Heat exchanger, heat exchange system using heat exchanger, and air conditioner using heat exchanger

Abstract

To provide a heat exchanger formed so as to make a refrigerant flow passage turn back in a vertical direction, and retaining heat exchange efficiency of the heat exchanger by making a refrigerant evenly flow in a heat transfer pipe at a downstream side of the turn-back part.SOLUTION: A heat exchanger 100 includes: a first heat exchange part having a plurality of first heat transfer pipes aligned in the vertical direction, and having the same flow direction of refrigerants; a second heat exchange part arranged so as to be adjacent to the first heat exchange part in the vertical direction, and having a plurality of second heat transfer pipes aligned in the vertical direction, having the same flow direction of refrigerants and making the flow direction opposite to that of the first heat transfer pipe; and upper and lower turn-back parts 2X for connecting the downstream side end portions of the plurality of first heat transfer pipes with the upstream side end portions of the plurality of second heat transfer pipes, and turning back refrigerants flowing in the first heat transfer pipes in the vertical direction to make them flow into the second heat transfer pipes. The upper and lower turn-back parts have upper and lower turn-back flow passages 20X for establishing communication between the first heat transfer pipe and the second heat transfer pipe.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a heat exchanger, a heat exchange system using the heat exchanger, and an air conditioner using the heat exchanger. [Background technology]

[0002] Conventionally, there has been a heat exchanger, as shown in FIG. 7, which includes a plurality of heat transfer tubes arranged in a vertical direction and a top-bottom folded header connected to one end of the plurality of heat transfer tubes, and is configured so that refrigerant flowing through the plurality of heat transfer tubes provided on the lower side (first row) of the plurality of heat transfer tubes turns back vertically via the top-bottom folded header and flows into the plurality of heat transfer tubes provided on the upper side (second row) (for example, Patent Document 1).

[0003] The upper and lower folded headers of such a heat exchanger have spaces that communicate with the plurality of heat transfer tubes, and are configured to store the refrigerant supplied from the plurality of heat transfer tubes on the upstream side in the spaces within the upper and lower folded headers before diverting it to the plurality of heat transfer tubes on the downstream side. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2010-112581 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the heat exchanger described above, as shown in FIG. 8, the gas-liquid two-phase refrigerant may separate in the space within the upper and lower folded headers, causing liquid refrigerant to accumulate below the space, resulting in a so-called liquid pool.

[0006] When liquid pools form in this way, the gas-liquid two-phase refrigerant is unevenly distributed among the heat transfer tubes on the downstream side (second stage), which causes refrigerant flow bias in the heat exchanger and reduces heat exchange efficiency.

[0007] The present invention has been made to solve the above problems, and its main objective is to maintain the heat exchange efficiency of a heat exchanger in which the refrigerant flowing through multiple heat transfer tubes is folded back in the vertical direction, by allowing the refrigerant to flow evenly through the multiple heat transfer tubes downstream of the folded back portion. [Means for solving the problem]

[0008] That is, the heat exchanger according to the present invention comprises: a first heat exchange section having a plurality of first heat transfer tubes arranged side by side in the vertical direction and having the same refrigerant flow direction as each other; a second heat exchange section arranged adjacent to the first heat exchange section in the vertical direction and having a plurality of second heat transfer tubes arranged side by side in the vertical direction and having the same refrigerant flow direction as each of the first heat transfer tubes, the second heat exchange section being arranged side by side in the vertical direction and having the refrigerant flow direction opposite to that of each of the first heat transfer tubes; and an upper and lower folding section connecting the downstream ends of the plurality of first heat transfer tubes with the upstream ends of the plurality of second heat transfer tubes, so that the refrigerant that has flowed through the first heat transfer tubes turns back in the vertical direction and flows into the second heat transfer tubes, and the upper and lower folding section has upper and lower folding flow paths that individually connect each of the first heat transfer tubes and each of the second heat transfer tubes.

[0009] In a heat exchanger configured in this manner, the first heat transfer tubes of the first heat exchange section and the second heat transfer tubes of the second heat exchange section are individually connected in the upper and lower turn-back flow paths, so that the refrigerant flowing through the first heat transfer tubes of the first heat exchange section flows to the corresponding second heat transfer tubes without merging or splitting at the upper and lower turn-back sections. In this way, no merging or splitting occurs at the upper and lower turn-back sections, which could cause flow deviation, and it is possible to prevent a decrease in the heat exchange efficiency of the heat exchanger due to flow deviation. In particular, when a two-phase gas-liquid refrigerant is flowing in the first heat exchange section, the two-phase gas-liquid refrigerant does not merge at the upper and lower turning sections, thereby preventing a decrease in heat exchange efficiency due to liquid pooling as described above.

[0010] In addition, it is desirable that the number of the first heat transfer tubes and the number of the second heat transfer tubes are the same, and that the upper and lower folded portion have a plurality of the upper and lower folded flow paths that individually connect the plurality of first heat transfer tubes and the plurality of second heat transfer tubes. In this case, all of the first heat transfer tubes in the first heat exchange section and all of the second heat transfer tubes in the second heat exchange section are connected in a one-to-one relationship via the upper and lower folded flow paths, so that the refrigerant flowing through all of the first heat transfer tubes flows to the corresponding second heat transfer tubes without merging or dividing at the upper and lower folded flow paths. This more reliably prevents uneven flow in the refrigerant flow paths of the heat exchanger, and maintains a higher level of heat exchange efficiency.

[0011] However, in multiple refrigerant flow paths formed by multiple first heat transfer tubes and multiple second heat transfer tubes individually communicating with each other via upper and lower folded flow paths, if the flow path lengths differ from one another, a difference in pressure loss will occur between the flow paths, resulting in a problem of drift. Therefore, it is desirable that the upper and lower turn-back flow paths communicate with the first heat transfer tube and the second heat transfer tube that are arranged at the same positions in each heat exchange section. This makes it easier to make the lengths of the refrigerant flow paths uniform, reducing uneven flow.

[0012] It is also desirable that the lengths of the upper and lower folded flow paths are substantially the same. This makes it possible to configure the lengths of each refrigerant flow path formed by connecting the first heat transfer tube and the second heat transfer tube via the upper and lower folded flow paths to be approximately the same, making it less likely that differences in pressure loss will occur in each refrigerant flow path and reducing drift.

