In a stacking-type header including a first plate-shaped unit and a second plate-shaped unit, a distribution flow passage in the second plate-shaped unit includes at least one branching flow passage, in which the second plate-shaped unit includes at least one plate-shaped member having a groove formed as a flow passage, the groove having at least one branching portion for branching one branch part into a plurality of branch parts, in which the at least one branching flow passage is formed by closing the groove in a region other than a refrigerant inflow region and a refrigerant outflow region, and in which at least part of the refrigerant branched by flowing into the at least one branching flow passage sequentially passes through the one branch part and the plurality of branch parts, and flows out from the at least one branching flow passage through end portions of the groove.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national stage application of International Application No. PCT/JP2013/063601 filed on May 15, 2013, the disclosure of which is incorporated herein by reference.

The present invention relates to a stacking-type header, a heat exchanger, and an air-conditioning apparatus.

BACKGROUND ART

As a related-art stacking-type header, there is known a stacking-type header including a first plate-shaped unit having a plurality of outlet flow passages formed therein, and a second plate-shaped unit stacked on the first plate-shaped unit and having a distribution flow passage formed therein, for distributing refrigerant, which passes through an inlet flow passage to flow into the second plate-shaped unit, to the plurality of outlet flow passages formed in the first plate-shaped unit to cause the refrigerant to flow out from the second plate-shaped unit. The distribution flow passage includes a branching flow passage having a plurality of grooves in an entire peripheral direction extending perpendicular to a refrigerant inflow direction from a refrigerant inflow position. The refrigerant passing through the inlet flow passage to flow into the branching flow passage passes through the plurality of grooves to be branched into a plurality of flows, to thereby pass through the plurality of outlet flow passages formed in the first plate-shaped unit to flow out from the first plate-shaped unit (for example, see Patent Literature 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In such a stacking-type header, through reduction of the angular interval between the plurality of grooves, the number of paths (in other words, the number of heat transfer tubes) is increased. To prevent partition walls between the grooves from becoming too thin, it is necessary to increase a diameter of the inlet flow passage so that the grooves are arrange away from the center of the inlet flow passage. In other words, there is a problem in that the stacking-type header may be upsized in the entire peripheral direction perpendicular to the refrigerant inflow direction.

The present invention has been made in view of the above-mentioned problem, and has an object to provide a stacking-type header suppressed in upsize in an entire peripheral direction perpendicular to a refrigerant inflow direction. Further, the present invention has an object to provide a heat exchanger including such a stacking-type header. Further, the present invention has an object to provide an air-conditioning apparatus including such a heat exchanger.

Solution to Problem

According to one embodiment of the present invention, there is provided a stacking-type header, including: a first plate-shaped unit having a plurality of first outlet flow passages formed therein; and a second plate-shaped unit stacked on the first plate-shaped unit, the second plate-shaped unit having a distribution flow passage formed therein, the distribution flow passage being configured to distribute refrigerant, which passes through a first inlet flow passage to flow into the second plate-shaped unit, to the plurality of first outlet flow passages to cause the refrigerant to flow out from the second plate-shaped unit, in which the distribution flow passage includes at least one branching flow passage, in which the second plate-shaped unit includes at least one plate-shaped member having a groove formed as a flow passage, the groove having at least one branching portion for branching one branch part into a plurality of branch parts, in which the at least one branching flow passage is formed by closing the groove in a region other than a refrigerant inflow region and a refrigerant outflow region, and in which at least part of the refrigerant branched by flowing into the at least one branching flow passage sequentially passes through the one branch part and the plurality of branch parts, and flows out from the at least one branching flow passage through end portions of the groove.

Advantageous Effects of Invention

In the stacking-type header according to the one embodiment of the present invention, the distribution flow passage includes the at least one branching flow passage. The second plate-shaped unit includes the at least one plate-shaped member having the groove formed as the flow passage, the groove having the at least one branching portion for branching the one branch part into the plurality of branch parts. The at least one branching flow passage is formed by closing the groove in the region other than the refrigerant inflow region and the refrigerant outflow region. The at least part of the refrigerant branched by flowing into the at least one branching flow passage sequentially passes through the one branch part and the plurality of branch parts, and flows out from the at least one branching flow passage through the end portions of the groove. In the branching flow passage, the refrigerant branched at the refrigerant inflow position is further branched at the branching portion, and hence the number of branches at the refrigerant inflow position can be reduced, which suppresses the upsize of the stacking-type header in the entire peripheral direction perpendicular to the refrigerant inflow direction.

DESCRIPTION OF EMBODIMENTS

Now, a stacking-type header according to the present invention is described with reference to the drawings.

Note that, in the following, there is described a case where the stacking-type header according to the present invention distributes refrigerant flowing into a heat exchanger, but the stacking-type header according to the present invention may distribute refrigerant flowing into other devices. Further, the configuration, operation, and other matters described below are merely examples, and the present invention is not limited to such configuration, operation, and other matters. Further, in the drawings, the same or similar components are denoted by the same reference symbols, or the reference symbols therefor are omitted. Further, the illustration of details in the structure is appropriately simplified or omitted. Further, overlapping description or similar description is appropriately simplified or omitted.

A heat exchanger according to Embodiment 1 is described.

Configuration of Heat Exchanger

Now, the configuration of the heat exchanger according to Embodiment 1 is described.

FIG. 1is a view illustrating the configuration of the heat exchanger according to Embodiment 1.

As illustrated inFIG. 1, a heat exchanger1includes a stacking-type header2, a header3, a plurality of first heat transfer tubes4, a retaining member5, and a plurality of fins6.

The stacking-type header2includes a refrigerant inflow port2A and a plurality of refrigerant outflow ports2B. The header3includes a plurality of refrigerant inflow ports3A and a refrigerant outflow port3B. Refrigerant pipes are connected to the refrigerant inflow port2A of the stacking-type header2and the refrigerant outflow port3B of the header3. The plurality of first heat transfer tubes4are connected between the plurality of refrigerant outflow ports2B of the stacking-type header2and the plurality of refrigerant inflow ports3A of the header3.

The first heat transfer tube4is a flat tube having a plurality of flow passages formed therein. The first heat transfer tube4is made of, for example, aluminum. End portions of the plurality of first heat transfer tubes4on the stacking-type header2side are connected to the plurality of refrigerant outflow ports2B of the stacking-type header2under a state in which the end portions are retained by the plate-shaped retaining member5. The retaining member5is made of, for example, aluminum. The plurality of fins6are joined to the first heat transfer tubes4. The fin6is made of, for example, aluminum. It is preferred that the first heat transfer tubes4and the fins6be joined by brazing. Note that, inFIG. 1, there is illustrated a case where eight first heat transfer tubes4are provided, but the present invention is not limited to such a case.

Flow of Refrigerant in Heat Exchanger

Now, the flow of the refrigerant in the heat exchanger according to Embodiment 1 is described.

The refrigerant flowing through the refrigerant pipe passes through the refrigerant inflow port2A to flow into the stacking-type header2to be distributed, and then passes through the plurality of refrigerant outflow ports2B to flow out toward the plurality of first heat transfer tubes4. In the plurality of first heat transfer tubes4, the refrigerant exchanges heat with air supplied by a fan, for example. The refrigerant flowing through the plurality of first heat transfer tubes4passes through the plurality of refrigerant inflow ports3A to flow into the header3to be joined, and then passes through the refrigerant outflow port3B to flow out toward the refrigerant pipe. The refrigerant can reversely flow.

Configuration of Laminated Header

Now, the configuration of the stacking-type header of the heat exchanger according to Embodiment 1 is described.

