JP7801864B2 - heat exchanger - Google Patents

Description

This disclosure relates to a heat exchanger.

Conventionally, heat exchangers such as oil coolers that use offset fins as inner fins are known (see, for example, Patent Document 1). This oil cooler comprises tubes through which oil flows and through which a cooling medium flows on the outside, and offset fins that are disposed within the tubes and perform heat exchange between the oil and the cooling medium. The offset fins have a cross-sectional shape perpendicular to the oil flow direction that is wave-shaped, with convex portions positioned alternately on one side and the other.

JP 2012-17943 A

In heat exchangers using offset fins, a thermal boundary layer forms on the fin wall between the fluids passing on both sides of the offset fins where heat is exchanged between a high-temperature fluid such as oil and a low-temperature fluid such as a cooling medium. The thermal boundary layer is formed by the temperature gradient that occurs between the fluid heated or cooled on the fin wall and the fluid near the wall. The thickness of the thermal boundary layer increases with heat exchange, and when the temperature gradient in the fluid near the wall decreases, heat exchange is suppressed and heat transfer performance decreases, resulting in a decrease in the heat exchange performance of the heat exchanger.

The objective of this disclosure is to provide a heat exchanger that can reduce the thickness of the thermal boundary layer and prevent a decline in heat transfer performance.

The heat exchanger disclosed herein comprises a pair of opposing plates and inner fins disposed between the pair of plates and through which a fluid flows. The inner fins are arranged in a line along the flow direction of the fluid and have a plurality of offset fins disposed offset from one another in a width direction perpendicular to the flow direction. The offset fins include a plate joint portion joined to the plates and having a step portion formed in the flow direction, a fin portion connected to the plate joint portion and disposed along the opposing direction of the pair of plates, and a receiving slope provided at the plate joint portion and oblique to the flow direction, which receives the fluid at the step portion.

Another heat exchanger disclosed herein comprises a pair of opposing plates and inner fins disposed between the pair of plates and through which a fluid flows. The inner fins are arranged in a line along the direction of fluid flow and have a plurality of offset fins that are offset from one another in a width direction perpendicular to the flow direction. The offset fins include plate joints joined to the plates, fin portions connected to the plate joints and disposed along the opposing direction of the pair of plates, and protrusions disposed at the plate joints and protruding inward from the plate joints.

Another heat exchanger disclosed herein comprises a pair of opposing plates and inner fins disposed between the pair of plates and through which a fluid flows. The inner fins are arranged in a row along the direction of fluid flow and have a plurality of offset fins disposed offset from one another in a width direction perpendicular to the flow direction. The offset fins include plate joints joined to the plates, fin portions connected to the plate joints and disposed along the opposing direction of the pair of plates, and holes disposed in the plate joints that extend from the plate joints toward the plates.

This disclosure makes it possible to suppress the formation of a thermal boundary layer and prevent a decrease in heat transfer performance.

FIG. 1 is a perspective view schematically illustrating a heat exchanger according to a first embodiment. FIG. 2 is a perspective view showing offset fins of the heat exchanger according to the first embodiment. FIG. 3 is a two-view diagram of the offset fin. FIG. 4 is a cross-sectional view of an offset fin. FIG. 5 is an explanatory diagram regarding the flow of a fluid. FIG. 6 is a perspective view showing offset fins of a heat exchanger according to the second embodiment. FIG. 7 is a perspective view showing the protrusions of the offset fins. FIG. 8 is a two-view diagram of the offset fin. FIG. 9 is a perspective view showing offset fins of a heat exchanger according to the third embodiment. FIG. 10 is a plan view of the offset fin. FIG. 11 is a cross-sectional view of an offset fin. FIG. 12 is an explanatory diagram regarding the flow of a fluid.

Embodiments of the present disclosure are described in detail below with reference to the drawings. However, the present disclosure is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially identical. Furthermore, the components described below can be combined as appropriate, and if there are multiple embodiments, the respective embodiments can also be combined.

