EP0069262A1 - Apparatus by which heat is transmitted through hollow fibres - Google Patents

Abstract

1. An apparatus in which heat is transmitted from a first liquid to a second liquid through the walls of hollow filaments and in which the hollow filaments open into distributing or collecting pipes, which have connecting parts for the supply or discharge of the fluid and to which the end sections of the hollow filaments are connected in a fluid-tight manner outwards by means of a packing composition, characterised in that the hollow filaments are supported by a support frame (2, 3, 6), which is at least partially formed by the distributing or collecting pipes (2; 3), that at least a part of the hollow filaments (1) is curved or bent once continuously or discontinuously, that the hollow filaments (1) are arranged in at most two layers, that in the two-layer arrangement of the hollow filaments (1), the hollow filaments (1) of the first layer cross the hollow filaments (1) of the second layer and contact the crossing hollow filaments (1) at the crossing points, that the hollow filaments (1) of each layer are supported by support rods (7), which cross the hollow filaments (1) and which are tightly connected to the support frame (2, 3, 6) and the hollow filaments (1) at the contact points thereof, that the hollow filament (1) of each layer are arranged at a spacing from each other and that the maximum excursion of each curved or bent hollow filament (1) is a twentieth (1/20) to a fifth (1/5) of the distance between the two ends thereof and that the hollow filaments lie in a spatially curved or arched surface.

Description

The invention relates to a device in which heat is transferred from a first fluid to a second fluid through the wall of hollow fibers.

A heat exchanger of the type mentioned at the outset is known, in which the hollow filaments are arranged in two planes, the hollow filaments of each plane being arranged at equal distances from one another and running parallel to one another, and consequently being rectilinear, and in which the hollow filaments are disposed in common distribution or Collector pipes open, which have the connections for the fluid supply or discharge and can be designed as a support frame and with which the end sections of the hollow filaments are connected in a liquid-tight manner by means of an investment material. With this

known heat exchangers, the hollow filaments of the two levels are arranged at right angles to one another and touch at their crossing points. Furthermore, this known heat exchanger has support rods for the hollow fibers, which are arranged at intervals from one another, run at right angles to the hollow fibers to be supported and are firmly connected to them at their crossing points. The support rods have a larger diameter than the hollow threads.

This known heat exchanger has proven itself particularly well for heat transfer between a gaseous medium, for example air, which flows around the hollow filaments and a liquid medium, for example water which flows through the hollow filaments. As expected, the best results were achieved when the gaseous medium flowed around the hollow fibers perpendicular to their longitudinal axis, i.e. transversely. On the other hand, when this known heat exchanger is used outdoors at high wind speeds, problems occasionally occurred due to the high wind forces which occur, in particular caused by wind gusts. In addition, optimal heat transfer could only be achieved if this known heat exchanger was aligned with the respective, possibly constantly changing, wind direction.

The present invention is therefore based on the object of providing a device of the type described at the outset which is also suitable for high wind speeds and which ensures an essentially uniform heat transfer even in the case of changing wind directions.

This object is achieved with a device in which the hollow threads open into distributor or collecting pipes, which have connections for the fluid supply or drainage and can be designed as a support frame, and with which the end sections of the hollow threads are connected to the outside in a liquid-tight manner by means of an investment material are, in which according to the invention at least some of the hollow threads are present in a continuously or discontinuously curved or curved shape. The hollow filaments can thus, for example, be designed in the form of a circular arc, be angled once or several times, run in a zigzag shape or be shaped similarly. It is important that at least some of the hollow threads, but preferably all hollow threads, do not run in a straight line, but rather continue in at least one changed direction.

If you imagine the two ends of each of the hollow threads of the device according to the invention connected by a straight line (chord) and the greatest distance of the hollow thread from this connecting line (chord) is called the maximum deflection, particularly good results are achieved if the maximum deflection of the hollow threads of the device according to the invention about a twentieth (1/20) to a fifth (1/5), in particular about a tenth (1/10) of the distance of the two ends of each hollow thread from each other, that is the length of the connecting straight line (chord) , is.

The number of hollow threads of the thread sheet forming the heat transfer surface of the device according to the invention can be chosen arbitrarily, the hollow threads of each thread sheet not necessarily having the same or a similar shape must have, but are generally the same or similar shape.

Particularly good results are achieved if the sheet of hollow fibers is not in one plane, but in a spatially curved surface, for example the shape of the surface of a spherical cap, part of a cylinder jacket, a roof, a dome, a folding wall, a truncated pyramid and the like Has.

