Heat transfer plate and heat exchange element

In a first and second corrugated portions of a first and second heat transfer plates, first front-side convex portions that are convex toward one side in a first direction and first back-side convex portions that are convex toward the opposite side in the first direction are alternately formed along a second direction. In at least one end of both ends of each of the first front-side convex portions in the second direction, a first front-side protruding portion protruding toward another first front-side convex portion is provided. The first front-side protruding portion is contactable with the second heat transfer plate. In at least one end of both ends of each of the second front-side convex portions in the second direction, a second front-side protruding portion protruding toward another second front-side convex portion is provided. The second front-side protruding portion is contactable with the first heat transfer plate.

FIELD

The present disclosure relates to a heat transfer plate that performs heat exchange between air flows, and a heat exchange element including the heat transfer plate.

BACKGROUND

Conventionally, a heat exchange element that performs heat exchange between a supply air flow that flows from the outside to the inside of a room and an exhaust air flow that flows from the inside to the outside of the room is known. Ventilation using such a heat exchange element can secure good air quality in the room while improving the efficiency of cooling and heating in the room and reducing energy used for air conditioning in the room.

Patent Literature 1 discloses a heat exchange element formed by stacked sheet-like heat transfer plates. A plurality of flow paths are formed between adjacent ones of the heat transfer plates. Each of the plurality of heat transfer plates has a corrugated portion formed in a corrugated shape. Parts of the plurality of flow paths are formed by the corrugated portions. In each of the corrugated portions, convex portions that are convex toward one side in the stacking direction and convex portions that are convex toward the opposite side in the stacking direction are alternately formed along the flow path width direction.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Translation of PCT International Application Laid-open No. 2015-509178

SUMMARY

Technical Problem

However, according to the technique disclosed in Patent Literature 1, sheet-like heat transfer plates are used, so that the rigidity of the corrugated portions cannot be secured, and there is a possibility that the corrugated portions are deformed to fall when the plurality of heat transfer plates are stacked. As a result, the flow paths may be blocked or excessively opened, causing variations in pressure loss among the plurality of flow paths and then causing deterioration of the heat exchange efficiency, which is disadvantageous.

The present disclosure has been made in view of the above, and an object thereof is to obtain a heat transfer plate capable of suppressing deformation of corrugated portions.

Solution to Problem

In order to overcome the above-described disadvantage and achieve the object, a heat transfer plate according to the present disclosure includes a plurality of flow paths formed on both front and back surfaces in a first direction and is for forming a heat exchange element by stacking a plurality of the heat transfer plates in the first direction, the heat transfer plate including a corrugated portion having a corrugated shape that forms parts of respective ones of the plurality of flow paths. The corrugated portion includes front-side convex portions that are convex toward one side in the first direction aback-side convex portions that are convex toward an opposite side in the first direction, the front-side convex portions and the back-side convex portions being formed alternately along a second direction orthogonal to the first direction. At at least one of both ends of each of the front-side convex portions in the second direction, there is provided a front-side protruding portion that protrudes toward another one, adjacent in the second direction, of the front-side convex portions and that is contactable with another one, adjacent to the heat transfer plate in the first direction, of the heat transfer plates included in the heat exchange element.

Advantageous Effects of Invention

The heat transfer plate according to the present disclosure has an effect of suppressing deformation of the corrugated portion.

DESCRIPTION OF EMBODIMENTS

Hereinafter, heat transfer plates and heat exchange elements according to embodiments of the present disclosure will be described in detail with reference to the drawings.

First Embodiment

FIG.1is a perspective view illustrating a heat exchange element100according to a first embodiment. An arrow Y inFIG.1indicates a flow of fluid. The heat exchange element100is formed to have a hexagonal columnar shape. The heat exchange element100is formed by first heat transfer plates1and second heat transfer plates2stacked alternately. The first heat transfer plates1and the second heat transfer plates2are formed using resin sheets having polypropylene, polystyrene, polyethylene terephthalate, or the like as a base material. Between the front surface of one of the first heat transfer plates1and the back surface of the adjacent one of the second heat transfer plates2, a plurality of first flow paths3are formed. Between the back surface of one of the first heat transfer plates1and the front surface of the adjacent one of the second heat transfer plates2, a plurality of second flow paths4are formed. The first flow paths3and the second flow paths4are flow paths independent of each other. In the following description, fluid flowing through the first flow paths3is referred to as a “first air flow5”, and fluid flowing through the second flow paths4is referred to as a “second air flow6”. A direction in which the first heat transfer plates1and the second heat transfer plates2are stacked is referred to as a “stacking direction”. The length direction of each of the flow paths3and4is referred to as a “flow path length direction”. The width direction of each of the flow paths3and4is referred to as a “flow path width direction”. The stacking direction, the flow path length direction, and the flow path width direction are orthogonal to each other. The word “orthogonal” in the present specification may express a relationship that is not strictly orthogonal and slightly oblique in addition to a relationship that is completely orthogonal. In addition, the first heat transfer plates1and the second heat transfer plates2may be collectively referred to as heat transfer plates1and2.

FIG.2is a plan view illustrating one of the first heat transfer plates1of the heat exchange element100according to the first embodiment. The first heat transfer plate1includes: a first corrugated portion11; a first header portion12connected to one end of the first corrugated portion11along the flow path length direction; and a second header portion13connected to the opposite end of the first corrugated portion11along the flow path length direction. Solid arrows inFIG.2indicate the flow of the first air flow5over: the front surface of the first corrugated portion11; the front surface of the first header portion12; and the front surface of the second header portion13. Broken-line arrows illustrated inFIG.2indicate the flow of the second air flow6over: the back surface of the first corrugated portion11; the back surface of the first header portion12; and the back surface of the second header portion13.

The first corrugated portion11is a portion: that forms a plurality of first partial flow paths31between the first corrugated portion11and the back surface of one of second corrugated portions21described below; and that forms a plurality of fourth partial flow paths41between the first corrugated portion11and the front surface of one of the second corrugated portions21. The shape of the first corrugated portion11when viewed from the stacking direction is a rectangle. The plurality of first partial flow paths31are parts of respective ones of the plurality of first flow paths3. The plurality of fourth partial flow paths41are parts of respective ones of the plurality of second flow paths4. The first corrugated portion11is formed in a corrugated shape formed by peaks and valleys that are alternately continued. The first corrugated portion11will be described in detail later.

