EP0225533A1 - Plate heat exchanger - Google Patents

Abstract

The invention relates to a surface heat exchanger which consists of a plate (1) made of heat-conducting material and at least one tube (2) connected to it, in particular in a meandering shape, wherein a heat exchange medium can flow through the tube. In the new surface heat exchanger, the plate is provided with slots (3, 4, 5, 6, 23), the width (b) of which is adapted to the diameter (d) of the tube (2). The tube (2) is inserted approximately flush with the plate (1) in the slots (3, 4, 5, 6, 23) and is held in a form-fitting manner on the slot edges (8) by means of deformations (7) extending transversely to its axis. The width (b) of the slots is expediently chosen to be somewhat smaller than the tube diameter (d), so that the tube with its largest diameter is seated diametrically firmly in the plate and is held in the plate by the pinches (g) acting as a positive fit.

Description

The invention relates to a surface heat exchanger consisting of a plate made of heat-conducting material and at least one tube connected to it, in particular in a meandering shape, through which a heat exchange medium can flow.

Surface heat exchangers of this type are known (DE-GM 83 04 603). In this belt, meandering bent coils are provided, which are fastened to carrier plates, which are preferably made of aluminum or wrought aluminum alloys, in that cramps are punched out of the plane of the carrier plates and placed around the pipes. The pipes fixed in this way to the plate, which have a triangular cross-section for better fastening, can then be covered by a second plate. The disadvantage of these designs is that the eyelets and retaining cramps pose a risk of injury when installing such a surface heat exchanger, which is why the second cover plate must also be provided, as a rule, and that the heat transfer between the tube and plate is not due to the relatively small contact surfaces between the cramps and the tube is sufficient.

It is also known to manufacture surface heat exchangers by (DE-OS 33 08 329) that the coil is glued to the support plate. The bad heat transfer between the coil and the plate is also disadvantageous here because the adhesive has only a low thermal conductivity. It is also disadvantageous that the tube coil and carrier plate have to remain clamped to one another during the curing process of the adhesive. This is cost-intensive and, due to the curing time, series production does not appear to make sense. In addition, such an adhesive connection is not reliable enough for highly stressed products, such as for use in motor vehicles.

The invention is therefore based on the object of proposing a surface heat exchanger of the type mentioned at the outset is easy to manufacture, but still ensures good heat transfer between the tube and the support plate.

Based on the consideration that it is not sufficient for this to arrange the coil on one side of a carrier plate, the invention is that the plate is provided with slots, the width of which is adapted to the diameter of the tube, and that the tube is approximately flush used for the plate in the slots and is held in a form-fitting manner on the slot edges by means of deformations running transversely to its axis. This configuration creates continuous contact surfaces between the tube and the support plate on opposite outer sides of the tube, which ensure a heat transfer that is as good as that between the fins attached to a tube. However, the production of the new surface heat exchanger requires neither an adhesive nor a soldering process and can be carried out in a simple manner. The heat transfer between the tube and plate can also be improved in that the width of the slots is selected to be somewhat smaller than the tube diameter. As a result, when the pipes are positioned in the slits in the plate, a certain deformation of the slit edges occurs, which can lie continuously against the outer skin of the pipe. If it is then provided that the deformations are provided with pinch folds, which each overlap the opposite cut edges, a stable positive connection is created in addition to the frictional connection between the tube and the slots. The new surface heat exchanger can be designed to be extremely stable and has excellent heat transfer properties.

It is advisable not to let the slots for inserting the pipe or coil pass through to the edge of the plate. In this case, at least the two connecting ends of the pipe are bent out at the level of the plate. The plate itself can therefore be kept stable because the slots for inserting the tube or the tube snake are only inside the plate surface so that it can keep a stiff peripheral edge.

It can be advantageous if the tube is formed in a serpentine shape with straight legs extending parallel to one another, to keep only these legs in parallel slots within the plate, while - in addition to the connection ends - the connecting bends of these legs also protrude cranked out of the plane of the plate and onto just rest on the plate. It has been shown that the resulting loss of heat-transfer contact surfaces is not so critical that the simplifications in production could not outweigh this. Above all, it is very simple in this embodiment to provide the pinch folds in the area of the parallel slots continuously on both sides of the plate, so that the tube in the area of its parallel legs not only on the end faces of the slot edges, but also on the pinch folds on the the edge areas of the plate adjoining the slot, so that the heat transfer area is thereby significantly increased.

