Heat Exchanger

This is a continuation application of International Patent Application No. PCT/JP2023/039233, filed Oct. 31, 2023, and claims priority to Japanese Patent Application No. 2023-001053, filed Jan. 6, 2023. The contents of these priority applications are incorporated herein by reference.

The present disclosure relates to a heat exchanger.

In a conventional heat exchanger that exchanges heat between a refrigerant flowing in the heat exchanger and air uses an aluminum member extruded into a shape having an Ω-shaped cross section as described in PTL 1 (International Publication No. WO2016/152127) in some cases. An aluminum elongated member having an Ω-shaped cross section described in PTL 1 is used as a component of a header tank.

A heat exchanger of a first aspect includes a header and a plurality of multi-hole heat transfer tubes. The header extends in a first direction and has an inside where a refrigerant flows. The plurality of multi-hole heat transfer tubes are inserted into the header in a second direction intersecting the first direction, each of the multi-hole heat transfer tubes having a width in a third direction intersecting the first direction larger than a height in the first direction at a portion inserted into the header and including a plurality of holes communicating with the inside of the header. The header includes a first member that includes a first opening extending in the first direction and having an Ω-shaped cross section perpendicular to the first direction, a second member that includes a plurality of second openings each having a larger width than the first opening in the third direction, and a third member that includes a plurality of third openings each having a larger width than the plurality of second openings in the third direction and communicating with the plurality of multi-hole heat transfer tubes, and with which the plurality of multi-hole heat transfer tubes are in contact. The first member, the second member, and the third member are disposed in the order of the first member, the second member, and the third member, and are joined such that each of the second openings overlaps each of the third openings within a range of a width of each of the third openings in the third direction, and the first opening overlaps each of the second openings within a range of a width of each of the second openings in the third direction.

In the heat exchanger of the first aspect, the stress concentration at the joint portion between the multi-hole heat transfer tube and the header can be alleviated by the second member, thus improving the pressure resistance strength of the heat exchanger.

Hereinafter, a heat exchanger according to one or more embodiments will be described. A first direction drshown in the drawings is a direction in which a headerextends (i.e., header extension direction), and a second direction dris a direction intersecting the first direction dr. Here, a case where the first direction drand the second direction drare orthogonal to each other will be described. A multi-hole heat transfer tubeis inserted into the headerin the second direction dr(i.e., heat transfer tube insertion direction). A third direction dris a direction intersecting both the first direction drand the second direction dr. Here, a case where the third direction dris orthogonal to the first direction drand the second direction drwill be described. The third direction dris a width direction of the multi-hole heat transfer tubeat a portion where the multi-hole heat transfer tubeis inserted into the header(i.e., heat transfer tube width direction). The third direction dris a direction in which a fluid, as an object of heat exchange with a refrigerant, passes through the heat exchangerat a portion where the multi-hole heat transfer tubeis inserted into the header. The fluid as an object of heat exchange is, for example, air. For example, in a case where the first direction dris a vertical direction, the second direction drand the third direction drare horizontal directions. In the following description, the expression “extending in a direction” or “arranged in a direction” includes not only the case where the extending direction or the arranged direction of an extending object coincides with either of the above-described directions, but also the case where the smaller angle between the extending direction or the arranged direction of the object and the above-described direction is equal to or smaller than 45 degrees. For example, a case where the multi-hole heat transfer tubeextending linearly extends at an inclination of 45 degrees with respect to the second direction dralso corresponds to a case where the multi-hole heat transfer tubeextends in the second direction dr. In addition, a case where the multi-hole heat transfer tubeis curved also corresponds to a case where the multi-hole heat transfer tubeextends in the second direction drif the inclination of the tangent line with respect to the second direction dris equal to or smaller than 45 degrees.

shows the heat exchangeras viewed in the third direction dr.shows the heat exchangeras viewed in the first direction dr. The heat exchangeris, for example, an air heat exchanger that exchanges heat between a refrigerant and air. A refrigeration cycle apparatus including the heat exchangeris used for, for example, air-conditioning. For example, the heat exchangeris applied to a refrigeration cycle apparatus that performs a refrigeration cycle in which a refrigerant is brought into a supercritical state. The heat exchangercan be used as an evaporator for evaporating a refrigerant or a radiator for radiating heat from a refrigerant in the refrigeration cycle apparatus. The radiator here includes a condenser for condensing a refrigerant. The refrigerant heat-exchanged in the heat exchangeris, for example, a high-pressure refrigerant having a high pressure of 4.5 MPa or more in the heat exchanger. The high-pressure refrigerant is, for example, carbon dioxide.

