KR20160058099A - Bonded heat exchanger matrix and corresponding bonding method - Google Patents

Abstract

The stacking of the elements 4, 5, in particular of the type of the etched plate or fins 4, the separating metal sheet 5 and the stack of bars, Characterized in that the at least one part of the component (4, 5) is a heat exchanger metal matrix (2) characterized by a combination of a structural adhesive based on an epoxy resin containing a corrosion inhibitor, And 20 to 60 mass% of a thermal conductor which is bonded together with a layer 15 having a thickness comprised between 20 and 150 占 퐉 and which ensures the thermal conductivity of the adhesive is 2 to 5 W / m / K. Preferred applications for corrosive environments, especially marine environments.

Description

BONDED HEAT EXCHANGER MATRIX AND CORRESPONDING BONDING METHOD < RTI ID = 0.0 >

The present invention relates to the field of metal heat exchangers, especially in aluminum, comprising a combination of this type of both, of a type with an etched plate, a separating metal sheet, a bar and a type with a pin The invention relates to the field of metal heat exchangers, notably in aluminum, of the type with etched plates, of separating metal sheets, of bars and fins or of a combination of both of these types.

These heat exchangers are now being used in methods for liquefying natural gas and separating gases from the air because of their very good energy, very low temperature mechanical strength and lightness.

In a known manner, these heat exchanger matrices are assembled by brazing, and their fluid-dispensing heads are welded to the brazed matrix.

The heat exchanger thus formed is entirely of a metal nature and sensitive to corrosion. Thus, applications in these fields are limited to clean, non-corrosive environments. In particular, they can not be provided in seawater or marine air.

The origin of this incompatibility is due to the diffusion phenomena involved in the interface of the brazing and the components of the exchanger, leading to metallurgical modifications of the initial material. After cooling, the presence of a precipitate of the alloy is presumed to be one of the major causes of the generation of corrosion pits after forming an electrochemical space that favored etching of the adjacent metal base (After cooling, the presence of intermetallic precipitates is assumed to one of the major causes of the corrosion pits, followed by the formation of electrochemical cells favoring etching of the adjacent metal base.

Anticorrosion coatings exist, but their application in this type of environment remains a problem. The anti-corrosive coating may be applied to the individual components of the matrix prior to the assembly and brazing step, or to the completed matrix after brazing.

The first method has the disadvantage of being able to use only the corrosion inhibiting coating which remains stable at the brazing temperature without agitating the brazing. The second method does not provide the possibility of uniformly depositing the anti-corrosion coatings and throughout the brazing matrix, since the latter includes many crevices with access difficulties.

It is therefore an object of the present invention to produce a heat exchanger metal matrix having better resistance to corrosion while maintaining solid and good thermal conductors. These matrices should be adjusted specifically for marine applications.

According to the invention, this object is achieved by means of a heat exchanger metal matrix characterized by a combination of components, in particular an etched plate or fin, a separating metal sheet and a stack of bars, or both types of stacks And at least one portion of the component is bonded together with a layer of a structural adhesive, preferably 20 to 150 탆 thick, based on an epoxy resin containing a corrosion inhibitor, the thermal conductivity of the adhesive being 2 to < RTI ID = And 20 to 60 mass% of a thermal conductor which ensures 5 W / m / K. (According to the invention, this is achieved by a heat exchanger metal matrix, characterized by a stack of components, notably of etched plates or of fins , separating metal sheets and bars, or a combination of both types of stacks, wherein at least one portion of said components are bound together by a layer, 50 μm, of a structural adhesive based on an epoxy resin containing a corrosion inhibitor and loaded with 20 to 60% by mass of a conductor ensuring a heat conductivity of the adhesive from 2 to 5 W / m / K.

By bonding at least a portion of the elements of the matrix by means of the adhesive, this is possible without the traditional filler metal and brazing sensitive to corrosion. With the selected adhesive formulation, the matrix is protected against corrosion and maintains its mechanical and thermal performance.

The matrix according to the invention finds particular application in heat exchangers located in the corrosive environment, in particular in the marine medium, whether the heat exchanger is immersed in the ocean atmosphere or in water.

