EP4617603A1

EP4617603A1 - Heat exchanger

Info

Publication number: EP4617603A1
Application number: EP25161709.8A
Authority: EP
Inventors: Shinnosuke Iwasaki; Tatsuya AKAHANI
Original assignee: NGK Insulators Ltd
Current assignee: NGK Insulators Ltd
Priority date: 2024-03-15
Filing date: 2025-03-04
Publication date: 2025-09-17
Also published as: JP2025141615A; CN120651026A; US20250290699A1

Abstract

A heat exchanger includes a first honeycomb structure 10, a first cylindrical member 20, and a second honeycomb structure 30. The first honeycomb structure 10 has an outer peripheral wall 11 and partition walls 13 that are disposed on an inner side of the outer peripheral wall 11 and define a plurality of cells 12 to form flow paths for a first fluid. The first outer cylinder 20 is fitted into the outer peripheral wall 11 of the first honeycomb structure 10. The second honeycomb structure 30 has an outer peripheral wall 31, an inner peripheral wall 35, and partition walls 33 that are disposed between the outer peripheral wall 31 and the inner peripheral wall 35 and that define a plurality of cells 32 which serve as flow paths for the second fluid, and the inner peripheral wall 35 is fitted into the first cylindrical member 20.

Description

FIELD OF THE INVENTION

The present invention relates to a heat exchanger.

BACKGROUND OF THE INVENTION

Heat exchangers are used in various systems to preheat fuel air and water vapor using heat sources such as exhaust gas. For example, there are heat exchangers that preheat combustion air using exhaust gases from boilers used in thermal power plants as a heat source, and heat exchangers that generate and preheat water vapor using exhaust gases from fuel cells as a heat source. Systems that use such heat exchangers are known to have effects of reducing used energy because they reuse energy that would otherwise be waste heat, such as exhaust gases.
As a heat exchanger used in the above techniques, Patent Literature 1 proposes a heat exchanger including: a heat collector formed as a honeycomb structure having a plurality of cells which pass through from one end to the other end to form flow paths for a first fluid, and partition walls made mainly of ceramics, which define the plurality of cells; a heat transfer portion having an outer peripheral wall made mainly of ceramics, the outer peripheral wall being provided around an outer periphery of the heat collector, wherein the heat transfer portion intervenes to transfer the heat between the first fluid and a second fluid while separating the first fluid and the second fluid flowing around the outer periphery side of the heat collector by the outer peripheral wall; and an intermediate wall surrounding the cells in the central portion of the plurality of cells to divide the cells into the cells in the central portion and the cells in the remaining outer peripheral portion, the intermediate wall being made mainly of ceramics having a larger thickness that that of the partition wall.
As a heat exchanger particularly suitable for heat exchange between gases, Patent Literature 2 proposes a heat exchanger comprising a ceramic structure including: a three-dimensional mesh structure portion having partition walls and/or communicating pores that define 2 x 2 or more rows of cells forming first fluid communication portions, which are first flow paths; via an intermediate wall around the periphery of the partition walls and/or the communication pores, partition walls defining a plurality of cells forming second fluid communication portions, which are flow paths for a second fluid, and/or the three-dimensional mesh structure portion; and an outer peripheral wall around its periphery, wherein at least one or more pairs of inflow portions for the second fluid to flow into the second fluid communication portions from outside and discharge portions for the second fluid to flow into the second fluid communication portions to discharge it to the outside are provided at a part of the outer peripheral wall.

PRIOR ART

Patent Literatures

[Patent Literature 1] Japanese Patent Application Publication No. 2012-189229 A
[Patent Literature 2] Japanese Patent Application Publication No. 2015-042934 A

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

Both of the heat exchangers in Patent Literatures 1 and 2 have the intermediate wall separating the flow path for the first fluid from the flow path for the second fluid.
However, since the intermediate wall is made of a material containing ceramics as a main component, there is a concern that each fluid flows into a different flow path through pores in the intermediate wall, causing the fluids to be mixed with each other.
The present invention has been made to solve the above problems. An object of the present invention is to provide a heat exchanger which can control the mixing of the first fluid with the second fluid.

Means for Solving the Problem

The present inventors have found that the above problems can be solved by disposing a cylindrical member between two types of honeycomb structures, and have completed the present invention. In other words, the invention is exemplified as follows:

[1] A heat exchanger, comprising:
- a first honeycomb structure having an outer peripheral wall and partition walls disposed on an inner side of the outer peripheral wall, the partition walls defining a plurality of cells to form flow paths for a first fluid;
- a first cylindrical member fitted into the outer peripheral wall of the first honeycomb structure; and
- a second honeycomb structure having an outer peripheral wall, an inner peripheral wall, and partition walls disposed between the outer peripheral wall and the inner peripheral wall, the partition walls defining a plurality of cells to form flow paths for a second fluid, wherein the inner peripheral wall is fitted into the first cylindrical member.
[2] The heat exchanger according to [1], further comprising a heat conductive material disposed between the first honeycomb structure and the first cylindrical member and/or between the second honeycomb structure and the first cylindrical member.
[3] The heat exchanger according to [1] or [2], wherein both end faces of the second honeycomb structure are located on inner sides of both end faces of the first honeycomb structure in an axial direction of the first honeycomb structure and the second honeycomb structure.
[4] The heat exchanger according to any one of [1] to [3], wherein both end portions of the first cylindrical member are located on outer sides of both end faces of the first honeycomb structure and the second honeycomb structure in an axial direction of the first honeycomb structure and the second honeycomb structure.
[5] The heat exchanger according to any one of [1] to [4], wherein, in a cross section orthogonal to an extending direction of the cells of the first honeycomb structure and the second honeycomb structure, the partition walls have first partition walls each extending in a circumferential direction and second partition walls each extending in a radial direction.
[6] The heat exchanger according to any one of [1] to [5], wherein the second honeycomb structure is divided into multiple portions in a cross section orthogonal to an extending direction of the cells of the second honeycomb structure.
[7] The heat exchanger according to any one of [1] to [6], wherein the first honeycomb structure and/or the second honeycomb structure contain ceramics as a main component.
[8] The heat exchanger according to [7], wherein the ceramics contains silicon carbide as a main component.
[9] The heat exchanger according to any one of [1] to [8], wherein the first cylindrical member is made of a metal material.
[10] The heat exchanger according to any one of [1] to [9], wherein at least one end portion of the first cylindrical member has a decreased or increased diameter.
[11] The heat exchanger according to any one of [1] to [10], further comprising a second cylindrical member fitted into at least a part of the outer peripheral wall of the second honeycomb structure, wherein the second cylindrical member has an inflow port and a discharge port for the second fluid.
[12] The heat exchanger according to [11], further comprising a heat insulating material disposed between the second honeycomb structure and the second cylindrical member.
[13] The heat exchanger according to any one of [1] to [12], wherein the flow direction of the first fluid and the flow direction of the second fluid are opposite to each other.
[14] The heat exchanger according to any one of [1] to [13], wherein the first honeycomb structure further comprises an inner peripheral wall that forms a hollow region therein, the hollow region serving as a flow path for a third fluid.
[15] The heat exchanger according to [14], further comprising a third cylindrical member fitted into at least a part of the inner peripheral wall of the first honeycomb structure, wherein the third cylindrical member has an inflow port and a discharge port for the third fluid.

Effects of the Invention

According to the present invention, it is possible to provide a heat exchanger that can suppress mixing of the first fluid with the second fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional view of a heat exchanger according to Embodiment 1 of the present invention, which is parallel to an extending direction of cells;
FIG. 1B is a cross-sectional view of the heat exchanger of FIG. 1A taken along the line a-a';
FIG. 2A is a cross-sectional view of another heat exchanger according to Embodiment 1 of the present invention, which is orthogonal to an extending direction of cells;
FIG. 2B is a cross-sectional view of anther heat exchanger according to Embodiment 1 of the present invention, which is orthogonal to an extending direction of cells;
FIG. 3A is a cross-sectional view of another heat exchanger according to Embodiment 1 of the present invention, which is parallel to an extending direction of cells;
FIG. 3B is a cross-sectional view of another heat exchanger according to Embodiment 1 of the present invention, which is parallel to an extending direction of cells;
FIG. 4A is a cross-sectional view of a heat exchanger according to Embodiment 2 of the present invention, which is parallel to an extending direction of cells;
FIG. 4B is a cross-sectional view of the heat exchanger of FIG. 4A taken along the line b-b';
FIG. 5 is a cross-sectional view of a heat exchanger according to Embodiment 3 of the present invention, which is parallel to an extending direction of cells;
FIG. 6 is a cross-sectional view of another heat exchanger according to Embodiment 3 of the present invention, which is parallel to an extending direction of cells;
FIG. 7A is a cross-sectional view of a heat exchanger according to Embodiment 4 of the present invention, which is parallel to an extending direction of cells;
FIG. 7B is a cross-sectional view of the heat exchanger of FIG. 7A taken along the line c-c';
FIG. 8A is a cross-sectional view of another heat exchanger according to Embodiment 4 of the present invention, which is parallel to an extending direction of cells; and
FIG. 8B is a cross-sectional view of the heat exchanger of FIG. 8A taken along the line d-d'.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. It is to understand that the present invention is not limited to the following embodiments, and those which have appropriately added changes, improvements and the like to the following embodiments based on knowledge of a person skilled in the art without departing from the spirit of the present invention fall within the scope of the present invention.

FIG. 1A is a cross-sectional view of a heat exchanger according to Embodiment 1 of the present invention, which is parallel to an extending direction of cells. FIG. 1B is a cross-sectional view of the heat exchanger of FIG. 1A taken along the line a-a' (a cross-sectional view orthogonal to the extending direction of the cells of the heat exchanger in FIG. 1A).
As shown in FIGS. 1A and 1B, the heat exchanger according to Embodiment 1 of the invention has a first honeycomb structure 10, a first cylindrical member 20, and a second honeycomb structure 30. The first honeycomb structure 10 has an outer peripheral wall 11 and partition walls 13 that are disposed on an inner side of the outer peripheral wall 11 and define a plurality of cells 12 to form flow paths for a first fluid. The first cylindrical member 20 is fitted into the outer peripheral wall 11 of the first honeycomb structure 10. The second honeycomb structure 30 has an outer peripheral wall 31, an inner peripheral wall 35, and partition walls 33 that are disposed between the outer peripheral wall 31 and the inner peripheral wall 35 and that define a plurality of cells 32 to form flow paths for the second fluid. In the second honeycomb structure 30, the inner peripheral wall 35 is fitted into the first cylindrical member 20. The heat exchanger having such a structure can suppress mixing of the first fluid with the second fluid because the first cylindrical member 20 is disposed between the first honeycomb structure 10 through which the first fluid flows, and the second honeycomb structure 30 through which the second fluid flows.
The term "heat exchanger" as used herein refers to a device or a member used to exchange thermal energy between two different fluids (e.g., the first fluid and the second fluid). If the heat exchanger refers to the device, it can further include known members needed to form the device.