In an embodiment of the invention, the hollow fibers can be arranged one above the other in several groups, each group advantageously being able to consist of one or two hollow fiber layers. The hollow threads of a layer are expediently arranged at constant distances from one another, but can also spread out in a fan shape. The number of hollow threads can also be different in the different layers. Whatever the most expedient embodiment of such a hollow fiber layer may be, the arrangement of the hollow threads of such a hollow thread layer is in any case such that the hollow threads could also be described as being arranged side by side in the broadest sense. In the case of two hollow fiber layers per hollow fiber group, the hollow threads of the first layer can cross the hollow threads of the second layer and touch them at the crossing points. In the case of a plurality of hollow fiber groups, these are advantageously arranged at a sufficient mutual distance from one another which can be determined by simple experiments.

Each hollow fiber layer or group advantageously has its own, possibly designed as a support frame, distributor and header pipes for the fluid supply _or w. -Discharge, which in turn are connected to a common inflow or outflow line. Hollow thread layers or groups of this type designed according to the invention, including their distributor and collecting tubes, can be designed in a particularly advantageous manner as module units which can be arranged one above the other or side by side in any number. For this purpose, it is particularly advantageous if the common inflow and outflow lines are formed by pipe sockets or connections which cooperate with one another in the manner of a plug connection and are arranged on the distributor or collecting pipes. These plug-in connections can be designed to be detachable and self-sealing or else so that after the module units have been joined together by welding, gluing or the like, they cannot be releasably connected to one another in a fluid-tight manner. The stack-shaped embodiment of the device according to the invention formed in this way can have a square, rectangular, hexagonal, round or any other shape-shaped cross section or cover a base area of the same shape in plan view.

The hollow fiber layers or groups can be connected individually or in groups in series or in series, mixed forms also being possible, for example parallel connection of the hollow thread layers of each hollow thread group but series connection of the hollow thread groups.

The hollow thread layers or groups arranged one above the other or next to one another can have a curvature in the same direction, but can also be curved alternately in opposite directions, for example in mirror image. Two oppositely curved hollow fiber layers or groups, the ends of which in one In the case of an arrangement covering the entire surface, the plane can roughly form the shape of a pillow, a lens, a cylinder, a sphere, etc.

By means of simple experiments, the practical design and arrangement of the hollow fiber layers or groups forming the device according to the invention, which can be readily determined, succeeds in keeping the wind noise generated when the hollow fibers flow around and thus in a low-noise, environmentally friendly manner. device to arrive.

The shape of the hollow fiber layers or groups can be achieved by appropriate design of the distributor or header pipes and / or of support rods, which also give the hollow fiber coulters great dimensional stability. These support bars are preferably arranged so that they cross at least one DER hollow fiber layers and at their loading rührungs ^p unkten with the hollow fibers by welding, gluing and the like are fixedly connected. The support rods expediently have a larger diameter than the hollow threads and are arranged at greater distances from one another than these. At their ends, the support rods are advantageously firmly connected to the distributor or header pipes. The support rods can be preformed before they are installed or can be clamped in an arc, for example when installed between two distributor or header pipes, by a corresponding excess length.

All hollow threads suitable for heat transfer can be used to produce the device according to the invention, these after a dry or wet spinning or an extrusion process. For the purposes of the present invention, the term hollow thread also includes so-called hollow fibers, thin tubes, thin-walled tubes, capillaries, tubes, plastic tubes and the like. Although the embodiments of the device according to the invention with non-metallic hollow threads are generally preferred, the teaching of the present invention can, however, also be readily applied to devices with appropriately sized metallic tubes.

The cross-sectional shape of the hollow filaments used can be of any type, the size of the cross-section of the hollow filaments as well as their wall thickness up and down being subject to no restrictions. The cross-sectional shape, the wall thickness and the size of the cross-section of the hollow filaments can also change along the length of the hollow filaments. Hollow threads with a circular cross-section can have, for example, an outer diameter of 800 μm up to 5 mm and above. The wall thickness of the hollow filaments can be, for example, 30 to 200 μm.

