Note: Descriptions are shown in the official language in which they were submitted.
~1289Z8
The present invention relates to a device for trans-
ferring heat through tubes and to tubes suitable for this
purpose, more especially the invention is concerned with such
tube~ which are thin-walled and composed of a melt-spinnable
synthetic polymer.
t Heat-exchangers made of tubes, and also hollow
threads or hollow fibres, are known, in which the tube~ are
arranged in straight lines, parallel with each other, and
spaced from each other.
Thin-walled tubes and their method of production
have previously been proposed, such tubes being comp~sed of
a melt-spinnable synthetic polymer, and having a cross-
section of flow of from 30 to 95% of the total cross-section
and a breaking elongation of less than 100%.
A "thin-walled tube" in the context of the invention
i8 a hollow, cylindrical configuration of any length having,
for example, a circular or elliptical cross-section, whose
wall thickness which is constant in the longitudinal and
circumferential direction iQ less than about 15% of the
largest external dimen~ion of the tube cross-section. With
a circular cross-section, the largest external dimension
corre~ponds to the external diameter and with an elliptical
cro~s-section it corresponds to the largest external axis.
The thin-walled tubes of the invention are stronger
than conventional thin-walled tubes but neverthele~s, have a
large cross-section of flow and a closed, i.e., undamaged
sheath. They are characterised by an internal flow cross-
section ranging from 30 to 95% of the total cross-section and
by an elongation at rupture of less than 100~/o~ Tubes having
a cross-section of flow of from 60 to 95% of the total cross-
section are preferred.
1128928
Thin-walled tubes can be produced from any conventional
melt-spinnable polymers. Examples of particularly suitable
polymers, due to their ~pecial properties in use, include the
polyamide~, in particular polycaprolactam and polyhexa-
methylene adipic acid amide, polyester~, in particular poly-
ethyleneterephthalate; polyolefins, in particular polyethylene
and polypropylene: and polyvinylchloride.
Polyesters, in particular polyethyleneterephthalate
are particularly preferred due to their chemical stability
for example, toward food stuffs, liquids containing carbon
dioxide or the like. Tubeq compo~ed of polyolefins, in
particular polypropylene are preferred if chemical stability
i8 desired as well as good thermal stability.
The tubes are produced from polyamides, in parti-
cular from polyhexamethylene adipic acid amide if high
~trengths are desired.
Stabilisers, carbon black, pore forming agents or
other additives can be added to the polymers.
The tubes usually have a sheath which does not
allow any liquids through. When using thin-walled tubes for
filter units, however, it is advantageous for the thin-walled
tube8 to have a microporous ~heath.
Thin-walled tubes of thi~ type are produced in the
manner described above by the melt-spinning of synthetic
polymers, the production process being characterised in that
the take-off speed is higher than 3500 m~min. Take-off speeds
ranging from 5000 to 7000 m/min are preferred. In fact,
at these take-off speeds, the thin-walled tubes have a
Atrength which could otherwise only be achieved by additional
(but difficult) re-drawing.
ilZ89Z8
In order to avoid large spinning height~ (distance
from spinneret to take-off device) it is propo~ed that the
phenomenon of the `'natural bending of the thread" be utilised,
This generally occur~ during the melt-spinning of threads
from synthetic polymers in a fairly large distance from the
spinneret if the take-off device is moved laterally from
its normal position located substantially vertically below
the spinneret. It can be seen clearly if, for example, a
monofilament polyester thread having a final count of 100
dtex is taken off at 3700 m/min and the take-off device
initially arranged vertically below the spinneret (rapid
spooling device or thread injector) i9 gradually removed
in a horizontal direction and optionally lifted simultaneously
in a vertical direction,
In spite of the changed position of the take-off
device the thread continues to move vertically downward~
below the spinneret over a certain distance and is then
deflected toward the take-off device, The region of this
"natural" bending of the thread, i.e., bending of the thread
which is adjusted without additional mechanical thread-
guiding devices, extends only over a Iength of a few centi-
metres and does not change its position substantially even if
the po~ition of the take-off device is changed significantly.
On the other hand, the position of the region of the "natural"
bending of the thread can be varied by changing the spinning
conditions. For example, it becomes more distant when the
through-put of-melt from,the spinneret is increased. The
phenomenon occurs even during the rapid spinning of thin-
walled tubes.
Using this phenomenon, it is possible to keep the
spinning height low by the lateral arrangement of the take-
off device, while at the same time, maintaining the cooling
~:lZ89Z8
distance needed for cooling the freshly spun thread~,
Moreover, if, as already proposed, the distance of
the take-off device from the region of the "natural bending
of the thread" is selected sufficiently large, the tube is
subjected to re-drawing, in which process it is stretched
to from two to three times its original length.
Although it is not po~sible to deflect the rapidly
spun thin-walled tubes in the region of the "natural bending
of the thread" mechanically, i.e., using a deflecting
device, deflection is po~sible by arranging a baffle plate
vertically below the spinneret, so as to shift the region
of the "natural bending of the thread" closer to the
spinneret. The region of the "natural bending of the thread"
can also be shifted to a coolant by arranging, for example,
a small water tank instead of the above-mentioned baffle plate.
In order to produce stable tube configurations
having larger external dimensions and very small wall thick- !
nesses, a cavity-forming fluid, in particular a gas, is blown
into the tube whilst the thin-walled tube is being spun from
the spinneret,
Thin-walled tubes of this type which are spun by
rapid spinning, are suitable, for example, for the production
of heat exchangers in which case they generally have a
circular cross-section and an external diameter of from about
40 to lOOO~m or more with wall-thicknesses of about 5 to 50 ~m
or more.
