HEAT EXCHANGER AND AIR-CONDITIONING APPARATUS

Abstract

A heat exchanger includes heat transfer tubes, each having through holes, and including coupling units being configured to directly couple the through holes of adjacent heat transfer tubes from among the heat transfer tubes, or header pipes being inserted into the plurality of through holes, and being configured to couple the through holes of adjacent heat transfer tubes from among the heat transfer tubes, the coupling units or the header pipes constitute a plurality of header units extending in a first direction, allowing refrigerant communication between inner spaces of the heat transfer tubes, and forming a refrigerant inlet/outlet of a heat transfer tube group constituted of the heat transfer tubes, and header units are provided at a position dividing the plurality of heat transfer tubes into upper and lower portions in a gravity direction.

Description

TECHNICAL FIELD

The present disclosure relates to a heat exchanger and to an air-conditioning apparatus that includes this heat exchanger.

BACKGROUND ART

In the related art, there have been heat exchangers in which heat transfer tubes are vertically installed, the heat exchanger including header units and the plurality of heat transfer tubes, the plurality of heat transfer tubes being connected to the header units, and being formed to extend in the up-down direction (see Patent Literature 1, for example).

CITATION LIST

Patent Literature

• • Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2018-96638

SUMMARY OF INVENTION

Technical Problem

In a heat exchanger in which heat transfer tubes are vertically installed as in the heat exchanger of Patent Literature 1, in the case where the heat transfer tubes have a long length in the vertical direction, there may be cases where, when refrigerant flows into the heat exchanger from the lower portion of the heat exchanger during a condensation operation, the refrigerant fails to rise to the upper portion of the heat transfer tubes by being overwhelmed by the head difference (potential energy), so that liquid stagnation occurs.

The present disclosure has been made to solve the above-mentioned problem, and it is an object of the present disclosure to provide a heat exchanger and an air-conditioning apparatus that reduce the head difference to reduce liquid stagnation.

Solution to Problem

A heat exchanger according to one embodiment of the present disclosure includes a plurality of heat transfer tubes arranged in a first direction, each of the plurality of heat transfer tubes extending in a second direction intersecting the first direction, each of the plurality of heat transfer tubes having both end portions in the second direction sealed, the plurality of heat transfer tubes being configured to allow refrigerant to flow therethrough. Each of the plurality of heat transfer tubes has a plurality of through holes formed at positions inward of the both end portions, the plurality of through holes allowing an outside and an inner space of each of the plurality of heat transfer tubes to be in communication. The plurality of heat transfer tubes include a plurality of coupling units or a plurality of header pipes, the plurality of coupling units being configured to directly couple the plurality of through holes of adjacent heat transfer tubes from among the plurality of heat transfer tubes, the plurality of header pipes being inserted into the plurality of through holes, and being configured to couple the plurality of through holes of adjacent heat transfer tubes from among the plurality of heat transfer tubes. The plurality of coupling units or the plurality of header pipes constitute a plurality of header units formed to extend in the first direction, each of the plurality of header units allowing refrigerant communication between the inner spaces of the plurality of heat transfer tubes, and forming a refrigerant inlet/outlet of a heat transfer tube group constituted of the plurality of heat transfer tubes. The plurality of header units are provided at a position that divides the plurality of heat transfer tubes into an upper portion and a lower portion in a gravity direction.

An air-conditioning apparatus according to another embodiment of the present disclosure includes the above-mentioned heat exchanger.

Advantageous Effects of Invention

The heat exchanger and the air-conditioning apparatus according to the embodiment of the present disclosure include the plurality of header units formed by coupling the plurality of through holes with the coupling units or with the header pipes, and the plurality of header units are provided at the position that divides the plurality of heat transfer tubes into the upper portion and the lower portion in the gravity direction. Compared with the case where the plurality of header units are not provided at the position that divides the plurality of heat transfer tubes into the upper portion and the lower portion in the gravity direction, the heat exchanger and the air-conditioning apparatus can shorten the distance that refrigerant rises in the heat transfer tubes. Compared with the case where the plurality of header units are not provided at the position that divides the plurality of heat transfer tubes into the upper portion and the lower portion in the gravity direction, the heat exchanger and the air-conditioning apparatus can shorten the distance that refrigerant rises and hence, the head difference can be reduced, and thus liquid stagnation can be reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing the schematic configuration of a heat exchanger according to Embodiment 1.

FIG. 2 is a longitudinal sectional view of the heat exchanger according to Embodiment 1.

FIG. 3 is a diagram of a heat transfer tube of the heat exchanger according to Embodiment 1, as viewed in a first direction.

FIG. 4 is a conceptual sectional view, taken along line A-A, of the heat transfer tube shown in FIG. 3 of the heat exchanger according to Embodiment 1, as viewed in the direction of arrows.

FIG. 5 is a longitudinal sectional view of a modification of the heat exchanger according to Embodiment 1.

FIG. 6 is a refrigerant circuit diagram of an air-conditioning apparatus in which the heat exchanger of Embodiment 1 is mounted, for the case of a cooling operation.

FIG. 7 is a perspective view showing a heat transfer tube of a heat exchanger according to Embodiment 2.

FIG. 8 is a conceptual sectional view, taken along line A-A, of the heat transfer tube shown in FIG. 3 of the heat exchanger according to Embodiment 2, as viewed in the direction of arrows.

FIG. 9 is a perspective view showing a portion of the inner surface of a heat transfer tube of a heat exchanger according to Embodiment 3.

FIG. 10 is a conceptual view of a heat exchanger according to Embodiment 4, as viewed in the first direction.

FIG. 11 is a conceptual view of a modification of the heat exchanger according to Embodiment 4, as viewed in the first direction.

FIG. 12 is a conceptual view of a heat exchanger according to a comparative example, as viewed in the first direction.

FIG. 13 is a conceptual view of a heat exchanger according to Embodiment 5, as viewed in the first direction.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a heat exchanger according to Embodiment 1 and an air-conditioning apparatus that includes this heat exchanger will be described with reference to, for example, the drawings. In the drawings including FIG. 1, the relative size relationships, shapes, and other aspects of respective constitutional components may differ from those of actual constitutional components. In the following drawings, components given the same reference symbols are same or corresponding components, and the same applies throughout the entire specification. Although terms indicating directions (“up”, “down”, “right”, “left”, “front”, and “rear”, for example) are suitably used to facilitate the understanding, these terms are used for convenience of description and are not intended to limit the arrangement or the orientation of the apparatus or a component. Herein, the positional relationships between the respective constitutional components, the extension directions of the respective constitutional components, and the arrangement directions of the respective constitutional components refer to, in principle, directions when the heat exchanger is installed in a usable state.

Embodiment 1

[Configuration of Heat Exchanger 100]

FIG. 1 is a perspective view showing the schematic configuration of a heat exchanger 100 according to Embodiment 1. Outline arrows shown in FIG. 1 show an example of a flow direction of refrigerant. The configuration of the heat exchanger 100 will be described with reference to FIG. 1. The direction of refrigerant shown below by the outline arrows is merely an example, and there may be cases where the flow direction of refrigerant is opposite to the direction shown in the drawing depending on whether the heat exchanger 100 serves as an evaporator or a condenser. In FIG. 1, a partition unit 70 provided in each heat transfer tube 10 is shown by a broken line.

The heat exchanger 100 is equipment that exchanges heat between refrigerant flowing through the heat exchanger 100 and a fluid flowing outside the heat exchanger 100. In the case of an air-conditioning apparatus, the heat exchanger 100 exchanges heat between refrigerant flowing through the heat exchanger 100 and air flowing outside the heat exchanger 100. The heat exchanger 100 is connected to another heat exchanger, a compressor, and other components via refrigerant pipes, and constitutes one of various elements that constitute a refrigerant circuit.

FIG. 2 is a longitudinal sectional view of the heat exchanger 100 according to Embodiment 1. FIG. 3 is a diagram of the heat transfer tube 10 of the heat exchanger 100 according to Embodiment 1, as viewed in a first direction D1. FIG. 4 is a conceptual sectional view, taken along line A-A, of the heat transfer tube 10 shown in FIG. 3 of the heat exchanger 100 according to Embodiment 1, as viewed in the direction of arrows. The sectional view shown in FIG. 2 shows the cross section of the heat exchanger 100 taken along a plane extending along the first direction D1 and a second direction D2. FIG. 2 shows a portion of the heat exchanger 100. In FIG. 3, the partition unit 70 provided in each heat transfer tube 10 is shown by the broken line. Hereinafter, the structure of the heat exchanger 100 will be described in detail with reference to FIG. 1 to FIG. 4.

The heat exchanger 100 includes the plurality of heat transfer tubes 10 arranged in the first direction D1, each of the plurality of heat transfer tubes 10 extending in the second direction D2, which intersects the first direction D1, each of the plurality of heat transfer tubes 10 having both end portions in the second direction D2 sealed, the plurality of heat transfer tubes 10 being configured to allow refrigerant to flow therethrough in the second direction D2.

(Heat Transfer Tube 10)

As shown in FIG. 1, the heat exchanger 100 includes the plurality of heat transfer tubes 10 that are arranged in the first direction D1, and that are coupled to each other. Each heat transfer tube 10 is, for example, a flat tube, extends in an extension direction of a tube axis Ax (hereinafter also referred to as “tube axial direction”), and has a flat shape elongated in one direction in cross section perpendicular to the tube axis Ax. Although each heat transfer tube 10 is preferably a flat tube, the heat transfer tube 10 is not limited to the flat tube.