[0013] It is desirable that the system further comprises a third heat exchange section that is arranged adjacent to the second heat exchange section in the horizontal direction and that has a plurality of third heat transfer tubes that are arranged side by side in the vertical direction and have the same refrigerant flow direction but opposite to that of each of the second heat transfer tubes; and a horizontal turning section that connects the downstream end of the second heat transfer tube with the upstream end of the third heat transfer tube and turns the refrigerant that has flowed through the second heat transfer tubes in the horizontal direction so that it flows into the third heat transfer tube, and that the horizontal turning section has horizontal turning flow paths that individually connect each of the second heat transfer tubes and each of the third heat transfer tubes. In this case, the second heat transfer tubes of the second heat exchange section and the third heat transfer tubes of the third heat exchange section are individually connected in the horizontal turning flow path, so that the refrigerant flowing through the second heat transfer tubes of the second heat exchange section flows to the corresponding third heat transfer tubes without merging or re-splitting at the horizontal turning section. This allows the gas-liquid two-phase refrigerant to flow evenly through the third heat transfer tubes of the third heat exchange section, maintaining the heat exchange efficiency of the heat exchanger.

[0014] When a heat exchanger is used as an evaporator, the vapor temperature decreases due to pressure loss as the refrigerant flows through the heat transfer tube, so the temperature of the gas-liquid two-phase refrigerant introduced into the heat transfer tube decreases as it travels downstream. Therefore, it is desirable that the heat exchanger is an evaporator, the first heat exchange section and the second heat exchange section are arranged on the windward side, and the third heat exchange section is arranged on the leeward side. In this case, the temperature difference between the refrigerant and the air can be made larger than when the first heat exchange section and the second heat exchange section are arranged on the downwind side, and the heat exchange efficiency is improved.

[0015] However, a temperature difference occurs in the refrigerant flowing between the first heat exchange section located upstream and the second heat exchange section located downstream. Because the first and second heat exchange sections are vertically adjacent, this temperature difference can lead to heat exchange between the first and second heat transfer tubes located at the ends of each heat exchange section, for example, via fins. If heat exchange occurs between the first and second heat exchange sections in this way, heat loss increases, reducing the heat exchange efficiency of the entire heat exchanger.

[0016] Therefore, it is desirable that one or more dummy heat transfer tubes, through which no refrigerant flows, be arranged between the first heat exchange section and the second heat exchange section. In this case, the dummy heat transfer tube can prevent heat exchange between the first heat exchange section and the second heat exchange section, so that the heat exchange efficiency of the heat exchanger can be maintained.

[0017] A heat exchange system may be configured by stacking a plurality of the above-described heat exchangers in the vertical direction so that they are plane-symmetrical to one another when viewed horizontally. In such a heat exchange system, the same heat exchange sections of each heat exchanger can be stacked vertically, thereby reducing the temperature difference between adjacent areas of two different heat exchangers and reducing the heat loss caused by heat exchange between these heat exchangers.

[0018] In a heat exchanger having a plurality of rows of heat exchange units arranged in the horizontal direction as described above, conventionally, the refrigerant outlet pipe and discharge pipe are connected to the heat exchange units in different rows. In this conventional connection of the outlet and discharge pipes, the discharge pipe is located on the downwind side when used as either an evaporator or a condenser. This results in an insufficient temperature difference between the refrigerant and the air near the discharge pipe, and a problem occurs when attempting to ensure a sufficient degree of superheat at the evaporator outlet or a sufficient degree of subcooling at the condenser outlet. This decrease in heat exchange efficiency becomes particularly noticeable when the room temperature approaches the set temperature and the temperature difference between the refrigerant and the air in the indoor heat exchanger becomes even smaller (during so-called sluggish operation).

[0019] When used in indoor units, in order to prevent problems such as uneven temperature of the blown air and splashing of condensation water, it is necessary to operate the unit while ensuring both the degree of superheat at the evaporator outlet and the degree of subcooling at the condenser outlet. With the connection of the outlet and exhaust pipes of conventional heat exchangers, it is impossible to avoid a decrease in heat exchange efficiency when used as either an evaporator or a condenser.

[0020] In order to solve such problems, it is desirable that the heat exchanger of the present invention further comprises: a downwind heat exchange unit group consisting of a plurality of downwind heat exchange units, including the first heat exchange unit and the second heat exchange unit, arranged in a vertical direction; an upwind heat exchange unit group consisting of a plurality of upwind heat exchange units arranged in a vertical direction and positioned upwind of the downwind heat exchange units; a turn-around portion including the upper and lower turn-around portions, connecting the upwind heat exchange units and the downwind heat exchange units to form a continuous refrigerant flow path together with them; an inlet pipe connected to one of the plurality of upwind heat exchange units constituting the upwind heat exchange unit group and introducing refrigerant into one end of the refrigerant flow path; and a discharge pipe connected to another of the plurality of upwind heat exchange units constituting the upwind heat exchange unit group and discharging refrigerant from the other end of the refrigerant flow path.

[0021] With this configuration, since the discharge pipe is connected to the windward heat exchange unit group, the temperature difference between the refrigerant and the air near the discharge pipe can be increased, and even when the refrigerant is highly superheated in the discharge pipe, a sufficient temperature difference between the refrigerant and the air can be ensured to ensure heat exchange efficiency. In particular, even during slow operation, which accounts for the majority of air conditioning operating hours, the temperature difference between the refrigerant and the air can be kept as large as possible to ensure heat exchange efficiency, thereby significantly improving the heating and cooling efficiency of air conditioners equipped with such heat exchangers. In addition, because both the discharge pipe and the inlet pipe are positioned on the windward side, even when the refrigerant flow direction is reversed to switch operation between the evaporator and the condenser, a large temperature difference between the refrigerant and the air near the discharge pipe can be maintained, making it suitable for use in indoor units.

[0022] Specifically, it is desirable that the heat exchanger is an evaporator, and that the temperature of the degree of superheat of the refrigerant discharged from the discharge pipe is controlled to be equal to or higher than a predetermined value.

