U.S. patent application number 14/917382 was filed with the patent office on 2016-07-28 for bonded heat exchanger matrix and corresponding bonding method.
The applicant listed for this patent is FIVES CRYO. Invention is credited to Gaetan Joel Bergin, Salima Bouti, Thierry Mazet.
Application Number | 20160216039 14/917382 |
Document ID | / |
Family ID | 50478475 |
Filed Date | 2016-07-28 |
United States Patent
Application |
20160216039 |
Kind Code |
A1 |
Bergin; Gaetan Joel ; et
al. |
July 28, 2016 |
BONDED HEAT EXCHANGER MATRIX AND CORRESPONDING BONDING METHOD
Abstract
A heat exchanger metal matrix has a stack of components in which
at least one of the components is bound by an adhesive layer based
on an epoxide resin containing a corrosion inhibitor, and the
adhesive layer is loaded with 20 to 60% by mass of a heat conductor
so that a heat conductivity of the adhesive layer is in a range of
2 to 5 W/m/K. The heat exchanger metal matrix may be applied to
corrosive environments, notably marine environments.
Inventors: |
Bergin; Gaetan Joel;
(Poussay, FR) ; Mazet; Thierry; (Nancy, FR)
; Bouti; Salima; (Nancy, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FIVES CRYO |
Golbey |
|
FR |
|
|
Family ID: |
50478475 |
Appl. No.: |
14/917382 |
Filed: |
August 22, 2014 |
PCT Filed: |
August 22, 2014 |
PCT NO: |
PCT/EP2014/067878 |
371 Date: |
March 8, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28F 2275/02 20130101;
F28F 3/08 20130101; F25J 2290/42 20130101; F28D 9/0062 20130101;
F25J 2290/44 20130101; F25J 5/002 20130101; F28D 9/0093 20130101;
F28F 2275/025 20130101 |
International
Class: |
F28D 9/00 20060101
F28D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 9, 2013 |
FR |
13 58657 |
Claims
1. A heat exchanger metal matrix comprising: a stack of components
wherein at least one said components is bound by an adhesive layer
based on an epoxide resin containing a corrosion inhibitor, and the
adhesive layer is loaded with 20 to 60% by mass of a heat conductor
so that a heat conductivity of the adhesive layer is in a range of
2 to 5 W/m/K.
2. The heat exchanger metal matrix according to claim 1, the heat
conductor of the adhesive layer is based on a metal and/or a
ceramic.
3. The heat exchanger metal matrix according to claim 1, the
corrosion inhibitor of the adhesive layer is based on zinc
oxides.
4. The heat exchanger metal matrix according to claim 1, wherein
the components are coated with an adhesive holder.
5. The heat exchanger metal matrix according to claim 4, wherein
the adhesive holder comprises a conversion layer having a thickness
between 1 and 50 .mu.m.
6. The heat exchanger metal matrix according to claim 5, wherein
the components are made of an aluminium or an aluminium alloy, and
the conversion layer is made of an alumina.
7. The matrix according to claim 1, wherein a part of the
components is brazed.
8. A heat exchanger comprising the matrix according to claim 1.
9. A method for assembling a heat exchanger metal matrix
comprising: a) providing components of the heat exchanger metal
matrix; b) applying a structural adhesive (15) based on an epoxide
resin containing a corrosion inhibitor and the structural adhesive
is loaded with 20 to 60% by mass of a heat conductor so that a heat
conductivity of the structural adhesive is in a range of 2 to 5
W/m/K on at least a part of the components; c) stacking the
components so as to obtain a stack; and d) ovening the stack as to
cure said structural adhesive and thereby obtain the heat exchanger
metal matrix.
10. The method according to claim 9, further comprising: applying
an adhesive holder on the components before applying the structural
adhesive.
11. The method according to claim 10, wherein b) applying the
adhesive holder comprises: anodizing or phosphorizing; and/or
applying a holding primer by dipping the components in a primer or
projecting a primer on the components.
