JP2016530477A - Bonded heat exchanger matrix and corresponding bonding method - Google Patents

Abstract

The present invention relates to a stack of components (4, 5), or a combination of both types of stacks, in particular an etching plate or wave plate (4), a separate metal sheet (5) and a bar (6). Wherein at least a portion of the component (4, 5) includes a corrosion inhibitor and provides a thermal conductivity of the adhesive of 2-5 W / m / K to the adhesive of 20-60 wt% It relates to a metal heat exchanger matrix characterized in that it is joined together by a layer (15) of epoxide resin structural adhesive filled with conductors, preferably having a thickness of 20-150 μm. Preferably, the present invention is applicable to corrosive environments, particularly marine environments.

Description

  The invention relates to the field of metal heat exchangers, in particular of the type comprising an etching plate, comprising a separate metal sheet, comprising bars and fins, or a combination of both of these types, in particular aluminum.

  Because of their very good energy performance characteristics and mechanical strength and light weight at extremely low temperatures, such heat exchangers are currently used to liquefy natural gas and methods for separating gas from air. Used in the method.

  As is known, the matrix of such a heat exchanger is assembled by brazing and the fluid dispensing head is welded onto the brazed matrix.

  The heat exchanger thus formed has purely metallic properties and is susceptible to corrosion damage. The field of application of this heat exchanger is therefore limited to clean and less corrosive environments. In particular, such heat exchangers do not support seawater and marine atmosphere.

  The cause of this incompatibility arises from diffusion phenomena related to the interface between the heat exchanger components and brazing, which causes metallurgical modification of the initial material. After cooling, it is believed that intermetallic deposits are one of the major causes of the formation of corrosion pits after the formation of electrochemical cells that favor adjacent metal-based etching.

  Although corrosion resistant coatings exist, the application of corrosion resistant coatings to these types of devices remains a problem. The corrosion resistant coating may be applied to the individual components of the matrix before the assembly and brazing steps, or it may be applied to the finished matrix after brazing.

  This first method has the disadvantage that only corrosion-resistant coatings that remain stable at the brazing temperature and that do not disturb the brazing can be used. The second method does not allow the corrosion resistant coating to be applied uniformly and throughout the braze matrix, as the braze matrix includes a number of difficult to reach tears.

  Accordingly, it is an object of the present invention to form a heat exchanger metal matrix that remains robust and suitable heat conductors while at the same time being more resistant to corrosion. Such matrices must be particularly adapted for marine applications.

  According to the invention, this object is characterized in particular by a stack of components that are etching plates or fins, a stack of components that are separate metal sheets and bars, or a combination of both types of stacks. 20-60 mass realized by a matrix, at least part of which is based on an epoxy resin containing a corrosion inhibitor and ensures the thermal conductivity of an adhesive of 2-5 W / m / K Are bonded together by a layer of structural adhesive, preferably with a thickness of 20-150 μm, which is filled with% heat conductor.

  By gluing at least a portion of the matrix components with the adhesive, it is possible to eliminate brazing and conventional filler metals that are susceptible to corrosion damage. The selected adhesive formulation protects the matrix from corrosion and retains its mechanical and thermal performance.

  The matrix according to the invention is particularly advantageous in heat exchangers that are placed in corrosive environments, such as marine media, regardless of whether the heat exchanger is submerged or placed in the marine atmosphere. Applies to

In a preferred embodiment, the matrix according to the invention comprises one, some or all of the following features in any technically feasible combination.
The heat conductor of the adhesive is based on metal and / or ceramic.
-The corrosion inhibitor of the adhesive is based on zinc oxide.
The component is coated with an adhesive holder, in particular a layer of a conversion layer and / or an adhesive holding primer.
The conversion layer has a thickness of 1-50 μm, and preferably 5-20 μm.
The component is made of aluminum or an aluminum alloy and the conversion layer is made of alumina.
-Some of the components are brazed together.

  The invention further comprises a heat exchanger comprising a matrix as defined above and preferably comprising at least one head for fluid dispensing, in particular bonded to the matrix by means of the adhesive. Related.

  Another object of the present invention is to realize a method for assembling a heat exchanger metal matrix adapted to a corrosive environment.