For the manufacture of the device according to the invention, those hollow threads have proven to be particularly advantageous which have a heat transfer coefficient in the range from 15 to 200 W / m ² K and above, it also being possible to use hollow fibers which have improved thermal conductivity properties through the incorporation of metal, Have graphite and the like in dust or powder form. Alternatively or additionally, the hollow filaments can also contain fillers, additives, stabilizers, carbon black, dyes and the like. By using porous or microporous hollow filaments, the application spectrum of the device according to the invention can be expanded in an advantageous manner.

For embedding the ends of the hollow fibers, conventional adhesives, curable casting compounds, casting resins, special cements and the like can be used, it being also possible to use investment materials which immediately dissolve or melt on the surface immediately after the first contact with the hollow fibers. The embedding of hollow threads or their end sections is known per se and therefore need not be explained here any longer.

The size of the device according to the invention is not subject to any restrictions within the usual dimensions.

However, it has been shown that if the hollow threads are arranged too closely, the flow resistance for the fluid flowing around the hollow threads increases considerably, so that the heat transfer performance drops considerably. Too large a hollow thread spacing in turn leads to unnecessarily large dimensions of the device according to the invention. For a particularly expedient design of the device according to the invention, it is therefore proposed to choose the center distances of the hollow threads so that between two adjacent hollow threads this is 1.7 to 10 times their diameter, in particular 2.5 to 3.3 times is. The clear distance between two adjacent hollow threads should expediently be 0.5 to 15 mm, in particular 1 to 10 mm.

The dimensions for the distributor or collector pipes depend on the one hand on the number of hollow threads emanating from or emptying into them and their dimensions, on the other hand on the total through the hollow threads flowing amount of fluid, because it is undesirable that unnecessarily high pressure drops occur in the manifold and manifolds. Furthermore, the dimensioning of the distributor and header pipes depends on whether they are also intended to serve as a support frame and should give the device according to the invention a stability that meets the requirements, or whether this should be brought about by other structural measures and devices. Depending on the requirements placed on the distributor or header pipes, they can thus also be provided, for example, with stiffening ribs or the like running in their longitudinal direction. It is also possible to give the pipes mentioned a shape which is favorable in terms of flow technology, or to achieve the same result by appropriately encasing them.

In the context of the present invention, it is finally also possible to let the hollow threads hang down as loose threads between the distributor and collecting pipes in loose loops, but here, too, in order to maintain constant hollow thread spacings, rods extending transversely to the hollow threads can be arranged, which can be connected to the Hollow threads are firmly connected at the crossing points.

In addition to the hollow fiber groups formed from individual hollow fiber layers, suitable hollow thread groups can also be formed by hollow fiber fabrics. It is also possible to use hollow fiber mats in which the distance between the hollow threads is determined by knitted threads, tapes or the like.

• Die Figuren la und lb eine Ausführungsform der erfindungsgemäßen Vorrichtung in Draufsicht mit zick-zack- bzw. wellenförmig ausgebildeten Hohlfäden,
• Figur 2 in perspektivischer teilweise geschnittener Darstellungsweise eine Ausführungsform der erfindungsgemäßen Vorrichtung in Form eines Zylindermantelabschnittes,
• Figur 3 in einem vergrößerten Ausschnitt aus Figur 2 eine Ausführungsform der Steckverbindung,
• Figur 4 eine Ausführungsform der erfindungsgemäßen Vorrichtung in Draufsicht,
• Figur 5 eine Ausführungsform der erfindungsgemäßen Vorrichtung im Querschnitt,
• Figur 6 eine Ausführungsform der erfindungsgemäßen Vorrichtung mit übereinanderangeordneten spiegelbildlich, also gegensinnig, gebogenen Hohlfäden,
• Figur 7 eine Ausführungsform der erfindungsgemäßen Vorrichtung mit übereinanderangeordneten gegensinnig, jedoch nicht spiegelbildlich gebogenen Hohlfäden,
• Figur 8 eine Ausführungsform der erfindungsgemäßen Vorrichtung, bei welcher mehrere gleichsinnig gekrümmte Hohlfadenlagen übereinander angeordnet sind,
• Figur 9 eine zylinderförmige Ausführungsform der erfindungsgemäßen Vorrichtung,
• Figur 10 eine Ausführungsform der erfindungsgemäßen Vorrichtung in Form einer Faltwand,
• Figur 11 eine Ausführungsform der erfindungsgemäßen Vorrichtung, bei welcher mehrere zylinderschalenförmige gleichsinnig gekrümmte Hohlfadengruppen übereinander angeordnet sind,
• Figur 12 eine Ausführungsform der erfindungsgemäßen Vorrichtung, bei welcher mehrere gegensinnig, jedoch nicht spiegelbildlich gekrümmte Hohlfadengruppen übereinander angeordnet sind,
• Figur 13 eine Ausführungsform der erfindungsgemäßen Vorrichtung, bei welcher mehrere spiegelbildlich gekrümmte Hohlfadengruppen übereinander angeordnet sind,
• Figur 14 eine Ausführungsform der erfindungsgemäßen Vorrichtung, bei welcher mehrere gleichsinnig gekrümmte kugelschalenförmige Hohlfadengruppen übereinander angeordnet sind,
• Figur 15 eine Ausführungsform der erfindungsgemäßen Vorrichtung, bei welcher zwei spiegelbildlich gekrümmte kugelschalenförmige Hohlfadengruppen übereinander angeordnet sind,
• Figur 16 in vereinfachter schematischer Darstellungsweise die Reihenschaltung erfindungsgemäß ausgebildeter Hohlfadengruppen,
• Figur 17 in vereinfachter schematischer Darstellungsweise die Parallelschaltung erfindungsgemäß ausgebildeter Hohlfadengruppen,
• Figur 18 eine Ausführungsform der erfindungsgemäßen Vorrichtung, bei welcher die Hohlfäden in losen Schlaufen zwischen den Verteiler- und Sammelrohren herunterhängen,,
• Figur 19 in Draufsicht eine weitere Ausführungsform der erfindungsgemäßen Vorrichtung.

