The invention relates to a heat transfer device with channels for heatabsorbing
media and channels for heat-emitting media, at least one of
the channels having a textile structure with compressed and noncompressed
regions. Whilst the compressed regions are disposed in the
transition regions between the channels in order to improve the heat
transfer to or across the channel wall, the non-compressed regions are
disposed in the flow regions of the channels. This construction enables
a large heat transfer to the heat transfer surface with simultaneously
good heat conduction from the heat transfer surface to the separating
surface. The invention likewise relates to heat exchangers with heat
transfer devices of this type.
In the case of the phenomenon of heat transfer, surface increase is of
central importance.
For example the following objectives are in the forefront:
e equalisation of greatly different heat transfer coefficients, by an
increased surface being made available for heat transfer in the
medium on the side with the lower heat transfer coefficient (e.g.
air),
r increase in the power density of heat exchangers by means of a
more compact construction,
m increase in the heat transfer in the case of boiling processes,
r optimisation of the heat- and material transport kinetics in the
case of sorption processes/chemical reactions or catalytic
processes,
0 assistance to capillary transport processes, and
m humidifying and dehumidifying of air and other gases.
According to the application, the increase in power density (corresponds
to reduction in constructional volume and/or the material use), the
reduction in the operating temperature differences, the reduction in
pressure loss, the increase in yield due to reduced cycle times or a
combination of these values is of interest.
For heat exchangers with large specific surfaces, nowadays above all
attached or soldered lamellar heat exchangers, consisting of copper
tubes and attached copper-, aluminium- or stainless steel lamellae and
also flat tube-based aluminium coolers, in which folded lamellae with
extruded fluid channels are soldered, are of importance.
In order to achieve an energy-efficient, component-compact and
material-saving heat transfer in flowing media, it is of central
importance to achieve a high volume-specific surface and also as large
as possible and as integral as possible a contact surface between the
separating surface and the surface increase. At the same time, it is
important to design the paths of the heat conduction through the
surface increase structure to be as short and direct as possible. By
means of corresponding slots, bulges, undulations etc. in the surface
increase structure, it is attempted to achieve as high a surface-specific
heat transfer as possible without disproportionately increasing the
pressure loss to be overcome. The values which are achieved here by
the currently available heat oxchangers are compiled in table 1.
I / surface area ( the fluid structure 1 I
Table 1:
pressed I
type volume-specific of contacting
lamellae (flat,
contact surface for
[mZ/m31
1,250
stamped)
A further possibility for the production of large specific surfaces and
integral contacting to the separating surface are represented by metallic
short fibre structures. These are piled onto each other, compressed and
subsequently soldered or sintered. By varying the fibre length and
diameter, a variation in density and porosity is achievable. They reach
volume-specific surfaces of 8,000 - 10,000 m2/m3 and volume-specific
separating surfaces between the two media in the range of 100 m2/m3.
For use in flowing media, the non-defined orientation and arrangement
of the fibres is however disadvantageous.
lm2/m31
55
1
lamellae
metallic short fibres
Combination of fibre mats and tubes likewise represents a possibility for
increasing surfaces.
In DE 27 02 337 Al, the combination of flextble tubes and fibre mats is
described, in order to produce e.g. surface heating units. The focus of
8,000 - 10,000
folded/ undulated 65 integral (soldered)
100
1,340
soldered/ sintered
the invention resides however on the flexible tube layout, the fabric is
defined merely as carrier structure and not as specifically designed heat
transfer structure.
In DE 31 24 379 A l , a wire mesh is described, which is processed either
by soldering to tubes or by weaving throuihflowable tubes to form a
heat exchanger. The fabric i-, thereby structured uniformly, a geometric
design is effected by processing, at points, of fairly thick wires or by
folding the fabric mat. A dirt-repellent coating by Teflon is mentioned.
Wire spacings and diameters are not specified in more detail.