The heat exchangerincludes a plurality of headers, a plurality of multi-hole heat transfer tubes, and a plurality of fins. To distinguish the plurality of headersfrom each other, one of them is referred to as a first header, and the other is referred to as a second header. The headerhas a main body internal space Sthat is a long hollow portion extending in the first direction dr. The refrigerant flows through the main body internal space S. Here, the cross-sectional shape of the main body internal space Staken along a plane orthogonal to the first direction dris a combination of a circular shape and a small rectangular shape. The cross-sectional shape of the main body internal space Sis not necessarily a combination of a circular shape and a small rectangular shape, and may be a combination of an elliptical shape and a trapezoidal shape, for example. However, the sectional shape of the main body internal space Smay be a combination of a circular shape and another shape in order to avoid concentration of stress applied to the headerfrom a refrigerant.

The first headerdistributes a refrigerant to the plurality of multi-hole heat transfer tubes, and the second headermerges the refrigerant flowing out from the plurality of multi-hole heat transfer tubes. A refrigerant sent from another device to the heat exchangerflows into the first header. The refrigerant merged in the second headeris sent from the heat exchangerto another device. Therefore, an inlet pipe (not shown) through which the refrigerant sent to the heat exchangerpasses is connected to the first header, and an outlet pipe (not shown) through which the refrigerant sent out from the heat exchangerpasses is connected to the second header.

In the heat exchangershown in, one end and the other end of ten or more multi-hole heat transfer tubesare respectively inserted into the two headers(first headerand second header). Here, the multi-hole heat transfer tubesare inserted into the headerso that the multi-hole heat transfer tubesare orthogonal to the header. However, the multi-hole heat transfer tubesare not necessarily inserted so as to be orthogonal to the header, and an angle formed by the multi-hole heat transfer tubesand the headercan be set to any angle. Each multi-hole heat transfer tubeextends between the two headers. In other words, the two headersand a large number of the multi-hole heat transfer tubesare assembled in a shelf form. Here, each of the multi-hole heat transfer tubesis arranged so as to be parallel to other adjacent multi-hole heat transfer tubes. However, the multi-hole heat transfer tubesadjacent to each other are not necessarily arranged in parallel to each other, and the positional relationship between the adjacent multi-hole heat transfer tubescan be set to any form. Here, ten or more multi-hole heat transfer tubesare arranged side by side at equal intervals. However, the multi-hole heat transfer tubesare not necessarily arranged at equal intervals, and may be arranged side by side at irregular intervals, for example.

shows a heat exchanging partincluding a plurality of multi-hole heat transfer tubesand a plurality of fins. The heat exchanging partwill be described later in detail.shows a section of the headertaken along line I-I in. As shown inand, one multi-hole heat transfer tubehas a plurality of holesthat are flow paths of a refrigerant. Each multi-hole heat transfer tubehas a width of a length LA and a thickness of a length LB. Each multi-hole heat transfer tubeis manufactured by, for example, extrusion. The multi-hole heat transfer tubeis made of, for example, aluminum or an aluminum alloy. Here, the third direction drcoincides with the width direction of the multi-hole heat transfer tube. Here, the plurality of holesextend in the second direction drand are arranged in the third direction dr. Here, the plurality of holesare arranged parallel to each other at equal intervals. The main body internal space Sof the headercommunicates with the plurality of holesof the multi-hole heat transfer tube. A refrigerant flows out from the main body internal space Sof the first headerto the plurality of holesof the plurality of multi-hole heat transfer tubes. The refrigerant flows into the main body internal space Sof the second headerfrom the plurality of holesof the plurality of multi-hole heat transfer tubes. The refrigerant flowing through the plurality of holesof the multi-hole heat transfer tubeexchanges heat with the air passing on the surface of the multi-hole heat transfer tube.

