JP2014070826A - Heat exchange member and heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanging member and a heat exchanger in which a heat exchange efficiency is improved and an increasing of pressure loss is restricted.SOLUTION: A honeycomb structure 1 acting as a heat exchanging member has several cells 3 partitioned by ceramics partition walls 4, axially passing from one end surface to the other end surface to cause a first fluid to flow therein. When a coefficient of thermal conductivity of material quality of the partition walls 4 of the honeycomb structure 1 is defined as λ[W/K.m], a wall thickness of the partition wall 4 of the cell structure of the honeycomb structure 1 is defined as t[mm] and a cell density is defined as ρ[pcs./sq.inch], it will be defined as 1000/λ≤t×ρ≤80.

Description

  The present invention relates to a heat exchange member for exchanging heat of a first fluid and heat of a second fluid, and a heat exchanger.

  There is a demand for heat recovery technology from high-temperature gas such as combustion exhaust gas from engines. As the gas / liquid heat exchanger, a tube-type heat exchanger with fins such as an automobile radiator or an air conditioner outdoor unit is generally used. However, in order to recover heat from a gas such as automobile exhaust gas, a general metal heat exchanger has poor heat resistance and is difficult to use at high temperatures. Therefore, a heat-resistant metal or ceramic material having heat resistance, heat shock, corrosion resistance, or the like is suitable. Heat exchangers made of refractory metals are known, but refractory metals have problems such as high price and difficulty in processing, high density and heavy, and low heat conduction.

  Patent Document 1 discloses a heat exchanger using a honeycomb structure formed of ceramics. In the heat exchanger disclosed in Patent Document 1, heat is exchanged between the heat of the first fluid flowing through the cells of the honeycomb structure and the heat of the second fluid flowing on the outer peripheral surface of the honeycomb structure.

International Publication No. 2011/071161

  Exhaust heat recovery device that exchanges heat between exhaust and cooling water (a heat exchanger that transfers heat from a high-temperature fluid to a low-temperature fluid by flowing a high-temperature fluid and a low-temperature fluid next to each other across a wall), or an EGR cooler In the field, the performance of heat exchange efficiency is regarded as important. In order to improve the heat exchange efficiency, it is preferable to increase the partition wall thickness and cell density of the honeycomb structure used in these devices.

  However, in the case of a device used for an automobile exhaust system, not only heat exchange efficiency but also pressure loss of the device is regarded as important. The direction in which the partition wall thickness and cell density of the honeycomb structure are increased is the direction in which the pressure loss is worsened, which may adversely affect the engine output. In particular, when the displacement is large or when these devices are used at a high gas temperature, the influence becomes large.

  An object of the present invention is to provide a heat exchange member and a heat exchanger that improve heat exchange efficiency and suppress an increase in pressure loss.

  The present inventors have found that when the honeycomb structure is used as a heat exchange member, the above problem can be solved by defining the relationship between the thermal conductivity of the honeycomb structure, the wall thickness, and the cell density. It was. That is, according to the present invention, the following heat exchange member and heat exchanger are provided.

[1] A honeycomb structure having a plurality of cells partitioned by ceramic partition walls and penetrating in an axial direction from one end face to the other end face, and serving as a first fluid circulation portion through which a heating body as a first fluid circulates. A second fluid which is formed as a body and exchanges heat with the first fluid by flowing on the outer peripheral surface of the outer peripheral wall of the honeycomb structure and the first fluid flowing through the first fluid circulation portion. At least one of the partition walls and the outer peripheral wall of the honeycomb structure is made dense so as not to mix with fluid, and the thermal conductivity of the material of the partition walls of the honeycomb structure is λ [W / K · m]. In the honeycomb structured cell structure, a heat exchange member satisfying 1000 / λ ≦ t × ρ ≦ 80 when the wall thickness of the partition wall is t [mm] and the cell density is ρ [pieces / square inch].

[2] The heat exchange member according to [1], wherein t> 0.2 and ρ ≦ 100.

[3] The heat exchange member according to [1], wherein t ≦ 0.2 and ρ> 100.

[4] When the equivalent circular diameter of the cross-sectional area of the cross section perpendicular to the axial direction of the honeycomb structure is Φ [mm] and the total length of the axial length of the honeycomb structure is L [mm], 15 The heat exchange member according to any one of [1] to [3], wherein ≦ Φ ≦ 120 and 0.05 ≦ L / Φ ≦ 10.

[5] A metal tube is provided on the outer peripheral side of the honeycomb structure, the first fluid is circulated inside the honeycomb structure, and the second fluid is circulated on the outer peripheral surface side of the metal tube. The heat exchange member according to any one of [1] to [4], wherein heat exchange is performed between the first fluid and the second fluid.

[6] The heat exchange member according to [5], further including an intermediate member sandwiched between the honeycomb structure and the metal tube.

[7] The heat exchange member according to [6], wherein the intermediate material is made of a graphite sheet.

[8] The heat exchange member according to any one of [1] to [7], wherein the honeycomb structure has a thermal conductivity of 100 W / m · K or more.

[9] The heat exchange member according to any one of [1] to [8], wherein the honeycomb structure includes silicon carbide as a main component.

[10] The heat exchange member according to any one of [1] to [9], and a casing in which an inlet and an outlet of the second fluid are formed, and the honeycomb structure is included therein, The inside of the casing serves as a second fluid circulation part, and the second fluid circulates on the outer peripheral surface of the honeycomb structure in the second fluid circulation part, thereby receiving heat from the first fluid. Exchanger.

