JP2012037165A - Heat exchange member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchange member having durability against thermal shock that exchanges heat between two fluids, at least one of which is a liquid.SOLUTION: The heat exchange member 11 includes a heat collecting part 12 and a blocking part 13. The heat collecting part 12 is formed as a honeycomb structure having a plurality of cells partitioned by SiC partitioning walls in which a first fluid which is a heating element flows. The blocking part 13 is formed as an outer peripheral wall 7 which is disposed on the outer periphery of the heat collecting part 12, which has an SiC outer peripheral wall 7a formed of SiC, and which has a dense part that is dense, structured by a material in which at least one portion thereof includes a metal and is different from that of the heat collecting part 12, and blocks the flow of fluid. The heat exchange member 11 exchanges heat between the first fluid and a second fluid through the blocking part 13 by making the first fluid flow in the cells 3 and making the second fluid lower in temperature than the first fluid flow on an outer peripheral face 7h side of the blocking part 13.

Description

  The present invention relates to a heat exchange member that performs heat exchange between a first fluid and at least one of which is a liquid.

  By exchanging heat from a high temperature fluid to a low temperature fluid, heat can be effectively utilized. For example, there is a demand for technology for recovering heat from a high-temperature gas such as combustion exhaust gas from an engine. 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 weight, and low heat conduction.

  Patent Document 1 discloses a high-temperature heat exchanger for a honeycomb structure made of a porous silicon carbide sintered body that exchanges heat between a fluid flowing inside and a fluid existing outside. . A paste composed mainly of silicon carbide fine powder is applied to the outer wall portion of the honeycomb structure made of silicon carbide and fired to coat the outer wall portion with a layer made of a dense substance, and liquid leakage from the outer wall portion Is preventing. Since the honeycomb structure and the paste applied to the outer wall portion are made of silicon carbide, the honeycomb structure (molded body) and the paste are fired in the same firing process, so that no special process is required. Patent Document 2 describes a technique for recovering heat by integrating a ceramic honeycomb structure and a single metal.

JP-A-6-345555 JP-A-9-327627

  However, Patent Document 1 is vulnerable to thermal shock because the outer peripheral wall is formed of a dense layer of silicon carbide. For this reason, the heat exchange member which further improved the durability with respect to heat is calculated | required. Since the ceramic honeycomb structure used in Patent Document 2 does not have an outer peripheral wall structure, it needs to be stamped and integrated with an outer metal.

  An object of the present invention is to provide a heat exchange member having durability against thermal shock for heat exchange of two fluids, at least one of which is a liquid.

  The present inventors have found that the above problem can be solved by adopting a configuration in which the heat exchange member includes metal in at least a part of the blocking portion of the outer peripheral wall. That is, according to the present invention, the following heat exchange member is provided.

[1] A heat collecting section formed as a honeycomb structure having a plurality of cells through which a first fluid as a heating body, which is partitioned by SiC partition walls, is disposed on an outer periphery of the heat collecting section, It is formed as an outer peripheral wall having an SiC outer peripheral wall made of SiC, and having a dense dense portion made of a material different from the heat collecting portion, at least part of which contains metal, and allows fluid flow. And a second fluid having a temperature lower than that of the first fluid is circulated on the outer peripheral surface side of the intercepting portion, at least one of which is a liquid and the second fluid A heat exchange member that performs heat exchange between the first fluid and the second fluid via the blocking part in a state where the fluid is separated by the blocking part.

[2] The porosity difference between the heat collecting part and the blocking part is 10% or more, and the metal content difference between the heat collecting part and the part including the metal of the blocking part is 10% or more. The heat exchange member according to [1].

[3] The heat exchange member according to claim 1 or 2, wherein the blocking portion includes more metal on the outer peripheral surface side than on the inner peripheral surface side.

[4] The heat exchanging member according to any one of [1] to [3], wherein the blocking unit includes one or more metal layers.

[5] The [1] to [1], wherein the blocking part is configured by an SiC outer peripheral wall integrally formed with SiC and the heat collecting part, and a metal body provided on an outer peripheral surface of the SiC outer peripheral wall. [3] The heat exchange member according to any one of [3].

[6] The surface roughness Ra of the outer peripheral surface, which is the surface of the SiC outer peripheral wall facing the metal body, is 0.5 μm or more, and the outer peripheral surface has an axial direction in which the first fluid flows. The heat exchange member according to [5], wherein a streak-like line portion extending in the shape is formed.