In another embodiment, the slots can be interrupted by transverse webs which are deformed semicircular when the tubes are inserted, or even beforehand, the tube then being provided with the pinch folds only on the side of the plate opposite the transverse webs. Such a configuration can also be provided, for example, in the region of the connecting bends of the serpentine tube, so that it is not necessary to lead the connecting bends out of the plate plane in a cranked manner. Nevertheless, in this way, in the area of the connecting bends, there is no need to provide a pinch fold arrangement running on both sides, the manufacture of which is possible, but is not necessarily expedient in view of a later bending of the plate for adaptation to installation conditions.

In a third embodiment, finally, the deformations can be applied along the tube only at points at intervals in succession, with adjacent deformations also being arranged alternately on one or the other side of the tube protruding from the plate plane. This embodiment has the advantage, d ₃ B, the fastening of the pipe can take place in this manner largely independent of tolerances in the slot, and even in the region of the connecting arcs serpentine bent tubes. With this type of deformation of a tube in the form of a snake, the slot can therefore also have a shape adapted to this snake shape.

For the production of the new surface heat exchanger, a device according to subclaims 10 to 12 has proven to be particularly advantageous, with devices according to these features first of all positioning the pipe coil in the carrier plate and then also fastening it in a form-fitting manner.

• Fig. 1 die schematische Draufsicht auf einen Flächenwärmetauscher gemäß der Erfindung mit einem Rohr in Schlangenform,
• Fig. 2 den Teilschnitt durch den Flächenwärmetauscher der Fig. 1 längs der Linie II-II in vergrößertem Maßstab,
• Fig. 3 den Teilschnitt durch die Fig. 1 längs der Linie III-III, ebenfalls in vergrößertem Maßstab,
• Fig. 4 die Teildraufsicht auf einen Flächenwärmetauscher gemäß der Erfindung, bei dem die Schlitze zum Einsetzen der Rohrschlangenteile durch Querstege unterteilt sind,
• Fig. 5 den Teilschnitt durch den Wärmetauscher der Fig. 4 längs der Linie V-V,
• Fig. 6 die Draufsicht auf einen Flächenwärmetauscher ähnlich der Fig. 1, jedoch mit einer nur punktweise in Schlitzen der Platte befestigten Rohrschlange,
• Fig. 7 den Schnitt durch den Flächenwärmetauscher der Fig. 6 längs der Linie VII-VII,
• Fig. 8 den Teilschnitt durch den Flächenwärmetauscher der Fig. 6 längs der Linie VIII-VIII,
• Fig. 9 eine schematische Darstellung einer Vorrichtung zur Herstellung eines Flächenwärmetauschers gemäß Fig. 6,
• Fig. 10 die schematische Stirnansicht des bei der Vorrichtung der Fig. 9 verwendbaren Verformungsstempels,
• Fig. 11 eine Stirnansicht gemäß Fig. 10, jedoch von einem Verformungsstempel mit einem anders ausgebildeten Stirnende,
• Fig. 12 die Ansicht einer Verformungsstelle des Rohres des Flächenwärmetauschers der Fig. 6 in Richtung des Pfeiles XII der Fig. 8 gesehen, die bei Verwendung des Verformungsstempels der Fig. 10 entstanden ist und
• Fig. 13 die Ansicht gemäß Fig. 12 einer Verformungsstelle eines Rohres, die jedoch unter Verwendung eines Verformungsstempels mit der Stirnseite der Fig. 11 hergestellt wurde.

