Heat exchange member and heat exchanger

Abstract

To efficiently perform heat exchange between a first fluid and a second fluid while suppressing an increase in the temperature of a heat exchange member.SOLUTION: A heat exchange member 5 at least comprises a first honeycomb structure 1 and a second honeycomb structure. The second honeycomb structure is arranged in series on the downstream side of the first honeycomb structure 1. An internal space 100 of a first outer peripheral wall 11 comprises an outer region 101 and an inner region 102. In the outer region 101, first outer cells 15 are peripherally arranged at a prescribed cell density along an inner peripheral surface of the first outer peripheral wall 11. In the inner region 102, the cell density of first inner cells 16 is lower than that in the outer region 101. The heat exchange member 5 performs heat exchange between a first fluid flowing through a plurality of first cells 17 and a plurality of second cells, and a second fluid having a temperature lower than that of the first fluid. This enables efficiently performing heat exchange between the first fluid and the second fluid while suppressing an increase in the temperature of the heat exchange member 5.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a heat exchange member and a heat exchanger. [Background technology]

[0002] In recent years, there has been a demand for improved fuel efficiency in automobiles. For example, to improve fuel efficiency when the engine temperature is low, such as when the engine is started, there is a demand for technology that can quickly heat engine oil and automatic transmission fluid (ATF) and reduce friction loss. There is also a demand for technology that can quickly heat up catalysts for purifying exhaust gases in order to quickly activate them. In addition to automobiles, there is also a demand for technology that can quickly heat up catalysts in order to quickly activate them. In addition to automobiles, there are also many factories, such as metal factories, ceramic factories, pulp and paper factories, chemical factories, and food factories, that are working to reduce CO2 emissions in order to become carbon neutral. 2 From the perspective of reduction and energy conservation measures, there is a demand for effective use of the thermal energy contained in exhaust gases, hot water, steam, etc.

[0003] To meet these technical demands, for example, heat exchangers are used. In the heat exchangers, heat is recovered from a high-temperature fluid (e.g., exhaust gas) and transferred to a low-temperature fluid (e.g., cooling water). The heat transferred to the cooling water or the like is utilized for various purposes as described above.

[0004] As a heat exchange member used in such a heat exchanger, for example, a cylindrical ceramic body that is a honeycomb structure in which a large number of cells are formed by partition walls is used (Patent Document 1). In this heat exchanger, a high-temperature first fluid is circulated inside the cylindrical ceramic body, and a low-temperature second fluid is circulated outside the cylindrical ceramic body, and heat exchange is performed between the first fluid and the second fluid. Patent Document 2 also proposes a heat exchange member in which two or more honeycomb structures are arranged in series. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-165181 A [Patent Document 2] International Publication No. 2012 / 064814 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the temperature of the first fluid flowing inside the heat exchange member becomes high, the temperature of the heat exchange member that recovers heat from the first fluid increases excessively, which may damage the heat exchange member. For this reason, the temperature of the first fluid that can recover heat in the heat exchanger is limited. On the other hand, when the heat recovery from the first fluid in the heat exchange member is suppressed, the efficiency of heat exchange between the first fluid and the second fluid decreases.

[0007] The present invention has been made in consideration of the above problems, and has an object to efficiently exchange heat between a first fluid and a second fluid while suppressing a temperature rise in a heat exchange member. [Means for solving the problem]

[0008] A first aspect of the present invention is a heat exchange member, comprising at least a first honeycomb structure having a cylindrical first peripheral wall and a first partition wall that divides an internal space of the first peripheral wall to form a plurality of first cells extending in an axial direction, and a second honeycomb structure having a cylindrical second peripheral wall and a second partition wall that divides an internal space of the second peripheral wall to form a plurality of second cells extending in an axial direction. Each of the first cells is a flow path through which a first fluid flows from an upstream side, which is one side of the first honeycomb structure, to a downstream side, which is the other side, in the axial direction. The second honeycomb structure is disposed in series on the downstream side of the first honeycomb structure and is connected to the first honeycomb structure in a state in which the entire amount of the first fluid that has passed through the first cells flows in. Each of the second cells is a flow path through which the first fluid flows in from the first honeycomb structure. The internal space of the first outer peripheral wall includes an outer region in which first cells are circumferentially arranged at a predetermined cell density along an inner peripheral surface of the first outer peripheral wall, and an inner region surrounded by the outer region inside the outer region and having a lower cell density of the first cells than the outer region. The heat exchange member exchanges heat between the first fluid flowing through the plurality of first cells and the plurality of second cells and a second fluid having a lower temperature than the first fluid flowing outside the first outer peripheral wall and the second outer peripheral wall.

[0009] A second aspect of the present invention is a heat exchanger element of the first aspect, further comprising a cylindrical covering portion covering the outer peripheral surface of the first outer peripheral wall and the outer peripheral surface of the second outer peripheral wall from the upstream end of the first honeycomb structure to the downstream end of the second honeycomb structure.

[0010] A third aspect of the present invention is a heat exchange member of the first aspect (which may be either the first or second aspect), wherein the inner region is a space formed by a single first cell having a larger cross-sectional area than each of the first cells in the outer region.

[0011] A fourth aspect of the present invention is a heat exchanger member of the first aspect (which may be any one of the first to third aspects), wherein the cross-sectional area of ​​the inner region in the upstream portion of the first honeycomb structure is larger than the cross-sectional area of ​​the inner region in the downstream portion of the first honeycomb structure.

[0012] A fifth aspect of the present invention is a heat exchanger member of the first aspect (which may be any one of the first to fourth aspects), wherein the cell density of the second cells in the vicinity of the central axis of the second honeycomb structure is higher than the cell density of the first cells in the inner region of the first honeycomb structure.

[0013] A sixth aspect of the present invention is the heat exchanger element of the first aspect (which may be any one of the first to fifth aspects), further comprising a third honeycomb structure having a cylindrical third outer peripheral wall and third partition walls that partition an internal space of the third outer peripheral wall and form a plurality of third cells extending in the axial direction. The third honeycomb structure is disposed in series on the downstream side of the second honeycomb structure and is connected to the second honeycomb structure in a state in which the entire amount of the first fluid that has passed through the plurality of second cells flows in. Each of the plurality of third cells is a flow path through which the first fluid that has flowed in from the second honeycomb structure flows.

[0014] A seventh aspect of the present invention is the heat exchanger element of the sixth aspect, wherein a cell density of the third cells in the third honeycomb structure is lower than a cell density of the second cells in the second honeycomb structure.

[0015] Aspect 8 of the present invention is a heat exchanger member of aspect 6 (which may be aspect 6 or 7), wherein a gap is provided between the downstream end face of the second honeycomb structure and the upstream end face of the third honeycomb structure.

[0016] A ninth aspect of the present invention is the heat exchanger member of the first aspect (which may be any one of the first to eighth aspects), wherein the first honeycomb structure and the second honeycomb structure are mainly made of ceramics.

[0017] A tenth aspect of the present invention is a heat exchanger comprising the heat exchange member according to any one of the first to ninth aspects and an outer wall portion covering the outer circumferential surface of the heat exchange member while being spaced outwardly from the outer circumferential surface of the heat exchange member. A space between the outer circumferential surface of the heat exchange member and the outer wall portion is a flow path through which the second fluid flows. Effect of the Invention

[0018] According to the present invention, heat exchange between the first fluid and the second fluid can be efficiently performed while suppressing a temperature rise in the heat exchange member. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view of a heat exchanger according to a first embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a front view showing a first honeycomb structure of the heat exchange member. [Figure 4] FIG. 4 is a front view showing a second honeycomb structure of the heat exchange member. [Diagram 5] FIG. 2 is a diagram illustrating a vertical cross section of a heat exchange member. [Figure 6] 4 is a graph showing the relationship between a first outer peripheral wall diameter and pressure loss. [Figure 7] 4 is a graph showing the relationship between a first outer peripheral wall diameter and a heat recovery amount. [Figure 8] 6 is a graph showing the relationship between the first inner peripheral wall diameter and the maximum temperature of the first honeycomb structure. [Figure 9] 4 is a graph showing the relationship between a first inner circumferential wall diameter and pressure loss. [Figure 10] 4 is a graph showing the relationship between the inner / outer diameter ratio and the maximum temperature of the first honeycomb structure. [Figure 11] 4 is a graph showing the relationship between the inner / outer diameter ratio and pressure loss. [Figure 12] 4 is a graph showing the relationship between the length of the first honeycomb structure and the amount of heat recovery. [Figure 13] 4 is a graph showing the relationship between the inner / outer density ratio and the maximum temperature of the first honeycomb structure. [Figure 14] FIG. 11 is a schematic diagram showing a vertical cross section of a heat exchange member according to a second embodiment. [Figure 15] FIG. 4 is a front view showing a third honeycomb structure of the heat exchange member. [Figure 16] FIG. 11 is a schematic diagram showing a vertical cross section of a heat exchange member according to a third embodiment. [Figure 17] FIG. 13 is a schematic diagram showing a vertical cross section of a heat exchange member according to a fourth embodiment. [Figure 18] FIG. 2 is a front view showing a first honeycomb structure of the heat exchange member. [Figure 19] FIG. 13 is a schematic diagram showing a vertical cross section of a heat exchange member according to a fifth embodiment. [Figure 20] FIG. 13 is a schematic diagram showing a vertical cross section of a heat exchange member according to a sixth embodiment. [Figure 21] FIG. 13 is a schematic diagram showing a vertical cross section of a heat exchange member according to a seventh embodiment. [Figure 22] FIG. 13 is a schematic diagram showing a vertical cross section of a heat exchange member according to an eighth embodiment. [Figure 23] FIG. 23 is a schematic diagram showing a vertical cross section of a heat exchange member according to a ninth embodiment. [Figure 24] FIG. 23 is a schematic diagram showing a vertical cross section of a heat exchange member according to a tenth embodiment. [Diagram 25] FIG. 23 is a schematic diagram showing a vertical cross section of a heat exchange member according to an eleventh embodiment. [Figure 26] FIG. 23 is a schematic diagram showing a vertical cross section of a heat exchange member according to a twelfth embodiment. [Figure 27] FIG. 23 is a schematic diagram showing a vertical cross section of a heat exchange member according to a thirteenth embodiment. [Figure 28] FIG. 23 is a schematic diagram showing a vertical cross section of a heat exchange member according to a fourteenth embodiment. [Figure 29] FIG. 23 is a schematic diagram showing a vertical cross section of a heat exchange member according to a fifteenth embodiment. [Diagram 30] FIG. 23 is a schematic diagram showing a vertical cross section of a heat exchange member according to a sixteenth embodiment. [Diagram 31]FIG. 11 is a schematic diagram showing a vertical cross section of another heat exchange member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] FIG. 1 is a perspective view showing a heat exchanger 7 according to a first embodiment of the present invention. The heat exchanger 7 is mounted on an automobile, for example, and used to recover heat from exhaust gas from the automobile. In FIG. 1, three mutually orthogonal directions are indicated by arrows as X direction, Y direction, and Z direction. This is the same in other figures described later. In the example shown in FIG. 1, the heat exchanger 7 is a substantially cylindrical member extending in the Y direction. The shape of the heat exchanger 7 may be changed in various ways.