[Embodiment 1]
The heat exchanger 1 according to the first embodiment is a stacked heat exchanger with a pair of plates and inner fins between them, and is a so-called plate-type heat exchanger. In the heat exchanger 1, heat exchange occurs between a high-temperature fluid and a low-temperature fluid flowing inside. The fluid flowing inside the heat exchanger 1 may be a liquid or a gas, and is not particularly limited.

Figure 1 is a schematic perspective view of a heat exchanger according to embodiment 1. Figure 2 is a perspective view showing offset fins of the heat exchanger according to embodiment 1. Figure 3 is a two-sided view of the offset fins. Figure 4 is a cross-sectional view of the offset fins. Figure 5 is an explanatory diagram of the fluid flow.

(heat exchanger)
The heat exchanger 1 includes a plurality of plates 10 and inner fins 12 provided between the plates 10. The plates 10 are formed in a plate shape. The plurality of plates 10 are arranged at predetermined intervals in the direction in which their plate surfaces face each other, i.e., in the thickness direction. A high-temperature fluid flows through one side of the plates 10 in the thickness direction, and a low-temperature fluid flows through the other side of the plates 10 in the thickness direction. The plates 10 are made of a metal material with high heat transfer performance.

The inner fins 12 are provided between a pair of adjacent plates 10 and are joined to the plates 10 by brazing. That is, one side of the inner fin 12 in the thickness direction is joined to one plate 10, and the other side in the thickness direction is joined to the other plate. The inner fins 12 function as a strength member that supports the space between the pair of plates 10. The inner fins 12 also have flow paths through which fluid flows. Therefore, the fluid flows between the pair of opposing plates 10, that is, inside the inner fins 12.

The multiple plates 10 and inner fins 12 are alternately arranged and joined in the thickness direction. Therefore, the flow paths formed by the inner fins 12 are separated by the plates 10, forming multiple lines in the thickness direction. The multiple flow paths lined up in the thickness direction allow the high-temperature fluid and the low-temperature fluid to flow through them, with the flow paths for the high-temperature fluid and the low-temperature fluid alternating. Furthermore, the flow paths are formed so that the fluid flows in one direction in a plane perpendicular to the thickness direction. The flow directions of the high-temperature fluid and the low-temperature fluid are opposite to each other.

When high-temperature fluid and low-temperature fluid are circulated in this heat exchanger 1, the high-temperature fluid flows in a predetermined flow direction, and the low-temperature fluid flows in a flow direction opposite to the flow direction of the high-temperature fluid. The high-temperature fluid and the low-temperature fluid then exchange heat via the plate 10 and inner fins 12.

Next, the inner fin 12 will be described with reference to Figures 2 to 4. As shown in Figures 2 to 4, the inner fin 12 has multiple offset fins 15. The multiple offset fins 15 are arranged in a line along the fluid flow direction. The multiple offset fins 15 are also arranged in a plane perpendicular to the thickness direction, offset from one another in the width direction perpendicular to the fluid flow direction.

The offset fins 15 are provided across the width. The offset fins 15 have peaks 15a that protrude upstream in the flow direction and valleys 15b that recess downstream in the flow direction, forming a wave-like shape with the peaks 15a and valleys 15b alternately arranged along the width direction. The offset fins 15 adjacent to each other in the flow direction are arranged symmetrically with respect to the width direction as the axis of symmetry, and are offset from each other in the width direction. When viewed from a height direction perpendicular to the flow and width directions, the offset fins 15 have an angle θa between the peaks 15a and valleys 15b in a range of 60 to 160 degrees.

As shown in Figure 3, one set of offset fins 15 consists of four rows arranged in the flow direction. The first row of offset fins 15, which is on the upstream side of the flow direction, and the third row of offset fins 15, which is on the downstream side, are located at the same position in the width direction. The second row of offset fins 15 are offset to one side in the width direction (to the right in Figures 3 and 4) relative to the first and third rows of offset fins 15. The fourth row of offset fins 15 are offset to the other side in the width direction (to the left in Figures 3 and 4) relative to the first and third rows of offset fins 15.