In the description made hereinafter, the first direction D1 in which the plurality of heat transfer tubes 10 are arranged may be referred to as “arrangement direction”, the tube axial direction of the heat transfer tube 10 may be referred to as “second direction D2” or “the longitudinal direction of the heat transfer tube 10”, and the longitudinal direction in cross section of the heat transfer tube 10 may be referred to as “third direction D3” or “the shorthand direction of the heat transfer tube 10”. The third direction D3 is a direction orthogonal to the first direction D1 and to the second direction D2.

In the description made hereinafter, it is defined that, as shown in FIG. 1, the heat exchanger 100 is installed such that the arrangement direction of the heat transfer tubes 10 (the first direction D1) extends in the left-right direction. It is also defined that each heat transfer tube 10 is disposed such that the tube axis Ax of the heat transfer tube 10 extends in the up-down direction orthogonal to the arrangement direction (the first direction D1), and the shorthand direction of the heat transfer tube 10 (the third direction D3) extends in the front-rear direction orthogonal to the tube axial direction and to the arrangement direction.

The arrangement of the heat exchanger 100, and an angle between the arrangement direction of the heat transfer tubes 10 (the first direction D1) and the tube axial direction of each heat transfer tube 10 (the second direction D2) in the heat exchanger 100 are not limited to the above-mentioned arrangement and angles. For example, the heat exchanger 100 may be disposed in an inclined manner such that the tube axial direction of each heat transfer tube 10 extends in a direction at an angle to the up-down direction. Alternatively, the heat exchanger 100 may be configured such that, when the heat exchanger 100 is installed with the arrangement direction of the heat transfer tubes 10 (the first direction D1) extending in the left-right direction, the tube axial direction of each heat transfer tube 10 extends in a direction at an angle to the up-down direction.

Gaps that form flow passages P2 for air are formed between tube walls 11 of the heat transfer tubes 10 adjacent to each other in the arrangement direction of the heat transfer tubes 10 (the first direction D1), and air flows through each gap along the shorthand direction of the heat transfer tube 10 (the third direction D3) in the heat exchanger 100. A fluid that flows through the heat transfer tubes 10 is refrigerant. A heat transfer passage P1a through which refrigerant flows is provided in each heat transfer tube 10. Instead of refrigerant, other fluids, such as water or brine, may be used as the fluid that flows through the heat transfer tubes 10.

The end portions of each heat transfer tube 10 on both sides in the longitudinal direction (the second direction D2) are sealed. To be more specific, the heat exchanger 100 includes tube sealing units 20 that close respective opening ends 10e of the heat transfer tubes 10 on both sides in the longitudinal direction (the second direction D2). In the example shown in FIG. 2, the tube sealing units 20 are provided for each heat transfer tube 10 at two positions, on the upper side and the lower side of the flat tube. The tube sealing units 20 are joined to, for example, the opening ends 10e of the heat transfer tubes 10 by joining means, such as brazing or an adhesive agent.

As shown in FIG. 2 to FIG. 4, each of the plurality of heat transfer tubes 10 includes the tube wall 11 in which the heat transfer passage P1a is provided in the inner space, refrigerant flowing through the heat transfer passage P1a. The heat transfer tube 10 has a tube structure in which an inner space, through which refrigerant flows, is held along the longitudinal direction of the heat transfer tube 10 (the second direction D2), that is, from the upper end to the lower end of the tube wall 11.

The tube wall 11 of the heat transfer tube 10 includes a tube side wall part 10a and a tube side wall part 10b that face each other in the first direction D1, and that have a substantially flat plate shape. The tube wall 11 of the heat transfer tube 10 also includes a connecting wall part 10c and a connecting wall part 10d that have a curved surface shape, and that connect the tube side wall part 10a and the tube side wall part 10b together at the respective end portions of the tube side wall part 10a and the tube side wall part 10b on both sides in the third direction D3. In the description made hereinafter, the tube side wall part 10a and the tube side wall part 10b may be described as “the tube side wall part 10a and the like”.

Each of the tube side wall part 10a and the tube side wall part 10b has a rectangular shape in which the long sides extend in the longitudinal direction of the heat transfer tube 10 (the second direction D2), and the short sides extend in the shorthand direction of the heat transfer tube 10 (the third direction D3). Although each of the tube side wall part 10a and the tube side wall part 10b has a flat plate shape, “flat plate shape” in the present application is not necessarily a perfectly flat surface, and it is sufficient that “flat plate shape” be a structure that appears as a whole to have a flat surface. For example, each of the tube side wall part 10a and the tube side wall part 10b may have recesses, protrusions, or corrugations at a portion of a flat surface region thereof. In FIG. 2, the left wall part of each tube wall 11 is the tube side wall part 10a, and the right wall part of each tube wall 11 is the tube side wall part 10b. In the case where each heat transfer tube 10 is a circular tube, the tube wall 11 is formed to have a cylindrical shape.

As shown in FIG. 2 and FIG. 3, each of the plurality of heat transfer tubes 10 has a plurality of through holes 30 that are formed at positions inward of both end portions of the heat transfer tube 10 in the second direction D2, the plurality of through holes 30 allowing the outside and the inner space of each of the plurality of heat transfer tubes 10 to be in communication.

As shown in FIG. 2 and FIG. 3, each of the tube side wall part 10a and the tube side wall part 10b has the through holes 30. The tube side wall part 10a on the left side has through holes 30a penetrating through the tube side wall part 10a in the first direction D1, and the tube side wall part 10b on the right side has through holes 30b penetrating through the tube side wall part 10b in the first direction D1.

The through holes 30a and the through holes 30b are through holes that constitute a first header unit 51 and a second header unit 52, which will be described later. The through holes 30a and the through holes 30b are formed at positions that face each other in the first direction D1. The through hole 30 is used as a general term for the through hole 30a and the through hole 30b. The through holes 30 are through holes that constitute header units 50 described later.

As shown in FIG. 2, the adjacent heat transfer tubes 10 include coupling units 12 for coupling the tube walls 11 of the heat transfer tubes 10 to each other. The adjacent heat transfer tubes 10 include the coupling units 12 that connect the tube walls 11 to each other, and that allow the heat transfer passages P1a in the tube walls 11 to be in communication. Each heat transfer tube 10 includes the tube wall 11, coupling protrusion units 12a, and coupling protrusion units 12b, the coupling protrusion units 12a and the coupling protrusion units 12b forming the coupling units 12 extending outward from the tube wall 11 in the first direction D1.

Each coupling unit 12 of the adjacent heat transfer tubes 10 has a cylindrical shape in which a hollow part Sg extends in the first direction D1. The coupling unit 12 is formed by combining the coupling protrusion unit 12a and the coupling protrusion unit 12b together. In the example shown in FIG. 2, the coupling unit 12 is formed by inserting the coupling protrusion unit 12b into the coupling protrusion unit 12a. The coupling protrusion unit 12a and the coupling protrusion unit 12b, which form the coupling unit 12, have a configuration in which, for example, the coupling protrusion unit 12b is fitted into the coupling protrusion unit 12a.

The coupling unit 12 is constituted of the coupling protrusion unit 12a and the coupling protrusion unit 12b that are formed on at least one of the tube side wall part 10a and the like, facing each other, of the adjacent heat transfer tubes 10, and that protrude from the peripheral edge portions of the through holes 30 in the first direction D1.

The coupling unit 12 need not be configured such that the coupling protrusion unit 12b is fitted into the coupling protrusion unit 12a. For example, the coupling unit 12 may be configured such that the coupling protrusion unit 12a and the coupling protrusion unit 12b are joined together by joining means, such as brazing or an adhesive agent.

The coupling unit 12 is constituted of the coupling protrusion unit 12a or the coupling protrusion unit 12b provided to at least one of the tube side wall part 10a or the tube side wall part 10b of the adjacent heat transfer tubes 10, the tube side wall part 10a and the tube side wall part 10b facing each other. The coupling protrusion unit 12a extends from the peripheral edge portion of the through hole 30a toward the tube side wall part 10b that the tube side wall part 10a faces. The coupling protrusion unit 12b extends from the peripheral edge portion of the through hole 30b toward the tube side wall part 10a that the tube side wall part 10b faces.

In FIG. 2, the coupling unit 12 is constituted of the coupling protrusion unit 12a and the coupling protrusion unit 12b that have a cylindrical shape, and that are respectively formed on the tube side wall part 10a and the tube side wall part 10b of the adjacent heat transfer tubes 10, the tube side wall part 10a and the tube side wall part 10b facing each other. The through hole 30a and the coupling protrusion unit 12a, or the through hole 30b and the coupling protrusion unit 12b, can be formed such that, for example, a hole is formed in a flat plate portion of the heat transfer tube 10, and burring is performed to deform and raise the flat plate portion at the peripheral edge of the hole into a cylindrical shape.

As shown in FIG. 2, the coupling unit 12 connects the through hole 30a provided to the tube side wall part 10a and the through hole 30b provided to the tube side wall part 10b together by the hollow part Sg, thus allowing the inner spaces of adjacent tube walls 11 to be in communication. The coupling unit 12 also has a function of providing a partition between the hollow part Sg in the coupling unit 12 and the flow passage P2 for air, the flow passage P2 being a space outside the coupling unit 12.