FIG. 2is a perspective view of the heat exchanger according to Embodiment 1 under a state in which the stacking-type header is disassembled.

As illustrated inFIG. 2, the stacking-type header2includes a first plate-shaped unit11and a second plate-shaped unit12. The first plate-shaped unit11and the second plate-shaped unit12are stacked on each other.

The first plate-shaped unit11is stacked on the refrigerant outflow side. The first plate-shaped unit11includes a first plate-shaped member21. The first plate-shaped unit11has a plurality of first outlet flow passages11A formed therein. The plurality of first outlet flow passages11A correspond to the plurality of refrigerant outflow ports2B inFIG. 1.

The first plate-shaped member21has a plurality of flow passages21A formed therein. The plurality of flow passages21A are each a through hole having an inner peripheral surface shaped conforming to an outer peripheral surface of the first heat transfer tube4. When the first plate-shaped member21is stacked, the plurality of flow passages21A function as the plurality of first outlet flow passages11A. The first plate-shaped member21has a thickness of about 1 mm to 10 mm, and is made of aluminum, for example. When the plurality of flow passages21A are formed by press working or other processing, the work is simplified, and the manufacturing cost is reduced.

The end portions of the first heat transfer tubes4are projected from the surface of the retaining member5. When the first plate-shaped unit11is stacked on the retaining member5so that the inner peripheral surfaces of the first outlet flow passages11A are fitted to the outer peripheral surfaces of the respective end portions of the first heat transfer tubes4, the first heat transfer tubes4are connected to the first outlet flow passages11A. The first outlet flow passages11A and the first heat transfer tubes4may be positioned through, for example, fitting between a convex portion formed in the retaining member5and a concave portion formed in the first plate-shaped unit11. In such a case, the end portions of the first heat transfer tubes4may not be projected from the surface of the retaining member5. The retaining member5may be omitted so that the first heat transfer tubes4are directly connected to the first outlet flow passages11A. In such a case, the component cost and the like are reduced.

The second plate-shaped unit12is stacked on the refrigerant inflow side. The second plate-shaped unit12includes a second plate-shaped member22and a plurality of third plate-shaped members23_1and23_2. The second plate-shaped unit12has a distribution flow passage12A formed therein. The distribution flow passage12A includes a first inlet flow passage12aand a plurality of branching flow passages12b. The first inlet flow passage12acorresponds to the refrigerant inflow port2A inFIG. 1.

The second plate-shaped member22has a flow passage22A formed therein. The flow passage22A is a circular through hole. When the second plate-shaped member22is stacked, the flow passage22A functions as the first inlet flow passage12a. The second plate-shaped member22has a thickness of about 1 mm to 10 mm, and is made of aluminum, for example. When the flow passage22A is formed by press working or other processing, the work is simplified, and the manufacturing cost and the like are reduced.

For example, a fitting or other such component is provided on the surface of the second plate-shaped member22on the refrigerant inflow side, and the refrigerant pipe is connected to the first inlet flow passage12athrough the fitting or other such component. The inner peripheral surface of the first inlet flow passage12amay be shaped to be fitted to the outer peripheral surface of the refrigerant pipe so that the refrigerant pipe may be directly connected to the first inlet flow passage12awithout using the fitting or other such component. In such a case, the component cost and the like are reduced.

The third plate-shaped member23_1has a flow passage23A formed therein. The third plate-shaped member23_2has a plurality of flow passages23B formed therein. The flow passages23A and23B are each a through groove. The shape of the through groove is described in detail later. When the plurality of third plate-shaped members23_1and23_2are stacked, each of the flow passages23A and23B functions as the branching flow passage12b. The plurality of third plate-shaped members23land23_2each have a thickness of about 1 mm to 10 mm, and are made of aluminum, for example. When the flow passages23A and23B are formed by press working or other processing, the work is simplified, and the manufacturing cost and the like are reduced.

In the following, in some cases, the plurality of third plate-shaped members23_1and23_2are collectively referred to as the third plate-shaped member23. In the following, in some cases, the retaining member5, the first plate-shaped member21, the second plate-shaped member22, and the third plate-shaped member23are collectively referred to as the plate-shaped member.

The branching flow passage12bformed by the flow passage23A branches the refrigerant flowing therein into four flows to cause the refrigerant to flow out therefrom through end portions of the groove. The branching flow passage12bformed by the flow passage23B branches the refrigerant flowing therein into two flows to cause the refrigerant to flow out therefrom through end portions of the groove. Therefore, when the number of the first heat transfer tubes4to be connected is eight, two third plate-shaped members23are required. When the number of the first heat transfer tubes4to be connected is sixteen, two third plate-shaped members23each having the flow passages23A formed therein are required. There may be provided a single third plate-shaped member23having the flow passage23A formed therein and two third plate-shaped members23each having the flow passages23B formed therein. The number of the first heat transfer tubes4to be connected is not limited to powers of 2. In such a case, the branching flow passage12band a non-branching flow passage may be combined with each other. Note that, there may be provided four first heat transfer tubes4to be connected and a single third plate-shaped member23having the flow passage23A formed therein. Further, the lamination order of the third plate-shaped member23_1and the third plate-shaped member23_2may be reversed. In such a case, for example, a single flow passage23B may be formed in the third plate-shaped member23_2, and two flow passages23A may be formed in the third plate-shaped member23_1.

FIG. 3are a developed view of the stacking-type header of the heat exchanger according to Embodiment 1. Note that,FIG. 3(b)is a detailed view of a branching portion23f.

As illustrated inFIG. 3(a), the flow passage23A formed in the third plate-shaped member23has a shape in which an end portion23a, an end portion23b, an end portion23c, and an end portion23dare connected to each other through a straight-line part23eand two branching portions23f. The straight-line part23eis perpendicular to the gravity direction. The branching flow passage12bis formed by closing, by a member stacked adjacent on the refrigerant inflow side, the flow passage23A in a region other than a partial region23i(hereinafter referred to as “opening port23i”) between an end portion23gand an end portion23hof the straight-line part23e, and closing, by a member stacked adjacent on the refrigerant outflow side, a region other than the end portions23ato23d.

In order to cause the refrigerant, which flows into the opening port23iand is branched thereat, and is further branched at the branching portions23f, to flow out from the flow passage23A at different heights, the end portions23ato23dare positioned at heights different from one another. In particular, when one of the branching portions23fis positioned on the upper side relative to the straight-line part23e, and the other thereof is positioned on the lower side relative to the straight-line part23e, each distance from the opening port23ialong the flow passage23A to each of the end portions23ato23dcan be less biased without complicating the shape. Further, when each of the end portion23aand the end portion23cis positioned on the upper side relative to the branching portion23f, and each of the end portion23band the end portion23dis positioned on the lower side relative to the branching portion23f, each distance from the opening port23ialong the flow passage23A to each of the end portions23ato23dcan be less biased without complicating the shape. When the array direction of the end portions23ato23dis set parallel to the longitudinal direction of the third plate-shaped member23, the dimension of the third plate-shaped member23in the transverse direction can be decreased, which reduces the component cost, the weight, and the like. Further, when the array direction of the end portions23ato23dis set parallel to the array direction of the first heat transfer tubes4, space saving can be achieved in the heat exchanger1.

The flow passage23B formed in the third plate-shaped member23is similar to the flow passage23A formed in the third plate-shaped member23except that the flow passage23B includes the two end portions23aand23b, and does not include the branching portions23f. In other words, the branching flow passage12bis formed by closing, by a member stacked adjacent on the refrigerant inflow side, the flow passage23B in a region other than the opening port23i, and closing, by a member stacked adjacent on the refrigerant outflow side, the flow passage23B in a region other than the end portions23aand23b. The branching flow passage12bmay be formed by a flow passage23B having a different shape.