According to a preferred embodiment, the matrix according to the invention comprises, in any technically possible combination, one, some or all of the following features:

The thermal conductor of the adhesive is based on a metal and / or ceramic;

The corrosion inhibitor of the adhesive is based on zinc oxide;

Said component being coated with a layer of an adhesive holder, in particular a conversion layer and / or an adhesive holding primer;

The conversion layer comprises 1 to 50 mu m and preferably has a thickness of 5 to 20 mu m;

The component is aluminum or an aluminum alloy, the conversion layer is of alumina;

Some of the components are brazed together.

The present invention also relates to a heat exchanger comprising a matrix as defined above and preferably at least one head for dispensing the adhesive (15) and the fluid attached to the matrix (2) .

Yet another object of the present invention is to achieve a method for assembling a heat exchanger metal matrix suitable for a corrosive environment.

According to the invention, this object is achieved by a method for assembling a heat exchanger metal matrix characterized by the following steps:

a) providing the component of the matrix;

b) a structural adhesive, based on an epoxy resin containing a corrosion inhibitor, loaded onto at least a portion of said component with 20 to 60% by weight of a thermal conductor which ensures a thermal conductivity of 2 to 5 W / m / K of said adhesive Depositing at least a portion of the substrate;

c) stacking the component to obtain a stack; And

d) curing the adhesive to oven the stack to obtain the matrix.

According to a preferred embodiment, the method according to the invention comprises, in any technically possible combination, one, some or all of the following features:

- applying an adhesive holder in said component before step b);

- the adhesive holder application comprises a second step of applying the holding primer by a first step of anodizing or phosphating and / or by dipping the component into the primer or by projecting the primer onto the component The adhesive holder comprises a first step of anodization or phosphorization, and / or a second step of applying a holding primer by dipping the component in the primer or projecting the primer on the component;

Drying and heating the component covered with the holding primer at a temperature comprised between 50 and 200 ° C for a period of 30 to 120 minutes to bond the holding primer to the component;

Step b) comprises:

I) providing the adhesive as a paste and spreading the adhesive to the component by a doctor blade, or

Ii) co-lamination of the adhesive to the component;

- the step d) comprises a first phase of holding the stack at a temperature comprised between 50 and 120 ° C for a minimum period of 30 minutes, followed by a first phase comprising 150 to 250 ° C for a minimum period of 1 hour And a second phase of maintaining the stack at a temperature.

Step d) comprises a phase of holding the stack under compression at a pressure of at least 100 kPa.

The present invention may be embodied in other specific arrangements, which are not to be construed as limitations, but which will be discussed more clearly hereinafter, with reference to the exemplary embodiments described with reference to the accompanying drawings, consist of. In the drawings:
Figure 1 is a perspective and exploded view illustration of a matrix during lamination in accordance with an exemplary embodiment of the present invention;
Figure 2 is a detail (7) of the matrix of Figure 1 showing the adhesive bonding of the components of the matrix;
Figures 3-6 illustrate the processing of a separating metal sheet of the matrix of Figure 1 according to the method of assembly of the present invention; And
Figures 7 to 9 show the processing of the pins of the matrix of Figure 1 according to the assembly method of the present invention.

Thereafter, in order to simplify the description of the present invention, it is recognized that the present invention is also applied to an etched plate and an exchanger, or to an exchanger comprising a combination of metal sheets, bars, and fins to be separated and an etched plate A heat exchange matrix with separating metal sheets, bars and pins. In addition, the aluminum matrix will be described next. Nevertheless, the invention also includes a matrix made of other metals, especially steel.

With respect to Figure 1, the stack of the produced matrix 2 may be represented diagrammatically as described. In the manner shown, the matrix 2 consists of a component, namely a fin 4, a separating metal sheet 5, and a stack 3 of aluminum bars 6.

