JP6550177B1 - Heat exchanger - Google Patents

Abstract

In a heat exchanger, heat exchange performance is further improved. A heat exchanger includes a tube 50 that partitions a first flow path 21 through which exhaust gas (first fluid) flows in a flow path direction and a second flow path 22 through which cooling water (second fluid) flows. And an inner fin 40 disposed in the first flow path 21. The inner fin 40 is cut and raised from the flat wall 41, the standing wall 42 that divides the first flow path 21 into a plurality of small flow paths 23 in a crossing direction of the flat wall 41, and the flat wall 41. Fin portions 43 and 44 projecting into the small flow path 23. The tube 50 has an opposing dimple 77 and vertical dimples 73 and 93 (dimples) that are recessed from the flow path surface 63 facing the first flow path 21 and are raised from the flow path surface 62 facing the second flow path 22. [Selection] Figure 4

Description

  The present invention relates to a heat exchanger in which heat exchange is performed between fluids.

  Patent Document 1 discloses an exhaust heat exchanger that cools the exhaust of an internal combustion engine with cooling water.

  In the exhaust heat exchanger, a tube forming an exhaust flow path is disposed inside the water tank. An inner fin as a heat transfer member for promoting heat exchange between the exhaust and the cooling fluid is disposed in the tube. The exhaust introduced into the exhaust heat exchanger flows in the tube while contacting the inner fins, and is cooled by radiating heat to the cooling water flowing outside the tube.

  The tube is formed with a plurality of dimples as convex portions protruding from the outer surface thereof. The dimples are provided as a means to lower the temperature of the temperature boundary layer of the cooling water.

JP, 2014-169857, A

  However, in recent years, the demand for higher performance of heat exchangers tends to increase, and even in the heat exchanger as described in Patent Document 1, room for improvement is sought for further higher performance. .

  An object of the present invention is to further improve heat exchange performance in a heat exchanger.

According to an aspect of the present invention, there is provided a heat exchanger in which heat exchange is performed between a first fluid and a second fluid, wherein the first flow passage through which the first fluid flows in the flow direction, and a second flow passage A tube separating the second flow passage through which the fluid flows, and an inner fin disposed in the first flow passage, wherein the inner fin crosses the flat wall in contact with the tube and the flat wall It has a standing wall which continues in a direction and divides the first flow path into a plurality of small flow paths arranged in the flow path width direction, and a fin portion which is cut and raised from the flat wall and protrudes into the small flow path. The tube is recessed from a flow passage surface facing the first flow passage and raised from the flow passage surface facing the second flow passage, and a plurality of straddling the small flow passages are opposed to the flow of the second fluid. The opposing dimples extend across the flat wall, and the opposing dimples extend in the flow channel direction. An inclined portion of the pair of oblique, having a cross section in which the inclined portion of the pair cross each other, the heat exchanger is provided, characterized in that.

According to the above embodiment, the heat exchanger, together although the contact area between the tube and the inner fin by depression of opposing dimples is reduced, heat transfer is promoted from the second fluid by opposing dimples into a tube, the the fin portion 1 Heat transfer from the fluid to the tube is facilitated. Thereby, the heat exchanger can enhance the heat exchange performance.

FIG. 1 is a perspective view showing a heat exchanger according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the heat exchanger. FIG. 3 is an exploded perspective view of the tube. FIG. 4 is a perspective view showing a cross section in which a part of the heat exchanger is cut away. FIG. 5 is a perspective view showing a cross section in which a part of the inner fin is cut away. FIG. 6 is a plan view of the inner fin. FIG. 7 is a diagram showing the relationship between the non-contact area ratio A due to dimples and the temperature difference T. As shown in FIG. FIG. 8 is a perspective view showing a cross section of a heat exchanger according to a modification, with a part cut away.

  Hereinafter, a heat exchanger 100 according to an embodiment of the present invention will be described with reference to the attached drawings. In addition, in the attached drawings, a part of the heat exchanger 100 is omitted for simplification of the description.