As illustrated inFIG. 3(b), the branching portion23fbraches a branch part23jinto branch parts23kand23l. The branch part23jcommunicates with the opening port23i. The branch part23kcommunicates with each of the end portions23aand23c, and the branch part23lcommunicates with each of the end portions23band23d. The branch part23jextends straight toward a center23mof the branching portion in a direction parallel to the gravity direction. A part ranging from the center23mof the branching portion to an end portion of a straight-line part of the branching portion is defined as a straight-line part23n. The branch parts23kand23lextend straight from the center23mof the branching portion in directions opposite to each other and perpendicular to the gravity direction. Parts ranging from the center23mof the branching portion to end portions of straight line parts are defined as straight-line parts23oand23p, respectively.

FIG. 4is a developed view of the stacking-type header of the heat exchanger according to Embodiment 1.

As illustrated inFIG. 4, when the array direction of the first heat transfer tubes4is not parallel to the gravity direction, in other words, when the array direction intersects with the gravity direction, the straight-line part23eis not perpendicular to the longitudinal direction of the third plate-shaped member23. In other words, the stacking-type header2is not limited to a stacking-type header in which the plurality of first outlet flow passages11A are arrayed along the gravity direction, and may be used in a case where the heat exchanger1is installed in an inclined manner, such as a heat exchanger for a wall-mounting type room air-conditioning apparatus indoor unit, an outdoor unit for an air-conditioning apparatus, or a chiller outdoor unit. Note that, inFIG. 4, there is illustrated a case where the longitudinal direction of the cross section of the flow passage21A formed in the first plate-shaped member21, in other words, the longitudinal direction of the cross section of the first outlet flow passage11A is perpendicular to the longitudinal direction of the first plate-shaped member21, but the longitudinal direction of the cross section of the first outlet flow passage11A may be perpendicular to the gravity direction.

The flow passage23A may not include the straight-line part23e. In such a case, a horizontal part of the flow passage23A, which is perpendicular to the gravity direction and positioned between a lower end of the upper branching portion23fand an upper end of the lower branching portion23f, serves as the opening port23i. In a case where the flow passage23A includes the straight-line part23e, when the refrigerant is branched at the opening port23i, the angles of the respective branching directions with respect to the gravity direction are uniform, which reduces the influence of the gravity.

FIG. 5are views each illustrating a modified example of the flow passage formed in the third plate-shaped member of the heat exchanger according to Embodiment 1.

As illustrated inFIG. 5(a), the flow passage23A may include eight end portions and six branching portions23f. In such a case, a single branching flow passage12bcan branch the refrigerant flowing therein into eight flows, and hence the number of the third plate-shaped members23can be reduced. Further, the frequency of occurrence of brazing failure can be reduced. In other words, the number of the branching portions23fof the flow passage23A is not necessarily two. Through the changing of the number of the branching portions23f, the number of the branches for the refrigerant flowing therein may be changed freely.

As illustrated inFIG. 5(b), the flow passage23A may include three end portions and a single branching portion23f. For example, such a configuration is effective when the number of the first heat transfer tubes4to be connected is not powers of 2. In such a case, a flow-passage resistance in a passing region for the refrigerant flowing out from an end portion of the flow passage23A without passing through the branching portion23fof the flow passage23A may be increased to equalize flow rates of the refrigerant flowing out from the three end portions. When the shape of the flow passage (such as width of the flow passage, length of the flow passage, bending of the flow passage, and surface roughness of the flow passage) is optimized, the flow-passage resistance can be increased.

Flow of Refrigerant in Laminated Header

Now, the flow of the refrigerant in the stacking-type header of the heat exchanger according to Embodiment 1 is described.

As illustrated inFIG. 3andFIG. 4, the refrigerant passing through the flow passage22A of the second plate-shaped member22flows into the opening port23iof the flow passage23A formed in the third plate-shaped member23_1. The refrigerant flowing into the opening port23fhits against the surface of the member stacked adjacent to the third plate-shaped member23_1, and is branched into two flows respectively toward the end portion23gand the end portion23hof the straight-line part23e. The branched refrigerant sequentially passes through the branch part23jof the branching portion23fand each of the branch parts23kand23lto reach each of the end portions23ato23dof the flow passage23A and flows into the opening port23iof the flow passage23B formed in the third plate-shaped member23_2.

The refrigerant flowing into the opening port23iof the flow passage23B formed in the third plate-shaped member23_2hits against the surface of the member stacked adjacent to the third plate-shaped member23_2, and is branched into two flows respectively toward the end portion23gand the end portion23hof the straight-line part23e. The branched refrigerant reaches each of the end portions23aand23bof the flow passage23B, and passes through the flow passage21A of the first plate-shaped member21to flow into the first heat transfer tube4.

Method of Laminating Plate-like Members

Now, a method of stacking the respective plate-shaped members of the stacking-type header of the heat exchanger according to Embodiment 1 is described.

The respective plate-shaped members may be stacked by brazing. A both-side clad member having a brazing material rolled on both surfaces thereof may be used for all of the plate-shaped members or alternate plate-shaped members to supply the brazing material for joining. A one-side clad member having a brazing material rolled on one surface thereof may be used for all of the plate-shaped members to supply the brazing material for joining. A brazing-material sheet may be stacked between the respective plate-shaped members to supply the brazing material. A paste brazing material may be applied between the respective plate-shaped members to supply the brazing material. A both-side clad member having a brazing material rolled on both surfaces thereof may be stacked between the respective plate-shaped members to supply the brazing material.

Through lamination with use of brazing, the plate-shaped members are stacked without a gap therebetween, which suppresses leakage of the refrigerant and further secures the pressure resistance. When the plate-shaped members are pressurized during brazing, the occurrence of brazing failure is further suppressed. When processing that promotes formation of a fillet, such as forming a rib at a position at which leakage of the refrigerant is liable to occur, is performed, the occurrence of brazing failure is further suppressed.

Further, when all of the members to be subjected to brazing, including the first heat transfer tube4and the fin6, are made of the same material (for example, made of aluminum), the members may be collectively subjected to brazing, which improves the productivity. After the brazing in the stacking-type header2is performed, the brazing of the first heat transfer tube4and the fin6may be performed. Further, only the first plate-shaped unit11may be first joined to the retaining member5by brazing, and the second plate-shaped unit12may be joined by brazing thereafter.

FIG. 6is a perspective view of the heat exchanger according to Embodiment 1 under a state in which the stacking-type header is disassembled.FIG. 7is a developed view of the stacking-type header of the heat exchanger according to Embodiment 1.

In particular, a plate-shaped member having a brazing material rolled on both surfaces thereof, in other words, a both-side clad member may be stacked between the respective plate-shaped members to supply the brazing material. As illustrated inFIG. 6andFIG. 7, a plurality of both-side clad members24_1to24_4are stacked between the respective plate-shaped members. In the following, in some cases, the plurality of both-side clad members24_1to24_4are collectively referred to as the both-side clad member24. Note that, the both-side clad member24may be stacked between a part of the plate-shaped members, and a brazing material may be supplied between the remaining plate-shaped members by other methods.