[7] The heat exchange member according to any one of [1] to [6], wherein the blocking portion has a porosity of the outer peripheral wall excluding metal of 10% or more.

  By configuring the outer peripheral wall, which is the blocking portion of the heat exchange member, to include metal, the blocking portion and the heat collecting portion are made of different materials, and heat resistance can be improved. Thereby, generation | occurrence | production of the crack of a heat exchange member can be prevented.

It is a figure which shows one end surface of the axial direction of the heat exchange member of this invention. It is a partial enlarged view of one end surface of the axial direction of the heat exchange member of the present invention, and is a view showing an embodiment in which metal is impregnated on the outer peripheral surface side of the outer peripheral wall constituting the blocking portion. It is a schematic diagram which shows one Embodiment of the heat exchanger containing the heat exchange member of this invention. It is a partial enlarged view of one end surface of the axial direction of the heat exchange member of the present invention, and is a diagram showing an embodiment in which a metal is provided on the outer peripheral surface of the outer peripheral wall constituting the blocking portion. It is a figure which shows embodiment by which the filament part was formed in the outer peripheral surface of a honeycomb structure. It is a perspective view which shows the honeycomb structure which has an extended outer peripheral wall. It is sectional drawing which cut | disconnected by the cross section parallel to an axial direction which shows the honeycomb structure which has an extended outer peripheral wall. It is a perspective view showing an embodiment of a heat exchanger in which a honeycomb structure having an extended outer peripheral wall is accommodated in a casing. It is sectional drawing cut | disconnected in the cross section parallel to an axial direction which shows embodiment of the heat exchanger in which the honeycomb structure which has an outer peripheral wall extended in a casing was accommodated. It is sectional drawing which cut | disconnected in the cross section parallel to an axial direction which shows embodiment of the heat exchanger with which a casing is provided with a cylindrical part and an outer casing part integrally. It is sectional drawing cut | disconnected by the cross section perpendicular | vertical to an axial direction which shows embodiment of the heat exchanger in which the honeycomb structure which has an outer peripheral wall extended in a casing was accommodated. FIG. 5 is a perspective view showing another embodiment of a heat exchanger in which a honeycomb structure having an extended outer peripheral wall is accommodated in a casing. FIG. 6 is a cross-sectional view taken along a cross section parallel to the axial direction, showing another embodiment of a heat exchanger in which a honeycomb structure having an extended outer peripheral wall is accommodated in a casing. FIG. 6 is a cross-sectional view taken along a cross section perpendicular to the axial direction, showing another embodiment of a heat exchanger in which a honeycomb structure having an extended outer peripheral wall is accommodated in a casing. It is a schematic diagram which shows one Embodiment of the heat exchanger of this invention cut | disconnected by the cross section perpendicular | vertical to an axial direction. It is a perspective view which shows one Embodiment of the heat exchanger of this invention which heat-exchanges a 1st fluid and a 2nd fluid by a counterflow. It is a schematic diagram for demonstrating the space | interval of a honeycomb structure and a casing.

  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.

  FIG. 1A shows one end face in the axial direction of the heat exchange member 11 of the present invention. FIG. 1B shows a partially enlarged view of the end face. As shown in FIGS. 1A and 1B, the heat exchange member 11 is partitioned by a SiC partition wall 4 and penetrates from one end surface 2 to the other end surface 2 in the axial direction, and a heating body as the first fluid flows. The honeycomb structure 1 having a plurality of cells 3 is formed. The heat exchange member 11 of the present invention includes a heat collecting part 12 and a blocking part 13. The heat collecting section 12 is formed as a honeycomb structure having a plurality of cells 3 which are partitioned by SiC partition walls and through which a first fluid as a heating body flows. The shielding unit 13 is disposed on the outer periphery of the heat collecting unit 12, has a SiC outer peripheral wall 7 a formed of SiC, and at least a part thereof includes a metal and is formed of a material different from that of the heat collecting unit 12. It is formed as an outer peripheral wall 7 having a quality dense part, and blocks the flow of fluid.