As shown in FIG. 2 and FIG. 3, the through holes 30 and the coupling units 12 are formed at positions inward of the opening ends 10e of the heat transfer tube 10 on both sides in the longitudinal direction (the second direction D2). To be more specific, in the heat exchanger 100 disposed as shown in FIG. 1, the through holes 30, the coupling protrusion units 12a, and the coupling protrusion units 12b of each heat transfer tube 10 are formed at positions lower than the opening end 10e of the heat transfer tube 10 on the upper side, and higher than the opening end 10e of the heat transfer tube 10 on the lower side.

The through holes 30 and the coupling units 12 are formed at a position that divides the plurality of heat transfer tubes 10 into an upper portion and a lower portion in the gravity direction. The through holes 30 and the coupling units 12 are provided at a center portion 17 of the plurality of heat transfer tubes 10 in the second direction D2. The center portion 17 includes not only an exact center portion of the heat transfer tubes 10 in the second direction D2, but also portions in the vicinity of the center portion. Two through holes 30 are formed to be arranged in the third direction D3 of the heat transfer tube 10. Two coupling units 12 are also formed to be arranged in the third direction D3 of the heat transfer tube 10.

The heat transfer tube 10 may be manufactured such that, for example, the through holes 30, the coupling protrusion units 12a, and the coupling protrusion units 12b are formed in advance on a precursor member for the heat transfer tube 10, and this member is then shaped by roll forming. The coupling protrusion units 12a and the coupling protrusion units 12b may be formed by raising the peripheral edge portions of the holes in forming the through holes 30 in a precursor member for the heat transfer tube 10. For example, a metal material having high thermal conductivity, such as aluminum, copper, or brass, is used for forming the heat transfer tube 10.

Each of the plurality of heat transfer tubes 10 includes the partition unit 70 disposed in the inner space of the tube wall 11, extending in the second direction D2, and configured to divide the inner space in the third direction D3 orthogonal to the first direction D1 and to the second direction D2. Both ends of the partition unit 70 in the second direction D2 are located at positions inward of the ends of the heat transfer passage P1a of the heat transfer tube 10 on both sides in the second direction D2. An upper end 70a of the partition unit 70 is provided at a position lower than the opening end 10e of the heat transfer tube 10 on the upper side (see FIG. 2), and a lower end 70b of the partition unit 70 is provided at a position higher than the opening end 10e of the heat transfer tube 10 on the lower side (see FIG. 2).

The partition unit 70 is a plate-shaped or rod-shaped member that extends in the first direction D1 and the second direction D2 in the inner space of the heat transfer tube 10. The partition unit 70 is provided to connect the tube side wall part 10a and the tube side wall part 10b to each other. The partition unit 70 is provided to extend between the tube side wall part 10a and the tube side wall part 10b. The partition unit 70 is a member that partitions the inner space of the heat transfer tube 10 in the third direction D3, except for both end portions of the heat transfer tube 10 in the second direction D2.

The partition unit 70 is provided in the inner space of the heat transfer tube 10 at, for example, the center portion in the third direction D3. The installation position of the partition unit 70 is not limited to such a portion, and may be provided at a position offset in either direction in the third direction D3.

A refrigerant flow passage in the heat exchanger 100 includes the heat transfer passages P1a each of which is provided in the tube wall 11 of each heat transfer tube 10, and each of which extends in the longitudinal direction of the heat transfer tube 10 (the second direction D2). The refrigerant flow passage in the heat exchanger 100 also includes a header flow passage P1b that extends in the arrangement direction of the plurality of heat transfer tubes 10 (the first direction D1) to allow the heat transfer passages P1a of the plurality of heat transfer tubes 10 to be in communication. The refrigerant flow passage in the heat exchanger 100 also includes a header flow passage P1c that extends in the arrangement direction of the plurality of heat transfer tubes 10 (the first direction D1) to allow the heat transfer passages P1a of the plurality of heat transfer tubes 10 to be in communication.

Each heat transfer passage P1a is partitioned into a first flow passage P1a1 and a second flow passage P1a2 by the partition unit 70. The first flow passage P1a1 is a flow passage that extends in the second direction D2 of the heat transfer tube 10, refrigerant that flows into the first flow passage P1a1 from the first header unit 51 described later separately flowing toward the upper and lower ends of the heat transfer tube 10 from the center portion 17 of the heat transfer tube 10. The second flow passage P1a2 is a flow passage that extends in the second direction D2 of the heat transfer tube 10, refrigerant that flows into the second flow passage P1a2 from the first flow passage P1a1 flowing toward the center portion 17 from the upper and lower ends of the heat transfer tube 10, merging at the center portion 17, and flowing toward the second header unit 52.

The first flow passage P1a1 and the second flow passage P1a2 are in communication at both the upper and lower end portions of the heat transfer tube 10. Therefore, the heat transfer passage P1a for refrigerant has a substantially O shape.

The refrigerant flow passage in the heat exchanger 100 includes the plurality of heat transfer passages P1a, the header flow passage P1b, and the header flow passage P1c (see FIG. 3), the header flow passage P1b and the header flow passage P1c being provided at the center portion 17 of the heat exchanger 100 in such a way as to be arranged in the front-rear direction. The header flow passage P1b is constituted of, for example, the hollow parts Sg of the plurality of coupling units 12 that are provided on the front side at the center portion 17 of the heat exchanger 100. The header flow passage P1c is constituted of, for example, the hollow parts (not shown in the drawing) of the plurality of coupling units 12 that are provided on the rear side at the center portion 17 of the heat exchanger 100.

Each heat transfer passage P1a is in communication with the header flow passage P1b and the header flow passage P1c at the center portion 17 of the heat transfer passage P1a in the longitudinal direction of the heat transfer tube 10 (the second direction D2). The header flow passage P1b and the header flow passage P1c are in communication with the plurality of heat transfer passages P1a. For example, the through holes 30a, the through holes 30b, and the hollow parts Sg of the coupling units 12 described above constitute the header flow passage P1b and the header flow passage P1c, and refrigerant flows through the hollow parts Sg.

In the heat exchanger 100, each coupling unit 12 is formed of portions of the heat transfer tubes 10 and, of the header flow passage P1b and the header flow passage P1c, portions disposed between the tube walls 11 of the heat transfer tubes 10 are the hollow parts Sg formed in the coupling units 12. Accordingly, in the heat exchanger 100, the header flow passage P1b and the header flow passage P1c are formed in the heat transfer tubes 10, being heat exchange members, and hence, it is unnecessary to provide a header unit outside the plurality of heat transfer tubes 10.

The plurality of heat transfer tubes 10 include a plurality of header units 50 formed by coupling the plurality of through holes 30 of the adjacent heat transfer tubes 10 from among the plurality of heat transfer tubes 10. Each header unit 50 is formed to extend in the horizontal direction, for example. The header unit 50 is formed to have a smaller width than the plurality of heat transfer tubes 10 in the third direction D3 orthogonal to the first direction D1 and to the second direction D2. As shown in FIG. 1, the header units 50 allow refrigerant communication between the inner spaces of the plurality of heat transfer tubes 10, and form a refrigerant inlet/outlet 51a and a refrigerant inlet/outlet 52a of a heat transfer tube group 15 constituted of the plurality of heat transfer tubes 10. The end portions of the header units 50 on the side opposite to the inlet/outlet 51a and the inlet/outlet 52a are closed, for example, by the tube wall 11.

The header unit 50 serves as a distribution mechanism that distributes refrigerant flowing into the heat transfer tube group 15 to the plurality of heat transfer tubes 10. When refrigerant flows out from the heat transfer tube group 15, the header unit 50 serves as a merge mechanism at which the refrigerant flowing out from the plurality of heat transfer tubes 10 merges.

The plurality of header units 50 include at least the first header unit 51 and the second header unit 52. The header unit 50 is used as a general term for the first header unit 51 and the second header unit 52. As shown in FIG. 1 and FIG. 2, the plurality of header units 50 include the first header unit 51 and the second header unit 52, the first header unit 51 being provided on one end portion side of the heat transfer tubes 10 in the third direction D3, the second header unit 52 being provided on the other end portion side of the heat transfer tubes 10 in the third direction D3. The header units 50 are provided at a position inward of the end portions of the heat transfer tubes 10 in the second direction D2. The positions of the first header unit 51 and the second header unit 52 in the third direction D3 may be opposite to the positions illustrated in the drawing.

The plurality of header units 50 are formed at the position that divides the plurality of heat transfer tubes 10 into the upper portion and the lower portion in the gravity direction. The plurality of header units 50 are provided at the center portion 17 of the plurality of heat transfer tubes 10 in the second direction D2. The first header unit 51 and the second header unit 52 are formed to be arranged in the third direction D3 of the heat transfer tube 10.

In the heat exchanger 100 of Embodiment 1, in the case where the heat exchanger 100 serves as one of either a condenser or an evaporator, the plurality of header units 50 include the first header unit 51 and the second header unit 52, the first header unit 51 forming a refrigerant inflow port, the second header unit 52 forming a refrigerant outflow port. The first header unit 51 and the second header unit 52 are provided on both sides of the partition unit 70 in the third direction D3 with the partition unit 70 interposed therebetween.

As described above, the plurality of heat transfer tubes 10 include the plurality of coupling units 12 that directly couple the plurality of through holes 30 of the adjacent heat transfer tubes 10 from among the plurality of heat transfer tubes 10, and each of the plurality of header units 50 is constituted of the plurality of coupling units 12. That is, the plurality of coupling units 12 form the plurality of header units 50 formed to extend in the first direction D1. The plurality of coupling units 12 constitute the plurality of header units 50 each of which allows refrigerant communication between the inner spaces of the plurality of heat transfer tubes 10, and each of which forms the refrigerant inlet/outlet of the heat transfer tube group 15 constituted of the plurality of heat transfer tubes 10. In the heat exchanger 100, the coupling units 12 provided to the through holes 30 directly couples the through holes 30 to each other.