  The heat exchanger 100 is a water-cooled EGR cooler used in an EGR (Exhaust Gas Recirculation) system (not shown) of a vehicle. The heat exchanger 100 cools a part (first fluid) of the exhaust gas discharged from the engine by the cooling water (second fluid). After flowing through the heat exchanger 100, the cooling water circulating through the cooling circuit circulates through the radiator and radiates heat to the outside air.

  As shown in FIGS. 1 and 2, in the heat exchanger 100, the cooling water is circulated between a plurality of tubes 50 forming the first flow passage 21 through which the exhaust gas flows and the tubes 50 to be stacked. And a casing 10 forming a second flow passage 22.

  Hereinafter, the configuration of the heat exchanger 100 will be described by setting three axes of X, Y, and Z orthogonal to each other in each drawing. In the tube 50, the X axis direction in which the first flow path 21 extends is referred to as "flow path direction", and the Y axis direction is referred to as "flow path width direction".

  As shown in FIG. 2, the tube 50 is formed into a tubular shape that is flat in the Z-axis direction by assembling the semicylindrical upper plate 60 and the lower plate 80. Inner fins 40 are disposed between the upper plate 60 and the lower plate 80 as heat transfer members.

  The upper plate 60 and the lower plate 80 are formed into a flat semi-cylindrical shape by pressing a metal plate.

  The upper plate 60 has a plate-like heat transfer plate portion 61 extending in the X-axis direction and the Y-axis direction. The heat transfer plate portion 61 includes one diagonal dimple 71, one upstream diagonal dimple 72, and four vertical dimples 73 as dimples (protrusions) for guiding the flow of cooling water as described later. A linear dimple) and a large number of opposing dimples 77 (vortex-generated dimples) are formed.

  The lower plate 80 has a plate-like heat transfer plate portion 81 extending in the X-axis direction and the Y-axis direction. In the heat transfer plate portion 81, one diagonal dimple 91, one upstream diagonal dimple 92, and four vertical dimples 93 (linear dimples) are formed as dimples.

  The diagonal dimples 71 and 91, the upstream diagonal dimples 72 and 92, and the vertical dimples 73 and 93 respectively project in the second flow path 22 so as to face each other in the Z-axis direction and guide the flow of cooling water. .

  The casing 10 is formed into a tubular shape having a substantially rectangular cross section by assembling the semicylindrical upper shell 20 and the lower shell 30. Pipes 17 and 18 are connected to the casing 10.

  As shown in FIG. 1, inside the casing 10, a second inlet 25 that distributes the cooling water led from the pipe 17 to the second flow path 22 between the tubes 50, and a cooling that flows out from the second flow path 22. And a second outlet 27 for directing water to the pipe 18.

  An EGR passage pipe (not shown) is connected to both open ends of the casing 10 via frame-shaped headers 15 and 16. Inside the header 15 is provided a first inlet 35 for distributing the exhaust introduced from the pipe of the EGR passage to the first flow passage 21. Inside the header 16 is provided a first outlet 36 for guiding the exhaust flowing out of the first flow passage 21 to the pipe of the EGR passage.

  At the time of manufacturing the heat exchanger 100, an assembly is formed in which the above-described members are assembled. The metal assembly is transferred to the heating furnace and heat treated to join the respective joints by brazing.

  During operation of the heat exchanger 100, the cooling water circulating in the cooling circuit flows from the inside of the pipe 17 into the second inlet 25 and into the second flow path 22 between the tubes 50, as shown by the black arrows in FIG. Distributed. The cooling water flowing through the second flow passage 22 is collected at the second outlet 27 and flows out through the pipe 18. On the other hand, the exhaust gas flowing through the EGR passage is distributed to the first flow passage 21 in each tube 50 through the first inlet 35 in the header 15, as shown by the white arrow in FIG. The exhaust gas flowing through the first flow passage 21 is cooled by radiating heat to the cooling water flowing through the second flow passage 22 through the tubes 50. The exhaust gases flowing out of the first flow passage 21 are collectively supplied through the first outlet 36 in the header 16 to the combustion chamber of the engine.