The details of the matrix (2) are shown in Fig. The enlarged description of the region 7 of the matrix 2 shown in Fig. 1 is distinguished here. The pin 4 is located between two separating metal sheets 5 and is joined to the latter (A fin 4 is located between two separating metal sheets 5 and bound to the latter). Both separating metal sheets 5 have two opposing surfaces 8 and 9 and the pins 4 have two opposing surfaces 10 and 11, 8 and 9, and the fin 4 has two opposite faces 10 and 11).

According to the invention, the separating metal sheet 5 and the fins 4 are covered by the adhesive holder 12 and the two opposite surfaces 8, 9 and 10, 11 of the separating metal sheets 5 and the fin 4 are covered with their two opposite faces 8, 9 and 10, 11 with an adhesive holder 12). The adhesive holder 12 comprises two layers: a conversion layer 13 leading to the surfaces 8, 9, 10 and 11 and an adhesive holding primer layer deposited on the conversion layer 13, layer (14). The conversion layer 13 is made of alumina. The primer layer 14 consists of a resin from the family of epoxy resins with an integrated corrosion inhibitor, for example, a zinc salt. (The primer layer 14 consists of a resin from the family of epoxide resins which are integrated corrosion inhibitors, for example zinc salts). The conversion layer 13 contains 1 to 50 mu m and preferably has a thickness of 5 to 20 mu m. The primer layer 14 preferably has a thickness d of some micrometers.

An adhesive layer 15 deposited on the opposite surfaces 8,9 of both of the separating metal sheets 5 ensures the connection between the separating metal sheet 5 and the pins 4. Preferably, the thickness e of the adhesive layer 15 includes 20 to 100 mu m.

The adhesive 15 is a structural adhesive from a family of epoxy resins. The adhesive 15 contains corrosion inhibiting elements, such as zinc salts or oxides. The adhesive 15 is also loaded with, for example, 20 to 60% by weight of an additional component, which is a metal or ceramic source, which substantially increases its thermal conductivity (The adhesive 15 is also loaded with 20 to 60% by mass of additional elements, which increase its heat conductivity, for example of metal or ceramic origin). Therefore, the thermal conductivity of the adhesive 15 is located at 2 to 5 W / m / K.

The method for assembling the matrix 2 will not be described in Figures 3 to 9 at present.

In the first step, the separating metal sheet 5 is made of aluminum, the example shown in Fig. 3, the pin 4, the example shown in Fig. 7, and the bar 6 of the matrix 2 .

In the second step, the opposite surfaces 8, 9 of the separating metal sheet 5, the opposite surfaces 10, 11 of the fins 4, as well as the bars 6, ₂ O ₃ ) in order to increase the conversion layer 13. The anodic oxidation is preferably sulfuric or chromic anodization. The results are shown in Figs.

If the matrix 2 is assembled from a steel component, the anodization will be replaced by a phosphatization operation.

In a third step, the conversion layer 13 is covered with the holding primer layer 14. Preferably, this step is performed by dipping the bar 6, the pin 4 and the separating metal sheet 5 in an aqueous solution of the holding primer (this step is carried out by dipping the bars 6, the fins 4 and the separating metal sheets 5 in an aqueous solution of the holding primer). Thus, the component (4, 5, 6) is coated with the holding primer (14). Alternatively, the holding primer 14 is applied to the component 4, 5, 6 by projection (the holding primer 14 is applied on the components 4, 5, 6 by projection).

The application of the holding primer 14 will be ensured to be achieved in a homogeneous manner throughout the surface in order to ensure a good adhesion of the entirety of the components 4, The results of the third step are shown in Figs. 5 and 9.

The application of the holding primer 14 is followed by an intermittent drying by heating to chemically bond the holding primer 14 to the treated surface (The application of the holding primer 14 is followed by drying punctuated by heating in order to chemically bind the holding primer 14 to the treated surfaces). The connection between the holding primer 14 and the anodized surface 13 is preferably carried out at a temperature comprised between 30 and 120 minutes, preferably between 50 and 200 < 0 > C, . In a particularly preferred manner, the anodized component (4, 5, 6) coated with the holding primer 14 is maintained at about 90 캜 for about 120 minutes.