  The heat exchange member and the heat exchanger of the present invention are not complicated in structure, and realize a reduction in size, weight, and cost as compared with a conventional heat exchanger (heat exchanger or a device thereof). Can do. Moreover, the heat exchange efficiency is high and pressure loss is suppressed. In other words, the heat exchange member of the present invention has high heat exchange efficiency per unit pressure loss value. That is, improving the heat exchange efficiency and suppressing the increase in pressure loss are not easy to achieve both because the directionality is opposite, the heat exchange member of the present invention is excellent in these balances ing.

It is a perspective view which shows the heat exchange member formed as a cylindrical honeycomb structure. It is sectional drawing which cut | disconnected by the cross section parallel to an axial direction which shows the heat exchange member formed as a cylindrical honeycomb structure. It is a perspective view showing a heat exchanger in which a heat exchange member formed as a cylindrical honeycomb structure is accommodated in a casing. It is sectional drawing cut | disconnected in the cross section parallel to an axial direction which shows the heat exchanger in which the heat exchange member formed as a cylindrical honeycomb structure was accommodated in the casing. It is sectional drawing which cut | disconnected in the cross section perpendicular | vertical to an axial direction which shows the heat exchanger in which the heat exchange member formed as a cylindrical honeycomb structure was accommodated in the casing. It is a perspective view which shows the heat exchange member of other embodiment of this invention. It is sectional drawing which cut | disconnected in the cross section parallel to an axial direction which shows the heat exchange member of other embodiment of this invention. It is the schematic diagram seen from the one end surface of the axial direction which shows the heat exchange member of other embodiment of this invention. It is a schematic diagram which shows one Embodiment of the heat exchanger containing the heat exchange member of other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the invention.

(Embodiment 1)
FIG. 1A is a perspective view showing a heat exchange member 10 according to an embodiment of the present invention, FIG. 1B is a cross-sectional view cut along a cross section parallel to the axial direction, and the heat exchange member 10 is a cylindrical honeycomb. It is formed as a structure 1. 2A is a perspective view of the heat exchanger 30 in which the heat exchange member of the cylindrical honeycomb structure 1 is accommodated in the casing 21, and FIG. 2B is a cross-sectional view cut along a cross section parallel to the axial direction. 2C shows a cross-sectional view cut along a cross section perpendicular to the axial direction.

  As shown in FIGS. 1A to 1B, the heat exchange member 10 is partitioned by a ceramic partition wall 4 and penetrates in an axial direction from one end surface 2 to the other end surface 2, and a heating body as a first fluid flows. It is formed as a honeycomb structure 1 having a plurality of cells 3 to be the first fluid circulation part 5. The first fluid flowing through the first fluid circulation portion 5 and the second fluid that exchanges heat with the first fluid by flowing on the outer peripheral surface 7h of the outer peripheral wall 7 of the honeycomb structure 1 are not mixed. Thus, at least one of the partition walls 4 and the outer peripheral wall 7 of the honeycomb structure 1 is made dense. The second fluid flowing on the outer peripheral surface 7h of the honeycomb structure 1 includes the case where the second fluid is in direct contact with the outer peripheral surface 7h of the honeycomb structure 1 and the case where it is not in direct contact. In the present specification, the dense substance (dense body) refers to a substance having a porosity of 20% or less.

  Further, the first fluid circulation portion 5 is formed as a honeycomb structure, and in the case of the honeycomb structure, when the fluid passes through the cell 3, the fluid cannot flow into another cell 3 by the partition wall 4, and the honeycomb structure. The fluid advances linearly from the inlet of the structure 1 to the outlet. Moreover, the honeycomb structure 1 in the heat exchanger 30 of the present invention is not plugged, so that the heat transfer area of the fluid can be increased and the size of the heat exchanger can be reduced. Thereby, the amount of heat transfer per unit volume of the heat exchanger can be increased. Furthermore, since it is not necessary to process the honeycomb structure 1 such as forming plugged portions or forming slits, the heat exchanger 30 can reduce the manufacturing cost.

  The heat exchange member 10 of the present invention has a thermal conductivity λ [W / K · m] of the material of the partition walls 4 of the honeycomb structure 1 that forms the first fluid circulation part 5, and the cell structure of the honeycomb structure 1. When the wall thickness of the partition wall 4 is t [mm] and the cell density is ρ [pieces / square inch], 1000 / λ ≦ t × ρ ≦ 80.

  t × ρ is preferably 1200 / λ ≦ t × ρ ≦ 65, and more preferably 1500 / λ ≦ t × ρ ≦ 50. By setting t × ρ in such a range, the heat of the first fluid flowing in the cell 3 is exchanged with the second fluid flowing on the outer peripheral surface 7 h of the outer peripheral wall 7. The pressure can be efficiently transmitted to the wall 7, and the pressure loss generated by the first fluid can be reduced while maintaining the heat exchange efficiency.

  The heat exchange member 10 preferably further satisfies t> 0.2 and ρ ≦ 100. Alternatively, it is preferable that t ≦ 0.2 and ρ> 100. When the wall thickness of the partition wall 4 is t> 0.2, the heat conduction path is increased by the thickness of the partition wall 4 to increase the heat exchange efficiency, and the cell density ρ is decreased (ρ ≦ 100) to suppress the pressure loss. be able to. When the wall thickness of the partition wall 4 is t <0.2, the pressure loss is suppressed by reducing the wall thickness of the partition wall 4 and the heat conduction path is increased by increasing the cell density ρ (ρ> 100). The heat exchange efficiency can be increased. By setting the ranges of t and ρ as described above, the pressure loss of the heat exchange member 10 can be suppressed and the heat exchange efficiency can be increased.