It is the purpose of the present invention to
improve known heat-exchangers consisting of hollow fibres as
regards their heat-transfer capacity and serviceability, and
to make available a device for the transfer of heat which can
be produced easily and rapidly and does not have the dis-
~289Z8
advantage~ of known hollow-fibre heat-exchanger~.
According to the invention, this purpose is achieved,
on the one hand, by utilizing the flexibility of thin-walled
tubes by designing the device accordingly and, on the other
hand, by special configurations of the thin-walled tubes
already proposed which increase their thermal conductivity
and heat-transmission and, finally by imparting suitable
shapes to the tube~.
According to the invention there is provided an
apparatus for transferring heat through tubes comprising a
plurality of thin-walled tube~ composed of a melt-spinnable
synthetic polymer, each tube having a flow cross-section or
internal cross-section of between 30 and 95% of the total
cross-section and an elongation at rupture of less than 100~.
In one preferred embodiment of the invention,
each individual thin-walled tube is arranged over most of~ts
length, preferably over its entire length, and/or most of the
thin-walled tubes, preferably all of them, are arranged in
the form of regular and/or irregular tubes.
A heat-transfer device of thi~ kind, made out of
thin-walled tubes, has greater resistance to external
mechanical stre~sing, thus assuring undiminished heat-
transfer capacity, evèn after long periods in operation.
This embodiment of the device according to the
invention therefore does not have the disadvantages of the
known heat exchangers composed of hollow threads in which the
hollow threads are arranged in straight lines, parallel to
each other and at distances from each other. In fact, this
known arrangement, of the type which is also conventional in
metal tubùlar heat exchangers, makes the production of such
heat exchanger~ from hollow threads difficult and expensive.
~lZ89~8
In addition, with this known arrangement of the hollow threads,
the bundles of hollow threads can be damaged, for example,
buckled, even by minor external mechanical influences.
The looped or partially looped arrangement of the
thin-walled tubes in an apparatus according to the
invention which is also called a heat exchanger in the rest
of the description for the sake of simplicity, is achieved
according to the invention in a simple manner. In parti-
cular it is achieved in that one or more continuous thin-
walled tubes are wound using a spooling or winding device
with one or more thread guides which are moved to and fro
parallel to the rotational axis of the spooling device, for
example, on a perforated tubular reel holder (also known as
a bobbin or spool) and, in this way, form a single or
multiple layered spool or wound member.
This arrangement is particularly advantageous
since, in the serviceable condition of the apparatus, the
thin-walled tubes have the shape of a spatially extending 1
coil, the thin-walled tubes advantageously being arranged in
several layers for achieving an easily penetratable winding
packet which i A ~table in shape in such a way that the thin-
walled tubes in each layer contact the thin-walled tubes of
the adjacent layers and cross, optionally several times.
This arrangement of the thin-walled tubes allows a large
heat tran~fer surface in a small space since, although the
thin-walled tubes touch each other at the points of inter-
section, only an insignificant proportion of the heat transfer
surface is lost by the reciprocal contact between the thin-
walled tubes.
-- 6 --
llZ8928
The spool holder accommodating the spooled or wound
member need not necessarily have a circular cross-section as
its cross~section can also be designed elliptical or as a
polygon, in particular as a rectangle with rounded corners.
Similarly, the reel holder used for producing the spooled or
wound mem~er can also have a cross-section which increases
or decreases along its longitudinal axis. Thusj its sur~ace
area can be designed, for example, conical, diabolo shaped,
truncated pyramid shaped with rou~ded lateral edges or barrel-
shaped, so that the thin-walled tubes wound on a reel holder
shaped in this way generally form a spooled or wound member
whose shape corresponds to the shape of the respective reel
holder.
In another embodiment of the apparatus according to
the invention, the thin-walled tubes have the shape of a
spiral lying in one plane.
The heat exchanger according to the invention can,
however, also be produced from one or more sheets which have
been produced by a weaving, knitting or stretching method
or a depositing method. Like the spooled or wound member,
sheets'of this type can also be produced in a rapid and
simple manner,
In order to pr~oduce a heat exchanger, according to
the invention from a spooled or wound member, two face ends
can be cast on a short portion, measured in the longitudinal
direction, of the wound member, in for example, a curable
casting composition such as, for example, cast resin or poly-
urethane, the casting composition penetrating completely
into this region of the wound member and optionally forming
one flange-like projection outside each wound member having
a larger circumference than the wound member. A flange-like
~289Z8
projection of this type can, however, also be provided on
one only of the two faces of the wound member. The arc-
ahaped turn backed parts of the individual layers of the
wound member lying at the ends of the wound member are
removed by taking off a proportion of each of these (flange-
~-~ shaped) pxojections from the end, into the region of the
thin-walled tubes, and a configuration is produced in this
way from the original wound member which consists of a
plurality of tubular pieces arranged in several layers in the
form of a coil and cro~ing each other severaI times, who~e
openings emerge from the casting composition at the external
face, generally running perpendicularly to the longitudinal
axis of the wound member, of the remaining part of each of
the (flange-like) projection~ described above.
