Note: Descriptions are shown in the official language in which they were submitted.
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A SHEET FOR EXCHANGE OF HEAT OR MASS TRANSFER
BETWEEN FLUID FLOWS, A DEVICE COMPRISING SUCH A
SHEET, AND A METHOD OF MANUFACTURING THE SHEET
TECHNICAL FIELD
The present disclosure generally relates to the exchange of heat or mass
transfer between fluid flows, and in particular to a sheet for heat and/or
mass
transfer, a device comprising such a sheet, and to a method of manufacturing
such a sheet.
BACKGROUND
As in most fields of technology, manufacturers of heat exchangers and
devices for mass transfer between fluid flows strive to find cost efficient
and
simple production methods.
JP2004132589 discloses a heat exchanger which comprises corrugated
sheets. The corrugations form flow channels of the heat exchanger. Every
second channel of a sheet is an open channel and the remaining channels are
closed channels. The closed channels are obtained by adhering lids to
originally open channels of the sheet. Two such sheets are then stacked and
laminated to form a plurality of closed channels.
A disadvantage with the heat exchanger disclosed in JP2004132589 is that
the lamination of the sheets requires additional process steps. In addition to
the lamination step, a process step of surface activation of the sheets to
enable lamination may also be necessary. Moreover, adhesives are expensive
and may be hazardous to the environment. Furthermore, the lamination step
also complicates changes in the production line. Different applications may
require different sheet material which in turn may need to be laminated with
different types of adhesives. Thus, if the sheet material is changed,
considerations concerning a suitable adhesive and surface activator for that
material will also need to be taken into account.
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DE 296 20 248 U1 discloses a heat exchanger with a plurality of profiled
sheet. Each sheet comprises a plurality of open "corrugated channels", of
which each has two end points, two peaks, and a valley comprising a plurality
of corrugations.
SUMMARY
In view of the above, a general objective of the present disclosure is to
provide a sheet for exchange of heat and/or mass transfer which at least
mitigate the problems of the prior art.
Another objective is to provide a device for exchange of heat or mass
transfer.
in A third objective is to provide a method of manufacturing a sheet for
exchange of heat or mass transfer.
Hence, according to a first aspect of the present disclosure there is provided
a
sheet for exchange of heat and/or mass transfer between fluid flows, which
sheet is provided with corrugations defining open channels, wherein every
other open channel is a corrugated open channel, wherein a cross-section of
every corrugated open channel has two channel end points, and two peaks
and a valley floor between the two channel end points, wherein the two
channel end points of a corrugated open channel define the mouth of that
corrugated open channel, wherein the remaining open channels that are
intermediate each pair of corrugated open channel are intermediate open
channels, wherein corrugated open channels and intermediate open channels
have mouths in opposite directions.
An effect which may be obtainable thereby is that these sheets do not require
any adhesive for stacking them to produce a heat exchanger or a device for
mass transfer between fluid flows. Every other channel has two peaks and a
valley floor which define a corrugation of each such channel, in a sense a sub-
corrugation relative to the main corrugations defining the channels of the
sheet. By means of this structure, sheets may be stacked in a manner in which
every open channel with two peaks and a valley floor of one sheet engages an
intermediate channel, i.e. a channel between two open channels each having
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two peaks and a valley floor, of another sheet. In particular the cross-
sectional shape of each open channel having two peaks and a valley prevents
relative lateral movement of two adjacent stacked sheets. Moreover, this
structure also prevents sheets to move towards each other. Stacked sheet are
hence fixed with regards to relative movement to the sides and towards each
other. Consequently, adhesives are therefore not necessary for stacking a
plurality of sheets to form a device for the exchange of heat and/or mass
transfer between fluid flows.
Furthermore, DE 296 20 248 Ui fails to disclose corrugated open channels
in and intermediate open channels having mouths in opposite directions. An
effect obtainable thereby is that four fastening points/attachment points are
obtained for sealing each individual closed channel when several sheets are
assembled to form a device for exchange of heat and/or mass transfer.
In DE 296 20 248 Ui a number of closed channels are formed by open
corrugated channels, when the sheets are stacked; in particular five closed
channels are formed when two sheets are assembled. However, these sheets
are open relative to each other; any time a pressure difference occurs between
two sheets, each set of five closed channels are opened up, whereby mixed
fluid flow is obtained.