[0021] The heat exchanger 7 includes an outer wall portion 6 and a heat exchange member 5 housed inside the outer wall portion 6. Fig. 2 is a perspective view showing the heat exchange member 5. Fig. 3 is a front view of the heat exchange member 5 as viewed from the (-Y) side. Fig. 4 is a front view of the heat exchange member 5 as viewed from the (-Y) side, omitting a first honeycomb structure 1 described below. In Figs. 1 and 2, first cells 17 (described below) and the like on the end face on the (-Y) side of the heat exchange member 5 are not shown.

[0022] The heat exchange member 5 is a substantially cylindrical member centered on a central axis J1 extending parallel to the Y direction. In the following description, the Y direction in which the central axis J1 extends is also referred to as the "axial direction." The heat exchange member 5 includes a first honeycomb structure 1, a second honeycomb structure 2, and a covering portion 4.

[0023] The first honeycomb structure 1 and the second honeycomb structure 2 are each a substantially cylindrical member extending substantially parallel to the Y direction about a central axis J1. The outer diameter of the first honeycomb structure 1 (i.e., the diameter of a cross section perpendicular to the central axis J1) is substantially the same at any position in the Y direction. The outer diameter of the second honeycomb structure 2 is also substantially the same at any position in the Y direction. Furthermore, the outer diameter of the first honeycomb structure 1 and the outer diameter of the second honeycomb structure 2 are substantially the same. In the example shown in FIG. 2, the length in the Y direction of the first honeycomb structure 1 and the length in the Y direction of the second honeycomb structure 2 are substantially the same.

[0024] The second honeycomb structure 2 is disposed adjacent to the (+Y) side of the first honeycomb structure 1. In other words, the first honeycomb structure 1 and the second honeycomb structure 2 are arranged in series approximately parallel to the Y direction. The end face on the (+Y) side of the first honeycomb structure 1 and the end face on the (-Y) side of the second honeycomb structure 2 may be in direct contact with each other, or may be indirectly in contact with each other via a substantially annular plate-shaped buffer material or the like that is in contact with the outer periphery of each of the end faces. As described later, in addition to the first honeycomb structure 1 and the second honeycomb structure 2, the heat exchange member 5 may be provided with other structures that are arranged in series with the first honeycomb structure 1 and the second honeycomb structure 2. That is, the heat exchange member 5 includes at least the first honeycomb structure 1 and the second honeycomb structure 2.

[0025] Inside the first honeycomb structure 1, a plurality of first cells 17 extending substantially parallel to the Y direction (i.e., the axial direction) are provided over the entire length of the first honeycomb structure 1 in the Y direction. Inside the second honeycomb structure 2, a plurality of second cells 27 extending substantially parallel to the Y direction are provided over the entire length of the second honeycomb structure 2 in the Y direction. Each of the first cells 17 and the second cells 27 is a flow path through which a fluid such as a gas, liquid, or a gas-liquid two-phase fluid (hereinafter also referred to as a "first fluid") can pass. The first fluid is, for example, exhaust gas discharged from an automobile engine.

[0026] The first honeycomb structure 1 and the second honeycomb structure 2 are each made of a material mainly composed of ceramics. This allows the first honeycomb structure 1 and the second honeycomb structure 2 to have high thermal conductivity. From the viewpoint of increasing thermal conductivity, it is preferable that the first honeycomb structure 1 and the second honeycomb structure 2 are each made of ceramics mainly composed of silicon carbide (SiC). In this specification, "mainly composed of ceramics" means that the ceramics account for 50 mass% or more. Furthermore, "ceramics mainly composed of SiC" means that the SiC content in the ceramics is 50 mass% or more.

[0027] From the viewpoint of further increasing the thermal conductivity, it is preferable that the first honeycomb structure 1 and the second honeycomb structure 2 are each formed of ceramics mainly composed of SiC impregnated with metal Si. The thermal conductivity of the first honeycomb structure 1 and the second honeycomb structure 2 increases as the amount of metal Si impregnated increases. In this specification, "ceramics mainly composed of SiC impregnated with metal Si" means that the content of SiC impregnated with metal Si in the ceramics is 50 mass % or more. The structure of the first honeycomb structure 1 and the second honeycomb structure 2 will be described in detail later.

[0028] The covering portion 4 is a substantially cylindrical member extending substantially parallel to the Y direction with the central axis J1 as its center. The outer diameter of the covering portion 4 (i.e., the diameter of the outer peripheral surface in a cross section perpendicular to the Y direction) is substantially the same at any position in the Y direction. The inner diameter of the covering portion 4 (i.e., the diameter of the inner peripheral surface in a cross section perpendicular to the Y direction) is also substantially the same at any position in the Y direction. The inner diameter of the covering portion 4 is substantially the same as the outer diameters of the first honeycomb structure 1 and the second honeycomb structure 2.

[0029] In the example shown in FIG. 2, the length of the covering portion 4 in the Y direction is longer than the total length of the first honeycomb structure 1 and the second honeycomb structure 2 in the Y direction. In other words, the length of the covering portion 4 in the Y direction is longer than the distance in the Y direction between the end face on the (-Y) side of the first honeycomb structure 1 and the end face on the (+Y) side of the second honeycomb structure 2. The covering portion 4 covers the outer peripheral surface of the first honeycomb structure 1 and the outer peripheral surface of the second honeycomb structure 2 over substantially the entire surface from the end face on the (-Y) side of the first honeycomb structure 1 to the end face on the (+Y) side of the second honeycomb structure 2. The inner peripheral surface of the covering portion 4 is in direct contact with the outer peripheral surface of the first honeycomb structure 1 and the outer peripheral surface of the second honeycomb structure 2 over substantially the entire surface. This allows the first honeycomb structure 1 and the second honeycomb structure 2 to be connected to each other. The inner peripheral surface of the covering portion 4 and the outer peripheral surface of the first honeycomb structure 1 and the outer peripheral surface of the second honeycomb structure 2 may be indirectly in contact with each other via an inclusion.

[0030] The opening on the (-Y) side of the covering portion 4 is located on the (-Y) side of the end face on the (-Y) side of the first honeycomb structure 1. The opening on the (+Y) side of the covering portion 4 is located on the (+Y) side of the end face on the (+Y) side of the second honeycomb structure 2. In other words, the covering portion 4 extends further on the (-Y) side than the first honeycomb structure 1, and extends further on the (+Y) side than the second honeycomb structure 2.

[0031] The covering portion 4 is a member that is substantially impermeable to fluids such as gas, liquid, and gas-liquid two-phase fluid. Therefore, the first fluid flowing inside the first honeycomb structure 1 and the second honeycomb structure 2 is prevented from permeating the covering portion 4 and leaking out from the outer circumferential surface of the covering portion 4. The covering portion 4 is preferably formed of a metal (e.g., stainless steel) that has high heat resistance, thermal shock resistance, and corrosion resistance, and also has high thermal conductivity. Note that the covering portion 4 may be formed of a metal other than stainless steel, or may be formed of a material other than a metal.

[0032] The outer wall 6 is a substantially cylindrical member centered on the central axis J1. As described above, the heat exchange member 5 is housed inside the outer wall 6. In the example shown in FIG. 1, the outer wall 6 is a substantially cylindrical member extending in the Y direction centered on the central axis J1. The length of the outer wall 6 in the Y direction is longer than the length of the heat exchange member 5 in the Y direction. The opening on the (-Y) side of the outer wall 6 is located on the (-Y) side of the opening on the (-Y) side of the covering portion 4 of the heat exchange member 5. The opening on the (+Y) side of the outer wall 6 is located on the (+Y) side of the opening on the (+Y) side of the covering portion 4 of the heat exchange member 5. In other words, the outer wall 6 extends to the (-Y) side and the (+Y) side of the heat exchange member 5.

[0033] The outer wall portion 6 includes an outer wall central portion 61 and two outer wall end portions 62. The two outer wall end portions 62 are airtightly and liquidtightly connected to both ends of the outer wall central portion 61 in the Y direction. The outer wall central portion 61 and the two outer wall end portions 62 are each a substantially cylindrical portion extending in the Y direction centered on the central axis J1. The inner diameter and the outer diameter of each outer wall end portion 62 are substantially the same at any position in the Y direction. The inner diameter of each outer wall end portion 62 is substantially the same as the outer diameter of the covering portion 4 of the heat exchange member 5. The inner peripheral surface of each outer wall end portion 62 is in direct contact with the outer peripheral surface of the covering portion 4 of the heat exchange member 5 over substantially the entire circumference in the circumferential direction centered on the central axis J1. The inner peripheral surface of each outer wall end portion 62 and the outer peripheral surface of the covering portion 4 may be indirectly in contact with each other via an intervening object.

[0034] In the example shown in FIG. 1, the length of the outer wall central portion 61 in the Y direction is approximately the same as the total length of the first honeycomb structure 1 and the second honeycomb structure 2 in the Y direction. The inner diameter and the outer diameter of the outer wall central portion 61 are approximately the same at any position in the Y direction. The inner diameter of the outer wall central portion 61 is larger than the outer diameter of the covering portion 4 of the heat exchange member 5. The outer wall central portion 61 covers the outer peripheral surface of the covering portion 4 over approximately the entire circumference in the circumferential direction centered on the central axis J1, in a state of being spaced from the outer peripheral surface of the covering portion 4 to the outside in the radial direction centered on the central axis J1. Between the inner peripheral surface of the outer wall central portion 61 and the outer peripheral surface of the covering portion 4 (i.e., the outer peripheral surface of the heat exchange member 5), a substantially cylindrical space 70 is provided that extends approximately parallel to the Y direction centered on the central axis J1. In the following description, the circumferential direction and the radial direction centered on the central axis J1 are also simply referred to as the "circumferential direction" and the "radial direction".

[0035] The outer wall portion 6 further includes a supply port 63 and a discharge port 64. The supply port 63 and the discharge port 64 are each a substantially tubular portion protruding outward from the outer peripheral surface of the outer wall central portion 61. The supply port 63 is disposed near the end of the outer wall central portion 61 on the (+Y) side. The discharge port 64 is disposed near the end of the outer wall central portion 61 on the (-Y) side. The supply port 63 and the discharge port 64 are connected to a space 70 between the outer wall central portion 61 and the heat exchange member 5. A fluid such as a gas, a liquid, or a gas-liquid two-phase fluid (hereinafter also referred to as a "second fluid") is supplied to the space 70 via the supply port 63. The second fluid flows through the space 70 in a state where the space 70 is filled, and is discharged to the outside of the heat exchanger 7 via the discharge port 64. That is, the space 70 is a flow path through which the second fluid flows, and hereinafter the space 70 is also referred to as a "second flow path 70". The second fluid is a fluid having a lower temperature than the first fluid, and is, for example, liquid water.

[0036] In the heat exchanger 7, the first fluid flows in from the opening on the (-Y) side of the outer wall portion 6, passes through each of the first cells 17 of the first honeycomb structure 1 and each of the second cells 27 of the second honeycomb structure 2 from the (-Y) side to the (+Y) side, and flows out from the opening on the (+Y) side of the outer wall portion 6. In detail, the first fluid that flows in from the opening on the (-Y) side of the outer wall portion 6 flows into the heat exchange member 5 through the opening on the (-Y) side of the covering portion 4, and is supplied to the end face on the (-Y) side of the first honeycomb structure 1. In the first honeycomb structure 1, the first fluid flows from the (-Y) side (hereinafter also referred to as the "upstream side"), which is one side in the axial direction of each of the first cells 17, to the (+Y) side (hereinafter also referred to as the "downstream side"), which is the other side in the axial direction.