(First Honeycomb Structure 10)

The first honeycomb structure 10 has an outer peripheral wall 11 and partition walls 13 that are disposed on an inner side of the outer peripheral wall 11 and define a plurality of cells 12 to form flow paths for a first fluid. The flow path for the first fluid extends from one end face 14a to the other end face 14b.
A shape (outer shape) of the first honeycomb structure 10 is not particularly limited, and it may be, for example, in addition to the circular shape as shown in FIG. 1B, an elliptical shape, a quadrangular shape, or other polygonal shape in a cross section orthogonal to the extending direction of the cells 12.
Each cell 12 may have any shape, including, but not particularly limited to, in addition to the quadrangular shape as shown in FIG. 1B, a circular shape, a elliptical shape, a triangular shape, a hexagonal shape or other polygonal shapes in a cross section orthogonal to the extending direction of the cells 12.
The partition walls 13 preferably have first partition walls 13a each extending in the circumferential direction and second partition walls 13b each extending in the radial direction, as shown in FIG. 1B, in a cross section orthogonal to the extending direction of the cells 12 of the first honeycomb structure 10. Such a configuration allows for efficient heat exchange between the first fluid flowing through the cells 12 of the first honeycomb structure 10 and the second fluid flowing through the cells 32 of the second honeycomb structure 30.
The thickness of the partition walls 13 is not particularly limited, but it may preferably be 0.05 to 1.0 mm, and more preferably 0.2 to 0.6 mm. The thickness of the partition walls 13 of 0.05 mm or more allows the mechanical strength of the first honeycomb structure 10 to be made sufficient. Further, the thickness of the partition walls 13 of 1.0 mm or less can prevent problems that the pressure loss is increased due to a decrease in an opening area and the heat recovery efficiency is decreased due to a decrease in a contact area with the first fluid.
The outer peripheral wall 11 preferably has a thickness larger than that of the partition walls 13, although not particularly limited thereto. Such a structure can lead to increased strength of the outer peripheral wall 11 which would otherwise tend to generate breakage (e.g., cracking, chinking, and the like) by external impact, thermal stress due to a temperature difference between the first fluid and the second fluid, and the like.
In addition, the thickness of the outer peripheral wall 11 is not particularly limited, and it may be adjusted as needed according to applications and the like. For example, the thickness of the outer peripheral wall 11 is preferably 0.1 mm to 10 mm, and more preferably from 0.5 mm to 5 mm, and even more preferably from 1 mm to 3 mm.
The first honeycomb structure 10 (the outer peripheral wall 11 and the partition walls 13) contains ceramics as a main component. The phrase "contain ceramics as a main component" means that a ratio of a mass of ceramics to the total mass of all the components is 50% by mass or more. The ceramics can be used to reduce weight while suppressing rust and deformation.
The ceramics is not limited, but it preferably contains silicon carbide (SiC) as the main component. Examples of the ceramics containing silicon carbide (SiC) as a main component includes Si-impregnated SiC, (Si + Al) impregnated SiC, a metal composite SiC, recrystallized SiC, Si₃N₄, SiC, and the like. Among them, Si-impregnated SiC and (Si + Al) impregnated SiC are preferably used because they can allow production at lower cost and have high thermal conductivity.
Each of the outer peripheral wall 11 and the partition walls 13 preferably has a porosity of 10% or less, and more preferably 5% or less, and even more preferably 3% or less, although not particularly limited thereto. The porosity of the outer peripheral wall 11 and the partition walls 13 of 10% or less can lead to improvement of thermal conductivity.
As used herein, the "porosity" refers to a porosity measured by mercury intrusion technique in accordance with JIS R1655: 2003.
A cell density (that is, the number of cells 12 per unit area) in the cross section of the first honeycomb structure 10 orthogonal to the extending direction of the cells 12 is preferably in a range of from 4 to 320 cells/cm², although not particularly limited thereto. The cell density of 4 cells/cm² or more can sufficiently ensure the strength of the partition walls 13, hence the strength of the first honeycomb structure 10 itself and effective GSA (geometrical surface area). Further, the cell density of 320 cells/cm² or less can allow for prevention of an increase in a pressure loss when the first fluid flows.
The first honeycomb structure 10 preferably has an isostatic strength of 100 MPa or more, and more preferably 150 MPa or more, and still more preferably 200 MPa or more, although not particularly limited thereto. The isostatic strength of the first honeycomb structure 10 of 100 MPa or more can lead to the first honeycomb structure 10 having improved durability.
The "isostatic strength" as used herein can be measured according to the method for measuring isostatic strength as defied in the JASO standard M505-87 which is a motor vehicle standard issued by Society of Automotive Engineers of Japan, Inc.
A diameter (an outer diameter) of the outer peripheral wall 11 of the first honeycomb structure 10 in the cross section orthogonal to the extending direction of the cells 12 may preferably be from 20 to 200 mm, and more preferably from 30 to 150 mm, although not particularly limited thereto. Such a diameter can allow the heat recovery efficiency to be improved. When the shape of the outer peripheral wall 11 is not circular, the diameter of the largest inscribed circle that is inscribed in the cross-sectional shape of the outer peripheral wall 11 is defined as the diameter of the outer peripheral wall 11.
The first honeycomb structure 10 preferably has a thermal conductivity of 50 W/(m·K) or more at 25 °C, and more preferably from 100 to 300 W/(m·K), and even more preferably from 120 to 300 W/(m K), although not particularly limited thereto. The thermal conductivity of the first honeycomb structure 10 in such a range can lead to improved heat conductive properties, and so allows for efficient heat exchange between the first fluid flowing through the cells 12 of the first honeycomb structure 10 and the second fluid flowing through the cells 32 of the second honeycomb structure 30.
As used herein, the "thermal conductivity" is a value measured according to the laser flash method (JIS R 1611-2010).