By means of the four fixation points that are obtained according to the first
aspect presented herein, when several such sheets are stacked, the closed
channels are engaged and interlocked such that closed fluid flow in each
closed channel may always be obtained. This interlocking result in reduced
pressure sensitivity and less local movement of the sheet is obtained.
Unmixed fluid flow in heat exchange and/or mass transfer is more efficient
than mixed fluid flow.
According to one embodiment the two peaks are located at a first distance
from a straight line extending between the channel end points and the valley
floor is located at a second distance from the straight line.
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According to one embodiment the valley floor is arranged between the two
peaks. The geometry of two peaks with a valley floor therebetween provides a
locking mechanism of two stacked sheets. Two stacked sheets can thereby
interlock such that relative lateral movement and towards movement may be
restricted.
According to one embodiment the cross-sectional shape of that section which
connects the two peaks is congruent with the cross-sectional shape of any of
the open channels which are arranged between said every other open
channel. The cross-sectional shape of an intermediate open channel, i.e. of an
open channel between two channels each having two peaks and a valley floor,
thus enables the engagement or interlocking of two stacked sheets. Every pair
of stacked sheets is hence displaced, for example by one half of a channel
width, such that a portion of an intermediate open channel is aligned with
and arranged within the section that connects two peaks.
According to one embodiment the entire section connecting a first of the
channel end points with a first of the peaks is parallel with the entire
section
connecting the valley floor with a second of the peaks.
According to one embodiment the entire section connecting a second of the
channel end points and the second of the peaks is parallel with the entire
section connecting the valley floor with the first of the peaks. The section
connecting a channel end point with a peak also defines the side wall of an
intermediate open channel. Two such sections facing each other, i.e. of two
adjacent open channels having two peaks and a valley floor, thus define the
side walls of an intermediate channel. By the provision of parallel sections
as
defined above, congruence of the cross-section of an intermediate channel
with a section which connects the two peaks may be obtained.
According to one embodiment each of said every other channel has an
essentially M-shaped cross-section.
According to one embodiment the sheet is a heat exchanger sheet.
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According to a second aspect of the present disclosure there is provided a
device for exchange of heat or mass transfer between fluid flows, comprising
a plurality of sheets according to the first aspect, which plurality of sheets
are
stacked such that the open channels of each pair of adjacent sheets define
5 fluid flow channels.
According to one embodiment the channel end points of a sheet engage a
respective valley floor of an adjacent sheet.
One embodiment comprises fluid inlets and fluid outlets, wherein each fluid
inlet is arranged to direct fluid into fluid flow channels of two adjacent
sheets
and each fluid outlet is arranged to direct fluid out from fluid flow channels
of
two adjacent sheets, wherein each fluid inlet and fluid outlet has a tapering
shape.
According to one embodiment each fluid inlet has an inlet mouth parallel to
the longitudinal extension of the fluid flow channels, wherein each inlet
mouth is arranged in level with a lateral end of a sheet, wherein each fluid
inlet extends from said lateral end towards the other lateral end of the
sheet,
and wherein each fluid inlet is tapering from the said lateral end to the
other
lateral end towards channel inlet mouths of fluid flow channels. Thereby, the
Venturi effect that may affect flow in channels closest to the inlet mouth may
be reduced such that essentially uniform fluid distribution in each fluid flow
channel may be obtained. As a consequence the fluid throughput of the
device may be increased, thus increasing the efficiency of the device.
According to one embodiment each fluid outlet has an outlet mouth parallel
to the longitudinal extension of the fluid flow channels, wherein each outlet
mouth is arranged in level with a lateral end of a sheet, wherein each fluid
outlet extends from said lateral end towards the other lateral end of the
sheet,
and wherein each fluid outlet is tapering from said lateral end to the other
lateral end towards channel outlet mouths of the fluid flow channels.
Thereby, the total pressure drop is balanced between all fluid flow channels
of a specific layer of fluid flow channels. As a consequence the fluid
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throughput of the device may be increased, thus increasing the efficiency of
the device.
According to a third aspect of the present disclosure there is provided a
method of manufacturing a sheet for exchange of heat and/or mass transfer
between fluid flows, wherein the method comprises:
a) providing a sheet blank,
b) corrugating the sheet blank to form open channels such that every
other channel has a cross-section with two channel end points and two
peaks and a valley floor between the two channel end points,
wherein the two channel end points of a corrugated open channel define
the mouth of that corrugated open channel, wherein the remaining open
channels that are intermediate each pair of corrugated open channel are
intermediate open channels, wherein corrugated open channels and
intermediate open channels have mouths in opposite directions.