[0023] Furthermore, the air conditioner according to the present invention is characterized by being equipped with the heat exchanger described above, and such an air conditioner can exert the effects of the heat exchanger described above. [Effects of the Invention]

[0024] According to the present invention configured in this manner, in a heat exchanger in which the refrigerant flowing through multiple heat transfer tubes is configured to turn back and forth in the vertical direction, the refrigerant can be made to flow evenly through the multiple heat transfer tubes downstream of the turning portion, thereby maintaining the heat exchange efficiency of the heat exchanger. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a schematic diagram showing an oblique view of an overall configuration of a heat exchanger according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic front view of the heat exchanger according to the embodiment. [Figure 3] FIG. 10 is an explanatory diagram illustrating a case where the heat exchanger in the embodiment functions as a condenser. [Figure 4] FIG. 4 is an enlarged schematic view of a folded portion of the heat exchanger in the embodiment. [Figure 5] 10A and 10B are front and rear views of a heat exchanger according to another embodiment. [Figure 6]FIG. 10 is an enlarged schematic view of a folded portion of a heat exchanger according to another embodiment. [Figure 7] FIG. 10 is a diagram showing the flow of refrigerant in a conventional heat exchanger. [Figure 8] FIG. 10 is a diagram showing the flow of refrigerant in a folded header in a conventional heat exchanger. [Figure 9] FIG. 10 is a schematic oblique view of the overall configuration of an indoor heat exchanger according to a second embodiment. [Figure 10] 3A and 3B are front and rear views of the indoor heat exchanger in the embodiment; [Figure 11] 2 is a schematic diagram of the air conditioner (in cooling operation) according to the embodiment. FIG. [Figure 12] FIG. 4 is an explanatory diagram illustrating a case where the indoor heat exchanger in the embodiment functions as an evaporator. [Figure 13] FIG. 10 is an explanatory diagram of a conventional indoor heat exchanger functioning as an evaporator. [Figure 14] FIG. 10 is an explanatory diagram illustrating a case where the indoor heat exchanger in the embodiment functions as a condenser. DETAILED DESCRIPTION OF THE INVENTION

[0026] A first embodiment of a heat exchanger according to the present invention will be described below with reference to the drawings.

[0027] [First embodiment] 1. Overall structure The heat exchanger according to this embodiment constitutes an air conditioner having a refrigerant circuit, and is used as either an outdoor heat exchanger or an indoor heat exchanger, or both.

[0028] As shown in FIG. 1, this heat exchanger 100 comprises a plurality of heat exchange sections 1 each having a plurality of heat transfer tubes 10 arranged in a vertical direction, a return section 2 connecting two adjacent heat exchange sections 1, an inlet pipe 3 connected to one of the plurality of heat exchange sections 1 for introducing a refrigerant into the heat exchanger 100, and an outlet pipe 4 connected to another heat exchange section 1 for discharging the refrigerant from the heat exchanger 100.

[0029] The refrigerant introduced into the heat exchanger 100 from the inlet pipe 3 flows through a series of refrigerant flow paths L formed by connecting a plurality of heat exchange sections 1 via the turn-back sections 2, and is discharged from the outlet pipe 4.

[0030] Hereinafter, the extending direction of the heat transfer tubes 10 is referred to as the left-right direction, and the direction perpendicular to the up-down and left-right directions is referred to as the front-rear direction. The front-rear direction is the direction in which air that exchanges heat with the refrigerant flows in the heat exchanger 100.

[0031] When the heat exchanger 100 of this embodiment functions as a condenser, of the multiple heat exchange sections 1 arranged in two rows in the front-to-rear direction, the heat exchange section 1 on the upstream side (the side where the inlet pipe 3 is provided) is positioned on the downwind side, and the heat exchange section 1 on the downstream side (the side where the outlet pipe 4 is provided) is positioned on the upwind side.

[0032] 2.Device configuration 2-1.Heat exchange section 1 1 and 2, the heat exchange section 1 has a plurality of heat transfer tubes 10 arranged vertically at a predetermined interval and extending in the same direction in the left-right direction. The heat transfer tubes 10 are flattened and arranged so that the flat surfaces of the heat transfer tubes 10 aligned vertically face each other. The heat transfer tubes 10 are perforated tubes having a plurality of holes therein through which the refrigerant flows in the extension direction of the heat transfer tubes 10.

[0033] A refrigerant is introduced into the heat transfer tubes 10 of the heat exchange unit 1 from either one end 11 or the other end 12 in the left-right direction of the heat exchange unit 1. Therefore, the refrigerant flows in the same direction through the heat transfer tubes 10 included in one heat exchange unit 1.

[0034] The heat exchanger 100 of this embodiment includes six heat exchange sections 1A to 1F. Each heat exchange section 1 has the same number (six in this example) of heat transfer tubes 10, and the dimensions (length, width, thickness) of each heat transfer tube 10 are configured to be approximately the same. Note that each heat exchange section may have any number of heat transfer tubes as long as they are plural.

[0035] As shown in Figures 1 and 2, the six heat exchange sections 1A to 1F of this embodiment are arranged so that the extension directions (flow directions of the internal flow paths) of the heat transfer tubes 10A to 10F are parallel to each other, with three arranged vertically and two arranged front to back.

[0036] That is, the heat exchange sections 1A-1C and 1D-1F are stacked in three vertical stages and arranged in two rows, one behind the other. The n-th stages of the three heat exchange sections 1 arranged in two rows are adjacent to each other in the front-to-back direction at the same height. For example, in the first stage, the six heat transfer tubes 10A of the heat exchange section 1A and the six heat transfer tubes 10F of the heat exchange section 1F correspond one-to-one in the front-to-back direction and are arranged at the same height.

[0037] The three overlapping heat exchange sections 1A to 1C and 1F to 1D are counted as the first to third sections from the bottom. The row of heat exchange sections 1A to 1C is the first row, and the row of heat exchange sections 1F to 1D is the second row.

[0038] 2-2. Folded section 2 1 and 2, the folded portion 2 connects each of two adjacent heat exchange units 1 in the up-down direction or the front-rear direction. The folded portion 2 extends in the up-down direction so as to surround the ends of the two adjacent heat exchange units 1 on the same side in the left-right direction.