To produce a heat exchanger according to the
invention from sheets, one or more edges of the sheets which
are optionally also superimposed, can be cast in a suitable
, ~
manner, for example, in cast resin, in each case and the
; openings of the thin tubes can then be freed in a similar
manner, aa already described above for spooled and wound
members.
,
By winding or shifting the thin tubes in a suitable
,~ , . . .
manner or by arranging them in another manner and by cutting
the bundle of tubes in a suitable manner it is possible to
. .
~; produce a heat exchanger according to the invention in which
the inlet openings and the outlet openings of the thin tubes
lie in one and the same plane, but are shifted, for example,
by 180 and/or at equal or differing distances from each
other in each case and thus arranged in such a way that all
inlet openings lie in one half of this plane and all outlet
openings lie in the other half of this plane.
- 8 -
~lZ89Z8
It is also po~sible to produce a heat exchanger
according to the invention which allows as much fluid as
desired to participate in the heat transfer, without the
individual fluids being mixed to~ether.
A heat exchanger according to the invention pro-
duced from a spooled or wound member can, for example, be
equipped in such a way that the inlet openings and the
outlet openings for a first fluid lie at one end of the
heat exchanger and those for the second fluid lie at the
other end of the heat exchanger.
To produce a plurality of smaller heat exchangers,
it is possible according to the invention to divide the
spooled or wound members or sheets intended for the production
of the heat exchanger into units! for example, strips or
discs or the like of desired size, in which case the thin
tubes are preferabl;y fixed in shape and position beforehand
in a suitable manner, for example, by casting into cast
resin or the like as already described, in those regions in
which the division is to take place, and their openings can
thus be freed without difficulty by the division.
It is also posslble within the scope of the
present invention to cast the thin tubes in a material which
is a good conductor of heat in order to transfer heat in this
manner from one fluid to the said material which is a good
conductor of heat or vice versa. A heat exchanger according
to the invention which is designed in this way and which also
has, for example, two separate circuits for two fluids which
are to be kept apart allows heat to be transferred from, for
example, the first 1uid initially into the cast member which
is a good conductor of heat and thence to deliver it to the
second fluid. It is also possible with a heat exchanger of
_ g _
~lZ89Z8
this type, for example, to deliver the heat taken up, for
example, by radiation, from the cast member which is a good
conductor of heat, simultaneously to two fluids.
The heat exchanger according to the invention iq
suitable for solving even the most demanding problems of
heat transfer of the type which can arise, for example, during
evaporation or condensation. In particular, the heat
exchanger according to the invention is suitable wherever
there are only relatively small temperature differences for t
the recovery of energy which inevitably demand large heat
transfer surfaces which obviously have to be arranged in the
minimum of space. Due to the desirable corrosion properties
of the thin tubes which can be used for the production of the
heat exchanger according to the invention, the heat exchanger
according to the invention is particularly ~uitable for
corrosive media such as, for example, acids and caustic
solutions. By selecting suitably thin tubes to be used,
it is possible, by means of the known differing surface
properties thereof, also to use the heat exchanger according
to the invention for those fluids which tend to form deposits
on the tube walls in conventional metal tubular heat
exchanger 8 .
The heat exchanger according to the invention is
therefore equally suitable for chemical processes, in the
production or conversion of energy, in refrigeration, in air-
conditioning, in the food industry, in central heating, in
land, in water and air vehicles, in particular as an oil
cooler, as a water cooler for discharging enginè heat or for
heating the fresh air supplied to the interior of the
vehicle, as a condenser and as an evaporator, in particular
also as a flash evaporator. The heat exchanger according to
-- 10 --
11289Z8
the invention is quite specifically suitable for heat pump
devices in which, for example, heat from the surrounding air
or from the ground is used for heating housing space or as
collectors for receiving the heat of the ~un, for which
purpose those embodiments of the heat exchanger according
to the invention in which the thin tubes are arranged in only
one layer and, moreover, are black, have proven particularly
advantageous.
The heat exchanger according to the invention is
thus suitable for ~olving most problems of heat transfer,
i,e., for the heat transfer of gaseous fluids to gaseous
fluids, from liquid fluids to liquid fluids, from liquid
fluids to gaseous fluids and vice versa, from solid mate-
rials to gaseous and/or liquid fluidY and vice versa, in
which case, care has to be taken to limit the temperature
of the materials participating in the heat exchange are
limited by the physical and chemical properties of the thin
tubes used.
When dimensioning the heat exchanger according to
,." !
the invention, it ~hould be noted that the heat transfer
- surface attainable per unit volume available is greater,
the smaller the diameter of the tubes to be used. The
amount of heat to be transferred generally increases as the
~ diameter of the tubes decreases if the cross-section of
t flow of all thin tubes and the quantity of fluid remain
constant. It should however be noted that the pressure loss
in the thin tubes also increases in this case. It should
also be noted that the buckling strength or nick-resistancè
of the thin-walled tubes generally decreases as the diameter
increases and the wall thickness stays constant. With a
suitable choice and dimensioning of the thin tubes used for
-- 11 --
- ~\
~lZ89Z8
the heat exchanger according to the invention, it is possible
to achieve specific heat transfer capacities which can be
better, and in part even considerably better than those
which can be achieved with conventional metal tubular heat
exchangers. The choice of suitable thin tubes should be
made as far as possible in such a way that the heat trans-
mission re~istance through the wall of the thin tubes is
substantially negligible relative to the heattransfer
resistances occurring inside and outside the thin tubes.