  FIG. 1C shows a perspective view of a heat exchanger 30 including the heat exchange member 11 of the present invention. As shown in FIG. 1C, the heat exchanger 30 is formed by a heat exchange member 11 (honeycomb structure 1) and a casing 21 that includes the heat exchange member 11 therein. The cells 3 of the honeycomb structure 1 of the heat exchange member 11 serve as 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 7 h of the honeycomb structure 1. That is, the second fluid circulation portion 6 for receiving heat from the first fluid is formed by the outer peripheral surface 7 h of the honeycomb structure 1 of the heat exchange member 11 and the inner peripheral surface of the casing 21. That is, the heat exchange member 11 circulates a second fluid having a temperature lower than that of the first fluid on the outer peripheral surface 7h side of the blocking portion 13, and at least one of the first fluid and the second fluid that are liquids. Heat exchange between the first fluid and the second fluid is performed via the blocking unit 13 while being separated by the blocking unit 13. 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.

  The honeycomb structure 1 is preferably made of ceramics having excellent heat resistance. In particular, in consideration of heat conductivity, the heat collecting part 12 is preferably SiC (silicon carbide), and the blocking part 13 partially includes SiC. It is preferable to have a dense part formed of a material (metal and SiC) different from that of the heat collecting part 12 and having a SiC outer peripheral wall 7a and a metal in part.

  However, it is not always necessary that the entire honeycomb structure 1 is made of SiC (silicon carbide), and it is sufficient that SiC (silicon carbide) is contained in the main body. That is, the honeycomb structure 1 is preferably made of ceramics containing SiC (silicon carbide). As the physical properties of the honeycomb structure 1, the thermal conductivity at room temperature is preferably 10 W / mK or more and 300 W / mK or less, but is not limited thereto. Instead of ceramics, a corrosion-resistant metal material such as Fe-Cr-Al alloy can be used.

  In order for the heat exchanger 30 of the present invention to obtain a high heat exchange rate, it is more preferable to use a material of the honeycomb structure 1 containing SiC (silicon carbide) having high thermal conductivity. However, even in the case of SiC (silicon carbide), a high thermal conductivity cannot be obtained in the case of a porous body. Therefore, silicon may be impregnated in the manufacturing process of the honeycomb structure 1 to form a dense body structure. High heat conductivity can be obtained by using a dense structure. For example, in the case of a porous body of SiC (silicon carbide), it is about 20 W / mK, but by making it a dense body, it can be about 150 W / mK.

That is, Si-impregnated SiC, (Si + Al) -impregnated SiC, metal composite SiC, Si ₃ N ₄ , SiC, or the like can be used as the ceramic material, but in order to obtain a dense structure for obtaining a high heat exchange rate. Alternatively, Si-impregnated SiC or (Si + Al) -impregnated SiC may be employed. Si-impregnated SiC has a structure in which the SiC particle surface is surrounded by solidified metal-silicon melt and SiC is integrally bonded via metal silicon, so that silicon carbide is shielded from an oxygen-containing atmosphere and prevented from oxidation. Is done. 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, when the honeycomb structure 1 is mainly composed of a Si-impregnated SiC composite material or (Si + Al) -impregnated SiC, if the Si content defined by Si / (Si + SiC) is too small, the bonding material is formed. Due to the shortage, the bonding between adjacent SiC particles due to the Si phase becomes insufficient, and not only the thermal conductivity is lowered, but it is difficult to obtain a strength capable of maintaining a thin-walled structure such as a honeycomb structure. Become. 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.

  For example, as shown in FIG. 1B, the blocking portion 13 impregnates the silicon carbide outer peripheral wall 7 (SiC outer peripheral wall 7a) with a metal to form a dense dense portion, or as shown in FIG. It is preferable to provide a metal on the outer peripheral surface 7h of the SiC outer peripheral wall 7a. As shown in FIG. 1B, in the embodiment in which the outer peripheral wall 7 is impregnated with metal, the metal impregnated layer 7i is formed by impregnating the outer peripheral surface 7h and the vicinity of the outer peripheral wall 7 with the metal to form a dense portion. Alternatively, the metal may be inclined and distributed in the outer peripheral wall 7. In the case of impregnating the metal, after the extrusion molding, the honeycomb structure 1 is impregnated by placing the metal and performing a heat treatment.