  Next, the configuration of the tube 50 will be described with reference to FIGS. 3 to 6.

  FIG. 3 is a perspective view showing the upper plate 60 and the inner fins 40 in a state where the tube 50 is disassembled. The inner fins 40 are in the form of a corrugated sheet having a substantially rectangular cross section. In the tube 50, flat walls 41 extending in the X-axis direction and the Y-axis direction and standing walls 42 connected in the cross direction (X-axis direction and the Z-axis direction) of the flat walls 41 are alternately arranged. The offset-type inner fin 40 is offset so that the positions of the flat wall 41 and the upright wall 42 are displaced by a predetermined length in the Y-axis direction for each section divided into the predetermined length in the X-axis direction.

  FIG. 4 is a perspective view showing a cross section in which a part of the tube 50 is cut away. The first flow passage 21 is formed as a flat space between the upper plate 60 and the lower plate 80. The first flow path 21 is divided into a plurality of small flow paths 23 by each segment including the flat wall 41 and the rising wall 42 of the inner fin 40.

  FIG. 5 is a perspective view showing a part of the inner fin 40 in an enlarged manner. The inner fin 40 has an upstream fin portion 43 and a downstream fin portion 44 cut and raised from the flat wall 41 for each segment. The flat wall 41 is provided with fin openings 45 and 46 which are opened at the portions where the fin portions 43 and 44 are cut and raised. The inner fins 40 are formed by press processing.

  The upstream fin portion 43 is cut and raised so as to face upstream with respect to the exhaust flow direction. The fin portion 43 has a trapezoidal shape having a bent side 43a bent from the flat wall 41, an inclined side 43b crossing the small flow passage 23, and a long side 43c and a short side 43d connecting the bent side 43a and the inclined side 43b. It is formed.

  The downstream fin portion 44 is cut and raised so as to face the downstream side in the exhaust flow direction. The fin portion 44 has a trapezoidal shape having a bent side 44a bent from the flat wall 41, an inclined side 44b crossing the small flow path 23, and a long side 44c and a short side 44d connecting the bent side 44a and the inclined side 44b. It is formed.

  The bent side 43a of the upstream fin portion 43 and the bent side 44a of the downstream fin portion 44 are inclined at substantially the same angle with respect to the Y-axis, and are arranged substantially parallel to each other.

  The inclined side 43 b of the upstream fin portion 43 and the inclined side 44 b of the downstream fin portion 44 are disposed to be inclined with respect to the Y axis so as to cross the small flow path 23. As described later, the flow of the exhaust gas flowing through the first flow passage 21 is pivoted around the X axis by being blocked by the inclined sides 43 b and 44 b of the fin portions 43 and 44 extending in the oblique direction with respect to the Y axis. It becomes a spiral longitudinal vortex.

  As shown in FIG. 3, a plurality of opposed dimples 77 are formed in the heat transfer plate portion 61 of the upper plate 60 so as to be aligned along the vertical dimples 73. The distance L between the opposing dimples 77 aligned in the X-axis direction is arbitrarily set according to the performance required of the heat exchanger 100 as described later.

  The V-shaped opposing dimple 77 has a pair of inclined portions 77 a inclined with respect to the Y axis, and a crossing portion 77 b in which the pair of inclined portions 77 a intersect with each other. The opposing dimples 77 are inclined such that the pair of inclined portions 77a open toward the upstream side in the exhaust flow direction, and the intersection portion 77b protrudes toward the downstream side in the exhaust flow direction. As will be described later, the flow of the cooling water flowing through the second flow passage 22 is interrupted by the inclined portions 77a of the opposing dimples 77 extending in the diagonal crossing direction with respect to the Y axis, thereby spiraling around the X axis. Become a vertical vortex of

  As shown in FIG. 4, the facing dimples 77 are formed on the upper plate 60 by pressing. The opposing dimples 77 are raised like a ridge to the flow passage surface 62 facing the second flow passage 22 of the upper plate 60 and are grooved relative to the flow passage surface 63 facing the first flow passage 21 of the upper plate 60. Get depressed. The opposing dimples 77 have groove-like depressions 77c. The vertical dimples 73 are similarly formed on the upper plate 60 by pressing. The vertical dimples 73 have groove-like depressions 73c. Further, vertical dimples 93 are formed on the lower plate 80 by press processing. The vertical dimple 93 has a groove-like depression 93 c.