The finis a member that accelerates heat exchange between the refrigerant flowing through the holesof the multi-hole heat transfer tubeand the air passing through the heat exchanger. The plurality of finsincrease a heat transfer area of the heat exchangerfor the air passing through the heat exchanger. Each finis formed by deforming a thin plate-shaped member by press working or the like. The finis made of, for example, aluminum or an aluminum alloy. Each finextends in the first direction dr. Here, the plurality of finsare arranged side by side at equal intervals in the second direction dr. However, the finsare not necessarily arranged at equal intervals, and may be arranged side by side at irregular intervals, for example. Each finis thermally connected to the plurality of multi-hole heat transfer tubes. Each multi-hole heat transfer tubeis thermally connected to the plurality of fins. The plurality of multi-hole heat transfer tubesare inserted into a plurality of notchesof each fin, whereby the plurality of multi-hole heat transfer tubesand each finare in contact with each other directly or via a brazing material, and are thermally connected to each other. The heat exchangeris manufactured, for example, by furnace brazing.

The plurality of multi-hole heat transfer tubesand the plurality of finsbetween the first headerand the second headerof the heat exchangerfunction as the heat exchanging part. The heat exchange performed in the heat exchangeris mainly performed in the heat exchanging part. The shape of the heat exchanging partshown inis configured to extend in the first direction drand the second direction dr. In other words, the heat exchanging partinhas an I-shape when viewed in the first direction dr. However, the shape of the heat exchanging partis not limited to the shape shown in. The shape of the heat exchanging partmay be, for example, a shape that extends in the second direction drwhen viewed in the first direction drand then curves to extend in the third direction dr. For example, the heat exchanging partmay have an L-shape, a U-shape, or a polygonal shape when viewed in the first direction dr. The shape of the heat exchanging partmay be such that the flow of air passing through the heat exchanging partis limited to one direction, or may be such that the flow of air passing through the heat exchanging partis directed in multiple directions.

shows the headerdisassembled into components and viewed obliquely.shows the shape of a cross section of the headerperpendicular to the longitudinal direction (first direction dr). In the following description of the header, the terms “first header” and “second header” are used only in a case where the first headerand the second headerneed to be distinguished from each other.

The headerincludes a first memberwhich is a main body member, a second memberwhich is a reinforcing member, a third memberwhich is a stiffening plate member, a fourth memberwhich is an insertion margin adjusting member, and a fifth memberwhich is a support. Although not shown in, the headeralso includes closing plates disposed at both ends of the headerin the first direction dr. The closing plates are attached to attachment holesof the fifth member. The closing plates attached to the attachment holesof the fifth memberclose both ends of the main body internal space S. In the header, the first member, the second member, the third member, the fourth member, and the fifth memberare joined together. The joining in the headeris, for example, fixing of members to each other by brazing. For example, the fifth memberis a cladding member, and a brazing material is supplied from the fifth memberto the first member, the second member, the third member, and the fourth member, whereby the members can be fixed to each other by brazing. For example, a cladding member may be used for all or some of the second member, the third member, and the fourth memberother than the fifth member. Moreover, a brazing material may be supplied from other than the second member, the third member, the fourth member, and the fifth member, for example. Further, here, the first member, the second member, the third member, and the fourth memberare fixed by being physically held by a claw portionof the fifth member. Although the fixing by the claw portioncan be omitted, the fixing by the claw portionmay also be performed in order to withstand the use of the high-pressure refrigerant. However, the physical fixing method is not limited to the holding by the claw portion.

In a case where the fifth memberis a cladding member, the first member, the second member, the third member, and the fourth membercan be joined to each other even if they are made of, for example, aluminum or an aluminum alloy. In a case where the fifth memberis a cladding member, a member in which a portion excluding the brazing material is made of aluminum or an aluminum alloy, for example, can be used as the fifth member. In this way, in a case where aluminum or an aluminum alloy is used for the header, the pressure of a refrigerant may be set to smaller thanMPa. The first memberis formed by extrusion. In the extrusion, the first memberis formed by being extruded so that the cross-sectional shape is Ω-shaped. The first memberformed by such extrusion is an extruded member. Each of the second member, the third member, the fourth member, and the fifth memberis formed by, for example, pressing a metal plate. Here, the press working is processing of punching a metal plate to form a hole or bending a metal plate by a press machine.