According to one embodiment step a) of corrugating is performed by 1)
thermoforming or 2) by folding along fold lines. Thus, a production method
may be provided in which each sheet blank may be corrugated in a simple
manner, without having to utilise any adhesive or additional parts to obtain a
robust structure when assembling a device for exchange of heat and/or mass
transfer comprising a plurality of stacked sheets.
According to a fourth aspect of the present disclosure there is provided a
sheet for exchange of heat or mass transfer between fluid flows, which sheet
is provided with corrugations defining open channels, wherein a cross-
section of every other open channel has two channel end points, and two
peaks and a valley floor between the two channel end points.
According to one embodiment the two peaks are located at a first distance
from a straight line extending between the channel end points and the valley
floor is located at a second distance from the straight line.
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According to one embodiment the valley floor is arranged between the two
peaks. The geometry of two peaks with a valley floor therebetween provides a
locking mechanism of two stacked sheets. Two stacked sheets can thereby
interlock such that relative lateral movement and towards movement may be
restricted.
According to one embodiment the cross-sectional shape of that section which
connects the two peaks is congruent with the cross-sectional shape of any of
the open channels which are arranged between said every other open
channel.
According to one embodiment the entire section connecting a first of the
channel end points with a first of the peaks is parallel with the entire
section
connecting the valley floor with a second of the peaks.
According to one embodiment the entire section connecting a second of the
channel end points and the second of the peaks is parallel with the entire
section connecting the valley floor with the first of the peaks.
According to one embodiment each of said every other channel has an
essentially M-shaped cross-section.
According to one embodiment the sheet is a heat exchanger sheet.
According to a fifth aspect of the present disclosure there is provided a
device
for exchange of heat or mass transfer between fluid flows, comprising a
plurality of sheets according to the fourth aspect, which plurality of sheets
are
stacked such that the open channels of each pair of adjacent sheets define
fluid flow channels.
According to one embodiment the channel end points of a sheet engage a
respective valley floor of an adjacent sheet.
One embodiment comprises fluid inlets and fluid outlets, wherein each fluid
inlet is arranged to direct fluid into fluid flow channels of two adjacent
sheets
and each fluid outlet is arranged to direct fluid out from fluid flow channels
of
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two adjacent sheets, wherein each fluid inlet and fluid outlet has a tapering
shape.
According to one embodiment each fluid inlet has an inlet mouth parallel to
the longitudinal extension of the fluid flow channels, wherein each inlet
mouth is arranged in level with a lateral end of a sheet, wherein each fluid
inlet extends from said lateral end towards the other lateral end of the
sheet,
and wherein each fluid inlet is tapering from the said lateral end to the
other
lateral end towards channel inlet mouths of fluid flow channels.
According to one embodiment each fluid outlet has an outlet mouth parallel
to the longitudinal extension of the fluid flow channels, wherein each outlet
mouth is arranged in level with a lateral end of a sheet, wherein each fluid
outlet extends from said lateral end towards the other lateral end of the
sheet,
and wherein each fluid outlet is tapering from said lateral end to the other
lateral end towards channel outlet mouths of the fluid flow channels.
According to a sixth aspect of the present disclosure there is provided a
method of manufacturing a sheet for exchange of heat or mass transfer
between fluid flows, wherein the method comprises:
a) providing a sheet blank,
b) corrugating the sheet blank to form open channels such that every
other channel has a cross-section with two channel end points, and
two peaks and a valley floor between the two channel end points.
According to one embodiment step a) of corrugating is performed by 1)
thermoforming or 2) by folding along fold lines.
Generally, all terms used in the claims are to be interpreted according to
their
ordinary meaning in the technical field, unless explicitly defined otherwise
herein. All references to "a/an/the element, apparatus, component, means,
etc. are to be interpreted openly as referring to at least one instance of the
element, apparatus, component, means, etc., unless explicitly stated
otherwise.