The first header portion12is a portion that forms a plurality of second partial flow paths32between the first header portion12and the back surface of a third header portion22to be described below. The shape of the first header portion12when viewed from the stacking direction is an isosceles triangle. The plurality of second partial flow paths32are connected to ends of respective ones of the first partial flow paths31, and is parts of respective ones of the plurality of first flow paths3. On the front surface of the first header portion12, a plurality of first flow path ribs12aare formed at intervals. The first flow path ribs12aabut on the back surface of the third header portion22described below. Between the front surface of the first header portion12and the back surface of the third header portion22, the plurality of second partial flow paths32defined by the first flow path ribs12aare formed. The lengths of the plurality of second partial flow paths32are different from each other. The lengths of the second partial flow paths32are shorter from one side to the opposite side in the flow path width direction.

The second header portion13is a portion that forms a plurality of third partial flow paths33between the second header portion13and the back surface of a fourth header portion23to be described below. The shape of the second header portion13when viewed from the stacking direction is an isosceles triangle. The plurality of third partial flow paths33are connected to the opposite ends of respective ones of the first partial flow paths31, and are parts of respective ones of the plurality of first flow paths3. On the front surface of the second header portion13, a plurality of second flow path ribs13aare formed at intervals. The second flow path ribs13aabut on the back surface of the fourth header portion23described below. Between the front surface of the second header portion13and the back surface of the fourth header portion23, the plurality of third partial flow paths33defined by the second flow path ribs13aare formed. The lengths of the plurality of third partial flow paths33are different from each other. The lengths of the third partial flow paths33are longer from one side to the opposite side in the flow path width direction. The first flow path ribs12aand the second flow path ribs13aare inclined with respect to the flow path length direction of the first partial flow paths31. That is, the second partial flow paths32and the third partial flow paths33are inclined with respect to first partial flow paths31. The first air flow5flowing in from the third partial flow paths33passes through the second partial flow paths32via the first partial flow paths31.

FIG.3is a plan view illustrating one of the second heat transfer plates2of the heat exchange element100according to the first embodiment. The second heat transfer plate2includes: a second corrugated portion21; a third header portion22connected to one end of the second corrugated portion21along the flow path length direction; and a fourth header portion23connected to the opposite end of the second corrugated portion21along the flow path length direction. Solid arrows inFIG.3indicate the flow of the second air flow6flowing over the front surface of the second corrugated portion21, the front surface of the third header portion22, and the front surface of the fourth header portion23. Broken-line arrows illustrated inFIG.3indicate the flow of the first air flow5flowing over the back surface of the second corrugated portion21, the back surface of the third header portion22, and the back surface of the fourth header portion23.

The second corrugated portion21is a portion: that forms the plurality of fourth partial flow paths41between the second corrugated portion21and the back surface of the first corrugated portion11; and that forms the plurality of first partial flow paths31between the second corrugated portion21and the front surface of the first corrugated portion11. The shape of the second corrugated portion21when viewed from the stacking direction is a rectangle. The plurality of fourth partial flow paths41are parts of respective ones of the plurality of second flow paths4. The plurality of first partial flow paths31are parts of respective ones of the plurality of first flow paths3. The second corrugated portion21is formed in a corrugated shape formed by peaks and valleys that are alternately continued. The second corrugated portion21will be described in detail later. As illustrated inFIGS.2and3, the first partial flow paths31and the fourth partial flow paths41are parallel to each other. The flow direction of the first air flow5passing through the first partial flow paths31and the flow direction of the second air flow6passing through the fourth partial flow paths41are different from each other by 180 degrees. Heat is transferred between the first air flow5passing through the first partial flow paths31and the second air flow6passing through the fourth partial flow paths41. The heat exchange element100may be configured to transfer sensible heat and latent heat between air flows, or may be configured to transfer only sensible heat.

As illustrated inFIG.3, the third header portion22is a portion that forms a plurality of fifth partial flow paths42between the third header portion22and the back surface of the first header portion12. The shape of the third header portion22when viewed from the stacking direction is an isosceles triangle. The plurality of fifth partial flow paths42are connected to one ends of respective ones of the fourth partial flow paths41, and are parts of respective ones of the plurality of second flow paths4. On the front surface of the third header portion22, a plurality of third flow path ribs22aare formed at intervals. The third flow path ribs22aabut on the back surface of the first header portion12. Between the front surface of the third header portion22and the back surface of the first header portion12, the plurality of fifth partial flow paths42defined by the third flow path ribs22aare formed. The lengths of the plurality of fifth partial flow paths42are different from each other. The lengths of the fifth partial flow paths42are longer from one side to the opposite side in the flow path width direction. As illustrated inFIGS.2and3, the flow direction of the first air flow5passing through the second partial flow paths32and the flow direction of the second air flow6passing through the fifth partial flow paths42intersect each other.

As illustrated inFIG.3, the fourth header portion23is a portion that forms a plurality of sixth partial flow paths43between the fourth header portion23and the back surface of the second header portion13. The shape of the fourth header portion23when viewed from the stacking direction is an isosceles triangle. The plurality of sixth partial flow paths43are connected to the opposite ends of respective ones of the fourth partial flow paths41, and is parts of respective ones of the plurality of second flow paths4. On the front surface of the fourth header portion23, a plurality of fourth flow path ribs23aare formed at intervals. The fourth flow path ribs23aabut on the back surface of the second header portion13. Between the front surface of the fourth header portion23and the back surface of the second header portion13, the plurality of sixth partial flow paths43defined by the fourth flow path ribs23ais formed. The lengths of the plurality of sixth partial flow paths43are different from each other. The lengths of the sixth partial flow paths43are shorter from one side to the opposite side in the flow path width direction. The third flow path ribs22aand the fourth flow path ribs23aare inclined with respect to the flow path length direction of the fourth partial flow paths41. That is, the fifth partial flow paths42and the sixth partial flow paths43are inclined with respect to the fourth partial flow paths41. The second air flow6flowing in from the fifth partial flow paths42passes through the sixth partial flow paths43via the fourth partial flow paths41. As illustrated inFIGS.2and3, the flow direction of the first air flow5passing through the third partial flow paths33and the flow direction of the second air flow6passing through the sixth partial flow paths43intersect each other.

The first corrugated portion11will be described in detail with reference toFIG.4.FIG.4is a cross-sectional view taken along line IV-IV inFIGS.2and3. In the first corrugated portion11, first front-side convex portions14that are convex toward one side in the stacking direction and first back-side convex portions15that are convex toward the opposite side in the stacking direction are alternately formed along the flow path width direction. Two-dot chain lines Ca inFIG.4are center lines passing through the centers of the first corrugated portions11in the stacking direction, and are boundary lines between the first front-side convex portions14and the first back-side convex portions15. Hereinafter, an upward direction that is one side in the stacking direction is defined as +X, and a downward direction that is the opposite side in the stacking direction is defined as −X.