shows a cross-sectional shape of the first membertaken along a plane extending in the second direction drand the third direction dr. Moreover,shows a state where the first memberin which the multi-hole heat transfer tubesare fitted is cut along a plane extending in the second direction drand the third direction dr. Since the first memberextends in the first direction dr, the longitudinal direction of the first membercoincides with the first direction dr. As shown inand, the main body internal space Sof the first memberincludes a columnar space Sthat is a portion having a circular cross-section and a first opening Othat is a portion having a rectangular cross-section. The columnar space Sand the first opening Oare connected to each other, and both the columnar space Sand the first opening Oextend in the first direction dr. The first memberincludes a cylindrical portionaround the columnar space S, and two flat plate portionsprotruding from the cylindrical portionin the third direction dr. In other words, the flat plate portionsextend in the first direction drand the third direction dr. A cross section of the cylindrical portionand the two flat plate portionstaken along a plane perpendicular to the first direction dris an Ω-shape.

The first opening Ohas a width Win the third direction dr. The width Wof the first openings Ois set, for example, within a range of 0.8 mm≤W≤2.0 mm. The first opening Ohas a length Lin the second direction dr. The first opening Ois an opening communicating with the holesof the multi-hole heat transfer tube. Each flat plate portionhas a thickness Tin the second direction dr. The thickness Tof the flat plate portionis set, for example, within a range of 2 mm≤T≤4.5 mm. In order to reduce a pressure receiving area of the first opening O, the length Lof the first opening Ois set to be smaller than the thickness Tof the flat plate portion.

The second member, which is a reinforcing member, is a flat plate having a plurality of second openings Oarranged in the first direction dr. The second member, which is a reinforcing member, has a function of alleviating the stress concentration occurring around the joint portion between the headerand the multi-hole heat transfer tube. The second memberand the flat plate portionsof the first memberare brazed to each other at the surfaces of the second memberand the flat plate portionsextending in the first direction drand the third direction dr. The thickness Tof the second memberis set, for example, within a range of 2 mm≤T≤4.5 mm. The second memberis manufactured by, for example, processing a metal flat plate of aluminum or an aluminum alloy by press working. In a case where the thickness Tis in the above-described range, the second membercan be easily processed by press working. The second membercan be formed by punching out the portion of the second openings Ofrom a metal flat plate by press working.

Each second opening Ohas a width Win the third direction dr. The second opening Ohas an oval shape obtained by connecting two semi-circles with straight lines. In order to form the second opening Oby press working, the width Wof the second opening Omay be 1.5 times or more the thickness T. If the thickness Tis 2 mm≤T≤4.5 mm, for example, the width Wof the second opening Ois set within a range of 3 mm≤W≤6.75 mm. In order to obtain a high pressure resistance strength, the width Wof the second opening Omay be narrow, and may be equal to or less than 10 mm. In order to prevent the first opening Ofrom being blocked by the brazing material during brazing, the width Wof the second opening Omay be set to be equal to or more than the length obtained by adding a length of the brazing material protruding from the end of the second opening O(for example, equal to or more than 0.8 mm and equal to or less than 2 mm) to the width Wof the first opening O. For example, if the width Wof the first opening Ois 1.6 mm, the width Wof the second opening Omay be set within a range of 3.2 mm≤W≤5.6 mm in consideration of the pressure resistance strength and the protrusion of the brazing material.

The length Lof the second openings Oin the first direction dris, for example, longer than the length LB of the multi-hole heat transfer tubein the first direction drand shorter than twice the length LB (LB≤L≤{LB×2}).

The third member, which is a stiffening plate member, is a flat plate having a plurality of third openings Oarranged in the first direction dr. Each third opening Ois oval. The third member, which is a stiffening plate member, is a member that is in contact with the distal ends of the multi-hole heat transfer tubesfitted to the headerto allow all the holesto communicate with the first opening O. Surfaces of the second memberand the third memberextending in the first direction drand the third direction drare brazed to each other. The thickness Tof the third memberis set, for example, within a range of 2 mm≤T≤4.5 mm. The third memberis manufactured by, for example, processing a metal flat plate of aluminum or an aluminum alloy by press working. If the thickness Tis in the above-described range, the third membercan be easily processed by press working. The third membercan be formed by punching out the portion of the third openings Ofrom the metal flat plate by press working. Each third opening Ohas a width Win the third direction dr.