According to the invention, this object is a method of assembling a heat exchanger matrix,
a) providing the components of the matrix;
b) 20-60 mass% thermal conductor which is a structural adhesive based on an epoxy resin containing a corrosion inhibitor and ensures the thermal conductivity of the adhesive at 2-5 W / m / K Depositing a structural adhesive filled with at least a portion of the component;
c) stacking the components to obtain a stack;
d) oven curing the stack to cure the adhesive and thereby obtain a matrix;
Realized by the method characterized by

In a preferred embodiment, the method according to the invention comprises one, some or all of the following features in any technically feasible combination.
-A step consisting of applying an adhesive holder on the component before step b).
The application of the adhesive holder is a first step, which is anodization or phosphorylation, and / or retaining primer by dipping the component in the primer or by firing the primer on the component A second stage of applying.
-Drying and heating the component coated with the holding primer for a period of 30-120 minutes and at a temperature of 50-200 ° C so as to bind the holding primer to the component.
-Step b)
i) providing the adhesive as a paste and spreading the adhesive on the component by a doctor blade, or
ii) co-laminating adhesives on the components;
including.
Stage d) maintains the stack at a temperature of 50-120 ° C. for a minimum period of 30 minutes, followed by a temperature of 150-250 ° C. for a minimum duration of 1 hour A second stage.
Stage d) comprises a stage for maintaining the stack in a compressed state at a pressure higher than 100 kPa.

  The present invention lies in a particular number of other configurations described more clearly below with respect to the exemplary embodiments described with reference to the accompanying drawings, apart from the configurations described above, and these embodiments. Is non-limiting.

FIG. 3 is a perspective exploded view of a matrix during stacking according to an exemplary embodiment of the present invention. FIG. 2 shows a detail portion 7 of the matrix of FIG. 1 showing adhesive bonding of the matrix components. It is a figure which shows the process of the isolation | separation metal sheet | seat of the matrix of FIG. 1 by the assembly method of this invention. It is a figure which shows the process of the isolation | separation metal sheet | seat of the matrix of FIG. 1 by the assembly method of this invention. It is a figure which shows the process of the isolation | separation metal sheet | seat of the matrix of FIG. 1 by the assembly method of this invention. It is a figure which shows the process of the isolation | separation metal sheet | seat of the matrix of FIG. 1 by the assembly method of this invention. FIG. 2 is a diagram illustrating processing of fins of the matrix of FIG. 1 according to the assembly method of the present invention. FIG. 2 is a diagram illustrating processing of fins of the matrix of FIG. 1 according to the assembly method of the present invention. FIG. 2 is a diagram illustrating processing of fins of the matrix of FIG. 1 according to the assembly method of the present invention.

  Next, in order to make the explanation of the present invention easier to understand, the present invention is also applied to a heat exchanger matrix having separated metal sheets, bars, and fins or an etching plate. In view of this, reference is made to a heat exchanger comprising separate metal sheets, bars, and combinations of fins and etching plates. Next, the aluminum matrix will be described. However, the present invention also includes in its scope matrices made of other metals, particularly steel.

  Referring to FIG. 1, the stack of matrix 2 formed is schematically shown. As is known, the matrix 2 consists of a stack of components, namely fins 4, separating metal sheets 5 and aluminum bars 6.

  The features of the matrix 2 can be seen in FIG. An enlarged view of the area 7 of the matrix 2 shown in FIG. 1 is identified in this figure. The fin 4 is disposed between the two separated metal sheets 5 and bonded to the separated metal sheet 5. Both separating metal sheets 5 have two oppositely facing surfaces 8, 9 and the fin 4 has two oppositely facing surfaces 10,11.

  According to the invention, the separating metal sheet 5 and the fins 4 are covered by the adhesive holder 12 on their two opposite faces 8, 9, 10, 11. The adhesive holder 12 consists of two layers, a conversion layer 13 extending over the surfaces 8, 9, 10, 11 and a layer 14 of adhesive-carrying primer deposited on the conversion layer 13. The conversion layer 13 is made of alumina. The primer layer 14 is made of a resin from the group of epoxide resins with integrated corrosion inhibitors such as zinc salts. The conversion layer 13 has a thickness I of 1-50 μm, preferably a thickness I of 5-20 μm. The primer layer 14 preferably has a thickness d of several micrometers.

  Adhesive layers 15 deposited on the sides 8, 9 on both sides of the metal separation sheet 5 ensure the connection between the separation metal sheet 5 and the fins 4. Preferably, the thickness e of the adhesive layer 15 is 20-100 μm.

  Adhesive 15 is a structural adhesive from the group of epoxide resins. The adhesive 15 includes a corrosion protection element such as a zinc salt or zinc oxide. The adhesive 15 is further filled with an additional element of 20-60% by weight, for example derived from metal or ceramic, which greatly increases its thermal conductivity. Therefore, the thermal conductivity of the adhesive 15 is between 2-5 W / m / K.

  Next, a method for assembling the matrix 2 will be described with reference to FIGS.