  As shown in FIG. 1D, the blocking portion is configured by a SiC outer peripheral wall 7a formed integrally with the heat collecting portion 12 by SiC, and a metal body provided on the outer peripheral surface 7h of the SiC outer peripheral wall 7a. It can be constituted as follows. As shown in FIG. 1D, the provision of metal means that a metal body such as a metal plate 7j may be fitted to the outer peripheral surface 7h, or may be wound. As shown in FIG. 1D, when a metal body such as a metal plate 7j is provided on the outer peripheral surface of the SiC outer peripheral wall 7a of the honeycomb structure 1, the SiC outer peripheral wall 7a and the metal plate 7j of the honeycomb structure 1 are connected to the outer peripheral wall 7j. And a blocking portion 13. In both cases of FIG. 1B and FIG. 1D, a part of the outer peripheral wall 7 that is the blocking portion 13 is configured to contain SiC (that is, has the SiC outer peripheral wall 7 a), and on the outer peripheral surface side of the blocking portion 13. It is preferable that more metal is contained than on the inner peripheral surface side. If comprised in this way, since SiC has large heat conduction, it becomes easy for the SiC outer peripheral wall 7a to collect heat from the heat collecting part 12, and it becomes easy to transmit heat to the outer peripheral side. Therefore, a high heat exchange rate can be expected. Moreover, since it has the dense part containing a metal, intensity | strength can also be improved. Examples of the metal include Si + Al in the case of FIG. 1B and stainless steel, aluminum, copper, and the like in the case of FIG. 1D.

  As shown in FIG. 1D, when a metal body such as a metal plate 7j is provided on the outer peripheral surface of the SiC outer peripheral wall 7a of the honeycomb structure 1, the surface of the SiC outer peripheral wall 7a faces the metal body (metal plate 7j). The surface roughness Ra of the outer peripheral surface 7h is 0.5 μm or more (reference length 10 mm). As shown in FIG. 1E, the outer peripheral surface 7h of the honeycomb structure 1 has an axial direction in which the first fluid flows. It is preferable that the streak-like linear portion 7m extending in the direction is formed. More preferably, the surface roughness Ra of the outer peripheral surface 7h is 1.0 μm or more and 10 μm or less, and more preferably, the surface roughness Ra of the outer peripheral surface 7h is 3.0 μm or more and 10 μm or less. Thereby, the adhesiveness of the outer peripheral surface 1 of the honeycomb structure 1 and the metal plate 7j can be improved.

  The heat exchange member 11 has a porosity difference of 10% or more between the heat collecting portion 12 and the blocking portion 13, and a metal content difference between the heat collecting portion 12 and the portion containing the metal of the blocking portion 13 is 10%. % Or more is preferable. The porosity difference is more preferably 10% or more and 60% or less, and further preferably 10% or more and 40% or less. The metal content difference is more preferably 10% or more and 60% or less, and further preferably 10% or more and 40% or less. In addition, the porosity of the shielding part 13 is the porosity of the dense part including the most metal, and the metal content rate of the part including the metal of the shielding part 13 is the density of the dense part including the metal most. It is a metal content rate. That is, the porosity difference between the heat collecting part 12 and the blocking part 13 is the porosity difference between the heat collecting part 12 and the most dense part of the blocking part 13. When impregnated with metal, it is the most dense part (porosity minimum) regardless of whether the distribution of the metal is inclined in the blocking part 13, and when the metal is wound, the metal part It is.

  The blocking unit 13 is preferably configured to include one or more metal layers. That is, it is preferable that the blocking portion 13 has a metal multilayer structure. Here, the multilayer structure includes, for example, (1) an impregnated metal layer, (2) a metal layer for relaxing thermal stress, and (3) a metal three-layer structure in contact with the second fluid. it can. Other embodiments include (1) a metal layer for relieving thermal stress and (2) a two-layer metal structure in contact with the second fluid. When the metal layer has a multilayer structure, a difference in thermal expansion generated in each layer can be absorbed, and thermal stress can be reduced.

  The blocking part 13 preferably has a porosity of the outer peripheral wall excluding metal of 10% or more. If it is less than 10%, molding is very difficult. More preferably, it is 60% or less in order to make the strength sufficient. The porosity of the outer peripheral wall excluding the metal is more preferably 10% or more and 60% or less, and further preferably 10% or more and 40% or less.

  When the first fluid (high temperature side) to be circulated through the heat exchanger 30 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. 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. Noble metals (platinum, rhodium, palladium, ruthenium, indium, silver, and gold), aluminum, nickel, zirconium, titanium, cerium, cobalt, manganese, zinc, copper, zinc, tin, iron, niobium, magnesium, lanthanum, samarium, It is preferable to contain at least one element selected from the group consisting of 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. If the supported amount of the catalyst (catalyst metal + support) is less than 10 g / L, the catalytic action may not be easily exhibited. On the other hand, if it exceeds 400 g / L, the pressure loss increases and the manufacturing cost may increase. If necessary, a catalyst is supported on the partition walls 4 of the cells 3 of the honeycomb structure 1. 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.