In the drawing, the invention is illustrated using exemplary embodiments and explained in the following. Show it:

• 1 is a schematic plan view of a surface heat exchanger according to the invention with a tube in the form of a snake,
• 2 shows the partial section through the surface heat exchanger of FIG. 1 along the line II-II on an enlarged scale,
• 3 shows the partial section through FIG. 1 along the line III-III, also on an enlarged scale,
• 4 shows the partial top view of a surface heat exchanger according to the invention, in which the slots for inserting the pipe coil parts are divided by transverse webs,
• 5 shows the partial section through the heat exchanger of FIG. 4 along the line VV,
• 6 is a top view of a surface heat exchanger similar to FIG. 1, but with a pipe coil which is fastened only at certain points in the plate slots,
• 7 shows the section through the surface heat exchanger of FIG. 6 along the line VII-VII,
• 8 shows the partial section through the surface heat exchanger of FIG. 6 along the line VIII-VIII,
• 9 shows a schematic illustration of a device for producing a surface heat exchanger according to FIG. 6,
• 10 shows the schematic end view of the deformation die that can be used in the device of FIG. 9,
• 11 is an end view according to FIG. 10, but of a deformation die with a differently designed end,
• Fig. 12 seen the view of a deformation point of the tube of the surface heat exchanger of Fig. 6 in the direction of arrow XII of Fig. 8, which was formed when using the deformation stamp of Fig. 10 and
• FIG. 13 shows the view according to FIG. 12 of a deformation point of a tube, which, however, was produced using a deformation stamp with the end face of FIG. 11.

In Fig. 1 are four, for example made of aluminum, four parallel to each other Slots 3, 4, 5 and 6 are arranged, each of which does not go to the edge la of the plate. In the embodiment shown, the slots 3 and 6 are formed somewhat longer than the slots 4 and 5. The slots 3 and 6 each run on their left side up to the dashed line 20, from which the slots 4 and 5 also extend. On their right side, however, the slots 3 and 6 extend up to approximately the boundary line 22, while the slots 4 and 5 only extend up to the indicated boundary line 21.

In these parallel to each other slots 3, 4, 5 and 6, the straight legs 2 ', 2 ", 2"' and 2 "" of a tube 2 bent in a snake shape are inserted so that the tube 2 each at diametrically opposite points its diameter is held between the opposing slot edges 8. The two open connection ends 2b, 2c are bent out of the plane of the plate 1, as shown in Fig. 3 with reference to one of the connection ends 2b Arch area can be problematic, but this is regarded as an exception, so the connecting arches 2d between the legs 2 ', 211 or 2' '' and 2 '' '' can be led out of the plate plane.

The width b of the slots 3, 4, 5 and 6 is chosen to be somewhat smaller in the exemplary embodiment shown than the diameter d of the tube 2, which is only indicated in FIG. 7, so that, as can be seen from FIG. 2, the tube 2, that has received an oval shape before the pressing in of its straight legs into the slots 3, 4, 5 and 6, which is denoted by 2e in FIG. 2, is pressed into the slots and with its widest point lies firmly against the opposite slot edges 8 . The tube 2 is also in contact with these slot edges, which enables good heat transfer between the heat exchange medium which is later passed through the tube 2 and the adjacent plate 1. 2, runs the axis of the tube 2 in its position 2e in the central plane of the plate 1. In the following it is spoken for this arrangement that the tube lies in the plate plane.

As can also be seen from FIG. 2, the position 2e of the tube 2 is not the final shape for the form-fitting attachment of the tube 2 in the slots in the plate. Rather, in the exemplary embodiment, the pipe legs 2 ', 2' ', 2' 'and 2' '' 'are continuously provided with deformation 7 from both sides of the plate, which in each case lead to continuous flattening on both sides of the pipe, in the region of the slot edges 8 but produce pinch folds 9 which grip the slot edges 8 from both sides in a form-fitting manner. The tube thus squeezed therefore sits positively and firmly in the plate 1. The contact surfaces between plate 1 and tube 2 are due to the pinch folds 9 and their contact surfaces on the plate 1 much larger than the end faces of the slot edges 8, so that excellent heat transfer is possible even during operation. Of course, it would also be possible to squeeze only the straight and parallel pipe legs because this is easier to manufacture Fig. 1 shown surface heat exchanger, the pipe legs 2 ', 2' ', 2' '' and 2 "" in the plate plane lie, the connecting bends 2d are either up or down out of this plate level, so that they are either on the side of the connection ends 2b, 2c or on the opposite side of the plate 1.

