U.S. patent application number 10/585601 was filed with the patent office on 2009-07-23 for heat exchanger and related exchange module.
Invention is credited to Sylvain Benezech, Pierre-Xavier Bussonnet, Michel Claudel, Florent Noel.
Application Number | 20090183862 10/585601 |
Document ID | / |
Family ID | 34684927 |
Filed Date | 2009-07-23 |
United States Patent
Application |
20090183862 |
Kind Code |
A1 |
Benezech; Sylvain ; et
al. |
July 23, 2009 |
Heat exchanger and related exchange module
Abstract
A heat exchanger, includes modules defining a first path for a
first fluid, each having two metal sheets forming between them a
network of channels which are located in parallel with each other
from the fluidic point of view, each channel interposed between two
neighbouring channels of the network being, over the whole of its
developed length, adjacent to these two neighbouring channels from
which it is isolated by two respective weld lines connecting the
two metal sheets; a second path for a second fluid is defined
between the modules; and an overall variation in the passage
cross-section over the length of at least one of the paths with
continuity of profiles of the channels.
Inventors: |
Benezech; Sylvain; (Beaune,
FR) ; Bussonnet; Pierre-Xavier; (Dracy Le Fort,
FR) ; Claudel; Michel; (Sarrebourg, FR) ;
Noel; Florent; (Harskirchen, FR) |
Correspondence
Address: |
GREER, BURNS & CRAIN
300 S WACKER DR, 25TH FLOOR
CHICAGO
IL
60606
US
|
Family ID: |
34684927 |
Appl. No.: |
10/585601 |
Filed: |
January 12, 2005 |
PCT Filed: |
January 12, 2005 |
PCT NO: |
PCT/FR2005/000068 |
371 Date: |
July 11, 2006 |
Current U.S.
Class: |
165/170 |
Current CPC
Class: |
F28D 9/0031 20130101;
F28F 13/08 20130101; F28F 3/14 20130101 |
Class at
Publication: |
165/170 |
International
Class: |
F28F 3/12 20060101
F28F003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 12, 2004 |
FR |
0400210 |
Claims
1. A heat exchanger comprising: modules defining a first path for a
first fluid, each comprising two metal sheets forming between them
a network of channels which are located in parallel with each other
from the fluidic point of view, each channel interposed between two
neighbouring channels of the network being, over the whole of its
developed length, adjacent to these two neighbouring channels from
which it is isolated by two respective weld lines connecting the
two metal sheets; a second path for a second fluid is defined
between the modules; and an overall variation in a passage
cross-section over the length of at least one of the paths with
continuity of profiles of the channels.
2. A heat exchanger according to claim 1, characterised in that the
pitch between the neighbouring weld lines varies progressively over
at least part of the length of the channels of one module.
3. A heat exchanger according to claim 1, characterised in that the
inflation of the metal sheets of a module varies progressively over
at least part of the length of the channels.
4. A heat exchanger according to claim 1, characterised in that the
pitch between neighbouring weld lines varies from one channel to
the other of a module.
5. A heat exchanger according to claim 1, characterised in that the
inflation of the metal sheets of a module varies from one channel
to another.
6. A heat exchanger according to claim 1, characterised in that the
arrangement of the modules in relation to each other produces an
overall variation in the passage cross-section over the length of
the second path.
7. A heat exchanger according to claim 1, characterised in that the
overall variation in the cross-section of one of the paths is in
the same direction as a variation in the flow rate of gas in this
path intended for a phase change process.
8. A heat exchanger according to claim 1, characterised in that the
modules are in parallel planes.
9. A heat exchanger according to claim 1, characterised in that the
modules are in convergent planes.
10. A heat exchanger according to claim 1, characterised in that
the modules have longitudinal edges forming an angle with each
other, each being almost parallel to a respective outside weld
line.
11. A heat exchange module comprising two metal sheets which
between them form a network of channels located in parallel to each
other from a fluidic point of view, each channel interposed between
two neighbouring channels of the network being adjacent over its
whole developed length to these two neighbouring channels from
which it is isolated by two respective weld lines joining the two
metal sheets, and wherein an overall variation in the passage
cross-section is defined by the channels with continuity of profile
of the channels.