(Second Honeycomb Structure 30)

The second honeycomb structure 30 has an outer peripheral wall 31, an inner peripheral wall 35, and partition walls 33 that are disposed between the outer peripheral wall 31 and the inner peripheral wall 35 and that define a plurality of cells 32 to form flow paths for the second fluid. The flow path for the second fluid extends from one end face 34a to the other end face 34b.
Both of the end faces 34a, 34b of the second honeycomb structure 30 are preferably located on inner sides of the first honeycomb structure 10 and the second honeycomb structure 30 in the axial direction (the extending direction of the cells 12, 32) than the end faces 14a, 14b of the first honeycomb structure 10. This configuration makes it easier to provide the inflow port (e.g., end face 34b) and outflow port (e.g., end face 34a) of the second fluid flowing through the second honeycomb structure 30, while avoiding the flow of the first fluid.
The second honeycomb structure 30 may be divided into multiple portions in the cross section orthogonal to the extending direction of the cells 32. By dividing the second honeycomb structure 30 into multiple portions, the heat exchanger is easily produced.
Here, each of FIGS. 2A and 2B shows a cross-sectional view of a heat exchanger having a second honeycomb structure 30 divided into multiple portions, which is orthogonal to the extending direction of the cells. FIG. 2A is an example of a heat exchanger having a second honeycomb structure 30 divided into four portions, and FIG. 2B is an example of a heat exchanger having a second honeycomb structure 30 divided into two portions.
The number of divisions of the second honeycomb structure 30 is not limited, but it is typically 2 to 10. The sizes of the divided individual second honeycomb structures 30 may be the same or different.
The external shape of the second honeycomb structure 30 (shape of the outer peripheral wall 31) is not particularly limited, and it can be the circular shape as shown in FIG. 1B, as well as oval, quadrangular, or other polygonal shapes in the cross section orthogonal to the extending direction of the cells 32.
The internal shape of the second honeycomb structure 30 (shape of the inner peripheral wall 35) is also not particularly limited, and it can be the circular shape as shown in FIG. 1B, as well as oval, quadrangular, or other polygonal shapes in the cross section orthogonal to the extending direction of the cells 32.
It should be note that the external shape and the internal shape of the first honeycomb structure 30 may be the same as or different from each other. However, they are preferably the same as each other, in terms of resistance to external impact, thermal stress, and the like. When the second honeycomb structure 30 is divided into multiple portions, the external and internal shapes of the second honeycomb structure 30 mean the external and internal shapes of the combination of the divided second honeycomb structures 30.
Each cell 32 may have any shape, including, but not particularly limited to, in addition to the quadrangular shape as shown in FIG. 1B, a circular shape, a elliptical shape, a triangular shape, a hexagonal shape or other polygonal shapes in the cross section orthogonal to the extending direction of the cells 32.
The partition walls 33 preferably have first partition walls 33a each extending in the circumferential direction and second partition walls 33b each extending in the radial direction, as shown in FIG. 1B, in the cross section orthogonal to the extending direction of the cells 32 of the second honeycomb structure 30. Such a configuration allows for efficient heat exchange between the first fluid flowing through the cells 12 of the first honeycomb structure 10 and the second fluid flowing through the cells 32 of the second honeycomb structure 30.
The thickness of the partition walls 33 is not particularly limited, but it may preferably be 0.05 to 1.0 mm, and more preferably 0.2 to 0.6 mm. The thickness of the partition walls 33 of 0.05 mm or more can provide the second honeycomb structure 30 with a sufficient mechanical strength. Further, the thickness of the partition walls 33 of 1 mm or less can prevent problems that the pressure loss is increased due to a decrease in an opening area and the heat recovery efficiency is decreased due to a decrease in a contact area with the second fluid.
Each of the outer peripheral wall 31 and the inner peripheral wall 35 preferably has a thickness larger than that of the partition wall 33, although not particularly limited thereto. Such a structure can lead to increased strength of the outer peripheral wall 31 and the inner peripheral wall 35 which would otherwise tend to generate breakage (e.g., cracking, chinking, and the like) by external impact, thermal stress due to a temperature difference between the first fluid and the second fluid, and the like.
In addition, the thicknesses of the outer peripheral wall 31 and the inner peripheral wall 35 are not particularly limited, and they may be adjusted as needed according to applications and the like. For example, the thickness of each of the outer peripheral wall 31 and the inner peripheral wall 35 is preferably 0.1 mm to 10 mm, and more preferably from 0.5 mm to 5 mm, and even more preferably from 1 mm to 3 mm.
The second honeycomb structure 30 (the outer peripheral wall 31, the inner peripheral wall 35 and the partition walls 33) preferably contain ceramics as a main component. The phrase "contain ceramics as a main component" means that a ratio of a mass of ceramics to the masses of the total components is 50% by mass or more. The ceramics can be used to reduce weight while suppressing rust and deformation.
The ceramics are not limited, but it preferably contains silicon carbide (SiC) as the main component. Examples of the ceramics containing silicon carbide (SiC) includes Si-impregnated SiC, (Si + Al) impregnated SiC, a metal composite SiC, recrystallized SiC, Si₃N₄, SiC, and the like. Among them, Si-impregnated SiC and (Si + Al) impregnated SiC are preferably used because they can allow production at lower cost and have high thermal conductivity.
Each of the outer peripheral wall 31, the inner peripheral wall 35 and the partition walls 33 preferably has a porosity of 10% or less, and more preferably 5% or less, and even more preferably 3% or less, although not particularly limited thereto. The porosity of the outer peripheral wall 31, the inner peripheral wall 35 and the partition walls 33 of 10% or less can lead to improvement of thermal conductivity.
A cell density (that is, the number of cells 32 per unit area) of the second honeycomb structure 30 in the cross section orthogonal to the extending direction of the cells 32 is preferably in a range of from 4 to 320 cells/cm², although not particularly limited thereto. The cell density of 4 cells/cm² or more can sufficiently ensure the strength of the partition walls 33, hence the strength of the second honeycomb structure 30 itself and effective GSA (geometrical surface area). Further, the cell density of 320 cells/cm² or less can allow for prevention of an increase in a pressure loss when the second fluid flows.
The second honeycomb structure 30 preferably has an isostatic strength of 100 MPa or more, and more preferably 150 MPa or more, and still more preferably 200 MPa or more, although not particularly limited thereto. The isostatic strength of the second honeycomb structure 30 of 100 MPa or more can lead to the second honeycomb structure 30 having improved durability.
A diameter (an outer diameter) of the outer peripheral wall 31 of the second honeycomb structure 30 in the cross section orthogonal to the extending direction of the cells 32 may preferably be from 30 to 400 mm, and more preferably from 40 to 300 mm, although not particularly limited thereto. Such a diameter can allow the heat recovery efficiency to be improved. When the shape of the outer peripheral wall 31 is not circular, the diameter of the largest inscribed circle that is inscribed in the cross-sectional shape of the outer peripheral wall 31 is defined as the diameter of the outer peripheral wall 31.
Further, a diameter (inner diameter) of the inner peripheral wall 35 of the second honeycomb structure 30 in the cross section orthogonal to the extending direction of the cells 32 may preferably be from 20 to 200 mm, and more preferably from 30 to 150 mm, although not particularly limited thereto. When the cross-sectional shape of the inner peripheral wall 35 is not circular, the diameter of the largest inscribed circle that is inscribed in the cross-sectional shape of the inner peripheral wall 35 is defined as the diameter of the inner peripheral wall 35.
When the second honeycomb structure 30 is divided into multiple portions, the diameters of the outer peripheral wall 31 and the inner peripheral wall 35 mean the diameters of the outer peripheral wall 31 and the inner peripheral wall 35 with the divided second honeycomb structures 30 combined.
The second honeycomb structure 30 preferably has a thermal conductivity of 50 W/(m·K) or more at 25 °C, and more preferably from 100 to 300 W/(m·K), and even more preferably from 120 to 300 W/(m K), although not particularly limited thereto. The thermal conductivity of the second honeycomb structure 30 in such a range can lead to an improved thermal conductivity and can efficiently exchange the heat between the first fluid flowing through the cells 12 of the first honeycomb structure 10 and the second fluid flowing through the cells 32 of the second honeycomb structure 30.