4 and 5, a modified embodiment of a surface heat exchanger is shown, insofar as here, which is also possible in principle in the embodiment of FIG. 1, a single continuous slot adapted to the snake shape of the tube 2 is provided, which consists of the straight sections 3 ', 4' and the arcuate connecting these two slit parts 23. This is in this continuous slot serpentine bent tube 2, with the exception of its connecting ends 2b, which protrude from the plate plane to the outside, similar to FIG. 3, inserted so that the pipe coil lies in the plate plane. In the embodiment of FIG. 4, the securing of the tube 2 in this position is carried out by transverse webs 10 which divide the slots 3 ', 23 and 4' and which are deformed semicircularly downwards before or when the tube 2 is inserted. The deformation can also take place in such a way that the tube 2 reaches the region of the crosspieces 10 with a little more than half of its circumference, so that it is held firmly in this position due to the deformation occurring when it is inserted. The top of the tube 2 can again be provided with deformations 7 in the form of a continuous flattening, so that the pinch folds 9 form, which rest on the plate 1 from the top. In addition, it is possible to fix the pipe bends 2d on the side facing away from the transverse webs 10 in that clamping tabs 24 are punched out of the plate 1 and partially placed over the circumference of the pipe in the region of the connecting bend 2d. A similar fixation is also conceivable for the connection ends 2b.

Another and extremely advantageous variant of a surface heat exchanger is shown in FIGS. 6 to 8. Here, as in FIG. 4, the serpentine slot arranged within the plate 1 corresponds to the serpentine shape of the tube 2. In this case, too, the slot is arranged exclusively within the plate and a peripheral edge la remains. The connection ends 2b and 2c are also led out of the plate level in this embodiment, as shown in Fig. 3. The connection ends 2b and 2c are secured here in the region of the edge la of the plate by riveted tabs 19. With the exception of its connecting ends 2b and 2c, the pipe 2, which otherwise runs completely in the plate plane, is not provided with continuous squeezes over the entire pipe length in this exemplary embodiment, but only with punctiform provided Squeezes 7a, which, as can be seen in detail from FIGS. 7 and 8, are each arranged along the tube 2 at a distance from one another and are designed such that adjacent squeeze points 7a with the squeeze folds 9 resulting therefrom each come from opposite sides of the plate 1 be provided on the tube 2, which is thus provided in its interior with alternating constrictions in the free cross section. These alternating constrictions act on the flowing heat exchange medium in the manner of flow baffles, which excite the flowing medium to turbulence and therefore ensure the improvement of the heat transfer coefficient. The alternate squeezing through the squeezing points 7a is sufficient to bring about a secure fastening of the tube 2 over its entire length in the plate plane. It is advantageous that 2d pinch points are also provided in the area of the connecting bends. The intimate contacting of the tube outer walls with the slot edges 8, which is also present in the area of the tube sheets 2d, ensures sufficient heat transfer between the tube and the plate 1.

9 to 11 a device for producing a surface heat exchanger according to FIGS. 6 to 8 is shown schematically. The device consists of two mutually movable blocks 13 and 14, between which the plate 1, previously provided with the punched-out slots, is inserted with the serpentine tube 2. The serpentine tube 2 has not yet been brought into the position shown in FIG. 9. The serpentine tube 2 is initially when the blocks 13 and 14 have moved apart above the plate level and only protrudes with a part of its respective circumference into the punched slots. The blocks 13 and 14 each have recesses 15 at the location of the slots or at the location where the tubes 2 are pressed into the slots, which correspond to the course of the pipe coil and the course of the slots and have a cross section that is approximately corresponds to half the contour of the tube 2 to be used. In the exemplary embodiment shown, the recesses 15 therefore have a semicircular cross section. If the blocks 13 and 14 are therefore moved together until they abut the sheet metal 1, the round tube 2 is simultaneously pushed into the plate plane and, similarly as already described with reference to FIG. 1, between the diametrically opposite slot edges 8 jammed at its widest point.