12. The method according to claim 11, further comprising: drying
and heating the components covered with the holding primer at a
temperature between 50 and 200.degree. C. for a period between 30
and 120 mins so as to bind the holding primer to the
components.
13. The method according to claim 9, wherein b) applying the
adhesive holder comprises: i) providing the structural adhesive as
a paste and spreading the paste of the structural adhesive out on
the components by a doctor blade, or ii) co-laminating the
structural adhesive on the components.
14. The method according to claim 9, wherein d) ovening the stack
comprises: maintaining the stack at a temperature between 50 and
120.degree. C. for a minimum period of 30 minutes followed by
maintaining the stack at a temperature between 150 and 250.degree.
C. for a minimum period of one hour.
15. The method according to claim 9, wherein d) ovening the stack
comprises: maintaining the stack under compression at a pressure
above 100 kPa.
16. The heat exchanger metal matrix according to claim 1, wherein
the stack of the components is a stack of etched plates or fins,
separating metal sheets and bars, or a combination of both types of
stacking.
17. The heat exchanger metal matrix according to claim 1, wherein
the adhesive layer has a thickness between 20 and 150 .mu.m.
18. The heat exchanger metal matrix according to claim 4, wherein
the adhesive holder is a conversion layer and/or a layer of an
adhesive holding primer.
19. The heat exchanger metal matrix according to claim 5, wherein
the thickness of the conversion layer is between 5 and 20
.mu.m.
20. The heat exchanger according to claim 8, further comprising: at
least one fluid-dispensing head adhered to the matrix with said
adhesive layer.
Description
[0001] The invention relates to the field of metal heat exchangers,
notably in aluminium, of the type with etched plates, of the type
with separating metal sheets, bars and fins or including a
combination of both of these types.
[0002] These heat exchangers are currently used in methods for
separating gases from air and for liquefying natural gas, because
of their very good energy performance properties, of very low
temperature mechanical strength and lightness.
[0003] In a known way, the matrix of these heat exchangers is
assembled by brazing and their fluid dispensing heads are welded on
the brazed matrix.
[0004] The thereby formed heat exchangers are of a purely metal
nature and sensitive to corrosion. Their field of application is
therefore limited to clean and not very corrosive environments.
Notably, they support neither sea water nor a marine
atmosphere.
[0005] The origin of this incompatibility stems from diffusion
phenomena involved at the interface of the constitutive components
of the exchanger and of the brazing, which induce metallurgical
modifications of the initial material. After cooling, the presence
of intermetallic precipitates is assumed to be one of the major
causes of the occurrence of corrosion pits, following the formation
of electrochemical cells favoring etching of the adjacent metal
base.
[0006] Anticorrosion coatings exist, but their application on these
types of equipment remains a problem. The anticorrosion coating may
either be applied on the individual components of the matrix before
the assembling and brazing step, or on the finished matrix after
brazing.
[0007] The first method has the disadvantage of only being able of
using anticorrosion coatings remaining stable at brazing
temperatures and not perturbing the brazing. The second method does
not give the possibility of uniformly depositing the anticorrosion
coating and in the whole of the brazed matrix since the latter
includes many crevices with access difficulties.
[0008] An object of the invention is therefore to make a heat
exchanger metal matrix which better resists to corrosion while
remaining solid and a good heat conductor. Such a matrix should
notably be adapted to marine applications.
[0009] According to the invention, this object 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, preferably with a thickness comprised between 20 and 150
.mu.m, of a structural adhesive based on epoxy resin containing a
corrosion inhibitor and loaded with 20 to 60% by mass of a heat
conductor ensuring a heat conductivity of the adhesive from 2 to 5
W/m/K.
[0010] By binding at least one portion of the components of the
matrix by means of said adhesive, it is possible to do without the
brazing and the traditional filler metal which is sensitive to
corrosion. By the selected adhesive formulation, the matrix is
protected against corrosion and retains its mechanical and thermal
performances.