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BRIEF DESCRIPTION OF THE DRAWINGS
The specific embodiments of the inventive concept will now be described, by
way of example, with reference to the accompanying drawings, in which:
Fig. la depicts a schematic perspective view of an example of a sheet for
exchange of heat or mass transfer;
Fig. ib depicts a portion of a cross-section of the sheet in Fig. la;
Fig. lc depicts a cross-sectional view of another example of a sheet for
exchange of heat or mass transfer;
Fig. 2 shows a perspective view of a cross-section stacked sheets for exchange
of heat or mass transfer;
Figs 3a-b schematically depicts elevated views of examples of sheet with fluid
inlets and fluid outlets;
Fig. 3c depicts a perspective view of two stacked sheets which comprises a
fluid inlet and a fluid outlet;
Fig. 4 depicts a device for exchange of heat or mass transfer, which device
comprises a plurality of sheets;
Fig. 5a depicts a variation of the device in Fig. 4, comprising channel
dividing
sheets;
Fig. 5b depicts a variation of the device in Fig. 5a;
Fig. 6 depicts a flowchart of a method of producing a sheet for exchange of
heat and/or mass transfer; and
Fig. 7 depicts a top view of an example of a sheet blank.
DETAILED DESCRIPTION
The inventive concept will now be described more fully hereinafter with
reference to the accompanying drawings, in which exemplifying
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embodiments are shown. The inventive concept may, however, be embodied
in many different forms and should not be construed as limited to the
embodiments set forth herein; rather, these embodiments are provided by
way of example so that this disclosure will be thorough and complete, and
5 will fully convey the scope of the inventive concept to those skilled in
the art.
Like numbers refer to like elements throughout the description.
Fig. 1 depicts an example of a sheet 1 for exchange of heat and/or mass
transfer. The sheet 1 has a plurality of corrugations forming a plurality of
open channels 3, 5. A pair of sheets 1 may be stacked such that closed fluid
10 flow channels are formed by the open channels 3, 5 of the stacked sheets
1. A
plurality of sheets 1 may be stacked to form a heat exchanger or a device for
mass transfer between fluid flows, or a device which has both of said
functionalities. The particular application of the sheet 1 is dependent of the
properties of the material of the sheet 1. To this end, the sheet 1 may be
made
of a material that is impermeable, permeable or semipermeable for a fluid
such as water, air or any other fluid which may be utilised in heat exchange
or
mass transfer applications.
Adjacent open channels 3 and 5 of the sheet 1 have mouths in opposite
directions. Every other open channel, open channels 3, has a corrugation.
Open channels 3 will in the following be referred to as corrugated open
channels 3. The corrugation of each corrugated open channel 3 is less
prominent than the corrugations which form the open channels 3 and 5 of the
sheet 1 and may thus be seen as a sub-corrugation relative to the open
channel-defining corrugations. The remaining open channels, i.e. open
channels 5 that are intermediate each pair of corrugated open channel 3, will
in the following be referred to as intermediate open channels 5. Intermediate
open channels 5 have a cross-sectional shape which allows them to engage
the corrugation of a corrugated open channel 5 of another sheet 1 when two
sheets 1 are stacked in a manner in which each intermediate open channel 5
of one sheet 1 is arranged in an aligned manner with a respective sub
corrugation of the other sheet 1. Thus, the corrugation of each corrugated
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open channel 3 defines means for engagement with an intermediate open
channel 5 of another sheet 1.
Fig. lb shows a cross-sectional view of a portion of the sheet 1 in Fig. la.
Each
corrugated open channel 3 has two channel end points 3a and 3h defining the
mouth of open channel 3. Between the channel end points 3a, 3h of a
corrugated open channel 3 are two peaks 3c and 3d, and a valley having a
valley floor 3e. The two peaks 3c and 3d and the valley floor 3e of a
corrugated open channel 3 define the corrugation or sub-corrugation of that
corrugated open channel 3.
It should be noted that when referring to peaks and valleys throughout this
disclosure, these features obtain their intended meaning when the sheet 1 is
in the horizontal position such that the open channels 3 and 5 extend
horizontally with the mouths of the corrugated open channels 3 facing
downwards.
The two peaks 3c, 3d are located at a first distance di from a straight line L
extending between the channel end points 3a. The valley floor 3c is located at
a second distance d2 from the line L. The first distance di differs from the
second distance d2. In particular, the first distance di is greater than the
second distance d2.