Specifically, as shown in Figure 4, the distance between the peaks in the width direction is defined as 1 unit. In this case, the offset fins 15 in the second row are offset by 1/2 unit to one side in the width direction relative to the offset fins 15 in the first and third rows. The offset fins 15 in the fourth row are offset by 1/2 unit to the other side in the width direction relative to the offset fins 15 in the first and third rows. In Embodiment 1, the offset fins 15 in the second and fourth rows are offset by 1/2 unit, but if the shape of the offset fins 15 does not restrict this, it is preferable to offset them in the range of 1/4 unit to 1/2 unit.

Next, we will explain the offset fin 15. The offset fin 15 has a plate joint portion 21, a fin portion 22, and an inhibition portion 23, and these portions are integrated together.

The plate joints 21 are the parts that are joined to the plates 10. The plate joints 21 include a plate joint 21a that is joined to one side of the pair of plates 10, and a plate joint 21b that is joined to the other side of the pair of plates 10. The plate joints 21 are formed in the shape of a parallelogram or a V-shaped plate that is a parallelogram expanded symmetrically in the width direction. The plate joints 21 form part of the peaks 15a and valleys 15b of the offset fins 15. Furthermore, by joining the surface of the plate joints 21 that faces the plate 10 to the plate 10, the end of the plate joints 21 in the flow direction that is exposed on the internal flow channel side is formed as a step 25.

The fin portion 22 is provided across the thickness direction. The fin portion 22 is connected to the widthwise end of the plate joint portion 21. The fin portion 22 is formed in a plate shape.

The inhibiting portion 23 is provided at the plate joint 21. The inhibiting portion 23 is a portion that inhibits the formation of a thermal boundary layer that occurs in the fluid flowing along the inside of the plate joint 21. Specifically, the inhibiting portion 23 is a receiving slope 38 that is oblique to the flow direction and receives the fluid at the step portion 25. Because the receiving slope 38 is oblique to the fluid flow direction, the fluid flowing along the receiving slope 38 becomes a swirling flow that swirls circumferentially around the flow direction as an axis.

Referring to Figure 5, the flow of fluid passing through the inner fin 12 of embodiment 1 will be described. Figure 5 shows a cross section taken along a plane perpendicular to the flow direction, with the upper side of the figure representing the upstream side in the flow direction and the lower side representing the downstream side in the flow direction. As the fluid flows along the receiving slope 38, a flow R1 is generated in the width direction from the peak 15a to the valley 15b as it moves from the upstream side to the downstream side in the flow direction. When the flow R1 from the peak 15a to the valley 15b is applied to the fluid, the fluid becomes a swirling flow R2 that swirls in the flow direction from the peak 15a to the valley 15b. The fluid that becomes the swirling flow R2 has an increased flow velocity on the inner side of the plate joint 21, which inhibits the formation of a thermal boundary layer on the inner side of the plate joint 21.

[Embodiment 2]
Next, a second embodiment will be described with reference to Figs. 6 to 8. In the second embodiment, to avoid redundant description, only parts different from the first embodiment will be described, and parts having the same configuration as the first embodiment will be described using the same reference numerals. Fig. 6 is a perspective view showing offset fins of a heat exchanger according to the second embodiment. Fig. 7 is a perspective view showing protrusions of the offset fins. Fig. 8 is a two-sided view of the offset fins.

(heat exchanger)
In the heat exchanger 50 of the second embodiment, a plurality of offset fins 51 in the inner fin 12 are different from the offset fins 15 of the first embodiment.

The multiple offset fins 51 are arranged in a line along the fluid flow direction. Furthermore, the multiple offset fins 51 are arranged in a plane perpendicular to the thickness direction, with their positions offset from one another in the width direction perpendicular to the fluid flow direction.

The offset fins 51 are provided across the width. In other words, the offset fins 15 are elongated members with the width as their longitudinal direction. As shown in Figures 6 and 8, the offset fins 51 have a plate joint portion 61, a fin portion 62, and an inhibition portion 63, and these portions are integrated.