The both-side clad member24has a flow passage24A, which passes through the both-side clad member24, formed in a region that is opposed to a refrigerant outflow region of the flow passage formed in the plate-shaped member stacked adjacent on the refrigerant inflow side. The flow passage24A formed in the both-side clad member24stacked between the second plate-shaped member22and the third plate-shaped member23is a circular through hole. The flow passage24A formed in the both-side clad member24_4stacked between the first plate-shaped member21and the retaining member5is a through hole having an inner peripheral surface shaped conforming to the outer peripheral surface of the first heat transfer tube4.

When the both-side clad member24is stacked, the flow passage24A functions as a refrigerant partitioning flow passage for the first outlet flow passage11A and the distribution flow passage12A. Under a state in which the both-side clad member24_4is stacked on the retaining member5, the end portions of the first heat transfer tubes4may be or not be projected from the surface of the both-side clad member24_4. When the flow passage24A is formed by press working or other processing, the work is simplified, and the manufacturing cost and the like are reduced. When all of the members to be subjected to brazing, including the both-side clad member24, are made of the same material (for example, made of aluminum), the members may be collectively subjected to brazing, which improves the productivity.

Through formation of the refrigerant partitioning flow passage by the both-side clad member24, in particular, the branched flows of refrigerant flowing out from the branching flow passage12bcan be reliably partitioned from each other. Further, by the amount of the thickness of each both-side clad member24, an entrance length for the refrigerant flowing into the branching flow passage12bor the first outlet flow passage11A can be secured, which improves the uniformity in distribution of the refrigerant. Further, the flows of the refrigerant can be reliably partitioned from each other, and hence the degree of freedom in design of the branching flow passage12bcan be increased.

Shape of Flow Passage of Third Plate-Like Member

Now, the flow passage formed in the third plate-shaped member of the stacking-type header of the heat exchanger according to Embodiment 1 is described in detail.

Note that, the description below is directed to a case where the branch part23jextends from below toward the center23mof the branching portion, the branch part23kextends upward from the center23mof the branching portion, and the branch part23lextends downward from the center23mof the branching portion. The same applies also to other cases.

FIG. 8is a view illustrating the branching portion of the flow passage formed in the third plate-shaped member of the heat exchanger according to Embodiment 1.

As illustrated inFIG. 8, a distance of the straight-line part23nof the branch part23jis defined as a straight-line distance L1. Further, a hydraulic equivalent diameter of the straight-line part23nis defined as a hydraulic equivalent diameter De1, and a ratio of the straight-line distance L1 to the hydraulic equivalent diameter De1 is defined as a straight-line ratio L1/De1. A ratio of a flow rate of the refrigerant flowing out from the branch part23kto a sum of a flow rate of the refrigerant flowing out from the branch part23kand a flow rate of the refrigerant flowing out from the branch part23lis defined as a distribution ratio R.

FIG. 9is a graph showing a relationship between the straight-line ratio and the distribution ratio in the branching portion of the flow passage formed in the third plate-shaped member of the heat exchanger according to Embodiment 1. Note that,FIG. 9shows a change in distribution ratio R when the straight-line ratio L1/De1 is changed.

As shown inFIG. 9, the distribution ratio R is changed so that the distribution ratio R is increased until the straight-line ratio L1/De1 reaches 10.0, and the distribution ratio R reaches 0.5 when the straight-line ratio L1/De1 is 10.0 or more. When the straight-line ratio L1/De1 is less than 10.0, because a region between the straight-line part23eand the straight-line part23nof the flow passage23A is not parallel to the gravity direction, the refrigerant flows into the center23mof the branching portion in a state of causing drift, and hence the distribution ratio R does not reach 0.5.

FIG. 10are graphs each showing a relationship between the straight-line ratio and an AK value of the heat exchanger in the branching portion of the flow passage formed in the third plate-shaped member of the heat exchanger according to Embodiment 1. Note that,FIG. 10(a)shows a change in AK value of the heat exchanger1when the straight-line ratio L1/De1 is changed.FIG. 10(b)shows a change in effective AK value of the heat exchanger1when the straight-line ratio L1/De1 is changed. The AK value is a multiplication value of a heat transfer area A [m2] of the heat exchanger1and an overall heat transfer coefficient K [J/(S·m2·K)] of the heat exchanger1, and the effective AK value is a value defined based on a multiplication value of the AK value and the above-mentioned distribution ratio R. As the effective AK value is higher, the performance of the heat exchanger1is enhanced.

On the other hand, as shown inFIG. 10(a), as the straight-line ratio L1/De1 is higher, an array interval of the first heat transfer tubes4is increased, in other words, the number of the first heat transfer tubes4is reduced, and thus the AK value of the heat exchanger1is reduced. Therefore, as shown inFIG. 10(b), the effective AK value is changed so that the effective AK value is increased until the straight-line ratio L1/De1 reaches 3.0, and the effective AK is decreased while reducing a decreasing amount when the straight-line ratio L1/De1 is 3.0 or more. That is, when the straight-line ratio L1/De1 is set to 3.0 or more, the effective AK value, in other words, the performance of the heat exchanger1can be maintained.

As illustrated inFIG. 8, a distance of the straight-line part23oof the branch part23kis defined as a straight-line distance L2. A distance of the straight-line part23pof the branch part23lis defined as a straight-line distance L3. A hydraulic equivalent diameter of the branch part23kis defined as a hydraulic equivalent diameter De2, and a ratio of the straight-line distance L2 to the hydraulic equivalent diameter De2 is defined as a straight-line ratio L2/De2. A hydraulic equivalent diameter of the branch part23lis defined as a hydraulic equivalent diameter De3, and a ratio of the straight-line distance L3 to the hydraulic equivalent diameter De3 is defined as a straight-line ratio L3/De3.

FIG. 11is a graph showing a relationship between the straight-line ratio and the distribution ratio in the branching portion of the flow passage formed in the third plate-shaped member of the heat exchanger according to Embodiment 1. Note that,FIG. 11shows a change in distribution ratio R when the straight-line ratio L2/De2 (=L3/De3) is changed under a state in which the straight-line ratio L2/De2 is set equal to the straight-line ratio L3/De3.

As shown inFIG. 11, the distribution ratio R is changed so that the distribution ratio R is increased until the straight-line ratio L2/De2 and the straight-line ratio L3/De3 reach 1.0, and the distribution ratio R reaches 0.5 when the straight-line ratio L2/De2 and the straight-line ratio L3/De3 are 1.0 or more. When the straight-line ratio L2/De2 and the straight-line ratio L3/De3 are less than 1.0, the distribution ratio R does not become 0.5 because the branch part23kand the branch part23lare bent in different directions from the gravity direction. That is, when the straight-line ratio L2/De2 and the straight-line ratio L3/De3 are set to 1.0 or more, the uniformity in distribution of the refrigerant can be further improved.

As illustrated inFIG. 8, a bending angle of the branch part23kis defined as an angle θ1, and a bending angle of the branch part23lis defined as an angle θ2.

FIG. 12is a graph showing a relationship between the bending angle and the distribution ratio in the branching portion of the flow passage formed in the third plate-shaped member of the heat exchanger according to Embodiment 1. Note that,FIG. 12shows a change in distribution ratio R when the angle θ1 (=angleθ2) is changed under a state in which the angle θ1 is set equal to the angle θ2.

As shown inFIG. 12, as the angle θ1 and the angle θ2 approach 90 degrees, the distribution ratio R approaches 0.5. That is, when the angle θ1 and the angle θ2 are increased, the uniformity in distribution of the refrigerant can be further improved.

Usage Mode of Heat Exchanger

Now, an example of a usage mode of the heat exchanger according to Embodiment 1 is described.