The invention will now be explained in more detail with reference to the drawing. Show it:

• Figures la and lb an embodiment of the device according to the invention in plan view with zigzag or wavy hollow threads,
• FIG. 2 shows a perspective, partially sectioned representation of an embodiment of the device according to the invention in the form of a cylinder jacket section,
• FIG. 3 shows an embodiment of the plug connection in an enlarged detail from FIG. 2,
• FIG. 4 shows an embodiment of the device according to the invention in plan view,
• FIG. 5 shows an embodiment of the device according to the invention in cross section,
• FIG. 6 shows an embodiment of the device according to the invention with hollow threads which are arranged one above the other in mirror image, ie in opposite directions,
• Figure 7 shows an embodiment of the device according to the invention with one another arranged hollow threads that are bent in opposite directions, but not in mirror image,
• FIG. 8 shows an embodiment of the device according to the invention in which a plurality of hollow thread layers curved in the same direction are arranged one above the other,
• FIG. 9 shows a cylindrical embodiment of the device according to the invention,
• FIG. 10 shows an embodiment of the device according to the invention in the form of a folding wall,
• FIG. 11 shows an embodiment of the device according to the invention, in which several cylindrical shell-shaped hollow thread groups are arranged one above the other,
• FIG. 12 shows an embodiment of the device according to the invention in which a plurality of hollow thread groups which are curved in opposite directions, but not in mirror image, are arranged one above the other,
• FIG. 13 shows an embodiment of the device according to the invention, in which a plurality of hollow thread groups which are curved in mirror image fashion are arranged one above the other,
• FIG. 14 shows an embodiment of the device according to the invention, in which a plurality of hollow fiber groups in the form of spherical shells are arranged one above the other,
• FIG. 15 shows an embodiment of the device according to the invention, in which two spherical shell-shaped hollow thread groups are arranged one above the other,
• FIG. 16 shows a simplified schematic representation of the series connection of hollow fiber groups designed according to the invention,
• FIG. 17 shows, in a simplified schematic representation, the parallel connection of hollow fiber groups designed according to the invention,
• Figure 18 shows an embodiment of the device according to the invention, in which the Hang hollow threads in loose loops between the distributor and collector pipes,
• Figure 19 is a plan view of another embodiment of the device according to the invention.

In Figure la, the hollow threads 1 are zigzag-shaped, but lie in one plane. The hollow threads 1 open into the distributor pipe 2, which has the connection 4 for the fluid supply, and in the collecting pipe 3, which has the connection 5 for the fluid discharge. To form a support frame for the coulter made of zigzag-shaped hollow threads 1, the distributor pipe 2 and the header pipe 3 are firmly connected to one another by struts 6. Furthermore, support rods 7 extending transversely to the hollow threads 1 are shown in FIG. 1 a, which are firmly connected at the intersections with the hollow threads 1 and with the struts 6. The support rods 7 each cross the hollow threads 1 at the point at which the hollow threads 1 are curved discontinuously, that is to say continue in the changed direction. In the context of the present invention, the hollow threads 1 shown in FIG. 1 a can also be referred to as curved repeatedly.