Similarly thereto, a fabric with woven-in copper tubes is described in DE
34 27 251 Al. The structure is proposed for use as low-temperature
heating element. The connection technique, wire spacings and
diameters are not specified in more detail.
In DE 10 2006 022 629 Al, a heat exchange device for heat exchange
between media is proposed, with which the heat exchange device is
supplied, the media not coming in contact with each other and at least
one tube being provided for one medium. The invention is distinguished
by the tubes being integrated in a woven structure.
In WO 98131976 Al, a heat exchanger element is described, in the case
of which the heat transfer is achieved by bar ribs which are
perpendicular in the flow and at an equal spacing from each other. As
suitable dimensions, the bar cross-section is indicated at 4 mm2 and
the ratio of bar diameterllength at 0.3. In the description for
implementation, fabric and knitted fabric are mentioned as preferred
material and described both for the wall and for the production of the
bar structure. Thus, the bars are also conceivable, e.g. in the form of
loops.
In US 3,313,343 A, a surface increase is described by means of a folded,
unstructured, diagonally woven, metal sieve. The metal fabric is placed
between two flat plates guiding the fluid so that fluid channels are
formed by the folded fabric.
In WO 2012/141793 Al, a general hierarchically structured surface
increase for heat exchanger3 with flat plates is described. The surface
increase forms channels in the flow direction of the fluid and becomes
thicker with increasing spacing relative to the plate.
In WO 2011/137522 Al, a method for the production of heat
exchangers made of discs is described, which discs were cut from a
block of layered fabric. The surfaces of these discs are sealed by coating
processes so that media separation is achieved without additional
separating elements (plates, foils).
The technical problem underlying the present invention resides in nonoptimal
adaptation of available surface increases to the respective
problem and construction situation. The requirement for high heat
transfer power with low operating temperature differences and low
pressure losses with low material use in a small constructional space
has to date not been fulfilled adequately by the solutions known from
the state of the art. Hence, there is an increased consumption of
material and energy for overcoming the pressure losses.
It was hence the object of the present invention to provide devices for
heat transfer which fulfil in fact these requirements for reduced
material- and energy consumption with simultaneously high heat
transfer power and, at the same time, can be produced in a simple and
economic manl-~er.
This object is achieved by the heat transfer device having the features of
claim 1 and the heat exchanger having the features of claim 19. In
claim 21, uses according to the invention are indicated. The further
dependent claims reveal advantageous developments.
According to the invention, a heat transfer device is provided, which has
at least one channel for a heat-absorbing medium and at least one
channel for a heat-emitting medium. At least one of these channels
thereby has a textile structure at least in regions, the textile structure
having compressed regions at regular spacings, the compressed regions
of the textile structure being disposed in the transition region between
at least one channel for a heat-absorbing medium and at least one
channel for a heat-emitting medium [or the production of a thermal
contact between these channels. Furthermore, non-compressed regions
of the textile structure are disposed in the flow region of at least one
channel.
Within the scope of the present invention, there should be understood
by the term channel, also those regions which have a channel-like
configuration but, because of the filling with a solid material, e.g. PCM,
no longer represent a channel or, as e.g. in the case of planar heating
structures, are open towards the surroundings.
The textiles structures used according to the invention enable very large
heat transfer surfaces. These are orientated such that a high heat
transfer to the heat transfer surface and good heat conduction from the
heat transfer surface to the separating surface is achieved at the same
time. In the case of permeated heat transfer devices, the flow is thereby
disturbed only as far as it serves to improve the heat transfer.
With the heat transfer device according to the invention, the advantage
is associated that, with simultaneous use of material and constructional
volume, less energy need be consumed for the same heat transfer. With
the same use of energy and constructional volume, less material need
be used for the heat transfer device according to the invention and, with
the same use of energy and material, the constructional volume can be
reduced.
A preferred embodiment provides that the channels for the heatabsorbing
media are separated from the channels for the heat-emitting
media by a separating wall, in particular a metal sheet, a film, a
membrane or the outer surface of a tube or hose.