[0039] The turn-back section 2 connects the downstream end of the heat transfer tube 10 of the heat exchange section 1 located upstream of two adjacent heat exchange sections 1 to the upstream end of the heat transfer tube 10 of the heat exchange section 1 located downstream, and turns back the refrigerant that has flowed through the upstream heat transfer tube 10 and causes it to flow into the downstream heat transfer tube 10.

[0040] At each turn-back portion 2, the refrigerant flow path L is turned back, so that the refrigerant flows in the opposite directions between two adjacent heat exchange portions 1 connected at the turn-back portion 2.

[0041] The heat exchanger 100 of this embodiment includes five turn-back portions 2, and six heat exchange sections 1A to 1F are connected in series via these turn-back portions 2.

[0042] In this embodiment, the turning portions 2 include vertical turning portions 2X that turn the refrigerant flow path L in the vertical direction, and horizontal turning portions 2Y that turn the refrigerant flow path L in the horizontal direction.

[0043] Four upper and lower folded portions 2X are provided, and they connect, in a one-to-one relationship, the ends on the same side of two vertically adjacent heat exchange sections 1. For example, the upper and lower folded portion 2X connects one end 11 of the first-stage heat exchange section 1A to one end 11 of the second-stage heat exchange section 1B.

[0044] One horizontal folded portion 2Y is provided, and connects, in a one-to-one relationship, the ends on the same side of two adjacent heat exchange units 1 in the front-to-rear direction. For example, the horizontal folded portion 2Y connects one end 11 of the heat exchange unit 1C in the first row to one end 11 of the heat exchange unit 1D in the second row.

[0045] 2-3. Inlet pipe 3 and outlet pipe 4 As shown in Figures 1 and 2, the inlet pipe 3 introduces a refrigerant into the heat exchanger 100, and is connected to one end 11 or the other end 12 of one heat exchange section 1 to circulate the refrigerant through the multiple heat transfer pipes 10 of that heat exchange section 1.

[0046] In this embodiment, the inlet pipe 3 is connected to the other end 12 of the heat exchange unit 1A, and causes the refrigerant to flow through the heat transfer pipes 10A. Here, one inlet pipe 3 communicates with a flow divider 5 provided at the other end 12 of the heat exchange unit 1A, and the refrigerant supplied from the inlet pipe 3 is divided into six heat transfer pipes 10A via the flow divider 5.

[0047] As shown in Figures 1 and 2, the discharge pipe 4 discharges the refrigerant from the heat exchanger 100, and is connected to one end 11 or the other end 12 of one heat exchange section 1 to discharge the refrigerant flowing through the multiple heat transfer tubes 10 of that heat exchange section 1 to the outside.

[0048] The discharge pipe 4 in this embodiment is connected to the other end 12 of the heat exchange unit 1F and discharges the refrigerant flowing through the heat transfer tubes 10F to the outside. Here, six discharge pipes 4 are provided, and the refrigerant that has flowed through the six heat transfer tubes 10F is configured to be discharged from the discharge pipes 4 that correspond one-to-one to each heat transfer tube 10F.

[0049] 2-4. Refrigerant flow path L As shown in FIGS. 1 and 2, the refrigerant flow path L is a series of flow paths through which the refrigerant flows, which are formed by connecting a plurality of heat exchange sections 1 via turn-back sections 2.

[0050] In this embodiment, six heat exchange units 1A to 1F are connected in sequence via five turn-back units 2, thereby forming a series of refrigerant flow paths L.

[0051] In the refrigerant flow path L configured in this manner, an inlet pipe 3 is connected to the heat exchange section 1A and an outlet pipe 4 is connected to the heat exchange section 1F, so that the refrigerant flows sequentially through each heat exchange section 1 from the upstream heat exchange section 1A to the downstream heat exchange section 1F.

[0052] Here, the state of the refrigerant changes when the heat exchanger 100 functions as a condenser will be described with reference to FIG.

[0053] In this embodiment, first, the gaseous refrigerant from the inlet pipe 3 is divided by the flow divider 5 and introduced into the heat transfer tubes 10A of the heat exchange section 1A arranged in the first row and first stage of the heat exchange section 1. The gaseous refrigerant that has exchanged heat with air in each heat transfer tube 10A is introduced into the heat transfer tubes 10B of the heat exchange section 1B arranged in the second row and first stage through the upper and lower turn-back portions 2X.

[0054] In this embodiment, the refrigerant changes phase from a gas state to a two-phase gas-liquid state in heat exchange unit 1B. The two-phase refrigerant that has exchanged heat with air in heat transfer tube 10B is introduced into heat exchange unit 1C in the third stage of the first row via upper and lower turn-back portions 2X, into heat exchange unit 1D in the third stage of the second row via horizontal turn-back portion 2Y, and into heat exchange unit 1E in the second stage of the second row via upper and lower turn-back portions 2X. The two-phase refrigerant that has exchanged heat with air in each heat transfer tube 10E is introduced into the heat transfer tubes 10B of heat exchange unit 1F located in the first stage of the second row via upper and lower turn-back portions 2X.

[0055] In this embodiment, the refrigerant is configured to change phase from a gas-liquid two-phase state to a liquid state in the heat exchange section 1F. The liquid refrigerant that has flowed through the heat transfer tube 10F is discharged from the discharge tube 4.

[0056] In this embodiment, in order to maximize the temperature difference between the refrigerant flowing through the heat transfer tube 10 and the air passing through the heat exchange unit 1 in each of the two rows of heat exchange units 1, the heat exchange unit 1 in the first row, which is upstream of the refrigerant flow path L, is positioned on the downwind side, and the heat exchange unit 1 in the second row, which is downstream, is positioned on the upwind side.

[0057] 2-5. Turn-around flow path 20 As shown in Figures 1 and 2, the turn-back section 2 has a turn-back flow path 20 that individually connects the heat transfer tubes 10 of the heat exchange section 1 located upstream and the heat transfer tubes 10 of the heat exchange section 1 located downstream of two adjacent heat exchange sections 1.

[0058] In this embodiment, a plurality of return flow paths 20 are formed as cavities in the internal space of the return section 2 made of a block body. Note that the return flow paths 20 may be formed by combining the same number of pipe members as the heat transfer tubes 10.

[0059] Here, six mutually independent return flow paths 20 are formed in each return section 2, and the six heat transfer tubes 10 of the heat exchange section 1 located upstream are connected to the six heat transfer tubes 10 of the heat exchange section 1 located downstream in a one-to-one relationship.