  The heat exchange member 10 of the present invention preferably satisfies 15 ≦ Φ ≦ 120, where Φ [mm] is the equivalent circle diameter, which is the diameter of a circle having the same area as the area of the heat collecting portion of the honeycomb structure 1. 30 ≦ Φ ≦ 100 is more preferable. Further, when the total length of the honeycomb structure 1 in the axial direction is L [mm], 0.05 ≦ L / Φ ≦ 10 is preferable, and 0.1 ≦ L / Φ <5. Is more preferable.

  The heat collection portion refers to a portion that collects heat from the first fluid. In the honeycomb structure 1, the portion in which the cells 3 are formed (excluding the outer peripheral wall 7). And if the honeycomb structure 1 is a column shape, the diameter of the part except the outer peripheral wall 7 will be (PHI). If the cross-sectional area of the cross section perpendicular to the axial direction of the honeycomb structure 1 is the same, the average distance from each point of the heat collecting portion to the outer peripheral wall 7 is the same regardless of the shape of the honeycomb structure 1. The amount is almost the same. For this reason, the heat exchange efficiency can be improved by defining the parameter including the equivalent circle diameter.

  By setting Φ and L / Φ in such ranges, heat can be transferred efficiently, and a heat exchange member that can reduce the pressure loss generated by the first fluid while maintaining the heat exchange efficiency. Can do.

  As shown in FIGS. 2A to 2C, the casing 21 of the heat exchanger 30 of this embodiment is a honeycomb that forms the first fluid circulation portion 5 from the first fluid inlet 25 to the first fluid outlet 26. The first fluid circulation part is formed in a straight line so that the structure 1 is fitted, and the second fluid circulation part 6 from the second fluid inlet 22 to the second fluid outlet 23 is also linearly formed. 5 and the second fluid circulation part. The honeycomb structure 1 is provided by being fitted to a casing 21. A second fluid inlet 22 and outlet 23 are formed on opposite sides of the honeycomb structure 1.

  As shown in FIG. 2B, the heat exchanger 30 includes a first fluid circulation part 5 and a second fluid circulation part 6. The first fluid circulation portion 5 is partitioned by a ceramic partition wall 4 and penetrates in the axial direction from one end surface 2 to the other end surface 2, and is formed by a honeycomb structure 1 having a plurality of cells 3 through which the first fluid flows. Is formed. The second fluid circulation portion 6 is formed by the inner peripheral surface 24 of the casing 21 that includes the honeycomb structure 1 and the outer peripheral surface 7 h of the honeycomb structure 1. The casing 21 has an inlet 22 and an outlet 23 for the second fluid. Then, the second fluid flows on the outer peripheral surface 7 h of the honeycomb structure 1 inside the casing 21, thereby exchanging heat with the first fluid.

  When the 1st fluid which distribute | circulates the 1st fluid distribution | circulation part 5 is a heating body, the heat is received through the partition 4, and heat is transmitted to the to-be-heated body which is the 2nd fluid which distribute | circulates. The first fluid and the second fluid are completely separated, and these fluids do not mix.

  In the heat exchanger 30 of the present invention, it is preferable that the first fluid is circulated at a temperature higher than that of the second fluid so as to conduct heat from the first fluid to the second fluid. When gas is circulated as the first fluid and liquid is circulated as the second fluid, heat exchange between the first fluid and the second fluid can be performed efficiently. That is, the heat exchanger 30 of the present invention can be applied as a gas / liquid heat exchanger.

  The heat exchanger 30 of the present invention allows the first fluid having a temperature higher than that of the second fluid to flow through the cells of the honeycomb structure 1 to efficiently heat the heat of the first fluid to the honeycomb structure 1. Can be conducted. That is, the total heat transfer resistance is the thermal resistance from the first fluid to the honeycomb structure 1 + the thermal resistance of the partition walls 4 + the thermal resistance from the honeycomb structure 1 to the second fluid. It is the thermal resistance from the first fluid to the honeycomb structure 1. Since the first fluid passes through the cell 3 in the heat exchanger 30, the contact area between the first fluid and the honeycomb structure 1 is large, and the heat from the first fluid, which is a rate-determining factor, to the honeycomb structure 1 is large. Resistance can be lowered.

  The honeycomb structure 1 is made of ceramics and has a fluid flow path penetrating from one end face 2 in the axial direction to the other end face 2. The outer shape of the honeycomb structure 1 is not limited to a cylindrical shape (columnar shape), but an elliptical cross section perpendicular to the axial (longitudinal) direction, an oval shape in which arcs are combined, a square shape, or other polygonal prism shape. It may be. The honeycomb structure 1 of the embodiment of FIGS. 1A and 1B is formed in a columnar shape.

  In the honeycomb structure 1, a plurality of cells 3 serving as flow paths are defined by partition walls 4, and the shape of a cross section perpendicular to the axial direction of the cells 3 is a circle, an ellipse, a triangle, a quadrangle, and other polygons A desired shape may be appropriately selected from the above.

The cell density of the honeycomb structure 1 (that is, the number of cells per unit cross-sectional area) is not particularly limited, and may be appropriately designed according to the purpose, but is 25 to 2000 cells / in 2 (4 to 320 cells / cm ² ) is preferable. When the cell density is larger than 25 cells / in 2, the strength of the partition walls 4 and the strength of the honeycomb structure 1 itself and the effective GSA (geometric surface area) can be made sufficient. On the other hand, when the cell density is 2000 cells / square inch or less, the pressure loss when the heat medium flows can be reduced.

