Note: Descriptions are shown in the official language in which they were submitted.
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HEAT EXCHANGER
SUBJECT OF THE INVENTION
The present invention relates to a heat exchanger consisting of a
thermopositive core part
and thermopositive heat transfer elements, in which heat exchanger
- the heat transfer elements are thin and elongated objects, such as wires,
bristles,
fibers, strips or equivalent,
- the core part comprises at least two compression surfaces or pieces with a
compression gap between them where the heat transfer elements are squeezed so
as
~o to allow conduction of heat from the compression surfaces or pieces to the
heat
transfer elements or vice versa,
- the heat transfer elements are so mounted in the compression gap that at
least part of
the length of the thin wires, bristles, fibers, strips or equivalent of the
heat transfer
elements remains outside the compression gap.
PRIOR ART
In thermal engineering, many types of heat exchanger are known, which can be
used e.g.
for the heating or cooling of liquids, gases, powders or solid objects and
also for the
vaporization of liquids and condensation of vapors. An example of the cooling
of solid
objects is the cooling of electronic components.
The heat transfer elements of a heat exchanger are generally metallic parts
which are so
shaped that they allow a maximal capacity and efficiency of heat transfer from
a heating
medium to a medium to be heated or from a medium to be cooled to a cooling
medium.
The heat transfer surfaces of the heat transfer elements are usually shaped as
e.g. a
planar, grooved or spicular surfaces. The commonest solutions consist of
laminated
radiators, finned tubular radiators, or finned tubular radiators having fins
cleaved into a
spicular form. Generally, however, fairly simple forms are adopted because of
the cost, but
in this case it is difficult to obtain a large heat delivery surface
especially in the gas
3o carrying section as it also involves a large pressure drop. Thus it has
been found that
designing the shape of e.g. heat transfer fins or equivalent is not a very
simple task if the
aim is to produce a really efficient heat exchanger, vaporizer or condenser in
which the
pressure drop especially in the gas or steam carrying section is sufficiently
small.
OBJECT OF THE INVENTION
The object of the invention is to achieve a new heat exchanger that does not
have the
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disadvantages described above and is substantially more efficient than prior-
art heat
exchangers.
FEATURES CHARACTERISTIC OF THE INVENTION
The heat exchanger of the invention is characterized in that
- the core part of the heat exchanger comprises at least one helical elongated
body,
such as a spiral tube or a rod bent like a helical spring, or two or more
bodies, such as
tubes or rods, twisted about each other,
- and that the heat transfer elements of the heat exchanger, such as wires,
bristles,
~o fibers, strips or equivalent, are squeezed between the helices of the
helical body or
between the bodies twisted about each other.
By using a plurality of thin wires, bristles, fibers or strips arranged in
contact with the
compression surfaces or pieces of the core part of the heat exchanger, a large
heat
delivery surface and a good heat transfer efficiency are achieved. Still, a
sufficient space
for a gas or steam flow is left between the wires so that the pressure drop of
the flow
remains small.
EMBODIMENTS OF THE DEVICE OF THE INVENTION
2o A preferred embodiment of the device of the invention is characterized in
that
- the core part of the heat exchanger comprises
- one helical tube or one rod bent like a helical spring, or
- one tube or rod bent over, in which the two tube or rod portions placed
against
each other have been twisted about each other, or
- two or more tubes or rods placed against each other and twisted about each
other,
- and that opposite ends of the heat transfer elements, such as wires,
bristles, fibers,
strips or equivalent, extend in opposite directions from the compression gap
between
the helices of the core part bodies or between the bodies or parts thereof
twisted
about each other, on both sides of the compression gap.
The heat transfer elements of the heat exchanger, such as wires, bristles,
fibers, strips or
equivalent, are directed radially in different directions from the compression
surfaces or
pieces of the core part. By using radial wires, bristles, fibers or strips, a
uniform heat flow
in different directions from the core part is achieved.
A second preferred embodiment of the device of the invention is characterized
in that
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- the heat transfer elements of the heat exchanger, such as wires, bristles,
fibers, strips
or equivalent, are squeezed by their midpoint in the compression gap between
the
core part portions twisted about each other or between parts thereof,
- and that the ends of the heat transfer elements diverging radially in
different directions
from the compression gap of the core part are of equal length so that the heat
exchanger has a mainly circular cross-sectional form.