12. A heat exchange module according to claim 11, characterised in
that the pitch between neighbouring weld lines varies progressively
over at least part of the length of the channels.
13. A heat exchange module according to claim 11, characterised in
that the inflation of the metal sheets varies progressively over at
least part of the length of the channels.
14. A heat exchange module according to claim 11, characterised in
that the pitch between the neighbouring weld lines varies from one
channel the other.
15. A heat exchange module according to claim 11, characterised in
that the inflation of the metal sheets varies from one channel to
the other.
16. A heat exchange module according to claim 11, characterised in
that it comprises longitudinal edges each forming an angle with the
other, each being almost parallel to a respective outside line of
weld.
Description
[0001] This invention relates to a heat exchanger and a heat
exchange module intended to form part of such an exchanger.
[0002] A heat exchanger is known from WO 98/16786 in which modules
define a first path for a first fluid, each one comprising two
metal sheets defining between them a network of channels arranged
mutually in parallel from the fluidic point of view. Each channel
interposed between two neighbouring channels of the network is,
over the whole of its developed length, adjacent to these two
neighbouring channels, from which it is isolated by two respective
weld lines joining the two metal sheets. A second path for a second
fluid is defined between the modules, in the internal volume of a
casing enclosing the modules.
[0003] According to this document, the modules are manufactured
from two flat sheets, which are joined together by weld lines
comprising the above-mentioned lines isolating the neighbouring
channels from each other, then a pressurised liquid is introduced
between the metal sheets, producing an inflation of the two metal
sheets between the weld lines, thereby to form the channels. The
channels of a same module are in parallel from a fluidic point of
view between two distribution zones common to all the channels of a
same module, themselves connected to connecting boxes.
[0004] During the hydroforming step, i.e. the above-mentioned
inflation step, the inflation in the distribution zones is limited
so that when in operation the second fluid more easily enters into
pseudo-channels formed between the neighbouring modules in the
troughs between the successive inflated zones. Apart from these
zones of limited inflation, the profile of the channels is
continuous and even uniform. Thus the fluid passage cross-sections
are only modified locally at the inlet and outlet. The transition
between the modified passage cross-section zone and the zone with a
constant passage cross-section along the channels, is abrupt and
localised.
[0005] WO 01/07 854 describes an improvement according to which the
channels are U-shaped instead of rectilinear. In a variant
illustrated in FIG. 25 of this document, a localised modification
is shown of the passage cross-sections with an abrupt transition
between the "normal" zone and the modified zone acting as the inlet
and outlet of the first and second fluid in the first and second
path, respectively.
[0006] DE-A1-19639115 describes a heat transfer element in the form
of a plate constituted by two metal sheets defining between them
channels for an exchange fluid. In embodiments described with
reference to FIGS. 4 and 5, each channel has a general U-shaped
configuration which is bifurcated two times successively, such that
the passage cross-section varies progressively in a ratio of 1 to 4
from one end to the other of the branched channel. Each channel
thus folded back on itself and branched, occupies a rectangular
space; the rectangular spaces being contiguous to each other by
their adjacent lengths. The purpose of this arrangement is to
reduce the speed of the internal fluid when it has almost completed
its exchange process, for improved calorific exchange in the zones
where the two exchange fluids exhibit a small temperature
difference between them. The application indicated is a cooling
element for high-temperature batteries for electric vehicles.
[0007] Such an exchanger is particularly complex to produce and its
flow rate is very limited.
[0008] The object of this invention is to propose a heat exchanger
which without significant extra expense allows the progress of the
flow rates of at least one of the exchange fluids to be controlled,
in particular when this fluid undergoes at least a partial change
of state, for example condensation, while flowing.
[0009] Another object of the invention is to produce a heat
exchanger with low pressure losses distributed in a controlled
manner.
[0010] Another object of the invention is to propose a heat
exchange module which can be part of such an exchanger.
[0011] According to the invention, the heat exchanger in which
modules define a first path for a first fluid and each module
comprises two metal sheets forming between them a network of
channels which are in parallel with each other from the fluidic
point of view, wherein each channel which is interposed between two
neighbouring channels of the network is, over the whole of its
developed length, adjacent to these two neighbouring channels and
is separated therefrom by two respective weld lines joining the two
metal sheets, and a second path for a second fluid is defined
between the modules, is characterised by an overall variation in
passage cross-section along at least one of the paths, with the
channels having continuity of profile.