At both ends of each of the first front-side convex portions14in the flow path width direction, there are provided first front-side protruding portions16. The first front-side protruding portions16protrude toward the other first front-side convex portions14, adjacent in the flow path width direction. The first front-side protruding portions16are contactable with the second heat transfer plates2that are adjacent to the first heat transfer plate1in the +X direction in the stacking direction. The first front-side protruding portions16serve to support second back-side convex portions25, to be described below, of the second heat transfer plate2. The first front-side protruding portions16are preferably provided within a range from the middle between apex portions14aof the first front-side convex portions14and apex portions15aof the first back-side convex portions15to the apex portions14aof the first front-side convex portions14in the stacking direction. The first front-side protruding portions16are more preferably provided at a position close to the apex portions14aof the first front-side convex portions14in the stacking direction. The first front-side protruding portions16do not protrude in the +X direction of the stacking direction from the apex portions14aof the first front-side convex portions14. The first front-side protruding portions16are formed to have a symmetrical shape in the stacking direction. The shape of the first front-side protruding portions16is not particularly limited. However, in the first embodiment, the first front-side protruding portions16are hollow semicircular shape that is convex toward the other first front-side convex portions14adjacent in the flow path width direction. The plate thickness of the first front-side convex portions14including the first front-side protruding portions16is uniform.

The first corrugated portion11includes a plurality of first front-side flow paths11aand a plurality of first back-side flow paths11b. The first front-side flow paths11aand the first back-side flow paths11bare alternately arranged in the flow path width direction. The first front-side flow paths11aserve as the first partial flow paths31through which the first air flow5passes. The first back-side flow paths11bserve as the fourth partial flow paths41through which the second air flow6passes. The first front-side flow paths11aare quadrangular flow paths each formed by two of the first front-side convex portions14adjacent to one of the first back-side convex portions15in the flow path width direction and a corresponding one of the second back-side convex portions25to be described below that surround the quadrangular flow path. The first back-side flow paths11bare quadrangular flow paths each formed by two of the first back-side convex portions15adjacent to one of the first front-side convex portions14in the flow path width direction, and a corresponding one of second front-side convex portions24to be described below that surround the quadrangular flow path. In the first front-side flow paths11a, the first front-side protruding portions16are disposed. When the interval between the centers of two adjacent ones of the first front-side flow paths11ais defined as one pitch, the number of pitches of the first front-side flow paths11ais preferably 40 or more, more preferably 80 or more, still more preferably 140 or more. When the interval between the centers of two adjacent ones of the first back-side flow paths11bis defined as one pitch, the number of pitches of the first back-side flow paths11bis preferably 40 or more, more preferably 80 or more, still more preferably 140 or more.

The second corrugated portion21will be described in detail with reference toFIG.4. In the second corrugated portion21, the second front-side convex portions24that are convex toward one side in the stacking direction and the second back-side convex portions25that are convex toward the opposite side in the stacking direction are alternately formed along the flow path width direction. Two-dot chain line Cb inFIG.4are center lines passing through the centers of the second corrugated portions21in the stacking direction, and are boundary lines between the second front-side convex portions24and the second back-side convex portions25. The first front-side convex portions14and the second front-side convex portions24are disposed at positions coinciding with each other in the stacking direction. The first back-side convex portions15and the second back-side convex portions25are disposed at positions coinciding with each other in the stacking direction.

At both ends of each of the second front-side convex portions24in the flow path width direction, there are provided second front-side protruding portions26. The second front-side protruding portions26protrude toward the other second front-side convex portions24, adjacent in the flow path width direction. The second front-side protruding portions26are contactable with the first heat transfer plates1adjacent to the second heat transfer plate2in the +X direction in the stacking direction. The second front-side protruding portions26serve to support the first back-side convex portions15of the first heat transfer plate1. The second front-side protruding portions26are preferably provided within a range from the middle between apex portions24aof the second front-side convex portions24and apex portions25aof the second back-side convex portions25to the apex portions24aof the second front-side convex portions24in the stacking direction. The second front-side protruding portions26are more preferably provided at a position close to the apex portions24aof the second front-side convex portions24in the stacking direction. The second front-side protruding portions26do not protrude from the apex portions24aof the second front-side convex portions24in the +X direction of the stacking direction. The second front-side protruding portions26are formed to have a symmetrical shape in the stacking direction. The shape of the second front-side protruding portions26is not particularly limited. However, in the first embodiment, the second front-side protruding portions26are hollow semicircular shape that is convex toward the other second front-side convex portions24adjacent in the flow path width direction. The plate thickness of the second front-side convex portions24including the second front-side protruding portions26is uniform.

The second corrugated portion21includes: a plurality of second front-side flow paths21a; and a plurality of second back-side flow paths21b. The second front-side flow paths21aand the second back-side flow paths21bare alternately arranged in the flow path width direction. The second front-side flow paths21aserve as the fourth partial flow paths41through which the second air flow6passes. The second back-side flow paths21bserve as the first partial flow paths31through which the first air flow5passes. The second front-side flow paths21aare quadrangular flow paths each surrounded and formed by: the second back-side convex portions25; two of the second front-side convex portions24adjacent to each other in the flow path width direction; and a corresponding one of the first back-side convex portions15. The second back-side flow paths21bare quadrangular flow paths each surrounded and formed by: the second front-side convex portions24; two of the second back-side convex portions25adjacent to each other in the flow path width direction; and a corresponding one of the first front-side convex portions14. In the second front-side flow paths21a, the second front-side protruding portions26are disposed. The first front-side flow paths11aand the second front-side flow paths21aare alternately arranged in the stacking direction. The first back-side flow paths11band the second back-side flow paths21bare alternately arranged in the stacking direction. When the interval between the centers of two adjacent ones of the second front-side flow paths21ais defined as one, the number of pitches of the second front-side flow paths21ais preferably 40 or more, more preferably 80 or more, still more preferably 140 or more. When the interval between the centers of two adjacent ones of the second back-side flow paths21bis defined as one, the number of pitches of the second back-side flow paths21bis preferably 40 or more, more preferably 80 or more, still more preferably 140 or more.