[0011] The matrix according to the invention finds a particularly
advantageous application in heat exchangers placed in a corrosive
environment, notably in a marine medium, whether the heat
exchangers are immersed in water or in a marine atmosphere.
[0012] According to preferred embodiments, the matrix according to
the invention comprises one, several or all of the following
features, in any technically possible combinations: [0013] the heat
conductor of the adhesive is based on metal and/or ceramic; [0014]
the corrosion inhibitor of the adhesive is based on zinc oxides;
[0015] the components are coated with an adhesive holder, notably a
conversion layer and/or a layer of adhesive holding primer; [0016]
the conversion layer has a thickness comprised between 1 and 50
.mu.m and preferably comprised between 5 and 20 .mu.m; [0017] the
components are in aluminium or an aluminium alloy, and the
conversion layer is in alumina; [0018] a portion of the components
are brazed together.
[0019] The present invention also relates to a heat exchanger
including a matrix as defined above, and preferably at least one
head for dispensing fluid adhered to the matrix, notably with said
adhesive.
[0020] Another object of the invention is to achieve a method for
assembling a heat exchanger metal matrix adapted to corrosive
environments. According to the invention, this object is achieved
by a method for assembling a heat exchanger metal matrix,
characterized by the steps: [0021] a) providing the components of
the matrix; [0022] b) depositing a structural adhesive based on
epoxy resin containing a corrosion inhibitor and loaded with 20 to
60% by mass of a heat conductor ensuring a heat conductivity of the
adhesive from 2 to 5 W/m/K on at least one portion of the
components; [0023] c) stacking the components so as to obtain a
stack; and [0024] d) ovening the stack so as to harden said
adhesive and to thereby obtain the matrix.
[0025] According to preferred embodiments, the method according to
the invention comprises one, several or all of the following
features, in any technically possible combinations: [0026] the step
consisting of applying an adhesive holder on the components before
step b); [0027] the adhesive holder application 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; [0028] the step consisting
of drying and heating the components covered with holding primer at
a temperature comprised between 50 and 200.degree. C. for a period
comprised between 30 and 120 mins, so as to bind the holding primer
to the component. [0029] step b) comprises: [0030] i) providing the
adhesive as a paste and spreading it out on the component by means
of a doctor blade, or [0031] ii) co-lamination of the adhesive on
the component; [0032] step d) comprises a first phase for
maintaining the stack at a temperature comprised between 50 and
120.degree. C. for a minimum period of thirty minutes followed by a
second phase for maintaining the stack at a temperature comprised
between 150 and 250.degree. C. for a minimum duration of one hour.
[0033] step d) comprises the phase for maintaining the stack under
compression at a pressure above 100 kPa.
[0034] The invention consists, except for the arrangements
discussed above, in a certain number of other arrangements which
will be more explicitly discussed hereafter as regards exemplary
embodiments described with reference to the appended drawings, but
which are by no means limiting. Among the drawings:
[0035] FIG. 1 is a perspective and exploded view illustration of a
matrix during stacking according to an exemplary embodiment of the
invention;
[0036] FIG. 2 is a detail 7 of the matrix of FIG. 1 showing the
adhesive bonding of the components of the matrix;
[0037] FIGS. 3 to 6 illustrate the treatment of a separating metal
sheet of the matrix of FIG. 1 according to the assembling method of
the invention; and
[0038] FIGS. 7 to 9 illustrate the treatment of a fin of the matrix
of FIG. 1 according to the assembling method of the invention.
[0039] Subsequently, in order to simplify the description of the
invention, reference will be made to a heat exchanger matrix with
separating metal sheets, bars and fins, being aware that the
invention also applies to an exchanger with etched plates, or to an
exchanger comprising a combination of separating metal sheets, bars
and fins and etched plates. Further, an aluminium matrix will be
described subsequently. Nevertheless, the invention also covers
matrices consisting of other metals, such as notably steel.