  Further, the number of cells per honeycomb structure 1 is preferably 1 to 10,000, and particularly preferably 50 to 2000. If the number of cells is too large, the honeycomb itself becomes large, so the heat conduction distance from the first fluid side to the second fluid side becomes long, the heat conduction loss becomes large, and the heat flux becomes small. Further, when the number of cells is small, the heat transfer area on the first fluid side becomes small, the heat resistance on the first fluid side cannot be lowered, and the heat flux becomes small.

  The thickness (wall thickness) of the partition walls 4 of the cells 3 of the honeycomb structure 1 may be appropriately designed according to the purpose, and is not particularly limited. The wall thickness is preferably 50 μm to 2 mm, and more preferably 60 to 800 μm. When the wall thickness is 50 μm or more, the mechanical strength is improved and damage due to impact or thermal stress can be prevented. On the other hand, when the thickness is 2 mm or less, the ratio of the cell volume to the honeycomb structure side increases, so that the pressure loss of the fluid can be reduced.

The density of the partition walls 4 of the cells 3 of the honeycomb structure 1 is preferably 0.5 to ⁵ g / cm ³ . In the case of 0.5 g / cm ³ or more, the strength of the partition wall 4 is sufficient, and the partition wall 4 can be prevented from being damaged by pressure when the first fluid passes through the flow path. Further, if it is 5 g / cm ³ or less, the honeycomb structure 1 itself does not become too heavy, and the weight can be reduced. By setting the density within the above range, the honeycomb structure 1 can be strengthened. Moreover, the effect which improves heat conductivity is also acquired.

  The honeycomb structure 1 preferably has a thermal conductivity of 50 W / m · K or more. More preferably, it is 100-300 W / m * K, More preferably, it is 120-300 W / m * K. By setting it as this range, heat conductivity becomes favorable and the heat in the honeycomb structure 1 can be efficiently discharged to the outside of the metal tube 12.

  The honeycomb structure 1 is preferably made of a ceramic having excellent heat resistance, and particularly preferably contains silicon carbide (SiC) in consideration of heat conductivity. Furthermore, it is preferable that silicon carbide (SiC) is a main component. The main component means that 50% by mass or more of the honeycomb structure 1 is silicon carbide.

  The honeycomb structure 1 is preferably made of a conductive ceramic containing silicon carbide.

  In order to obtain heat exchange efficiency, it is more preferable to use a material containing silicon carbide having high thermal conductivity as the material of the honeycomb structure 1, but in the process of manufacturing the honeycomb structure 1, silicon is impregnated to form a dense body ( (Dense) is more preferable. High heat conductivity can be obtained by using a dense body. For example, in the case of a porous body of silicon carbide, it is about 20 W / m · K, but by making it a dense body, it can be about 150 W / m · K.

As the ceramic material of the honeycomb structure 1, Si-impregnated SiC, (Si + Al) -impregnated SiC, metal composite SiC, Si ₃ N ₄ , and SiC (particularly, a dense material composed only of SiC is preferable). However, it is more desirable to employ Si-impregnated SiC or (Si + Al) -impregnated SiC in order to obtain a dense body for obtaining high heat exchange efficiency. Si-impregnated SiC has a structure in which the SiC particle surface is surrounded by a solidified metal silicon melt and SiC is integrally joined via metal silicon, so that silicon carbide is shielded from the atmosphere containing oxygen and oxidized. It is prevented. Furthermore, SiC has the characteristics of high thermal conductivity and easy heat dissipation, but SiC impregnated with Si is densely formed while exhibiting high thermal conductivity and heat resistance, and has sufficient strength as a heat transfer member. Indicates. That is, the honeycomb structure 1 made of a Si—SiC-based (Si-impregnated SiC, (Si + Al) -impregnated SiC) material has excellent heat resistance, thermal shock resistance, oxidation resistance, and excellent corrosion resistance against acids and alkalis. And high thermal conductivity.

More specifically, the honeycomb structure 1 is made of Si-impregnated SiC composite material, or (Si
+ Al) When the main component is impregnated SiC, if the Si content defined by Si / (Si + SiC) is too small, the bonding material is insufficient, so that bonding between adjacent SiC particles by the Si phase becomes insufficient, and heat Not only does the conductivity decrease, it becomes difficult to obtain a strength that can maintain a thin-walled structure such as a honeycomb structure. Conversely, if the Si content is too high, the honeycomb structure 1 is excessively shrunk by firing due to the presence of metallic silicon more than can appropriately combine the SiC particles, and the porosity decreases. This is not preferable in that adverse effects such as reduction of the average pore diameter occur at the same time. Therefore, the Si content is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass.

  In such Si-impregnated SiC or (Si + Al) -impregnated SiC, the pores are filled with metal silicon, and the porosity may be 0 or close to 0, which is excellent in oxidation resistance and durability, and can be used in a high-temperature atmosphere. Can be used for a long time. Once oxidized, an oxidation protective film is formed, so that no oxidative degradation occurs. Moreover, since it has high strength from room temperature to high temperature, a thin and lightweight structure can be formed. Furthermore, the thermal conductivity is as high as that of copper or aluminum metal, the far-infrared emissivity is also high, and since it is electrically conductive, it is difficult to be charged with static electricity.