[0037] The first fluid that has passed through the first cells 17 is supplied to the end face on the (-Y) side of the second honeycomb structure 2. Since the outer periphery of the connection between the first honeycomb structure 1 and the second honeycomb structure 2 is covered with the covering portion 4 that is impermeable to fluid, the entire amount of the first fluid that has passed through the first cells 17 flows into the second honeycomb structure 2. In the second honeycomb structure 2, the first fluid that has flowed in from the first honeycomb structure 1 flows from the (-Y) side to the (+Y) side of each second cell 27. The first fluid that has passed through the second cells 27 flows out of the heat exchange member 5 through the opening on the (+Y) side of the covering portion 4, and flows out of the heat exchanger 7 through the opening on the (+Y) side of the outer wall portion 6.

[0038] In the heat exchanger 7, heat exchange is performed between the first fluid flowing inside the heat exchange member 5 and the second fluid flowing through the second flow path 70 outside the heat exchange member 5 via the heat exchange member 5. Specifically, the first honeycomb structure 1 and the second honeycomb structure 2 are heated by the high-temperature first fluid flowing through the first cells 17 and the second cells 27, and the covering portion 4 is also heated. Then, the low-temperature second fluid flowing through the second flow path 70 while contacting the covering portion 4 (i.e., flowing outside the first peripheral wall 11 of the first honeycomb structure 1 and the second peripheral wall 21 of the second honeycomb structure 2, which will be described later) is heated. On the other hand, the temperature of the first fluid is reduced by passing through the heat exchange member 5. Note that the covering portion 4 is a member that is impermeable to the first and second fluids, so that the first fluid flowing inside the heat exchange member 5 does not leak into the second flow path 70, and the second fluid flowing through the second flow path 70 does not leak into the inside of the heat exchange member 5.

[0039] Next, the structure of the first honeycomb structure 1 and the second honeycomb structure 2 will be described in detail. As shown in FIG. 3, the first honeycomb structure 1 includes a cylindrical first outer peripheral wall 11, a cylindrical first inner peripheral wall 12, and a first partition wall 18. In the example shown in FIG. 3, the first outer peripheral wall 11 and the first inner peripheral wall 12 are each a substantially cylindrical portion extending substantially parallel to the Y direction centered on the central axis J1. The first inner peripheral wall 12 is disposed radially inside the first outer peripheral wall 11. The length in the Y direction of each of the first outer peripheral wall 11 and the first inner peripheral wall 12 is substantially the same as the total length in the Y direction of the first honeycomb structure 1. The total length in the Y direction of the first honeycomb structure 1 is, for example, 1 mm to 800 mm, and preferably 500 mm or less.

[0040] The outer diameter and inner diameter of the first outer peripheral wall 11 are substantially the same at any position in the Y direction. The outer diameter of the first outer peripheral wall 11 is substantially the same as the inner diameter of the covering portion 4. In addition, in a state before the first honeycomb structure 1 is inserted inside the covering portion 4, the outer diameter of the first outer peripheral wall 11 is preferably slightly larger (for example, 0.2 mm or more) than the inner diameter of the covering portion 4. The outer peripheral surface of the first outer peripheral wall 11 contacts the inner peripheral surface of the covering portion 4 over substantially the entire surface. The outer diameter and inner diameter of the first inner peripheral wall 12 are substantially the same at any position in the Y direction. The outer diameter of the first inner peripheral wall 12 is smaller than the inner diameter of the first outer peripheral wall 11. The first inner peripheral wall 12 is spaced radially inward from the inner peripheral surface of the first outer peripheral wall 11 over the entire circumference in the circumferential direction. The inner diameter of the first outer peripheral wall 11 is, for example, 30 mm to 300 mm. The radial thickness of the first outer peripheral wall 11 is, for example, 0.2 mm to 2.0 mm. The inner diameter of the first inner peripheral wall 12 is, for example, 25 mm to 200 mm. The ratio of the inner diameter of the first inner peripheral wall 12 to the inner diameter of the first outer peripheral wall 11 is, for example, 45% to 90%. The radial thickness of the first inner peripheral wall 12 is, for example, 0.2 mm to 2.0 mm.

[0041] An internal space 100 of the first outer peripheral wall 11 (i.e., a space radially inward from the inner peripheral surface of the first outer peripheral wall 11) is a substantially cylindrical space extending substantially parallel to the Y direction with the central axis J1 as its center. In the following description, within the internal space 100 of the first outer peripheral wall 11, a region between the first outer peripheral wall 11 and the first inner peripheral wall 12 is referred to as an "outer region 101", and a region radially inward from the first inner peripheral wall 12 is referred to as an "inner region 102".

[0042] The outer region 101 is a substantially cylindrical space extending substantially parallel to the Y direction centered on the central axis J1. The outer region 101 is located radially inward from the inner circumferential surface of the first outer circumferential wall 11 and radially outward from the outer circumferential surface of the first inner circumferential wall 12. The inner region 102 is a substantially cylindrical space extending substantially parallel to the Y direction centered on the central axis J1. The inner region 102 is located radially inward from the outer region 101. The inner region 102 is a region surrounded by the outer region 101 over the entire circumferential direction.

[0043] The first partition walls 18 extend approximately parallel to the Y direction in the above-mentioned internal space 100, and divide the internal space 100 to form a plurality of first cells 17. The length in the Y direction of the first partition walls 18 is approximately the same as the total length in the Y direction of the first honeycomb structure 1. The length in the Y direction of the plurality of first cells 17 is also approximately the same as the total length in the Y direction of the first honeycomb structure 1. The shape of the first partition walls 18 in a cross section perpendicular to the Y direction is approximately the same at any position in the Y direction. In the example shown in FIG. 3, the first partition walls 18 in a cross section perpendicular to the Y direction include a plurality of partition wall elements concentrically arranged about the central axis J1, and a plurality of partition wall elements extending radially in a radial direction about the central axis J1.

[0044] The first partition wall 18 includes a first outer partition wall 13 and a first inner partition wall 14. The first outer partition wall 13 is disposed in the outer region 101 and partitions the outer region 101. The first outer partition wall 13 includes a plurality of partition wall elements concentrically arranged about the central axis J1 and a plurality of partition wall elements extending radially in the radial direction about the central axis J1. The radial outer end of the first outer partition wall 13 is intermittently connected to the inner circumferential surface of the first outer peripheral wall 11 over approximately the entire circumference. The radial inner end of the first outer partition wall 13 is intermittently connected to the outer circumferential surface of the first inner peripheral wall 12 over approximately the entire circumference. In the following description, each of the plurality of first cells 17 partitioned by the first outer partition wall 13 in the outer region 101 is also referred to as a "first outer cell 15". The multiple first outer cells 15 are circumferentially arranged along the inner peripheral surface of the first outer peripheral wall 11 and the outer peripheral surface of the first inner peripheral wall 12 .

[0045] The shape of each first outer cell 15 in a cross section perpendicular to the Y direction (hereinafter simply referred to as "cross-sectional shape") is substantially the same at any position in the Y direction. In the example shown in Fig. 3, the cross-sectional shape of the multiple first outer cells 15 is substantially partially annular (i.e., a shape corresponding to a part of a ring) centered on the central axis J1.

[0046] The first outer cells 15 are arranged concentrically about the central axis J1. The first outer cells 15 arranged at the same radial position are arranged at approximately equal angular intervals in the circumferential direction. The thickness of the first outer partition wall 13 located between each two first outer cells 15 adjacent in the circumferential direction and the thickness of the first outer partition wall 13 located between each two first outer cells 15 adjacent in the radial direction are approximately the same, and in the following description, these thicknesses are also simply referred to as the "thickness of the first outer partition wall 13". The thickness of the first outer partition wall 13 is, for example, 0.1 mm to 1.0 mm. The thickness of the first outer partition wall 13 is, for example, thinner than the thickness of the first outer peripheral wall 11 and the thickness of the second outer peripheral wall 21 (described later).

[0047] The cell density of the first outer cells 15 in the outer region 101 is, for example, 25 cpsi (cells / square inch) to 500 cpsi. The cell density is calculated by dividing the total number of the first outer cells 15 in a front view by the area (square inches) of the outer region 101.

[0048] The first inner partition 14 is disposed in the inner region 102 and is a portion that divides the inner region 102. The first inner partition 14 includes a plurality of partition elements that are concentric about the central axis J1 and a plurality of partition elements that extend radially in the radial direction about the central axis J1. A radially outer end of the first inner partition 14 is intermittently connected to the inner circumferential surface of the first inner circumferential wall 12 over substantially the entire circumference. In the following description, each of the plurality of first cells 17 divided by the first inner partition 14 in the inner region 102 is also referred to as a "first inner cell 16."

[0049] The cross-sectional shape of each first inner cell 16 (i.e., the shape in a cross section perpendicular to the Y direction) is substantially the same at any position in the Y direction. In the example shown in Fig. 3, the cross-sectional shape of the multiple first inner cells 16 is substantially sector-shaped or substantially partially annular about the central axis J1. The cross section of each first inner cell 16 (i.e., the cross section perpendicular to the Y direction) is, for example, larger than the cross section of each first outer cell 15.

[0050] The first inner cells 16 are arranged concentrically about the central axis J1. The first inner cells 16 arranged at the same radial position are arranged at approximately equal angular intervals in the circumferential direction. The thickness of the first inner partition wall 14 located between each two first inner cells 16 adjacent in the circumferential direction and the thickness of the first inner partition wall 14 located between each two first inner cells 16 adjacent in the radial direction are approximately the same, and in the following description, these thicknesses are also simply referred to as the "thickness of the first inner partition wall 14". The thickness of the first inner partition wall 14 is, for example, 0.1 mm to 1.0 mm. The thickness of the first inner peripheral wall 12 is, for example, thinner than the thickness of the first outer peripheral wall 11 and the thickness of the second outer peripheral wall 21. In the example shown in FIG. 3, the thickness of the first inner partition wall 14 is approximately the same as the thickness of the first outer partition wall 13. The thickness of the first inner partition wall 14 may be thicker or thinner than the thickness of the first outer partition wall 13.

[0051] The cell density of the first inner cells 16 in the inner region 102 is lower than the cell density of the first outer cells 15. The cell density of the first inner cells 16 is, for example, 12 cpsi to 400 cpsi. The cell density of the first inner cells 16 is, for example, 0% to 60% of the cell density of the first outer cells 15, and is preferably 50% or less. The cell density of the first inner cells 16 is determined by the same method as the cell density of the first outer cells 15. The same applies to other cell densities described below. Specifically, the cell density of the first inner cells 16 is determined by dividing the total number of the multiple first inner cells 16 in a front view by the area (square inches) of the inner region 102.