  Further, the second fluid circulation portion 6 is formed by the inner peripheral surface 24 of the casing 21 and the outer peripheral surface 7 h of the honeycomb structure 1. The second fluid circulation part 6 is a second fluid circulation part formed by the casing 21 and the outer peripheral surface 7 h of the honeycomb structure 1, and is separated by the first fluid circulation part 5 and the partition wall 4 of the honeycomb structure 1. The heat of the first fluid flowing through the first fluid circulation part 5 is received via the partition wall 4 and is transferred to the heated body as the second fluid flowing. The first fluid and the second fluid are completely separated, and these fluids do not mix.

  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 travels linearly from one inlet 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.

  In the heat exchanger 30, 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 allows the heat of the first fluid to be efficiently conducted to the honeycomb structure 1 by circulating the first fluid having a temperature higher than that of the second fluid in the cells of the honeycomb structure 1. Can do. That is, the total heat transfer resistance is the thermal resistance of the first fluid + the thermal resistance of the partition wall + the thermal resistance of the second fluid, but the rate-limiting factor is the thermal resistance of the first fluid. In the heat exchanger 30, since the first fluid passes through the cell 3, the contact area between the first fluid and the honeycomb structure 1 is large, and the thermal resistance of the first fluid, which is a rate-determining factor, can be reduced. .

  In the present invention, extrusion molding can basically 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.

  The heat exchanger 30 includes a honeycomb structure 1 that is the first fluid circulation portion 5 (high temperature side) of the honeycomb structure through which the first fluid (heating body) circulates and a casing in which the inside is the second fluid circulation portion 6. 21. Since the first fluid circulation part 5 is formed of the honeycomb structure 1, heat exchange can be performed efficiently. In the honeycomb structure 1, a plurality of cells 3 serving as flow paths are defined by partition walls 4, and the cell shape is appropriately set to a desired shape from a circle, an ellipse, a triangle, a quadrangle, and other polygons. Just choose.

  The shape of the honeycomb structure 1 is a cylinder, but the shape is not limited to this, and may be another shape such as a quadrangular prism. FIG. 5A shows a cross-sectional view taken along a plane perpendicular to the axial direction of the heat exchanger 30 when the heat exchange member 11 is a square pillar honeycomb structure 1, and FIG. 5B shows a perspective view thereof.

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 smaller than 25 cells / square inch, the strength of the partition walls 4, and consequently the strength of the honeycomb structure 1 itself and the effective GSA (geometric surface area) may be insufficient. On the other hand, if the cell density exceeds 2000 cells / square inch, the pressure loss when the heat medium flows may increase.

  The number of cells per honeycomb structure 1 (per module) is preferably 1 to 10,000, and particularly preferably 200 to 2,000. 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. In addition, 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 500 μm. If the wall thickness is less than 50 μm, the mechanical strength may be reduced, and damage may be caused by impact or thermal stress. On the other hand, if it exceeds 2 mm, there is a possibility that problems such as a decrease in the cell volume ratio on the honeycomb structure side, an increase in fluid pressure loss, and a decrease in the heat exchange rate through which the heat medium permeates may occur.

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 . When it is less than 0.5 g / cm ³ , the partition wall 4 has insufficient strength, and the partition wall 4 may be damaged by pressure when the first fluid passes through the flow path. On the other hand, if it exceeds 5 g / cm ³ , the honeycomb structure 1 itself becomes heavy, and the characteristics of weight reduction may be impaired. 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.

  Next, an embodiment in which the honeycomb structure 1 that is the heat exchange member 11 has an extended outer peripheral wall 51 that extends outward in the axial direction from the axial end surface 2 of the honeycomb portion 52 and is formed in a cylindrical shape. Indicates. 2A is a perspective view of the honeycomb structure 1 having the extended outer peripheral wall 51, and FIG. 2B is a cross-sectional view cut along a cross section parallel to the axial direction. 3A is a perspective view of the heat exchanger 30 in which the honeycomb structure 1 having the extending outer peripheral wall 51 is accommodated in the casing 21, and FIG. 3B is a cross-sectional view cut along a cross section parallel to the axial direction. FIG. 3C shows a cross-sectional view cut along a cross section perpendicular to the axial direction.