The embodiment of the device according to the invention shown in FIG. 1b differs from the one shown in FIG. 1 a essentially only in that the hollow threads 1 are wave-shaped, that is to say are continuously curved several times.

In the embodiment shown in Figure 2 embodiment of the apparatus according to the invention consisting of two layers of intersecting _H ohlfäden 1 hollow fiber group formed in the shape of a cylinder jacket section formed. The two hollow fiber layers are connected in parallel and the distributor tube 2 forms, together with the header tube 3, a support frame which ensures the above-mentioned shape of the hollow fiber group. The connections 4; 5 for the fluid supply and drainage are respectively directed upwards and downwards, so that a stacking of several of the embodiment of the device according to the invention shown in Figure 2 is possible, after assembly the connections for the fluid supply 4 then the common inflow line and the connections for the fluid drain 5 result in the common drain line. At points 10 and 11, the tubes 2 and 3 are sealed against each other.

In Figure 3, the connections 4 and 5 shown in simplified form in Figure 2 are shown enlarged. The illustration makes it clear how the connections 4 and 5 are inserted into one another when stacking several embodiments of the device according to the invention, as is shown, for example, in FIG. 2. After assembly, the connections 4a and 4b can be firmly connected to one another by gluing or welding. The same applies to the correspondingly designed, but not shown, connections for fluid drainage. Instead of the embodiment of the cooperating connections 4a and 4b shown in FIG. 3, commercially available detachable or non-detachable and simple pipe sockets can also be used for the purpose described here, for example so-called quick-action couplings.

In the embodiment of the device according to the invention shown in FIG. 4, all parts correspond to their position numbers in accordance with the parts already described in FIGS. The view shown in FIG. 4 results, for example, from a top view of the embodiment of the device according to the invention shown in FIG. Only the connection 4 for the fluid supply and the connection 5 for the fluid discharge are arranged in the embodiment shown in FIG. 4 in a slightly changed manner.

In the embodiment of the device according to the invention shown in FIG. 5, the hollow filaments 1 are bent twice discontinuously, these bends being brought about by the support rods 7 arranged at a corresponding point. The hollow fiber layers arranged one above the other are curved in the same direction, each hollow fiber layer forming the shape of part of the jacket of a polyhedron with a polygonal cross section, that is to say, in the sense of the present invention, a spatially curved surface.

The remaining parts shown in the figure correspond to their position numbers according to the parts described in the previous figures.

In FIG. 6, the hollow fibers 1 of each hollow fiber layer are curved inconsistently once by a supporting rod 7, with adjacent hollow fiber layers being curved in mirror image. Two hollow fiber layers each open into a common distributor pipe 2 or collecting pipe 3. The hollow thread shown in FIG. 6 layers can also be described as roof-shaped.

The hollow fiber layers / hollow fiber groups shown in FIG. 7 are also once discontinuously curved, that is to say they are roof-shaped, with the hollow thread layers / hollow fiber groups being curved in opposite directions but not in mirror image in the embodiment shown in FIG. The embodiment of the device according to the invention shown in FIG. 7 is, for example, excellently suitable for outdoor use, since it ensures an essentially constant heat transfer performance even in changing wind directions. It is obvious that several of the embodiment of the device according to the invention shown in FIG. 7 can also be arranged one above the other, whereby a correspondingly designed system of plug connections can also be used here. It goes without saying that by changing the maximum deflection of the hollow filaments, as defined above, the "angle of the roof gable" of the roof-shaped hollow filament sheet can be changed in a simple manner and adapted to the given requirements.

In the embodiment shown in FIG. 8, a plurality of hollow fiber layers / hollow fiber groups 1 which are continuously curved in the same direction are arranged one above the other. The distributor pipes 2 and the collecting pipes 3 of each hollow fiber layer / hollow fiber group 1 are again connected to a common inflow line 8 or outflow line 9. Here, too, plug connections can be used, as have already been described in FIGS. 2 and 3.

In view of the previous description of the figures, there is no need for a further detailed description of FIGS. 9 to 15 or 18, in which all parts correspond to their position numbers corresponding to the parts of the figures described so far. However, it should also be pointed out that the embodiments of the device according to the invention shown in FIGS. 9, 12, 14 and 15 are also particularly suitable for changing wind directions, wherein — and this applies to all the embodiments shown — any number of the embodiments shown are stacked on top of one another or can be arranged side by side.