[0012] It has been found according to the invention that a
structure of the type described in WO 98/16 786 or WO 01/07 854,
i.e. with channels isolated from each other which are adjacent over
their whole developed length, is particularly suitable for
implementation of overall variations in passage cross-section along
at least one of the paths.
[0013] By "overall" variation is understood a variation other than
the localised path-end variations described above in relation to
the prior art, and other than the local variations due for example
to the fact that the second exchange fluid, if circulating
transversally to the channels, experiences for example a reduction
in passage cross-section each time it passes an inflated part of
one of the two adjacent modules.
[0014] By "continuity of profile of the channels" is indicated that
the variations in passage cross-section are not due to profile
discontinuities such as cross-sectional variations due to abrupt
widening or narrowing, variations due to bifurcation of a single
channel into two channels.
[0015] The overall variations in cross-section may be obtained
according to the invention by channels of different hydraulic
diameters, by channels the hydraulic diameter of which varies
progressively from one end to the other, and/or by a relative
arrangement of the modules which varies the hydraulic diameter
between the modules for the second fluid and/or etc.
[0016] The hydraulic diameter of a passage for a fluid is the
diameter of a theoretical cylindrical tube offering the same flow
resistance as the passage in question having a profile other than a
circular cylinder.
[0017] According to a second aspect of the invention, the heat
exchange module comprising two metal sheets forming between them a
network of channels with continuous profile arranged in parallel to
each other from a fluidic point of view, each channel interposed
between two neighbouring channels of the network being adjacent
over the whole of its developed length to these two neighbouring
channels from which it is isolated respectively by two weld lines
joining the two metal sheets; is characterised by an overall
variation in the passage section defined by these channels with
continuity of profile of the channels.
[0018] Other features and advantages of the invention will become
apparent in the following description, which relates to
non-limitative examples.
[0019] In the attached drawings:
[0020] FIG. 1 is a perspective view, with a cut-out, of a
vertical-flow parallel current plate heat exchanger;
[0021] FIG. 2 is a perspective view of a cross-current plate heat
exchanger, the flow in the modules--or plates--being vertical;
[0022] FIG. 3 is a perspective view of a plate condenser with the
plates arranged in vertical planes and rising gas flow.
[0023] FIG. 4 diagrammatically illustrates, two modules according
to a first embodiment of the invention, in a perspective view.
[0024] FIGS. 5 to 8 are views similar to a portion of FIG. 4 but
illustrating four other embodiments of the invention;
[0025] FIG. 9 is a diagrammatic sectional view of a heat exchanger
module according to yet another embodiment, during the course of
its manufacture by hydroforming in a die;
[0026] FIG. 10 is a view of a variant in order to produce a
half-die;
[0027] FIG. 11 is a perspective view of a heat exchange module
according to yet another embodiment;
[0028] FIGS. 12 and 13 are elevational views of two embodiments for
a bundle of modules according to FIG. 11;
[0029] FIG. 14 diagrammatically illustrates a perspective view of a
bundle obtained with modules according to a modification of FIG.
11; and
[0030] FIG. 15 is a view of another embodiment of a bundle of
modules for a heat exchanger according to the invention.
[0031] Generally, in the interests of clarity, all the drawings of
this application are very diagrammatic, the number of channels in a
module being markedly lower than would be found in most real
situations, and the metal sheet thickness is represented as unduly
large.
[0032] FIGS. 1 to 3 very diagrammatically show different types of
heat exchangers by way of illustration, to enable a better
understanding of the invention.
[0033] In the example shown in FIG. 1, the heat exchanger comprises
a casing 1 with a rectangular profile with respect to the vertical
axis, containing a stack of heat exchange modules 2 in the general
form of plates, extending along vertical planes. Each module 2 is
essentially made up of two metal sheets 3, which are welded
together along vertical weld lines 4, and which are inflated
between these weld lines 4 to define between them the vertical
channels 6.