  As shown in FIGS. 2A to 2B, the honeycomb structure 1 as the heat exchange member 11 extends from the axial end surface 2 of the honeycomb portion 52 outward in the axial direction and extends in the tubular shape. have. The extended outer peripheral wall 51 is formed continuously and integrally with the outer peripheral wall of the honeycomb portion 52. On the inner peripheral surface side of the outer peripheral wall extending outer peripheral wall 51, the partition walls 4, the cells 3 and the like are not formed, and are hollow. The central honeycomb portion 52 is the heat collecting portion 12 that promotes heat transfer.

  3A to 3D show an embodiment of the heat exchanger 30 in which the honeycomb structure 1 having the extending outer peripheral wall 51 is accommodated in the casing 21. 3A is a perspective view, and FIG. 3B is a cross-sectional view cut along a cross section parallel to the axial direction. FIG. 3C shows that the casing 21 is integrally formed with a cylindrical portion 21a that fits to the outer peripheral surface 7h of the honeycomb structure 1 and an outer casing portion 21b that forms the second fluid circulation portion 6 outside the cylindrical portion 21a. An embodiment provided as: FIG. 3D is a cross-sectional view taken along a cross section perpendicular to the axial direction.

  In the embodiment of FIGS. 3A to 3B, the casing 21 of the heat exchanger 30 has the honeycomb structure 1 that forms the first fluid circulation portion 5 from the first fluid inlet 25 to the first fluid outlet 25. The honeycomb structure 1 is provided to be fitted to the casing 21 so as to be fitted, and the outer peripheral surface of the extended outer peripheral wall 51 of the honeycomb structure 1 and the inner peripheral surface of the casing 21 are provided. Thus, a seal portion 53 is formed. The inlet 22 and the outlet 23 of the second fluid are formed on the same side with respect to the honeycomb structure 1. In the present embodiment, the second fluid circulation portion 6 has a circulation structure that circulates around the outer periphery of the honeycomb structure 1. That is, the second fluid flows around the outer periphery of the honeycomb structure 1 (see FIG. 3D).

  FIG. 3C shows that the casing 21 is integrally formed with a cylindrical portion 21a that fits to the outer peripheral surface 7h of the honeycomb structure 1 and an outer casing portion 21b that forms the second fluid circulation portion 6 outside the cylindrical portion 21a. Embodiment of the heat exchanger 30 provided as is shown. FIG. 3D is a cross-sectional view taken along a cross section perpendicular to the axial direction. The tubular portion 21a has a shape corresponding to the shape of the outer peripheral surface 7 of the honeycomb structure 1, and the outer casing portion 21b has a space for the second fluid to flow outside the tubular portion 21a. It has a cylindrical shape. A second fluid inlet 22 and outlet 23 are formed in a part of the outer casing portion 21b. In the present embodiment, the second fluid circulation part 6 is formed to be surrounded by the cylindrical part 21a and the outer casing part 21b, and the second fluid that circulates through the second fluid circulation part 6 is a honeycomb structure. The heat is exchanged by circulating in the circumferential direction on the outer peripheral surface 7h of 1 without being in direct contact with the outer peripheral surface 7 of the honeycomb structure 1. With such a configuration, even when the honeycomb structure 1 is damaged, the first fluid and the second fluid do not leak or mix.

  3B shows an embodiment in which the blocking portion 13 is configured to include one or more metal layers. In the left enlarged view, a metal impregnated layer 7 i is formed on the extended outer peripheral wall 51, and a bonding metal layer 7 k for bonding the extended outer peripheral wall 51 and the casing 21 is further formed. Further, as shown in the enlarged view on the right side, a metal impregnated layer 7i is formed on the SiC outer peripheral wall 7a of the honeycomb portion, and a metal plate 7j in contact with the second fluid may be provided. it can.

  4A is a perspective view of the heat exchanger 30 in which the honeycomb structure 1 having the extending outer peripheral wall 51 is accommodated in the casing 21, and FIG. 4B is a cross-sectional view cut along a cross section parallel to the axial direction. 4C shows a cross-sectional view cut along a cross section perpendicular to the axial direction. As shown in FIGS. 4A to 4C, the casing 21 of the heat exchanger 30 of the present embodiment is a honeycomb that forms the first fluid circulation part 5 from the first fluid inlet 25 to the first fluid outlet 25. 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 the casing 21, and a seal portion 53 is formed by the outer peripheral surface of the extended outer peripheral wall 51 of the honeycomb structure 1 and the inner peripheral surface of the casing 21. A second fluid inlet 22 and outlet 23 are formed on opposite sides of the honeycomb structure 1.

