JP2009180401A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger with improved strength of plates. <P>SOLUTION: In this heat exchanger with first and second tank portions 26, 28 formed on both end portions inside of a sealed housing 20 by joining a top portion and a trough portion formed on a bent portion 31 to inner peripheral faces of plates 21, 22, a plurality of internal fluid passages 27 are formed to communicate the first and second tank portions 26, 28 with each other, and an inlet portion 24 and an outlet portion 25 are formed on the sealed housing 20. The first fluid flows to the inside of the sealed housing 20 through the inlet portion 24, the first tank portion 26, the internal fluid passage 27, the second tank portion 28 and the outlet portion 25. The second fluid flows through a narrow tube 11, to exchange heat between the first fluid and the second fluid, two sheets of plates 21, 22 are provided with projecting ribs 21c, 22c projecting inward in the top portion direction of a corrugated fin 30. Thus, the strength of the plates can be improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat exchanger that performs heat exchange between a first fluid that flows inside a sealed casing and a second fluid that flows in a thin tube, and in particular, a heat pump that uses a refrigerant as the second fluid. The present invention relates to a heat exchanger applied to a hot water heater.

  Conventionally, what is shown, for example in patent document 1 as this kind of heat exchanger is known. That is, in this heat exchanger, a corrugated plate made of two box-shaped plates having an outer peripheral edge, in which a flat folded surface is continuously formed in a wave shape, is accommodated inside, and the opposing outer peripheral edges An airtight sealed housing that has an inlet portion and an outlet portion that are open to form a first fluid passage from the inlet portion to the outlet portion, and a thin tube wound around the outer periphery of the sealed housing And a heating part that is joined to the outer peripheral surface of the plate to form a second fluid passage.

  In the corrugated plate, opening holes are formed at the left and right alternating side end positions of the wall surfaces connecting the adjacent folded surfaces. The corrugated plate is housed in the sealed casing in a state where the wall surface is orthogonal to the water flow direction of the water passage from the inlet portion to the outlet portion, and the flat folded surface is on the inner peripheral surface of the two plates. It is joined.

In the sealed casing, a wall surface connecting adjacent folded surfaces is partitioned into a number of folded water passages, and a first fluid passage having a long water passage that is alternately folded and meandered at the left and right side ends of the wall surface is formed. Yes. A high-temperature and high-pressure refrigerant is circulated in the heating part that forms the second fluid passage. As a result, the water that has flowed into the sealed casing from the inlet portion flows into the first fluid passage, heat exchange is performed with the refrigerant in the second fluid passage, and the water is heated and discharged from the outlet portion. Is done.
JP 2003-314975 A

  However, in the sealed casing having the configuration as described in Patent Document 1, the water flow path of the first fluid path becomes extremely long by flowing water so as to be substantially in series along the wall surface of the corrugated plate. Therefore, there is a problem that water flow resistance increases.

  Moreover, in the said patent document 1, since the flat return surface of a corrugated board is joined to the internal peripheral surface of two plates, respectively, the intensity | strength (rigidity) of a plate is ensured. However, when a corrugated plate having a rounded surface formed in an R shape is used, there is a problem that the strength of the plate is lowered because the corrugated plate is joined by substantially line contact with the inner peripheral surface of the plate.

  Accordingly, a first object of the present invention is to provide a heat exchanger capable of reducing pressure loss in a fluid passage through which a first fluid flows. The second object of the present invention is to provide a heat exchanger that can increase the strength of the plate.

In order to achieve the above object, the following technical means are adopted. That is, in the first aspect of the present invention, two shallow container-like plates (21, 22) having outer peripheral edges (21a, 22a) are opposed to each other, and the outer peripheral edges (21a, 22a) are joined. A sealed casing (20), a corrugated corrugated fin (30) housed in the sealed casing (20), and a narrow tube (11) wound around the outer peripheral surface of the sealed casing (20) A heat exchanger comprising:
Sealing housing in the direction of the top of the corrugated fin (30) by joining the top and valley formed in the bent portion (31) of the corrugated fin (30) to the inner peripheral surface of the plate (21, 22) The first and second tank portions (26, 28) are formed at both internal ends of (20), and a plurality of internal fluids that communicate with each other with the first and second tank portions (26, 28). A passage (27) is formed, and the sealed casing (20) has an inlet portion (24) communicating with the first tank portion (26) and an outlet portion (25) communicating with the second tank portion (28). Are formed, and the first fluid flows through the inlet portion (24), the first tank portion (26), the plurality of internal fluid passages (27), the second tank portion (28), and the outlet portion (25). And flows through the inside of the sealed casing (20) via the second fluid. By flowing through the capillary (11), a heat exchanger for performing heat exchange between a first fluid and the second fluid,
The two plates (21, 22) are characterized in that convex ribs (21c, 22c) protruding inward are formed in the direction of the top of the corrugated fin (30).