[Modification of the Heat Exchanger 100]

FIG. 5 is a longitudinal sectional view of a modification of the heat exchanger 100 according to Embodiment 1. FIG. 5 shows a portion of the heat exchanger 100. The modification of the heat exchanger 100 will be described with reference to FIG. 5.

For forming header units 50, the heat exchanger 100 may include header pipes 80, instead of the coupling units 12. That is, for coupling the through holes 30 to each other, the heat exchanger 100 may use the header pipes 80 instead of the coupling units 12. In the heat exchanger 100, the through holes 30 may be coupled to each other using the header pipes 80, that is, using separate members from the heat transfer tubes 10.

The plurality of heat transfer tubes 10 include the plurality of header pipes 80 that are inserted into the plurality of through holes 30 to couple the plurality of through holes 30 of the adjacent heat transfer tubes 10 from among the plurality of heat transfer tubes 10. Each of the plurality of header units 50 is formed of the header pipe 80 that is inserted into the through holes 30. The header pipe 80 has a plurality of holes 82 that are in communication with the inner spaces of the plurality of heat transfer tubes 10.

Each of the plurality of heat transfer tubes 10 includes a tube wall 11 in which a heat transfer passage P1a is provided in the inner space, fluid flowing through the heat transfer passage P1a. The tube wall 11 includes a tube side wall part 10a and the like that face each other in the first direction D1, and the tube side wall part 10a and the like have the through holes 30 into which the header pipes 80 are inserted. In the heat exchanger 100, the through holes 30 are indirectly coupled to each other by the header pipes 80.

As described above, each header pipe 80 penetrates through the plurality of heat transfer tubes 10 in the first direction D1, and refrigerant flows through the header pipe 80. The header pipe 80 is, for example, a circular tube having a cylindrical cross-sectional shape. The header pipe 80 is not limited to a circular tube and may be a tube having other cross-sectional shapes different from a cylindrical cross-sectional shape.

The header flow passage P1b or the header flow passage P1c is formed in each header pipe 80 or the coupling units 12. For example, the header pipe 80 or the coupling units 12 that forms the first header unit 51 forms the header flow passage P1b, and the header pipe 80 or the coupling units 12 that forms the second header unit 52 forms the header flow passage P1c.

The plurality of header units 50 are formed to extend in the first direction D1, each of the plurality of header units 50 allowing refrigerant communication between the inner spaces of the plurality of heat transfer tubes 10, and forming the refrigerant inlet/outlet of the heat transfer tube group 15 constituted of the plurality of heat transfer tubes 10.

Next, an example of the action of the heat exchanger 100 will be described with reference to FIG. 1 and FIG. 2. As shown in FIG. 1, refrigerant that flows into the heat transfer tube group 15 from the first header unit 51 flows through the heat transfer tube group 15, and then flows out from the second header unit 52. To be more specific, as shown by outline arrows in FIG. 1, refrigerant flows into the heat exchanger 100 from the refrigerant inlet/outlet 51a of the first header unit 51. As shown in FIG. 2, in the heat exchanger 100, the refrigerant first flows into and flows through the header flow passage P1b of the first header unit 51, which penetrates through, in the left-right direction, the center portion 17 of the plurality of heat transfer tubes 10. In this process, the refrigerant is distributed to and flows into the heat transfer passages P1a provided in the tube walls 11 of the plurality of respective heat transfer tubes 10.

As shown in FIG. 3, in each heat transfer tube 10, the refrigerant that flows into each heat transfer passage P1a from the first header unit 51 is branched and flows toward the upper portion and the lower portion of the first flow passage P1a1, flows into the second flow passage P1a2 from the first flow passage P1a1, merges in the second flow passage P1a2, and then flows out from the second header unit 52. As the refrigerant flows through the heat transfer tube 10, the refrigerant exchanges heat, via the tube wall 11, with air flowing through the gaps formed between the tube walls 11 of the heat transfer tubes 10 (that is, the flow passage P2 for air). The refrigerant flows into the header flow passage P1c of the second header unit 52 from the plurality of heat transfer passages P1a, and then merges in the header flow passage P1c, the second header unit 52 penetrating through the center portion 17 of the plurality of heat transfer tubes 10. The refrigerant that merges in the header flow passage P1c flows through the header flow passage P1c, and then flows out to the outside of the heat exchanger 100 from the refrigerant inlet/outlet 52a of the second header unit 52 (see FIG. 1).

The heat exchanger 100 shown in FIG. 1 to FIG. 5 is merely an example of the heat exchanger 100 of the present disclosure, and the numbers and shapes of heat transfer tubes 10, heat transfer passages P1a, header flow passages P1b, and header flow passages P1c may be suitably changed. For example, each heat transfer tube 10 may include fins serving as heat transfer promoting members. Each heat transfer tube 10 may include convex portions, such as dimples, that protrude into the flow passages P2 for air.

[Air-Conditioning Apparatus 200]

FIG. 6 is a refrigerant circuit diagram of an air-conditioning apparatus 200 in which the heat exchanger 100 of Embodiment 1 is mounted, for the case of a cooling operation. As shown in FIG. 6, the heat exchanger 100 constitutes a portion of a refrigerant circuit 250 through which refrigerant circulates in the air-conditioning apparatus 200. The heat exchanger 100 is used as either one or both of an outdoor-side heat exchanger 203 and an indoor-side heat exchanger 205, which will be described later.

The air-conditioning apparatus 200 includes a compressor 201, a flow switching device 202, and the outdoor-side heat exchanger 203, the flow switching device 202 switching the refrigerant flow passage, the outdoor-side heat exchanger 203 exchanging heat between outdoor air and refrigerant flowing through the outdoor-side heat exchanger 203. The air-conditioning apparatus 200 also includes an expansion valve 204 and the indoor-side heat exchanger 205, the expansion valve 204 reducing the pressure of refrigerant flowing through the expansion valve 204, the indoor-side heat exchanger 205 exchanging heat between indoor air and refrigerant flowing through the indoor-side heat exchanger 205. The air-conditioning apparatus 200 need not include the flow switching device 202.

In FIG. 6, the air-conditioning apparatus 200 is configured such that the compressor 201, the flow switching device 202, the outdoor-side heat exchanger 203, and the expansion valve 204 are provided in an outdoor unit 231, and the indoor-side heat exchanger 205 is provided in an indoor unit 232. The header units 50, each of which forms the refrigerant inlet/outlet of the heat exchanger 100 (see FIG. 2), are connected to the flow switching device 202 and the expansion valve 204 of the refrigerant circuit 250.

In the air-conditioning apparatus 200, the compressor 201, the flow switching device 202, the outdoor-side heat exchanger 203, the expansion valve 204, and the indoor-side heat exchanger 205 are connected by refrigerant pipes 255 to form the refrigerant circuit 250 through which refrigerant circulates. The air-conditioning apparatus 200 shown in FIG. 6 can perform either a cooling operation or a heating operation by switching the flow passage by the flow switching device 202.

The compressor 201 suctions low temperature and low pressure refrigerant, compresses the suctioned refrigerant, and then discharges high temperature and high pressure refrigerant. The flow switching device 202 is, for example, a four-way valve, and switches between the cooling operation and the heating operation by switching the flow direction of refrigerant. The flow switching device 202 connects the discharge side of the compressor 201 to the indoor-side heat exchanger 205 during the heating operation, and connects the discharge side of the compressor 201 to the outdoor-side heat exchanger 203 during the cooling operation.

The outdoor-side heat exchanger 203 exchanges heat between outdoor air and refrigerant flowing through the outdoor-side heat exchanger 203. As shown in FIG. 6, during the cooling operation, the outdoor-side heat exchanger 203 serves as a condenser 221 that condenses refrigerant by rejecting heat of the refrigerant to outdoor air. During the heating operation, the outdoor-side heat exchanger 203 serves as an evaporator that evaporates refrigerant to cool outdoor air due to the heat of vaporization from the evaporation of the refrigerant.

The expansion valve 204 is, for example, an electronic expansion valve in which the opening degree of the throttle is adjustable. By adjusting the opening degree, the expansion valve 204 controls the pressure of refrigerant that flows into the outdoor-side heat exchanger 203 or the indoor-side heat exchanger 205. Although the expansion valve 204 is provided in the outdoor unit 231 in Embodiment 1, the expansion valve 204 may be provided in the indoor unit 232. The installation position of the expansion valve 204 is not limited.

The indoor-side heat exchanger 205 exchanges heat between indoor air and refrigerant flowing through the indoor-side heat exchanger 205. As shown in FIG. 6, during the cooling operation, the indoor-side heat exchanger 205 serves as an evaporator 222 that evaporates refrigerant to cool outdoor air due to the heat of vaporization from the evaporation of the refrigerant. During the heating operation, the indoor-side heat exchanger 205 serves as a condenser that condenses refrigerant by rejecting heat of the refrigerant to outdoor air.

The air-conditioning apparatus 200 may also include an outdoor fan 203a and an indoor fan 205a for sending air to the outdoor-side heat exchanger 203 and the indoor-side heat exchanger 205. The outdoor fan 203a and the indoor fan 205a form the flow of air that flows through the flow passages P2 formed between the adjacent heat transfer tubes 10 (see FIG. 2).