  FIG. 6 is a plan view showing the inner fin 40 by a solid line and the upper plate 60 by a two-dot chain line. In the upper plate 60, a portion facing the flat wall 41 of the inner fin 40 via the small flow path 23 and a portion to be joined in contact with the flat wall 41 are alternately arranged in the Y-axis direction.

  The V-shaped opposed dimples 77 extend over the flat walls 41 of a plurality of (four) segments across the small flow path 23 in the Y-axis direction.

  The linear vertical dimples 73 extend over the flat walls 41 of the plurality of segments across the small flow path 23 in the X-axis direction.

  As shown in FIG. 4, the fin openings 45 and 46 opened after the fin portions 43 and 44 of the inner fin 40 are cut and raised have a portion facing the recess 93 c of the vertical dimple 93. The fin openings 45 and 46 of the inner fin 40 have portions facing the depressions 77 c of the facing dimples 77 and the depressions 73 c of the vertical dimples 73.

  Next, the operation of the heat exchanger 100 will be described.

  At the time of operation of the heat exchanger 100, the exhaust gas flowing through the EGR passage flows through the first flow passage 21 while being in contact with the inner fins 40 and the tube 50, and the cooling water flowing through the second flow passage 22 through the tube 50 It is cooled by radiating heat. The inner fins 40 function as heat transfer members for transferring the heat of the exhaust to the upper plate 60 and the lower plate 80 of the tube 50.

  The flow of the exhaust gas flowing through the first flow passage 21 is blocked by the fin portions 43 and 44 of the inner fins 40 in the oblique direction with respect to the X axis, thereby generating a spiral longitudinal vortex flowing around the X axis. Thus, in the area including the inner wall surface (flow path surface 63) of the tube 50 and the boundary layer in the vicinity of the surface of the inner fin 40 in the first flow path 21, the heat transfer of the exhaust is promoted by the vortex flow (turbulence). The longitudinal vortices of the exhaust generated downstream of the fin portions 43 and 44 reduce the flow resistance of the exhaust as compared with the lateral vortices turning around the Y axis, and the region causing the turbulent flow becomes larger in the X axis direction .

  On the other hand, the flow of the cooling water flowing through the second flow passage 22 is blocked in the diagonal crossing direction with respect to the X axis by the facing dimples 77, thereby generating a spiral longitudinal vortex flowing around the X axis. Thus, in the area including the boundary layer in the vicinity of the outer wall surface (flow path surface 62) of the tube 50 in the second flow path 22, the heat transfer of the exhaust is promoted by the vortex flow (turbulence).

  The vertical vortex flow of the cooling water generated downstream of the facing dimples 77 suppresses the flow resistance of the cooling water compared to the horizontal vortex flowing around the Y axis, but a range in which a region causing the turbulent flow is in the X axis direction Limited to For this reason, in the heat exchanger 100, the heat transfer of the cooling water is promoted by reducing the distance L between the opposing dimples 77 aligned in the X-axis direction to a certain extent, and the heat exchange efficiency is enhanced.

  However, in the heat exchanger 100, when the distance L between the facing dimples 77 is reduced, the area in which the depressions 77c of the facing dimples 77 face the inner fins 40 increases, so the noncontact area between the tube 50 and the inner fins 40 increases. Do. For this reason, in the heat exchanger 100, when the distance L between the facing dimples 77 is made smaller than a certain degree, the heat transfer amount of the inner fins 40 is reduced, and the heat exchange efficiency is lowered.