In a fourth step, the adhesive (15) is applied only to the holding primer (14) of the separating metal sheet (5). This is accomplished by applying a film to be co-laminated to the separating metal sheet 5, or by applying the adhesive 15 to the separating metal sheet 5, by means of a doctor blade or to a sufficient and uniform thickness, May be made as an evenly deposited adhesive paste in the layer, by any other means that provides the possibility of providing the deposition of the layer. The application of the adhesive 15 is preferably carried out as much as possible with a residual thickness of about 20 to 150 microns, in order to ensure both the role of protecting the underlying separating metal sheet 5 and the role of the binder Should be observed. The result of the fourth step is shown in Fig.

The practical fact that the steps 2 to 4 in the individual components (4, 5, 6) can be carried out, a readily accessible surface is a definite advantage (the actual fact of being able to carry out the steps two to four on the individual components 4, 5, 6, the surface of which is easily accessible, is a clear advantage). Adjustment of predetermined parameters such as uniformity or thickness of the deposit facilitates by observing this method. The method according to the invention is therefore advantageously characterized from the way in which the manufacture of the surfaces of the components 4, 5 and 6 performs posteriori after assembling the stack 3.

In a fifth step, the elements (4, 5, 6) are laminated to obtain the stack (3).

The sixth step consists of an ovening phase at a temperature of 150 캜 or below of the stack 3 to cure (to polymerize) the adhesive 15. At the end of the ovening, solid and corrosion-resistant matrices (2) are obtained. For example, the annealing consists of heating and holding the stack 3 at 90 ° C for 4 hours, followed by heating and holding the stack 3 at 120 ° C for 1 hour. This may be done in an oven, press-oven, with forced convection or other similar heating methods. A device for clamping the stack 3 is preferably used to optimize the connection of the component 4, 5, 6 during the polymerization process. The clamping device may hold the component (4, 5, 6) under a constant load, for example, in excess of 100 kPa.

Then, the completed matrix (2) may be provided with a head for dispensing fluid to form a heat exchanger. The fluid dispensing head may be adhesively bonded directly to the surface of the matrix (2) with the adhesive (15).

Alternatively, the fluid dispensing head is welded to the matrix 2 via an intermediate part pre-fitted into the matrix 2 during its lamination according to the water / The heads are welded to the matrix 2 via intermediate parts nested beforehand into the matrix 2 during its stacking according to a male / female configuration). The intermediate part has the possibility of moving the weld zone sufficiently away from the matrix 2 to avoid degradation of the adhesive joint of the matrix 2 due to the high temperature prevailing during welding . In this case, the seal of the connection between the intermediate part and the matrix (2) is ensured by the elastomer based on silicon.

According to the method of assembling according to the invention, each metal component (4, 5, 6) is covered with a number of layers which act as a barrier against expansion and diffusion of corrosion sources.

According to an alternative embodiment of the invention, the specific components 4, 5, 6 of the matrix 2 are brazed and others are adhesively bonded. For example, the fluid flow of the matrix 2 with the intent of accommodating the corrosive fluid, such as seawater, is limited by the adhesively bonded components 4, 5, 6, If the pressure of use of ammonia is outside the field of use of the adhesive 15, the fluid flow of the matrix 2 intended for the fluid is limited by the brazed components 4, 5, 6 For example, fluid passages of the matrix 2 are intended to receive corrosive fluids such as sea water are delimited by adhesively bonded components 4, 5, 6, while the fluid passages of the matrix 2 are intended for fluids, (1), (2), (3), (4), (5) and (6).

To obtain this mixed assembly, at the first stage, the components (4, 5, 6) to be brazed are brazed according to the usual method for manufacturing a brazed heat exchanger. Sub-assemblies of the matrix 2 are fabricated with the entirety of these components 4, 5, 6 perceiving that the braze is only present on the surface to be brazed. After brazing, the brazed sub-assembly and the remaining component (4, 5, 6) are coated with an adhesive (15) and laminated to form the stack (3). Then, the stack 3 performs the obtention described above (step 6). The low temperature of the obing provides the possibility of not degrading the brazing performed in the first period.