This means that thin tubes made of a material having
relatively good propertie~ of thermal conductivity should
~' have thicker walls than those with very low thermal con-
ductivity value~. ;
The term cross-section of the thin tubes, the
spooled or wound member or the reel holder is interpreted in
the context of the invention as the cross-sectional area
obtained if a thin tube, a spooled or wound body or a reeL
holder is cut at a random point or at a point described in
more detail perpendicularly to its longitudinal or
rotational axis. In the case of a round thin tube, a
circular cross-section is obtained in this way. In the case,
for example, of a spooled or wound member which is wound on
a reel holder having a rectangular cross-section with'
;' rounded corners, a rectangular annular cross-section with
rounded corners is obtained according to this definition.
The term loop form in the context of the present
invention is interpreted'as that form which differs from a
rectilinear form and, in particular, that type of flat or
three-dimension-al curvature in which the' radius of curvatùre
is sufficiently large to prevent buckling or nicking of the
thin tubes. The radius of curvature is generally smaller than
1~289Z8
1 m but it can also be larger. To achieve the object forming
a ba~is of the present invention, it is not nece~sary for
all thin tubes to have a loop form over their entire length,
but rather it is sufficient for a majority of the thin
tubes to have a loop form, i.e., for each individual thin
tube in the apparatus according to the invention to have a
loop form over the majority of its length and/or for recti-
linear and loop-form thin tubes to be present providing the
total length of all the thin tubes and/or tube portions
~7 10 present in loop form is greater than the total length of all
rectilinear thin tubes and/or tube portions.
This loop form of the thin tubes allows the thin
tubes to cro~ over optionally several times at ~ubstantially
~hort intervalq and to support each other in this way!so that
each thin tube ~8 generally unsupported only over relatively
short portions of their length 90 that the risk of;the thin
tube~ being buckled or nicked is reduced considerably.
In the ~earch for possible further improvements to
known heat-exchanger~, and to the device according to the
invention, it was found, ~urprisingly enough, that an
additional increase in héat-transfer capacity, and further
improvement to the ~erviceability of hollow-fibre heat-
exchangers, might be achieved by special configuration~ of
the thin-walled tubes already proposed, and by the use of a
few of the already proposed designs thereof in the device
according to the invention.
In another a~pect of the invention novel thin-
walled tubes are provided.
In this connection, outstanding result~ are obtained
when the tubea of the invention are employed in the apparatus
for transferring heat.
- 13 -
,~.
,.
.
.. .
, , .
~ ~128928
Thu~ in accordance with the invention there i9 provided
a thin-walled tube composed of a melt-spinnable synthetic
polymer, having an internal cross-section of between 30
; and 95% of the total cross-section and an elongation at
rupture of less than 10~/ol the tube being characterised by
at least one characteristic selected from: i) the coefficient
of heat-transm~ssion of the wall of the thin-walled tube i9
at least 1500 to at least 4500 W/m2K, ii) the outside diameter
- of the thin-walled tube is between 0.04 and 4 mm, iii) the
wall-thickness of the thin-walled tube is between 5 and 100 ~m,
iv) at least one of an internal and an external surface of
the thin-walled tube is profiled, v) the cros~-section of the
thin-walled tube varies, in the longitudinal direction, in
at least one of shape and size, vi) the thin-walled tube
consists of two or more component~, vii) only some of the
components of the thin-walled tube are porous.
In the case of iii), the wall-thickness~of the thin-
walled tube~ is preferably within the range of 5 to 20 ~m.
- In the case of v), the cross-section of the thin-
walled tubes may vary continuously or intermittently and
po~sibly periodically.
Since thin-walled tubes having the properties
mentioned above have not only proven satisfactory in a device
- for transferring heat having the characteristics of the
invention, but can also lead to improvements in conventional
hollow-fibre heat-exchangers, thin-walled tubes h~ving the
above-mentioned properties are included in the invention.
The thin-walled tubes of the invention may possess the
indicated properties individually or in any desired combination.
'~ 30 It was alco found that an increase in heat-transfer
capacity and improvements in serviceability, of the device
- 14 _
,,
~'
11289~8
according to the invention for transferring heat may also be
achieved by a suitable choice of quite specific embodiments
of the proposed thin walled tubes. In thi~ connection,
particularly good results are obtained if:
a) the thin-walled tubes contain fillers, stabilizers,
additives, pigments, or the like, and/or
b) the thin-walled tubes are substantially circular in cross-
section, and/or
c) the outside diameter of the tubes is between 0.04 and 1 mm,
- 10 and/or
d) the wall-thickness of the thin-walled tubes is between 5
and 50 ~m, and/or
e) the thin-walled tubes are porous.
Here again, according to the invention, thin-walled
tubes may be used which possess the properties already
pro~osed either singly or in combination.
For the purpose of increasing the heat-transfer
capacity of the device of the invention, it is particularly
advantageous to use thin-walled tubes containing good heat-
conducting substances, for example, metals, graphite, or
the like, in the form of dust or powder. However, the thin-
walled tubes may also contain fillers, stabilizers, additives,
carbon black, pigments, or the like.
The use of micro-porous thin-walled tubes, together
with high pressures, makes it possible not only to transfer
heat through the walls thereof, but also to cool a liquid,
in that some of the liquid to be cooled evaporates or vapourizes
on the surfaces of the porous thin-walled tubes.