Note that, in the following, there is described a case where the heat exchanger according to Embodiment 1 is used for an air-conditioning apparatus, but the present invention is not limited to such a case, and for example, the heat exchanger according to Embodiment 1 may be used for other refrigeration cycle apparatus including a refrigerant circuit. Further, there is described a case where the air-conditioning apparatus switches between a cooling operation and a heating operation, but the present invention is not limited to such a case, and the air-conditioning apparatus may perform only the cooling operation or the heating operation.

FIG. 13is a view illustrating the configuration of the air-conditioning apparatus to which the heat exchanger according to Embodiment 1 is applied. Note that, inFIG. 13, the flow of the refrigerant during the cooling operation is indicated by the solid arrow, while the flow of the refrigerant during the heating operation is indicated by the dotted arrow.

As illustrated inFIG. 13, an air-conditioning apparatus51includes a compressor52, a four-way valve53, a heat source-side heat exchanger54, an expansion device55, a load-side heat exchanger56, a heat source-side fan57, a load-side fan58, and a controller59. The compressor52, the four-way valve53, the heat source-side heat exchanger54, the expansion device55, and the load-side heat exchanger56are connected by refrigerant pipes to form a refrigerant circuit.

The controller59is connected to, for example, the compressor52, the four-way valve53, the expansion device55, the heat source-side fan57, the load-side fan58, and various sensors. The controller59switches the flow passage of the four-way valve53to switch between the cooling operation and the heating operation. The heat source-side heat exchanger54acts as a condensor during the cooling operation, and acts as an evaporator during the heating operation. The load-side heat exchanger56acts as the evaporator during the cooling operation, and acts as the condensor during the heating operation.

The flow of the refrigerant during the cooling operation is described.

The refrigerant in a high-pressure and high-temperature gas state discharged from the compressor52passes through the four-way valve53to flow into the heat source-side heat exchanger54, and is condensed through heat exchange with the outside air supplied by the heat source-side fan57, to thereby become the refrigerant in a high-pressure liquid state, which flows out from the heat source-side heat exchanger54. The refrigerant in the high-pressure liquid state flowing out from the heat source-side heat exchanger54flows into the expansion device55to become the refrigerant in a low-pressure two-phase gas-liquid state. The refrigerant in the low-pressure two-phase gas-liquid state flowing out from the expansion device55flows into the load-side heat exchanger56to be evaporated through heat exchange with indoor air supplied by the load-side fan58, to thereby become the refrigerant in a low-pressure gas state, which flows out from the load-side heat exchanger56. The refrigerant in the low-pressure gas state flowing out from the load-side heat exchanger56passes through the four-way valve53to be sucked into the compressor52.

The flow of the refrigerant during the heating operation is described.

The refrigerant in a high-pressure and high-temperature gas state discharged from the compressor52passes through the four-way valve53to flow into the load-side heat exchanger56, and is condensed through heat exchange with the indoor air supplied by the load-side fan58, to thereby become the refrigerant in a high-pressure liquid state, which flows out from the load-side heat exchanger56. The refrigerant in the high-pressure liquid state flowing out from the load-side heat exchanger56flows into the expansion device55to become the refrigerant in a low-pressure two-phase gas-liquid state. The refrigerant in the low-pressure two-phase gas-liquid state flowing out from the expansion device55flows into the heat source-side heat exchanger54to be evaporated through heat exchange with the outside air supplied by the heat source-side fan57, to thereby become the refrigerant in a low-pressure gas state, which flows out from the heat source-side heat exchanger54. The refrigerant in the low-pressure gas state flowing out from the heat source-side heat exchanger54passes through the four-way valve53to be sucked into the compressor52.

The heat exchanger1is used for at least one of the heat source-side heat exchanger54or the load-side heat exchanger56. When the heat exchanger1acts as the evaporator, the heat exchanger1is connected so that the refrigerant flows in from the stacking-type header2and the refrigerant flows out from the header3. In other words, when the heat exchanger1acts as the evaporator, the refrigerant in the two-phase gas-liquid state passes through the refrigerant pipe to flow into the stacking-type header2, and the refrigerant in the gas state passes through the first heat transfer tube4to flow into the header3. Further, when the heat exchanger1acts as the condensor, the refrigerant in the gas state passes through the refrigerant pipe to flow into the header3, and the refrigerant in the liquid state passes through the first heat transfer tube4to flow into the stacking-type header2.

Action of Heat Exchanger

Now, an action of the heat exchanger according to Embodiment 1 is described.

The second plate-shaped unit12of the stacking-type header2has the distribution flow passage12A including the branching flow passages12bformed therein. At least part of the refrigerant branched by flowing into the branching flow passage12bsequentially passes through the branch part23jand each of the branch parts23kand23l. In such a further branched state, the at least part of the refrigerant flows out from the branching flow passage12b. In other words, the refrigerant branched at the opening port23iis further branched at the branching portion23f, and hence the number of branches at the opening port23ican be reduced, which suppresses the upsize of the stacking-type header2in the entire peripheral direction perpendicular to the refrigerant inflow direction.

Further, in the stacking-type header2, the refrigerant is branched in the branching portion23ffrom the branch part23jinto the two branch parts23kand23l. Therefore, the distribution of the refrigerant is reliably uniformized. In particular, when all the opening port23iand the branching portion23fbranch the refrigerant into two flows, the distribution of the refrigerant is further reliably uniformized.

Further, in the stacking-type header2, the straight-line part23oof the branch part23kand the straight-line part23pof the branch part23lare positioned on the same straight line in the branching portion23f. The straight-line part23nof the branch part23jand each of the straight-line parts23oand23pof the branch parts23kand23lperpendicularly intersect with each other. Therefore, the refrigerant, which flows into the center23mfrom the branch part23j, flows into each of the branch parts23kand23lwithout biasing angles for changing directions, which further improves the uniformity in distribution of the refrigerant.

Further, in the stacking-type header2, the straight-line part23nof the branch part23jextends in parallel to the gravity direction, and the straight-line parts23oand23pof the branch parts23kand23lextend in a direction perpendicular to the gravity direction. Therefore, when the refrigerant branches at the center23mof the branching portion, the action of the gravity in a biased manner is suppressed, which further improves the uniformity in distribution of the refrigerant.

Further, the flow passage23A formed in the third plate-shaped member23is a through groove, and the branching flow passage12bis formed by stacking the third plate-shaped member23. Therefore, the processing and assembly are simplified, and the production efficiency, the manufacturing cost, and the like are reduced.

In particular, in the related-art stacking-type header, when the refrigerant flowing therein is in a two-phase gas-liquid state, the refrigerant is easily affected by the gravity, and it is difficult to equalize the flow rate and the quality of the refrigerant flowing into each heat transfer tube. In the stacking-type header2, however, regardless of the flow rate and the quality of the refrigerant in the two-phase gas-liquid state flowing therein, the refrigerant is less liable to be affected by the gravity, and the flow rate and the quality of the refrigerant flowing into each first heat transfer tube4can be equalized.