[0060] As shown in FIG. 4, the return flow path 20 of this embodiment connects the heat transfer tubes 10 that are arranged in the same position (for example, the same row counting from the top or bottom) in the vertical direction of each heat exchange section 1 in two adjacent heat exchange sections 1.

[0061] Here, one of the upper and lower turn-back flow paths 20X provided in the upper and lower turn-back section 2X connects the heat transfer tube 10A arranged first from the top in the heat exchange section 1A to the heat transfer tube 10B arranged first from the top in the heat exchange section 1B, as shown in Figure 4.

[0062] Furthermore, one of the horizontal turning flow paths 20Y provided in the horizontal turning section 2Y connects the heat transfer tube 10C arranged third from the bottom in the heat exchange section 1C with the heat transfer tube 10D arranged third from the bottom in the heat exchange section 1D, as shown in FIG. 1.

[0063] The plurality of turning flow paths 20 in each turning portion 2 are configured so that the flow path lengths thereof are substantially the same.

[0064] In this way, the return flow path 20 connects the six heat transfer tubes 10 of each heat exchange section 1 in a one-to-one relationship, thereby forming six independent refrigerant flow paths L passing through the six heat exchange sections 1.

[0065] 3.Effects In a heat exchanger 100 configured in this manner, refrigerant of approximately the same temperature flows through the multiple heat transfer tubes 10 arranged vertically in each heat exchange section 1, thereby reducing the temperature difference between adjacent heat transfer tubes 10 in each heat exchange section 1 and reducing heat loss caused by heat exchange between adjacent heat transfer tubes 10.

[0066] The refrigerant that flows through the multiple heat transfer tubes 10 of the upstream heat exchange section 1 flows into the corresponding multiple heat transfer tubes 10 of the adjacent downstream heat exchange section 1 without merging or branching through the multiple turning flow paths 20 of the turning section 2. Therefore, even if a gas-liquid two-phase refrigerant flows through the upstream heat transfer tube 10, the gas-liquid two-phase refrigerant can be made to flow evenly through the multiple heat transfer tubes 10 on the downstream side, thereby maintaining the heat exchange efficiency of the heat exchanger 100.

[0067] Since the return flow paths 20 connect two heat transfer tubes 10 at the same arrangement position in adjacent heat exchange sections 1 in a one-to-one relationship, the lengths of the refrigerant flow paths L can be easily made uniform.

[0068] Furthermore, since the multiple return flow paths 20 of one return section 2 connecting two adjacent heat exchange sections 1 are approximately the same length, differences in pressure loss are less likely to occur in each refrigerant flow path, and drift can be reduced.

[0069] Since both the inlet pipe 3 and the outlet pipe 4 are arranged together in the first stage on one side in the left-right direction of the heat exchanger 100, piping work and the like is simple.

[0070] [Other embodiments] In the heat exchanger 100 of the above embodiment, the refrigerant flow paths L are configured so as not to merge or split at all of the turn-around sections 2, but it is sufficient that the refrigerant flow paths L are configured so as not to merge or split at at least one of the upper and lower turn-around sections 2X.

[0071] Furthermore, if there is a return flow path 20 that individually connects at least one heat transfer tube 10 of one heat exchange section 1 to one heat transfer tube of another adjacent heat exchange section 1, it is possible to suppress the occurrence of drift in the refrigerant flow path L formed by the heat transfer tube, thereby achieving the effect of maintaining heat exchange efficiency.

[0072] The heat exchanger 100 may include a plurality of heat exchange sections 1, and at least two of the plurality of heat exchange sections 1 may be adjacent to each other in the vertical direction and connected by a vertical fold section 2X that does not include a junction or a divider as described above. The arrangement of the heat exchange sections 1 (number of rows and columns) may also be designed appropriately according to the application.

[0073] In the above embodiment, the air flow direction when the heat exchanger 100 functions as a condenser has been described. However, when the heat exchanger 100 functions as an evaporator, it is preferable that the first row, which is on the upstream side of the refrigerant flow path L, is positioned on the upwind side, and the second row, which is on the downstream side, is positioned on the downwind side. In this case, the temperature difference between the refrigerant and the air can be made larger than when the first heat exchange section and the second heat exchange section are arranged on the downwind side, and the heat exchange efficiency is improved.

[0074] 5, the heat exchanger 100 preferably has one or more dummy heat transfer tubes 6, through which no refrigerant flows, between vertically adjacent heat exchange sections 1. Here, dummy heat transfer tubes 6 are provided between heat exchange section 1A and heat exchange section 1B, and between heat exchange section 1E and heat exchange section 1F.

[0075] The dummy heat transfer tube 6 is, for example, a heat transfer tube configured not to communicate with the turning flow path 20 of the turning portion 2. The dummy heat transfer tube 6 may be a heat transfer tube with the internal holes sealed.

[0076] In this case, the dummy heat transfer tubes 6 can prevent heat exchange between two heat exchange sections 1 that are adjacent to each other vertically, so that the heat exchange efficiency of the heat exchanger 100 can be maintained.

[0077] In particular, when a gas-liquid two-phase refrigerant flows in one of two adjacent heat exchange sections 1 and a gaseous or liquid refrigerant flows in the other, the temperature difference between these heat exchange sections 1 becomes large, so it is advisable to provide a dummy heat transfer tube 6 between such heat exchange sections 1.

[0078] A heat exchange system may be configured by stacking a plurality of heat exchangers of the above-described embodiment vertically as a single module, in which case adjacent heat exchangers are configured to be plane-symmetrical to each other when viewed horizontally.

[0079] This allows the same heat exchange sections of each heat exchanger to be stacked on top of each other in the vertical direction, thereby reducing the temperature difference between adjacent areas of two different heat exchangers and reducing the heat loss caused by heat exchange between these heat exchangers.

[0080] In the above embodiment, the refrigerant is introduced from the heat exchanger 1A, but the refrigerant may be introduced from the heat exchanger 1F side.

[0081] In the above embodiment, the upper and lower folded flow paths 20X connect the heat transfer tubes 10 that are arranged in the same position in two adjacent heat exchange sections 1, but the upper and lower folded flow paths 20X may also connect the heat transfer tubes 10 that are arranged in different positions.