The thinness of the walls of the tubes produces a
heat-exchanger having a greater heat-exchange capacity, and
this may be stiLl further increased in that, due to the high
- 15 _
1128928
strength of these tubes, the permissible op~rating pres~ure
within them, and the flow of fluid therethrough, are relatively
high.
Suitable thin-walled tu~e for the heat-exchanger
according to the invention are those of, for example, elliptical,
triangular, square, pentagonal, hexagonal or polygonal cross-
section, but more particularly those of circular cross-
section, since in the case of a heat-exchanger according to
- the invention made with intersecting thin-walled tubes of
circular cross-section, the said tubes make only point-
contact with each other, and only a small part of the total
heat-exchange surface is lo~t at these point contacts.
The thin-walled tubes may, moreover, be internally
and/or externally profiled. Two, three or more tubes, lying
parallel with each other, may also be connected together at
their contacting surfaces by fusing, welding, or adhesion,
or the like. Also ~uitable are thin-walled tubes of which
the cross-sections vary, in the longitudinal direction, in
shape and/or size continuously, intermittently and, optionally,
periodically. Thin-walled tubes of this kind may advantageously
affect the operation of the heat-exchanger according to the
invention in different ways. For instance, app~opriate
internal and/or external profiling of the tubes may increase
the internal and/or external heat-transfer surface, or
improve the resistance of the tube to buckling, and/or may
reduce the areas of contact between intersecting tubes.
Furthermore, the heat-transfer capacity may be increased by
the forming of vortices or noles in the relevant liquid,
at the profiled surfaces of the tubes. Moreover, more
compact and/or more dimensionally stable devices may be produced
with thin-walled tubes of non-circular shape.
- 16 -
l~Z8928
In order to ensure satisfactory heat-conductivity,
the walls of the tubes must be as thin as possible, but must
still be thick enough to meet mechanical demands. Tubes
found most satisfactory for most purposes have wall thic~nesses
of between 5 and lO0 ~m, while good heat-transmission values
have been obtained with wall-thicknesses of between 5 and 50 ~m,
and particularly good values with wall-thicknesses of between
5 and 20 ~m.
In order to obtain satisfactory heat-transmission
(K coefficient), the cross-sections of the thin-walled tubes
used must be of suitable size. In the case of tubes of
circular cross-section, outside diameters of between 0.04
and 4 mm, more particularly of between 0.04 and l mm, have
been found advantageous.
In the case of thin-walled tubes for the manu-
facture of the heat-exchanger according to the invention, the
coefficient of heat-transfer of the walls should be at least
1500 W/m K, particularly at least 4500 W/m2K. In this
connection the coefficient of heat-transfer of the walls of
-; 20 thin-walled tubes is to be understood to mean the quotient
of the heat-conductivity of the material used for the tubes,
measured in W/mK, and the wall-thickness of the said tubes
measured in metres.
The invention will now be described in more detail
w~th reference to the accompanying drawings in which:
FIGURES 1 to 7 show cross-sections through thin-
walled tubes of various shapes,
FIGURES 8 and 9 show longitudinal sections through
thin-walled tubes which are not designed as circular cylinders,
FIGURES lO and ll show a simplified schematic view
of the production of a multiJlayer wound member from a thin-
walled tube.
- 17 _
llZ8928
FIGURE 12 shows a simplified schematic view of a
longitudinal section through a spooled member of thin-walled
tubes having flange-like projections at its ends cast from a
casting composition,
FIGURES 13 to 15 show a simplified schematic view
of longitudinal sections through spooled members of various
shapes composed of thin-walled tubes having flange-like
projections cast from a casting composition at their ends,
FIGURE 16 shows a simplified view of a spooled
member from thin-walled tubes having only one flange-like
projection made of a casting composition arranged at its
end,
FIGURE 17 shows a simplified schematic view of a
spooled member having flange-like projections cast from a
casting composition at both its ends,
FIGURES 18 to 21 show a simplified schematic view
of embodiments of the heat exchanger according to the
invention using a spooled member made of thin-walled tubes,
FIGURES 22 to 24 show a simplified schematic view
of the production of a spooled member made of two thi~-walled
tubes,
FIGURE 25 shows a simplified schematic view of an
embodiment of the.heat exchanger according to the invention
using a spooled member produced according to Figures 22 to
24,
FIGURES 26 to 31 show a simplified schematic view
of various embodiments of banks of tubes produced from spooled
members each having differing cross-sectional shapes,
FIGURES 32 to 37 show a simplified schematic view
of the production of an embodiment of the heat exchanger accord-
ing to the invention from a substantially disc-shaped wound
member from thin-walled tubes.
.- 18 -
. ,
~128928
With-further reference to the drawing~, Figures 1
to 5 show, by way of example, cross-9ection~ of profiled thin-
walled tubes of a type which are suitable for the heat
exchanger according to the invention.
In the form illustrated in Figure 1, a thin-walled
tube has a substantially circular cylindrical cavity 27
while it has a rib-like projection 26 running in it~
longitudinal direction on its exterior, which can optionally
consist of a different material from the tube sheath.
The thin-walled tube illustrated in Figure 2 also
has a substantially circular cylindrical cavity 27 and
four rib-like projections 26 running in its longitudina~
direction, optionally made of a differing material.
The thin-walled tube illustrated in Figure 3 has a
substantially three-tabbed cros~-section, the cavity 27 having
a similar shape to the tube sheath 28 so that this thin-
walled tube has a wall of substantially constant thickness
over its circumference.