In particular, in the related-art stacking-type header, when the heat transfer tube is changed from a circular tube to a flat tube for the purpose of reducing the refrigerant amount or achieving space saving in the heat exchanger, the stacking-type header is required to be upsized in the entire peripheral direction perpendicular to the refrigerant inflow direction. On the other hand, the stacking-type header2is not required to be upsized in the entire peripheral direction perpendicular to the refrigerant inflow direction, and thus space saving is achieved in the heat exchanger1. In other words, in the related-art stacking-type header, when the heat transfer tube is changed from a circular tube to a flat tube, the sectional area of the flow passage in the heat transfer tube is reduced, and thus the pressure loss caused in the heat transfer tube is increased. Therefore, it is necessary to further reduce the angular interval between the plurality of grooves forming the branching flow passage to increase the number of paths (in other words, the number of heat transfer tubes), which causes upsize of the stacking-type header in the entire peripheral direction perpendicular to the refrigerant inflow direction. On the other hand, in the stacking-type header2, even when the number of paths is required to be increased, the number of the branching portions23for the number of the third plate-shaped members23is only required to be increased, and hence the upsize of the stacking-type header2in the entire peripheral direction perpendicular to the refrigerant inflow direction is suppressed. Note that, the stacking-type header2is not limited to the case where the first heat transfer tube4is a flat tube.

FIG. 14is a perspective view of Modified Example-1 of the heat exchanger according to Embodiment 1 under a state in which the stacking-type header is disassembled. Note that, inFIG. 14and subsequent figures, a state in which the both-side clad member24is stacked is illustrated (state ofFIG. 6andFIG. 7), but it is needless to say that a state in which the both-side clad member24is not stacked (state ofFIG. 2andFIG. 3) may be employed.

As illustrated inFIG. 14, the second plate-shaped member22may have the plurality of flow passages22A formed therein, in other words, the third plate-shaped member23may have the plurality of flow passages23A formed therein, to thereby reduce the number of the third plate-shaped members23. With such a configuration, the component cost, the weight, and the like can be reduced.

FIG. 15is a perspective view of Modified Example-1 of the heat exchanger according to Embodiment 1 under a state in which the stacking-type header is disassembled.

The plurality of flow passages22A may not be formed in regions opposed to refrigerant inflow regions of the flow passages23A formed in the third plate-shaped member23. As illustrated inFIG. 15, for example, the plurality of flow passages22A may be formed collectively at one position, and a flow passage25A of a different plate-shaped member25stacked between the second plate-shaped member22and the third plate-shaped member23_1may guide each of the flows of the refrigerant passing through the plurality of flow passages22A to a region opposed to the refrigerant inflow region of the flow passage23A formed in the third plate-shaped member23.

FIG. 16are a main-part perspective view and a main-part sectional view of Modified Example-2 of the heat exchanger according to Embodiment 1 under a state in which the stacking-type header is disassembled. Note that,FIG. 16(a)is a main-part perspective view under the state in which the stacking-type header is disassembled, andFIG. 16(b)is a sectional view of the third plate-shaped member23taken along the line A-A ofFIG. 16(a).

As illustrated inFIG. 16, the flow passage23A formed in the third plate-shaped member23may be a bottomed groove. In such a case, a circular through hole23ris formed at an end portion23qof a bottom surface of the groove of the flow passage23A. With such a configuration, the both-side clad member24is not required to be stacked between the plate-shaped members in order to interpose the flow passage24A functioning as the refrigerant partitioning flow passage between the branching flow passages12b, which improves the production efficiency. Note that, inFIG. 16, there is illustrated a case where the refrigerant outflow side of the flow passage23A is the bottom surface, but the refrigerant inflow side of the flow passage23A may be the bottom surface. In such a case, a through hole may be formed in a region corresponding to the opening port23i.

FIG. 17is a perspective view of Modified Example-3 of the heat exchanger according to Embodiment 1 under a state in which the stacking-type header is disassembled.

As illustrated inFIG. 17, the flow passage22A functioning as the first inlet flow passage12amay be formed in a member to be stacked other than the second plate-shaped member22, in other words, a different plate-shaped member, the both-side clad member24, or other members. In such a case, the flow passage22A may be formed as, for example, a through hole passing through the different plate-shaped member from the side surface thereof to the surface on the side on which the second plate-shaped member22is present. In other words, the present invention encompasses a configuration in which the first inlet flow passage12ais formed in the first plate-shaped unit11, and the “distribution flow passage” of the present invention encompasses distribution flow passages other than the distribution flow passage12A in which the first inlet flow passage12ais formed in the second plate-shaped unit12.

A heat exchanger according to Embodiment 2 is described.

Note that, overlapping description or similar description to that of Embodiment 1 is appropriately simplified or omitted.

Configuration of Heat Exchanger

Now, the configuration of the heat exchanger according to Embodiment 2 is described.

FIG. 18is a view illustrating the configuration of the heat exchanger according to Embodiment 2.

As illustrated inFIG. 18, the heat exchanger1includes the stacking-type header2, the plurality of first heat transfer tubes4, the retaining member5, and the plurality of fins6.

The stacking-type header2includes the refrigerant inflow port2A, the plurality of refrigerant outflow ports2B, a plurality of refrigerant inflow ports2C, and a refrigerant outflow port2D. The refrigerant pipes are connected to the refrigerant inflow port2A of the stacking-type header2and the refrigerant outflow port2D of the stacking-type header2. The first heat transfer tube4is a flat tube subjected to hair-pin bending. The plurality of first heat transfer tubes4are connected between the plurality of refrigerant outflow ports2B of the stacking-type header2and the plurality of refrigerant inflow ports2C of the stacking-type header2.

Flow of Refrigerant in Heat Exchanger

Now, the flow of the refrigerant in the heat exchanger according to Embodiment 2 is described.

The refrigerant flowing through the refrigerant pipe passes through the refrigerant inflow port2A to flow into the stacking-type header2to be distributed, and then passes through the plurality of refrigerant outflow ports2B to flow out toward the plurality of first heat transfer tubes4. In the plurality of first heat transfer tubes4, the refrigerant exchanges heat with air supplied by a fan, for example. The refrigerant passing through the plurality of first heat transfer tubes4passes through the plurality of refrigerant inflow ports2C to flow into the stacking-type header2to be joined, and then passes through the refrigerant outflow port2D to flow out toward the refrigerant pipe. The refrigerant can reversely flow.

Configuration of Laminated Header

Now, the configuration of the stacking-type header of the heat exchanger according to Embodiment 2 is described.

FIG. 19is a perspective view of the heat exchanger according to Embodiment 2 under a state in which the stacking-type header is disassembled.FIG. 20is a developed view of the stacking-type header of the heat exchanger according to Embodiment 2. Note that, inFIG. 20, the illustration of the both-side clad member24is omitted.

As illustrated inFIG. 19andFIG. 20, the stacking-type header2includes the first plate-shaped unit11and the second plate-shaped unit12. The first plate-shaped unit11and the second plate-shaped unit12are stacked on each other.

The first plate-shaped unit11has the plurality of first outlet flow passages11A and a plurality of second inlet flow passages11B formed therein. The plurality of second inlet flow passages11B correspond to the plurality of refrigerant inflow ports2C inFIG. 18.

The first plate-shaped member21has a plurality of flow passages21B formed therein. The plurality of flow passages21B are each a through hole having an inner peripheral surface shaped conforming to an outer peripheral surface of the first heat transfer tube4. When the first plate-shaped member21is stacked, the plurality of flow passages21B function as the plurality of second inlet flow passages11B.

The second plate-shaped unit12has the distribution flow passage12A and a joining flow passage12B formed therein. The joining flow passage12B includes a mixing flow passage12cand a second outlet flow passage12d. The second outlet flow passage12dcorresponds to the refrigerant outflow port2D inFIG. 18.

The second plate-shaped member22has a flow passage22B formed therein. The flow passage22B is a circular through hole. When the second plate-shaped member22is stacked, the flow passage22B functions as the second outlet flow passage12d. Note that, a plurality of flow passages22B, in other words, a plurality of second outlet flow passages12dmay be formed.