In order to form the third opening Oby press working, the width Wof the third opening Wmay be 1.5 times or more the thickness T. The width Wof the third opening Ois set to be shorter than the length LA of the multi-hole heat transfer tube. However, in order to allow all the holesof the multi-hole heat transfer tubeto communicate with the third opening O, the width Wis set such that the ends of the third opening Oare located outside the width W(see) including the outermost holes. In order to obtain a high pressure resistance strength, the width Wof the third opening Omay be narrow. In order to prevent the second opening Ofrom being narrowed by the brazing material during brazing, the width Wof the third opening Omay be set to equal to or more than the length obtained by adding a length of the brazing material protruding from the ends of the third opening O(for example, equal to or more than 0.8 mm and equal to or less than 2 mm) to the width Wof the second opening O. In addition, the length from the holeof the multi-hole heat transfer tubeto the end of the third opening Omay be longer than the protruding length of the brazing material.

The length Lof the third openings Oin the first direction dris, for example, longer than the length LB of the multi-hole heat transfer tubein the first direction drand shorter than three times the length LB (LB≤L≤{LB×3}).

The fourth member, which is an insertion margin adjusting member, is a flat plate having a plurality of fourth openings Oarranged in the first direction dr. Each fourth opening Ois oval. The fourth member, which is an insertion margin adjusting member, is a member for determining the length (insertion margin) from the fifth member, which is a support, to the distal end of the header. Surfaces of the third memberand the fourth memberextending in the first direction drand the third direction drare brazed to each other. The multi-hole heat transfer tubeis brazed to the inner surface of the fourth opening O. The thickness Tof the fourth memberis set, for example, within a range of 2 mm≤T≤4.5 mm. The fourth memberis manufactured by, for example, processing a metal flat plate of aluminum or an aluminum alloy by press working. If the thickness Tis in the above-described range, the fourth membercan be easily processed by press working. The fourth membercan be formed by punching out the portion of the fourth openings Ofrom the metal flat plate by press working.

Each fourth opening Ohas a width Win the third direction dr. In order to form the fourth opening Oby press working, the width Wof the fourth opening Omay be 1.5 times or more the thickness T. The width Wof the fourth opening Ois set to be longer than the length LA of the multi-hole heat transfer tube. The width Wof the fourth opening Omay be close to the length LA of the multi-hole heat transfer tubeso that side surfacesof the multi-hole heat transfer tubeand the inner surface of the fourth opening Oare brazed to each other.

The length Lof the fourth opening Oin the first direction dris, for example, longer than the length LB of the multi-hole heat transfer tubein the first direction drand shorter than three times the length LB (LB≤L≤{LB×}).

The fifth member, which is a support, has a plurality of fifth openings Oarranged in the first direction dr. Each fifth opening Ois oval. The fifth memberhas a shape in which both ends of a flat plate in the third direction drare bent in the second direction dr. Thus, a cross section of the fifth membertaken along a plane orthogonal to the first direction dris C-shaped. With the C-shape, the fifth membercan be in contact with the flat plate portionsof the first member, the second member, and the third member. The fifth memberincludes a heat transfer tube support portionin which a plurality of fifth openings Oare formed, and a first side portionand a second side portionthat are in contact with the flat plate portionsof the first member, the second member, and the third member(see). The heat transfer tube support portion, the first side portion, and the second side portioneach have a flat plate shape.

The fifth member, which is a support, is a member that supports the multi-hole heat transfer tubefitted in the fifth opening Oby the inner surface of the fifth opening O. The entire inner surface of the fifth opening Ois brazed to the outer peripheral surface of the multi-hole heat transfer tube. Such brazing prevents a refrigerant from leaking from the boundary between the fifth memberand the multi-hole heat transfer tube. Surfaces of the fourth memberand the heat transfer tube support portionof the fifth memberextending in the first direction drand the third direction drare brazed to each other. The first side portionis brazed to one side surfaceof the flat plate portionof the first member, one side surfaceof the second member, one side surfaceof the third member, and one side surfaceof the fourth member. Similarly, the second side portionis brazed to the other side surfaceof the flat plate portionof the first member, the other side surfaceof the second member, the other side surfaceof the third member, and the other side surfaceof the fourth member.