  In order to improve the reliability of the heat exchanger 30, it is effective to suppress heat transfer from the high-temperature fluid (first fluid) side to the seal part 53 and to suppress the temperature rise of the seal part 53. In the embodiment, since the extended outer peripheral wall 51 is formed and the extended outer peripheral wall 51 serves as the seal portion 53, the performance of the heat exchanger 30 is improved. For example, in the structure of FIGS. 1A and 1B, the vicinity of the end surface 2 on the inlet side of the honeycomb structure 1 that is the inlet of the first fluid is the highest temperature, but a joint with the casing 21 and a seal portion (seal portion 11) are necessary. For this reason, it is difficult to flow the second fluid to the extreme end. By providing the extended outer peripheral portion 51 as in this embodiment, the end portion of the honeycomb portion 21 (in the vicinity of the end surface 2 on the inlet side) can also be heat-exchanged. In other words, since the seal portion 53 is formed on the outer side in the axial direction than the honeycomb portion 52, the second fluid can contact the entire outer peripheral surface of the honeycomb portion 21. For this reason, heat exchange efficiency can be improved.

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

(Examples 1-12)
A heat exchanger 30 in which the first fluid circulation part and the second fluid circulation part were formed by the heat exchange member 11 (honeycomb structure 1) and the casing 21 was produced as follows.

(Manufacture of honeycomb structure)
The heat exchange member 11 of Examples 1 to 12 and Comparative Example 1 was manufactured as follows.

(Examples 1-6)
After extruding the clay containing the ceramic powder into a desired shape, drying and firing, a cylindrical honeycomb structure 1 having a material of silicon carbide, a main body size of 50 mm in diameter, and a length of 100 mm was manufactured. The SiC outer peripheral wall 7a of the honeycomb structure 1 was impregnated with metal (Si) to form a metal impregnated layer 7i to obtain a heat exchange member 11 (see FIG. 1B).

(Examples 7 to 12)
In the same manner as in Example 1, a honeycomb structure 1 was manufactured. Without impregnating the SiC outer peripheral wall 7a with metal, a metal plate 7j (SUS) was wound around the SiC outer peripheral wall 7a to form the heat exchange member 11 (see FIG. 1D).

(casing)
As an outer container of the heat exchange member 11 (honeycomb structure 1), a casing 21 made of stainless steel was used. In Examples 1 to 12, one heat exchange member 11 (honeycomb structure 1) was disposed in the casing 21 (see FIGS. 3C and 3D). As shown in FIG. 6, the interval 15 b between the honeycomb structure 1 and the casing was set to be the same as the cell length 15 a of the honeycomb structure 1. 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 12 were the same.

(Comparative Examples 1-3)
In the same manner as in Example 1, a honeycomb structure 1 was manufactured. The SiC outer peripheral wall 7a was coated with the same kind of paste as the outer peripheral wall and the honeycomb portion (heat collecting portion) and baked to densify the SiC outer peripheral wall 7a, whereby the blocking portion 13 was obtained.
(Comparative Examples 4-6)
In the same manner as in Example 1, honeycomb structure 1 was manufactured using a cordierite material. A metal plate 7j (SUS) was wound around the cordierite outer peripheral wall without impregnating the cordierite outer peripheral wall with metal, and the heat exchange member 11 was obtained.

  Table 1 shows the configuration of the heat exchange member 11. The porosity of the blocking part in Table 1 is the porosity of the densest part of the blocking part 13. That is, in Examples 1-6, it is the porosity of the metal impregnation layer 7i, and in Examples 7-12, it is the porosity of the metal plate 7j. In addition, the amount of metal contained in Table 1 is a value when Si of the silicon carbide pillar is not metalized.

(First fluid and second fluid)
The inlet temperature and flow rate of the first fluid to the heat exchange member 11 (honeycomb structure 1) and the inlet temperature and flow rate of the second fluid into the casing 21 were all the same. As the first fluid, 400 ° C. nitrogen gas (N ₂ ) was used. Moreover, 20 degreeC water was used as a 2nd fluid.

(Test method for heat exchange efficiency)
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 SV (space velocity) of nitrogen gas with respect to the honeycomb structure 1 was set to 50,000 h ⁻¹ . The flow rate of (cooling) water was 5 L / min. The (cooling) water flowed outside the pipe (gap 1 mm).