[0052] The cell density of the first outer cell 15 and the cell density of the first inner cell 16 are not limited to the above ranges and may be changed as appropriate. The cross-sectional shapes of the first outer cell 15 and the first inner cell 16 are not limited to a substantially sector shape or a substantially partial annular shape and may be changed in various ways, such as a substantially square shape, a substantially rectangular shape, a substantially hexagonal shape, or a substantially circular shape. Furthermore, the arrangement of the first outer cell 15 and the arrangement of the first inner cell 16 are not limited to the above examples and may be changed in various ways. For example, in the outer region 101, a plurality of substantially square-shaped first outer cells 15 partitioned by the lattice-shaped first outer partition walls 13 in a front view may be arranged in a matrix shape at substantially equal intervals in the X direction and the Z direction. In this case, the cell density of the first outer cell 15 is calculated by a known method using the cell pitch, which is the center-to-center distance between adjacent first outer cells 15 in a front view. For example, a tool microscope, a microscope, or the like is used to measure a predetermined number of cell pitches, and the arithmetic average of the predetermined number of cell pitches is calculated. And, the arithmetic mean of the cell pitch is p (mm), and the cell density is (25.4 / p) 2 In the inner region 102, a plurality of substantially square first inner cells 16 partitioned by the lattice-like first inner partition walls 14 in a front view may be arranged in a matrix shape at substantially equal intervals in the X direction and the Z direction. In this case, the cell density of the first inner cells 16 is calculated in the same manner as the cell density of the first outer cells 15 described above.

[0053] As shown in FIG. 4, the second honeycomb structure 2 includes a cylindrical second outer peripheral wall 21 and a second partition wall 28. In the example shown in FIG. 4, the second outer peripheral wall 21 is a substantially cylindrical portion extending substantially parallel to the Y direction centered on the central axis J1. The length in the Y direction of the second outer peripheral wall 21 is substantially the same as the total length in the Y direction of the second honeycomb structure 2. The total length in the Y direction of the second honeycomb structure 2 is, for example, 1 mm to 800 mm, and preferably 500 mm or less. In the example shown in FIG. 2, the total length in the Y direction of the second honeycomb structure 2 is substantially the same as the total length in the Y direction of the first honeycomb structure 1. The total length in the Y direction of the second honeycomb structure 2 may be shorter or longer than the total length in the Y direction of the first honeycomb structure 1.

[0054] The outer diameter and inner diameter of the second outer peripheral wall 21 are substantially the same at any position in the Y direction. The outer diameter of the second outer peripheral wall 21 is substantially the same as the inner diameter of the covering portion 4. In addition, before the second honeycomb structure 2 is inserted inside the covering portion 4, the outer diameter of the second outer peripheral wall 21 is preferably slightly larger (for example, 0.2 mm or more) than the inner diameter of the covering portion 4. The outer peripheral surface of the second outer peripheral wall 21 contacts the inner peripheral surface of the covering portion 4 over substantially the entire surface. The inner diameter of the second outer peripheral wall 21 is, for example, 30 mm to 300 mm. The radial thickness of the second outer peripheral wall 21 is, for example, 0.2 mm to 2.0 mm. In the example shown in FIG. 4, the inner diameter and radial thickness of the second outer peripheral wall 21 are substantially the same as the inner diameter and radial thickness of the first outer peripheral wall 11 (see FIG. 3) of the first honeycomb structure 1, respectively. The inner diameter and the radial thickness of the second outer peripheral wall 21 may be different from the inner diameter and the radial thickness of the first outer peripheral wall 11. The internal space 200 of the second outer peripheral wall 21 (i.e., the space radially inward from the inner peripheral surface of the second outer peripheral wall 21) is a substantially cylindrical space extending substantially parallel to the Y direction with the central axis J1 as the center.

[0055] The second partition walls 28 extend approximately parallel to the Y direction in the above-mentioned internal space 200, and divide the internal space 200 to form a plurality of second cells 27. The length in the Y direction of the second partition walls 28 is approximately the same as the overall length in the Y direction of the second honeycomb structure 2. The length in the Y direction of the plurality of second cells 27 is also approximately the same as the overall length in the Y direction of the second honeycomb structure 2. The second partition walls 28 in a cross section perpendicular to the Y direction include a plurality of concentric partition wall elements centered on the central axis J1, and a plurality of partition wall elements extending radially in the radial direction centered on the central axis J1.

[0056] The shape of each second cell 27 in a cross section perpendicular to the Y direction (hereinafter simply referred to as the "cross-sectional shape") is approximately the same at any position in the Y direction. In the example shown in Fig. 4, the cross-sectional shape of the multiple second cells 27 is approximately a sector shape centered on the central axis J1, or approximately a partial ring shape (i.e., a shape corresponding to a part of a ring) centered on the central axis J1.

[0057] The second cells 27 are arranged concentrically about the central axis J1. The second cells 27 arranged at the same radial position are arranged at approximately equal angular intervals in the circumferential direction. The thickness of the second partition wall 28 located between each two second cells 27 adjacent in the circumferential direction is approximately the same as the thickness of the second partition wall 28 located between each two second cells 27 adjacent in the radial direction, and in the following description, these thicknesses are also simply referred to as the "thickness of the second partition wall 28". The thickness of the second partition wall 28 is, for example, 0.1 mm to 1.0 mm. The thickness of the second partition wall 28 may be approximately the same as or different from the thickness of the first outer partition wall 13 and the thickness of the first inner partition wall 14 of the first honeycomb structure 1.

[0058] The cell density of the second cells 27 is, for example, approximately the same as the cell density of the first outer cells 15 and higher than the cell density of the first inner cells 16. The cell density of the second cells 27 is, for example, 25 cpsi to 500 cpsi. The cell density of the second cells 27 may be different from the cell density of the first outer cells 15. Furthermore, the cell density of the second cells 27 may be equal to or lower than the cell density of the first inner cells 16.

[0059] The cell density of the second cells 27 is not limited to the above range and may be changed as appropriate. The cross-sectional shape of the second cells 27 is not limited to a substantially sector shape or a substantially partial ring shape and may be changed in various ways, such as a substantially square shape, a substantially rectangular shape, a substantially hexagonal shape, or a substantially circular shape. The arrangement of the second cells 27 is not limited to the above example and may be changed in various ways. For example, a plurality of substantially square second cells 27 partitioned by lattice-shaped second partition walls 28 in a front view may be arranged in a matrix at substantially equal intervals in the X direction and the Z direction.

[0060] FIG. 5 is a schematic diagram showing a longitudinal section of the heat exchanger member 5 cut along a plane including the central axis J1 and perpendicular to the X direction. In FIG. 5, the parallel oblique lines on the first honeycomb structure 1 and the second honeycomb structure 2 are drawn so that the intervals become narrower as the cell density of the first cells 17 and the second cells 27 increases. That is, in the first honeycomb structure 1, the intervals between the parallel oblique lines in the outer region 101 are narrower than the intervals between the parallel oblique lines in the inner region 102. Moreover, the intervals between the parallel oblique lines on the second honeycomb structure 2 are substantially the same as the intervals between the parallel oblique lines on the outer region 101 of the first honeycomb structure 1. In FIGS. 14, 16, 17, 19 to 30 described later, the relationship between the cell density and the intervals between the parallel oblique lines is the same as that in FIG. 5.

[0061] In the heat exchanger 7, as described above, the first fluid that has flowed into the first honeycomb structure 1 from the (-Y) side exchanges heat with the first partition walls 18, the first outer peripheral wall 11, and the first inner peripheral wall 12 as it passes through the first cells 17 of the first honeycomb structure 1. At this time, in a region near the first outer peripheral wall 11 of the first honeycomb structure 1, heat transferred from the first fluid to the first partition walls 18 transfers relatively quickly to the first outer peripheral wall 11 and the covering portion 4, and then to the second fluid flowing through the second flow passage 70. On the other hand, in a region near the central axis J1 of the first honeycomb structure 1, heat transferred from the first fluid to the first partition walls 18 does not transfer easily to the first outer peripheral wall 11 and the covering portion 4. Therefore, in the first honeycomb structure 1, if the first cells 17 of the same size as in the second honeycomb structure 2 were evenly arranged across the entire cross section (i.e., if the cell density was uniform across the entire cross section), the temperature of the radially inner portion of the first honeycomb structure 1 could become significantly higher than the temperature of the radially outer portion.

[0062] In contrast, in the first honeycomb structure 1 shown in FIG. 3, the cell density of the first inner cells 16 in the inner region 102 including the central axis J1 is lower than the cell density of the first outer cells 15 in the outer region 101. In this way, by making the inner region 102 have a low cell density, the heat transferred from the first fluid flowing through the first inner cells 16 to the first inner partition wall 14 is reduced, and the temperature rise of the first inner partition wall 14 is suppressed. As a result, damage such as melting in the vicinity of the central axis J1 of the first honeycomb structure 1 is suppressed or prevented. In addition, by making the outer region 101 have a high cell density, the heat transfer from the first fluid flowing through the first outer cells 15 to the first outer partition wall 13 is not suppressed, and the heat of the first fluid is efficiently transferred to the first outer peripheral wall 11 and the covering portion 4. As a result, in the first honeycomb structure 1, heat exchange between the first fluid and the second fluid is efficiently performed.

[0063] Furthermore, the first fluid that has passed through the first cells 17 of the first honeycomb structure 1 is cooled by heat exchange with the first honeycomb structure 1. Therefore, in the second honeycomb structure 2, even if the cell density in the vicinity of the central axis J1 is not made lower than the cell density in the vicinity of the second outer peripheral wall 21, an excessive temperature rise does not occur in the vicinity of the central axis J1. For this reason, the cell density of the second cells 27 is made uniform in substantially the entire second honeycomb structure 2, and heat transfer from the first fluid flowing through the second cells 27 to the second partition walls 28 can be efficiently performed. As a result, in the second honeycomb structure 2, heat exchange between the first fluid and the second fluid is efficiently performed.

[0064] As described above, the heat exchange member 5 includes at least the first honeycomb structure 1 and the second honeycomb structure 2. The first honeycomb structure 1 has a cylindrical first peripheral wall 11 and a first partition wall 18. The first partition wall 18 divides the internal space 100 of the first peripheral wall 11 to form a plurality of first cells 17 extending in the axial direction (Y direction in the above example). The second honeycomb structure 2 has a cylindrical second peripheral wall 21 and a second partition wall 28. The second partition wall 28 divides the internal space 200 of the second peripheral wall 21 to form a plurality of second cells 27 extending in the axial direction. Each of the plurality of first cells 17 is a flow path through which a first fluid flows from one side of the axial direction of the first honeycomb structure 1, that is, the upstream side ((-Y) side in the above example) to the other side, that is, the downstream side ((+Y) side in the above example). The second honeycomb structure 2 is disposed in series on the downstream side of the first honeycomb structure 1. The second honeycomb structure 2 is connected to the first honeycomb structure 1 in a state in which the entire amount of the first fluid that has passed through the multiple first cells 17 flows into the second honeycomb structure 2. Each of the multiple second cells 27 is a flow path through which the first fluid that has flowed in from the first honeycomb structure 1 flows.

[0065] The internal space 100 of the first outer peripheral wall 11 includes an outer region 101 and an inner region 102. In the outer region 101, first cells (i.e., first outer cells 15) are arranged circumferentially along the inner peripheral surface of the first outer peripheral wall 11 at a predetermined cell density. The inner region 102 is a region surrounded by the outer region 101 inside the outer region 101. In the inner region 102, the cell density of the first cells (i.e., first inner cells 16) is lower than that of the outer region 101. The heat exchange member 5 exchanges heat between the first fluid flowing through the multiple first cells 17 and the multiple second cells 27 and the second fluid flowing outside the first outer peripheral wall 11 and the second outer peripheral wall 21 and having a lower temperature than the first fluid. This makes it possible to efficiently exchange heat between the first fluid and the second fluid while suppressing the temperature rise of the heat exchange member 5 as described above.