The third plate-shaped members23_1and23_2respectively have flow passages23C_1and23C_2formed therein. The flow passages23C_1and23C_2are each a rectangular through hole passing through substantially the entire region in the height direction of the third plate-shaped member23. When the third plate-shaped members23_1and23_2are stacked, each of the flow passages23C_1and23C_2functions as the mixing flow passage12c. The flow passages23C_1and23C_2may not have a rectangular shape. In the following, in some cases, the plurality of flow passages23C_1and23C_2may be collectively referred to as the flow passage23C.

In particular, it is preferred to stack the both-side clad member24having a brazing material rolled on both surfaces thereof between the respective plate-shaped members to supply the brazing material. The flow passage24B formed in the both-side clad member24_4stacked between the retaining member5and the first plate-shaped member21is a through hole having an inner peripheral surface shaped conforming to the outer peripheral surface of the first heat transfer tube4. The flow passage24B formed in the both-side clad member24_3stacked between the first plate-shaped member21and the third plate-shaped member23_2is a circular through hole. The flow passage24B formed in the both-side clad member24stacked between the third plate-shaped member23_1and the second plate-shaped member22is a rectangular through hole passing through substantially the entire region in the height direction of the both-side clad member24. When the both-side clad member24is stacked, the flow passage24B functions as the refrigerant partitioning flow passage for the second inlet flow passage11B and the joining flow passage12B.

Note that, the flow passage22B functioning as the second outlet flow passage12dmay be formed in a different plate-shaped member other than the second plate-shaped member22of the second plate-shaped unit12, the both-side clad member24, or other members. In such a case, a notch may be formed, which communicates between a part of the flow passage23C or the flow passage24B and, for example, a side surface of the different plate-shaped member or the both-side clad member24. The mixing flow passage12cmay be turned back so that the flow passage22B functioning as the second outlet flow passage12dis formed in the first plate-shaped member21. In other words, the present invention encompasses a configuration in which the second outlet flow passage12dis formed in the first plate-shaped unit11, and the “joining flow passage” of the present invention encompasses joining flow passages other than the joining flow passage12B in which the second outlet flow passage12dis formed in the second plate-shaped unit12.

Flow of Refrigerant in Laminated Header

Now, the flow of the refrigerant in the stacking-type header of the heat exchanger according to Embodiment 2 is described.

As illustrated inFIG. 19andFIG. 20, the refrigerant flowing out from the flow passage21A of the first plate-shaped member21to pass through the first heat transfer tube4flows into the flow passage21B of the first plate-shaped member21. The refrigerant flowing into the flow passage21B of the first plate-shaped member21flows into the flow passage23C formed in the third plate-shaped member23to be mixed. The mixed refrigerant passes through the flow passage22B of the second plate-shaped member22to flow out therefrom toward the refrigerant pipe.

Usage Mode of Heat Exchanger

Now, an example of a usage mode of the heat exchanger according to Embodiment 2 is described.

FIG. 21is a diagram illustrating a configuration of an air-conditioning apparatus to which the heat exchanger according to Embodiment 2 is applied.

As illustrated inFIG. 21, the heat exchanger1is used for at least one of the heat source-side heat exchanger54or the load-side heat exchanger56. When the heat exchanger1acts as the evaporator, the heat exchanger1is connected so that the refrigerant passes through the distribution flow passage12A of the stacking-type header2to flow into the first heat transfer tube4, and the refrigerant passes through the first heat transfer tube4to flow into the joining flow passage12B of the stacking-type header2. In other words, when the heat exchanger1acts as the evaporator, the refrigerant in a two-phase gas-liquid state passes through the refrigerant pipe to flow into the distribution flow passage12A of the stacking-type header2, and the refrigerant in a gas state passes through the first heat transfer tube4to flow into the joining flow passage12B of the stacking-type header2. Further, when the heat exchanger1acts as the condensor, the refrigerant in a gas state passes through the refrigerant pipe to flow into the joining flow passage12B of the stacking-type header2, and the refrigerant in a liquid state passes through the first heat transfer tube4to flow into the distribution flow passage12A of the stacking-type header2.

Action of Heat Exchanger

Now, the action of the heat exchanger according to Embodiment 2 is described.

In the stacking-type header2, the first plate-shaped unit11has the plurality of second inlet flow passages11B formed therein, and the second plate-shaped unit12has the joining flow passage12B formed therein. Therefore, the header3is unnecessary, and thus the component cost and the like of the heat exchanger1are reduced. Further, the header3is unnecessary, and accordingly, it is possible to extend the first heat transfer tube4to increase the number of the fins6and the like, in other words, increase the mounting volume of the heat exchanging unit of the heat exchanger1.

A heat exchanger according to Embodiment 3 is described.

Note that, overlapping description or similar description to that of each of Embodiment 1 and Embodiment 2 is appropriately simplified or omitted.

Configuration of Heat Exchanger

Now, the configuration of the heat exchanger according to Embodiment 3 is described.

FIG. 22is a view illustrating the configuration of the heat exchanger according to Embodiment 3.

As illustrated inFIG. 22, the heat exchanger1includes the stacking-type header2, the plurality of first heat transfer tubes4, a plurality of second heat transfer tubes7, the retaining member5, and the plurality of fins6.

The stacking-type header2includes a plurality of refrigerant turn-back ports2E. Similarly to the first heat transfer tube4, the second heat transfer tube7is a flat tube subjected to hair-pin bending. The plurality of first heat transfer tubes4are connected between the plurality of refrigerant outflow ports2B and the plurality of refrigerant turn-back ports2E of the stacking-type header2, and the plurality of second heat transfer tubes7are connected between the plurality of refrigerant turn-back ports2E and the plurality of refrigerant inflow ports2C of the stacking-type header2.

Flow of Refrigerant in Heat Exchanger

Now, the flow of the refrigerant in the heat exchanger according to Embodiment 3 is described.

The refrigerant flowing through the refrigerant pipe passes through the refrigerant inflow port2A to flow into the stacking-type header2to be distributed, and then passes through the plurality of refrigerant outflow ports2B to flow out toward the plurality of first heat transfer tubes4. In the plurality of first heat transfer tubes4, the refrigerant exchanges heat with air supplied by a fan, for example. The refrigerant passing through the plurality of first heat transfer tubes4flows into the plurality of refrigerant turn-back ports2E of the stacking-type header2to be turned back, and flows out therefrom toward the plurality of second heat transfer tubes7. In the plurality of second heat transfer tubes7, the refrigerant exchanges heat with air supplied by a fan, for example. The flows of the refrigerant passing through the plurality of second heat transfer tubes7pass through the plurality of refrigerant inflow ports2C to flow into the stacking-type header2to be joined, and the joined refrigerant passes through the refrigerant outflow port2D to flow out therefrom toward the refrigerant pipe. The refrigerant can reversely flow.

Configuration of Laminated Header

Now, the configuration of the stacking-type header of the heat exchanger according to Embodiment 3 is described.

FIG. 23is a perspective view of the heat exchanger according to Embodiment 3 under a state in which the stacking-type header is disassembled.FIG. 24is a developed view of the stacking-type header of the heat exchanger according to Embodiment 3. Note that, inFIG. 24, the illustration of the both-side clad member24is omitted.

As illustrated inFIG. 23andFIG. 24, the stacking-type header2includes the first plate-shaped unit11and the second plate-shaped unit12. The first plate-shaped unit11and the second plate-shaped unit12are stacked on each other.

The first plate-shaped unit11has the plurality of first outlet flow passages11A, the plurality of second inlet flow passages11B, and a plurality of turn-back flow passages11C formed therein. The plurality of turn-back flow passages11C correspond to the plurality of refrigerant turn-back ports2E inFIG. 22.