(First Cylindrical Member 20)

The first cylindrical member 20 is disposed between the outer peripheral wall 11 of the first honeycomb structure 10 and the inner peripheral wall 35 of the second honeycomb structure 30.
The first cylindrical member 20 is a cylindrical member with two end portions 21a, 21b, through which the first fluid can circulate.
Both end portions 21a, 21b of the first cylindrical member 20 are preferably located on outer sides of the two end faces 14a, 14b of the first honeycomb structure 10 and the two end faces 34a, 34b of the second honeycomb structure 30 in the axial direction (the extending direction of the cells 12, 32) of the first honeycomb structure 10 and the second honeycomb structure 30. This configuration makes it easier to provide the inflow port (e.g., the end portion 21a) and the outflow port (e.g., the end portion 21b) for the first fluid flowing through the first cylindrical member 20 while avoiding the flow of the second fluid.
The first cylindrical member 20 is preferably made of a metal material from the viewpoint of heat conductive properties and manufacturability. Examples of the material that can be used herein include stainless steel, titanium alloys, copper alloys, aluminum alloys, brass, nickel alloys, steel, lead, lead alloys, and the like. Among them, the stainless steel is preferable because it is inexpensive and has high durability. From the viewpoint of improving the corrosion resistance of the first cylindrical member 20, a surface treatment such as fluoroplastic lining or FRP lining may be applied to the first cylindrical member 20.
The thickness of the first cylindrical member 20 is preferably 0.1 mm or more, more preferably 0.5 mm or more, even more preferably 1 mm or more, from the viewpoint of stably suppressing mixing of the first fluid with the second fluid. The thickness of the first cylindrical member 20 is preferably 50 mm or less, and more preferably 40 mm or less, and still more preferably 30 mm or less, from the viewpoints of cost, volume, weight, and the like.
For the first cylindrical member 20, at least one of the end portions 21a, 21b may have a decreased or increased diameter. Here, FIG. 3A shows an example in which both end portions 21a, 21b of the first cylindrical member 20 have the increased diameter, and FIG. 3B shows an example in which both end portions 21a, 21b of the first cylindrical member 20 has the decreased diameter. FIGS. 3A and 3B are cross-sectional views orthogonal to the extending direction of the cells 12, 32.
By decreasing or increasing the diameters of both end portions 21a, 21b of the first cylindrical member 20, advantageous effects, such as ease to connect to other members, can be produced in terms of production.
Although FIGS. 3A and 3B show the examples in which both end portions 21a, 21b have the decreased or increased diameters, but one of the end portions 21a, 21b may have the decreased or increased diameter.