[0034] Each channel extends with a continuous profile over the
whole height of the module 2. All the channels 6 open at each upper
and respective lower end, into an upper connection chamber 7
defined in an upper connecting box 8 or respectively in a lower
connection chamber 9 defined in a lower connecting box 11. Thus the
channels 6 together constitute a first exchange path for a first
fluid and this first exchange path may, in operation, be connected
by the connecting boxes 8 and 11 to an external circuit for this
first fluid. The sealed connection of the channels 6 to the
chambers 7 and 9 is provided by bars 12 of a suitable shape which
are inserted between the ends of the modules 2 and together form a
base for the connecting box 8 or 11 respectively. The channels 6
are thus in parallel from a fluidic point of view with each other
between the two connection chambers 7 and 9. Each channel 6 apart
from the two end channels of the network of channels of each module
is adjacent over its whole developed length to two neighbouring
channels, while being isolated from these two neighbouring channels
by a respective weld line 4 which is continuous over the whole
developed length of the channel. In the case illustrated here where
the channels are rectilinear, the developed length is the same as
the overall length. In other cases where the channels are curved
and for example have a U-shape as in WO 0107854, the developed
length is of course very different to the bulk length.
[0035] A second path for a second exchange fluid is defined between
the modules 2. The inlet and the outlet in this second path are by
means of second connecting boxes 13 and 14 located on the side wall
of the casing 1 to enable their internal chambers 16 and 17
respectively to communicate with the gaps 18 between the edges of
modules 2, on the side of the ends 19 of the bars 12 which faces
away from the connection chamber 7 or 9. In the example of the
connecting box 13, its periphery is leak-tightly welded to
periphery 22 of a rectangular opening formed in casing 1. One side
21 of the periphery 22 is formed by the aligned ends 19.
[0036] Thus a second exchange fluid flows between the connecting
boxes 13 and 14, passing through a second exchange path constituted
by the internal space of casing 1 located between modules 2.
[0037] In the example shown, the lateral connecting box 13 is
located in the upper part close to the upper connecting box 8 for
the first path, while the lateral connecting box 14 is located on
the lower part of casing 1 close to the lower connecting box 11 of
the first path. The second fluid enters laterally between the
modules, flows between the modules parallel to the channels 6, then
exits laterally by the other connecting box. Each of these two
fluids may flow upwards or downwards according to the application.
The name "counter-current exchanger" describes an exchanger with
parallel currents in which the two fluids flow in opposite
directions, one upwards and the other downwards in this example.
The name "co-current exchanger" describes an exchanger in which the
two fluids flow not only parallel, but also in the same
direction.
[0038] The example shown in FIG. 2 will only be described in so far
as it differs from that shown in FIG. 1.
[0039] In this example, the lateral connecting boxes for the second
path 13 and 14 completely cover two opposite sides of the casing 1;
these sides then being entirely open such that the second fluid
flows in a horizontal direction parallel to the planes of modules
2. Such an exchanger where the two fluids flow in different
directions is known as a "cross-current" exchanger.
[0040] The example in FIG. 3 will only be described in so far as it
differs from that shown in FIG. 2. In this cross-current exchanger,
the channels 6 are oriented horizontally; the modules 2 still being
in vertical planes. The path of the first fluid is therefore
directed horizontally. In contrast, the connecting boxes for the
second fluid 13 and 14 are placed under and over the case 1 such
that the direction of flow of the second fluid is vertical between
the modules 2. In the example more particularly shown in FIG. 3,
this concerns a condenser. The lower connecting box 13 comprises an
inlet 23 for a gas and the upper connecting box 4 comprises an
outlet 24 for the residual gas part from the inlet flow 23. When
this flow 23 passes between the modules 2, the channels 6 of which
have cooling fluid such as, for example, cold water, passing
through them, the condensable part of the second fluid forms
droplets which fall back into a bottom 26 of the connecting box 13
and are then evacuated through a lower outlet for liquid 27.
[0041] In such a condenser, the second fluid has a volume flow rate
which decreases from the inlet 23 to the outlet 24, as the initial
volume of gas decreases to the extent that a part of the gas
condenses.