In the air-conditioning apparatus 200, when the compressor 201 is operated, a refrigeration cycle is performed, in which refrigerant circulates through the compressor 201, the outdoor-side heat exchanger 203, the expansion valve 204, and the indoor-side heat exchanger 205, while the refrigerant undergoes a phase change.

During the cooling operation of the air-conditioning apparatus 200 shown in FIG. 7, refrigerant compressed by the compressor 201 is sent to the outdoor-side heat exchanger 203. In the outdoor-side heat exchanger 203, the refrigerant is condensed by releasing heat to outdoor air. Thereafter, the refrigerant is sent to the expansion valve 204, is reduced in pressure by the expansion valve 204, and is then sent to the indoor-side heat exchanger 205. Thereafter, the refrigerant is evaporated by absorbing heat from indoor air in the indoor-side heat exchanger 205, and then returns to the compressor 201. Accordingly, during the cooling operation of the air-conditioning apparatus 200, the outdoor-side heat exchanger 203 serves as the condenser 221, and the indoor-side heat exchanger 205 serves as the evaporator 222.

During the heating operation of the air-conditioning apparatus 200, refrigerant compressed by the compressor 201 is sent to the indoor-side heat exchanger 205. In the indoor-side heat exchanger 205, the refrigerant is condensed by releasing heat to indoor air. Thereafter, the refrigerant is sent to the expansion valve 204, is reduced in pressure by the expansion valve 204, and is then sent to the outdoor-side heat exchanger 203. Thereafter, the refrigerant is evaporated by absorbing heat from outdoor air in the outdoor-side heat exchanger 203, and then returns to the compressor 201. Accordingly, during the heating operation of the air-conditioning apparatus 200, the outdoor-side heat exchanger 203 serves as an evaporator, and the indoor-side heat exchanger 205 serves as a condenser.

[Manner of Operation and Advantageous Effects of Heat Exchanger 100]

The heat exchanger 100 includes the plurality of heat transfer tubes 10 arranged in the first direction D1, each of the plurality of heat transfer tubes 10 extending in the second direction D2, which intersects the first direction D1, each of the plurality of heat transfer tubes 10 having both end portions in the second direction D2 sealed, the plurality of heat transfer tubes being configured to allow refrigerant to flow therethrough 10. Each of the plurality of heat transfer tubes 10 has the plurality of through holes 30 formed at positions inward of both end portions of each of the plurality of heat transfer tubes 10, the plurality of through holes 30 allowing the outside and the inner space of each of the plurality of heat transfer tubes 10 to be in communication. The plurality of heat transfer tubes 10 include the plurality of coupling units 12 that directly couple the plurality of through holes 30 of the adjacent heat transfer tubes 10 from among the plurality of heat transfer tubes 10. Alternatively, the plurality of heat transfer tubes 10 include the plurality of header pipes 80 that are inserted into the plurality of through holes 30 to couple the plurality of through holes 30 of the adjacent heat transfer tubes 10 from among the plurality of heat transfer tubes 10. The plurality of coupling units 12 or the plurality of header pipes 80 form the plurality of header units 50 formed to extend in the first direction D1. Each of the plurality of header units 50 allows refrigerant communication between the inner spaces of the plurality of heat transfer tubes 10, and forms the refrigerant inlet/outlet of the heat transfer tube group 15 constituted of the plurality of heat transfer tubes 10. The plurality of header units 50 are provided at the position that divides the plurality of heat transfer tubes 10 into the upper portion and the lower portion in the gravity direction.

The heat exchanger 100 includes the plurality of header units 50, each of which is formed by coupling the plurality of through holes 30 by the coupling units 12 or the header pipe 80, and the plurality of header units 50 are provided at the position that divides the plurality of heat transfer tubes 10 into the upper portion and the lower portion in the gravity direction. Compared with the case where the plurality of header units 50 are not provided at the position that divides the plurality of heat transfer tubes 10 into the upper portion and the lower portion in the gravity direction, the heat exchanger 100 can shorten the distance that refrigerant rises in the heat transfer tubes 10. The heat exchanger 100 can shorten the distance that refrigerant rises and hence, compared with the case where the plurality of header units 50 are not provided at the position that divides the plurality of heat transfer tubes 10 into the upper portion and the lower portion in the gravity direction, the head difference can be reduced, and thus liquid stagnation can be reduced.

The plurality of header units 50 are provided at the center portion 17 of the plurality of heat transfer tubes 10 in the second direction D2. Compared with the case where the plurality of header units 50 are not provided at the center portion 17 of the plurality of heat transfer tubes 10, the heat exchanger 100 can shorten the distance that refrigerant flowing out from the header unit 50 or refrigerant flowing into the header unit 50 rises in the heat transfer tubes 10. The heat exchanger 100 can shorten the distance that refrigerant rises and hence, compared with the case where the plurality of header units 50 are not provided at the position that divides the plurality of heat transfer tubes 10 into the upper portion and the lower portion in the gravity direction, the head difference can be reduced, and thus liquid stagnation can be reduced. In addition, in the heat exchanger 100, the plurality of header units 50 are provided at the center portion 17 of the plurality of heat transfer tubes 10 and hence, the refrigerant inlet and the refrigerant outlet can be collectively provided at the center portion, thus allowing pipes to be routed easily.

Each of the plurality of heat transfer tubes 10 includes the partition unit 70 disposed in the inner space of the tube wall 11, extending in the second direction D2, and configured to divide the inner space in the third direction D3 orthogonal to the first direction D1 and to the second direction D2. Both ends of the partition unit 70 in the second direction D2 are located at positions inward of the ends of the heat transfer passage P1a of the heat transfer tube 10 on both sides in the second direction D2. The plurality of header units 50 include the first header unit 51 and the second header unit 52, the first header unit 51 forming the refrigerant inflow port, the second header unit 52 forming the refrigerant outflow port. The first header unit 51 and the second header unit 52 are provided on both sides of the partition unit 70 in the third direction D3 with the partition unit 70 interposed therebetween. The heat exchanger 100 includes the partition units 70, and thus can easily cause refrigerant flowing into the heat exchanger 100 from the first header unit 51 to be branched toward the upper portion and the lower portion. In addition, the flow passage in the heat transfer tube 10 is narrowed and hence, it is possible to increase the flow velocity of rising refrigerant.

Therefore, compared with the case where the heat exchanger does not include the partition unit 70, the heat exchanger 100 can easily cause refrigerant to rise and hence, the head difference can be reduced, and thus liquid stagnation can be reduced.

The air-conditioning apparatus 200 includes the heat exchanger 100. The air-conditioning apparatus 200 includes the heat exchanger 100, and thus can achieve the above-described advantageous effects of the heat exchanger 100.

Embodiment 2

FIG. 7 is a perspective view showing a heat transfer tube 10 of a heat exchanger 100 according to Embodiment 2. FIG. 8 is a conceptual sectional view, taken along line A-A, of the heat transfer tube 10 shown in FIG. 3 of the heat exchanger 100 according to Embodiment 2, as viewed in the direction of arrows. The heat exchanger 100 of Embodiment 2 is obtained by changing the configuration of the heat transfer tubes 10 of the heat exchanger 100 of Embodiment 1. Constitutional elements having the same functions and manner of operations as those in Embodiment 1 are given the same reference symbols, and the description of such constitutional elements will be omitted.

As shown in FIG. 7 and FIG. 8, the partition unit 70 of the heat exchanger 100 according to Embodiment 2 is provided at a position offset in either direction in the third direction D3. The partition unit 70 is provided at a position closer to the first header unit 51 than the center portion in the third direction D3.

The heat exchanger 100 is formed such that the flow passage cross-sectional area of the inner space on the first header unit 51 side is smaller than the flow passage cross-sectional area of the inner space on the second header unit 52 side. That is, the heat exchanger 100 is formed such that the flow passage cross-sectional area of the first flow passage P1a1 is smaller than the flow passage cross-sectional area of the second flow passage P1a2.

Assume that the heat exchanger 100 includes header units 50 in which refrigerant flowing through the first header unit 51 has a higher proportion of liquid component to gas component than refrigerant flowing through the second header unit 52. In the heat exchanger 100, refrigerant flowing through the inner space on the first header unit 51 side has a higher proportion of liquid component to gas component than refrigerant flowing through the inner space on the second header unit 52 side. In the heat exchanger 100, refrigerant flowing through the first flow passage P1a1 has a higher proportion of liquid component to gas component than refrigerant flowing through the second flow passage P1a2. In the heat exchanger 100, refrigerant flowing through the inner space on the first header unit 51 side has a higher ratio of liquid component to gas component than refrigerant flowing through the inner space on the second header unit 52 side.

For example, the first header unit 51 is a header unit 50 into which refrigerant flows when the heat exchanger 100 serves as an evaporator, whereas the first header unit 51 is a header unit 50 from which refrigerant flows out when the heat exchanger 100 serves as an evaporator. In the example shown in FIG. 6, the heat exchanger 100 according to Embodiment 2 is used as the indoor-side heat exchanger 205.