In the first front-side flow paths11a, two of the first front-side protruding portions16that are adjacent with each other in the flow path width direction are arranged with a gap in the flow path width direction. When the size of the gap between the two first front-side protruding portions16adjacent in the flow path width direction is defined as W1; and the width of the second back-side convex portions25along the flow path width direction is defined as W2; the relationship W2>W1is satisfied. The size W1of the gap between two of the first front-side protruding portions16adjacent in the flow path width direction is smaller than the width W2of the second back-side convex portions25along the flow path width direction. In the second front-side flow paths21a, two of the second front-side protruding portions26that are adjacent with each other in the flow path width direction are arranged with a gap in the flow path width direction. When the size of the gap between the two second front-side protruding portions26adjacent in the flow path width direction is defined as W3and the width of the first back-side convex portions15along the flow path width direction is defined as W4, the relationship W4>W3is satisfied. The size W3of the gap between two of the second front-side protruding portions26adjacent in the flow path width direction is smaller than a width W4of the first back-side convex portions15along the flow path width direction.

FIG.5is a partially enlarged plan view illustrating the first front-side protruding portions16and the second front-side protruding portions26. Since the first front-side protruding portions16and the second front-side protruding portions26have the same structure, both of the reference signs of the first front-side protruding portions16and the second front-side protruding portions26are provided together inFIG.5. InFIG.5, the regions of the first front-side protruding portions16and the second front-side protruding portions26are clarified by dot hatching. As illustrated inFIG.5, the plurality of first front-side protruding portions16are provided at intervals along the flow path length direction. The first front-side protruding portions16provided at one end, in the flow path width direction, of each of the first front-side convex portions14and the first front-side protruding portions16provided at the opposite end of the first front-side convex portion14are disposed at the same positions in the flow path length direction. The plurality of second front-side protruding portions26are provided at intervals along the flow path length direction. The second front-side protruding portions26provided at one end, in the flow path width direction, of each of the second front-side convex portions24and the second front-side protruding portions26provided at the opposite end of the second front-side convex portion24are disposed at the same positions in the flow path length direction.

Next, a method of manufacturing the heat exchange element100will be described with reference toFIGS.1to4. The method of manufacturing the heat exchange element100illustrated inFIG.1includes a forming process, a trimming process, and a stacking process. In the forming process, by vacuum forming, hot press forming, or the like: the first corrugated portion11, the first header portion12, the second header portion13illustrated inFIG.2, and the first front-side protruding portions16illustrated inFIG.4are integrally formed; and the second corrugated portion21, the third header portion22, the fourth header portion23illustrated inFIG.3, and the second front-side protruding portions26illustrated inFIG.4are integrally formed. In the trimming process, the formed first heat transfer plate1and second heat transfer plate2are trimmed to adjust the outer shapes thereof. In the stacking process, as illustrated inFIG.1, the first heat transfer plates1and the second heat transfer plates2are stacked alternately. In addition, in the stacking process, in order to prevent the two air flows5and6from being mixed with the same flow path3or4, a joining process of joining the first heat transfer plates1and the second heat transfer plates2is performed. In the joining process, it is desirable to perform adhesion using an adhesive or a welding process using heat, ultrasonic waves, or the like. To each of the six corners of the heat exchange element100manufactured through the above-described processes, a frame (not illustrated) formed of resin is attached. By filling a gap between the heat exchange element100and the frame with a sealing agent, it is possible to prevent the two air flows5and6from entering the gap between the heat exchange element100and the frame, and prevent mixture of the two air flows5and6in the heat exchange element100.

Next, effects of the heat exchange element100will be described.

As illustrated inFIG.4, in the first embodiment, at both ends of each of the first front-side convex portions14in the flow path width direction, there are provided the first front-side protruding portions16that protrude toward the other first front-side convex portions14adjacent in the flow path width direction. The first front-side protruding portions16are contactable with the second heat transfer plates2that are adjacent to the first heat transfer plate1in the +X direction in the stacking direction. Therefore, when the plurality of first heat transfer plates1and the plurality of second heat transfer plates2are stacked, the first front-side protruding portions16of the first heat transfer plates1can support the second back-side convex portions25of the second heat transfer plates2. As a result, deformation of the first corrugated portions11can be suppressed, and falling of the second back-side convex portions25into the first front-side flow paths11acan be suppressed, so that it is possible to suppress blockage or excessive open of the first partial flow paths31and the fourth partial flow paths41. Therefore, it is possible: to suppress variations in pressure loss among the plurality of first partial flow paths31; and to suppress variations in pressure loss among the plurality of fourth partial flow paths41, so that it is possible to improve heat exchange efficiency of the heat exchange element100.

In the first embodiment, at both ends of each of the second front-side convex portions24in the flow path width direction, there are provided the second front-side protruding portions26that protrude toward the other second front-side convex portions24adjacent in the flow path width direction. The second front-side protruding portions26are contactable with the first heat transfer plates1that are adjacent to the second heat transfer plate2in the +X direction in the stacking direction. Therefore, when the plurality of first heat transfer plates1and the plurality of second heat transfer plates2are stacked, the second front-side protruding portions26of the second heat transfer plates2can support the first back-side convex portions15of the first heat transfer plates1. As a result, deformation of the second corrugated portions21can be suppressed, and falling of the first back-side convex portions15into the second front-side flow paths21acan be suppressed, so that it is possible to suppress blockage or excessive open of the first partial flow paths31and the fourth partial flow paths41. Therefore, it is possible: to suppress variations in pressure loss among the plurality of first partial flow paths31; and to suppress variations in pressure loss among the plurality of fourth partial flow paths41, so that it is possible to improve heat exchange efficiency of the heat exchange element100.

In the first embodiment, the size W1of the gap between two of the first front-side protruding portions16adjacent in the flow path width direction is smaller than the width W2of the second back-side convex portions25along the flow path width direction. Such a size relationship enables reliable support of each of the second back-side convex portions25by the two first front-side protruding portions16, and thus can further suppress falling of the second back-side convex portions25into the first front-side flow paths11a. In addition, in the first embodiment, the size W3of the gap between two of the second front-side protruding portions26adjacent in the flow path width direction is smaller than the width W4of the first back-side convex portions15along the flow path width direction. Such a size relationship enables reliable support of each of the first back-side convex portion15by the two second front-side protruding portions26, and thus can further suppress falling of the first back-side convex portions15into the second front-side flow paths21a.