FIG. 7 shows that the temperature difference T of the cooling water generated by circulating the heat exchanger 100 during the operation in which the cooling water and the exhaust gas are circulated in the heat exchanger 100 under the predetermined condition is the ratio A of the noncontacting area by the dimples. The value which changes according to is shown the result of having been asked by simulation analysis. The temperature difference T of the cooling water is the difference between the temperature of the cooling water flowing through the second inlet 25 and the temperature of the cooling water flowing through the second outlet 27. The ratio A of the non-contacting area due to the dimples is the case where dimples are provided relative to the contact area B between the tube 50 and the inner fin 40 when the dimples (opposing dimples 77, longitudinal dimples 73 and longitudinal dimples 93) are not provided. The ratio of the contact area C between the tube 50 and the inner fin 40 is expressed by the following equation.
A = (C / B) × 100

  As shown in FIG. 7, the temperature difference T of the cooling water increases gradually as the ratio A of non-contact areas by dimples becomes larger than 0% and takes a peak value, and after taking the peak value, the ratio A becomes larger gradually It gets lower. The temperature difference T becomes equal to or higher than the standard value required in the market when the ratio A is in the range of 2% to 14%.

  In the heat exchanger 100, based on the result of the above simulation analysis, the distance L between the opposing dimples 77 aligned in the X-axis direction is set so that the ratio A of noncontacting areas by dimples falls within the range of 2% to 14%. It is set.

  Next, the effects of the present embodiment will be described.

  [1] According to the present embodiment, in the heat exchanger 100, the first flow path 21 through which the exhaust gas (first fluid) flows in the X axis direction (flow path direction), and the cooling water (second fluid) flow And an inner fin 40 disposed in the first flow path 21. As shown in FIG. The inner fins 40 are continuous in the cross direction of the flat wall 41 in contact with the tube 50 and the flat wall 41, and stand up to divide the first flow passage 21 into a plurality of small flow passages 23 aligned in the Y axis direction (flow passage width direction). It has a wall 42 and fin portions 43 and 44 which are cut and raised from the flat wall 41 and project into the small flow path 23. The tube 50 has a configuration in which the opposing dimples 77 and vertical dimples 73 and 93 (dimples) are depressed from the flow passage surface 63 facing the first flow passage 21 and raised from the flow passage surface 62 facing the second flow passage 22. .

  Based on the above configuration, in the heat exchanger 100, although the inner fins 40 and the tubes 50 transfer heat between the exhaust gas and the cooling water, the facing dimples 77 and the dimples 77c, 73c, 93c of the vertical dimples 73, 93 are provided. The contact area between the tube 50 and the inner fin 40 is reduced. On the other hand, the heat transfer from the cooling water to the tube 50 is promoted by guiding the cooling water by the facing dimples 77 and the vertical dimples 73 and 93. Then, the fin portions 43 and 44 generate a swirl in the flow of the exhaust, thereby promoting heat transfer from the exhaust to the tube 50. As a result, the heat exchanger 100 can be enhanced in heat exchange performance, and can be reduced in size and weight.

  [2] Further, the tube 50 is configured to include, as dimples, opposed dimples 77 extending across the plurality of flat walls 41 across the small flow passage 23 so as to face the flow of the cooling water (second fluid). .

  Based on the above configuration, the cooling water flowing in the second flow path 22 in the X-axis direction becomes an eddy current by passing over the facing dimples 77 disposed to cross the second flow path 22. Thus, in the heat exchanger 100, heat transfer from the cooling water to the tube 50 is promoted by the generation of the vortex flow in the cooling water flow.

  [3] Further, the opposing dimples 77 have a pair of inclined portions 77 a and a pair of inclined portions 77 a that are inclined with respect to the X-axis direction (flow channel direction) so as to oppose the flow of cooling water (second fluid). And a crossing portion 77b crossing each other.

  Based on the above configuration, the cooling water flowing through the second flow passage 22 becomes a longitudinal vortex by passing over the inclined portion 77a and the intersection 77b inclined with respect to the X-axis direction. Thus, in the heat exchanger 100, the generation of the vertical vortex in the cooling water flow by the facing dimples 77 promotes heat transfer from the cooling water to the tube 50 while reducing the flow resistance of the cooling water.