[Manner of Operation and Advantageous Effects of Heat Exchanger 100]

In the heat exchanger 100 of Embodiment 2, the partition unit 70 is provided at the position closer to the first header unit 51 than the center portion in the third direction D3. Therefore, each heat transfer tube 10 of the heat exchanger 100 is formed such that the flow passage cross-sectional area of the inner space on the first header unit 51 side is smaller than the flow passage cross-sectional area of the inner space on the second header unit 52 side. In the heat transfer tube 10 of the heat exchanger 100, refrigerant flowing through the inner space on the first header unit 51 side has a higher proportion of liquid component to gas component than refrigerant flowing through the inner space on the second header unit 52 side.

The heat exchanger 100 has the above-mentioned configuration and hence, refrigerant with a higher proportion of liquid component has a higher flow velocity than refrigerant with a higher proportion of gas component. Accordingly, compared with the case where the heat exchanger does not have the above-mentioned configuration, it is easy to cause refrigerant to rise and hence, the head difference can be further reduced, and thus liquid stagnation can be reduced. The heat exchanger 100 has the above-mentioned configuration and hence, refrigerant with a higher proportion of liquid component, which easily allows heat transfer, has a higher flow velocity than refrigerant with a higher proportion of gas component, so that a heat transfer rate is increased, and thus the performance of the heat exchanger is enhanced.

The air-conditioning apparatus 200 includes the heat exchanger 100. The air-conditioning apparatus 200 includes the heat exchanger 100, and thus can achieve the above-described advantageous effects of the heat exchanger 100.

Embodiment 3

FIG. 9 is a perspective view showing a portion of the inner surface of a heat transfer tube 10 of a heat exchanger 100 according to Embodiment 3. The heat exchanger 100 of Embodiment 3 is obtained by changing the configuration of the heat transfer tubes 10 of the heat exchanger 100 of Embodiment 1. Constitutional elements having the same functions and manner of operations as those in Embodiment 1 and Embodiment 2 are given the same reference symbols, and the description of such constitutional elements will be omitted.

Each of the plurality of heat transfer tubes 10 includes at least one convex portion 60 protruding into the inner space of the heat transfer tube 10. The convex portions 60 are formed to have a protrusion shape. One convex portion 60 may be provided, or a plurality of convex portions 60 may be provided. In the heat exchanger 100, the heat transfer passage P1a in each heat transfer tube 10 can be narrowed by the convex portions 60. Refrigerant flowing through a narrowed space has a higher flow velocity than refrigerant flowing through a space that is not narrowed.

It is desirable that the convex portions 60 be provided at positions closer to the through hole 30 than both end portions of the heat transfer tube 10 in the second direction D2. It is preferable that the convex portions 60 be provided at positions closer to the header unit 50 than both end portions of the heat transfer tube 10 in the second direction D2. By providing the convex portions 60 at the positions close to the through hole 30 or the header unit 50, the heat exchanger 100 can increase the flow velocity of refrigerant after the refrigerant flows into the header unit 50.

It is particularly preferable that the convex portions 60 be provided above the through hole 30 or the header unit 50. By providing the convex portions 60 above the through hole 30 or the header unit 50, the convex portions 60 can impart momentum to refrigerant flowing upward.

[Manner of Operation and Advantageous Effects of Heat Exchanger 100]

In the heat exchanger 100 according to Embodiment 3, each of the plurality of heat transfer tubes 10 includes at least one convex portion 60 protruding into the inner space of the heat transfer tube 10. In the heat exchanger 100, the convex portions 60 are provided in the heat transfer tube 10 and hence, the convex portions 60 act as fluid resistances, and narrow the inner space of the heat transfer tube 10, and thus the flow velocity of liquid refrigerant increases. Compared with the case where the convex portions 60 are not provided, the heat exchanger 100 can increase the flow velocity of refrigerant in the heat transfer tube 10 and hence, it is easy to cause refrigerant to rise, so that the head difference can be reduced, and thus liquid stagnation can be reduced. In the heat exchanger 100, the drift of liquid refrigerant can be controlled by changing the positions of the convex portions 60, and the convex portions 60 can also achieve a function of adjusting refrigerant distribution in the heat transfer tube 10 while reducing liquid stagnation and hence, it is possible to enhance the performance of the heat exchanger.

The air-conditioning apparatus 200 includes the heat exchanger 100. The air-conditioning apparatus 200 includes the heat exchanger 100, and thus can achieve the above-described advantageous effects of the heat exchanger 100.

Embodiment 4

FIG. 10 is a conceptual view of a heat exchanger 100 according to Embodiment 4, as viewed in the first direction D1. FIG. 11 is a conceptual view of a modification of the heat exchanger 100 according to Embodiment 4, as viewed in the first direction D1. The heat exchanger 100 of Embodiment 4 is obtained by changing the configuration of the heat transfer tube 10 of the heat exchanger 100 of Embodiment 1. In FIG. 10, a vertical partition unit 90 provided in the heat transfer tube 10 is shown by a broken line. Constitutional elements having the same functions and manner of operations as those in Embodiment 1 to Embodiment 3 are given the same reference symbols, and the description of such constitutional elements will be omitted.

As shown in FIG. 10 and FIG. 11, each of the plurality of heat transfer tubes 10 includes at least one vertical partition unit 90 that is disposed in the inner space of the tube wall 11, and extends in the inner space in the third direction D3 orthogonal to the first direction D1 and to the second direction D2.

As shown in FIG. 10 and FIG. 11, the vertical partition unit 90 provides a partition between two header units 50 provided to be arranged in the second direction D2 from among the plurality of header units 50, thus dividing the inner space of the heat transfer tube 10 into the upper portion and the lower portion. Alternatively, as shown in FIG. 11, each vertical partition unit 90 provides a partition between two end-portion-side header units 55 provided to be arranged in the second direction D2 among the plurality of end-portion-side header units 55, thus dividing the inner space of the heat transfer tube 10 into the upper portion and the lower portion.

In the heat exchanger 100, two or more refrigerant paths are formed by the vertical partition unit 90, the plurality of header units 50, and the end-portion-side header units 55. FIG. 10 shows, as an example, a heat exchanger 100 having two refrigerant paths. FIG. 11 shows, as an example, a heat exchanger 100 having four refrigerant paths.

As shown in FIG. 10, for example, each of the plurality of heat transfer tubes 10 includes the vertical partition unit 90 that is disposed in the inner space of the tube wall 11 to provide a partition between the first header unit 51 and the second header unit 52. The vertical partition unit 90 extends in the inner space of the heat transfer tube 10 in the third direction D3 orthogonal to the first direction D1 and to the second direction D2, and divides the inner space of the heat transfer tube 10 into the upper portion and the lower portion. The inner space of the heat transfer tube 10 is divided into an upper space 10f and a lower space 10g by the vertical partition unit 90.

The vertical partition unit 90 is a plate-shaped or rod-shaped member that extends in the third direction D3 in the inner space of the heat transfer tube 10. Although the vertical partition unit 90 shown in FIG. 10 is formed to have a substantially Z shape when viewed in the first direction D1, the vertical partition unit 90 is not limited to such a shape. For example, the vertical partition unit 90 may be formed to have a straight shape inclined such that both ends in the third direction D3 have different height positions, when viewed in the first direction D1.

The vertical partition unit 90 is provided to connect the tube side wall part 10a and the tube side wall part 10b (see FIG. 4) to each other. The vertical partition unit 90 is provided to extend between the tube side wall part 10a and the tube side wall part 10b.

The plurality of header units 50 include the first header unit 51 and the second header unit 52, the first header unit 51 forming a refrigerant inflow port, the second header unit 52 forming a refrigerant outflow port.

The plurality of coupling units 12 or the plurality of header pipes 80 form the plurality of end-portion-side header units 55 formed to extend in the first direction D1. Each of the end-portion-side header units 55 allows refrigerant communication between the inner spaces of the plurality of heat transfer tubes 10, and forms the refrigerant inlet/outlet of the heat transfer tube group 15 constituted of the plurality of heat transfer tubes 10. The plurality of end-portion-side header units 55 are formed at positions closer to the end portions of the plurality of heat transfer tubes 10 than the plurality of header units 50 in the second direction D2.

Each end-portion-side header unit 55 has a structure similar to the structure of the header unit 50. That is, the end-portion-side header unit 55 is formed by directly or indirectly connecting the through holes 30 of the heat transfer tubes 10 to each other. The end-portion-side header unit 55 is constituted of the coupling units 12 or the header pipe 80. The end-portion-side header unit 55 is provided at a position closer to the end portion of the heat transfer tube 10 than the header unit 50 provided at the center portion 17.

The plurality of end-portion-side header units 55 include a third header unit 56 and a fourth header unit 57, the third header unit 56 forming a refrigerant inflow port, the fourth header unit 57 forming a refrigerant outflow port.

The third header unit 56 is formed at a position lower than the first header unit 51 and the second header unit 52, and forms the refrigerant inflow port into which refrigerant flows before flowing out from the second header unit 52. The fourth header unit 57 is formed at a position higher than the first header unit 51 and the second header unit 52, and forms the refrigerant outflow port from which refrigerant flows out after flowing into the heat transfer tube 10 from the first header unit 51.

A header flow passage P1e or a header flow passage P1f is formed in the header pipe 80 or the coupling units 12. For example, the header pipe 80 or the coupling units 12 that forms the third header unit 56 forms the header flow passage P1e, and the header pipe 80 or the coupling units 12 that forms the fourth header unit 57 forms the header flow passage P1f.