In the first embodiment, the first front-side protruding portions16are provided within a range from the middle between the apex portions14aof the first front-side convex portions14and the apex portions15aof the first back-side convex portions15to the apex portions14aof the first front-side convex portions14in the stacking direction. Therefore, the first front-side protruding portions16can reliably support the second back-side convex portions25, and thus falling of the second back-side convex portions25into the first front-side flow paths11acan be further suppressed. In addition, in the first embodiment, the second front-side protruding portion26is provided within a range from the middle between the apex portions24aof the second front-side convex portions24and the apex portions25aof the second back-side convex portions25to the apex portions24aof the second front-side convex portions24in the stacking direction. Therefore, the second front-side protruding portions26can reliably support the first back-side convex portions15, and thus falling of the first back-side convex portions15into the second front-side flow paths21acan be further suppressed.

In the first embodiment, the first front-side protruding portions16and the second front-side protruding portions26are hollow, so that it is possible to suppress an increase in weight due to the provision of the first front-side protruding portions16and the second front-side protruding portions26.

In the first embodiment, the smaller the first front-side protruding portions16formed to have a symmetrical shape in the stacking direction, the larger the flow path cross-sectional area of the first front-side flow paths11acan be secured, and the pressure loss in the first front-side flow paths11acan be suppressed. In addition, the first front-side protruding portions16having a symmetrical shape in the stacking direction can have a cross-sectional area smaller than that of the first front-side protruding portions16having an asymmetrical shape in the stacking direction. Therefore, it is possible to secure a large flow path cross-sectional area of the first front-side flow paths11a, and to suppress pressure loss in the first front-side flow paths11a.

In the first embodiment, the smaller the second front-side protruding portions26formed to have a symmetrical shape in the stacking direction, the larger the flow path cross-sectional area of the second front-side flow paths21acan be secured, and the pressure loss in the second front-side flow paths21acan be suppressed. In addition, the second front-side protruding portions26having a symmetrical shape in the stacking direction can have a cross-sectional area smaller than that of the second front-side protruding portions26having an asymmetrical shape in the stacking direction. Therefore, it is possible: to secure a large flow path cross-sectional area of the second front-side flow paths21a; and to suppress pressure loss in the second front-side flow paths21a.

In the first embodiment, the heat exchange element100having a hexagonal columnar shape is exemplified, but it is not intended to limit the shape of the heat exchange element100. That is, the heat exchange element100having a shape other than the hexagonal columnar shape may be used. Further, in the first embodiment, the example in which the first front-side protruding portions16are provided at both ends of each of the first front-side convex portions14in the flow path width direction is illustrated, but the first front-side protruding portion16may be provided at at least one of both ends of the first front-side convex portion14in the flow path width direction and the opposite end may be flat. When the first front-side protruding portions16are formed in this way, the first front-side protruding portions16can suppress falling of the second back-side convex portions25, and pressure loss in the first front-side flow paths11acan be also suppressed since the first front-side protruding portions16are not provided at the opposite ends of the first front-side convex portions14in the flow path width direction. Further, in the first embodiment, the example in which the second front-side protruding portions26are provided at both ends of each of the second front-side convex portion24in the flow path width direction is illustrated, but the second front-side protruding portion26may be provided at at least one end of both ends in the flow path width direction of the second front-side convex portion24and the opposite end may be flat. When the second front-side protruding portions26are formed in this way, the second front-side protruding portions26can suppress falling of the first back-side convex portions15, and pressure loss in the second front-side flow paths21acan be also suppressed since the second front-side protruding portions26are not provided at the opposite ends of the second front-side convex portions24in the flow path width direction.

Next, a heat exchange element100A according to a first modification of the first embodiment will be described with reference toFIG.6.FIG.6is a partially enlarged plan view illustrating first front-side protruding portions16A or second front-side protruding portions26A of the heat exchange element100A according to the first modification of the first embodiment. Since the first front-side protruding portions16A of a first heat transfer plate1A and the second front-side protruding portions26A of a second heat transfer plate2A have the same structure, both of the reference signs of the first front-side protruding portions16A and the second front-side protruding portions26A are provided together inFIG.6. InFIG.6, the regions of the first front-side protruding portions16A and the second front-side protruding portions26A are clarified by dot hatching. The heat exchange element100A according to the first modification is different from the heat exchange element100according to the first embodiment described above in arrangement of the first front-side protruding portions16A and the second front-side protruding portions26A. In the first modification, portions that are duplicate of portions of the heat exchange element100of the above-described first embodiment are denoted by the same reference signs, and description thereof is omitted.

The plurality of first front-side protruding portions16A are provided at intervals along the flow path length direction. The first front-side protruding portions16A provided at one end, in the flow path width direction, of each of first front-side convex portions14A and the first front-side protruding portions16A provided at the opposite end of the first front-side convex portions14A are disposed alternately in the flow path length direction. The first front-side protruding portions16A provided at one end, in the flow path width direction, of each of the first front-side convex portions14A and the first front-side protruding portions16A provided at the opposite end of the first front-side convex portions14A are misaligned from each other in the flow path length direction.

The plurality of second front-side protruding portions26A are provided at intervals along the flow path length direction. The second front-side protruding portions26A provided at one end, in the flow path width direction, of each of second front-side convex portions24A and the second front-side protruding portions26A provided at the opposite end of the second front-side convex portions24A are disposed alternately in the flow path length direction. The second front-side protruding portions26A provided at one end, in the flow path width direction, of each of the second front-side convex portions24A and the second front-side protruding portions26A provided at the opposite end of the second front-side convex portions24A are misaligned from each other in the flow path length direction.

In the first modification, the first front-side protruding portions16A provided at one end, in the flow path width direction, of each of the first front-side convex portions14A and the first front-side protruding portions16A provided at the opposite end of the first front-side convex portions14A are alternately arranged in the flow path length direction, so that the positions of the first front-side protruding portions16A can be dispersed in the flow path length direction. Therefore, in a case where the first corrugated portion11and the first front-side protruding portions16A are integrally formed using a resin sheet as a base material, shape distortion of the entire first heat transfer plate1A can be suppressed, and falling of the second back-side convex portions25(not illustrated) can be further suppressed by the first front-side protruding portions16A. In addition, in the first modification, the second front-side protruding portions26A provided at one end, in the flow path width direction, of each of the second front-side convex portions24A and the second front-side protruding portions26A provided at the opposite end of the second front-side convex portions24A are alternately arranged in the flow path length direction, so that the positions of the second front-side protruding portions26A can be dispersed in the flow path length direction. Therefore, in a case where the second corrugated portion21and the second front-side protruding portions26A are integrally formed using a resin sheet as a base material, shape distortion of the entire second heat transfer plate2A can be suppressed, and falling of the first back-side convex portions15(not illustrated) can be further suppressed by the second front-side protruding portions26A.