  According to the present invention, since the first fluid flowing in from the inlet portion (24) is circulated in parallel to the plurality of internal fluid passages (27), the pressure of the fluid passage through which the first fluid flows. Loss can be reduced. Moreover, the intensity | strength of a plate (21, 22) can be raised by forming the convex rib (21c, 22c) protruding inside.

  The invention according to claim 2 is characterized in that the convex ribs (21c, 22c) are joined to a part of the wall surface (32) connecting the adjacent bent portions (31). According to the present invention, since the bonding area between the corrugated fin (30) and the two plates (21, 22) increases, the strength of the plates (21, 22) can be increased.

  In the invention described in claim 3, the convex ribs (21c, 22c) are characterized in that the tips of the convex portions are joined. According to the present invention, the strength of the plates (21, 22) can be increased more reliably.

  The invention according to claim 4 is characterized in that the convex ribs (21c, 22c) are formed outside the region where the corrugated fins (30) are arranged. According to the present invention, the strength of the plates (21, 22) can be increased even in a region where the corrugated fins (30) are not disposed. Further, the flow rate of the first fluid that is diverted to the internal fluid passage (27) can be adjusted.

  The invention according to claim 5 is characterized in that one or a plurality of convex ribs (21c, 22c) are formed on each of the two plates (21, 22). According to the present invention, the strength of the plates (21, 22) can be increased.

  The invention according to claim 6 is characterized in that the second fluid flowing through the narrow tube (11) is a refrigerant, and the first fluid is water that exchanges heat with the refrigerant. According to the present invention, in a circulation circuit (not shown) connected to the fluid passage through which the first fluid flows, for example, when the internal pressure in the circulation circuit is increased due to thermal expansion, freezing, or the like of the first fluid, The deformation of the body (20) can be prevented.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment mentioned later.

(First embodiment)
Hereinafter, the heat exchanger in 1st Embodiment is demonstrated based on FIG. 1 thru | or FIG. In the present embodiment, the present invention is applied to a heat exchanger incorporated in a heat pump type water heater using a refrigerant.

  FIG. 1 is a front view showing a schematic configuration of a heat exchanger 1 in the present embodiment. FIG. 2 is a partial cross-sectional view of FIG. 1 viewed from the bottom. FIG. 3 is a front view showing the overall configuration of the sealed casing 20 when the heating unit 10 is removed. 4 is a cross-sectional view taken along line AA shown in FIG.

  As shown in FIG. 1, the heat exchanger 1 of the present embodiment includes a sealed casing 20 having a first fluid passage 23 and a heating unit 10 having a second fluid passage 13. The hermetically sealed casing 20 is a thin rectangular casing in which two thin plates 21 and 22 made of a thin plate (for example, a thickness of about 1 mm) drawn into a shallow container are overlapped to form an airtight structure. It is.

  The sealed casing 20 is composed of two plates 21 and 22 and a corrugated fin 30 accommodated therein. The two plates 21 and 22 are each formed by outer peripheral edges 21a and 22a and outer portions 21b and 22b. The outer portions 21b and 22b protrude outward in a box shape with respect to the outer peripheral edges 21a and 22a, and are formed in a flat surface shape. A container-like sealed housing 20 is formed by joining the outer peripheral edges 21a, 22a to each other by brazing.

  The sealed casing 20 is formed with an inlet 24 and an outlet 25 at both ends. More specifically, the inlet 24 is opened at the outer peripheral edges 21a and 22a at the upper right end shown in FIG. 1, and the outlet 25 is opened at the outer peripheral edges 21a and 22a at the opposite sides (lower left ends). The sealed casing 20 has first and second tank portions 26 and 28 formed at both ends in the vertical direction. The first tank portion 26 communicates with the inlet portion 24, and the second tank portion 28 communicates with the outlet portion 25.