It is thereby preferred that the compressed regions in the transition
region of the channels are connected integrally to the separating wall at
least in regions, in particular by gluing, soldering, welding, sintering or
casting.
A further embodiment according to the invention provides that the
textile structure at the compressed regions has a coating which is
impermeable for the media.
A further embodiment according to the invention relates to a heat
transfer device for separation of adjacent channels, in at least one
channel, an expandable hose or tube which is impermeable for the
media is integrated and/or, around at least one channel, a shrinkable
hose or tube which is impermeable for the media is disposed, which
enable contacting to the textile structure by widening and/or shrinking.
The textile structure disposed in at least one channel can preferably be
permeated, at least in regions, by a fluid for heat exchange. In a further
variant, the textile structure can be embedded, at least in regions, in a
latently heat-storing, sorptive or catalytic stationary medium.
A fur.ther preferred embodiment provides that the textile structures of
channels adjacent to each other have different wire lengths and/or
spacings of the wires in the separating surface plane.
The non-compressed regions can thereby preferably be varied such that
the flow resistance in the channel is adjustable via the wire lengths,
wire diameters and/or spacings of the wires. This can be used in
particular for the purpose of producing diagonally approached
structures with secondary channels situated between. In comparison
with the inflow rate, the flow rate through the textiles structure with
which the diagonal structu~zsa re permeated is reduced. When flowing
around the textile structures according to the invention with low fibre-,
yarn or wire diameters, large heat transfers can in fact be achieved with
low flow rates. Thus, the more slowly permeated diagonal structures
lead to an advantageous reduced pressure loss with simultaneous
transfer density or to an advantageous higher transfer density with the
same pressure loss. The diagonally approached region can include in
general compressed and non-compressed textile structures and also
possibly separated heat-transfer media which flow in the plane of this
region.
Such an arrangement of fabric structures is possible in particular if the
structures are produced to be planar, i.e. with a small throughflow
depth. A fold in these planar structures into the desired form can be
effected in a second production process. Production of a secondary,
structure-free channel by means of corresponding folding of the
structure is not restricted to textile structures. This can also be
achieved by other permeable heat transfer structures, in particular
lamellae, sponges, foams, sintered fibre structures or homogeneous
textile structures. Hence, a comparable advantageous heat transfer
behaviour can be achieved.
The textile structure thereby preferably consists of wires, technical
fibres or yarns hereof with a preferred diameter of 10 pm to 2 urn,
particularly preferably of 80 pm to 300 pm. The wires, technical fibres
or yarns hereof thereby have, in flow direction, preferably a spacing of
20 pm to 20 mm, preferably of 40 pm to 10 mm and particularly
preferably of 100 pm to 4 mm.
The wires, technical fibres or yarns hereof are preferably selected from
the group consisting of
e metallic materials and the alloys thereof, in particular copper,
aluminium or stainless steel,
e carbon-containing materials, in particular carbon fibres, activated
carbon fibres,
e glass- and ceramic fibres,
e polymer materials, in particular polypropylene (PP), polyethylene
(PE), polyamide (PA), polyether ketones (PEK), polyester (PET) and
e composite materials hereof.
The textile structure preferably has intrinsic rigidity which enables a
self-supporting construction of the heat exchanger.
Preferably, the textile structure consists of a woven, knitted or warpknitted
structure or combinations hereof.
Furthermore, it is preferred that the fabric structure used was coated
galvanically with a solder and, by melting the solder, the intrinsic
stability of the structure and the integral connection at the node points
of the wires is implemented to each other and to the separating surface.
I
A preferred embodiment provides that, in the heat transfer device,
lighting elements, in particular optical fibres or elements having LEDs,
are integrated, preferably in the form of incorporated wires, fibres or
yarns.
Likewise it is possible that, in the heat transfer device, at least one
heating wire, in particular made of copper, copper-nickel alloys, nickelchromium
alloys, constantan, manganin, nickel-iron alloys or kanthal,
is integrated.