(First Fluid and Second Fluid)

The first fluid and the second fluid are not limited and they can be gases, liquids, and the like. Typical first and second fluids are gases. For example, the first fluid is an exhaust gas emitted in the industrial field, and the second fluid is various gases that require heating.
The flow direction of the first fluid is preferably opposite to that of the second fluid. Such flow direction can allow for improvement of heat recovery efficiency between the first fluid and the second fluid.

The production method of the heat exchanger is not particularly limited, and the heat exchanger can be produced in accordance with methods known in the art. For example, the heat exchanger can be produced in accordance with the producing method as described below.
First, each honeycomb structure (the first honeycomb structure 10 and the second honeycomb structure 30) is produced. Each honeycomb structure is produced as follows: First, a green body containing ceramic powder is extruded into a desired shape to prepare a honeycomb formed body. At this time, the shape and density of the cells 12, 32, and lengths and thicknesses of the outer peripheral wall 11, 31, the partition walls 13, 33 and the inner peripheral wall 35, and the like, can be controlled by selecting dies and jigs in appropriate forms. The material of the honeycomb formed body that can be used herein includes the ceramics as described above. For example, when producing a honeycomb formed body containing the Si-impregnated SiC composite as a main component, a binder and water or an organic solvent are added to a predetermined amount of SiC powder, and the resulting mixture is kneaded to form a green body, which can be then formed into a honeycomb formed body having a desired shape. The resulting honeycomb formed body can be then dried, and the honeycomb formed body can be impregnated with metal Si and fired under reduced pressure in an inert gas or in vacuum to obtain each honeycomb structure.
The first honeycomb structure 10 is then inserted into the first cylindrical member 20, and the first cylindrical member 20 is fitted into the outer peripheral wall 11 of the first honeycomb structure 10 to obtain a joined body of the first honeycomb structure 10 and the first cylindrical member 20. The joined body is then inserted into the inner peripheral wall 35 of the second honeycomb structure 30, and the first cylindrical member 20 of the joined body is fitted into the inner peripheral wall 35 of the second honeycomb structure 30.
Further, the arranging and fitting orders of the respective members are not limited to the above orders, and they may be changed as needed within a range in which the members can be produced. As the fitting method, the above method may be used.

FIG. 4A is a cross-sectional view of a heat exchanger according to Embodiment 2 of the present invention, which is parallel to an extending direction of cells. FIG. 4B is a cross-sectional view of the heat exchanger in FIG. 4A taken along the line b-b' (a cross-sectional view orthogonal to the extending direction of the cells of the heat exchanger in FIG. 4A).
In FIGS. 4A and 4B, components indicated by the same reference numerals as in the above figures indicate the same components as in these figures, and detailed descriptions thereof are omitted.
The heat exchanger according to Embodiment 2 of the present invention is further provided with a heat conductive material 40 disposed between the first honeycomb structure 10 and the first cylindrical member 20 and/or between the second honeycomb structure 30 and the first cylindrical member 20. This configuration can improve the heat exchange efficiency between the first fluid flowing through the cells 12 of the first honeycomb structure 10 and the second fluid flowing through the cells 32 of the second honeycomb structure 30.
Although FIGS. 4A and 4B show an example in which the heat conductive materials 40 are disposed both between the first honeycomb structure 10 and the first cylindrical member 20 and between the second honeycomb structure 30 and the first cylindrical member 20, the heat conductive material 40 may be disposed between the first honeycomb structure 10 and the first cylindrical member 20 or between the second honeycomb structure 30 and the first cylindrical member 20.
The heat conductive material 40 is not limited as long as it has heat conductive properties, and examples include graphite sheets and thermally conductive resin sheets.
The heat exchanger 100 according to Embodiment 2 can be produced in accordance with a known method in the art. Specifically, the heat conductive material(s) 40 can be placed between the first honeycomb structure 10 and the first cylindrical member 20 and/or between the second honeycomb structure 30 and the first cylindrical member 20 during the placement and fitting of each component.

FIG. 5 is a cross-sectional view of a heat exchanger according to Embodiment 3 of the present invention, which is parallel to an extending direction of cells.
In FIG. 5, components indicated by the same reference numerals as those in the above figures indicate the same components as those in the above figures, and thus detailed descriptions thereof are omitted.
The heat exchanger according to Embodiment 3 of the present invention is further provided with a second cylindrical member 50 that is fitted into at least a part of the outer peripheral wall 31 of the second honeycomb structure 30. The second cylindrical member 50 has an inflow port 51 and a discharge port 52 for the second fluid. This configuration makes it easier to provide the inflow port 51 and the discharge port 52 for the second fluid while avoiding the flow of the first fluid.
The second cylindrical member 50 is preferably made of a metal in terms of manufacturability. Examples of the material that can be used herein include stainless steel, titanium alloys, copper alloys, aluminum alloys, brass, nickel alloys, steel, lead, lead alloys, sand the like. Among them, the stainless steel is preferable because it is inexpensive and has high durability. From the viewpoint of improving the corrosion resistance of the second cylindrical member 50, a surface treatment such as fluoroplastic lining or FRP lining may be applied to the second cylindrical member 50.
The thickness of the second cylindrical member 50 is preferably 0.1 mm or more, and more preferably 0.5 mm or more, and still more preferably 1 mm or more, in terms of durability. The thickness of the second cylindrical member 50 is preferably 50 mm or less, and more preferably 40 mm or less, and still more preferably 30 mm or less, from the viewpoints of cost, volume, and weight, and the like.
Between the second honeycomb structure 30 and the second cylindrical member 50 may be a heat insulating material, as shown in FIG. 6. The heat insulating material 60 can suppress heat dissipation from the second cylindrical member 50 to the external space, thus improving the heat exchange efficiency between the first fluid flowing through the cells 12 of the first honeycomb structure 10 and the second fluid flowing through the cells 32 of the second honeycomb structure 30.
FIG. 6 is a cross-sectional view of the heat exchanger, which is parallel to the extending direction of the cells.
The heat insulating material 60 is not limited as long as it is any material having heat-insulating properties, and includes glass wool, rock wool, cellulose fiber, and the like.
The heat exchanger 100 according to Embodiment 3 can be produced in accordance with a known method in the art. Specifically, the second cylindrical member 50 can be fitted into the outer peripheral wall 31 of the second honeycomb structure 30. Further, the arranging and fitting orders of the respective members are not limited to the above orders, and they may be changed as needed within a range in which the members can be produced. As the fitting method, the above method may be used.