[0042] Consequently, if the passage cross-section of the second
path is approximately the same for the whole length of this second
path between the inlet connecting box 13 and the outlet connecting
box 14, the speed of flow will decrease. If this is an appropriate
speed at the inlet of the second path, it will be too slow for
effective exchange near the outlet. If, on the other hand, the
speed is appropriate in the region of the outlet, it will be too
high at the inlet and the gas will have a tendency to carry
droplets along with it towards the outlet, contrary to the
separation effect sought.
[0043] This example of a condenser has been chosen to clearly
demonstrate the advantages of a different passage cross-section in
different zones of the same path, but other examples can be
envisaged, in particular in an evaporator, or also to adapt the
speeds in the meaning of an optimisation of the result obtained, in
particular in terms of heat exchanges.
[0044] In the example shown in FIG. 4, each module 102 comprises
channels 6.sub.a, 6.sub.b, 6.sub.c, 6.sub.d, having different
hydraulic diameters.
[0045] In the example of FIG. 4, the pitch of the weld lines 4,
i.e. the distance between the successive weld lines 4 is equal to a
constant called P.sub.o. The difference in hydraulic diameter
between neighbouring channels is obtained by a difference in
inflation of the metal sheets 3 in each zone defining a channel;
channels 6.sub.a to 6.sub.d having inflation amplitudes G.sub.a to
G.sub.d respectively, which increase from one edge to the other of
the module 102. The profile and consequently the hydraulic diameter
of each channel 6.sub.a, 6.sub.b, 6.sub.c, or 6.sub.d are constant
over the whole length of this channel.
[0046] When two modules 102 as described are placed side-by-side in
parallel planes P, with the modules of the same hydraulic diameter
placed facing each other, the available hydraulic diameter in the
second path 28 between these modules 102 in a direction
perpendicular to that of channels 6.sub.a to 6.sub.d varies overall
from one end to the other of the second path. If for example the
second path is ascending, in the configuration shown where the
channels have a hydraulic diameter increasing from bottom to top,
the hydraulic diameter of the second path decreases from its
beginning to its end. This corresponds to the desired
characteristics in the condenser in FIG. 3 according to the
explanations given above.
[0047] In the example shown in FIG. 5, which will only be described
with respect to its differences in relation to the example in FIG.
4, each module 202 comprises groups of channels having identical
hydraulic diameters; however these diameters being different from
one group to another. In the diagrammatic representation of FIG. 5,
there are two groups each of two channels, namely the lower group
of channels 6.sub.a, 6.sub.b with an identical relatively small
hydraulic diameter, and the upper group of channels 6.sub.c and
6.sub.d with an identical relatively large hydraulic diameter. Here
once again, the differences in diameter are the result of different
levels of inflation with an identical pitch P.sub.o. Consequently,
the second path 28 comprises a first hydraulic diameter between the
channels 6.sub.a and 6.sub.b of the neighbouring modules 202, and a
second smaller hydraulic diameter between the neighbouring channels
6.sub.c and 6.sub.d.
[0048] In the example in FIG. 6, which will only be described with
respect to its differences in relation to the example in FIG. 5,
between the two groups of channels 6.sub.a, 6.sub.b and 6.sub.c,
6.sub.d there is an intermediate channel 6.sub.e with an inflation
of 6.sub.e which has an intermediate value between the lower value
of channels 6.sub.a and 6.sub.b and the higher value of channels
6.sub.c and 6.sub.d. Consequently, the hydraulic diameter 6.sub.e
is intermediate between that of channels 6.sub.a and 6.sub.b, and
the larger value of channels 6.sub.c and 6.sub.d. Furthermore, the
second path 28 has between the channels 6.sub.e of the neighbouring
modules 302, an intermediate value between the larger one defined
between the channels 6.sub.a and 6.sub.b and the smaller one
defined between the channels 6.sub.c and 6.sub.d.
[0049] In all the examples described up to this point the pitch
P.sub.o between the weld lines 4 was the same for all the weld
lines for one module and for all of the modules. In the example
shown in FIG. 7, the inflations G.sub.o are the same for all the
channels of all the modules 402. In contrast, the channels of a
network comprise a first group of channels 6.sub.g and a second
group of channels 6.sub.h. The pitch P.sub.g between two weld lines
defining between them a channel 6.sub.g is greater than the pitch
P.sub.h between two weld lines defining between them a channel
6.sub.h. In this example, the hydraulic diameter of the path 28
decreases when the pitch of the weld lines decreases.