The entire section 3f connecting one of the channel end points 3a with the
first peak 3c of the two peaks 3c, 3d of a corrugated open channel 3 is
parallel
with the entire section 3h connecting the valley floor 3e with the second peak
3d of the peaks 3c, 3d. The entire section 3g connecting the other channel end
point 3h with the second peak 3d is parallel with entire section 3i connecting
the valley floor 3e with the first peak 3c. In particular, every other section
connecting two inclination-changing points of a cross-section of a corrugated
open channel 3 are parallel. Each corrugated open channel 3 thus has an
essentially M-shaped cross-section when the open channels 3, 5 are arranged
horizontally with the mouths of the corrugated open channels 3 facing
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downwards. The corrugated open channels 3 have this cross-sectional shape
along their entire longitudinal extension.
The valley floor 3e is arranged between the two peaks 3c and 3d. In a cross-
section the structure of a valley floor 3e between the two peaks 3c and 3d may
be seen as a cutout, in the sense that this specific geometry functions as a
means for receiving an intermediate channel 5 of another sheet 1. In
particular, the cross-sectional shape of that section 3g, 3h of a corrugated
open channel 3 which connects the two peaks 3c and 3d is congruent with the
cross-sectional shape of any intermediate open channel 5.
Fig. lc shows a cross-sectional view of a portion of a variation of the sheet
1 in
Fig. la. Fig. lc illustrates one of a plurality of possibilities for
alternative
channel shape design. Sheet 1' depicted in Fig. lc has a plurality of
corrugations forming open channels 3' and 5'. Every other open channel is
corrugated and is a corrugated open channel 3'. The remaining open
channels, i.e. those adjacent to a corrugated open channel 3' are, as above,
referred to as intermediate open channels 5'. As can be seen, the general
cross-sectional structure of sheet 1' is identical to that of Figs la and lb.
The
cross-section of each corrugated open channel 3' includes two channel end
points 3a' and 3b', and two peaks 3c', 3d' and a valley floor 3e' arranged
between the two channel end points 3a' and 3b'. A difference between sheet 1
and sheet 1' is that the valley floors 3e' are plane and that the intermediate
open channels 5' have a plane portion. The cross sectional shape of the
intermediate open channels 5' is congruent with the section connecting the
two peaks 3c' and 3d' of a corrugated open channel 3'.
Other variations include arrangements where sections interconnecting a
channel end point and a peak have a staircase formation. Moreover, the
corrugated open channels, as well as the intermediate channels, could be
asymmetrical.
Fig. 2 shows a perspective view of a portion of two sheets 1 that have been
stacked. The intermediate open channel 5 of the upper sheet 1 has been
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arranged in the valley and rests on the valley floor 3e defined between the
two
peaks 3c and 3d of the lower sheet 1. Fluid flow channels 11 are thus formed
by pairs of intermediate open channels 5 facing corrugated open channels 3
of the two sheets 1. The two sheets 1 are shifted to the side such that each
intermediate open channel 5 of one sheet is arranged between two peaks of a
respective corrugated open channel 3 of the other sheet. Each pair of adjacent
sheet 1 are thus staggered relative to each other such that the intermediate
channels 5 of one of the sheet 1 engage respective valley floors between two
peaks of the other sheet. The corrugations of stacked sheets may thus be
identical, simplifying the manufacturing process.
Fig. 3a schematically depicts an elevated view of two or more stacked sheets
1. Each sheet 1 may have end portions, either integrated with the sheet 1, or
end parts attached to the sheet i.These end portions or parts are typically
not
corrugated but they could however be corrugated. The end portions or parts
are arranged at each end of the open channels 3, 5, i.e. at the inlet and
outlet
to the open channels 3, 5.
When two sheets 1 are stacked, the end portions or parts of both sheets 1 are
joined, for example by means of welding, or by means of an adhesive. When
joining two end portions or parts, a portion thereof is left unsealed, forming
a
mouth, such that fluid may enter the thus created fluid inlet or exit the thus
created fluid outlet. The sealed end portions or end parts of such a pair of
sheets 1 thereby form a fluid inlet 7 and a fluid outlet 9 for that pair of
sheets
1. When two pairs of such stacked sheet 1, each pair having a fluid inlet and
a
fluid outlet, in turn are stacked, the already joined end portions or parts of
a
pair will not be joined with the already joined end portions or parts of the
other pair. Instead, the fluid flow channels defined between the two pairs of
stacked sheets 1 may function as a counter-current layer. Each fluid inlet and
each fluid outlet hence serves only one layer of fluid flow channels, i.e. one
pair of sheets.