Next, a heat exchange element100B according to a second modification of the first embodiment will be described with reference toFIG.7.FIG.7is a partially enlarged plan view illustrating first front-side protruding portions16B or second front-side protruding portions26B of the heat exchange element100B according to the second modification of the first embodiment. Since the first front-side protruding portions16B of a first heat transfer plate1B and the second front-side protruding portions26B of a second heat transfer plate2B have the same structure, both of the reference signs of the first front-side protruding portions16B and the second front-side protruding portions26B are provided together inFIG.7. InFIG.7, the regions of the first front-side protruding portions16B and the second front-side protruding portions26B are clarified by dot hatching. The heat exchange element100B according to the second modification is different from the heat exchange element100according to the first embodiment described above in shapes of the first front-side protruding portions16B and the second front-side protruding portions26B. In the second modification, portions that are duplicate of portions of the heat exchange element100of the above-described first embodiment are denoted by the same reference signs, and description thereof is omitted.

One of the first front-side protruding portions16B is provided at each of one end and the opposite end of each of first front-side convex portions14B in the flow path width direction. The first front-side protruding portions16B extend over the entire length of the first front-side convex portions14B in the flow path length direction. One of the second front-side protruding portions26B is provided at each of one end and the opposite end of each of second front-side convex portions24B in the flow path width direction. The second front-side protruding portions26B extend over the entire length of the second front-side convex portions24B in the flow path length direction.

In the second modification, the first front-side protruding portions16B extend over the entire length of the first front-side convex portions14B in the flow path length direction, so that it is possible to suppress partial falling of the second back-side convex portions25(not illustrated) into the first front-side flow paths11a. In addition, in the second modification, the second front-side protruding portions26B extend over the entire length of the second front-side convex portions24B in the flow path length direction, so that it is possible to suppress partial falling of the first back-side convex portions15(not illustrated) into the second front-side flow paths21a.

Next, a heat exchange element100C according to a third modification of the first embodiment will be described with reference toFIG.8.FIG.8is a cross-sectional view illustrating first front-side protruding portions16C or second front-side protruding portions26C of the heat exchange element100C according to the third modification of the first embodiment. Since the first front-side protruding portions16C of a first heat transfer plate1C and the second front-side protruding portions26C of a second heat transfer plate2C have the same structure, both of reference signs of the first front-side protruding portions16C and the second front-side protruding portions26C are provided together inFIG.8. The heat exchange element100C according to the third modification is different from the heat exchange element100according to the first embodiment described above in shapes of the first front-side protruding portions16C and the second front-side protruding portions26C. In the third modification, portions that are duplicate of portions of the heat exchange element100of the above-described first embodiment are denoted by the same reference signs, and description thereof is omitted.

The first front-side protruding portions16C each include: a first inclined portion18ahaving a protruding amount that increases from one side toward the opposite side in the stacking direction; and a second inclined portion18bhaving a protruding amount that decreases from an apex portion18ctoward the opposite side in the stacking direction. The apex portion18cis the most protruding portion of the first inclined portion18a. The first front-side protruding portion16C is formed to have an asymmetric shape in which a length of the second inclined portion18balong the stacking direction is larger than a length of the first inclined portion18aalong the stacking direction. The first front-side protruding portions16C are hollow. The plate thickness of first front-side convex portions14C including the first front-side protruding portions16C is uniform.

The second front-side protruding portions26C each include a first inclined portion28ahaving a protruding amount that increases from one side toward the opposite side in the stacking direction and a second inclined portion28bhaving a protruding amount that decreases from an apex portion28ctoward the opposite side in the stacking direction. The apex portion28cis the most protruding portion of the first inclined portion28a. The second front-side protruding portion26C is formed to have an asymmetric shape in which a length of the second inclined portion28balong the stacking direction is larger than a length of the first inclined portion28aalong the stacking direction. The second front-side protruding portions26C are hollow. The plate thickness of second front-side convex portions24C including the second front-side protruding portions26C is uniform.

In the third modification, the first front-side protruding portions16C each include: the first inclined portion18ahaving a protruding amount that increases from one side toward the opposite side in the stacking direction; and the second inclined portion18bhaving a protruding amount that decreases from the most protruding portion of the first inclined portion18atoward the opposite side in the stacking direction. The first front-side protruding portion16C is formed to have an asymmetric shape in which a length of the second inclined portion18balong the stacking direction is larger than a length of the first inclined portion18aalong the stacking direction. As a result, the position of the apex portions18cof the first front-side protruding portions16C can be brought close to the apex portions14aof the first front-side convex portions14C in the stacking direction, so that it is possible to suppress falling of the second back-side convex portions25(not illustrated) supported by the first front-side protruding portions16C. In addition, since the position of the apex portions18cof the first front-side protruding portions16C can be brought close to the apex portions14aof the first front-side convex portions14C in the stacking direction, the buckling strength of the first front-side convex portions14C against the stacking load applied from one side to the opposite side in the stacking direction can be improved to enhance the rigidity of the first front-side convex portions14C.

Further, in the third modification, the second front-side protruding portions26C each include: the first inclined portion28ahaving a protruding amount that increases from one side toward the opposite side in the stacking direction; and the second inclined portion28bhaving a protruding amount that decreases from the most protruding portion of the first inclined portion28atoward the opposite side in the stacking direction. The second front-side protruding portion26C is formed to have an asymmetric shape in which a length of the second inclined portion28balong the stacking direction is larger than a length of the first inclined portion28aalong the stacking direction. As a result, the position of the apex portions28cof the second front-side protruding portions26C can be brought close to the apex portions24aof the second front-side convex portions24C in the stacking direction, so that it is possible to suppress falling of the first back-side convex portions15(not illustrated) supported by the second front-side protruding portions26C. In addition, since the position of the apex portions28cof the second front-side protruding portions26C can be brought close to the apex portions24aof the second front-side convex portions24C in the stacking direction, the buckling strength of the second front-side convex portions24C against the stacking load applied from one side to the opposite side in the stacking direction can be improved to enhance the rigidity of the second front-side convex portions24C. In the third modification, the first front-side protruding portions16C and the second front-side protruding portions26C are hollow, so that it is possible to suppress an increase in weight due to the provision of the first front-side protruding portions16C and the second front-side protruding portions26C.