  In the first stage, the separating metal sheet 5 (an example is shown in FIG. 3), the fins 4 (an example is shown in FIG. 7) and the bar 6 of the matrix 6 are made of aluminum.

In the second stage, the opposite surfaces 8 and 9 of the separation metal sheet 5, the opposite surfaces 10 and 11 of the fin 4, and the bar 6 are converted into an alumina (Al ₂ O ₃ ) conversion layer 13. Anodized to grow. This anodization is preferably sulfuric acid anodization or chromic acid anodization. The results are shown in FIGS. 4 and 8.

  If the matrix 2 is assembled from steel components, the anodization will be replaced by a phosphorylation process.

  In the third stage, the conversion layer 13 is covered with a holding primer layer 14. This step is preferably carried out by immersing the bar 6, the fins 4 and the separating metal sheet 5 in an aqueous solution of holding primer. Thus, the components 4, 5, 6 are covered by the holding primer. As an alternative, the holding primer 14 is deposited on the components 4, 5, 6 by firing.

  It will be ensured that the application of the holding primer 14 is carried out in a uniform manner over the surface in order to ensure a proper adhesion of the whole component 4, 5, 6 thereafter. The results of this third stage are shown in FIGS.

  After application of the holding primer 14, drying and heating are performed to chemically bond the holding primer 14 to the treated surface. The connection between the holding primer 14 and the anodized surface 13 is preferably obtained by a hot air treatment carried out at a temperature of 50-200 ° C. for a time that is preferably in the range of 30-120 minutes. In a particularly preferred form, the anodized components 4, 5, 6 coated with the holding primer 14 are maintained at about 90 ° C. for about 120 minutes.

  In the fourth stage, the adhesive 15 is applied only on the holding primer 14 of the separating metal sheet 5. This may be done as an adhesive paste that is uniformly deposited in the layer by a doctor blade to a sufficient and uniform thickness, or a thin film that is laminated on the separating metal sheet 5 is deposited. Or by any other means that makes it possible to provide an adhesive deposit on the separating metal sheet 5. The application of the adhesive 15 adheres to a residual thickness of about 20-150 μm as much as possible in order to ensure both the role of the binder and the role of protecting the underlying separating metal sheet 5. Should. The result of the fourth stage is shown in FIG.

  The fact that steps 2 to 4 can be performed on individual components 4, 5, 6 that are easily accessible to the surface is a clear advantage. Adjustment of predetermined parameters such as deposit thickness or uniformity is facilitated by adhering to this method. The method according to the invention is thus advantageously distinguished from a method in which the preparation of the surfaces of the components 4, 5, 6 is performed after the assembly of the stack 3.

  In the fifth stage, the components 4, 5, 6 are stacked to obtain the stack 3.

  The sixth stage consists of an oven curing stage at a temperature below 150 ° C. of the stack 3 in order to cure (polymerize) the adhesive 15. At the end of this oven curing, a matrix 2 is obtained which is firm and corrosion resistant. This oven curing consists, for example, in heating and maintaining the stack 3 at 90 ° C. for 4 hours and then heating and maintaining the stack 3 at 120 ° C. for 1 hour. This may be done in a press oven, in an oven with forced convection, or by any other equivalent heating method. In order to optimize the connection of the components 4, 5, 6 during the polymerization process, an apparatus for clamping the stack is preferably used. The clamping device may maintain the components 4, 5, 6 under a constant load, for example exceeding 100 kPa.

  The completed matrix 2 may then be equipped with a fluid dispensing head to form a heat exchanger. The fluid dispensing head may be directly bonded to the surface of the matrix 2 by the adhesive 15.

  Alternatively, the fluid dispensing head is welded to the matrix 2 via intermediate parts pre-nested in the form of the matrix 2 when stacked according to a female / male configuration. The intermediate part makes it possible to move the weld zone far enough away from the matrix 2 to prevent deterioration of the adhesive joint of the matrix 2 due to the high temperatures prevailing during welding. In this case, the seal of the connecting part between the intermediate part and the matrix 2 is ensured by the elastomer whose main component is silicone.

  With the assembly method according to the invention, each metal component 4, 5, 6 is covered with multiple layers that act as a barrier to the diffusion and propagation of corrosion sources.

  In another embodiment of the invention, certain components 4, 5, 6 of the matrix 2 are brazed and the others are joined by adhesive bonding. For example, the fluid passages of the matrix 2 intended to receive corrosive fluids such as seawater are defined by adhesively bonded components 4, 5, 6 while the working pressure, for example ammonia, is The fluid passages of the matrix 2 intended for use for fluids outside the range of use of the adhesive 15 are defined by brazed components 4, 5, 6.