(Test results)
Table 1 shows the heat exchange rate. The heat exchange rate (%) was calculated by Equation 1 by calculating energy amounts from the outlet temperature and the inlet temperature of the honeycomb structure 1 of the first fluid (nitrogen gas) and the second fluid (water), respectively.
(Equation 1) Heat exchange rate (%) = ((outlet temperature of heated body (second fluid) −inlet temperature of heated body (second fluid)) × heated body (second fluid) Specific heat) ÷ (Inlet temperature of heated body (first fluid) −Outlet temperature of heated body (second fluid)) × Specific heat of heated body (first fluid)

(Durability test of heat exchange member)
Each heat exchange member 11 was heated to 400 ° C., and durability was examined. The results are shown in Table 1.
The durability of the heat exchange member 11 in the heat exchanger 30 was examined by a heat exchange efficiency test using nitrogen gas (N ₂ ) at 400 ° C. as the first fluid and water at 20 ° C. as the second fluid. The results are shown in Table 1. When the porosity of the blocking portion was 0.1% or less and the porosity excluding the metal of the blocking portion was 0%, the sample broke during the test.

(Adhesion)
The adhesion between the honeycomb structure 1 of the heat exchange member 11 and the metal plate 7j (SUS) was evaluated from the heat exchange efficiency. The evaluation criteria were as follows: 熱 when the heat exchange efficiency was 95% or more, ◯ when the heat exchange efficiency exceeded 90% but less than 95%, and △ when the heat exchange efficiency was 90% or less.

  In Comparative Examples 1 to 3, in which the SiC outer peripheral wall 7a was densified with the same kind of paste as the SiC outer peripheral wall 7a and the honeycomb portion (heat collecting portion 12), cracks occurred. On the other hand, in Examples 1 to 12, in which the outer peripheral wall 7 serving as the blocking portion 13 contains metal (impregnation, winding), cracks did not occur and durability was improved. Durability is improved by including a metal in the blocking portion. In Comparative Examples 4 to 6 in which a ceramic honeycomb was used as a cordierite material, cracks did not occur, but the heat exchange efficiency was small.

  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). In particular, it is suitable when at least one of the heated body or the heated body is a liquid. 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 surface (in the axial direction), 3: cell, 4: partition wall, 5: first fluid circulation portion, 6: second fluid circulation portion, 7: outer peripheral wall, 7h: outer peripheral surface, 7i : Metal impregnated layer, 7j: Metal plate, 7k: Bonded metal layer, 7m: Line part, 11: Heat exchange member, 12: Heat collecting part, 13: Blocking part, 15a: Cell length, 15b: Interval, 21: Casing, 21a: cylindrical part, 21b: outer casing part, 22: (second fluid) inlet, 23: (second fluid) outlet, 30: heat exchanger, 51: extended outer peripheral wall, 52 : Honeycomb part, 53: seal part.

Claims (7)

A heat collecting section formed as a honeycomb structure having a plurality of cells through which a first fluid as a heating body is formed, which is partitioned by SiC partition walls;
A dense dense portion disposed on the outer periphery of the heat collecting portion, having an SiC outer peripheral wall formed of SiC, and at least a portion including a metal and made of a material different from the heat collecting portion; Formed as an outer peripheral wall having a blocking portion that blocks the flow of fluid,
A second fluid having a temperature lower than that of the first fluid is circulated on the outer peripheral surface side of the blocking portion, and at least one of the first fluid and the second fluid is separated from each other by the blocking portion. A heat exchange member that exchanges heat between the first fluid and the second fluid through the blocking portion in a state. The porosity difference between the heat collecting part and the blocking part is 10% or more,
2. The heat exchange member according to claim 1, wherein a difference in metal content between the heat collecting portion and the portion including the metal in the blocking portion is 10% or more.   3. The heat exchange member according to claim 1, wherein the blocking portion includes more metal on the outer peripheral surface side than on the inner peripheral surface side.   4. The heat exchange member according to claim 1, wherein the blocking portion includes one or more metal layers.   The said interruption | blocking part is comprised by the SiC outer peripheral wall integrally formed with the said heat collection part with SiC, and the metal body with which the outer peripheral surface of the said SiC outer peripheral wall was equipped. The heat exchange member according to Item 1.   The surface roughness Ra of the outer peripheral surface, which is the surface of the SiC outer peripheral wall facing the metal body, is 0.5 μm or more, and the outer peripheral surface extends in the axial direction of the flow direction of the first fluid. The heat exchange member according to claim 5, wherein a streak-like line portion is formed.   7. The heat exchange member according to claim 1, wherein the blocking portion has a porosity of the outer peripheral wall excluding metal of 10% or more.

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