The plate joint 61 is the portion that is joined to the plate 10. Similar to the plate joint 21 of embodiment 1, the plate joint 61 includes a plate joint 61a that is joined to one side of the pair of plates 10, and a plate joint 61b that is joined to the other side of the pair of plates 10. The plate joint 61 is formed in the shape of a rectangular plate. Furthermore, the surface of the plate joint 61 that faces the plate 10 is joined to the plate 10, so that the end of the plate joint 61 in the flow direction that is exposed on the internal flow path side is formed as a step portion 25.

The fin portion 62 is provided across the thickness direction. The fin portion 62 is connected to the widthwise end of the plate joint portion 61. The fin portion 62 is formed in a plate shape.

The inhibiting portion 63 is provided at the plate joint 61. As in embodiment 1, the inhibiting portion 63 is a portion that inhibits the formation of a thermal boundary layer that occurs in the fluid flowing along the inside of the plate joint 61. Specifically, the inhibiting portion 63 is a protrusion 65 that protrudes inward from the plate joint 61. When the plate joints 61 of adjacent offset fins 51 in the flow direction are continuous, the protrusion 65 is provided at the plate joint 61 on the upstream side in the flow direction.

When viewed from above in the height direction perpendicular to the flow and width directions, the protrusions 65 are formed in a rectangular shape that is long in the flow direction. When viewed from the front in the flow direction, the protrusions 65 are formed in a triangular shape that is convex in the protruding direction. In the second embodiment, the protrusions 65 are rectangular in plan view and triangular in front view, but are not limited to these shapes. When viewed from above, the protrusions 65 may be polygonal, or may be circular, elliptical, or other circular ring-shaped. When viewed from the front, the protrusions 65 may be polygonal, or may be semicircular, elliptical, or other circular arc-shaped.

This protrusion 65 has a first guide slope 65a that slopes from the upstream side to the downstream side in the flow direction and a second guide slope 65b that slopes from one side to the other in the width direction. The first guide slope 65a includes an upstream guide slope 65a and a downstream guide slope 65a. If the angle between the first guide slope 65a and the flow direction is defined as a first slope angle θ1, the first slope angle θ1 ranges from 10 degrees to 60 degrees. Here, the downstream first slope angle θ1 may be the same as the upstream first slope angle θ1 or may be larger than the upstream first slope angle θ1 up to an upper limit of 90 degrees. The second guide slope 65b includes a guide slope 65b on one side in the width direction and a guide slope 65b on the other side in the width direction. If the angle formed by the second guide slope 65b and the width direction is the second inclination angle θ2, the inclination angle θ2 of the second guide slope 65b on both sides in the width direction is the same angle.

As shown in Figure 8, the protrusions 65 are provided at predetermined positions in the flow direction and width direction. Specifically, in the flow direction, the protrusions 65 are positioned at a distance L1 that is equal to or greater than the thickness of the fins 62 from the ends of the plate joints 61. In the width direction, the protrusions 65 are positioned at a distance L2 that is equal to or greater than the thickness of the fins 62 from the fins 62.

In the heat exchanger 50 of embodiment 2, part of the fluid flowing in the flow direction inside the inner fin 12 overcomes the step portion 25 and reaches the protrusion 65, where it flows along the first guide slope 65a. At the plate joint 61, the flow velocity of the fluid flowing along the first guide slope 65a of the protrusion 65 differs from the flow velocity of the fluid flowing along the plate joint 61 without the protrusion 65. This creates a pressure gradient between the fluids, and a cross-sectional secondary flow is generated whose cross section is a plane perpendicular to the flow direction due to the pressure gradient. This cross-sectional secondary flow increases the flow velocity of the fluid inside the plate joint 21, thereby inhibiting the formation of a thermal boundary layer inside the plate joint 21.