[0066] As described above, it is preferable that the heat exchange member 5 further includes a cylindrical covering portion 4. The covering portion 4 covers the outer peripheral surface of the first outer peripheral wall 11 and the outer peripheral surface of the second outer peripheral wall 21 from the upstream end of the first honeycomb structure 1 to the downstream end of the second honeycomb structure 2. This allows the first honeycomb structure 1 and the second honeycomb structure 2 to be handled as a unit. As a result, the heat exchange member 5 can be easily handled.

[0067] As described above, the cell density of the second cells 27 in the vicinity of the central axis J1 of the second honeycomb structure 2 is preferably higher than the cell density of the first cells (i.e., the first inner cells 16) in the inner region 102 of the first honeycomb structure 1. This allows efficient heat transfer from the first fluid flowing through the second cells 27 to the second honeycomb structure 2 in the vicinity of the central axis J1 of the second honeycomb structure 2 (i.e., the portion axially opposing the inner region 102 of the first honeycomb structure 1). As a result, efficient heat exchange between the first fluid and the second fluid can be achieved in the second honeycomb structure 2.

[0068] As described above, it is preferable that the first honeycomb structure 1 and the second honeycomb structure 2 are mainly composed of ceramics. This can improve the heat resistance, thermal shock resistance, and corrosion resistance of the first honeycomb structure 1 and the second honeycomb structure 2 compared to the first honeycomb structure 1 and the second honeycomb structure 2 mainly composed of other components such as metal.

[0069] The heat exchanger 7 includes the above-mentioned heat exchange member 5 and an outer wall portion 6. The outer wall portion 6 covers the outer peripheral surface of the heat exchange member 5 (in the above example, the outer peripheral surface of the covering portion 4) while being spaced outward from the outer peripheral surface of the heat exchange member 5. The space between the outer peripheral surface of the heat exchange member 5 and the outer wall portion 6 is a flow path (i.e., the second flow path 70) through which the second fluid flows. As described above, the heat exchanger 7 can efficiently exchange heat between the first fluid and the second fluid while suppressing a temperature rise in the heat exchange member 5.

[0070] As described above, the inner diameter of the first outer peripheral wall 11 of the first honeycomb structure 1 (hereinafter, also referred to as the "first outer peripheral wall diameter") is preferably 30 mm to 300 mm. FIG. 6 is a graph showing the relationship between the first outer peripheral wall diameter and the pressure loss of the first fluid when passing through the first honeycomb structure 1. FIG. 7 is a graph showing the relationship between the first outer peripheral wall diameter and the heat recovery amount per unit volume in the first honeycomb structure 1 (i.e., the amount of heat recovered from the first fluid by the first honeycomb structure 1 of unit volume). FIGS. 6 and 7 were obtained by simulation under the conditions of a length of the first honeycomb structure 1 in the Y direction of 20 mm, a cell density of 150 cpsi in the outer region 101, a cell density of 12 cpsi in the inner region 102, a supply temperature of the first fluid (gas) of 400° C., a flow rate of the first fluid of 10 g / sec, a supply temperature of the second fluid (water) of 40° C., and a flow rate of the second fluid of 10 L (liters) / min.

[0071] As shown in Fig. 6, by making the first outer peripheral wall diameter 30 mm or more, the pressure loss can be made equal to or less than the reference pressure loss (e.g., 3 kPa) indicated by the dashed line. Also, as shown in Fig. 7, by making the first outer peripheral wall diameter 300 mm or less, the decrease in the heat recovery amount per unit volume can be suppressed.

[0072] As described above, the inner diameter of the first inner peripheral wall 12 of the first honeycomb structure 1 (hereinafter, also referred to as the "first inner peripheral wall diameter") is preferably 25 mm to 200 mm. FIG. 8 is a graph showing the relationship between the first inner peripheral wall diameter and the maximum temperature of the first honeycomb structure 1 in the inner region 102 when the first fluid passes through (i.e., the maximum temperature of the first inner partition wall 14). FIG. 9 is a graph showing the relationship between the first inner peripheral wall diameter and the pressure loss of the first fluid when passing through the first honeycomb structure 1. FIGS. 8 and 9 were obtained by simulation under the above-mentioned conditions similar to those of FIGS. 6 and 7. As shown in FIG. 8, by setting the first inner peripheral wall diameter to 25 mm or more, the maximum temperature of the first honeycomb structure 1 can be set to a reference temperature (for example, 1350°C) or less indicated by the dashed line. In addition, as shown in FIG. 9, by setting the first inner peripheral wall diameter to 200 mm or less, the pressure loss can be set to a reference pressure loss or less indicated by the dashed line.

[0073] As described above, the ratio of the first inner peripheral wall diameter to the first outer peripheral wall diameter (hereinafter also referred to as the "inner / outer diameter ratio") is preferably 45% to 90%. FIG. 10 is a graph showing the relationship between the inner / outer diameter ratio and the maximum temperature of the first honeycomb structure 1 in the inner region 102 when the first fluid passes through. FIG. 11 is a graph showing the relationship between the inner / outer diameter ratio and the pressure loss of the first fluid when passing through the first honeycomb structure 1. As shown in FIG. 10, by setting the inner / outer diameter ratio to 45% or more, the maximum temperature of the first honeycomb structure 1 can be made equal to or lower than the reference temperature indicated by the dashed line. Also, as shown in FIG. 11, by setting the inner / outer diameter ratio to 90% or less, the pressure loss can be made equal to or lower than the reference pressure loss indicated by the dashed line.

[0074] As described above, the length in the Y direction of the first honeycomb structure 1 is preferably 500 mm or less. FIG. 12 is a graph showing the relationship between the length in the Y direction of the first honeycomb structure 1 and the heat recovery amount per unit volume in the first honeycomb structure 1. FIG. 12 is obtained by simulation under the conditions of a first outer peripheral wall diameter of 85 mm, a first inner peripheral wall diameter of 67 mm, a cell density in the outer region 101 of 262 cpsi, a cell density in the inner region 102 of 12 cpsi, a supply temperature of the first fluid (gas) of 400° C., a flow rate of the first fluid of 10 g / sec, a supply temperature of the second fluid (water) of 40° C., and a flow rate of the second fluid of 10 L (liters) / min. As shown in FIG. 12, by setting the length in the Y direction of the first honeycomb structure 1 to 500 mm or less, the decrease in the heat recovery amount per unit volume can be suppressed.

[0075] As described above, the ratio of the cell density of the first inner cells 16 to the cell density of the first outer cells 15 (hereinafter also referred to as the "inner / outer density ratio") is preferably 50% or less. Fig. 13 is a graph showing the relationship between the inner / outer density ratio and the maximum temperature of the first honeycomb structure 1 in the inner region 102 when the first fluid passes through. Fig. 13 was obtained by simulation under the above-mentioned conditions similar to those in Fig. 12. As shown in Fig. 13, by setting the inner / outer density ratio to 50% or less, the maximum temperature of the first honeycomb structure 1 can be made to be equal to or lower than the reference temperature indicated by the dashed dotted line.

[0076] As described above, the cell density in the outer region 101 of the first honeycomb structure 1 is preferably 25 cpsi or more. This allows the strength of the first honeycomb structure 1 to be relatively large. Also, the surface area of ​​the first outer partition wall 13 that comes into contact with the first fluid in the outer region 101 can be relatively large. As a result, heat can be efficiently recovered from the first fluid in the outer region 101.

[0077] As described above, it is preferable that the thickness of the first outer peripheral wall 11 and the thickness of the first inner peripheral wall 12 are greater than the thickness of the first outer partition wall 13 and the thickness of the first inner partition wall 14. This allows the strength of the first honeycomb structure 1 to be relatively large.

[0078] As described above, the thickness of the first outer partition wall 13 and the thickness of the first inner partition wall 14 are preferably 1.0 mm or less. This makes it possible to suppress an increase in pressure loss due to a decrease in the opening area in the first honeycomb structure 1. In addition, the surface areas of the first outer partition wall 13 and the first inner partition wall 14 that come into contact with the first fluid can be made relatively large. As a result, heat can be efficiently recovered from the first fluid in the outer region 101 and the inner region 102.

[0079] Next, a heat exchange member 5a according to a second embodiment of the present invention will be described. Fig. 14 is a schematic diagram of a longitudinal section of the heat exchange member 5a cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 5. The heat exchange member 5a is housed inside the outer wall portion 6 in place of the heat exchange member 5 shown in Fig. 1, and can be used as a part of the heat exchanger 7. The same applies to other heat exchange members described later.

[0080] 14, in the heat exchange member 5a, instead of the second honeycomb structure 2 of the heat exchange member 5 shown in Fig. 5, a second honeycomb structure 2a and a third honeycomb structure 3a are provided on the (+Y) side of the first honeycomb structure 1. The other structures of the heat exchange member 5a are substantially similar to those of the heat exchange member 5.

[0081] The second honeycomb structure 2a and the third honeycomb structure 3a are each a substantially cylindrical member extending substantially parallel to the Y direction centered on the central axis J1. The second honeycomb structure 2a and the third honeycomb structure 3a each have a structure similar to that of the second honeycomb structure 2 shown in Figs. 4 and 5, except that the length in the Y direction of the second honeycomb structure 2 is shortened. The length in the Y direction of each of the second honeycomb structure 2a and the third honeycomb structure 3a is, for example, about 45% of the length in the Y direction of the second honeycomb structure 2. The length in the Y direction of each of the second honeycomb structure 2a and the third honeycomb structure 3a may be changed in various ways and may be equal to or greater than the length in the Y direction of the second honeycomb structure 2.

[0082] The second honeycomb structure 2a is disposed adjacent to the (+Y) side of the first honeycomb structure 1. The third honeycomb structure 3a is disposed on the (+Y) side of the second honeycomb structure 2a, spaced from the second honeycomb structure 2a on the (+Y) side. In other words, the second honeycomb structures 2a are arranged in series on the downstream side of the first honeycomb structure 1, and the third honeycomb structure 3a is arranged in series on the downstream side of the second honeycomb structure 2a while being spaced from the second honeycomb structure 2a.

[0083] The (+Y) end face of the first honeycomb structure 1 and the (-Y) end face of the second honeycomb structure 2a may be in direct contact with each other, or may be indirectly in contact with each other via a substantially annular cushioning material or the like that is in contact with the outer periphery of both end faces. A substantially circular plate-shaped gap 41 centered on the central axis J1 is provided between the (+Y) end face of the second honeycomb structure 2a and the (-Y) end face of the third honeycomb structure 3a. Note that the gap 41 may be omitted in the heat exchange member 5a, and the (+Y) end face of the second honeycomb structure 2a and the (-Y) end face of the third honeycomb structure 3a may be in direct or indirect contact with each other.

[0084] The covering portion 4 covers the outer peripheral surfaces of the first honeycomb structure 1, the second honeycomb structure 2a, and the third honeycomb structure 3a over the entire length in the Y direction, and connects the first honeycomb structure 1, the second honeycomb structure 2a, and the third honeycomb structure 3a. The inner peripheral surface of the covering portion 4 contacts the outer peripheral surfaces of the first honeycomb structure 1, the second honeycomb structure 2a, and the third honeycomb structure 3a over substantially the entire surfaces.