The fluid inlet 7 is arranged to direct fluid into the fluid flow channels ii
of
two stacked sheets 1 and the fluid outlet 9 is arranged to direct fluid
exiting
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from the fluid flow channels ii of the same two stacked sheets 1. Fluid inlet
7
is thus arranged at one end of the fluid flow channels ii and fluid outlet 9
is
arranged at the other end of the fluid flow channels ii. The fluid inlet 7 and
the fluid outlet 9 both have a tapering shape.
The fluid inlet 7 has an inlet mouth 7 a for receiving a fluid flow. The fluid
inlet 7 is arranged to direct fluid received via the inlet mouth 7 a into the
fluid
flow channels ii.
The fluid inlet 7 has a distal end 7b relative to channel inlet mouths la. The
inlet mouth 7 a is parallel to the longitudinal extension of the fluid flow
channels ii. The inlet mouth 7 a may be aligned with a lateral end lc of the
sheet 1. The fluid inlet 7 extends from the lateral end lc to the other
lateral
end of the sheet id. The fluid inlet 7 is tapering from the lateral end lc
aligned
with the inlet mouth 7 a to the other lateral end id towards channel inlet
mouths la of the fluid flow channels ii.
The fluid outlet 9 has an outlet mouth 9a for dispensing fluid which has
flowed through the fluid flow channels ii. The fluid outlet 9 has a distal end
9b relative to channel outlet mouths lb. The outlet mouth 9a is parallel to
the
longitudinal extension of the fluid flow channels ii. The outlet mouth 7 a may
be aligned with a lateral end id of the sheet 1. The fluid outlet 9 extends
from
said lateral end to the other lateral end lc of the sheet 1, wherein the fluid
outlet 9 is tapering from the lateral end id aligned with the outlet mouth 9a
to the other lateral end lc towards channel outlet mouths ib of the fluid flow
channels ii.
In general, the fluid inlet should have an extension so as to be able to guide
fluid into all fluid flow channels ii of a pair of adjoined sheets 1, and the
fluid
outlet part should have an extension to be able to guide fluid out from all
the
fluid flow channels ii of a pair of adjoined sheets 1. The fluid inlets and
fluid
outlets must thus not necessarily have to extend along the entire distance
between the lateral edges of a sheet. It is sufficient that their extension in
this
direction is such that each fluid inlet extends along the channel inlet mouths
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and that each the fluid outlet extends along the channel outlet mouths of all
fluid flow channels 11 in a layer of fluid flow channels.
The height dimension of the fluid inlet 7 and the fluid outlet 9 is preferably
less than the height dimension of the fluid flow channels ii. The height
5 dimension of the fluid inlet and the fluid outlet may for example be half
the
height dimension of the fluid flow channels. Other variations of this ratio
are
of course also possible. A ratio where the fluid inlet and fluid outlet have
smaller height dimension than the fluid flow channels facilitates the flow
distribution in different directions, i.e. it facilitates counter-current flow
in a
10 device comprising a plurality of stacked sheet. In particular, different
height
dimension ratios provide different pressure drops in the two flow directions.
According to the example in Fig. 3a, the inlet mouth 7a and the outlet mouth
7b are diagonally arranged. The inlet mouth 7a and the outlet mouth 9a are
thus arranged in opposite directions. Another example of arrangement of the
15 fluid inlet 7 and fluid outlet 9 relative to the sheet 1 is depicted in
Fig. 3h.
According to this variation, the inlet mouth 7a and the outlet mouth 9a are
facing the same direction. The particular orientation of the inlet mouth
relative to the outlet mouth normally depends on the application and the
particular device for exchange of heat or mass transfer that is to be
assembled
from the sheets.
Fig. 4 depicts a cross-section of a device 13 for exchange of heat and/or mass
transfer. The device comprises a plurality of stacked sheets 1, arranged as
described hereabove. According to the example, all sheets 1 are stacked with
the same orientation, i.e. the two peaks of all corrugated open channels of
all
sheets face the same direction. The device 13 may further comprise a
structure such as a mount or a frame in which the plurality of stacked sheet
may be arranged, not shown in Fig. 4. Their mutual positions may thereby be
maintained in all directions.