  [4] The tube 50 has vertical dimples 73 and 93 extending in the X-axis direction (flow channel direction) as dimples. The plurality of facing dimples 77 are arranged along the facing dimples 77.

  Based on the above configuration, the cooling water flowing through the second flow path 22 flows in the X axis direction along the vertical dimples 73 and 93. By arranging the plurality of facing dimples 77 along the facing dimples 77, the cooling water circulates in the form of a vortex every time the facing dimples 77 are exceeded. Thus, in the heat exchanger 100, heat transfer from the cooling water to the tube 50 is promoted by the vortices of the cooling water being generated side by side in the X-axis direction.

  [5] The vertical dimples 73 and 93 are configured to be opposed to each other in the Z-axis direction (stacking direction) and to protrude into the second flow path 22.

  Based on the above configuration, the cooling water flowing through the second flow passage 22 flows along the pair of vertical dimples 73 and 93 facing each other, whereby the force flowing in the X-axis direction is enhanced, and the cooling water flows along the vertical dimples 73 and 93. Each time a plurality of opposing dimples 77 are lined up, the vortex becomes a strong vortex. This promotes heat transfer from the cooling water to the tube 50. Moreover, the flow resistance of the cooling water can be suppressed by forming the facing dimples 77 on only one of the pair of tubes 50 stacked on each other.

  [6] The fin openings 45 and 46 opened at the places where the fin portions 43 and 44 of the inner fin 40 are cut and raised are the dimples 77 c and 73 c of the facing dimples 77 and the longitudinal dimples 73 and 93 (dimples) of the tube 50. It was set as the structure which has a part facing 93c.

  [7] The ratio A of the non-contact area where the tube 50 does not contact the inner fin 40 by providing the facing dimples 77 and the vertical dimples 73, 93 (dimples) on the tube 50 is in the range of 2% to 14%. It is set to be set to

  Based on the above configuration, in the heat exchanger 100, the non-contact area between the tube 50 and the inner fin 40 due to the facing dimples 77 and the depressions 77c, 73c, 93c of the longitudinal dimples 73, 93 is suppressed and the facing dimples 77, the longitudinal dimples The effect of promoting heat transfer from the cooling water to the tube 50 by the flow (vortex) of the cooling water led to 73, 93 is sufficiently obtained. Thereby, the heat exchanger 100 can obtain the heat exchange performance required by the market.

  Next, a modification of the tube 50 shown in FIG. 8 will be described.

  In the tube 50 of the above embodiment, the facing dimples 77 are formed on the upper plate 60, and the facing dimples are not formed on the lower plate 80. On the other hand, in the tube 50 according to this modification, the facing dimples 77 are formed on the upper plate 60, and the facing dimples 97 are also formed on the lower plate 80.

  The opposing dimples 77 of the upper plate 60 and the opposing dimples 97 of the lower plate 80 have the same V-shape and are aligned in the Z-axis direction at the same position. The intersection 77 b of the facing dimple 77 and the intersection (not shown) of the facing dimple 97 are aligned at the same position in the Z-axis direction.

  [8] The heat exchanger 100 according to the present modification has a configuration in which the pair of opposing dimples 77 and 97 are opposed to each other in the Z-axis direction (stacking direction) and protrude into the second flow path 22.

  Based on the above configuration, the cooling water flowing through the second flow passage 22 flows over both of the opposing dimples 77 and 97 facing each other, thereby enhancing the force of the vortex flow. This promotes heat transfer from the cooling water to the tube 50.

  As mentioned above, although the embodiment of the present invention was described, the above-mentioned embodiment showed only a part of application example of the present invention, and in the meaning of limiting the technical scope of the present invention to the concrete composition of the above-mentioned embodiment. Absent.