[0050] The example shown in FIG. 8 combines the pitch and inflation
variations. There are four channels 6.sub.j, 6.sub.k, 6.sub.m,
6.sub.n with pitches P.sub.j to P.sub.n which increase regularly
and inflations G.sub.j to G.sub.n which also increase regularly
from bottom to top of each module 502.
[0051] FIG. 9 illustrates the hydroforming stage to produce a
module with four groups of channels 6.sub.p, 6.sub.q 6.sub.r
6.sub.s, having different hydraulic diameters resulting at least in
part from different levels of inflation. Before injection of the
hydroforming liquid, the flat blank of the module, comprising at
this stage two flat metal sheets welded together, for example by
laser welding, along the weld lines such as 4 in the previous
figures, between dies 31, 32 which between them define a cavity
with working surfaces 33.sub.p, 33.sub.q, 33.sub.r, 33.sub.s, and
34.sub.p, 34.sub.q, 34.sub.r, 34.sub.s respectively, between which
the module blank is laid and which have between each pair of
surfaces, a distance corresponding to the required inflation in
each area respectively. FIG. 9 shows the result obtained after
differentiated inflation of the different channels following
separation of the working surfaces between which they are
located.
[0052] FIG. 10 illustrates less expensive tooling in which each die
(only the lower die 31 is shown) has a flat working surface 33
corresponding to the maximum inflation envisaged, and separate
shims 36.sub.p, 36.sub.q, 36.sub.s to define the zones where less
inflation is required.
[0053] For the upper die 32 (not shown in FIG. 10), the shims
should be fixed below the working surface of the die to avoid them
moving by gravity before the hydroforming stage. For the lower die,
it is also desirable for the shims to be fixed.
[0054] FIGS. 9 and 10 also illustrate that the invention enables
the hydraulic diameters to be varied in a first direction, for
example in the direction of increase, for example between the
groups 6.sub.p and 6.sub.q or 6.sub.q and 6.sub.r, then in a second
direction, here the direction of decrease between the group 6.sub.r
and 6.sub.s, when this is required to optimise the exchanger.
[0055] In all the examples described with reference to FIGS. 4 to
8, the weld lines 4 of a module are mutually parallel and the
hydraulic diameter of a channel is constant over its whole
length.
[0056] In the example represented in FIG. 11, the weld lines 604 of
a module 602 are all convergent; in this example towards a single
point situated beyond one of the ends of the module. In other
words, the neighbouring weld lines between them form a relatively
narrow angle, labelled as A in FIG. 11. Thus, the pitch between
successive weld lines increases from one end to the other of each
channel, as does the hydraulic diameter of the channel. Such a
module has an isosceles trapezoidal general shape, with oblique
longitudinal sides 37 which are approximately parallel to the two
outside weld lines 604 of the network of channels.
[0057] Such a module is useful in order to produce a condenser in a
configuration according to FIG. 1 or FIG. 2; i.e. with vertical
channels. If the large end of the channels is facing upwards, the
fluid to be condensed may follow a descending path within the
channels where it encounters a hydraulic diameter which decreases
in relation to the reduction in volume of the fluid by
condensation. The second fluid, for example water, passes between
the modules, or may form a bath between the modules. With the same
arrangement of modules, an ascending-flow evaporator can also be
produced; the first fluid encountering increasing hydraulic
diameters as its volume increases due to evaporation.
[0058] Such a module can also be arranged with the large end of the
channels downwards in order to produce, for example, a reflux
condenser; i.e. as described above with reference to FIG. 3, with
an increasing evaporation flow and droplets forming which flow back
to the base and into a collector.
[0059] The inflation of the channels may be constant along each
channel, or alternatively may increase from the narrower end to the
wider end of each channel.