The pairs of sheets 1 of the device 13 may comprise fluid inlets and fluid
outlets as described above, such that fluid that is to be subjected to heat
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exchange and/or mass transfer can flow through the device 13. The device 13
may beneficially be used as a counter-current fluid flow exchange device. The
device 13 may thus be arranged such that every other layer of fluid flow
channels ii of the device 13 may receive fluid flow in a first direction, and
the
fluid flow channels ii of the remaining layers may receive fluid flow in a
second direction opposite the first direction.
Fig. 5a depicts a portion of a cross-section of a plurality of stacked sheets
that
may be arranged in a device for heat exchange and/or mass transfer. Between
each adjacent sheet 1 is a channel dividing sheet 14. The channel dividing
sheet 14 has corrugated open channels 3" similar to those described above,
and intermediate channels 5", which according to the example also have
corrugations. All open channels 3", 5" of the channel dividing sheet 14 hence
have corrugations. Each intermediate open channel 5" has two valley floors
and a peak, and the corrugations are thus inverted relative to the two peaks
and one valley floor configuration of the corrugated open channels 3". A
channel dividing sheet 14 is adapted to be arranged between each pair of
adjacent sheets 1. The channel dividing sheets 14 act as dividing elements of
the fluid flow channels created between two adjacent sheets 1. As can be seen
in Fig. 5a, each channel Ci defined by intermediate open channels 5 and 5" of
a sheet 1 and a channel dividing sheet 14 is smaller in cross-sectional
dimension compared to the cross-sectional dimension of the remaining
channels C2 defined between an intermediate channel 5" of a channel
dividing sheet 14 and a corrugated open channel 3 of a sheet 1. Moreover,
each channel Ci is surrounded by channels C2 having greater cross-sectional
dimension than channel Ci.
Fig. 5b depicts a variation of the arrangement in Fig. 5b. In the variation in
Fig. 5b, the arrangement comprises another type of channel dividing sheet
than in Fig. 5a. Moreover, the channel dividing sheet 14 in Fig. 5b has an
undulating profile with each open channel having equal height, instead of
having an M-W profile as in Fig. 5a. Any combination of channel dividing
sheets could however be used in a device for heat exchange and/or mass
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transfer, depending on the particular application and the desired fluid flow
characteristics.
Channel dividing sheet 14' comprises planar sections 14'a and corrugated
sections 141D. A corrugated section 141D is provided between each pair of
planar section 14'a. The channel dividing sheet 14' is arranged to be
sandwiched between two adjacent sheets 1. Each corrugated section 14'a is
congruent with an intermediate open channel 5 and with a valley of a sheet 1.
The width of each planar section 14'a is dimensioned such that each
corrugated section 14'a can be arranged sandwiched between an intermediate
open channel 5 of one sheet 1 and a valley of another sheet 1. The planar
sections 14'a provide the channel dividing property of the channel dividing
sheet 14', and each planar section 14'a is arranged to divide a fluid flow
channel formed by two adjacent sheets 1, in particular between an
intermediate open channel 5 and a corrugated open channel 3. The planar
sections 14'a divide the fluid flow channels into channels C3 and C4. The
cross-sectional dimension of channels C3 and C4 are determined by
dimensioning the planar sections 14'a and the corrugated sections 14'b in a
suitable manner depending on the particular application and desired
specifications of the heat exchange and/or mass transfer. As an alternative to
the arrangement shown in Fig. 5b a device for exchange of heat and/or mass
transfer may for example comprise channel dividing sheets 14' only in
combination with sheets 1.
According to one variation the channel dividing sheet may be a sheet blank or
a deformable sheet. When the sheet blank or deformable sheet is arranged
between two sheets 1, the sheet blank or deformable sheet is shaped by the
two sheets. In particular, the sheet blank or deformable sheet, which
initially
may be essentially shapeless or it may not have an intentionally shaped
design, can obtain a similar shape as for example channel dividing sheet 14',
i.e. the material of the channel dividing sheet folds where an intermediate
channel of a sheet 1 is arranged between two peaks of another sheet 1 with the
channel dividing sheet being arranged therebetween. The sheet blank or
deformable sheet may thus in production of a device for heat exchange
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and/or mass transfer be placed on top of a sheet 1, wherein another sheet 1 is
placed on top of the sheet blank or deformable sheet such that the sheet
blank or deformable sheet folds in those locations where an intermediate
channel of one sheet are arranged between two peaks of the other sheet. The
sheet blank or deformable sheet is thereby stretched or tightened to form
planar sections between the folded or corrugated sections. A channel dividing
sheet is thereby created.