The refrigerant flow passage in the heat exchanger 100 of Embodiment 4 includes the plurality of heat transfer passages P1a, the header flow passage P1b, and the header flow passage P1c (see FIG. 3), the header flow passage P1b and the header flow passage P1c being provided at the center portion 17 of the heat exchanger 100 in such a way as to be arranged in the front-rear direction. The refrigerant flow passage in the heat exchanger 100 also includes the header flow passage Pe and the header flow passage P1f, which are provided at the positions closer to the end portions in the second direction D2 than the center portion 17 of the heat exchanger 100.

Each heat transfer passage P1a is in communication with the header flow passage P1e and the header flow passage P1f at the positions close to the end portions of the heat transfer passage P1a in the longitudinal direction of the heat transfer tube 10 (the second direction D2). The header flow passage P1e and the header flow passage P1f are in communication with the plurality of heat transfer passages P1a. In the case where the coupling units 12 are provided (see FIG. 2), for example, the through holes 30a, the through holes 30b, and the hollow parts Sg of the coupling units 12 described above constitute the header flow passage P1e and the header flow passage P1f, and refrigerant flows through the hollow parts Sg.

In the heat exchanger 100, the header flow passage P1b, the header flow passage P1c, the header flow passage P1e, and the header flow passage P1f are formed in the heat transfer tubes 10, being heat exchange members, and hence, it is unnecessary to provide a header unit outside the plurality of heat transfer tubes 10.

[Manner of Operation and Advantageous Effects of Heat Exchanger 100]

FIG. 12 is a conceptual view of a heat exchanger 100L according to a comparative example, as viewed in the first direction D1. The heat exchanger 100L according to the comparative example is a heat exchanger of the related art that includes header units 50L at both end portions of a heat transfer tube 10L in the second direction D2. The heat exchanger 100 according to the comparative example includes the header units 50L at both end portions of the heat transfer tube 10L in the second direction D2 and hence, an effective area E for heat exchange with the heat transfer tube 10L is reduced compared with the case where the heat exchanger does not include the header units 50.

In the heat exchanger 100 according to Embodiment 4, the plurality of coupling units 12 or the plurality of header pipes 80 form the plurality of end-portion-side header units 55 formed to extend in the first direction D1. Each of the end-portion-side header units 55 allows refrigerant communication between the inner spaces of the plurality of heat transfer tubes 10, and forms the refrigerant inlet/outlet of the heat transfer tube group 15 constituted of the plurality of heat transfer tubes 10. The plurality of end-portion-side header units 55 are formed at the positions closer to the end portions of the plurality of heat transfer tubes 10 than the plurality of header units 50 in the second direction D2. Each of the plurality of heat transfer tubes 10 includes at least one vertical partition unit 90 disposed in the inner space of the tube wall 11, extending in the inner space in the third direction D3 orthogonal and to the first direction D1 and to the second direction D2, and configured to divide the inner space of the heat transfer tube 10 into the upper portion and the lower portion. The vertical partition unit 90 provides a partition between two header units 50 provided to be arranged in the second direction D2 from among the plurality of header units 50. Alternatively, the vertical partition unit 90 provides a partition between two end-portion-side header units 55 provided to be arranged in the second direction D2 among the plurality of end-portion-side header units 55. In the heat exchanger 100, two or more refrigerant paths are formed by the vertical partition unit 90, the plurality of header units 50, and the end-portion-side header units 55.

In the heat exchanger 100 according to Embodiment 4, the header units are directly provided to the heat transfer tube 10 by the plurality of header units 50 and the plurality of end-portion-side header units 55. Therefore, in the heat exchanger 100 according to Embodiment 4, there is no possibility of the effective area E for heat exchange being reduced by the header units unlike the heat exchanger 100L of the comparative example shown in FIG. 12.

In the case where the heat exchanger 100 according to Embodiment 4 has the same height as the heat exchanger 100L according to the comparative example, the effective area E for heat exchange in the heat exchanger 100 is larger than the effective area E for heat exchange in the heat exchanger 100L of the comparative example shown in FIG. 12. That is, as in the comparative example, in the heat exchanger 100L of the related art, the effective area for heat exchange is reduced due to the header units 50L disposed at the upper and lower portions of the heat transfer tube 10L. However, such an effective area for heat exchange is increased in the heat exchanger 100 of Embodiment 4. Therefore, compared with the heat exchanger 100L that does not have the above-mentioned configuration, the heat exchanger 100 according to Embodiment 4 has a larger effective area for heat exchange, and thus can enhance heat exchange efficiency.

The heat exchanger 100 according to Embodiment 4 includes at least one vertical partition unit 90 that divides the inner space of the heat transfer tube 10 into the upper portion and the lower portion. The heat exchanger 100 has a shorter distance that refrigerant rises than a heat exchanger that does not include the vertical partition unit 90. Therefore, compared with the heat exchanger that does not include the vertical partition unit 90, the heat exchanger 100 can reduce the head difference, thus reducing liquid stagnation, leading to enhancement of heat exchange efficiency.

The vertical partition unit 90 is disposed in the inner space of the tube wall 11 to provide a partition between the first header unit 51 and the second header unit 52. The third header unit 56 is formed at a position lower than the first header unit 51 and the second header unit 52, and forms a refrigerant inflow port into which refrigerant flows before flowing out from the second header unit 52. The fourth header unit 57 is formed at a position higher than the first header unit 51 and the second header unit 52, and forms a refrigerant outflow port from which refrigerant flows out after flowing into the heat transfer tube 10 from the first header unit 51. When the heat exchanger 100 is compared with the heat exchanger that does not have such a configuration, there is no possibility that the effective area E for heat exchange is reduced due to the header units, unlike the heat exchanger 100L of the comparative example shown in FIG. 12. Therefore, compared with the heat exchanger 100L that does not have such a configuration, the heat exchanger 100 according to Embodiment 4 has a larger effective area for heat exchange, and thus can enhance heat exchange efficiency.

The air-conditioning apparatus 200 includes the heat exchanger 100. The air-conditioning apparatus 200 includes the heat exchanger 100, and thus can achieve the above-described advantageous effects of the heat exchanger 100.

Embodiment 5

FIG. 13 is a conceptual view of a heat exchanger 100 according to Embodiment 5, as viewed in the first direction D1. Constitutional elements having the same functions and manner of operations as those in Embodiment 1 to Embodiment 4 are given the same reference symbols, and the description of such constitutional elements will be omitted.

A total flow passage cross-sectional area A of the plurality of heat transfer tubes 10, with the number of heat transfer tubes 10 given as N [pieces], can be obtained by the following formula (1).

$\begin{array}{cc}A=a\times N\left[m^2\right]& \left(1\right)\end{array}$

• • a: flow passage cross-sectional area [m²] of each of plurality of heat transfer tubes 10
  • N: the number of heat transfer tubes 10 [pieces]

When a differential pressure in the refrigerant flow passage (hereinafter referred to as “flow passage differential pressure”) is defined as ΔP_HEX, and a liquid head is defined as ΔP_HEAD, ΔP_HEX/ΔP_HEAD can be obtained by the following formula (2). The flow passage differential pressure ΔP_HEX is the differential pressure in a flow passage in which refrigerant flows as an upward flow, and the flow passage differential pressure ΔP_HEX is the differential pressure between the upper and lower ends of the heat transfer tube 10 of the heat transfer tube group 15.

$\begin{array}{cc}\Delta P_{\mathrm{HEX}}/\Delta P_{\mathrm{HEAD}}=\left(5.94635\times 10-4\times A-1.7503\right)/\left(8.4303H\mathrm{Sin}\theta +0.8779\right)>1& \left(2\right)\end{array}$

• • A: total flow passage cross-sectional area [m²] of plurality of heat transfer tubes 10
  • H: length [m] of heat transfer tubes 10 in second direction D2
  • θ: inclination angle [degree] of plurality of heat transfer tubes 10 relative to horizontal plane F, with first direction D1 taken as direction parallel to horizontal plane F

The structure is effective particularly when the length H [m] of the heat transfer tubes 10 in the second direction D2 is longer than 0.420 [m] (length H >0.420). In many heat exchangers that are used in outdoor units for car air conditioners, for example, and that use corrugated fins, the length of heat transfer tubes is approximately 0.300 [m], whereas in many heat exchangers used in outdoor units for buildings, the length of heat transfer tubes is 0.420 [m] or more.

According to the studies of the inventors, it was found that when the length H of the heat transfer tubes 10 is increased to, for example, approximately 0.420 [m], ΔP_HEX/ΔP_HEAD is reduced compared with the case where the length H of the heat transfer tubes 10 is 0.300 [m]. The inventors also found that when the length H of the heat transfer tubes of the heat exchanger is 0.420 [m] or more, the head difference occurs, so that liquid stagnation, where liquid refrigerant does not smoothly flow, occurs at portions of the heat exchanger. In the heat exchanger 100 according to Embodiment 5, even in the case where the length H [m] of the heat transfer tubes in the second direction D2 is more than 0.420 [m], when the above-mentioned formula (2) is satisfied, liquid stagnation can be reduced and hence, it is possible to enhance the performance of the heat exchanger.

The above-mentioned formula (2) is an empirical formula obtained by the inventors based on numerical analysis and experimental results. The formula (2) is obtained by formulating the flow passage differential pressure ΔP_HEX using the total flow passage cross-sectional area A [m²] of the plurality of heat transfer tubes 10, being the dominant shape parameter of the heat exchanger 100, and by formulating the liquid head ΔP_HEAD using the length H [m] of the heat transfer tubes 10, being the dominant shape parameter of the heat exchanger 100. The formula (2) is obtained by performing formulation within a range of conditions in which, for example, the heat exchanger 100 is used in the outdoor unit 231 for building use, store use, or home use (see FIG. 6).