[0082] Even in this case, if the heat transfer tubes 10 are connected in a manner such as shown in Fig. 6, the total path length of the plurality of return paths 20 included in the refrigerant path L can be configured to be approximately the same for each refrigerant path L. Even in this way, the path lengths of the refrigerant path L can be made approximately the same relatively easily, thereby reducing the difference in pressure loss between the refrigerant path L and mitigating drift.

[0083] [Second embodiment] In the heat exchanger 100 of the first embodiment, of the multiple heat exchange sections 1 arranged vertically and front to back, an inlet pipe 3 is connected to the heat exchange section 1A in the front row, and an outlet pipe 4 is connected to the heat exchange section 1F in the rear row, and the inlet pipe 3 and the outlet pipe 4 are each connected to the heat exchange sections 1 in different rows front to back. In contrast to this, in an indoor heat exchanger 200 of the second embodiment, as shown in FIG. 9, both the inlet pipe 3 and the outlet pipe 4 are connected to heat exchange sections 1 aligned vertically in the same row.

[0084] The indoor heat exchanger 200 is provided inside the indoor unit. Hereinafter, a case where the indoor heat exchanger 200 functions as an evaporator will be described in detail.

[0085] As shown in Figures 9 and 10, the indoor heat exchanger 200 of the second embodiment comprises four heat exchange sections 1G to 1J arranged front to back and top to bottom, three folding sections 2 connecting these heat exchange sections 1 to form a series of refrigerant flow paths L together with each heat exchange section, an inlet pipe 3 connected to one heat exchange section 1 to introduce refrigerant into one end of the refrigerant flow path L, and a discharge pipe 4 connected to another heat exchange section 1 to discharge refrigerant from the other end of the refrigerant flow path L.

[0086] In the second embodiment, the air passing through the indoor heat exchanger 200 to exchange heat with the refrigerant flows from the front row side to the rear row side of the heat exchange units 1 arranged in the front-to-rear direction. Hereinafter, the front row side will also be referred to as the upwind side, and the rear row side will also be referred to as the downwind side.

[0087] The configuration of each of the heat exchange units 1G to 1J is the same as that of the heat exchange unit 1 in the first embodiment. The four heat exchange units 1G to 1J in the second embodiment are arranged so that the extension directions of the heat transfer tubes 10 are parallel to each other, stacked in two rows in the vertical direction, and aligned in two rows in the front-to-rear direction. The number of heat exchange units 1 constituting the indoor heat exchanger 200 is not limited to four. The heat exchange units 1 may be aligned in two or more rows in the front-to-rear direction and in two or more rows in the top-to-bottom direction.

[0088] Here, the heat exchange sections 1G and 1H arranged vertically in the front row located on the windward side are collectively referred to as the windward heat exchange section group 14, and the heat exchange sections 1I and 1J arranged vertically in the rear row located on the leeward side are collectively referred to as the leeward heat exchange section group 15.

[0089] As in the first embodiment, the turn-back portion 2 individually connects the heat transfer tubes 10 of adjacent heat exchange units 1. Here, one upper and lower turn-back portion 2X and two horizontal turn-back portions 2Y are provided as the turn-back portion 2. The upper and lower turn-back portion 2X connects the heat exchange unit 1I and the heat exchange unit 1J. One horizontal turn-back portion 2Y connects the heat exchange unit 1G and the heat exchange unit 1I, and the other horizontal turn-back portion 2Y connects the heat exchange unit 1H and the heat exchange unit 1J.

[0090] 9, the inlet pipe 3 and the outlet pipe 4 of the second embodiment are each connected to the upwind heat exchanger group 14. More specifically, the inlet pipe 3 is connected to the heat exchanger 1G arranged on the lower side of the upwind heat exchanger group 14, and the outlet pipe 4 is connected to the heat exchanger 1H arranged on the upper side, so that the outlet pipe 4 is arranged above the inlet pipe 3 in the vertical direction.

[0091] In the indoor heat exchanger 200 configured in this manner, the refrigerant introduced into the heat exchanger 1G from the inlet pipe 3 flows through the heat exchange section 1I, the heat exchange section 1J, and the heat exchange section 1H in this order, and is discharged from the outlet pipe 4.

[0092] The air conditioner AC of the second embodiment controls the degree of superheat of the refrigerant discharged from the discharge pipe 4 of the indoor heat exchanger 200 functioning as an evaporator so that the degree of superheat is equal to or greater than a predetermined value. The air conditioner AC will be described below with reference to FIG.

[0093] The air conditioner AC has a refrigerant circuit R configured by connecting an indoor heat exchanger 200, an outdoor heat exchanger 300, a compressor 301, an expansion valve 302, a four-way valve (not shown), etc. via refrigerant piping, and a flow rate control unit 400 that controls the flow rate of the refrigerant flowing through the refrigerant circuit R. Figure 10 shows the direction of refrigerant flow when the indoor heat exchanger 200 functions as an evaporator, i.e., when the air conditioner AC is operating in cooling mode.

[0094] The indoor heat exchanger 200 is provided inside the housing of the indoor unit installed inside the building, and the outdoor heat exchanger 300, compressor 301, expansion valve 302, and four-way switching valve are provided inside the housing of the outdoor unit installed outside the building.

[0095] The outdoor heat exchanger 300 is a heat exchanger equipped with a plurality of heat exchange units arranged vertically and front to back, and its inlet pipe and outlet pipe are connected to the heat exchange units in different rows. The inlet pipe of the outdoor heat exchanger 300, which functions as a condenser, is located on the downwind side, and the outlet pipe is located on the upwind side.

[0096] Structurally, the flow control unit 400 is a so-called computer having a CPU, memory, I / O interface, communication interface, etc., and performs its functions by operating the CPU and peripheral devices in cooperation with each other according to a predetermined program stored in the memory.

[0097] The flow rate control unit 400 controls the amount of refrigerant introduced into the indoor heat exchanger 200, for example, by controlling the valve opening of the expansion valve 302 and the operation of the compressor 301, and controls the degree of superheat of the refrigerant discharged from the discharge pipe 4 of the indoor heat exchanger 200 to a predetermined value or higher. The degree of superheat is controlled to, for example, about 1 to 6 degrees.