The thickness Tof the fifth memberis set, for example, within a range of 2 mm≤T≤4.5 mm. The fifth memberis manufactured by, for example, processing a metal flat plate of aluminum or an aluminum alloy by press working. If the thickness Tis in the above-described range, the fifth membercan be easily processed by press working. The fifth membercan be formed by punching out the portion of the fifth openings Oand the portion of an attachment holefrom the metal flat plate by press working, and then bending the portions corresponding to the first side portionand the second side portionby press working.

Each fifth opening Ohas a width Win the third direction dr. In order to form the fifth opening Oby press working, the width Wof the fifth opening Omay be equal to or more than 1.5 times the thickness T. The width Wof the fifth opening Ois set to coincide with the length LA of the multi-hole heat transfer tube. However, the outer shape of the multi-hole heat transfer tubeis set to be slightly smaller than the shape of the fifth opening Oso that the multi-hole heat transfer tubeis smoothly inserted into the fifth opening Owhen the multi-hole heat transfer tubeis assembled. Therefore, the length Lof the fifth opening Oin the first direction drcoincides with the length LB of the multi-hole heat transfer tubein the first direction dr.

In order to prevent the width Wof the first opening Oof the first memberfrom being blocked by brazing, the width Wof the second opening Oof the second membermay be equal to or larger than a value obtained by adding twice the protruding length Lα of the brazing material (Lα×2) to the width W. For example, in a case where the width Oof the first opening Wis 1.6 mm and the protruding length La of the brazing material is 0.8 mm to 2 mm, the width Wof the second opening Omay be set to 3.2 mm to 5.6 mm or more. From the viewpoint of brazing, the ratio between Wand Wmay be set so as to be 2/1≤W/Wif the width Wis 3.2 mm, and so as to be 3.5/1≤W/Wif the width Wis 5.6 mm. If the width Wof each second opening Ois larger than twice the width Wof the first opening O, the first opening Ois less likely to be narrowed by brazing when the first memberand the second memberare brazed. In addition, even if the first memberand the second memberare misaligned and brazed at the time of manufacturing, it is possible to prevent the first opening Ofrom being narrowed by the second member.

As the second member, which is a reinforcing member, a metal plate made of aluminum or an aluminum alloy having a plate thickness (thickness) of 2 mm to 4.5 mm is usually used. In order to press such a second member, the width Wmay be 1.5 times or more the plate thickness of the metal plate. Therefore, in general, the width Wmay be set to be equal to or more than 3 mm if the plate thickness is 2 mm, and may be set to be equal to or more than 6.75 mm if the plate thickness is 4.5 mm. From the viewpoint of the relationship between the plate thickness of the metal plate and the width W, the ratio between Wand Wmay be set so as to be, for example, 1.88/1≤W/Wif the width Wof the first opening Ois 1.6 mm and the plate thickness is 2 mm, and so as to be 4.2/1≤W/Wif the plate thickness is 4.5 mm.

From the viewpoint of the pressure resistance strength, the width Wof the second openings Omay be equal to or less than 10 mm. Therefore, if the width Wof the first opening Ois 1.6 mm, for example, the ratio between Wand Wmay be set so as to be W/W≤6.25/1.

With the consideration as described above on the width Wof the first opening Othat is usually used, the width Wmay satisfy the condition of 2/1≤W/W≤6/1, and the width Wmay further satisfy the condition of 2.5/1≤W/W≤4/1.

The width Wof each third opening Oin the third direction is larger than twice the width Wof each second opening Oin the third direction. In other words, the width Wof each second opening Ois smaller than half the width Wof each third opening O(W/W≤1/2). With the setting satisfying W/W≤/, it is possible to suppress deterioration of the reinforcing effect of the second member, as compared with a case where the width Wof each second opening Ois larger than half the width Wof each third opening O. For example, when the width Wof the third opening Ois the same as the width Wof the second opening O, it is not possible to obtain the effect of alleviating stress concentration by providing the second memberhaving the second opening O.