A third preferred embodiment of the device of the invention is characterized
in that
- the core part of the heat exchanger comprises a bent-over elongated body,
such as
1o tube or rod, in which the two parts bent against each other have been
twisted about
each other,
- and that the heat transfer elements, such as wires, bristles, fibers, strips
or
equivalent, are squeezed in the compression gap between the two parts of the
elongated body twisted about each other.
A fourth preferred embodiment of the device of the invention is characterized
in that
- the core part of the heat exchanger comprises a bent-over tube whose two
parts
placed against each other have been twisted about each other,
- that the heat transfer elements, such as wires, bristles, fibers, strips or
equivalent, are
2o squeezed in the compression gap between the two parts of the bent-over tube
twisted
about each other,
and that an outlet for a heat transfer medium, such as a liquid, vaporized
liquid,
condensable vapor or a flowing gas, is located at the same end of the heat
exchanger
as the supply opening for the medium.
A fifth preferred embodiment of the device of the invention is characterized
in that two or
more heat exchangers formed from helical tube are connected in parallel in the
same
space so that the inlet orifices of the heat exchangers for the supply of a
heat transfer
medium are connected together and similarly the medium outlet orifices of the
heat
3o exchangers are connected together.
A sixth preferred embodiment of the device of the invention is characterized
in that one or
more heat exchangers formed from helical tube are implemented as a separate
unit having
a preferably circular cross-section and so designed that it can be easily
mounted in and
removed from its place of installation, which preferably is a ventilation duct
of circular
cross-section.
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A seventh preferred embodiment of the device of the invention is characterized
in that the
heat transfer wires placed in the compression gap between the tubes or tube
portions of
the heat exchanger twisted about each other are at least partially immersed in
a liquid to
be vaporized.
An eighth embodiment of the device of the invention is characterized in that
the heat
transfer wires placed in the compression gap between the tubes or tube
portions of the
heat exchanger twisted about each other are at least partially located in a
vapor space
where condensation of vapor occurs on the surface of the heat transfer wires.
According to a yet another preferred embodiment of the invention, the heat
transfer wires
squeezed between the tubes or tube portions twisted about each other are
copper wires,
aluminum wires or carbon fibers. Copper wires may also be shaped e.g. by
flattening their
ends into a flat shape.
EXAMPLES OF EMBODIMENTS
In the following, the invention will be described by the aid of examples,
referring to the
attached drawings, wherein
2o LIST OF FIGURES
Fig. 1 presents a side view of a heat exchanger according to the invention.
Fig. 2 presents a section of Fig. 1, taken along line I I-II.
Fig. 3 presents a side view of a partially sectioned heat exchanger according
to the
invention, mounted in a ventilation duct or steam conduit.
Fig. 4 presents a section of Fig. 3, taken along line IV-IV.
Fig. 5 presents a partially sectioned side view of the heat exchanger in Fig.
3,
placed in powder.
Fig. 6 presents a partially sectioned side view of two heat exchangers as
presented
in Fig. 1, connected together and placed in a transverse duct.
3o Fig. 7 corresponds to Fig. 3 and presents a heat exchanger according to the
invention, mounted in an air duct or vapor conduit.
Fig. 8 presents a diagrammatic cross-section of a unit consisting of seven
heat
exchangers.
Fig. 9 presents a perspective view of a heat exchanger unit placed in an air
duct.
Fig. 10 presents a section of Fig. 9, taken along line X-X.
Fig. 11 presents a side view of a ventilation duct and a heat exchanger unit
as shown
in Fig. 9 designed to be mounted in it.
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Fig. 12 corresponds to Fig. 11 and presents the heat exchanger unit installed
in the
ventilation duct.
Fig. 13 presents a heat exchanger according to an embodiment of the invention
in
side view.
5 Fig. 14 presents a sectioned side view of a vaporizer according to the
invention.
Fig. 15 presents a heat exchanger according to the invention in side view.
Fig. 16 presents a section of Fig. 15, taken along line XIV-XIV.
Fig. 17 corresponds to Fig. 16 and presents a second embodiment.
Fig. 18 presents a partially sectioned side view of a heat exchanger according
to an
~o embodiment of the invention.
Fig. 19 presents a section of Fig. 18, taken along line XXVII-XXVII.
Fig. 20 presents a partially sectioned side view of a heat exchanger according
to an
embodiment of the invention.
Fig. 21 corresponds to Fig. 2 and presents a cross-section of a heat exchanger
~s according to yet another embodiment.