[0098] More specifically, as shown in FIG. 12(a), the flow control unit 400 controls the flow rate of the refrigerant so that the refrigerant flowing through each heat transfer tube 10 is superheated (so that the refrigerant temperature exceeds the saturation temperature) in a predetermined region (hereinafter referred to as the superheat ensuring region SH) set on one end side of the heat exchange unit 1H.

[0099] The superheat ensuring region SH is set over a predetermined length from one end of the heat exchange section 1H to which the exhaust pipe 4 is connected toward the other end.

[0100] Hereinafter, with reference to Figs. 12(b) and 13, it will be described that the indoor heat exchanger 200 can ensure a large temperature difference between the refrigerant and the air near the discharge pipe 4 compared to conventional heat exchangers.

[0101] FIG. 12(b) is a graph showing the temperature change of the refrigerant and air flowing through the upper stage (heat exchangers 1H, 1J) of the indoor heat exchanger 200 configured as described above. From FIG. 12(b), it can be seen that even if the refrigerant is superheated in the heat exchange section 1H on the windward side, it is easy to ensure a sufficient temperature difference between the superheated refrigerant and the air on the windward side, which has a higher temperature.

[0102] Fig. 13(a) is a schematic diagram of a conventional indoor heat exchanger in which the inlet pipe is connected to the front-row (upwind) heat exchanger and the outlet pipe is connected to the rear-row (downwind) heat exchanger, and Fig. 13(b) is a graph showing the temperature changes of the air and refrigerant flowing through the heat exchanger when the refrigerant is superheated near the outlet pipe of such a heat exchanger. Figure 13(b) shows that when the refrigerant is superheated in the heat exchange section on the downwind side, it is difficult to ensure a sufficient temperature difference between the superheated refrigerant and the downwind air, which has a lower temperature due to heat exchange on the upwind side.

[0103] The flow control unit 400 controls the amount of refrigerant introduced into the outdoor heat exchanger 300, for example by controlling the operation of the compressor 301, so that the refrigerant discharged from the discharge pipe of the outdoor heat exchanger 300 has a degree of subcooling (so that the refrigerant temperature is below the saturation temperature).

[0104] [effect] In the indoor heat exchanger 200 of the second embodiment, the discharge pipe 4 is connected to the heat exchange section 1H on the windward side, so that the temperature difference between the refrigerant and the air near the discharge pipe 4 can be made as large as possible, and even when the refrigerant is highly superheated in the discharge pipe 4, the temperature difference between the refrigerant and the air can be sufficiently secured to ensure heat exchange efficiency.

[0105] Furthermore, since the introduction pipe 3 is also arranged on the windward side, a temperature difference in the vicinity of the introduction pipe 3 can also be ensured.

[0106] The refrigerant that flows through each heat transfer tube 10 in the upstream heat exchange sections 1G, 1I, and 1J flows to each heat transfer tube 10 in the heat exchange section 1H without merging or splitting at the turning section 2, so that the temperature change along the flow direction of the refrigerant flowing through each heat transfer tube 10 is uniform. This reduces variation in the position where the refrigerant exceeds the saturation temperature (the position where the degree of superheat is achieved) for each heat transfer tube 10. As a result, with the indoor heat exchanger 200 of the second embodiment, the refrigerant flowing through each heat transfer tube 10 can be reliably superheated even if the superheat assurance region SH is made small. Furthermore, by reducing the superheat ensuring region SH where the temperature difference with the air is small, the heat exchange efficiency of the entire heat exchanger can be ensured.

[0107] Since the discharge pipe of the outdoor heat exchanger 300 is provided on the upwind side, even if the degree of subcooling is increased in this discharge pipe, a sufficient temperature difference between the refrigerant and the air near this discharge pipe can be ensured.

[0108] [When functioning as a condenser] A case where the indoor heat exchanger 200 of the second embodiment functions as a condenser, that is, a case where the air conditioner AC is in heating operation, will be described with reference to FIG.

[0109] When functioning as a condenser, the refrigerant flow direction is reversed from when it functions as an evaporator, and the functions of the inlet pipe and outlet pipe are swapped. Specifically, in Figure 14, reference numeral 4 indicates the inlet pipe, and reference numeral 3 indicates the outlet pipe. When the discharge pipe 3 is positioned above the inlet pipe 4 in the vertical direction, the condensed liquid refrigerant must flow against gravity, which can cause the refrigerant to stagnate in some areas, significantly reducing the heat exchange efficiency. However, in the heat exchanger 200 functioning as a condenser shown here, the inlet pipe 4 is positioned vertically above the outlet pipe 3. In this way, the condensed liquid-phase refrigerant flows from top to bottom without resisting gravity, making it difficult for the refrigerant to stagnate.

[0110] By reversing the flow of refrigerant in the refrigerant circuit R, the functions of the inlet pipe and outlet pipe of the outdoor heat exchanger 300 are also swapped. As a result, the outlet pipe is located on the downwind side, and the inlet pipe is located on the upwind side.

[0111] The flow rate control unit 400 controls the amount of refrigerant introduced into the indoor heat exchanger 200, for example, by controlling the valve opening of the expansion valve 302 and the operation of the compressor 301, thereby controlling the degree of subcooling of the refrigerant discharged from the discharge pipe 4 of the indoor heat exchanger 200 to a predetermined value or higher. The flow rate control unit 400 controls the flow rate of the refrigerant so that the refrigerant flowing through each heat transfer tube 10 has a degree of subcooling (so that the refrigerant temperature is below the saturation temperature) in a region (hereinafter referred to as the supercooling region SC) set on one end side of the heat exchange unit 1G to which the discharge pipe 4 is connected. The degree of subcooling is set to, for example, 5 to 10 degrees.

[0112] 14(b) is a graph showing the temperature change of the refrigerant and air flowing through the lower stage (heat exchangers 1I and 1G) of the indoor heat exchanger 200 used as a condenser in this way. By providing the discharge pipe 3 on the upwind side, a large temperature difference between the refrigerant and air in the discharge pipe 3 is ensured.

[0113] During heating operation, there is little need to ensure a degree of superheat at the outlet of the evaporator in the outdoor heat exchanger 300. Therefore, the flow rate control unit 400 controls the amount of refrigerant introduced into the outdoor heat exchanger 300, for example, by controlling the operation of the compressor 301, so that the refrigerant discharged from the discharge pipe of the outdoor heat exchanger 300 does not become superheated (so that the refrigerant temperature does not exceed the saturation temperature).