(3-1)

The heat exchangerof the above-described embodiments includes the second memberwith the plurality of second openings Oeach having the width Wlarger than the width Wof the first opening Oin the third direction dr. With the second member, stress concentration on the joint portion between the multi-hole heat transfer tubeand the headercan be alleviated, thus improving the pressure resistance strength of the heat exchanger.

The improvement of the pressure resistance strength in the heat exchangerwill be described with reference toto.shows a part of the multi-hole heat transfer tubeand a part of the headercut along a plane passing through the center of the multi-hole heat transfer tubein the third direction drand the center axis of the columnar space Sof the headerin the above-described embodiments.shows the periphery of one multi-hole heat transfer tubein the part of the headershown in.shows a stress-concentrated portion Arindicated by hatching where particularly high stress is generated in a simulation result in a case where a high-pressure refrigerant is caused to flow through the headerand the multi-hole heat transfer tube.

A headershown intohas a configuration in which the second memberas a reinforcing member is removed from the headerof the embodiments.shows the headerdisassembled and viewed obliquely. The first member, the third member, the fourth member, and the fifth membershown inare the same members as the members with the same reference numerals described in the above embodiments. As shown in, in the header, the third memberis brazed to the surface of the first memberextending in the first direction drand the third direction dr.shows a part of the multi-hole heat transfer tubeand a part of the headercut along a plane passing through the center of the multi-hole heat transfer tubein the third direction drand the center axis of the cylindrical space Sof the headerto be compared.shows the periphery of one multi-hole heat transfer tubein the part of the headershown in.shows a stress-concentrated portion Arindicated by hatching where particularly high stress is generated in a simulation result in a case where a high-pressure refrigerant is caused to flow through the headerand the multi-hole heat transfer tube. The simulation results shown inandare results obtained by performing simulations under the same conditions except the shapes of the headers,.

As can be seen from comparison betweenand, when a high-pressure refrigerant is caused to flow, stress-concentrated portions Ar, Arwhere particularly high stress is generated occurring around the first opening Oof the headers,. In the header, a stress-concentrated portion Arwhere particularly high stress is generated also occurring around the joint portion between the multi-hole heat transfer tubeand the header. However, in the header, a stress-concentrated portion Arwhere particularly high stress is generated not occurring around the joint portion between the multi-hole heat transfer tubeand the header. The simulation results shown inandindicate the function of the second memberas a reinforcing member alleviating stress around the joint portion between the multi-hole heat transfer tubeand the header.

(3-2)

In a case where the first memberof the above-described embodiments is an extruded member extruded so as to have an Ω-shaped cross section, the extruded member formed by extrusion can be used as it is for the first memberhaving a complicated shape. With the use of an extruded member for the first memberhaving a complicated shape, it is possible to save time and effort for manufacturing the heat exchangerand to suppress the manufacturing cost to be low.

(3-3)

As shown in, the first memberhas the flat plate portionshaving a flat plate-shape and having a thickness Tlarger than the length Lof the first opening Oin the second direction dr. Since the thickness Tof the flat plate portions of the first memberis larger than the length Lof the first opening Oin the second direction dr, the pressure receiving area that receives pressure from a refrigerant can be made smaller as compared with a case where the thickness Tof the flat plate portionsis the same as the length Lof the first opening Oin the second direction dr. In this way, in the heat exchangerin which the thickness Tof the flat plate portionsis larger than the length Lof the first opening Oin the second direction dr, a pressure resistance strength can be ensured easily.

(3-4)

If the width Wof each second opening Oof the second memberis larger than twice the width Wof the first opening Oof the first member, the first opening Ois less likely to be narrowed by brazing when the first memberand the second memberare brazed.

(3-5)

With the width Wof each second opening Osmaller than half the width Wof each third opening O, it is possible to suppress deterioration of the reinforcing effect of the second member, as compared with a case where the width Wis larger than half the width W.

In the above-described embodiments, in the heat exchanger, the air to be heat-exchanged passes through only one heat exchanging part, as shown in. However, the number of heat exchanging partsthrough which the air to be heat-exchanged passes is not limited to one. For example, two structures shown inmay be arranged double in the third direction drto form one heat exchanger.