The first plate-shaped member21has a plurality of flow passages21C formed therein. The plurality of flow passages21C are each a through hole having an inner peripheral surface shaped to surround the outer peripheral surface of the end portion of the first heat transfer tube4on the refrigerant outflow side and the outer peripheral surface of the end portion of the second heat transfer tube7on the refrigerant inflow side. When the first plate-shaped member21is stacked, the plurality of flow passages21C function as the plurality of turn-back flow passages11C.

In particular, it is preferred to stack the both-side clad member24having a brazing material rolled on both surfaces thereof between the respective plate-shaped members to supply the brazing material. The flow passage24C formed in the both-side clad member24_4stacked between the retaining member5and the first plate-shaped member21is a through hole having an inner peripheral surface shaped to surround the outer peripheral surface of the end portion of the first heat transfer tube4on the refrigerant outflow side and the outer peripheral surface of the end portion of the second heat transfer tube7on the refrigerant inflow side. When the both-side clad member24is stacked, the flow passage24C functions as the refrigerant partitioning flow passage for the turn-back flow passage11C.

Flow of Refrigerant in Laminated Header

Now, the flow of the refrigerant in the stacking-type header of the heat exchanger according to Embodiment 3 is described.

As illustrated inFIG. 23andFIG. 24, the refrigerant flowing out from the flow passage21A of the first plate-shaped member21to pass through the first heat transfer tube4flows into the flow passage21C of the first plate-shaped member21to be turned back and flow into the second heat transfer tube7. The refrigerant passing through the second heat transfer tube7flows into the flow passage21B of the first plate-shaped member21. The refrigerant flowing into the flow passage21B of the first plate-shaped member21flows into the flow passage23C formed in the third plate-shaped member23to be mixed. The mixed refrigerant passes through the flow passage22B of the second plate-shaped member22to flow out therefrom toward the refrigerant pipe.

Usage Mode of Heat Exchanger

Now, an example of a usage mode of the heat exchanger according to Embodiment 3 is described.

FIG. 25is a diagram illustrating a configuration of an air-conditioning apparatus to which the heat exchanger according to Embodiment 3 is applied.

As illustrated inFIG. 25, the heat exchanger1is used for at least one of the heat source-side heat exchanger54or the load-side heat exchanger56. When the heat exchanger1acts as the evaporator, the heat exchanger1is connected so that the refrigerant passes through the distribution flow passage12A of the stacking-type header2to flow into the first heat transfer tube4, and the refrigerant passes through the second heat transfer tube7to flow into the joining flow passage12B of the stacking-type header2. In other words, when the heat exchanger1acts as the evaporator, the refrigerant in a two-phase gas-liquid state passes through the refrigerant pipe to flow into the distribution flow passage12A of the stacking-type header2, and the refrigerant in a gas state passes through the second heat transfer tube7to flow into the joining flow passage12B of the stacking-type header2. Further, when the heat exchanger1acts as the condensor, the refrigerant in a gas state passes through the refrigerant pipe to flow into the joining flow passage12B of the stacking-type header2, and the refrigerant in a liquid state passes through the first heat transfer tube4to flow into the distribution flow passage12A of the stacking-type header2.

Further, when the heat exchanger1acts as the condensor, the heat exchanger1is arranged so that the first heat transfer tube4is positioned on the upstream side (windward side) of the air stream generated by the heat source-side fan57or the load-side fan58with respect to the second heat transfer tube7. In other words, there is obtained a relationship that the flow of the refrigerant from the second heat transfer tube7to the first heat transfer tube4and the air stream are opposed to each other. The refrigerant of the first heat transfer tube4is lower in temperature than the refrigerant of the second heat transfer tube7. The air stream generated by the heat source-side fan57or the load-side fan58is lower in temperature on the upstream side of the heat exchanger1than on the downstream side of the heat exchanger1. As a result, in particular, the refrigerant can be subcooled (so-called subcooling) by the low-temperature air stream flowing on the upstream side of the heat exchanger1, which improves the condensor performance. Note that, the heat source-side fan57and the load-side fan58may be arranged on the windward side or the leeward side.

Action of Heat Exchanger

Now, the action of the heat exchanger according to Embodiment 3 is described.

In the heat exchanger1, the first plate-shaped unit11has the plurality of turn-back flow passages11C formed therein, and in addition to the plurality of first heat transfer tubes4, the plurality of second heat transfer tubes7are connected. For example, it is possible to increase the area in a state of the front view of the heat exchanger1to increase the heat exchange amount, but in this case, the housing that incorporates the heat exchanger1is upsized. Further, it is possible to decrease the interval between the fins6to increase the number of the fins6, to thereby increase the heat exchange amount. In this case, however, from the viewpoint of drainage performance, frost formation performance, and anti-dust performance, it is difficult to decrease the interval between the fins6to less than about 1 mm, and thus the increase in heat exchange amount may be insufficient. On the other hand, when the number of rows of the heat transfer tubes is increased as in the heat exchanger1, the heat exchange amount can be increased without changing the area in the state of the front view of the heat exchanger1, the interval between the fins6, or other matters. When the number of rows of the heat transfer tubes is two, the heat exchange amount is increased about 1.5 times or more. Note that, the number of rows of the heat transfer tubes may be three or more. Still further, the area in the state of the front view of the heat exchanger1, the interval between the fins6, or other matters may be changed.

Further, the header (stacking-type header2) is arranged only on one side of the heat exchanger1. For example, when the heat exchanger1is arranged in a bent state along a plurality of side surfaces of the housing incorporating the heat exchanger1in order to increase the mounting volume of the heat exchanging unit, the end portion may be misaligned in each row of the heat transfer tubes because the curvature radius of the bent part differs depending on each row of the heat transfer tubes. When, as in the stacking-type header2, the header (stacking-type header2) is arranged only on one side of the heat exchanger1, even when the end portion is misaligned in each row of the heat transfer tubes, only the end portions on one side are required to be aligned, which improves the degree of freedom in design, the production efficiency, and other matters as compared to the case where the headers (stacking-type header2and header3) are arranged on both sides of the heat exchanger1as in the heat exchanger according to Embodiment 1. In particular, the heat exchanger1can be bent after the respective members of the heat exchanger1are joined to each other, which further improves the production efficiency.

Further, when the heat exchanger1acts as the condensor, the first heat transfer tube4is positioned on the windward side with respect to the second heat transfer tube7. When the headers (stacking-type header2and header3) are arranged on both sides of the heat exchanger1as in the heat exchanger according to Embodiment 1, it is difficult to provide a temperature difference in the refrigerant for each row of the heat transfer tubes to improve the condensor performance. In particular, when the first heat transfer tube4and the second heat transfer tube7are flat tubes, unlike a circular tube, the degree of freedom in bending is low, and hence it is difficult to realize providing the temperature difference in the refrigerant for each row of the heat transfer tubes by deforming the flow passage of the refrigerant. On the other hand, when the first heat transfer tube4and the second heat transfer tube7are connected to the stacking-type header2as in the heat exchanger1, the temperature difference in the refrigerant is inevitably generated for each row of the heat transfer tubes, and obtaining the relationship that the refrigerant flow and the air stream are opposed to each other can be easily realized without deforming the flow passage of the refrigerant.

The present invention has been described above with reference to Embodiment 1 to Embodiment 3, but the present invention is not limited to those embodiments. For example, a part or all of the respective embodiments, the respective modified examples, and the like may be combined.

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