The thin-walled tube illustrated in Figure 4 has a
sheath 28 which is externally substantially circular and
has on its interior four rib-like projections 26 running in
the longitudinal direction of the thin-walled tube and pro-
jecting into its cavity 27, these projections being optionally
made of a different material from the sheath 28.
Figure 5 shows a thin-walled tube in which the
sheath 28 has a hexagonal annular cross-section and the
cavity 27 has a hexagonal cross-section.
Figure 6 shows a cross-section through~a tube con-
figuration which can be produced, for eYample, by fusing three
thin-walled tubes of round cross-section together on their
common lines of contact.
-- 19 --
~289Z8
Figure 7 shows a cross-section through a thin-
walled tube with a croqs member 29 arranged centrally inside
the thin-waIled tube and running in its longitudinal direction.
This thin-walled tube therefore has two cavities 27 of equal
size which are separated from each other by the cro~s member
29, run parallel to each other and have a semi-circular cross-
section.
Figure 8 shows a longitudinal section through a
thin-walled tube having an external diameter or circumference
which increases and then decreases again at optionally
regular intervals in itq longitudinal direction and having
an internal diameter or cavity circumference which decreases
and then increases again at optionally regular intervals in
its longitudinal direction. The thin-walled tube thus has
a sheath 28 whose wall thickness changes in the longitudinal
direction of the thin-walled tube.
Figure 9 shows a longitudinal section through a
thin-walled tube with a cross-section which increases at
optionally regular intervals in its longitudinal direction,
the wall thickness of the thin-walled tube remaining constant
in its longitudinal direction.
Figures 10 and 11 show a simplified schematic view
of a known device for the production of spooled members
which are suitable fora heat exchanger according to the
invention. The continuous thin-walled tube 1 supplied is
wound by means of a thread guide 2 which moves to and fro
onto a rotating perforated reel holder 3 so that a spooled
member 4 is produced which is made up in the manner of a coil
of several layers or portions of continuously supplied and
wound thin-walled tube 1 which crosses over at a predetermined
angle.
, .
- 20 -
.,
-
~28928
Figure 12 3hows a longitudinal section through a
spooled member 4 which is produced, for example, using a
device described with reference to Figures 10 and 11. The
spooled member 4 is provided at its two ends 5 with flange-
like projections 7 made of a curable casting composition
which has been brought into the desired shape by centrifugal
casting. The openings of the thin-walled tubes of the spooled
member 4 can be freed by severing a part of the flange-like
projections 7 along the lines A and B. The perforated reel
holder 3 ensures that the spooled member 4 is traversed
radially.
The spooled member 4 illustrated in a longitudinal
section in Fig~re 13 is formed by the uniform winding of a
- continuous thin-walled tube on a co~ically designed reel
holder 3 and thus has a conical shape itsel. With this
~pooled member 4, the ends of the individual tube portions
are freed by severing a portion of the flange-like projections
7 (as already described with reference to Figure 12).
The qpooled member 4 illustrated in the longitudinal
- 20 section in Figure 14 is produced by the uniform winding of a
continuous thin-walled tube onto a diabolo shaped reel holder
3 and therefore has a diabolo shape itself. In this spooled
member 4, the ends of the individual tube portions are
already freed by severing a portion of t~e flange-like pro-
jections 7 (as already described with reference to Figure 12).
The spooled member 4 illustrated in the longitudinal
; section in Figure 15 is produced by the uniform winding of
a continuous thin-walled tube onto a barrel-shaped reel
holder 3 and is thus barrel-shaped itself. With thi~ spooled
- 30 mémber 4, the ends of the individual tube portions are freed
by separating a portion of the flange-like projections 7 (as
already described with reference to Figure 12).
- 21 _
~12892~
The spooled member 4 illustrated in Figure 16 i9
produced by the uniform winding of a continuous thin-walled
tube on a circular cylindrical reel holder and thus has a
circular cylindrical shape itself. This spooled member 4 is
provided with a flange-like projection 7 only at one end so
that the ends of the individual tube portions of the spooled
member 4 are freed only on this one side by the severing of
portion of the flange-like projection 7 already described.
The path of flow of a fluid through the thin-
walled tube of a spooled me~ber of this type runs in the
manner of that of a U-shaped pipe. This means that the inlet
and outlet openings for the fluid lie in one and the same
plane in this spooled member.
Figure 17 shows a spooled member of the type pro-
duced when the flange-like projections 7 are partially severed,
for example, in the manner shown in Figure 12 along the
lines A-A and B-B.
Figure 18 shows the use of a spooled member 4 pro-
duced in the manner described with reference to Figures 10
to 12 in a heat exchanger according to the invention. The
spooled member 4 with the flange-like projections 7 is
arranged in a correspondingly dimensioned housing 10 in this
case. A first fluid 8 flows through the inlet nozzle 11 into
a di~tribution chamber 16 of the heat exchanger and passes
thence into the inlet openings of the thin-walled tubes
arranged in the spooled member 4, flows through them and
leaves them at the opposite end of the spooled member 4,
passe~ into a collecting chamber 17 of the heat exchanger and
leaves it through an outlet nozzle 12. It can also flow
through the thin-walled tubes in the opposite direction.
. ~
- 22 -
11289Z~3
A second fluid 9 flows through an inlet nozzle into a core
chamber 18 of the spooled member 4 which is sealed at its end
15, and flows through the spooled member 4 in the radial
direction from the interior outwards and passes into an
annular cylindrical collection chamber 19, whence it leave~
the heat exchanger through an outlet nozzle 14.
