the maximum capacity in the operation state.

-Effect of the embodiment-
As described above, in the outdoor heat exchanger (23) of the present embodiment, the maximum value (that is, 90 kg) of the fluctuation range of the mass flow rate of the refrigerant flowing into the partial spaces (71a to 71c) of the main communication space (71). / h) is the reference mass flow rate _{M R,} and the the effective area a of the main communicating each subspace of the space (71) (71a ~ 71c) (1.91M R -22.7) or (1.96M _R +30. 8) It is as follows. Therefore, according to the present embodiment, the outdoor heat exchanger (23) is 95% of the maximum capacity under the heating low temperature condition in which the operating capacity of the compressor (21) provided in the refrigerant circuit (20) is the maximum value. The above can be demonstrated.

By the way, the outdoor heat exchanger (23) of the present embodiment has its capability in an operating condition in which the mass flow rate of the refrigerant flowing into each partial space (71a to 71c) of the main communication space (71) is less than the heating low temperature condition. May fall below 95% of maximum capacity. However, under such operating conditions, the operating capacity of the compressor (21) is smaller than the maximum value. For this reason, the heating capacity of the air conditioner (10) is increased by increasing the operating capacity of the compressor (21) under the operating conditions where the mass flow rate of the refrigerant flowing into each partial space (71a to 71c) is less than the heating low temperature condition. Capability can be secured.

Therefore, as in the present embodiment, the main communication space maximum value of the variation range of the mass flow rate of refrigerant flowing into each subspace (71a ~ 71c) (71) (i.e., 90 kg / h) a reference mass flow rate M _R If the effective cross-sectional area A of each partial space (71a to 71c) is set as follows, the capacity of the outdoor heat exchanger (23) can be fully exerted when the operating capacity of the compressor (21) reaches the maximum value. Can do. As a result, the heating capacity of the air conditioner (10) can be increased without increasing the size of the outdoor heat exchanger (23).

—Modification 1 of Embodiment—
In the outdoor heat exchanger (23) of the present embodiment, a value smaller than the maximum value of the fluctuation range of the mass flow rate of the refrigerant flowing into the partial spaces (71a to 71c) of the main communication space (71) is set to the reference mass flow rate M. _R and the second header collecting pipe (70) so that the effective area A of each partial space (71a to 71c) is (1.91M _R -22.7) or more and (1.96M _R +30.8) or less. ), The insertion length L of the flat tube (31) may be set.

Here, the time during which the compressor (21) of the refrigerant circuit (20) reaches the maximum capacity within one year is not so long. In other words, the compressor (21) is operated for a longer time than the maximum capacity than the maximum capacity.

Therefore, the most mass flow rate of refrigerant flowing into each subspace (71a ~ 71c) occurrences main communication through the high operating state of constant space (71) per year, it is conceivable to a reference mass flow rate M _R. The mass flow rate as a reference mass flow rate _{M R,} the effective area A of the subspaces (71a ~ 71c) is (1.91M _R -22.7) above (1.96M _R +30.8) as to become less If the insertion length L of the flat pipe (31) to the second header collecting pipe (70) is set, the outdoor heat exchanger (23) has the maximum capacity in the operating state in the operating state with the highest appearance rate in the year. 95% or more can be exhibited. Therefore, in this case, it is possible to improve the operation efficiency of the air conditioner (10) in the operation state having the highest appearance rate in the year, and to reduce the annual power consumption of the air conditioner (10).

-Modification Example 2-
In the outdoor heat exchanger (23) of the present embodiment, Formula 1 which is a linear approximate expression at which the capacity of the outdoor heat exchanger (23) is maximized in each of the heating low temperature condition, the heating rated condition, and the heating intermediate condition. Alternatively, the range of the effective area A of each partial space (71a to 71c) may be set.

That is, as shown in FIG. 8, one value within the fluctuation range of the mass flow rate of the refrigerant flowing into each partial space (71a to 71c) of the main communication space (71) of the second header collecting pipe (70) is used as a reference. in case of the mass flow rate _{M R,} the effective area a of the subspaces (71a ~ 71c) is (1.96M _R -b) above (1.96M _R + a) as to become less, the second header collecting pipe The insertion length L of the flat tube (31) with respect to (70) may be set. For example, the a = 30.0, if b = 25.0, if the mass flow rate of refrigerant flowing into each subspace (71a ~ 71c) of the main communication space (71) is the reference mass flow rate M _R The capacity of the outdoor heat exchanger (23) is approximately 95% or more of the maximum capacity in that case.

As described above, the present invention is useful for a heat exchanger including a plurality of flat tubes and a header collecting tube connected to each flat tube.

20 Refrigerant circuit 23 Heat exchanger (outdoor heat exchanger)
31 Flat pipe 36 Fin 60 First header collecting pipe 70 Second header collecting pipe 71a First partial space (distribution space)
71b Second partial space (distribution space)
71c Third partial space (distribution space)

Claims

A plurality of flat tubes (31), a first header collecting pipe (60) into which one end of each flat tube (31) is inserted, and the other end of each flat tube (31) are inserted A heat exchanger provided in a refrigerant circuit (20) for performing a refrigeration cycle, comprising a second header collecting pipe (70) and a plurality of fins (36) joined to the flat pipe (31),
The second header collecting pipe (70) communicates with the plurality of flat pipes (31), and when the heat exchanger functions as an evaporator, a circulation space (71a ~ 71c)
From the area of the cross section of the circulation space (71a to 71c) orthogonal to the axial direction of the second header collecting pipe (70), the portion of the flat pipe (31) located in the circulation space (71a to 71c) When the area obtained by subtracting the projected area onto the plane orthogonal to the axial direction of the second header collecting pipe (70) is the effective sectional area of the distribution space (71a to 71c),
The effective sectional area of the circulation space (71a to 71c) is set based on the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) when the heat exchanger functions as an evaporator. A heat exchanger characterized by
In claim 1,
When the heat exchanger functions as an evaporator and one value included in the fluctuation range of the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) is the reference mass flow rate M R [kg / h] In addition, the effective cross-sectional area A [mm 2 ] of the distribution space (71a to 71c) is (1.91M R −22.7) or more and (1.96M R +30.8) or less. Exchanger.
In claim 1,
When the heat exchanger functions as an evaporator and one value included in the fluctuation range of the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) is the reference mass flow rate M R [kg / h] the heat, characterized in that at the effective area a of the flow space (71a ~ 71c) [mm 2 ] is (1.96M R -25.0) above (1.96M R +30.0) below Exchanger.
In claim 2 or 3,
The reference mass flow rate M R [kg / h] is the maximum value of the fluctuation range of the mass flow rate of the refrigerant flowing into the circulation space (71a to 71c) when the heat exchanger functions as an evaporator. Features heat exchanger.
In any one of Claims 1 thru | or 4,
The first header collecting pipe (60) and the second header collecting pipe (70) are installed upright,
A heat exchanger, wherein when the heat exchanger functions as an evaporator, a refrigerant flows into the lower end of the circulation space (71a to 71c).