According to another alternative embodiment of the present invention, the adhesively bonded / brazed mixed matrix is assembled by using low temperature brazing (melting temperature of brazing below 200 占 폚). This is achieved by first assembling the entire stack 3 with sub-assemblies of these coated with an adhesive and brazing, then obliterating the stack 3 to cure the adhesive, Lt; / RTI >

By the adhesive bonding according to the present invention, the proposed heat exchanger matrix can be applied to a corrosive environment while maintaining the required thermal performance and pressure resistance characteristics. Additionally, the method according to the present invention provides the possibility of assembling a large volume heat exchanger matrix.

Claims (15)

It should be understood that the elements 4, 5 and 6, in particular of the type of the etched plate or fins 4, the separating metal sheet 5 and the stack of bars 6, A heat exchanger metal matrix (2) characterized by a combination of stacking,
At least one portion of the component (4, 5, 6) comprises a layer (15) of a structural adhesive, preferably 20 to 150 탆 thick, based on an epoxy resin containing a corrosion inhibitor, Wherein the adhesive is loaded with 20 to 60% by weight of a thermal conductor which ensures a thermal conductivity of 2 to 5 W / m / K of the adhesive.
The method according to claim 1,
Wherein the thermal conductor of the adhesive (15) is based on metal and / or ceramic.
3. The method according to claim 1 or 2,
Wherein the corrosion inhibitor of the adhesive (15) is based on zinc oxide.
4. The method according to any one of claims 1 to 3,
The components 4, 5 and 6 are coated with a layer 14 of an adhesive holder 12, in particular a conversion layer 13 and / or an adhesive holding primer, And a heat exchanger metal matrix.
5. The method of claim 4,
Wherein the conversion layer (13) comprises 1 to 50 mu m and preferably has a thickness of 5 to 20 mu m.
The method according to claim 4 or 5,
Wherein the component (4, 5, 6) is comprised of aluminum or an aluminum alloy, and the conversion layer (13) is comprised of alumina.
7. The method according to any one of claims 1 to 6,
A portion of the component (4, 5, 6) is brazed together.
10. A matrix (2) according to any one of claims 1 to 7 and preferably at least one fluid-dispensing head (6) attached to said matrix (2) / RTI >
A method for assembling a heat exchanger metal matrix (2), characterized by the steps of:
a) providing components (4, 5, 6) of the matrix (2);
b) 20 to 60 masses of a thermal conductor based on an epoxy resin containing a corrosion inhibitor and ensuring at least a part of the components (4, 5, 6) of the adhesive has a thermal conductivity of 2 to 5 W / m / %, ≪ / RTI > applying a structural adhesive (15);
c) stacking said components (4, 5, 6) to obtain a stack (3); And
d) curing the adhesive (15) to oven the stack (3) to obtain the matrix (2).
10. The method of claim 9,
Further comprising the step of applying an adhesive holder (12) in the component (4, 5, 6) before step b).
11. The method of claim 10,
The step of applying the adhesive holder 12 may include a first step of anodizing or phosphorizing and / or dipping the component into the primer or projecting the primer to the component ), And applying a holding primer (14).
12. The method of claim 11,
(4, 5, 6) coated with a holding primer (14) at a temperature comprised between 50 and 200 ° C for a period of time comprised between 30 and 120 minutes, so as to bond the holding primer (14) ≪ / RTI > further comprising drying and heating.
13. The method according to any one of claims 9 to 12,
Step b)
I) providing the adhesive (15) as a paste and spreading the adhesive to the component by a doctor blade, or
Ii) co-lamination of the adhesive (15) to the component (5)
≪ / RTI >
14. The method according to any one of claims 9 to 13,
Said step d) comprises a first phase of holding the stack 3 at a temperature comprised between 50 and 120 ° C for a minimum period of 30 minutes, then a first phase of holding the stack 3 at a temperature of 150 to 250 ° C And a second phase of holding said stack (3) at a temperature comprising said second phase.
15. The method according to any one of claims 9 to 14,
Wherein said step d) comprises holding said stack (3) under compression at a pressure of at least 100 kPa.

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