In the embodiment shown in FIG. 16, a total of 3 exchange units are connected in series, the hollow fiber layers of each unit being able to be connected in parallel, as shown in FIG.

In FIG. 17, three exchange units designed according to the invention are connected in parallel, the individual hollow fiber layers of each exchange unit being able to be connected in parallel as shown in FIG. 4, but may also be in series.

In the figures 7, 10, 11, 12, 13, 14 and 15, only the hollow fibers 1 and _H were used to simplify or hollow thread groups ohlfadenlagen in a variety of embodiments shown, while the remaining necessary in practice for the functioning of the device according to the invention parts (2; 3; 4; 5; and optionally 4a; 4b; 5a; 5b; 6; 7; 8; 9; 10 and 11), as shown in the other figures and described above, have been omitted.

In the embodiment of the device according to the invention shown in FIG. 19, six hollow fiber groups, each consisting of two hollow fiber layers or groups, which are curved in opposite directions and mirror images of one another, were arranged in a star shape around the common collecting tube 3. Two such hollow fiber groups are shown, for example, in FIG. 13, but are arranged one above the other there. Each pair of hollow thread groups belonging together leads into a common distributor pipe 2. All distributor pipes 2 are connected to one another by a common inflow line 8, into which fluid can enter via the connection 4. This embodiment is particularly well suited for changing flow direction / wind direction.

Claims (15)

_1st Device in which heat is transferred from a first fluid to a second fluid through the wall of hollow fibers and in which the hollow fibers open into distributor or header pipes, which may be designed as support frames, which have connections for the fluid supply or discharge and with which the end sections of the hollow filaments are fluid-tightly connected to the outside by means of an investment material, characterized in that at least some of the hollow filaments (1) are curved or bent at least once continuously or discontinuously. 2. Device according to claim 1, characterized in that the hollow threads (1) do not lie in one plane, but in a spatially curved or curved surface. 3. Device according to claim 1 and 2, characterized in that the maximum deflection of each curved or curved hollow thread (1) is one twentieth (1/20) to one fifth (1/5) of the distance between its two ends. 4. The device according to claim 3, characterized in that the maximum deflection is approximately one tenth of the distance of the two ends of each hollow thread (1). 5. Apparatus according to claim 1 to 4, characterized in that the hollow threads (1) are arranged in several groups one above the other or side by side, each hollow thread group consisting of one or two hollow thread layers and the hollow thread groups being arranged at a distance from one another. 6. The device according to claim 5, characterized in that each hollow fiber group consists of two hollow fiber layers, the hollow fibers (1) of the first layer crossing the hollow threads (1) of the second layer and the intersecting hollow threads (1) to each of the hollow thread groups Touch crossing points. 7. Apparatus according to claim 5 and 6, characterized in that each hollow fiber layer or group has its own distributor and collecting pipes (2; 3) for the fluid supply or drainage, which in turn to a common inflow or outflow line ( 8; 9) are connected. 8. The device according to claim 5 to 7, characterized in that the hollow fiber layers or hollow fiber groups are alternately curved in opposite directions. 9. The device according to claim 1 to 8, characterized in that the hollow fiber layers or groups are supported by appropriately shaped the hollow threads (1) at least one layer of each of the hollow fiber groups supporting rods (7) and the hollow threads (1) with the support rods ( 7) are firmly connected at their points of contact. 10. The device according to claim 1 to 9, characterized in that the center distance between two adjacent hollow threads (1) is 1.7 to 10 times their diameter. 11. The device according to claim 10, characterized in that the center distance between two adjacent hollow threads (1) is 2.5 to 3.3 times their diameter. 12. The apparatus according to claim 1 to 11, characterized in that the clear distance between two adjacent hollow threads (1) is 0.5 to 15 mm. 13. The apparatus according to claim 12, characterized in that the clear distance between two adjacent hollow threads (1) is 1 to 10 mm. 14. The apparatus according to claim 1, characterized in that the hollow threads (1) hang as a thread sheet between the distributor and collecting pipes (2; 3) in loose loops, with spacers (7) extending transversely to the hollow threads (1) in order to maintain constant hollow thread spacings ) are arranged. 15. The apparatus according to claim 1 to 14, characterized in that the hollow threads (1) are porous or microporous.

Images