  For example, although the opposing dimples 77 (vortex-generating dimples) in the above-described embodiment are raised in a V-shape, the invention is not limited to this, and may be, for example, a W-shaped rise. The W-shaped opposing dimples 77 have two pairs of slopes and two intersections. In this case, the facing dimples 77 expand the region where the vertical swirl of the cooling water occurs in the Y-axis direction, and the effect of promoting the heat transfer from the cooling water to the tube 50 is enhanced.

  Moreover, although the fin parts 43 and 44 of the said embodiment are cut and raised in the trapezoidal shape which has 4 edge | sides, it may be cut and raised not only in this but the polygonal shape which has 5 or more sides, for example.

  Although this invention is suitable as a heat exchanger mounted in a vehicle, it is applicable also to the heat exchanger used other than a vehicle.

21 first flow path 22 second flow path 23 small flow path 40 inner fin 41 flat wall 42 rising wall 43, 44 fin 45, 46 fin opening 50 tube 62, 63 flow surface 73, 93 vertical dimple (dimple)
73c, 77c, 93c Indentation 77, 97 Opposing dimples (dimples)
77a Inclined part 77b Crossed part 100 heat exchanger

Claims (5)

A heat exchanger in which heat exchange is performed between a first fluid and a second fluid, the heat exchanger comprising:
A tube separating a first flow passage in which the first fluid flows in the flow passage direction and a second flow passage in which the second fluid flows;
And an inner fin disposed in the first flow path,
The inner fin is
A flat wall in contact with the tube,
An upright wall which extends in the cross direction of the flat wall and divides the first channel into a plurality of small channels aligned in the channel width direction;
And a fin portion which is cut and raised from the flat wall and protrudes into the small flow path,
The tube is recessed from a flow passage surface facing the first flow passage, raised from the flow passage surface facing the second flow passage, and a plurality of straddling the small flow passages are opposed to the flow of the second fluid. Opposing dimples extending across the flat wall of
The opposing dimples are
A pair of inclined portions inclined with respect to the flow direction;
The intersections where the inclined portions of the pair intersect each other;
A heat exchanger characterized by The heat exchanger according to claim 1 , wherein
The opposing dimples of the pair project toward the second flow path so as to face each other.
A heat exchanger characterized by A heat exchanger in which heat exchange is performed between a first fluid and a second fluid, the heat exchanger comprising:
A tube separating a first flow passage in which the first fluid flows in the flow passage direction and a second flow passage in which the second fluid flows;
And an inner fin disposed in the first flow path,
The inner fin is
A flat wall in contact with the tube,
An upright wall which extends in the cross direction of the flat wall and divides the first channel into a plurality of small channels aligned in the channel width direction;
And a fin portion which is cut and raised from the flat wall and protrudes into the small flow path,
The tube is
A plurality of the flat walls are depressed from the flow passage surface facing the first flow passage and raised from the flow passage surface facing the second flow passage and straddle the small flow passage so as to face the flow of the second fluid Opposing dimples extending across the
And a vertical dimple extending from the flow passage surface facing the first flow passage and extending from the flow passage surface facing the second flow passage and extending in the flow passage direction.
The plurality of opposing dimples are arranged along the longitudinal dimples,
A heat exchanger characterized by The heat exchanger according to claim 3, wherein
The pair of vertical dimples project into the second flow channel facing each other.
A heat exchanger characterized by A heat exchanger in which heat exchange is performed between a first fluid and a second fluid, the heat exchanger comprising:
A tube separating a first flow passage in which the first fluid flows in the flow passage direction and a second flow passage in which the second fluid flows;
And an inner fin disposed in the first flow path,
The inner fin is
A flat wall in contact with the tube,
An upright wall which extends in the cross direction of the flat wall and divides the first channel into a plurality of small channels aligned in the channel width direction;
And a fin portion which is cut and raised from the flat wall and protrudes into the small flow path,
The tube has a dimple which is recessed from a flow passage surface facing the first flow passage and which protrudes from the flow passage surface facing the second flow passage,
The ratio of the non-contacting area where the tube is not in contact with the inner fin by providing the dimple on the tube is set in the range of 2% to 14%.
A heat exchanger characterized by

Images