DESCRIPTION OF THE FIGURES
Fig. 1 presents a heat exchanger 30 having a core part 31 consisting of a
metal tube which
has been first bent over, whereupon the two tube portions bent against each
other have
2o been twisted about each other. When the tube portions are being twisted
about each
other, the heat transfer wires 32 are left squeezed between the portions of
the helical tube
31 being tightened against each other. In Fig. 1, to clarify the structure of
the heat
exchanger, only a relatively small number of heat transfer wires 32 are shown
between the
two parts of the tube 31 twisted about each other, but in practice the heat
exchanger may
25 have a very dense array of a large number of wires. Connected to the ends
of the helical
tube 31 of the heat exchanger 30 is a connection piece 35 comprising an inlet
orifice 33
and an outlet orifice 34 for a heat transfer medium, such as a liquid.
In all the embodiments described below, the medium used on the side of the
heat transfer
3o wires may be a liquid, a vaporizable liquid, a condensable vapor or a
flowing gas, usually
air. In embodiments comprising a helical tube, the medium flowing inside the
tube may be
a gas, a condensable vapor, a vaporizable liquid or a heat carrier liquid,
usually water.
Fig. 2 presents a cross-section of a heat exchanger 30, showing that the heat
transfer
s5 wires 32 are squeezed between the two parts of a helical tube 31. The wires
32 are
directed radially away from the gap between the helical tubes 31.
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In Fig. 3, a heat exchanger 30 is mounted in an air duct 36 where an air
current is flowing.
Via the heat transfer wires 32 and a liquid supplied into the helical tube 31,
heat can be
transferred from the liquid to the air flowing in the duct 36 or vice versa.
The medium
supplied into the helical tube 31 may also be a vaporizable liquid, e.g. a
vaporizable
refrigerant in a refrigerator application. A heat exchanger 30 as illustrated
in Fig. 3 may
also be mounted in a steam conduit, where steam will condense on the surface
of the
wires 32.
Fig. 4 presents a cross-section of the heat exchanger 30 in Fig. 3. It can be
seen from the
figure that the heat transfer wires 32 mainly fill the duct 36 completely. The
wires 32 are so
thin that their air drag in the duct 36 is insignificant. Still, the total
area of the wires 32 is so
large that they produce efficient heat transfer.
Fig. 5 illustrates another way of using a heat exchanger 30. In this case, the
heat
~s exchanger 30 is placed e.g. in metal hydride powder 37. Heat transfer wires
32 and helical
tubes 13 perform effectively also when heat is to be transferred into or from
powder.
Fig. 6 presents two heat exchangers 30a and 30b connected together so that the
heat
carrier liquid is supplied into both heat exchangers 30a and 30b via a common
inlet
2o channel 33. Correspondingly, the heat exchangers 30a and 30b also have a
common
outlet channel 34. By combining a number of heat exchangers 30 in this way, it
is possible
to achieve a sufficiently efficient unit which can be used e.g. as a cooler in
a motor vehicle.
In this Fig. 6, as in the figures illustrating the other examples of the
embodiments of the
invention, a relatively small number of heat transfer wires 32 are shown to
visualize the
25 structure more clearly. In actual heat exchangers, however, it is
preferable to have a large
number of heat transfer wires 32. As the wires 32 have a low air drag, they
can fill the air
flow duct 36 around the heat exchangers 30a and 30b completely.
Fig. 7 presents a heat exchanger 30 placed in a duct 36 and comprising two
separate
3o tubes 31 a and 31 b twisted about each other. The adjacent ends of both
helical tubes 31 a
and 31 b at each end of the heat exchanger 30 are connected both to an inlet
channel 33
and to an outlet channel 34. Thus, the heat carrier liquid flows in the same
direction in both
helical tubes 31 a and 31 b. As the air in the duct 36 flows in the opposite
direction relative
to the liquid flow, the result is a heat exchanger 30 functioning in a new way
on the
35 counter-current principle known in itself. The medium fed into the helical
tube 31 may also
be a vaporizable liquid, e.g. a vaporizable refrigerant in a cooling
application. The duct 36
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may also carry a steam flow, in which case the heat exchanger functions as a
condenser
as steam condenses on the wires 32.