An example of suitable material for a sheet blank or deformable sheet may be
a membrane material, for example Gore-Tex or a cellulose-based material.
The configurations illustrated in Figs 5a and 5b are advantageous in for
example heat exchange systems utilising liquids as heat transfer medium for
influencing the temperature of a gas. A liquid generally has a greater heat
capacity than gas, and the amount of liquid may thus in general be smaller
than the amount of gas to obtain a heat equilibrium condition between the
two fluids. By means of the configurations shown in Fig. 5a and Fig. 5b, and
any variation thereof, a more efficient heat exchanger may be obtained. A
device comprising a configuration as shown in Figs 5a and 5b may thus utilise
a greater amount of its fluid transfer capacity for the gas which is to have
its
temperature altered. Moreover, the size of the device utilising this
arrangement may be reduced.
An example of an application for the arrangement shown in Fig. 5a is an oil
cooling device, where the device comprising the configuration of sheets 1 and
14 may be adapted such that oil may flow through channels Ci and a gas may
flow through channels C2.
With reference to Figs 6 and 7, a method of manufacturing a sheet such as
sheet 1 will be described in more detail. In a step a) a sheet blank is
provided.
In a step b) the sheet blank is corrugated to form open channels 3, 5 such
that
every other channel has a cross-section with two channel end points, and two
peaks and a valley floor between the two channel end points.
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In Fig. 7 one example of a sheet blank 15 is shown. The sheet blank 15
comprises a plurality of fold lines 17 and 19. Fold lines 17 create the two
peaks
and the valley floor of a corrugated open channel 3 when the fold lines 17
have been folded. Fold lines 19 create intermediate channels 5 when the fold
lines 19 have been folded. Step b) of corrugating may for this variation thus
involve folding the sheet blank 15 along the fold lines 17 and 19. The fold
lines
17 and 19 may for example be created by creasing.
As an alternative to providing fold lines to create a sheet blank, the step of
corrugating may be performed by for example thermoforming or any other
method of corrugating a sheet blank. Another alternative is to extrude the
shape of a corrugated sheet directly, or to extrude the entire device
comprising a plurality of sheets.
In a further optional step, a plurality of sheets may be stacked in a
staggered
manner. The distal ends of each pair of adjacent fluid inlet and fluid outlet
may be attached to each other to thereby form distal end walls for both the
fluid inlet and fluid outlet to thereby create fluid flow guides. In case the
fluid
inlet and fluid outlet are integrated with the sheet blank, the fluid inlet
and
the fluid outlet may be corrugated in step b). Typically, the corrugations of
the fluid inlet and fluid outlet differ from that of the open channels 3 and
5.
The cross-sectional shape of the fluid inlet and fluid outlet thus normally
differs from that of the open channels 3 and 5.
The sheet 1 and its variations presented herein may be rigid or flexible.
According to one variation, the sheet is flexible along the corrugation lines,
e.g. fold lines in case the corrugations have been folded during
manufacturing. Device 13 may thereby be flexible in the sense that it may be
deformed when a pressure is applied from any side along its periphery. This
is beneficial in that the volume of the device may be reduced during
transportation. The device may thus be deformed for transportation, and
thereafter receive its original shape for installation.
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As previously noted, the sheet, including the channel dividing sheet, may be
made of impermeable, permeable, or semi-permeable material. The device
may be formed of sheets all having the same properties. All sheets may thus
be impermeable, permeable or semipermeable. Alternatively, the device may
5 comprise a combination of sheets with different permeability properties.
For
example a subset of sheets may be permeable and another subset of sheets
may be impermeable. Every other sheet may for example be permeable and
the remaining sheets may be impermeable.
The sheets, including the channel dividing sheets, may for example be made
10 of metal, for example stainless steel, aluminium, copper or any other
metal
suitable for heat transfer, plastic such as PE, PP, PET, PS, PPS,
Polycarbonate, nylon, semi-permeable membranes, for example PEMs like
Nafion, or any other suitable material for heat exchange or mass transfer
applications, for example carbon foam and porous sheets. It is also envisaged
15 that the sheet may comprise a mixture of different materials.
The inventive concept has mainly been described above with reference to a
few examples. However, as is readily appreciated by a person skilled in the
art, other embodiments than the ones disclosed above are equally possible
within the scope of the inventive concept, as defined by the appended claims.