  As shown by an arrow a shown in FIG. 1, the first fluid flows into the sealed casing 20 from the right side toward the first tank portion 26. And the 1st fluid which distribute | circulated the corrugated fin 30 mentioned later flows out outside from the exit part 25 through the 2nd tank part 28, as shown by the arrow b shown in FIG.

  The first tank portion 26 is a tank for diverting the flow of the first fluid flowing in from the inlet portion 24 to a plurality of internal fluid passages 27 described later. The second tank portion 28 is a tank that collects the first fluid that is divided in a plurality of internal fluid passages 27 described later. Further, the first and second tank portions 26 and 28 are formed in the plurality of internal fluid passages 27 so that the flow of the first fluid is made uniform.

  A corrugated fin 30 in which a thin copper plate (for example, a plate thickness of about 0.1 mm) is formed into a corrugated shape is housed in the sealed casing 20. That is, the corrugated fin 30 is disposed between the first tank portion 26 and the second tank portion 28. The corrugated fin 30 has an R-shaped bent portion (top portion, trough portion) 31 continuously formed in a wave shape. The outer shape (vertical × horizontal × height) of the corrugated fin 30 is formed so as to match the inner dimension of the sealed casing 20.

  And it arrange | positions so that the wall surface 32 which connects between the adjacent bending parts 31 may be laminated | stacked on the left-right direction of FIG. 1, and the top part and trough part which are formed in the bending part 31 are inner periphery of the outer parts 21b and 22b. It is joined to the surface by brazing. Thereby, the wall surface 32 which connects between the adjacent bending parts 31 becomes a partition, and the some internal fluid channel | path 27 is formed.

  That is, by disposing the corrugated fins 30 in the sealed casing 20, a plurality of internal fluid passages 27 communicating the first and second tank portions 26 and 28 with each other are formed. A first fluid flows from the first tank portion 26 in parallel to the plurality of internal fluid passages 27.

  In other words, a plurality of internal fluid passages 27 through which the first fluid flows are formed along the top direction of the corrugated fins 30 (the vertical direction in FIG. 1). Accordingly, the first fluid flowing in from the inlet portion 24 flows through the inside of the sealed casing 20 via the first tank portion 26, the plurality of internal fluid passages 27, the second tank portion 28, and the outlet portion 25. .

  Thereby, the 1st fluid channel | path 23 through which the 1st fluid (this example water) from the arrow a shown in FIG. 1 to the arrow b distribute | circulates is formed. And since the wall surface 32 which connects between the adjacent bending parts 31 is functioning as a heat-transfer fin, the 1st fluid which distribute | circulates along this wall surface 32 is heated (it mentions later).

  By the way, the corrugated fin 30 of the present embodiment in which the bent portion 31 is formed in an R shape has the top and valley portions of the bent portion 31 joined to the inner peripheral surfaces of the outer portions 21b and 22b. Since the joint surfaces are in line contact, there is a problem that the strength (rigidity) of the plates 21 and 22 is low when the pressure in the sealed casing 20 rises. In addition, although the bending part 31 was formed in R shape here, the case where the bending part 31 is formed in a substantially trapezoid shape and the width dimension of a top part and a trough part is formed thin is also included.

  Here, for example, in a hot water supply circuit (not shown) through which the first fluid flows, when a malfunction such as a blockage occurs on the downstream side of the heat exchanger 1, the internal pressure in the sealed casing 20 increases. At this time, if the rigidity of the plates 21 and 22 is low, there is a risk of deformation such as the outer portions 21b and 22b bulging outward.

  Therefore, in the present embodiment, in order to eliminate the above-described problems, the outer portions 21b and 22b of the plates 21 and 22 are formed so as to increase the strength. More specifically, as shown in FIG. 2, convex ribs 21c and 22c projecting inward are formed on the respective outer portions 21b and 22b of the plates 21 and 22, respectively.

  The ribs 21c and 22c of the present embodiment are formed such that the projecting portions thereof are in contact with a part of one of the wall surfaces 32. In other words, each of the ribs 21 c and 22 c is formed so as to protrude between the adjacent wall surfaces 32, that is, the valleys of the wall surfaces 32.

  And the protrusion part of the ribs 21c and 22c contact | abutted to a part of wall surface 32 is joined to the top part and trough part of the bending part 31 continuously. Further, as shown in FIG. 3, a plurality of ribs 21c and 22c (three in this example) are formed so as to extend downward from above along the wall surface 32 (in the direction of the top of the corrugated fin 30). Yes.