According to the invention, a heat exchanger is likewise provided, which
comprises a heat transfer device according to the invention, as was
described previously. The heat exchanger thereby preferably concerns a
plate heat exchanger, a tubular heat exchanger, a tubular lamellar heat
exchanger, a flat tube lamellar heat exchanger or a coaxial heat
exchanger.
The heat transfer devices according to the invention are used in
particular in heat transfer to/from air or other gaseous media (e.g.
recirculation cooler, exhaust gas heat exchanger, convectors, ventilation
devices, oil coolers, etc.), in heat transfer to/from water or other liquid
media, in applications with phase change (evaporation, condensation,
solid/liquid) and also in combination with sorption materials or
catalytic coatings.
The subject according to the invention is intended to be explained in
more detail with reference to the subsequent Figures without wishing to
restrict said subject to the specific embodiments shown here.
Fig. 1 shows the textile structure according to the invention with
reference to two embodiments (Fig. la and lb) in the flat and in the
folded state.
Fig. 2 shows a first flat embodiment (Fig. 2a) and a second tubular
embodiment (Fig. 2b) of the heat transfer device according to the
invention.
Fig. 3 shows a variant of a heat transfer device according to the
invention, with a combination of various textile structures (Fig. 3a) and
in combination with a collector (Fig. 3b).
Fig. 4 shows a variant of the textile structure with different wire
spacings (Fig. 4a) and wire lengths (Fig. 4b) in the permeated region.
Fig. 5 shows a variant according to the invention of a coaxial heat
exchanger using the previously (Fig. 4b) shown elements.
Fig. 6 shows a further embodiment of a textile structure according to
the invention.
Fig. 7 shows a further embodiment of the textile structure according to
the invention.
Fig. 8 shows examples of structured surfaces according to the invention.
In Fig. 1, a flat fabric made of wires is illustrated on the left-hand side
(Fig. la), which fabric has non-compressed regions (1) and more
narrowly manufactured wire regions (2). By folding this structure, a
spacing structure which configures a flow channel and two top surfaces
is produced. Two examples of such a spacing structure are illustrated
in Fig. la in the central part and the lower part. Whilst in the central
part of the Figure, the wires of the non-compressed region are disposed
diagonally, in the lower part of Fig. la, the wires are disposed parallel to
each other and perpendicular to the formed wall surface. In Fig. lb, a
comparable embodiment is illustrated, in which however the more
narrowly manufactured regions (2) turn out to be larger relative to the
regions with long wire spacings (1). In the case of the embodiment
shown in Fig. lc, the folding leads to tapering secondary channels. The
non-compressed regions situated between the secondary channels of the
textile structure are permeated at a lower normal speed compared with
the inflow speed such that a lower pressure loss is achieved. The
formed wall surfaces can be connected to a separating wall by one of the
joining methods mentioned above or can be coated directly
impermeably.
In the flat embodiment shown in Fig. 2a, the above-illustrated folded
structure on the wall surfaces is contacted to a separating surface (3)
which was configured as a metal sheet or foil via soldered joints (4). On
the other side of the separating wall, the same textile structure is
situated, rotated by 90°, so that this element can be used for example in
a counter-current plate heat exchanger.
In the tubular embodiment shown in Fig. 2b, the compressed regions of
the textile structure (2) form a hose-like form which is applied on a
separating wall configured by tubes from outside. The non-compressed
regions (1) thus form the surface-increasing structure in the region
between the tubes. This structure can be permeated for example
perpendicular to the tubes and wires for heat exchange.
As indicated in Fig. 3a, the dimensioning of the flow structures can be
adapted flexibly to the corresponding media or flow conditions separated
via separating surfaces (7). Thus, it is conceivable, for example, that the
dimensions of the wire spacings and heights are different for different
sides of the heat exchanger.
One possibility for use hereof is shown in the embodiment in Fig. 3b.