[0040] With reference to FIG. 1, a stack of a matrix 2 being made
may be schematically seen as illustrated. In a known way, the
matrix 2 consists of a stack 3 of components, i.e. fins 4,
separating metal sheet 5, and aluminium bars 6.
[0041] The particularity of the matrix 2 is visible in FIG. 2. An
enlarged illustration of the area 7 of the matrix 2 indicated in
FIG. 1 is distinguished therein. A fin 4 is located between two
separating metal sheets 5 and bound to the latter. Both separating
metal sheets 5 have two opposite faces 8 and 9, and the fin 4 has
two opposite faces 10 and 11.
[0042] According to the invention, the separating metal sheets 5
and the fin 4 are covered on their two opposite faces 8, 9 and 10,
11 with an adhesive holder 12. The adhesive holder 12 consists of
two layers, i.e. a conversion layer 13 extending over the faces 8,
9, 10, 11, and an adhesive holding primer layer 14 deposited on the
conversion layer 13. The conversion layer 13 consists of alumina.
The primer layer 14 consists of a resin from the family of epoxide
resins in which are integrated corrosion inhibitors, for example
zinc salts. The conversion layer 13 has a thickness I comprised
between 1 and 50 .mu.m and preferably comprised between 5 and 20
.mu.m. The primer layer 14 preferably has a thickness d of a few
micrometers.
[0043] An adhesive layer 15 deposited on both opposite faces 8, 9
of the separating metal sheets 5 ensures the connection between the
separating metal sheets 5 and the fin 4. Preferably, the thickness
e of the adhesive layer 15 is comprised between 20 and 100
.mu.m.
[0044] The adhesive 15 is a structural adhesive from the family of
epoxide resins. The adhesive 15 contains corrosion inhibiting
elements, for example zinc salts or oxides. The adhesive 15 is also
loaded with 20 to 60% by mass of additional elements which
substantially increase its heat conductivity, for example of metal
or ceramic origin. Thus, the heat conductivity of the adhesive 15
is located between 2 and 5 W/m/K.
[0045] The method for assembling the matrix 2 will now be
described, with reference to FIGS. 3 to 9.
[0046] In a first step, the separating metal sheets 5 are made in
aluminium, an example of which is shown in FIG. 3, the fins 4, an
example of which is shown in FIG. 7, and the bars 6 of the matrix
2.
[0047] In a second step, the opposite faces 8, 9 of the separating
metal sheets 5, the opposite faces 10, 11 of the fins 4, as well as
the bars 6 are anodized in order to grow conversion layers 13 in
alumina (Al.sub.2O.sub.3). The anodization is preferably sulfuric
or chromic anodization. The result is illustrated in FIGS. 4 and
8.
[0048] If the matrix 2 is assembled from steel components, the
anodization will then be replaced with a phosphatization
operation.
[0049] In a third step, the conversion layers 13 are covered with
the holding primer layers 14. Preferably, 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 components
4, 5, 6 are coated with holding primer 14. In an alternative, the
holding primer 14 is applied on the components 4, 5, 6 by
projection.
[0050] It will be ensured that the application of the holding
primer 14 is accomplished in a homogenous way on the whole of the
surfaces, in order to subsequently guarantee good adherence of the
whole of the components 4, 5, 6. The result of the third step is
illustrated in FIGS. 5 and 9.
[0051] 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 surfaces 13 is preferably
obtained by a hot air treatment carried out at a temperature
comprised between 50 and 200.degree. C., this for a period which
preferably ranges between 30 and 120 mins. In a particularly
preferred way, the anodized components 4, 5, 6 coated with the
holding primer 14 are maintained at about 90.degree. C. for about
120 mins.
[0052] In a fourth step, the adhesive 15 is only applied on the
holding primer 14 of the separating metal sheets 5. This may be
made as an adhesive paste uniformly deposited in layers by means of
a doctor blade in order to end up with a sufficient and uniform
thickness, or else by applying a film which will be co-laminated on
the separating metal sheets 5, or by any other means giving the
possibility of providing the deposit of adhesive 15 on the
separating metal sheets 5. The application of the adhesive 15
should observe as much as possible a residual thickness of about 20
to 150 microns in order to both ensure the role of a binder and the
role for protecting the underlying separating metal sheet 5. The
result of the fourth step is illustrated in FIG. 6.