  In the present embodiment, a plurality of the ribs 21c and 22c are formed on the outer portions 21b and 22b of the plates 21 and 22, respectively. However, at least one rib 21c and 22c is formed at a substantially central portion in the left-right direction of the sealed casing 20. The ribs 21c and 22c may be formed only on the plates 21 and 22, respectively. Thereby, the strength (rigidity) of the two plates 21 and 22 can be increased.

  On the other hand, the heating unit 10 is composed of two copper thin tubes 11 placed in close contact with each other. More specifically, the heating unit 10 is formed by spirally winding two thin tubes 11 around the outer periphery of the sealed casing 20 (see FIGS. 1 and 4).

  The two thin tubes 11 are joined to the outer peripheral surface (front side and back side) of the hermetic casing 20 by filtration. A refrigerant inlet 14 is provided at one end of the two narrow tubes 11, and a refrigerant outlet 15 is provided at the other end. The refrigerant inlet portion 14 is disposed on the lower side of the sealed casing 20, and the refrigerant outlet portion 15 is disposed on the upper side of the sealed casing 20.

  A second fluid passage 13 through which a refrigerant as the second fluid from arrow x to arrow y shown in FIG. 1 flows is formed. The refrigerant inlet 14 is connected to the discharge side of a compressor (not shown). The refrigerant outlet 15 is connected to a liquid receiver (not shown). A high-temperature and high-pressure refrigerant compressed by the compressor is circulated through the second fluid passage 13.

  Next, a method for assembling the heat exchanger 1 having the above configuration will be described. First, the corrugated fins 30 are disposed between the outer portions 21 b and 22 b of the two plates 21 and 22. At this time, the wall surfaces 32 connecting the adjacent bent portions 31 are arranged so as to be laminated in the left-right direction in FIG. And the outer periphery 21a, 22a is contact | abutted and the sealed housing | casing 20 is temporarily assembled.

  Next, the two thin tubes 11 are wound around the outer peripheral surface of the sealed casing 20, and the heating unit 10 is assembled with a predetermined jig. Then, this assembly is put into a heating furnace and joined by brazing. As a result, the corrugated fin 30 is joined to the inner peripheral surfaces of the outer portions 21 b and 22 b of the two plates 21 and 22 and the ribs 21 c and 22 c, and the sealed casing 20 having a sealed structure having the first fluid passage 23. Is formed. Further, the heating unit 10 having the second fluid passage 13 is formed integrally with the sealed casing 20 on the outer periphery of the sealed casing 20. With such a configuration, the heat exchanger 1 of the present embodiment is manufactured by a batch joining by a single brazing process.

  Next, the operation of the heat exchanger 1 having the above configuration will be described. The first fluid (water) that has flowed into the sealed casing 20 from the inlet portion 24 is diverted to the plurality of internal fluid passages 27 via the first tank portion 26. Then, the first fluid (water) that has passed through the plurality of internal fluid passages 27 gathers in the second tank portion 28 and flows out to the outlet portion 25 below. Thereby, since the 1st fluid (water in this example) which flowed in from the inlet_port | entrance part 24 flows substantially parallel along the some wall surface 32, reduction of the pressure loss of the 1st fluid channel | path 23 can be aimed at.

  In the heating unit 10, the high-temperature and high-pressure refrigerant (second fluid) flowing from the lower refrigerant inlet 14 is sequentially guided upward in the pipe 11 and flows out to the upper refrigerant outlet 15. At this time, the first fluid (water) flowing inside the sealed casing 20 is heated through heat exchange with the refrigerant (second fluid) via the outer portions 21b and 22b of the sealed casing 20. The

  Moreover, although the pressure in the airtight housing | casing 20 rises by this heating, since the one or several convex ribs 21c and 22c are formed in each outer part 21b and 22b, it is the plates 21 and 22 The strength (rigidity) can be increased. Furthermore, since the protruding portions of the ribs 21c and 22c are formed so as to be bonded to a part of the wall surface 32, the bonding area of the bonding surface increases, so that the strength of the plates 21 and 22 can be further increased.

(Second Embodiment)
In the first embodiment described above, the protruding portions of the ribs 21c and 22c are formed so as to contact a part of either one of the wall surfaces 32. However, the ribs 21c and 22c are formed between the adjacent wall surfaces 32. You may comprise so that it may provide. FIG. 5 is a partial cross-sectional view showing the formation positions of the ribs 21c and 22c according to the present embodiment.