  When the first fluid (high temperature side) to be circulated through the heat exchanger 30 of the present invention is exhaust gas, a catalyst is supported on the wall surface inside the cell 3 of the honeycomb structure 1 through which the first fluid (high temperature side) passes. It is preferable that This is because in addition to the role of exhaust gas purification, reaction heat (exothermic reaction) generated during exhaust gas purification can also be exchanged. Catalysts include noble metals (platinum, rhodium, palladium, ruthenium, indium, silver, and gold), aluminum, nickel, zirconium, titanium, cerium, cobalt, manganese, zinc, copper, tin, iron, niobium, magnesium, lanthanum, It is preferable to contain at least one element selected from the group consisting of samarium, bismuth and barium. These may be metals, oxides, and other compounds.

  The supported amount of the catalyst (catalyst metal + support) supported by the first fluid circulation portion 5 of the honeycomb structure 1 through which the first fluid (high temperature side) passes is preferably 10 to 400 g / L. In the case of a noble metal, it is more preferably 0.1 to 5 g / L. When the loading amount of the catalyst (catalyst metal + support) is 10 g / L or more, the catalytic action is sufficiently exhibited. On the other hand, by setting it as 400 g / L or less, it can prevent that a pressure loss becomes large, and can prevent that manufacturing cost rises.

  When the catalyst is supported, the honeycomb structure 1 is masked so that the catalyst is supported on the honeycomb structure 1. In advance, an aqueous solution containing a catalyst component is impregnated into ceramic powder as carrier fine particles, and then dried and fired to obtain catalyst-coated fine particles. A dispersion liquid (water, etc.) and other additives are added to the catalyst-coated fine particles to prepare a coating liquid (slurry). The slurry is coated on the partition walls 4 of the honeycomb structure 1, and then dried and fired. The catalyst is supported on the partition walls 4 of the cells 3 of the honeycomb structure 1. When firing, the masking of the honeycomb structure 1 is peeled off.

  The first fluid to be circulated in the heat exchanger 30 of the present invention having the above configuration is preferably a heating body, and the heating body is particularly limited to a gas, a liquid, etc., as long as it is a medium having heat. Not. For example, if it is gas, the exhaust gas of a motor vehicle etc. are mentioned. In addition, the medium to be heated, which is the second fluid that takes heat from the heating body (exchanges heat), is not particularly limited as a medium, as long as the temperature is lower than that of the heating body. Since at least one of the partition walls 4 and the outer peripheral wall 7 is formed as a dense material, the second fluid is preferably a liquid, and water is preferable in consideration of handling, but is not particularly limited to water.

  As described above, since the honeycomb structure 1 has high thermal conductivity and there are a plurality of portions that become flow paths by the partition walls 4, high heat exchange efficiency can be obtained. For this reason, the whole honeycomb structure 1 can be reduced in size and can be mounted on a vehicle.

(Production method)
Next, a method for manufacturing the honeycomb structure 1 used as the heat exchange member 10 of the present invention will be described. First, a honeycomb forming material is formed by extruding a ceramic forming raw material, and partitioned by ceramic partition walls 4 and penetrating in an axial direction from one end face 2 to the other end face 2 to form a plurality of cells 3 serving as fluid flow paths. Shape the body.

  Specifically, it can be produced as follows. A honeycomb structure 1 in which a plurality of cells 3 serving as gas flow paths are partitioned by partition walls 4 is formed by extruding a clay containing ceramic powder into a desired shape to form a honeycomb formed body, and then drying and firing. Get.

  As the material of the honeycomb structure 1, the above-described ceramics can be used. For example, when manufacturing a honeycomb structure mainly composed of a Si-impregnated SiC composite material, first, a predetermined amount of C powder, SiC powder, A binder, water or an organic solvent is kneaded and molded to obtain a molded body having a desired shape. Next, the compact is placed in a reduced pressure inert gas or vacuum under a metal Si atmosphere, and the compact is impregnated with metal Si.

Even when Si ₃ N ₄ , SiC, or the like is adopted, the molding raw material is converted into clay, and the clay is extruded in the molding process, thereby forming a plurality of exhaust gas flow paths partitioned by the partition walls 4. A honeycomb-shaped formed body having the cells 3 can be formed. The honeycomb structure 1 can be obtained by drying and firing this (see FIG. 1A and the like). And the heat exchanger 30 is producible by accommodating the honeycomb structure 1 in the casing 21 (refer FIG. 2A etc.).

  In the present invention, basically, extrusion molding can be used as it is, and man-hours can be greatly reduced. Further, when an attempt is made to produce the same structure with a refractory metal, steps such as press working and welding are necessary, but are not necessary in the present invention. Therefore, the manufacturing cost can be reduced and sufficient heat exchange efficiency can be obtained.

(Embodiment 2)
FIG. 3A shows a perspective view of another embodiment of the heat exchange member 10. 3B is a cross-sectional view cut along a cross section parallel to the axial direction, and FIG. 3C is a view of the heat exchange member 10 as viewed from one end face in the axial direction. The heat exchange member 10 of the present embodiment includes a honeycomb structure 1, a metal tube 12 on the outer peripheral side of the honeycomb structure 1, and an intermediate material 13 sandwiched between the honeycomb structure 1 and the metal tube 12. Prepare. The intermediate material 13 is made of a material having at least a part having a Young's modulus of 150 GPa or less. Then, the first fluid is circulated inside the honeycomb structure 1 and the second fluid having a temperature lower than that of the first fluid is circulated on the outer peripheral surface 12h side of the metal tube 12, whereby the heat exchange member 10 is The heat exchange between the first fluid and the second fluid can be performed. Since the heat exchange member 10 includes the metal pipe 12 on the outer peripheral side of the honeycomb structure 1, the first fluid and the second fluid are completely separated, and these fluids are not mixed. Moreover, since the heat exchange member 10 is provided with the metal tube 12, it is easy to process it according to an installation place and an installation method, and its freedom is high. The heat exchange member 10 can protect the honeycomb structure 1 by the metal tube 12 and is resistant to external impact.