[0114] Even when functioning as a condenser in this way, in the case of the indoor heat exchanger 200, by providing the discharge pipe 3 on the upwind side, the temperature difference between the refrigerant and the air near the discharge pipe 3 can be made as large as possible, and even when the refrigerant is made to have a large degree of subcooling in the discharge pipe 3, a sufficient temperature difference between the refrigerant and the air can be ensured to guarantee heat exchange efficiency.

[0115] In the outdoor heat exchanger 300, a discharge pipe that does not create superheat is provided on the upwind side, so that a sufficient temperature difference between the refrigerant and the air can be ensured throughout the entire refrigerant flow path within the outdoor heat exchanger 300.

[0116] In this way, the air conditioner AC of the second embodiment uses the indoor heat exchanger 200 and the outdoor heat exchanger 300, which have different connection modes for the exhaust pipe and the inlet pipe, to ensure the heat exchange efficiency of each heat exchanger in both heating and cooling operation, and as a result, the heat exchange efficiency of the entire refrigerant circuit can be maintained at a high level.

[0117] [Modification of the second embodiment] The number of rows of the heat exchange unit group constituting the indoor heat exchanger 200 is not limited to two, but may be any number of rows. A heat exchange unit group is formed by grouping together multiple heat exchange units lined up in the vertical direction in the same row in the front-to-back direction of the indoor heat exchanger 200.

[0118] Even when three or more rows of heat exchanger units are arranged, it is desirable that the inlet pipe and the outlet pipe be connected to the same heat exchanger unit, but this is not limited to this. The inlet pipe and the outlet pipe may be connected to the heat exchanger unit unit arranged upwind of the heat exchanger unit unit arranged furthest downwind. The inlet pipe and the outlet pipe may be connected to the heat exchanger unit unit arranged furthest upwind.

[0119] Furthermore, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0120] 100...heat exchanger 1...Heat exchange section 10 Heat transfer tube 11...One end 12...Other end 2. Folded section 2X...Top and bottom folds 20X....upper and lower folded flow path 2Y...Horizontal folding section 20Y...Horizontal folding channel 3...Introduction tube 4...Discharge pipe 5 ... shunt 6 Dummy heat transfer tube L Refrigerant flow path 14. Windward heat exchanger group 15. Downwind heat exchanger group AC ···Air conditioner R...Refrigerant circuit 200...Indoor heat exchanger 300...Outdoor heat exchanger 301 Compressor 302 Expansion valve 400···Flow control section SH...Superheating degree secured area SC...Supercooling degree guaranteed area

Claims

1. a first heat exchange unit having a plurality of first heat transfer tubes arranged in a vertical direction and having the same refrigerant flow direction; a second heat exchange unit that is arranged adjacent to the first heat exchange unit in the vertical direction and has a plurality of second heat transfer tubes that are arranged side by side in the vertical direction and whose refrigerant flow directions are the same as each other and opposite to each other from the first heat transfer tubes; an upper and lower turning portion that connects downstream ends of the plurality of first heat transfer tubes and upstream ends of the plurality of second heat transfer tubes and turns the refrigerant that has flowed through the first heat transfer tubes in the upper and lower direction to flow into the second heat transfer tubes, the upper and lower folded portions have upper and lower folded flow paths that individually connect the first heat transfer tubes and the second heat transfer tubes.

2. the number of the first heat transfer tubes and the number of the second heat transfer tubes are the same; The heat exchanger according to claim 1 , wherein the upper and lower folded portion has a plurality of the upper and lower folded flow paths that individually connect the plurality of first heat transfer tubes and the plurality of second heat transfer tubes.

3. The heat exchanger according to claim 2 , wherein each of the upper and lower folded flow paths connects the first heat transfer tube and the second heat transfer tube that are arranged at the same position in each of the heat exchange sections.

4. 2. The heat exchanger according to claim 1, wherein the lengths of the upper and lower turn-back flow paths are substantially the same.

5. a third heat exchange unit that is arranged adjacent to the second heat exchange unit in the horizontal direction and has a plurality of third heat transfer tubes that are arranged side by side in the vertical direction and whose refrigerant flow directions are the same as each other but opposite to each other from the second heat transfer tubes; a horizontal turning portion that connects a downstream end of the second heat transfer tube and an upstream end of the third heat transfer tube, and turns the refrigerant that has flowed through the second heat transfer tube in the horizontal direction to flow into the third heat transfer tube, The heat exchanger according to claim 1 , wherein the horizontally folded portion has horizontally folded flow passages that individually connect the second heat transfer tubes and the third heat transfer tubes.

6. the heat exchanger is an evaporator; The heat exchanger according to claim 5 , wherein the first heat exchange section and the second heat exchange section are arranged on the windward side, and the third heat exchange section is arranged on the leeward side.

7. The heat exchanger according to claim 1 , further comprising one or more dummy heat transfer tubes, through which no refrigerant flows, arranged between the first heat exchange section and the second heat exchange section.

8. A heat exchange system configured by stacking a plurality of heat exchangers according to claim 1 in the vertical direction so that they are plane-symmetrical to each other when viewed horizontally.

9. a leeward heat exchange unit group including a plurality of leeward heat exchange units, each including the first heat exchange unit and the second heat exchange unit, arranged in the vertical direction; a windward-side heat exchange unit group including a plurality of windward-side heat exchange units arranged in the vertical direction and arranged on the windward side of the downwind-side heat exchange unit; a turn-back portion including the upper and lower turn-back portions, connecting the upwind-side heat exchange portion and the downwind-side heat exchange portion to form a continuous refrigerant flow path together with the turn-back portions; an introduction pipe connected to one of the plurality of upwind-side heat exchange units constituting the upwind-side heat exchange unit group, and introducing a refrigerant into one end of the refrigerant flow path; a discharge pipe connected to another one of the plurality of upwind-side heat exchange units constituting the upwind-side heat exchange unit group, and discharging the refrigerant from the other end of the refrigerant flow path; The heat exchanger of claim 1 further comprising:

10. An air conditioner comprising the heat exchanger according to claim 1.

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