[Manner of Operation and Advantageous Effects of Heat Exchanger 100]

In the case where the heat exchanger is mounted in the outdoor unit with the header unit horizontally installed, and with the heat transfer tubes extending in the gravity direction, there may be cases where liquid refrigerant fails to rise sufficiently in the heat transfer tube due to a long distance in the direction of the length H of the heat transfer tube, and thus remains stagnant.

The heat exchanger 100 according to Embodiment 5 satisfies ΔP_HEX/ΔP_HEAD=(5.94635×10−4×A−1.75030)/(8.4303H Sin θ+0.8779)>1. By using the heat exchanger 100 within the range of this formula, when the refrigerant flows as an upward flow in the heat transfer tube 100, it is possible to reduce the occurrence of liquid stagnation, where liquefied refrigerant fails to rise sufficiently due to gravity, and thus remains stagnant, and hence, it is possible to enhance the performance of the heat exchanger.

The air-conditioning apparatus 200 includes the heat exchanger 100. The air-conditioning apparatus 200 includes the heat exchanger 100, and thus can achieve the above-described advantageous effects of the heat exchanger 100.

Although Embodiments have been described, the present disclosure is not limited to only the above-described Embodiments. For example, respective Embodiments may be combined with each other.

REFERENCE SIGNS LIST

10: heat transfer tube, 10L: heat transfer tube, 10a: tube side wall part, 10b: tube side wall part, 10c: connecting wall part, 10d: connecting wall part, 10e: opening end, 10f: upper space, 10g: lower space, 11: tube wall, 12: coupling unit, 12a: coupling protrusion unit, 12b: coupling protrusion unit, 15: heat transfer tube group, 17: center portion, 20: tube sealing unit, 30: through hole, 30a: through hole, 30b: through hole, 50: header unit, 50L: header unit, 51: first header unit, 51a: inlet/outlet, 52: second header unit, 52a inlet/outlet, 55: end-portion-side header unit, 56: third header unit, 57: fourth header unit, 60: convex portion, 70: partition unit, 70a: upper end, 70b: lower end, 80: header pipe, 82: hole, 90: vertical partition unit, 100: heat exchanger, 100L: heat exchanger, 200: air-conditioning apparatus, 201: compressor, 202: flow switching device, 203: outdoor-side heat exchanger, 203a: outdoor fan, 204: expansion valve, 205: indoor-side heat exchanger, 205a: indoor fan, 221: condenser, 222: evaporator, 231: outdoor unit, 232: indoor unit, 250: refrigerant circuit, 255: refrigerant pipe, P1a: heat transfer passage, P1a1: first flow passage, P1a2: second flow passage, P1b: header flow passage, P1c: header flow passage, P1e: header flow passage, P1f: header flow passage, P2: flow passage, Sg: hollow part.

Claims

1. A heat exchanger comprising a plurality of heat transfer tubes arranged in a first direction, each of the plurality of heat transfer tubes extending in a second direction intersecting the first direction, each of the plurality of heat transfer tubes having both end portions in the second direction sealed, the plurality of heat transfer tubes being configured to allow refrigerant to flow therethrough, wherein

each of the plurality of heat transfer tubes has a plurality of through holes formed at positions inward of the both end portions, the plurality of through holes allowing an outside and an inner space of each of the plurality of heat transfer tubes to be in communication,

the plurality of heat transfer tubes include a plurality of coupling units or a plurality of header pipes, the plurality of coupling units being configured to directly couple the plurality of through holes of adjacent heat transfer tubes from among the plurality of heat transfer tubes, the plurality of header pipes being inserted into the plurality of through holes, and being configured to couple the plurality of through holes of adjacent heat transfer tubes from among the plurality of heat transfer tubes,

the plurality of coupling units or the plurality of header pipes constitute a plurality of header units formed to extend in the first direction, each of the plurality of header units allowing refrigerant communication between the inner spaces of the plurality of heat transfer tubes, and forming a refrigerant inlet/outlet of a heat transfer tube group constituted of the plurality of heat transfer tubes, and

the plurality of header units are provided at a position that divides the plurality of heat transfer tubes into an upper portion and a lower portion in a gravity direction.

2. The heat exchanger of claim 1, wherein

the plurality of header units are provided at a center portion of the plurality of heat transfer tubes in the second direction.

3. The heat exchanger of claim 1, wherein

each of the plurality of heat transfer tubes includes a tube wall in which a heat transfer passage is provided in the inner space, the heat transfer passage being configured to allow refrigerant to flow therethrough,

the tube wall includes tube side wall parts that face each other in the first direction, each of the tube side wall parts having the plurality of through holes,

each of the plurality of heat transfer tubes includes a partition unit disposed in the inner space of the tube wall, extending in the second direction, and configured to divide the inner space in a third direction orthogonal to the first direction and to the second direction,

both ends of the partition unit in the second direction are located at positions inward of ends of the heat transfer passage of the heat transfer tube on both sides in the second direction,

the plurality of header units includes a first header unit forming a refrigerant inflow port, and a second header unit forming a refrigerant outflow port, and

the first header unit and the second header unit are provided on both sides of the partition unit in the third direction with the partition unit interposed therebetween.

4. The heat exchanger of claim 3, wherein

refrigerant flowing through the inner space on a first header unit side has a higher proportion of a liquid component to a gas component than refrigerant flowing through the inner space on a second header unit side,

the partition unit is provided at a position closer to the first header unit than a center portion in the third direction, and

a flow passage cross-sectional area of the inner space on the first header unit side is smaller than a flow passage cross-sectional area of the inner space on the second header unit side.

5. The heat exchanger of claim 1, wherein

each of the plurality of heat transfer tubes includes a tube wall in which a heat transfer passage is provided in the inner space, the heat transfer passage being configured to allow refrigerant to flow therethrough,

the tube wall includes tube side wall parts that face each other in the first direction, the tube side wall parts having the plurality of through holes,

the plurality of coupling units or the plurality of header pipes constitute a plurality of end-portion-side header units formed to extend in the first direction, each of the plurality of end-portion-side header units allowing refrigerant communication between the inner spaces of the plurality of heat transfer tubes, and forming a refrigerant inlet/outlet of the heat transfer tube group constituted of the plurality of heat transfer tubes,

the plurality of end-portion-side header units are formed at positions closer to end portions of the plurality of heat transfer tubes than the plurality of header units in the second direction,

each of the plurality of heat transfer tubes includes at least one vertical partition unit disposed in the inner space of the tube wall, extending in the inner space in a third direction orthogonal to the first direction and to the second direction, and configured to divide the inner space into an upper portion and a lower portion by providing a partition between two header units provided to be arranged in the second direction from among the plurality of header units, or by providing a partition between two end-portion-side header units provided to be arranged in the second direction from among the plurality of end-portion-side header units, and

two or more refrigerant paths are formed by the at least one vertical partition unit, the plurality of header units, and the plurality of end-portion-side header units.

6. The heat exchanger of claim 5, wherein

the plurality of header units includes a first header unit forming a refrigerant inflow port, and a second header unit forming a refrigerant outflow port,

the at least one vertical partition unit is disposed in the inner space of the tube wall to provide a partition between the first header unit and the second header unit,

the plurality of end-portion-side header units includes a third header unit forming a refrigerant inflow port, and a fourth header unit forming a refrigerant outflow port,

the third header unit is formed at a position lower than the first header unit and the second header unit, and forms the refrigerant inflow port into which refrigerant flows before flowing out from the second header unit, and

the fourth header unit is formed at a position higher than the first header unit and the second header unit, and forms the refrigerant outflow port from which refrigerant flows out after flowing into the heat transfer tube from the first header unit.

7. The heat exchanger of claim 1, wherein

each of the plurality of heat transfer tubes includes at least one convex portion configured to protrude into the inner space of each of the plurality of heat transfer tubes.

8. The heat exchanger of claim 1, wherein

when a flow passage cross-sectional area a of each of the plurality of heat transfer tubes is defined as a [m2],

a total flow passage cross-sectional area A of the plurality of heat transfer tubes, with the number of heat transfer tubes given as N [pieces], is defined as A [m2]=a×N [m2],

a length of the plurality of heat transfer tubes in the second direction is defined as H [m],

an inclination angle of the plurality of heat transfer tubes relative to a horizontal plane, with the first direction taken as a direction parallel to the horizontal plane, is defined as θ [degree],

a differential pressure in a refrigerant flow passage is defined as ΔPHEX, and

a liquid head is defined as ΔPHEAD,

a relationship of ΔPHEX/ΔPHEAD=(5.94635×10−4×A−1.75030)/(8.4303H Sin θ+0.8779)>1 is satisfied.

9. An air-conditioning apparatus comprising the heat exchanger of claim 1.

10. The heat exchanger of claim 1, wherein

when a third direction is taken as a direction orthogonal to the first direction and to the second direction,

each of the plurality of heat transfer tubes includes a tube wall in which a heat transfer passage is provided in the inner space, the heat transfer passage being configured to allow refrigerant to flow through the heat transfer passage, and

the tube wall includes tube side wall parts facing each other in the first direction, a connecting wall part having a curved surface shape, and being configured to connect end portions on both sides in the third direction of the tube side wall parts facing each other in the first direction, and

each of the tube side wall parts has the plurality of through holes, and

the heat exchanger includes tube sealing units that close respective opening ends of the heat transfer tubes on both sides in the second direction.