  By using the intermediate material 13 made of a material having a Young's modulus of 150 GPa or less for the heat exchange member 10, the adhesion between the metal tube 12 and the honeycomb structure 1 can be improved and the thermal conductivity can be improved. In this case, it is preferable that the intermediate material 13 is in contact with at least a part of the metal tube 12 and the honeycomb structure 1 in order to improve the thermal conductivity of the heat exchange member 10.

  Furthermore, it is preferable that the intermediate material 13 has a thermal conductivity of at least a part of 1 W / m · K or more. When the heat conductivity of the intermediate material 13 is 1 W / m · K or more, the heat conductivity of the heat exchange member 10 can be improved.

  Examples of the intermediate material 13 include a graphite sheet, a metal sheet, a gel sheet, and an elastoplastic fluid. Examples of the metal constituting the metal sheet include gold (Au), silver (Ag), copper (Cu), and aluminum (Al). An elasto-plastic fluid is a material that, if it is a small force, behaves as a solid without plastic deformation (has an elastic modulus), and deforms freely like a fluid when a large force is applied. Etc. are mentioned as examples. In view of adhesion, thermal conductivity, etc., it is preferable to use a graphite sheet as the intermediate material 13. Hereinafter, a graphite sheet will be described as an example of the intermediate material 13.

  The metal tube 12 and the honeycomb structure 1 can be fitted by, for example, shrink fitting with the intermediate material 13 made of a graphite sheet sandwiched (first integration method described later). By sandwich-fitting the intermediate material 13 made of a graphite sheet, pressure is applied to the graphite sheet in an environment of room temperature to 150 ° C. when the joint portion between the metal tube 12 and the honeycomb structure 1 is used, and heat is applied. Can communicate.

  The graphite sheet in the present specification is a sheet obtained by rolling a graphite mainly composed of expanded graphite into a sheet, or a sheet obtained by pyrolyzing a polymer film. Including what is called. The graphite sheet preferably has a Young's modulus in the thickness direction of 1 GPa or less and a thermal conductivity in the thickness direction of 1 W / m · K or more. The thermal conductivity in the thickness direction is more preferably 3 to 10 W / m · K. In addition, the thermal conductivity in the in-plane direction is preferably 5 to 1600 W / m · K, and more preferably 100 to 400 W / m · K.

  The Young's modulus of the graphite sheet is preferably 1 MPa to 1 GPa. More preferably, it is 5-500 MPa, More preferably, it is 10-200 MPa. If the Young's modulus is 1 MPa or more, the density of graphite is sufficient and the thermal conductivity is good. On the other hand, when the pressure is 500 MPa or less, even a thin graphite sheet is sufficiently elastically deformed at the time of shrink fitting, and adhesion and stress relaxation effect of the metal tube 12 are obtained.

  The thickness of the graphite sheet is preferably 25 μm to 1 mm, more preferably 25 to 500 μm, and still more preferably 50 to 250 μm. Graphite sheets become more expensive as they become thinner. Moreover, when it becomes thick, heat resistance will be produced. By using the graphite sheet in this range, the thermal conductivity becomes good, and the heat in the honeycomb structure 1 can be efficiently discharged to the outside of the metal tube 12.

As the metal tube 12, one having heat resistance and corrosion resistance is preferable. For example, a SUS tube, a copper tube, a brass tube, or the like can be used. The temperature of the cooling water, which is the second fluid flowing on the outer peripheral surface 12h of the metal tube 12, can rise to around 120 ° C., but at this time, due to the difference in thermal expansion coefficient, the honeycomb structure 1 and the metal tube 12 It is preferable to set the diameter of the metal tube 12 within the range of the following formula so that the pressure between them does not escape. That is, the outside diameter of the honeycomb structure 1 at room temperature of 25 ° C. is d, the thickness of the graphite sheet is c, the thermal expansion coefficient of the honeycomb structure 1 is α, the thermal expansion coefficient of the metal tube 12 is β, and the shrink fitting temperature is Assuming 1000 ° C., the inner diameter D of the metal tube 12 is
d + 2 * c-975 * [beta] * d <D <d + 2 * c-125 * ([beta]-[alpha]) * d
It is preferable to set so that.

The inner diameter D of the metal tube 12 is within a range in which an interference fit pressure is reliably applied in a temperature range from room temperature to 150 ° C. assumed at the joint between the honeycomb structure 1 and the metal tube 12. By setting the inner diameter D of the metal tube 12 within this range, it is possible to prevent a tensile stress from remaining in the metal tube 12 more than necessary. Specifically, for example, the outer diameter of the honeycomb structure 1 is 42 mm, the thermal expansion coefficient α of the honeycomb structure 1 is 4.0 × 10 ⁻⁶ , and the thermal expansion coefficient β of the metal tube 12 is 17 × 10 ⁻⁶ . When the thickness c of the graphite sheet is 0.2 mm, 41.704 mm <D <42.332 mm.

(Production method)
A method for manufacturing the heat exchange member 10 (see FIG. 3A and the like) including the metal tube 12 on the outer peripheral side of the honeycomb structure 1 will be described. First, the honeycomb structure 1 is manufactured in the same manner as in the first embodiment.