In the second embodiment, the protrusions 65 are rectangular in shape with their long sides in the flow direction in plan view, but they may also be arranged as shown by the dotted lines in Figure 8. That is, the protrusions 65 may be rectangular in shape with their long sides inclined relative to the flow direction in plan view. Specifically, if the angle between the length direction of the protrusions 65 and the flow direction is defined as the inclination angle θ3, then the inclination angle θ3 is in the range of 0 to 45 degrees.

[Embodiment 3]
Next, a third embodiment will be described with reference to Figs. 9 to 12. In the third embodiment, to avoid redundant description, only parts different from the first and second embodiments will be described, and parts having the same configuration as the first and second embodiments will be described using the same reference numerals. Fig. 9 is a perspective view showing offset fins of a heat exchanger according to the third embodiment. Fig. 10 is a plan view of the offset fins. Fig. 11 is a cross-sectional view of the offset fins. Fig. 12 is an explanatory diagram of the flow of a fluid.

(heat exchanger)
In the heat exchanger 70 of the third embodiment, a plurality of offset fins 71 in the inner fin 12 are different from the offset fins 15 and 51 of the first and second embodiments.

The multiple offset fins 71 have the inhibitory portion 63 of embodiment 2 replaced with an inhibitory portion 83. Therefore, only the inhibitory portion 83 of the offset fin 71 will be described, and the other portions, the plate joint portion 81 and fin portion 82 of the offset fin 71, will not be described because they are similar to the plate joint portion 61 and fin portion 62 of embodiment 2.

The inhibiting portion 83 is provided at the plate joint 81. As in the first embodiment, the inhibiting portion 83 inhibits the formation of a thermal boundary layer that occurs in the fluid flowing along the inner side of the plate joint 81. Specifically, the inhibiting portion 83 is a hole 85 that extends from the plate joint 81 toward the plate 10. When the plate joints 81 of adjacent offset fins 71 in the flow direction are continuous, the hole 85 is provided at the plate joint 81 downstream in the flow direction. The hole 85 is a through hole that penetrates the plate joint 81. Note that in the third embodiment, the hole 85 is a through hole, but it may also be a hole with a bottom. At least one hole 85 is provided in the inner fin 12 in the flow direction and width direction.

The holes 85 are formed in a rectangular shape when viewed from a height direction perpendicular to the flow direction and width direction. In the third embodiment, the holes 85 are rectangular when viewed from a plane, but this shape is not particularly limited. The holes 85 may be polygonal in a planar view, or may have a circular or elliptical ring shape. The longest length L5 of the holes 85 when viewed from a plane is between two and eight times the thickness of the fin portion 82.

As shown in Figure 10, the holes 85 are arranged at predetermined positions in the flow direction and width direction. Specifically, the holes 85 are arranged in the flow direction at a distance L3 that is equal to or greater than the thickness of the fin portion 82 from the end of the plate joint portion 81. The holes 85 are also arranged in the width direction at a distance L4 that is equal to or greater than the thickness of the fin portion 62 from the fin portion 62.

Next, the plate joint 81 will be described with reference to Figures 11 and 12. The plate joint 81 has a downstream slope 81a formed at its downstream end in the flow direction. The downstream slope 81a is formed downstream of the plate joint 81 in a location where no other plate joints 81 are adjacent to it in the flow direction, i.e., a location where a step 88 is formed (see the conventional example in Figure 12). If the angle between the downstream slope 81a and the flow direction is defined as the downstream inclination angle θ4, then the downstream inclination angle θ4 is in the range of 7 to 45 degrees.

As shown in Figure 12, in the past, when the plate joint 81 did not have a downstream slope 81a, the downstream end of the plate joint 81 became a step 88. As a result, the fluid flowing along the inner surface of the plate joint 81 passed through the step 88, forming a separated region due to the separated flow R3. On the other hand, in embodiment 3, when the plate joint 81 has a downstream slope 81a, the fluid flowing along the inner surface of the plate joint 81 flows along the downstream slope 81a, suppressing the formation of the separated flow R3.