[0085] The second honeycomb structure 2a includes a plurality of second cells 27 having the same cross-sectional shape, arrangement, cell density, etc. as the plurality of second cells 27 shown in FIG. 4. In the second honeycomb structure 2a, the cell density of the second cells 27 is uniform over the entire cross section, as in the second honeycomb structure 2. As shown in FIG. 15, the third honeycomb structure 3a includes a cylindrical third peripheral wall 31 having the same shape as the second peripheral wall 21 shown in FIG. 4, and a third partition wall 38 having the same shape as the second partition wall 28 shown in FIG. 4. The third partition wall 38 divides the internal space 300 of the third peripheral wall 31 to form a plurality of third cells 37 extending in the Y direction. The plurality of third cells 37 have the same cross-sectional shape, arrangement, cell density, etc. as the plurality of second cells 27 (see FIG. 4) in the second honeycomb structure 2a. In the third honeycomb structure 3a, similarly to the second honeycomb structure 2a, the cell density of the third cells 37 is uniform over the entire cross section.

[0086] In the heat exchange member 5a shown in FIG. 14, the third honeycomb structure 3a is connected to the second honeycomb structure 2a by the covering portion 4 in a state in which the entire amount of the first fluid that has passed through the second cells 27 (see FIG. 4) of the second honeycomb structure 2a flows into the third honeycomb structure 2a. In the example shown in FIG. 14, the first fluid that has passed through the second cells 27 is mixed in the gaps 41 between the second honeycomb structure 2a and the third honeycomb structure 3a, and then flows into the third cells 37 of the third honeycomb structure 3a. The third cells 37 are channels through which the first fluid that has flowed from the second honeycomb structure 2a into the third honeycomb structure 3a flows from the (-Y) side to the (+Y) side.

[0087] In the heat exchange member 5a, similarly to the heat exchange member 5, the heat exchange between the first fluid and the second fluid can be efficiently performed while suppressing a temperature rise of the heat exchange member 5a. Specifically, in the first honeycomb structure 1, the heat exchange between the first fluid and the second fluid can be efficiently performed via the outer region 101 while suppressing a temperature rise of the first inner partition walls 14 (see FIG. 3) in the inner region 102. Also, in the second honeycomb structure 2a, the heat exchange between the first fluid, the temperature of which has been lowered by passing through the first honeycomb structure 1, and the second fluid can be efficiently performed.

[0088] As described above, the heat exchange member 5a further includes the third honeycomb structure 3a. The third honeycomb structure 3a includes a cylindrical third peripheral wall 31 and third partition walls 38 that partition the internal space 300 of the third peripheral wall 31 and form a plurality of third cells 37 extending in the axial direction (Y direction in the above example). The third honeycomb structure 3a is disposed in series on the downstream side of the second honeycomb structure 2a and is connected to the second honeycomb structure 2a in a state in which the entire amount of the first fluid that has passed through the plurality of second cells 27 (see FIG. 4) flows into the third honeycomb structure 3a. Each of the plurality of third cells 37 is a flow path through which the first fluid that has flowed in from the second honeycomb structure 2a flows. This allows the third honeycomb structure 3a to efficiently exchange heat between the first fluid, whose temperature has been reduced by passing through the second honeycomb structure 2a, and the second fluid. The same applies to the case in which the third honeycomb structure 3a is provided in other heat exchange members described later.

[0089] As described above, in the heat exchange member 5a, it is preferable that the gap 41 is provided between the end face on the downstream side (the (+Y) side in the above example) of the second honeycomb structure 2a and the end face on the upstream side (the (-Y) side in the above example) of the third honeycomb structure 3a. In the gap 41, the first fluid having a relatively high temperature that has passed through the second cells 27 located in the vicinity of the central axis J1 in the second honeycomb structure 2a and the first fluid having a relatively low temperature that has passed through the second cells 27 located radially outward are mixed. Therefore, the uniformity of the temperature of the first fluid flowing into each of the multiple third cells 37 is improved. As a result, the efficiency of heat exchange between the first fluid and the second fluid in the third honeycomb structure 3a can be improved.

[0090] Next, a heat exchange member 5b according to a third embodiment of the present invention will be described. FIG. 16 is a schematic diagram of a longitudinal section of the heat exchange member 5b cut along a plane including the central axis J1 and perpendicular to the X direction, similar to FIG. 14. In the heat exchange member 5b, instead of the third honeycomb structure 3a of the heat exchange member 5a shown in FIG. 14, a third honeycomb structure 3b is provided on the (+Y) side of the first honeycomb structure 1 and the second honeycomb structure 2a. The other structures of the heat exchange member 5b are similar to those of the heat exchange member 5a. The third honeycomb structure 3b has a structure similar to that of the third honeycomb structure 3a, except that the cell density of the third cells 37 is lower than that of the third honeycomb structure 3a shown in FIG. 15. In the third honeycomb structure 3b, the cell density of the third cells 37 is uniform throughout the entire cross section, similar to that of the third honeycomb structure 3a.

[0091] In the heat exchange member 5b, the cell density of the third cells 37 in the third honeycomb structure 3b is lower than the cell density of the second cells 27 (see FIG. 4) in the second honeycomb structure 2a. This makes it possible to prevent the first fluid, which has passed through the first honeycomb structure 1 and the second honeycomb structure 2a and has been cooled to a relatively low temperature, from being excessively cooled and condensed when passing through the third honeycomb structure 3b. As a result, it is possible to prevent the third cells 37 from being blocked by liquid generated by the condensation of the first fluid. The same is true in cases where the third honeycomb structure 3b is provided in other heat exchange members described later.

[0092] In the heat exchange member 5b, it is preferable that a gap 41 is provided between the end face on the downstream side (the (+Y) side in the above example) of the second honeycomb structure 2a and the end face on the upstream side (the (-Y) side in the above example) of the third honeycomb structure 3b. This can improve the uniformity of the temperature of the first fluid flowing into each of the third cells 37 as described above, and as a result, the efficiency of heat exchange between the first fluid and the second fluid in the third honeycomb structure 3b can be improved. This is approximately the same when the gap 41 is provided in other heat exchange members described later. Note that the gap 41 may be omitted in the heat exchange member 5b and other heat exchange members described later.

[0093] Next, a heat exchange member 5c according to a fourth embodiment of the present invention will be described. Fig. 17 is a schematic diagram of a longitudinal section of the heat exchange member 5c cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 5. In the heat exchange member 5c, instead of the first honeycomb structure 1 of the heat exchange member 5 shown in Fig. 5, a first honeycomb structure 1c is provided on the (-Y) side of the second honeycomb structure 2. The other structure of the heat exchange member 5c is substantially the same as that of the heat exchange member 5.

[0094] Fig. 18 is a front view of the heat exchange member 5c as viewed from the (-Y) side. As shown in Fig. 17 and Fig. 18, the first honeycomb structure 1c has a similar structure to the first honeycomb structure 1, except that an inner region 102c is provided instead of the inner region 102 of the first honeycomb structure 1 shown in Fig. 3 and Fig. 5. In the first honeycomb structure 1c, the first inner partition wall 14 (see Fig. 3) is not provided radially inside the first inner circumferential wall 12, and the inner region 102c is a substantially cylindrical space extending in the Y direction around the central axis J1.

[0095] The inner region 102c is one first inner cell 16c through which the first fluid supplied to the first honeycomb structure 1c flows. The cross-sectional shape of the first inner cell 16c perpendicular to the Y direction is substantially circular. The cross-sectional area of ​​the first inner cell 16c perpendicular to the Y direction (hereinafter, simply referred to as "cross-sectional area") is larger than the cross-sectional area of ​​each of the first outer cells 15 surrounding the first inner cell 16c on the radial outside (i.e., the outer region 101) of the first inner cell 16c. In the example shown in FIG. 18, the cell density in the inner region 102c is calculated by dividing the cross-sectional area of ​​the first inner cell 16c by A (mm 2 ), then it is 25.4 2 / A.

[0096] As described above, in the heat exchange member 5c, the inner region 102c of the first honeycomb structure 1c is one space constituted by one first cell (i.e., the first inner cell 16c) having a larger cross-sectional area than each of the first cells (i.e., the first outer cell 15) in the outer region 101. This makes it possible to suppress a temperature rise in the vicinity of the central axis J1 of the first honeycomb structure 1c when the first fluid passes through, in a manner similar to that described above. In addition, since the structure of the first honeycomb structure 1c can be simplified, the first honeycomb structure 1c and the heat exchange member 5c can be easily manufactured.

[0097] Fig. 19 is a schematic diagram of a longitudinal section of a heat exchanger member 5d according to a fifth embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 17. In the heat exchanger member 5d, instead of the second honeycomb structure 2 of the heat exchanger member 5c shown in Fig. 17, the second honeycomb structure 2a and the third honeycomb structure 3a shown in Fig. 14 are provided on the (+Y) side of the first honeycomb structure 1c, and a gap 41 is provided between the second honeycomb structure 2a and the third honeycomb structure 3a. The other structure of the heat exchanger member 5d is substantially similar to that of the heat exchanger member 5c.

[0098] Fig. 20 is a schematic diagram of a longitudinal section of a heat exchanger member 5e according to a sixth embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 19. In the heat exchanger member 5e, the third honeycomb structure 3b shown in Fig. 16 is provided on the (+Y) side of the first honeycomb structure 1c and the second honeycomb structure 2a, instead of the third honeycomb structure 3a of the heat exchanger member 5d shown in Fig. 19. The other structure of the heat exchanger member 5e is substantially similar to that of the heat exchanger member 5d.

[0099] Next, a heat exchange member 5f according to a seventh embodiment of the present invention will be described. Fig. 21 is a schematic diagram of a longitudinal section of the heat exchange member 5f cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 5. In the heat exchange member 5f, instead of the first honeycomb structure 1 of the heat exchange member 5 shown in Fig. 5, a first honeycomb structure 1f is provided on the (-Y) side of the second honeycomb structure 2. The other structure of the heat exchange member 5f is substantially the same as that of the heat exchange member 5.

[0100] The first honeycomb structure 1f has a structure substantially similar to that of the first honeycomb structure 1, except that an inner region 102f is provided instead of the inner region 102 of the first honeycomb structure 1 shown in FIG. 5. In the first honeycomb structure 1f, the inner region 102f includes a front inner region 103f and a rear inner region 104f. The rear inner region 104f is arranged in series on the (+Y) side of the front inner region 103f. The front inner region 103f and the rear inner region 104f are substantially cylindrical spaces extending in the Y direction with the center at the central axis J1. The cross-sectional area of ​​the front inner region 103f (i.e., the area of ​​a cross section perpendicular to the Y direction) is larger than the cross-sectional area of ​​the rear inner region 104f.

[0101] The front inner region 103f extends in the (+Y) direction from the end face on the (-Y) side of the first honeycomb structure 1f. The rear inner region 104f extends in the (+Y) direction from the end of the (+Y) side of the front inner region 103f, and reaches the end face on the (+Y) side of the first honeycomb structure 1f. In other words, the front inner region 103f is located in the upstream part of the first honeycomb structure 1f, and the rear inner region 104f is located in the downstream part of the first honeycomb structure 1f. In the inner region 102f (i.e., the front inner region 103f and the rear inner region 104f), the first inner partition wall 14 is provided in a manner substantially similar to the inner region 102 shown in FIG. 3, and a plurality of first inner cells 16 (see FIG. 3) are formed.