Here, the one side of the separating surface (8) is completely surrounded
so that permeable flat pipes are configured, to which the one medium is
distributed via a collector (9). The other medium flows perpendicularly
through the other folded structures situated between the flat tubes. As
an advantage relative to conventional flat tubes, the stabilising spacing
structures permit use of very thin separating walls. Because of the
folding technique however and also with the textile manufacturing
technique, defined structured regions of different densities can also be
produced in one medium (Fig. 4a), e.g. in order to compensate for
unequal speed distributions in the inflowing medium, to control
specifically temperature gradients of the second medium or to meet
complex geometric requirements. As shown in Fig. 4b, the top surfaces
need not thereby necessarily be parallel.
In Fig. 5, a coaxial heat exchanger with a circumferential outer shell 6 is
illustrated, the individual segments of the tubular cross-section being
filled with the textile structure according to the invention. Here, the
non-compressed regions 1 and the separating wall 2, on which the
compressed regions are situated, can be detected. The segments are
thereby permeated with one or the other medium alternately so that one
medium flows in and the other medium out of the image plane.
It is also possible, from a technical manufacturing point of view, to
produce flow structures which are produced in one manufacturing step
(see Fig. 6), the non-compressed wires (1) can thereby be disposed
diagonally relative to each other. The connection to the top surface (5)
can be achieved for example by knitting processes. As a result of the
diagonal position of the wires, increased intrinsic stability of the
structure is achieved. The reduction in manufacturing steps is an
attractive feature here also, however, the thermal masses must be
considered.
In Fig. 7, an arrangement of the textile structures as heat exchangers is
represented. The region of the textile structure is given for example by
the structure illustrated in Fig. 2b). One of the heat-exchanging media
flows firstly through the inflow region of the heat exchanger (lo), then
through the structure-free secondary channel region (11) towards the
textile structure (12). This is permeated by the medium at lower speeds
than in the inflow region since the surface to be permeated is greatly
increased by folding the structures. The medium subsequently flows
through the outflowing structure-free channels (13) into the oufflow
region (14).
In Fig. 8, various embodiments of the structured surfaces are
represented. An equally distributed, low speed through the structure
can be made possible for example by these different configurations
(tapering (Fig. 8a), hyperbolically tapering (Fig. 8b), sinusoidally
tapering) (Fig. 8c). An equally distributed speed through the structure
is advantageous in order to use all regions of the structure optimally for
the heat exchange. According to the arrangement, less compressed and
more compressed regions in the structure can vary along the fabric
structure (Fig. 7, (12)) and further promote uniform distribution.
In Fig. 8d, an embodiment with a plurality of folded structures
connected in succession is illustrated. As a result, a further increase in
the heat exchanger surface can be produced on a small constructional
space and hence an increase in power density in the case of a small
increase in pressure loss.

Patent claims
1. Heat transfer device comprising at least one channel for a heatabsorbing
medium and at least one channel for a heat-emitting
medium, at least one of the channels having a textile structure, at
least in regions, and the textile structure having regions
compressed at regular spacings, the compressed regions of the
textile structure being disposed in the transition region between
at least one channel for a heat-absorbing medium and at least
one channel for a heat-emitting medium for the production of a
thermal contact and the non-compressed regions of the textile
structure being disposed in the flow region of at least one
channel.
2. Heat transfer device according to claim 1,
characterised in that the channels for the heat-absorbing media
are separated from the channels for the heat-emitting media by a
separating wall, in particular a metal sheet, a foil, a membrane or
an outer surface of a tube or hose.
3. Heat transfer device according to the preceding claim,
characterised in that the compressed regions in the transition
region of the channels are connected integrally to the separating
wall, at least in regions, in particular by gluing, soldering,
welding, sintering or casting.
4. Heat transfer device according to one of the preceding claims,
characterised in that the textile structure at the compressed
regions has a coating which is impermeable or partially permeable
for the media.
5. Heat transfer device according to one of the preceding claims,
characterised in that, for separation of adjacent channels, in at
least one channel, an expandable hose or tube which is
impermeable for the media is integrated and/or, around at least
one channel, a shrinkable hose or tube which is impermeable for
the media is disposed, which enable contacting to the textile
structure by widening and/or shrinking.