[0053] 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. The control of
predetermined parameters like the thickness or the uniformity of
the deposit is facilitated by observing this methodology. The
method according to the invention is thus advantageously
distinguished from methods in which the preparation of the surfaces
of the components 4, 5, 6 is accomplished a posteriori after
assembling the stack 3.
[0054] In a fifth step, the components 4, 5, 6 are stacked in order
to obtain the stack 3. The sixth step consists of an ovening phase
at a temperature below 150.degree. C. of the stack 3 in order to
cure (polymerize) the adhesive 15. At the end of the ovening, a
solid and corrosion-resistant matrix 2 is obtained. The ovening for
example consists in heating and maintaining the stack 3 at
90.degree. C. for four hours, followed by heating and maintaining
the stack 3 at 120.degree. C. for one hour. This may be carried out
in a press-oven, in an oven with forced convection or any other
equivalent heating method. A device for clamping the stack 3 is
preferably used in order to optimize the connection of the
components 4, 5, 6 during the polymerization process. The clamping
device may for example maintain the components 4, 5, 6 under a
constant load exceeding 100 kPa.
[0055] The completed matrix 2 may then be provided with heads for
dispensing fluid in order to form a heat exchanger. The fluid
dispensing heads may be directly adhesively bonded on the surface
of the matrix 2 with said adhesive 15.
[0056] Alternatively, the fluid dispensing 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. Said
intermediate parts give the possibility of moving the welding area
sufficiently away from the matrix 2 in order to avoid degradation
of the adhesive joints of the matrix 2 by the high temperatures
prevailing during welding. In this case, the seal of the connection
between the intermediate part and the matrix 2 is ensured by an
elastomer based on silicone.
[0057] By means of the assembling method according to the
invention, each metal component 4, 5, 6 is covered with multiple
layers which act as barriers to diffusion and to propagation of
corrosion sources.
[0058] According to an alternative embodiment of the invention,
certain components 4, 5, 6 of the matrix 2 are brazed and others
adhesively bonded. For example, fluid passages of the matrix 2
intended to receive the corrosive fluid such as sea water are
delimited by adhesively bonded components 4, 5, 6, while the fluid
passages of the matrix 2 intended for fluids, for which the
pressure of use is outside the field of use of the adhesive 15, for
example ammonia, are delimited by brazed components 4, 5, 6.
[0059] In order to obtain this mixed assembly, in a first phase,
the components 4, 5, 6 having to be brazed are brazed according to
the usual method for manufacturing a brazed heat exchanger.
Sub-assemblies of the matrix 2 are made with the whole of these
components 4, 5, 6, being aware that the brazing is only present on
the surfaces which have to be brazed. After brazing, the brazed
sub-assemblies and the remaining components 4, 5, 6 are coated with
adhesive 15 and stacked for forming the stack 3. The stack 3 then
undergoes ovening described above (step six). The low temperature
of the ovening gives the possibility of not degrading the brazing
carried out in a first phase.
[0060] According to another alternative embodiment of the
invention, an adhesively bonded/brazed mixed matrix is assembled by
using low temperature brazing (melting temperature of the brazing
below 200.degree. C.). This gives the possibility of first
assembling the whole stack 3 with its sub-assemblies coated with
adhesive and brazing, and then ovening said stack 3 so as to
thereby cure the adhesive and at the same time merge the
brazing.
[0061] By means of the adhesive bonding according to the invention,
the heat exchanger matrix proposed may be applied in corrosive
environments while retaining the required heat performance and
pressure resistance properties. Further, the method according to
the invention gives the possibility of assembling heat exchanger
matrices of a large volume.
* * * * *