Next, a heat exchange element100D according to a fourth modification of the first embodiment will be described with reference toFIG.9.FIG.9is a cross-sectional view illustrating first front-side protruding portions16D and second front-side protruding portions26D of the heat exchange element100D according to the fourth modification of the first embodiment. Since the first front-side protruding portions16D of a first heat transfer plate1D and the second front-side protruding portions26D of a second heat transfer plate2D have the same structure, both of reference signs of the first front-side protruding portions16D and the second front-side protruding portions26D are provided together inFIG.9. The heat exchange element100D according to the fourth modification is different from the heat exchange element100according to first embodiment described above in shapes of the first front-side protruding portions16D and the second front-side protruding portions26D. In the fourth modification, portions that are duplicate of portions of the heat exchange element100of the above-described first embodiment are denoted by the same reference signs, and description thereof is omitted.

The first front-side protruding portions16D are formed to have a symmetrical shape in the stacking direction. In the fourth modification, the shape of the first front-side protruding portions16D is a solid semicircular shape that is convex toward the other first front-side convex portions14D adjacent in the flow path width direction. The portions of the first front-side convex portions14D where the first front-side protruding portions16D are formed have a plate thickness larger than the other portions. The plate thickness of the first front-side convex portions14D is changed partially.

The second front-side protruding portions26D are formed to have a symmetrical shape in the stacking direction. In the fourth modification, the shape of the second front-side protruding portions26D is a solid semicircular shape that is convex toward the other second front-side convex portions24D adjacent in the flow path width direction. The portions of the second front-side convex portions24D where the second front-side protruding portions26D are formed have a plate thickness larger than the other portions. The plate thickness of the second front-side convex portions24D is changed partially.

In the fourth modification, the first front-side protruding portions16D are solid, so that the rigidity of the first front-side protruding portions16D can be enhanced. In addition, in the fourth modification, the second front-side protruding portions26D are solid, so that the rigidity of the second front-side protruding portions26D can be enhanced.

Next, a heat exchange element100E according to a fifth modification of the first embodiment will be described with reference toFIG.10.FIG.10is a cross-sectional view illustrating first front-side protruding portions16E and second front-side protruding portions26E of the heat exchange element100E according to the fifth modification of the first embodiment. Since the first front-side protruding portions16E of the first heat transfer plate1E and the second front-side protruding portions26E of the second heat transfer plate2E have the same structure, both of reference signs of the first front-side protruding portions16E and the second front-side protruding portions26E are provided together inFIG.10. The heat exchange element100E according to the fifth modification is different from the heat exchange element100according to first embodiment described above in shapes of the first front-side protruding portions16E and the second front-side protruding portions26E. In the fifth modification, portions that are duplicate of portions of the heat exchange element100of the above-described first embodiment are denoted by the same reference signs, and description thereof is omitted.

The first front-side protruding portions16E each include: a first inclined portion19ahaving a protruding amount that increases from one side toward the opposite side in the stacking direction; and a second inclined portion19bhaving a protruding amount that decreases from an apex portion19ctoward the opposite side in the stacking direction. The apex portion19cis the most protruding portion of the first inclined portion19a. The first front-side protruding portion16E is formed to have an asymmetric shape in which a length of the second inclined portion19balong the stacking direction is larger than a length of the first inclined portion19aalong the stacking direction. The first front-side protruding portions16E are solid. In the first front-side convex portions14E, the first front-side protruding portions16E have a plate thickness larger than the thickness of the other portions. The plate thickness of the first front-side convex portions14E is changed partially.

The second front-side protruding portions26E each include a first inclined portion29ahaving a protruding amount that increases from one side toward the opposite side in the stacking direction and a second inclined portion29bhaving a protruding amount that decreases from an apex portion29ctoward the opposite side in the stacking direction. The apex portion29cis the most protruding portion of the first inclined portion29a. The second front-side protruding portion26E is formed to have an asymmetric shape in which a length of the second inclined portion29balong the stacking direction is larger than a length of the first inclined portion29aalong the stacking direction. The second front-side protruding portions26E are solid. In the front-side convex portions24E, the second front-side protruding portions26E have a plate thickness larger than the other portions. The plate thickness of the second front-side convex portions24E is changed partially.

In the fifth modification, the first front-side protruding portions16E each include: a first inclined portion19ahaving a protruding amount that increases from one side toward the opposite side in the stacking direction; and a second inclined portion19bhaving a protruding amount that decreases from an apex portion19ctoward the opposite side in the stacking direction. The apex portion19cis the most protruding portion of the first inclined portion19a. The first front-side protruding portion16E is formed to have an asymmetric shape in which a length of the second inclined portion19balong the stacking direction is larger than a length of the first inclined portion19aalong the stacking direction. As a result, the position of the apex portions19cof the first front-side protruding portion16E can be brought close to the apex portions14aof the first front-side convex portion14E in the stacking direction, so that it is possible to suppress falling of the second back-side convex portions25(not illustrated) supported by the first front-side protruding portions16E. In addition, since the position of the apex portions19cof the first front-side protruding portions16E can be brought close to the apex portions14aof the first front-side convex portions14E in the stacking direction, the buckling strength of the first front-side convex portions14E against the stacking load applied from one side to the opposite side in the stacking direction can be improved to enhance the rigidity of the first front-side convex portions14E. Furthermore, in the fifth modification, the first front-side protruding portions16E are solid, so that the rigidity of the first front-side protruding portions16E can be further enhanced.

Further, in the fifth modification, the second front-side protruding portions26E each include: the first inclined portion29ahaving a protruding amount that increases from one side toward the opposite side in the stacking direction; and the second inclined portion29bhaving a protruding amount that decreases from an apex portion29ctoward the opposite side in the stacking direction. The apex portion29cis the most protruding portion of the first inclined portion29a. The second front-side protruding portions26E are formed to have an asymmetric shape in which a length of the second inclined portion29balong the stacking direction is larger than a length of the first inclined portion29aalong the stacking direction. As a result, the position of the apex portions29cof the second front-side protruding portions26E can be brought close to the apex portions24aof the second front-side convex portions24E in the stacking direction, so that it is possible to suppress falling of the first back-side convex portions15(not illustrated) supported by the second front-side protruding portions26E. In addition, since the position of the apex portions29cof the second front-side protruding portions26E can be brought close to the apex portions24aof the second front-side convex portions24E in the stacking direction, the buckling strength of the second front-side convex portions24E against the stacking load applied from one side to the opposite side in the stacking direction can be improved to enhance the rigidity of the second front-side convex portions24E. In addition, in the fifth modification, the second front-side protruding portions26E are solid, so that the rigidity of the second front-side protruding portions26E can be further enhanced.