  Next, the honeycomb structure 1, the intermediate material 13, and the metal tube 12 manufactured as described above are integrated. In the first method, first, a graphite sheet used as the intermediate member 13 is wound around the outer peripheral surface 7 h of the outer peripheral wall 7 of the honeycomb structure 1. At this time, you may stick using an adhesive agent. By using an adhesive, a graphite sheet can be uniformly attached. It is desirable that the adhesive is sufficiently thin and has good heat conductivity. In addition, after shrink-fitting, an interference-fitted state is obtained, so that the adhesion may be a full adhesion or a partial adhesion. Subsequently, the metal tube 12 is heated to about 1000 ° C. with a high-frequency heater. Then, the honeycomb structure 1 can be inserted into the metal tube 12 and integrated by shrink fitting to form the heat exchange member 10.

  A second method of integrating the honeycomb structure 1, the intermediate material 13, and the metal tube 12 is a metal tube 12 using a metal plate (flat plate). First, a graphite sheet is wound around the outer peripheral surface 7 h of the outer peripheral wall 7 of the honeycomb structure 1. Next, the honeycomb structure 1 is wound and tightened while applying a metal plate (flat plate) to the honeycomb structure 1. Then, the end portions 12 a of the metal plate wound around the honeycomb structure 1 and formed into a cylindrical shape are joined to form a metal tube 12. For example, laser welding can be used as the joining between the end portions 12a of the metal plates.

  A third method of integrating the honeycomb structure 1, the intermediate material 13, and the metal tube 12 is a hot plastic working method. First, a graphite sheet is wound around the outer peripheral surface 7 h of the outer peripheral wall 7 of the honeycomb structure 1. Next, the honeycomb structure 1 is installed inside the metal tube 12. The inner diameter of the metal tube 12 is sufficiently larger than the outer diameter of the honeycomb structure 1. Subsequently, the region of the metal pipe 12 where the honeycomb structure 1 is installed is heated to about 400 to 1100 ° C. using a high-frequency heating device or the like. The metal tube 12 is reduced in diameter by pulling both ends of the metal tube while locally heating the metal tube 12. The heat exchange member 10 can be formed by cooling after the metal tube 12 and the honeycomb structure 1 are integrated.

  As shown in FIG. 4, the heat exchanger 30 can be manufactured by housing the honeycomb structure 1 including the metal pipe 12 in the casing 21. The cells 3 of the honeycomb structure 1 become the first fluid circulation part 5 through which the first fluid flows. The heat exchanger 30 is configured such that a first fluid having a temperature higher than that of the second fluid flows in the cells 3 of the honeycomb structure 1. In addition, an inlet 22 and an outlet 23 for the second fluid are formed in the casing 21, and the second fluid circulates on the outer peripheral surface 12 h of the metal tube 12 of the heat exchange member 10.

  The heat exchange member 10 of the present invention is provided with an intermediate material 13 made of a graphite sheet or the like having a low Young's modulus between the honeycomb structure 1 and the metal tube 12 on the outer peripheral side thereof, thereby improving adhesion. For this reason, the thermal conductivity in the thickness direction (the radial direction of the tube) can be 3 W / m · K or more, and the thermal conductivity is good. Further, the thermal conductivity in the longitudinal (axial) direction can be 250 W / m · K or more, and the thermal conductivity is also good. Since a side slip is possible with a graphite sheet or the like, stress due to a difference in thermal expansion between the honeycomb structure 1 and the metal tube 12 is hardly generated. For this reason, thermal durability is sufficient practically.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

(Examples 1-8, Comparative Examples 1-5)
The heat exchanger 30 in which the first fluid circulation part and the second fluid circulation part were formed by the honeycomb structure 1 and the casing 21 was produced as follows.

(Manufacture of honeycomb structure)
A honeycomb structure 1 made of silicon carbide was manufactured by extruding a clay containing ceramic powder into a desired shape, followed by drying and firing. The honeycomb structure 1 had a circle equivalent diameter Φ, which is the diameter of a circle having the same area as the area of the heat collecting portion, of 40 mm, and the total length L [mm] in the axial direction of the honeycomb structure 1 was 100 mm. . Table 1 shows the thermal conductivity λ [W / K · m] of the material of the partition walls 4, the wall thickness t [mm] of the partition walls 4, and the cell density ρ [pieces / square inch].

(casing)
As an outer container of the honeycomb structure 1, a casing 21 made of stainless steel was used. In Examples 1 to 8, one honeycomb structure 1 was disposed in the casing 21 (see FIGS. 1A and 2C). The first fluid circulation part 5 is formed in a honeycomb structure, and the second fluid circulation part 6 is formed so as to circulate (outside structure) the outer periphery of the honeycomb structure 1 in the casing 21. In addition, piping for introducing and discharging the first fluid to the honeycomb structure 1 and the second fluid to the casing 21 was attached to the casing 21. Note that these two paths are completely isolated so that the first fluid and the second fluid do not mix (peripheral flow structure). Moreover, all the external structures of the honeycomb structures 1 of Examples 1 to 8 were the same. In FIG. 2C, the distance L3 between the outer peripheral surface 7h of the honeycomb structure 1 and the inner peripheral surface 24 of the casing 21 is 1 mm.

(First fluid and second fluid)
The inlet temperature and flow rate of the first fluid and the second fluid to the honeycomb structure 1 were all the same. As the first fluid, nitrogen gas (N ₂ ) at 500 ° C. was used. Moreover, water was used as the second fluid.