[0102] In the first honeycomb structure 1f, the cell density of the first inner cells 16 in the inner region 102f is lower than the cell density of the first outer cells 15 (see FIG. 3) in the outer region 101f, which is a region radially outside the inner region 102f. Therefore, as described above, it is possible to efficiently exchange heat between the first fluid and the second fluid while suppressing a temperature rise in the first inner partition walls 14 (see FIG. 3) in the inner region 102f when the first fluid passes through.

[0103] Furthermore, the temperature of the first fluid that has flowed into the inner region 102f from the end of the (-Y) side of the first honeycomb structure 1f is reduced by passing through the first inner cells 16 (see FIG. 3) of the front inner region 103f. Therefore, even if the cross-sectional area of ​​the rear inner region 104f, which has a lower cell density than the surrounding outer region 101f, is made smaller than that of the front inner region 103f in the (+Y) side portion of the first honeycomb structure 1f, the temperature rise of the first inner partition wall 14 (see FIG. 3) can be suitably suppressed. Furthermore, by making the cross-sectional area of ​​the rear inner region 104f smaller, the cross-sectional area of ​​the outer region 101f with high cell density located around (i.e., radially outside) the rear inner region 104f can be made larger, so that heat can be efficiently recovered from the first fluid flowing through the first outer cells 15 (see FIG. 3) of the outer region 101f.

[0104] In this way, in the heat exchange member 5f, the cross-sectional area of ​​the inner region 102f (i.e., the cross-sectional area of ​​the front inner region 103f) at the upstream side (in the above example, the (-Y) side) of the first honeycomb structure 1f is made larger than the cross-sectional area of ​​the inner region 102f (i.e., the cross-sectional area of ​​the rear inner region 104f) at the downstream side (in the above example, the (+Y) side) of the first honeycomb structure 1f, so that heat exchange between the first and second fluids can be performed more efficiently in the first honeycomb structure 1f while suppressing temperature rise.

[0105] Fig. 22 is a schematic diagram of a longitudinal section of a heat exchanger member 5g according to an eighth embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 21. In the heat exchanger member 5g, instead of the second honeycomb structure 2 of the heat exchanger member 5f shown in Fig. 21, the second honeycomb structure 2a and the third honeycomb structure 3a shown in Fig. 14 are provided on the (+Y) side of the first honeycomb structure 1f, and a gap 41 is provided between the second honeycomb structure 2a and the third honeycomb structure 3a. The other structure of the heat exchanger member 5g is substantially the same as that of the heat exchanger member 5f.

[0106] Fig. 23 is a schematic diagram of a longitudinal section of a heat exchanger member 5h according to a ninth embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 22. In the heat exchanger member 5h, the third honeycomb structure 3b shown in Fig. 16 is provided on the (+Y) side of the first honeycomb structure 1f and the second honeycomb structure 2a, instead of the third honeycomb structure 3a of the heat exchanger member 5g shown in Fig. 22. The other structures of the heat exchanger member 5h are substantially similar to those of the heat exchanger member 5g.

[0107] Fig. 24 is a schematic diagram of a longitudinal section of a heat exchanger 5i according to a tenth embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 21. In the heat exchanger 5i, instead of the first honeycomb structure 1f of the heat exchanger 5f shown in Fig. 21, a first honeycomb structure 1i is provided on the (-Y) side of the second honeycomb structure 2. In the first honeycomb structure 1i, one space is provided as the inner region 102i, in which the first inner partition wall 14 (see Fig. 3) is omitted from the inner region 102f of the first honeycomb structure 1f. The other structure of the heat exchanger 5i is substantially similar to that of the heat exchanger 5f.

[0108] The inner region 102i is a space constituted by one first cell (i.e., the first inner cell 16i) having a larger cross-sectional area than each of the first outer cells 15 (see FIG. 3) of the outer region 101f. This makes it possible to suppress a temperature rise in the vicinity of the central axis J1 of the first honeycomb structure 1i when the first fluid passes through, in a manner similar to that described above. In addition, since the structure of the first honeycomb structure 1i can be simplified, it is possible to facilitate the manufacture of the first honeycomb structure 1i and the heat exchange member 5i.

[0109] Fig. 25 is a schematic diagram of a longitudinal section of a heat exchanger member 5j according to an eleventh embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, in a manner similar to Fig. 24. In the heat exchanger member 5j, instead of the second honeycomb structure 2 of the heat exchanger member 5i shown in Fig. 24, the second honeycomb structure 2a and the third honeycomb structure 3a shown in Fig. 14 are provided on the (+Y) side of the first honeycomb structure 1i, and a gap 41 is provided between the second honeycomb structure 2a and the third honeycomb structure 3a. The other structure of the heat exchanger member 5j is substantially the same as that of the heat exchanger member 5i.

[0110] Fig. 26 is a schematic diagram of a longitudinal section of a heat exchanger 5k according to a twelfth embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 25. In the heat exchanger 5k, the third honeycomb structure 3b shown in Fig. 16 is provided on the (+Y) side of the first honeycomb structure 1i and the second honeycomb structure 2a, instead of the third honeycomb structure 3a of the heat exchanger 5j shown in Fig. 25. The other structure of the heat exchanger 5k is substantially similar to that of the heat exchanger 5j.

[0111] Fig. 27 is a schematic diagram of a longitudinal section of a heat exchanger 5m according to a thirteenth embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 21. In the heat exchanger 5m, instead of the first honeycomb structure 1f of the heat exchanger 5f shown in Fig. 21, a first honeycomb structure 1m is provided on the (-Y) side of the second honeycomb structure 2. The other structure of the heat exchanger 5m is substantially similar to that of the heat exchanger 5f.

[0112] The first honeycomb structure 1m has a structure substantially similar to that of the first honeycomb structure 1f, except that the inner region 102m is provided instead of the inner region 102f of the first honeycomb structure 1f shown in FIG. 21. In the first honeycomb structure 1m, the inner region 102m is a substantially conical space extending in the Y direction centered on the central axis J1. The cross-sectional area of ​​the inner region 102m gradually decreases from the (-Y) side toward the (+Y) side. The inner region 102m extends from the end face on the (-Y) side of the first honeycomb structure 1m in the (+Y) direction, and reaches the end face on the (+Y) side of the first honeycomb structure 1m. In other words, the inner region 102m is provided over the entire length of the first honeycomb structure 1m in the Y direction. The inner region 102m is provided with a first inner partition 14 in a manner similar to that of the inner region 102 shown in Fig. 3, and a plurality of first inner cells 16 (see Fig. 3) are formed. In addition, the outer region 101m located around (i.e., radially outside) the inner region 102m is provided with a plurality of first outer cells 15 (see Fig. 3).

[0113] In the heat exchange member 5m, the cross-sectional area of ​​the inner region 102m at the upstream side ((-Y) side in the above example) of the first honeycomb structure 1m is larger than the cross-sectional area of ​​the inner region 102m at the downstream side ((+Y) side in the above example) of the first honeycomb structure 1m, substantially similar to the first honeycomb structure 1f shown in Fig. 21. This allows the first honeycomb structure 1m to more efficiently exchange heat between the first and second fluids while suppressing a temperature rise, substantially similar to the first honeycomb structure 1f.

[0114] In the heat exchange member 5m, the second honeycomb structure 2 may be replaced by a second honeycomb structure 2a and a third honeycomb structure 3a shown in Fig. 14. Alternatively, the second honeycomb structure 2 may be replaced by a second honeycomb structure 2a and a third honeycomb structure 3b shown in Fig. 16. In either case, the voids 41 may or may not be provided. The same applies to the heat exchange members 5n to 5p described later.

[0115] Fig. 28 is a schematic diagram of a longitudinal section of a heat exchanger 5n according to a fourteenth embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 27. In the heat exchanger 5n, instead of the first honeycomb structure 1m of the heat exchanger 5m shown in Fig. 27, a first honeycomb structure 1n is provided on the (-Y) side of a second honeycomb structure 2. In the first honeycomb structure 1n, one space is provided as an inner region 102n by omitting the first inner partition wall 14 (see Fig. 3) from the inner region 102m of the first honeycomb structure 1m. The other structure of the heat exchanger 5n is substantially similar to that of the heat exchanger 5m.

[0116] The inner region 102n is a space constituted by one first cell (i.e., the first inner cell 16n) having a larger cross-sectional area at the end portion on the (-Y) side of the first honeycomb structure 1n than each of the first outer cells 15 (see FIG. 3) of the outer region 101m. This makes it possible to suppress a temperature rise in the vicinity of the central axis J1 of the first honeycomb structure 1n when the first fluid passes through, in a manner similar to that described above. In addition, since the structure of the first honeycomb structure 1n can be simplified, the first honeycomb structure 1n and the heat exchange member 5n can be easily manufactured.

[0117] Fig. 29 is a schematic longitudinal cross-sectional view of a heat exchanger 5o according to a fifteenth embodiment of the present invention, taken along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 27. In the heat exchanger 5o, instead of the first honeycomb structure 1m of the heat exchanger 5m shown in Fig. 27, a first honeycomb structure 1o is provided on the (-Y) side of a second honeycomb structure 2. The other structures of the heat exchanger 5o are substantially similar to those of the heat exchanger 5m.

[0118] The first honeycomb structure 1o has a structure substantially similar to that of the first honeycomb structure 1m, except that the inner region 102o is provided instead of the inner region 102m of the first honeycomb structure 1m shown in FIG. 27. In the first honeycomb structure 1o, the inner region 102o has a shape in which a substantially hemispherical space is connected to the (+Y) end of a substantially cylindrical space extending in the Y direction centered on the central axis J1. The cross-sectional area of ​​the (+Y) end (i.e., the substantially hemispherical portion) of the inner region 102o gradually decreases from the (-Y) side toward the (+Y) side. The inner region 102o extends from the (-Y) side end face of the first honeycomb structure 1o in the (+Y) direction, and reaches the (+Y) side end face of the first honeycomb structure 1o. In other words, the inner region 102o is provided over the entire length of the first honeycomb structure 1o in the Y direction. The inner region 102o is provided with a first inner partition 14 in a manner similar to that of the inner region 102 shown in Fig. 3, and a plurality of first inner cells 16 (see Fig. 3) are formed. In addition, the outer region 101o located around (i.e., radially outside) the inner region 102o is provided with a plurality of first outer cells 15 (see Fig. 3).

[0119] In the heat exchange member 5o, the cross-sectional area of ​​the inner region 102o in the upstream side (the (-Y) side in the above example) of the first honeycomb structure 1o is larger than the cross-sectional area of ​​the inner region 102o in the downstream side (the (+Y) side in the above example) of the first honeycomb structure 1o, substantially similar to the first honeycomb structure 1m shown in Fig. 27. This allows the first honeycomb structure 1o to more efficiently exchange heat between the first and second fluids while suppressing a temperature rise, substantially similar to the first honeycomb structure 1m.