Figure 19 shows a heat exchanger according to the
invention in which the spooled member 4 is provided with a
partition wall 21 which is arranged in such a way, however,
that the free flow cross-section of the individual thin-
walled tubes is not interrupted thereby. A first fluid 8
traverses the heat exchanger in the same way as described
with reference to Figure 18. A second fluid 9 flows through
the inlet nozzle 13 of the heat exchanger into an annular
cylindrical distribution chamber 20, then traverses the right
half of the spooled member 4 in a radial direction from
the exterior inwards and enters the core chamber 18 of the
spooled member 4 which is sealed at both end faces 15. The
second fluid 9 then traverses the left half of the spooled
member 4 in a radial direction from the interior outwards
and passes into the annular cylindrical collection chamber
19, whence it leaves the heat exchanger through the outiet
nozzle 14.
Figure 20 shows a heat exchanger according to the
invention in which the thin walled tubes of the spooled
member 4 according to Figure 16 which are provided with
flange-like projection 7 only on one side and are cut away
and the inlet openings and the outlet openings of the
individual thin-walled tubes are each off~et by 180 relative
to each other, and thus face each other, i.e., are arranged
in a similar manner to that known from conventional heat
llZ8928
exchangers with U-shaped pipes. With thiR heat exchanger,
a first fluid 8 flows through the inlet nozzle 11 into the
distribution chamber 16,' passes thence into the intqrior of
the thin-walled tubes of the spooled member 4, traverses it
firstly in one direction and then in the sub~tantially
opposite direction and subsequently enters the collection
chamber 17 whence it leaves the heat exchanger again through
the outlet nozzle 12. The second fluid 9 flows through the
inlet nozzle 13 into the annular cylindrical distribution
chamber 20, whence it flows through the spooled mem~er 4 from
the exterior inwards in a radial direction and enters the
core chamber 18 of'the spooled member 4, which is sealed at'
the end 15, and thence leavesthe heat exchanger through the
outlet nozzle,14.
Figure 21 shows a heat exchanger according to the
invention which combines the essential features of the
spooled member shown in Figures 19 and 20. In this case,
the first fluid 8 1OWS through the thin-walled tubes of the
spooled member 4 in the manner described with reference to
Figure 20 and the second fluid 9 flows round the thin-walled
tubes of the spooled member 4 in the manner described with
reference to Figure 19. '
Figures 22 to 24 'show a simplified schematic view
of a device for the production of a ~pooled member 4 from
two thin-walled tubes 1 which are supplied separately from two
: . .
spoolq 6 but are wound simultaneously onto a common reel
holder 3. By arranging the thread guides 2 offset in the
longitudinal direction of the ~pooled member 4 in the manner
~hown in Figures 23 and 24, it is possible to produce a
30 spooled member 4 in which the respective layers of the two
thin-walled tubes 1 are wound offset relative to each other
. - 24 -
1~2892~3
in the longitudinal direction of the spooled member 4 90 a~
to form a region 22 at each of the ends of the spooled member
4 which is formed only by one of the two thin-walled tubes,
A spooled member which has the inlet and the outlet opening~
for a first fluid on one side and those for a second fluid
at the opposite end is produced by removing these two
regions 22.
The use of a spooled member produced in this way in
accordance with Figures 22 to 24 in a heat exchanger accord-
ing to the invention is illustrated in Figure 25. In addition,
the spooled member 4 is located in a solid or liquid sub-
stance 23 which is a good conductor of heat in this embodi-
ment illustrated in Figure 25. A heat exchanger of thiq
type allows, for example, the heat to be transferred from
a first fluid 8 to a second fluid 9 utilising the good heat
conducting properties of the substance 23, the fluid 8 flow-
ing through the corresponding layer~ of the spooled member 4
formed by a th.in-walled tube, for example, in the manner
illustrated in Figure 20. In Figure 25, this path of fl.ow
iB indicated schematically as a broken llne, while the second
fluid 9 follows a path of flow which is a mirror image of
it, which is indicated by the continuous line in Figure 2S.
. Figure 26 shows a spooled member 4 with flange-
like projections 7 arranged at its two ends, the flange-
like projections 7 (like those of the spooled member 4
illustrated in Figures 12 to 21) having a larger external
circumference than the spooled member 4. The flange-like
projections 7 and the spooled member 4, however, have an
elliptical annular cross-section in this case.
_ 25 -
1121~92~
Figure 27 shows that a spooled member 4 can be cast
not only at its ends and cut up accordingly in the manner
de~cribed above but can also be ca~t along one or more of
its generating lines. In the embodiment illustrated in
Figure 27, the thin-walled tubes consequently merge into
two circular cylindrical cavities 24 and 25 which are
surrounded by a wall consisting, for example, of cast resin~,
which, as explained with reference to the Figures already
described, act as distribution and collecting chambers for
the fluid flowing through the thin-walled tubes.
Figure 28 shows a cross-section through a spooled
member 4 which is obtained if thin-walled tubes are wound
on a reel holder 3 with a rectangular cross-section having
rounded corners.
Figure 29 showæ a cross-section through a spooled
member 4 which is obtained if a spooled member 4 according
to Figure 28 is cast, for example, in cast resin, aiong two
of its generating lines in the manner described with
reference to Figure 27 and the openings of the thin-walled
tubes are then freed in the manner already described.