Fig. 8 presents a diagrammatic cross-section of a heat exchanger unit 40
comprising
seven heat exchangers 30 according to the invention mounted in a duct 36. As
shown in
the figure, the heat transfer wires 32 of each heat exchanger 30 partially
intermesh with
corresponding heat transfer wires 32 of adjacent heat exchangers 30. In this
way, the duct
36 is so densely filled with heat transfer wires 32 that a good efficiency of
the heat
exchanger unit 40 is achieved.
io
Fig. 9 presents a heat exchanger unit 40 designed to be placed in a service
door of a
ventilation duct and comprising seven heat exchangers 30 grouped in the manner
illustrated by Fig. 8. For the sake of clarity, Fig. 9 only shows some of the
heat exchangers
30. For those heat exchangers that are not shown in Fig. 9, only the ends of
the liquid
supply pipes are depicted, to which the ends of the heat exchangers are
connected.
The heat exchanger unit 40 of Fig. 9 is provided with a support plate 41 of
semicircular
cross-section and flanges 42a and 42b comprised in it. Placed at each end of
the heat
exchanger unit 40 is a ring 43, 44. Ring 43 is an inlet ring supplying a heat
transfer
2o medium into all heat exchangers 30 in the heat exchanger unit 40.
Correspondingly, ring
44 at the opposite end of the heat exchanger unit 40 is an outlet ring common
to all the
heat exchangers 30.
As shown in the cross-sectional diagram in Fig. 10, the heat transfer medium
is passed via
25 the ring f to all the heat exchangers 30 in the heat exchanger unit 40.
The following figures 11 and 12 show how the flanges 42a and 42b of the heat
exchanger
unit 40 can be fitted to corresponding flanges of a ventilation duct, with the
support plate
41 forming part of the ventilation duct.
Fig. 11 presents a ventilation duct 50 and a heat exchanger unit 40 designed
to be fitted in
it. The ventilation duct 50 is provided with a service door opening 51 located
in its lower
surface and having a size corresponding to the support plate 41. The heat
exchanger unit
is mounted by placing its mounting flanges 42 against mounting flanges 52
provided at
35 the edges of the service door opening 51.
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Fig. 12 presents the heat exchanger unit 40 installed in the service door
opening of the
ventilation duct 50. The heat exchangers 30 now fill the entire cross-
sectional area of the
ventilation duct 50. Fig. 12 shows in a diagrammatic form the topmost and
bottommost
heat exchangers in the duct 50 to visualize the placement of the heat
exchangers in the
s ventilation duct 50. After the heat exchanger unit 40 has been mounted in
position, the
mounting flanges 42 of the support plate 41 of the heat exchanger unit 40
fastened to the
mounting flanges 52 of the service door opening and the pipes for a heat
transfer medium
connected to both the inlet 33 and the outlet 34, the heat exchanger unit 40
will be ready
for use.
Fig. 13 presents an embodiment of the heat exchanger 30 in which the heat
transfer wires
32 are squeezed between the spirals of a single helical tube 31.
Fig. 14 presents a vaporizer 60 comprising a heat exchanger 30 placed in a
chamber 61
and immersed in vaporizable liquid 62 in the chamber 61. Part of the heat
transfer wires 32
of the heat exchanger 30 is inside the vaporizable liquid 62 and part of them
is above the
liquid surface, in the air space of the chamber 61.
Fig. 15 presents a heat exchanger 30 comprising several elements 31 twisted
about each
other. The elements 31 may be rods, such as e.g. four rods, or two rods bent
over against
each other as shown in Fig. 16. In this case, heat transfer occurs by
conduction via the
rods 31.
The elements 31 in Fig. 16 may also consist of tubes, as shown in the cross-
sectional view
in Fig. 17, in which case heat transfer occurs by the agency of a medium, such
as a liquid,
flowing through the tubes 31.
Fig. 18 and 19 present a heat exchanger 30 designed for the cooling of
electronic
components. In this case, the core part 31 of the heat exchanger 30 and the
cooling plate
47 attached to it can be mounted on top of a heat developing component 48,
such as e.g.
a microprocessor.
Fig. 20 likewise presents an embodiment of the heat exchanger 30 in which the
cooling
plate 47 has been pressed e.g. onto an electronic component 48 to be cooled.
In this
embodiment, the helical tubes 31 of the heat exchanger 30 are mounted in an
upright
position.
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Fig. 21 presents a cross-sectional view of an embodiment of the heat exchanger
30
consisting of a combination of nested heat exchangers. Placed inside the
helical tubes 31 a
and 31 b of the main heat exchanger 30 are corresponding heat exchangers 30a
and 30b
having core parts 31 a and 31 b of thin metal wire. Using such an arrangement,
the internal
heat transfer in the helical tubes 31a and 31 b of the main heat exchanger 30
can be made
more effective.
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