[0060] FIG. 12 shows an elevation view of a bundle of modules 602
with channels where the inflation increases from bottom to top and
where the modules are in parallel vertical planes. In the example
shown in FIG. 13, modules 602 identical to those in FIG. 12 are
placed in planes which converge towards a point located above the
narrow end of the channels so as to reduce the hydraulic diameter
of the second path on the side where the ends of the channels are
narrow, in relation to the embodiment in FIG. 12.
[0061] FIG. 14 shows the bundle very diagrammatically when the
inflation is constant along each channel of the modules according
to FIG. 11. The bundle has the shape of a hexahedron in which the
two opposite faces are isosceles trapeziums in parallel planes. A
casing for such a bundle typically has a corresponding shape, with
two opposing parallel faces in the shape of an isosceles trapezium
and two rectangular faces joining the oblique sides of the
trapeziums.
[0062] If, moreover, the inflations of the channels are variable as
illustrated in FIGS. 12 and 13, the bundle takes the general shape
of a truncated pyramid, i.e. the two trapezoidal faces are inclined
in relation to each other and the two other lateral faces also
become trapezoidal. The casing typically has a corresponding
shape.
[0063] In the example shown in FIG. 15, the modules 702 have
channels which are all identical with the same widths and the same
inflations over the whole of their length. These modules are
arranged in a fan-shape in relation to each other, thus in oblique
planes with respect to each other, converging beyond one end of the
channels such that the hydraulic diameter of the second path,
assumed to be for co-current or counter-current, varies from one
end to the other.
[0064] In a way which is not shown, it is also possible to position
the modules in relation to each other in a fan shape by relative
pivoting about an axis parallel to the weld lines, thus to the
longitudinal direction of the channels, in order to produce a
variable hydraulic diameter of the second path when the exchanger
is the cross-current type.
[0065] In the examples in FIGS. 1 to 3, the modules 2 are offset in
relation to each other in their own plane such that the peaks of
undulation of one module are located opposite the troughs of
undulation of the two neighbouring modules. This arrangement
favours circulation in the second path following a transverse
direction to the channels, whether for a cross-current exchanger
(FIGS. 2 and 3) or for the entry of the second fluid by a side
opening and the exit of the second fluid by another side opening in
the case of a parallel-current exchanger (FIG. 1). However, in
order to simplify the illustrations, all the examples given with
reference to FIGS. 4 to 8, 14 and 15 represent another possible
arrangement, with the undulations of two neighbouring modules
facing each other peak-to-peak and trough-to-trough. This is simply
by way of illustration, and the invention is equally applicable
with an offset arrangement, for example the one in FIGS. 1 to
3.
[0066] The invention is particularly applicable with the following
dimensions: [0067] developed length of channels: 0.5 to 10 m [0068]
width of the network of channels: 0.15 to 2 m [0069] pitch sequence
of modules: 8 to 105 mm [0070] pitch sequence of weld lines: 10 to
100 mm [0071] inflation of channels: 5 to 80 mm measured inside the
channels.
[0072] The metal sheets are typically of stainless steel of a
thickness of a few tenths of a millimetre (no upper limit at 10/10)
with the understanding that a thin sheet is preferable for thermal
exchange but that the pressure differences between the two fluids
and the thermal stresses must also be taken into account.
[0073] Of course, the invention is not limited to the examples
described and represented. The means of varying the hydraulic
diameter described may be combined in very many ways.
[0074] It is conceivable to produce channels which have a constant
hydraulic diameter over one part of their length and a
progressively variable hydraulic diameter over another part of
their length.
[0075] The exchangers described with reference to FIGS. 1 to 3 are
not in any way limitative. For example, if the exchange modules are
arranged without offsetting between them, thus with the undulations
facing peak-to-peak, it is possible to locally reduce the inflation
of the channels in the zones envisaged for the lateral introduction
of the second fluid, in a similar manner to that described with
reference to FIG. 25 of WO 01/07 854. When the second fluid is a
bath, the casing may be unnecessary.
[0076] The invention is compatible with non-rectilinear channels,
for example the U-shaped channels of WO 01/07 854.
[0077] With respect to the example in FIGS. 11 to 14, it is also
possible to have modules in which: [0078] the inflation varies
progressively along each channel; [0079] the pitch between weld
lines, on the other hand, is constant.
* * * * *