[0120] Fig. 30 is a schematic diagram of a longitudinal section of a heat exchanger 5p according to a sixteenth embodiment of the present invention, cut along a plane including the central axis J1 and perpendicular to the X direction, similar to Fig. 29. In the heat exchanger 5p, instead of the first honeycomb structure 1o of the heat exchanger 5o shown in Fig. 29, a first honeycomb structure 1p is provided on the (-Y) side of the second honeycomb structure 2. In the first honeycomb structure 1p, one space is provided as an inner region 102p by omitting the first inner partition wall 14 (see Fig. 3) from the inner region 102o of the first honeycomb structure 1o. The other structure of the heat exchanger 5p is substantially similar to that of the heat exchanger 5o.

[0121] The inner region 102p is a space constituted by one first cell (i.e., the first inner cell 16p) having a larger cross-sectional area at the end portion on the (-Y) side of the first honeycomb structure 1p than each of the first outer cells 15 (see FIG. 3) in the outer region 101o. This makes it possible to suppress a temperature rise in the vicinity of the central axis J1 of the first honeycomb structure 1p when the first fluid passes through, in a manner similar to that described above. In addition, since the structure of the first honeycomb structure 1p can be simplified, the first honeycomb structure 1p and the heat exchange member 5p can be easily manufactured.

[0122] The above-mentioned heat exchange members 5, 5a to 5k, 5m to 5p and heat exchanger 7 can be modified in various ways.

[0123] For example, the heat exchanger 7 does not necessarily have to be used for recovering heat from vehicle exhaust gases, but may be used for recovering heat from a variety of fluids.

[0124] In the first honeycomb structure 1f shown in Fig. 21, the shape of the inner region 102f may be appropriately changed as long as the cross-sectional area of ​​the inner region 102f at the (-Y) side is larger than the cross-sectional area of ​​the inner region 102f at the (+Y) side. For example, in the example shown in Fig. 21, the vertical cross section of the inner region 102f is reduced in a step-like manner in one step at the center in the Y direction of the first honeycomb structure 1f (i.e., it is rapidly reduced at approximately one point in the Y direction), but this is not limited thereto, and for example, the vertical cross section of the inner region 102f may be reduced in a step-like manner in multiple steps from the (-Y) side to the (+Y) side. Similarly, in the first honeycomb structures 1i, 1m to 1p, the shape of the inner region may be appropriately changed.

[0125] 2, the covering portion 4 does not necessarily have to be provided over the entire length of the first honeycomb structure 1 and the second honeycomb structure 2, and may be connected to the first honeycomb structure 1 and the second honeycomb structure 2, for example, in a state where the covering portion 4 covers almost the entire periphery of the outer circumferential surfaces of the first honeycomb structure 1 and the second honeycomb structure 2 only in the vicinity of the connection between the first honeycomb structure 1 and the second honeycomb structure 2. The same applies to the connection between the second honeycomb structure 2a and the third honeycomb structure 3a shown in FIG.

[0126] 14, in addition to the second honeycomb structure 2a and the third honeycomb structure 3a, one or more honeycomb structures may be provided in series with the first honeycomb structure 1, etc., on the (+Y) side of the first honeycomb structure 1. The same applies to the heat exchange member 5b, etc. shown in FIG.

[0127] In the heat exchange member 5 shown in Fig. 5, the central axis J1 passing through the first honeycomb structure 1 and the second honeycomb structure 2 does not necessarily have to be linear, and may be bent, for example, between the first honeycomb structure 1 and the second honeycomb structure 2. In this case, the central axis J1 of the first honeycomb structure 1 and the central axis J1 of the second honeycomb structure 2 face in different directions. In addition, in this case, the axial direction is a direction parallel to the central axis J1 at each position on the central axis J1. The same applies to other heat exchange members.

[0128] In the heat exchange member 5, the first honeycomb structure 1 and the second honeycomb structure 2 may be an integrally formed member. In the heat exchange member 5a shown in Fig. 14, the first honeycomb structure 1 and the second honeycomb structure 2a may be an integrally formed member, or the second honeycomb structure 2a and the third honeycomb structure 3a may be an integrally formed member. Alternatively, the first honeycomb structure 1, the second honeycomb structure 2a, and the third honeycomb structure 3a may be an integrally formed member. The same applies to other heat exchange members.

[0129] In the heat exchange member 5c shown in Fig. 17 and Fig. 18, a cylindrical member 19c may be provided on the radially inner side of the first inner peripheral wall 12 of the first honeycomb structure 1c, as shown in Fig. 31. The cylindrical member 19c is a substantially cylindrical member centered on the central axis J1. The cylindrical member 19c contacts the inner peripheral surface of the first inner peripheral wall 12 (see Fig. 18) from the radially inner side. In other words, the cylindrical member 19c is disposed between the inner region 102c (i.e., the first inner cell 16c) and the outer region 101 of the first honeycomb structure 1c. The (+Y) side edge of the cylindrical member 19c is located at substantially the same position as the (+Y) side end face of the first honeycomb structure 1c in the Y direction. The (-Y) side end of the cylindrical member 19c protrudes toward the (-Y) side beyond the (-Y) side end face of the first honeycomb structure 1c. The (-Y) side edge of the cylindrical member 19c is located at approximately the same position as the (-Y) side edge of the covering portion 4 in the Y direction. The cylindrical member 19c is formed of a metal such as stainless steel. In the heat exchange member 5c shown in FIG. 31, the cylindrical member 19c is provided, so that the strength of the first honeycomb structure 1c can be increased. In addition, the heat of the first fluid passing through the first inner cell 16c can be suitably transferred to the outer region 101 through the cylindrical member 19c. Similarly, in the heat exchange members 5d and 5e, the cylindrical member 19c may be provided between the inner region 102c and the outer region 101 of the first honeycomb structure 1c. The same is true for the heat exchange members 5j, 5k, 5n, and 5p.

[0130] The first outer peripheral wall 11 and the first inner peripheral wall 12 of the first honeycomb structure 1, the second outer peripheral wall 21 of the second honeycomb structure 2, and the third outer peripheral wall 31 of the third honeycomb structure 3a do not necessarily have to be substantially cylindrical as long as they are cylindrical, and may be variously modified. For example, the cross-sectional shape perpendicular to the Y direction of the first outer peripheral wall 11 and the first inner peripheral wall 12 of the first honeycomb structure 1, the second outer peripheral wall 21 of the second honeycomb structure 2, and the third outer peripheral wall 31 of the third honeycomb structure 3a may each be a polygon such as a rectangle or a hexagon, or may be an ellipse. The same applies to the other honeycomb structures.

[0131] The first honeycomb structure 1, the second honeycomb structures 2, 2a, and the third honeycomb structures 3a, 3b may or may not contain ceramics as a main component, as in the other first honeycomb structures.

[0132] The heat exchange member 5 does not necessarily have to be used in the heat exchanger 7, but may be used in other devices. The same applies to other heat exchange members.

[0133] The configurations in the above-described embodiment and each of the modified examples may be combined as appropriate as long as they are not mutually inconsistent. [Industrial Applicability]

[0134] The present invention can be used, for example, for heat recovery from exhaust gases of automobiles. [Explanation of symbols]

[0135] 1, 1c, 1f, 1i, 1m to 1p First honeycomb structure 2, 2a Second honeycomb structure 3a, 3b Third honeycomb structure 4 Covering part 5,5a~5k,5m~5p Heat exchanger components 6 Exterior wall 7 Heat exchanger 11 First outer wall 17 Cell 1 18 1st bulkhead 21 Second outer peripheral wall 27 Cell 2 28 Second bulkhead 31 Third outer wall 37 Cell 3 38 Third bulkhead 41 void 70 Second Flow Stream 100 Interior Space 101,101f,101m,101o outer area 102,102c,102f,102i,102m~102p inner area 200 Interior space 300 Internal space J1 Central axis

Claims

1. A heat exchange member, A first honeycomb structure having a cylindrical first outer peripheral wall and first partition walls that divide an internal space of the first outer peripheral wall and form a plurality of first cells extending in an axial direction; A second honeycomb structure having a cylindrical second outer peripheral wall and second partition walls that partition an internal space of the second outer peripheral wall to form a plurality of second cells extending in an axial direction; At least Each of the plurality of first cells is a flow path through which a first fluid flows from an upstream side, which is one side, in the axial direction of the first honeycomb structure, to a downstream side, which is the other side, the second honeycomb structure is disposed in series on the downstream side of the first honeycomb structure and is connected to the first honeycomb structure in a state in which the entire amount of the first fluid that has passed through the plurality of first cells flows into the second honeycomb structure; Each of the second cells is a flow path through which the first fluid flows from the first honeycomb structure, The internal space of the first outer peripheral wall is an outer region in which first cells are circumferentially arranged at a predetermined cell density along an inner peripheral surface of the first outer peripheral wall; an inner region that is inside the outer region and surrounded by the outer region, the inner region having a lower cell density of first cells than the outer region; Equipped with A heat exchange member that exchanges heat between the first fluid flowing through the plurality of first cells and the plurality of second cells and a second fluid that is at a lower temperature than the first fluid flowing outside the first outer peripheral wall and the second outer peripheral wall.

2. The heat exchange element according to claim 1, A heat exchange element further comprising a cylindrical covering portion covering the outer peripheral surface of the first outer peripheral wall and the outer peripheral surface of the second outer peripheral wall from the upstream end of the first honeycomb structure to the downstream end of the second honeycomb structure.

3. The heat exchange element according to claim 1, The heat exchange element, wherein the inner region is a space defined by one first cell having a cross-sectional area larger than each of the first cells in the outer region.

4. The heat exchange element according to claim 1, A heat exchange member, wherein a cross-sectional area of ​​the inner region at the upstream side portion of the first honeycomb structure is larger than a cross-sectional area of ​​the inner region at the downstream side portion of the first honeycomb structure.

5. The heat exchange element according to claim 1, A heat exchange member, wherein a cell density of second cells in the vicinity of a central axis of the second honeycomb structure is higher than a cell density of first cells in the inner region of the first honeycomb structure.

6. The heat exchange element according to claim 1, A third honeycomb structure having a cylindrical third outer peripheral wall and third partition walls that divide an internal space of the third outer peripheral wall and form a plurality of third cells extending in an axial direction, the third honeycomb structure is disposed in series on the downstream side of the second honeycomb structure and is connected to the second honeycomb structure in a state in which the entire amount of the first fluid that has passed through the plurality of second cells flows into the third honeycomb structure; Each of the third cells is a heat exchange member that is a flow path through which the first fluid flows from the second honeycomb structure.

7. The heat exchange element according to claim 6, A heat exchange member, wherein a cell density of third cells in the third honeycomb structure is lower than a cell density of second cells in the second honeycomb structure.

8. The heat exchange element according to claim 6, A heat exchange member comprising: a gap provided between the downstream end face of the second honeycomb structure and the upstream end face of the third honeycomb structure.

9. The heat exchange element according to claim 1, The first honeycomb structure and the second honeycomb structure are heat exchange members whose main component is ceramics.

10. 1. A heat exchanger comprising: A heat exchange member according to any one of claims 1 to 9; an outer wall portion covering the outer peripheral surface of the heat exchange member in a state spaced outward from the outer peripheral surface of the heat exchange member; Equipped with A heat exchanger, wherein a space between the outer peripheral surface of the heat exchange member and the outer wall portion is a flow path through which the second fluid flows.

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