6. Heat transfer device according to one of the preceding claims,
characterised in that the textile structure is permeated, at least in
regions, by a fluid for heat exchange.
7. Heat transfer device according to one of the preceding claims,
characterised in that the textile structure is embedded, at least in
regions, in a latently heat-storing, sorptive or catalytic stationary
medium or is coated therewith on the surface.
8. Heat transfer device according to one of the preceding claims,
characterised in that the textile structures of flow channels
adjacent to each other have different wire lengths and/or
spacings of the wires in the flow direction.
9. Heat transfer device according to one of the preceding claims,
characterised in that the spacings of the compressed regions are
varied such that the flow resistance in the flow channel is
adjustable via the wire lengths, wire diameters and/or spacings of
the wires.
10. Heat transfer device according to one of the preceding claims,
characterised in that the textile structure is configured to be
planar and has a fold and preferably comprises channels for at
least one medium in the plane of the surface, the surface of the
textile structure to be permeated by at least one medium being
increased relative to the inflow surface, as a result of which the
flow rate through the textile structure of the at least one medium
is reduced.
1 1. Heat transfer device according to one of the preceding claims,
characterised in that the wires, technical fibres or yarns hereof
have a diameter of 10 ym to 2 mm, preferably of 80 pm to 300
L'm.
12. Heat transfer device according to one of the preceding claims,
characterised in that the wires, technical fibres or yarns hereof
have, in flow direction, a spacing of 20 ym to 20 mm, preferably of
40 ym to 10 mm, and particularly preferably of 100 ym to 4 mm.
13. Heat transfer device according to one of the preceding claims,
characterised in that the wires, technical fibres or yarns hereof
are selected from the group consisting of
o metallic materials and the alloys thereof, in particular
copper, aluminium or stainless steel,
o carbon-containing materials, in particular carbon fibres,
activated carbon fibres,
0 glass- or ceramic fibres,
o polymer materials, in particular polypropylene (PP),
polyethylene (PE), polyamide (PA), polyether ketones (PEK),
polyester (PET) and
o composite materials hereof.
14. Heat transfer device according to one of the preceding claims,
characterised in that the textile structure has an intrinsic rigidity
which enables a self-supporting construction of the heat
exchanger.
15. Heat transfer device according to one of the preceding claims,
characterised in that the textile structure is a woven, knitted or
warp-knitted structur~o r a combination hereof.
16. Heat transfer device according to one of the preceding claims,
characterised in that the fabric structure used was coated
galvanically and, by melting the solder, the intrinsic stability of
the structure and the integral connection at the node points of
the wires is implemented to each other and to the separating foil.
17. Heat transfer device according to one of the preceding claims,
characterised in that, in the heat transfer device, lighting
elements, in particular optical fibres or elements having LEDs are
integrated, preferably in the form of incorporated wires, fibres or
yarns.
18. Heat transfer device according to one of the preceding claims,
characterised in that, in the heat transfer device, at least one
heating wire, in particular made of copper, copper-nickel alloys,
nickel-chromium alloys, constantan, manganin, nickel-iron
alloys, kanthal, is integrated.
19. Heat exchanger comprising a heat transfer device according to
one of the preceding claims.
20. Heat exchanger according to claim 19,
characterised in that the heat exchanger is a plate heat
exchanger, a tubular heat exchanger, a tubular lamellar heat
exchanger, a fiat t ~ ~ lbame e llar heat exchanger or a coaxial heat
exchanger.
21. Use of the heat transfer device according to one of the claims 1 to
18 in heat transfer to air or other gaseous media, in particular in
recirculation coolers, exhaust gas heat exchangers, convectors,
ventilation devices or oil coolers, in heat transfer to water or other
liquid media, in applications with phase change (evaporation,
condensation, solid/liquid) and chemical reactions and also in
combination with sorption materials or catalytic coatings.