In the heat exchanger 70 of embodiment 3, part of the fluid flowing in the flow direction inside the inner fin 12 passes over the step portion 25 and reaches the hole 85. The fluid flowing along the plate joint 81 separates at the hole 85, thereby initializing the formation of a thermal boundary layer that occurs inside the plate joint 21.

As described above, the heat exchangers 1, 50, and 70 described in this embodiment can be understood, for example, as follows:

The heat exchanger 1 according to the first aspect comprises a pair of opposing plates 10 and inner fins 12 arranged between the pair of plates 10 and through which a fluid flows. The inner fins 12 are arranged in a row along the flow direction of the fluid and have a plurality of offset fins 15 arranged offset from one another in a width direction perpendicular to the flow direction. The offset fins 15 include a plate joint 21 joined to the plate 10 and having a step 25 formed in the flow direction, a fin 22 connected to the plate joint 21 and arranged along the opposing direction of the pair of plates 10, and a receiving slope 38 provided at the plate joint 21 and oblique to the flow direction, which receives the fluid at the step 25.

With this configuration, the receiving slope 38 can impart a swirling flow R2 to the fluid. As a result, the swirling flow R2 increases the flow velocity inside the plate joint 21, effectively inhibiting the formation of a thermal boundary layer inside the plate joint 21. This reduces the thickness of the thermal boundary layer and suppresses a decrease in heat transfer performance through the plate 10, thereby suppressing a decrease in the heat exchange performance of the heat exchanger 1.

In a second aspect, the offset fins 15 have a wave shape in which the upstream portion in the flow direction is a peak 15a and the downstream portion in the flow direction is a valley 15b, and the peaks 15a and valleys 15b are alternately arranged along the width direction. The offset fins 15 on one side adjacent to the flow direction and the offset fins 15 on the other side adjacent to the flow direction are arranged line-symmetrically with respect to the width direction as an axis of symmetry, and are offset from each other in the width direction.

With this configuration, the offset fins 15 can be arranged symmetrically and offset, allowing only one type of offset fin 15 to be used for the inner fin 12, thereby reducing manufacturing costs.

In a third aspect, the offset fins 15 are arranged in four rows in the flow direction to form one set, with the first row of offset fins 15 and the third row of offset fins 15 being at the same position in the width direction, the second row of offset fins 15 being offset to one side in the width direction relative to the first and third rows of offset fins 15, and the fourth row of offset fins 15 being offset to the other side in the width direction relative to the first and third rows of offset fins 15.

This configuration allows the offset fins 15 to be positioned in an optimal manner to prevent the formation of a thermal boundary layer. Furthermore, by arranging a set of offset fins 15 in the flow direction, the inner fins 12 can be easily configured.

The heat exchanger 50 according to the fourth aspect comprises a pair of opposing plates 10 and inner fins 12 arranged between the pair of plates 10 and through which a fluid flows. The inner fins 12 are arranged in a line along the flow direction of the fluid and have a plurality of offset fins 51 arranged offset from one another in a width direction perpendicular to the flow direction. The offset fins 51 include plate joints 61 joined to the plates 10, fin portions 62 connected to the plate joints 61 and arranged along the opposing direction of the pair of plates 10, and protrusions 65 provided on the plate joints 61 and protruding inward from the plate joints 61.

With this configuration, the protrusions 65 can impart a cross-sectional secondary flow to the fluid. This cross-sectional secondary flow increases the flow velocity inside the plate joint 21, effectively inhibiting the formation of a thermal boundary layer inside the plate joint 21. This reduces the thickness of the thermal boundary layer and suppresses a decrease in heat transfer performance through the plate 10, thereby suppressing a decrease in the heat exchange performance of the heat exchanger 50.

In a fifth aspect, when the plate joints 61 of adjacent offset fins 51 in the flow direction are continuous, the protrusions 65 are provided on the plate joints 61 on the upstream side in the flow direction.

With this configuration, the protrusions 65 can impart a cross-sectional secondary flow on the upstream side of the flow direction, effectively inhibiting the formation of a thermal boundary layer on the downstream side.