  As shown in FIG. 5, each of the ribs 21 c and 22 c of the present embodiment is formed so as to protrude between the adjacent wall surfaces 32, that is, between the valleys of the wall surfaces 32. And the rib 21c, 22c is formed in multiple numbers so that it may extend below from upper direction along the wall surface 32 (top part direction of the corrugated fin 30) similarly to 1st Embodiment (refer FIG. 3).

  According to this, the strength (rigidity) of the plates 21 and 22 can be increased by forming the convex ribs 21c and 22c protruding inward on the plates 21 and 22, respectively.

(Third embodiment)
In the present embodiment, the protruding portions of the ribs 21c and 22c are formed so as to face each other. FIG. 6 is a front view showing the overall configuration of the sealed casing 20 in the present embodiment. 7 is a cross-sectional view taken along line BB shown in FIG.

  As shown in FIGS. 6 and 7, the ribs 21 c and 22 c of the present embodiment are formed so that the tips of the protrusions are in contact with each other. And the front-end | tip of the protrusion part of the ribs 21c and 22c is joined. The corrugated fin 30 of this embodiment is divided and accommodated in each of the first fluid passages 23 partitioned by the ribs 21c and 22c.

  More specifically, as shown in FIG. 7, three ribs 21c and 22c are formed in the left-right direction, and each rib 21c and 22c is formed along the wall surface 32 (the top direction of the corrugated fin 30) from above. It is formed so as to extend downward. And the corrugated fin 30 is accommodated between the outer periphery 21a, 22a, rib 21c, 22c, and between rib 21c, 22c.

  Accordingly, the first fluid passage 23 extending from the inlet portion 24 to the outlet portion 25 can be partitioned by the ribs 21c and 22c and the wall surface 32. According to the above configuration, the strength (rigidity) of the plates 21 and 22 can be more reliably increased.

  In the present embodiment, a plurality of ribs 21c and 22c (three in this example) are formed on the outer portions 21b and 22b of the plates 21 and 22, respectively. In addition, at least one rib 21c, 22c may be formed on each of the plates 21, 22.

(Fourth embodiment)
In the above embodiment, the ribs 21c and 22c are formed so as to extend along the wall surface 32. However, the present invention is not limited to this, and the ribs 21c and 22c are formed as shown in FIGS. 8 (a) to 8 (d). You may do it. FIG. 8A to FIG. 8D are front views showing the entire configuration of the sealed casing 20 in the present embodiment.

  In FIG. 8A, the ribs 21c and 22c formed on the outer portions 21b and 22b are formed at a predetermined interval without being formed in a continuous manner. That is, the length of the ribs 21c and 22c is shortened and arranged at the same position. According to this, the strength of the plates 21 and 22 can be increased.

  In FIG. 8B, the ribs 21c and 22c formed on the outer portions 21b and 22b are formed in a zigzag shape. Even in this case, the strength of the plates 21 and 22 can be increased.

  8C, the two ends of the plurality of ribs 21c and 22c are formed outward from the region where the corrugated fins 30 are disposed. That is, one end of each of the ribs 21 c and 22 c is formed so as to protrude into the first tank portion 26. According to this, the flow of the first fluid guided from the first tank portion 26 toward the plurality of internal fluid passages 27 can be adjusted.

  That is, by adjusting the protruding height of the ribs 21c and 22c protruding to the first tank portion 26, the flow of the first fluid guided from the first tank portion 26 toward the plurality of internal fluid passages 27 is made uniform. Can be For example, when the first fluid flows from the right side, a large amount of the first fluid flows through the left internal fluid passage 27 and a small amount of the first fluid easily flows through the right internal fluid passage 27. That is, there is a problem that the uniformity of the diversion is inferior.

  Therefore, as in this embodiment, by forming the ribs 21c and 22c on the side closer to the inlet portion 24 so as to protrude into the first tank portion 26, a resistor is disposed on the inlet side of the first tank portion 26. Therefore, the flow rate guided to the internal fluid passage 27 on the right side can be increased. Therefore, the flow of the first fluid guided from the first tank portion 26 to the plurality of internal fluid passages 27 can be made uniform.