Figure 30 shows a cross-section through a spooled
member 4 which can also be produced from the spooled member
4 illustrated in Figure 28, and Figure 31 shows one which is
obtained in a manner similar to that described in Figure 27
from a spooled member 4 of circular annular cross-section.
The embodiments according to the invention illustrated
in Figures 27 to 31 are eminently suitable for heattransfer
from a Liquid medium to a gaseous medium (for example, as a
car radiator) or vice versa, the liquid medium preferably
flowing through the thin-walled tubes and the gaseous medium
flowing round the thin-walled tubes.
`` llZ8928
Figure 32 shows a cross-section through an annular
coil holder 31 of the type which is suitable, for the pro-
duction of a disc-shaped coiled member from thin-walled
tubes.
Figure 33 shows a possible arrangement for the
- individual thread ~ortions, for example, of a continuously
wound thin-walled tube`, on the annular coil holder 31. In
this case, the tube protions can be arranged in se~eral
superimposed layers which cross each other several time~.
By casting the external portion of the annular coil holder
31, for example, in a curable casting composition and then
removing a part of the annular casting-composition-projection
to the region of the turned back parts 32 of the tube portions,
the thin-walled tube 1, which i9 initially continuous, ïs
divided into a plurality of equally long tube portions
arranged in several layers and crossing each other several
times and the openings in the individual tubè portions are
freed at each severing point. The external diameter of the
unworked part of the annular casting composition projection
is thus generally equal to, or slightly smaller than, the
external diameter of the annular coil holder 31.
Figure 34 shows a sectional illustration of the
plan view of a disc-shaped embodiment of the heat exchanger
according to the invention in which a wound member 4
according to Figure 33 has been used. By suitably arranging
the inlet nozzle 11 and the distribution chambers 16 as well
as the collection chambers 17 and the outlet nozzle 12 for
a first fluid 8 and the inlet nozzle 13 and the distribution
chambers 20 as well as the collection chambers 19 and the
outlet nozzle 14 for the second fluid 9, a heat exchanger
having a total of two inlets and two outlets for each of the
1128928
two fluids 8 and 9 is obtained. In this case, the liquid
stream entering the heat exchanger through the inle~ at any
time is divided so that only half of each partial atream of
fluids 8 and 9 reaches the two outlets communicating with
the corresponding inlet at any time and combines there with
one of the halves of the other partial stream of fluids 8
and 9. Figure 34 shows this path of flow by arrows and
four tube portions drawn as thick lines.
Figure 35 shows a cross-section along the line
XXV - XXV through Figure 34. The annular coil holder 31,
the annular projection 7 made of a curable casting com,
position, the wound member 4 a~ well as the two opposing
distribution chambers 16 for the first fluid 8 can be seen.
Figure 36 shows another possible arrangement of
a continuous thin-walled tube 1 on an annular coil holder 31
for the production of a tube winding for disc-shaped em~odi-
ments of the heat exchanger according to the invention.
Figure 37 shows a cross-section through a heat
exchanger according to the invention in which a wound mem~er
according to Figure 36 has been used. The openings in the
~ individual tube layers have been freed here, as already
;~ described with reference to Figures 32 to 35. In this
embodiment, the first fluid 8 flows through the inlet nozzle -
11 into the distribution chamber 16, then traverses the thin-
walled tubes of the wound member 4, enters the collection
chamber 17 and leaves the heat exchanger through the outlet
nozzle 12. The reference numerals of the remaining parts of
this heat exchanger correspond to the parts described by way
of example with reference to Figure 34. An exemplary second
fluid participating in the heat transfer traverAes the heat
exchanger illustrated in Figure 37 in substantially the axial
direction thereof.
A 28 _
11289Z8
Whereas the heat exchanger illustrated in Figure
37 is thus suitable for transferring heat from one medium
to another, a total of three media can participate in the
heat transfer in the heat exchanger illustrated in Figure~
34 and 35. With the heat exchanger illustrated in Figures
34 and 35, the third medium could be, for example, a solid
or liquid substance which is a good conductor of heat
and which surrounds the thin tubes from the outside or a
third fluid which flows through the heat exchanger in its
axial direction.
The use of the disc-shaped wound member described
by way of example with reference to Figures 33 and 36 is
; not restricted to the production of substantially disc-
shaped heat exchangers but rather it is possible according
to the invention to superimpose a plurality of these wound
members and, in this way, to allow an optional number of
fluids to participate in the transfer of heat.
Thus it has now been found that the specific heat
transfer capacity of the thin-walled tubes can also be used
in heat tran~fer apparatus (heat exchangers), with consider-
able improvement. Thin-walled tubes of this type which can
be produced by a rapid spinning process are in fact parti-
cularly suitable for heat transfer if they have properties
and/or a shape which increase their thermal conductivity
and/or their heat transmission, and if they are arranged,
utilising their flexibility, in such a way that the heat
exchange apparatus produced from thin-walied tubes of this
type have a greater resistance to external mechanical stresses
so that they guarantee an undiminished heat transfer capacity
even after prolonged operation.
_ 29 -
~28928
The invention thus permits an improvement in the
thermal conductivity, heat transmission and heat transfer
properties of thin-walled tubes, and the provision of a heat
transfer apparatus produced from such tubes which, with regard
both to its production and to its serviceability and heat
transfer capacity, does not have the disadvantages of the
heat exchangers produced from known hollow threads.
.
:,
- 30 -