FIG. 7A is a cross-sectional view of a heat exchanger according to Embodiment 4 of the present invention, which is parallel to an extending direction of cells. FIG. 7B is a cross-sectional view of the heat exchanger in FIG. 7A taken along the line c-c' (a cross-sectional view orthogonal to the extending direction of the cells of the heat exchanger in FIG. 7A).
In FIGS. 7A and 7B, components indicated by the same reference numerals as in the above figures indicate the same components as in these figures, and thus detailed descriptions are omitted.
The heat exchanger according to Embodiment 4 of the invention has a first honeycomb structure 10 further having an inner peripheral wall 15 that forms a hollow region therein, which serves as a flow path for a third fluid. This configuration allows for heat exchange between the first fluid and the third fluid through the inner peripheral wall 15.
The inner peripheral wall 15 preferably has a thickness larger than that of the partition wall 13, although not particularly limited thereto. Such a structure can lead to increased strength of the inner peripheral wall 15 which would otherwise tend to generate breakage (e.g., cracking, chinking, and the like) by thermal stress due to a temperature difference between the first fluid and the third fluid, and the like.
In addition, the thicknesses of the inner peripheral wall 15 is not particularly limited, and it may be adjusted as needed according to applications and the like. For example, the thickness of the inner peripheral wall 15 is preferably 0.1 mm to 10 mm, and more preferably from 0.5 mm to 5 mm, and even more preferably from 1 mm to 3 mm.
The inner peripheral wall 15 may have any shape, including, but not particularly limited to, the circular shape as shown in FIG. 7B, as well as elliptical, quadrangular or other polygonal shapes in the cross section orthogonal to the extending direction of the cells 12. It should be note that the shape of the outer peripheral wall 11 and the shape of the inner peripheral wall 15 may be the same as or different from each other. However, they are preferably the same as each other, in terms of resistance to thermal stress, and the like.
Further, a diameter (inner diameter) of the inner peripheral wall 15 in the cross section orthogonal to the extending direction of the cells 12 may preferably be from 150 mm or less, and more preferably 100 mm or less, although not particularly limited thereto. When the cross-sectional shape of the inner peripheral wall 15 is not circular, the diameter of the largest inscribed circle that is inscribed in the cross-sectional shape of the inner peripheral wall 15 is defined as the diameter of the inner peripheral wall 15.
The third fluid is not limited and it can be a gas or a liquid. A typical third fluid is a gas. For example, the third gas may be various gases that require heating as the third fluid.
The flow direction of the first fluid is preferably opposite to the flow direction of the third fluid. Such a flow direction can allow for improvement of heat recovery efficiency.
The heat exchanger according to Embodiment 4 of the present invention may further be provided with a third cylindrical member 70 that is fitted into at least a part of the inner wall 15 of the first honeycomb structure 10.
Here, FIG. 8A shows a cross-sectional view of the heat exchanger having the third cylindrical member 70, which is parallel to the extending direction of the cells, and FIG 8B shows a cross-sectional view of the heat exchanger in FIG. 8A taken along the line d-d' (a cross-sectional view orthogonal to the extending direction of the cells of the heat exchanger in FIG. 8A).
As shown in FIGS. 8A and 8B, the heat exchanger further includes a third cylindrical member 70 that is fitted into at least a part of the inner peripheral wall 15 of the first honeycomb structure 10. The third cylindrical member 70 has an inflow port 71 and a discharge port 72 for the third fluid. Such a structure can stably suppress the mixing of the first fluid with the third fluid.
The inflow port (end portion) 71 and the discharge port (end portion) 72 of the third cylindrical member 70 are preferably located on outer sides of the two end portions 21a, 21b of the first cylindrical member 20 and the third cylindrical member 70 in the axial direction. This configuration makes it easier to provide the inflow port 71 and the discharge port 72 of the third fluid while avoiding the flow of the first fluid.
The third cylindrical member 70 is preferably made of a metal material from the viewpoint of thermal conductivity and manufacturability. Examples of the material that can be used herein include stainless steel, titanium alloys, copper alloys, aluminum alloys, brass, nickel alloys, steel, lead, lead alloys, sand the like. Among them, the stainless steel is preferable because it is inexpensive and has high durability. From the viewpoint of improving the corrosion resistance of the third cylindrical member 70, a surface treatment such as fluoroplastic lining or FRP lining may be applied to the third cylindrical member 70.
The thickness of the third cylindrical member 70 is preferably 0.1 mm or more, and more preferably 0.5 mm or more, and even more preferably 1 mm or more, from the viewpoint of stably suppressing the mixing of the first fluid with the third fluid. The thickness of the third cylindrical member 70 is preferably 50 mm or less, and more preferably 40 mm or less, and still more preferably 30 mm or less, from the viewpoints of cost, volume, and weight, and the like.
For the third cylindrical member 70, at least one end portion (inflow port 71, discharge port 72) may have a decreased or increased diameter. By decreasing or increasing the diameters of the end portions of the third cylindrical member 70, advantageous effects, such as ease to connect to other members, can be produced in terms of production.
The heat exchanger 100 according to Embodiment 4 can be produced in accordance with a known method in the art. Specifically, it can be produced by the same method as that of the heat exchanger according to Embodiment 1 of the present invention, with the exception that the honeycomb formed body is produced by selecting dies and jigs having appropriate forms so that the first honeycomb structure 10 having the inner peripheral wall 15 is obtained. When the third cylindrical member 70 is provided, the third cylindrical member 70 can be fitted into the inner peripheral wall 15 of the first honeycomb structure 10. The arranging and fitting orders of the respective members are not limited to the above orders, and they may be changed as needed within a range in which the members can be produced. As the fitting method, the above method may be used.