(Test method)
Nitrogen gas was passed through the first fluid circulation part 5 of the honeycomb structure 1, and (cooling) water was allowed to flow through the second fluid circulation part 6 in the casing 21. The flow rate of nitrogen gas with respect to the honeycomb structure 1 was 6 L / s. The flow rate of (cooling) water was 15 L / min. The test conditions such as the flow rates of the first fluid and the second fluid were all the same. In Example 1, a pipe having a second fluid flow path is provided on the outer periphery of a pipe serving as a first fluid flow path (see FIG. 2B). The (cooling) water was configured to flow outside the pipe (the gap (L3) was 1 mm) (see FIG. 2C). Pressure gauges were arranged in the first fluid passage pipes at the front and rear stages of the honeycomb structure 1, and the pressure loss of the honeycomb structure 1 was specified from the pressure difference.

(Test results)
Table 1 shows heat exchange efficiency, pressure loss (pressure loss), and heat exchange efficiency / pressure loss. The heat exchange efficiency (%) is calculated by calculating the amount of energy from ΔT ° C. (exit temperature of the honeycomb structure 1 -inlet temperature) of the first fluid (nitrogen gas) and the second fluid (water), respectively. Calculated with
(Equation 1) Heat exchange efficiency (%) = (first fluid (gas) inlet temperature−second fluid (cooling water) outlet temperature) / (first fluid (gas) inlet temperature−first Fluid (gas) outlet temperature) x 100

  Table 1 shows the total length of the honeycomb structure 1 (L = 100 mm), the thermal conductivity (100 [W / K · m]) of the material of the honeycomb partition walls 4, and the cell structure (wall thickness t of the cell partition walls 4). The heat exchange efficiency and the pressure loss when the cell density ρ) is changed are shown. It is preferable that the amount of heat recovered necessary for improving fuel consumption, such as shortening the warm-up time of the engine, be larger, and the pressure loss (pressure loss) of the heat exchange member that has less influence on the engine output be smaller. The improvement in heat exchange efficiency and the suppression of increase in pressure loss are opposite in directionality, so that the heat exchange efficiency per unit pressure loss value is preferably high as the performance of the heat exchange member. When the heat exchange efficiency / pressure loss was 85 or more, the heat could be effectively utilized while suppressing the increase in pressure loss. In order to satisfy this, it was necessary that 1000 / λ ≦ t × ρ ≦ 80. That is, when t × ρ is not within this range, the heat exchange efficiency / pressure loss is less than 85, and the heat recovery amount cannot be improved without increasing the pressure loss. By setting t × ρ within this range, the heat exchange efficiency per unit pressure loss can be optimized.

  The heat exchanger of the present invention is not particularly limited even in the automotive field and the industrial field as long as it is used for heat exchange between the heating body (high temperature side) and the heated body (low temperature side). When used for exhaust heat recovery from exhaust gas in the automobile field, it can be used to improve the fuel efficiency of automobiles.

1: honeycomb structure, 2: end face, 3: cell, 4: partition, 5: first fluid circulation part, 6: second fluid circulation part, 7: outer peripheral wall, 7h: outer peripheral surface, 10: heat exchange member, 12: metal pipe, 12a: end, 12h: outer peripheral surface, 13: intermediate material, 21: casing, 22: inlet, 23: outlet, 24: inner peripheral surface, 25: inlet, 26: outlet, 30: heat exchange vessel.

Claims (10)

Formed as a honeycomb structure having a plurality of cells partitioned by ceramic partition walls and penetrating in the axial direction from one end face to the other end face and serving as a first fluid circulation section through which a heating body as a first fluid circulates And
The first fluid that flows through the first fluid circulation portion and the second fluid that exchanges heat with the first fluid by flowing on the outer peripheral surface of the outer peripheral wall of the honeycomb structure do not mix. As described above, at least one of the partition walls and the outer peripheral wall of the honeycomb structure is made dense,
The thermal conductivity of the partition wall material of the honeycomb structure is λ [W / K · m], the cell wall thickness of the honeycomb structure is t [mm], and the cell density is ρ [pieces / Square inch]
1000 / λ ≦ t × ρ ≦ 80
A heat exchange member.   The heat exchange member according to claim 1, wherein t> 0.2 and ρ ≦ 100.   The heat exchange member according to claim 1, wherein t ≦ 0.2 and ρ> 100. When the equivalent circle diameter of the cross-sectional area of the cross section perpendicular to the axial direction of the honeycomb structure is Φ [mm], and the total length of the axial length of the honeycomb structure is L [mm]
The heat exchange member according to claim 1, wherein 15 ≦ Φ ≦ 120 and 0.05 ≦ L / Φ ≦ 10.   A metal pipe is provided on the outer peripheral side of the honeycomb structure, the first fluid is circulated inside the honeycomb structure, the second fluid is circulated on the outer peripheral surface side of the metal pipe, and the first fluid and The heat exchange member according to any one of claims 1 to 4, wherein heat exchange with the second fluid is performed.   The heat exchange member according to claim 5, further comprising an intermediate member sandwiched between the honeycomb structure and the metal tube.   The heat exchange member according to claim 6, wherein the intermediate material is made of a graphite sheet.   The heat exchange member according to any one of claims 1 to 7, wherein the honeycomb structure has a thermal conductivity of 100 W / m · K or more.   The heat exchange member according to any one of claims 1 to 8, wherein the honeycomb structure is mainly composed of silicon carbide. A heat exchanging member according to any one of claims 1 to 9, an inlet and an outlet for the second fluid are formed, and a casing including the honeycomb structure therein.
The inside of the casing serves as a second fluid circulation part, and the second fluid circulates on the outer peripheral surface of the honeycomb structure in the second fluid circulation part, thereby receiving heat from the first fluid. Exchanger.

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