Second Embodiment

Next, a heat exchange element100F according to a second embodiment will be described with reference to FIG.11.FIG.11is a cross-sectional view illustrating the heat exchange element100F according to the second embodiment and is a view corresponding to the cross-sectional view taken along line IV-IV inFIGS.2and3. The second embodiment is different from the first embodiment described above in that: first heat transfer plates1F include first back-side protruding portions17; and second heat transfer plates2F include second back-side protruding portions27. In the second embodiment, portions that are duplicate of portions of the above-described first embodiment are denoted by the same reference signs, and description thereof is omitted.

At both ends of each of the first back-side convex portions15in the flow path width direction, there are provided the first back-side protruding portions17that protrude toward the other first back-side convex portions15adjacent in the flow path width direction. The first back-side protruding portions17are contactable with the second heat transfer plates2F adjacent to the first heat transfer plate1F in the −X direction in the stacking direction. The first back-side protruding portions17are supported by corresponding one of the second front-side convex portions24of the second heat transfer plate2F. The first back-side protruding portions17are preferably provided in a range from the middle between the apex portions15aof the first back-side convex portions15and the apex portions14aof the first front-side convex portions14to the apex portions15aof the first back-side convex portion15in the stacking direction, and more preferably at a position close to the apex portions15aof the first back-side convex portion15in the stacking direction. The first back-side protruding portions17do not protrude from the apex portions15aof the first back-side convex portions15in the −X direction in the stacking direction. The shape of the first back-side protruding portions17is not particularly limited, but is, in the second embodiment, a solid semicircular shape that is convex toward other ones, adjacent in the flow path width direction, of the first back-side convex portions15.

At both ends of each of the second back-side convex portions25in the flow path width direction, there are provided the second back-side protruding portions27that protrude toward the other second back-side convex portions25adjacent in the flow path width direction. The second back-side protruding portions27are contactable with the first heat transfer plates1F adjacent to the second heat transfer plate2F in the −X direction in the stacking direction. The second back-side protruding portions27are supported by corresponding one of the first front-side convex portions14of the first heat transfer plate1F. The second back-side protruding portions27are preferably provided in a range from the middle between the apex portions25aof the second back-side convex portion25and the apex portions24aof the second front-side convex portions24to the apex portions25aof the second back-side convex portions25in the stacking direction, and more preferably at a position close to the apex portions25aof the second back-side convex portions25in the stacking direction. The second back-side protruding portions27do not protrude from the apex portions25aof the second back-side convex portions25in the −X direction in the stacking direction. The shape of the second back-side protruding portions27is not particularly limited, but is, in the second embodiment, a solid semicircular shape that is convex toward other ones, adjacent in the flow path width direction, of the second back-side convex portions25.

Although not illustrated, a die for manufacturing the first heat transfer plates1F and the second heat transfer plates2F has recesses for forming the first back-side protruding portions17and the second back-side protruding portions27. Compressed air is blown into the die to cause the resin sheet to lay along the recesses of the die. Although the portions of the resin sheet laying along the recesses of the die, that is, the first back-side protruding portions17and the second back-side protruding portions27are undercuts, formed articles can be removed from the die by forced removal because thin resin sheets are used as the base materials of the first heat transfer plate1F and the second heat transfer plate2F in the second embodiment.

In the second embodiment, at both ends of each of the first back-side convex portions15in the flow path width direction, there are provided the first back-side protruding portions17that protrude toward the other first back-side convex portions15adjacent in the flow path width direction. The first back-side protruding portions17are contactable with the second heat transfer plates2F adjacent to the first heat transfer plate1F in the −X direction in the stacking direction. Therefore, when the plurality of first heat transfer plates1F and the plurality of second heat transfer plates2F are stacked, the second front-side convex portions24of the second heat transfer plates2F can reliably support the first back-side convex portions15of the first heat transfer plates1F. As a result, deformation of the first corrugated portions11can be suppressed, and falling of the first back-side convex portions15into the second front-side flow paths21acan be suppressed, so that it is possible to suppress blockage or excessive open of the first partial flow paths31and the fourth partial flow paths41. Therefore, it is possible to suppress variations in pressure loss among the plurality of first partial flow paths31, and to suppress variations in pressure loss among the plurality of fourth partial flow paths41, so that it is possible to improve heat exchange efficiency of the heat exchange element100F.

In the second embodiment, at both ends of each of the second back-side convex portions25in the flow path width direction, there are provided the second back-side protruding portions27that protrude toward the other second back-side convex portions25adjacent in the flow path width direction. The second back-side protruding portions27are contactable with the first heat transfer plates1F adjacent to the second heat transfer plate2F in the −X direction in the stacking direction. Therefore, when the plurality of first heat transfer plates1F and the plurality of second heat transfer plates2F are stacked, the first front-side convex portions14of the first heat transfer plates1F can reliably support the second back-side convex portions25of the second heat transfer plates2F. As a result, deformation of the second corrugated portions21can be suppressed, and falling of the second back-side convex portions25into the first front-side flow paths11acan be suppressed, so that it is possible to suppress blockage or excessive open of the first partial flow paths31and the fourth partial flow paths41. Therefore, it is possible to suppress variations in pressure loss among the plurality of first partial flow paths31, and to suppress variations in pressure loss among the plurality of fourth partial flow paths41, so that it is possible to improve heat exchange efficiency of the heat exchange element100F.

In the second embodiment, the example in which the first back-side protruding portions17are provided at both ends of each of the first back-side convex portions15in the flow path width direction is illustrated, but the first back-side protruding portion17may be provided at at least one of both ends of the first back-side convex portion15in the flow path width direction and the opposite end may be flat. When the first back-side protruding portions17are formed in this way, the first back-side protruding portions17can suppress falling of the first back-side convex portions15, and pressure loss in the first back-side flow paths11bcan be also suppressed since the first back-side protruding portions17are not provided at the opposite ends of the first back-side convex portions15in the flow path width direction. Further, in the second embodiment, the example in which the second back-side protruding portions27are provided at both ends of each of the second back-side convex portions25in the flow path width direction is illustrated, but the second back-side protruding portion27may be provided at at least one end of both ends of the second back-side convex portion25in the flow path width direction and the opposite end may be flat. When the second back-side protruding portions27are formed in this way, the second back-side protruding portion27can suppress falling of the second back-side convex portions25, and pressure loss in the second back-side flow paths21bcan be suppressed since the second back-side protruding portions27are not provided at the opposite ends of the second back-side convex portions25in the flow path width direction.

The configurations described in the above-described embodiments provide examples, and any of the configurations can be combined with another known technique, the embodiments can be combined with each other, or a part of the configurations can be eliminated or changed without departing from the gist of the present invention.

REFERENCE SIGNS LIST