In blocks 13 and 14, holes 25 with punches 12 guided therein are provided along the recesses 15 at a corresponding distance, which can be acted upon from outside with a force in a manner not shown and can be pressed in the direction of tube 2. Such stamps 12, as shown, are provided both in the upper block 13, and - in a manner not shown - in the lower block 14, so that by pressing these stamps 12, as can be seen from FIGS. 6 to 8, punctiform Squeezes 7a can alternately be attached to the tube 2 on both sides. Depending on the shape of the end face 26 of the stamp 12, the pinch points 7a are given different shapes. If, for example, a stamp 12 'with an end face 27 according to FIG. 10 is used, which is approximately rectangular in shape and merges backwards into the cylindrical part 29 through inclined surfaces 28, then pinch points 7a arise on the two tube sides, which roughly correspond to the appearance Fig. 12. If, however, a stamp 12 ″ is provided with a circular end face 30 which runs perpendicular to the cylindrical part 29, then pinch points 7a are formed which, viewed perpendicularly to the plate plane, have the appearance according to FIG. 13. The pinch points 7a according to FIG. 13 result in longer pinch folds 9 ¹¹ which can overlap the plate than in the example of FIG. 12, where the pinch folds 9 'remain relatively short. However, the squeezing forces to be applied are lower in the example of FIG. 12. Here, the distance between the alternating pinch points may be smaller than in the example Fig. 13 can be selected if the heat transfer surface between the tube and plate is to be kept as large as possible.

Instead of the type of fastening shown by pinching, a combination of such pinching and continuous pinching would of course also be possible, for example pinpointing in the area of the tube sheets and continuous pinching of the tube in the area of its straight legs.

Claims (13)

1. surface heat exchanger, consisting of a plate made of heat-conducting material and at least one tube connected to it, in particular in a meandering shape, through which a heat exchange medium can flow, characterized in that the plate (1) with slots (3, 4, 5, 6, 23) is provided, the width (b) of which is adapted to the diameter (d) of the tube (2), and that the tube is inserted into the slots approximately flush with the plate and by means of deformations transverse to its axis (2a) ( 7) is held positively on the slot edges (8). 2. Surface heat exchanger according to claim 1, characterized in that the width (b) of the slots (3, 4, 5, 6, 23) is slightly smaller than the diameter (d) of the tube (2). 3. Surface heat exchanger according to claims 1 and 2, characterized in that the deformations (7) are provided with pinch folds (9) which each overlap the opposite slot edges (8). 4. Surface heat exchanger according to claims 1 to 3, characterized in that the slots (3, 4, 5, 6) do not go to the edge (la) of the plate (1) and that the tube (2) at least with its two connection ends (2b, 2c) is cranked out of the plane of the plate (1). 5. surface heat exchanger according to claims 1 to 4, characterized in that the tube (2) is formed in a serpentine shape with parallel parallel straight legs (2 ', 2' ', 2 "', 2" ") and that only the legs in parallel slots (3, 4, 5, 6) are held, while the connecting bends (2d) are cranked out of the plane of the plate (1). 6. Surface heat exchanger according to claims 1 to 5, characterized in that the pinch folds (9) in the region of the slots (3, 4, 5, 6) are provided continuously on both sides of the plate (1). 7. Surface heat exchanger according to one of claims 1 to 4, characterized in that the slots (3) are interrupted by transverse webs (10) which are semicircularly deformed when the tubes (2) are inserted, and that the tube is only on the transverse webs ( 10) opposite side of the plate (1) is provided with pinch folds (9). 8. Surface heat exchanger according to one of claims 1 to 4, characterized in that the deformations (7) are attached point by point at intervals along the tube (2). 9. surface heat exchanger according to claim 8, characterized in that adjacent deformations (7) alternately on one or the other, from the plate plane projecting side of the tube (2) are arranged. 10. Surface heat exchanger according to claim 8 and 9, characterized in that the tube (2) is bent in a serpentine shape and a slot (3, 4, 5, 6, 23) adapted to the serpentine shape of the tube is provided, in which the tube bends (2d) are recorded approximately flush with the plate level. 11. A device for producing a surface heat exchanger according to claim 1, characterized by a holder (11) for the plate (1) and by at least one movable relative to the holder punch (12) for positioning and for deforming the tube (2). 12, Apparatus according to claim 11, characterized in that the holder consists of two opposite, movable blocks (13, 14), at least one of which is provided with a depression (15) which is adapted to the tubular shape and is opposite the stamp (12). 13. The apparatus according to claim 12, characterized in that each of the blocks (13, 14) is provided with the recesses (15) and that along these recesses and transversely movable in each of the blocks a plurality of punches (12) for deforming the tube point by point (2) are guided, of which the punches assigned to the opposite blocks are each offset from one another in the direction of the depressions.

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