  In order to realize this mixed type assembly, in a first stage, the components 4, 5, 6 that must be brazed are brazed by the usual method for producing brazed heat exchangers. Is done. The subassembly of matrix 2 is formed with all of these components 4, 5, 6, noting that there is brazing only on the surface that must be brazed. After brazing, the brazed subassembly and the remaining components 4, 5, 6 are covered with adhesive 15 and stacked to form the stack 3. Next, the oven curing described above is performed on the stack 3 (sixth stage). The low temperature of oven curing makes it possible not to degrade the brazing performed in the first stage.

  In another embodiment of the invention, the adhesive bonded / brazed mixed matrix is assembled using low temperature brazing (melting temperature of brazing below 200 ° C.). This is done by first assembling the entire stack 3 with its subassembly with adhesive and brazing, and then oven curing the stack 3 to fuse the brazing while curing the adhesive. Make it possible to do.

  With the adhesive bonding of the present invention, the proposed heat exchanger matrix can be applied in a corrosive environment while retaining the required thermal performance and pressure resistance. Furthermore, the method according to the invention makes it possible to assemble a large volume heat exchanger matrix.

Claims (15)

In particular, characterized by a stack of components (4, 5, 6), or a combination of both types of stacks, which are etching plates or fins (4), separate metal sheets (5) and bars (6) A heat exchanger metal matrix (2), comprising:
At least a portion of the components (4, 5, 6) is based on an epoxide resin containing a corrosion inhibitor and ensures the thermal conductivity of an adhesive of 2-5 W / m / K 20-60 Joined together by a layer (15) of structural adhesive, preferably having a thickness of 20-150 μm, filled with mass% heat conductor,
Heat exchanger metal matrix (2). The thermal conductor of the adhesive (15) is mainly composed of metal and / or ceramic.
The matrix according to claim 1. The corrosion inhibitor of the adhesive (15) is mainly composed of zinc oxide.
The matrix according to claim 1. Said components (4, 5, 6) are coated with an adhesive holder (12), in particular a conversion layer (13) and / or a layer of adhesive-carrying primer (14),
The matrix according to any one of claims 1 to 3. The conversion layer (13) has a thickness of 1-50 μm, preferably 5-20 μm,
The matrix according to claim 4. The components (4, 5, 6) are made of aluminum or aluminum alloy;
The conversion layer (13) is made of alumina,
The matrix according to claim 4 or 5. A part of the component (4, 5, 6) is brazed integrally,
The matrix according to any one of claims 1 to 6. Matrix (2) according to any one of claims 1 to 7,
Preferably, at least one fluid dispensing head that is adhered to the matrix (2), in particular by the adhesive (15);
Including heat exchanger. A method for assembling a heat transformer metal matrix (2) comprising:
a) providing the components (4, 5, 6) of the matrix (2);
b) A structural adhesive (15) based on an epoxide resin containing a corrosion inhibitor, which ensures the thermal conductivity of the adhesive of 2-5 W / m / K and is 20-60% by mass. Applying a structural adhesive (15) filled with a thermal conductor of at least a portion of said component (4, 5, 6);
c) stacking said components (4, 5, 6) to obtain a stack (3);
d) oven curing the stack (3) to cure the adhesive (15) and thereby obtain the matrix (2);
Characterized by,
Method. Further comprising applying an adhesive holder (12) on the component (4, 5, 6) prior to step b);
The method of claim 9. The step of applying the adhesive holder (12) is a first step of anodizing or phosphorylating and / or a second step of applying a holding primer (14), wherein the component is included in the primer. Applying the retaining primer (14) by soaking or by firing the primer onto the component;
The method of claim 10. The component (4, 5) coated with the retention primer (14) at a temperature between 50-200 ° C for a period of 30-120 minutes to bind the retention primer (14) to the component. 6) is further dried and heated.
The method of claim 11. Said step b)
i) providing the adhesive (15) as a paste and spreading the adhesive on the component by a doctor blade, or
ii) interlaminating the adhesive (15) on the component (5);
The method according to any one of claims 9 to 12. Step d) comprises a first step of maintaining the stack (3) at a temperature of 50-120 ° C. over a minimum period of 30 minutes, followed by a temperature of 150-250 ° C. over a minimum period of 1 hour. Maintaining a stack (3), and
14. A method according to any one of claims 9 to 13. Step d) comprises maintaining the stack (3) in a compressed state at a pressure higher than 100 kPa;
15. A method according to any one of claims 9 to 14.

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