In a sixth aspect, the protrusion 65 has at least one of a guide slope 65a that slopes from the upstream side to the downstream side in the flow direction and a guide slope 65b that slopes from one side to the other in the width direction.

With this configuration, the fluid can be easily imparted with a cross-sectional secondary flow by circulating the fluid along the guide slopes 65a and 65b.

In a seventh aspect, the protrusion 65 has an elongated shape that is inclined relative to the flow direction.

With this configuration, the fluid can be easily imparted with a cross-sectional secondary flow by circulating the fluid along the length of the protrusion 65.

In an eighth aspect, the protrusion 65 is arranged in the flow direction at a distance L1 that is equal to or greater than the thickness of the fin portion 62 from the end of the plate joint portion 61, and in the width direction at a distance L2 that is equal to or greater than the thickness of the fin portion 62 from the fin portion 62.

This configuration allows the protrusions 65 to be positioned in a way that is suitable for imparting cross-sectional secondary flow to the fluid.

The heat exchanger 70 according to the ninth aspect comprises a pair of opposing plates 10 and inner fins 12 arranged between the pair of plates 10 and through which a fluid flows. The inner fins 12 are arranged in a line along the flow direction of the fluid and have a plurality of offset fins 71 arranged offset from one another in a width direction perpendicular to the flow direction. The offset fins 71 include plate joints 81 joined to the plates 10, fin sections 82 connected to the plate joints 81 and arranged along the opposing direction of the pair of plates 10, and holes 85 formed in the plate joints 81 and extending from the plate joints 81 toward the plates 10.

With this configuration, the holes 85 allow the fluid flow to separate. Therefore, by separating the fluid flow, the formation of a thermal boundary layer can be initialized, effectively inhibiting its formation. This reduces the thickness of the thermal boundary layer, suppressing a decrease in heat transfer performance via the plate 10, thereby suppressing a decrease in the heat exchange performance of the heat exchanger 70.

In a tenth aspect, when the plate joints 81 of the offset fins 71 adjacent in the flow direction are continuous, the holes 85 are provided in the plate joints 81 downstream in the flow direction.

With this configuration, the formation of the thermal boundary layer can be initialized downstream where the thermal boundary layer thickens due to the holes 85, thereby effectively inhibiting the formation of the thermal boundary layer downstream.

In an eleventh aspect, the longest length of the hole 85 within the plane of the plate 10 is between two and eight times the thickness of the fin portion 82.

This configuration allows the size of the holes 85 to be set to a size suitable for initializing the formation of a thermal boundary layer.

In a twelfth aspect, the holes 85 are arranged in the flow direction at a distance L3 that is equal to or greater than the thickness of the fin portion 82 from the end of the plate joint portion 81, and in the width direction at a distance L4 that is equal to or greater than the thickness of the fin portion 82 from the fin portion 82.

This configuration allows the holes 85 to be positioned in a way that is suitable for initializing the formation of a thermal boundary layer.

In a thirteenth aspect, the plate joint 81 is formed at the end on the downstream side in the flow direction and has a downstream slope 81a that slopes toward the plate 10 as it moves downstream in the flow direction.

With this configuration, the fluid flows along the downstream slope 81a, suppressing the formation of separated flow R3. Therefore, by suppressing the formation of separated flow R3, the heat transfer area of the fluid downstream of the plate joint 81 can be increased, improving heat transfer performance. Furthermore, suppressing the formation of separated flow R3 can reduce pressure loss.