DESCRIPTION OF REFERENCE NUMERALS

10 first honeycomb structure
11 outer peripheral wall
12 cell
13 partition wall
13a first partition wall
13b second partition wall
14a, 14b end faces
15 inner peripheral wall
20 first cylindrical member
21a, 21b end portions
30 second honeycomb structure
31 outer peripheral wall
32 cell
33 partition wall
33a first partition wall
33b second partition wall
34a, 34b end faces
35 inner peripheral wall
40 heat conductive material
50 second cylindrical member
51 inflow port
52 discharge port
60 heat insulating material
70 third cylindrical member
71 inflow port
72 discharge port

Claims

A heat exchanger, comprising:
a first honeycomb structure (10) having an outer peripheral wall (11) and partition walls (13) disposed on an inner side of the outer peripheral wall (11), the partition walls (13) defining a plurality of cells (12) to form flow paths for a first fluid;

a first cylindrical member (20) fitted into the outer peripheral wall (11) of the first honeycomb structure (10); and

a second honeycomb structure (30) having an outer peripheral wall (31), an inner peripheral wall (35), and partition walls (33) disposed between the outer peripheral wall (31) and the inner peripheral wall (35), the partition walls (33) defining a plurality of cells (32) to form flow paths for a second fluid, wherein the inner peripheral wall (35) is fitted into the first cylindrical member (20).
The heat exchanger according to claim 1, further comprising a heat conductive material (40) disposed between the first honeycomb structure (10) and the first cylindrical member (20) and/or between the second honeycomb structure (30) and the first cylindrical member (20).
The heat exchanger according to claim 1 or 2, wherein both end faces (34a, 34b) of the second honeycomb structure (30) are located on inner sides of both end faces (14a, 14b) of the first honeycomb structure (10) in an axial direction of the first honeycomb structure (10) and the second honeycomb structure (30).
The heat exchanger according to any one of claims 1 to 3, wherein both end portions (21a, 21b) of the first cylindrical member (20) are located on outer sides of both end faces(14a, 14b, 34a, 34b) of the first honeycomb structure (10) and the second honeycomb structure (30) in an axial direction of the first honeycomb structure (10) and the second honeycomb structure (30).
The heat exchanger according to any one of claims 1 to 4, wherein, in a cross section orthogonal to an extending direction of the cells (12, 32) of the first honeycomb structure (10) and the second honeycomb structure (30), the partition walls (13, 33) have first partition walls (13a, 33a) each extending in a circumferential direction and second partition walls (13b, 33b) each extending in a radial direction.
The heat exchanger according to any one of claims 1 to 5, wherein the second honeycomb structure is (30) divided into multiple portions in a cross section orthogonal to an extending direction of the cells (32) of the second honeycomb structure (30).
The heat exchanger according to any one of claims 1 to 6, wherein the first honeycomb structure (10) and/or the second honeycomb structure (30) contain ceramics as a main component.
The heat exchanger according to claim 7, wherein the ceramics contains silicon carbide as a main component.
The heat exchanger according to any one of claims 1 to 8, wherein the first cylindrical member (20) is made of a metal material.
The heat exchanger according to any one of claims 1 to 9, wherein at least one end portion (21a, 21b) of the first cylindrical member (20) has a decreased or increased diameter.
The heat exchanger according to any one of claims 1 to 10, further comprising a second cylindrical member (50) fitted into at least a part of the outer peripheral wall (31) of the second honeycomb structure (30), wherein the second cylindrical member (50) has an inflow port (51) and a discharge port (52) for the second fluid.
The heat exchanger according to claim 11, further comprising a heat insulating material disposed between the second honeycomb structure (30) and the second cylindrical member (50).
The heat exchanger according to any one of claims 1 to 12, wherein the flow direction of the first fluid and the flow direction of the second fluid are opposite to each other.
The heat exchanger according to any one of claims 1 to 13, wherein the first honeycomb structure (10) further comprises an inner peripheral wall (15) that forms a hollow region therein, the hollow region serving as a flow path for a third fluid.
The heat exchanger according to claim 14, further comprising a third cylindrical member (70) fitted into at least a part of the inner peripheral wall (15) of the first honeycomb structure (10), wherein the third cylindrical member (70) has an inflow port (71) and a discharge port (72) for the third fluid.