  Further, in FIG. 8D, ribs 21c and 22c are formed as necessary outside the region where the corrugated fins 30 are disposed. Here, the ribs 21 c and 22 c are formed so as to partially protrude from the first and second tank portions 26. And the protrusion height of the ribs 21c and 22c is changed.

  That is, the protruding heights of the ribs 21c and 22c are formed so that the inlet side of the first tank portion 26 and the outlet side of the second tank portion 26 become resistance. According to this, the flow of the 1st fluid guide | induced to the some internal fluid channel | path 27 from the 1st tank part 26 can be equalized more reliably than the said FIG.8 (c).

(Other embodiments)
In the above embodiment, the intervals between the ribs 21c and 22c are arranged to be the same, but the intervals between the ribs 21c and 22c may be appropriately changed in order to make the flow of the first fluid uniform. Moreover, in the above embodiment, although the corrugated fin 30 was formed continuously along the flow direction of the first fluid, it may be divided in a direction perpendicular to the flow direction of the first fluid. . Furthermore, the corrugated fin 30 may be formed with a louver.

  In the above embodiment, the present invention is applied to a heat exchanger incorporated in a heat pump type water heater using a refrigerant. However, the present invention is not limited to this, and is applied to other heat exchangers that perform heat exchange between two types of fluids. Is possible. Further, the fluid flowing through the heating unit 10 is not necessarily limited to the refrigerant.

It is a front view which shows schematic structure of the heat exchanger in 1st Embodiment. It is the fragmentary sectional view which looked at FIG. 1 from the bottom face. It is a front view which shows the whole structure of the sealed housing | casing when the heating part in 1st Embodiment is removed. It is AA sectional drawing shown in FIG. It is a fragmentary sectional view showing the formation position of the rib in a 2nd embodiment. It is a front view which shows the whole structure of the airtight housing | casing in 3rd Embodiment. It is BB sectional drawing shown in FIG. (A) thru | or (d) is a front view which shows the whole structure of the sealed housing | casing in 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Thin tube 13 ... 2nd fluid channel | path 20 ... Sealing housing | casing 21, 22 ... Plate 21a, 22a ... Outer peripheral edge 21c, 22c ... Rib 24 ... Inlet part 25 ... Outlet part 26 ... First tank part 27 ... Internal fluid Passage 28 ... Second tank part 30 ... Corrugated fin 31 ... Bending part 32 ... Wall surface

Claims (6)

A sealed casing (20) in which two shallow container-like plates (21, 22) having outer peripheral edges (21a, 22a) are opposed to each other, and the outer peripheral edges (21a, 22a) are joined;
A corrugated fin (30) having a wave shape housed in the sealed casing (20);
A heat exchanger comprising a thin tube (11) wound around the outer peripheral surface of the sealed casing (20),
By joining the top part and the trough part formed in the bent part (31) of the corrugated fin (30) to the inner peripheral surface of the plate (21, 22), the corrugated fin (30) in the top part direction. First and second tank portions (26, 28) are formed at both ends inside the sealed casing (20), and the first and second tank portions (26, 28) communicate with each other. A plurality of internal fluid passages (27) are formed;
The sealed casing (20) is formed with an inlet part (24) communicating with the first tank part (26) and an outlet part (25) communicating with the second tank part (28), respectively.
The first fluid passes through the inlet part (24), the first tank part (26), the plurality of internal fluid passages (27), the second tank part (28), and the outlet part (25). And flows through the inside of the sealed casing (20) via
In the heat exchanger in which heat exchange is performed between the first fluid and the second fluid by flowing the second fluid through the thin tube (11),
The heat exchanger according to claim 1, wherein convex ribs (21c, 22c) projecting inward are formed on the two plates (21, 22) toward the top of the corrugated fin (30).   The heat exchanger according to claim 1, wherein the convex ribs (21c, 22c) are joined to a part of a wall surface (32) connecting the adjacent bent portions (31). .   The heat exchanger according to claim 1, wherein the convex ribs (21 c, 22 c) are joined at the tips of the convex portions.   The heat exchanger according to claim 1, wherein the convex ribs (21c, 22c) are formed outside a region where the corrugated fins (30) are arranged.   The convex rib (21c, 22c) is formed on each of the two plates (21, 22), or a plurality of the ribs (21c, 22c). The heat exchanger according to item. The second fluid flowing in the narrow tube (11) is a refrigerant,
The heat exchanger according to any one of claims 1 to 5, wherein the first fluid is water that exchanges heat with the refrigerant.

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