REFERENCE SIGNS LIST 1 heat exchanger 10 plate 12 inner fin 15 offset fin 21 plate joint 22 fin portion 23 obstruction portion 25 step portion 38 receiving slope 50 heat exchanger (embodiment 2)
51 offset fin 61 plate joint portion 62 fin portion 63 obstruction portion 65 protrusion portion 70 heat exchanger (third embodiment)
71 offset fin 81 plate joint portion 82 fin portion 83 obstruction portion 85 hole 88 step portion

Claims (11)

A pair of opposing plates;
an inner fin provided between the pair of plates and through which a fluid flows;
The inner fin is
a plurality of offset fins that are arranged side by side along the flow direction of the fluid and are offset from one another in a width direction perpendicular to the flow direction;
The offset fins are
a plate joint portion joined to the plate and having a step portion formed in the flow direction;
a fin portion connected to the plate joint portion and provided along the opposing direction of the pair of plates;
a receiving inclined surface provided at the plate joint portion, inclined with respect to the flow direction, for receiving the fluid at the step portion. The offset fin has a wave shape in which a portion on the upstream side in the flow direction is a peak portion and a portion on the downstream side in the flow direction is a valley portion, and the peaks and the valleys are alternately provided along the width direction,
2. The heat exchanger according to claim 1, wherein the offset fins on one side adjacent to the flow direction and the offset fins on the other side adjacent to the flow direction are arranged symmetrically with respect to the width direction as an axis of symmetry, and are arranged with their positions offset from each other in the width direction. The offset fins are arranged in four rows in the flow direction as one set,
the offset fins in the first row and the offset fins in the third row are at the same position in the width direction,
The offset fins in the second row are offset to one side in the width direction relative to the offset fins in the first and third rows,
3. The heat exchanger according to claim 1, wherein the offset fins in the fourth row are offset to the other side in the width direction relative to the offset fins in the first and third rows. A pair of opposing plates;
an inner fin provided between the pair of plates and through which a fluid flows;
The inner fin is
a plurality of offset fins that are arranged side by side along the flow direction of the fluid and are offset from one another in a width direction perpendicular to the flow direction;
The offset fins are
a plate joint portion joined to the plate;
a fin portion connected to the plate joint portion and provided along the opposing direction of the pair of plates;
a protrusion provided at the plate joint portion and protruding inward from the plate joint portion ,
When the plate joint portions are continuous in the offset fins adjacent in the flow direction,
a heat exchanger in which the protrusion is provided at the plate joint on the upstream side in the flow direction, but is not provided at the plate joint on the downstream side in the flow direction ; 5. The heat exchanger according to claim 4, wherein the protrusion has at least one of a guide slope that slopes from the upstream side to the downstream side in the flow direction and a guide slope that slopes from one side to the other side in the width direction. The heat exchanger according to claim 4 , wherein the protrusions are elongated in a direction inclined with respect to the flow direction. The protrusion is
In the flow direction, the fin portion is disposed at a distance equal to or greater than the thickness of the fin portion from an end of the plate joint portion,
The heat exchanger according to claim 4 , wherein the first and second fin portions are spaced apart from each other in the width direction by a distance equal to or greater than the thickness of the fin portion. A pair of opposing plates;
an inner fin provided between the pair of plates and through which a fluid flows;
The inner fin is
a plurality of offset fins that are arranged side by side along the flow direction of the fluid and are offset from one another in a width direction perpendicular to the flow direction;
The offset fins are
a plate joint portion joined to the plate;
a fin portion connected to the plate joint portion and provided along the opposing direction of the pair of plates;
a hole provided at the plate joint portion and extending from the plate joint portion toward the plate ,
When the plate joint portions are continuous in the offset fins adjacent in the flow direction,
A heat exchanger in which the holes are provided at the plate joints on the downstream side in the flow direction, but not at the plate joints on the upstream side in the flow direction . 9. The heat exchanger according to claim 8 , wherein the longest length of the holes within the surface of the plate is between two and eight times the thickness of the fin portion. The hole is
In the flow direction, the fin portion is disposed at a distance equal to or greater than the thickness of the fin portion from an end of the plate joint portion,
The heat exchanger according to claim 8 or 9 , wherein the first and second fin portions are spaced apart from each other in the width direction by a distance equal to or greater than the thickness of the fin portion. 11. The heat exchanger according to claim 1, wherein the plate joint portion is formed at a downstream end portion in the flow direction and has a downstream slope that slopes toward the plate toward the downstream side in the flow direction.