WO2008071183A1 - Heat exchanger - Google Patents

Abstract

The invention relates to a heat exchanger in which finned panels (11) which are arranged in a stacked fashion have a plurality of fluid-conducting tubes extending through them and form fin-tube blocks, wherein the ends of the tubes are fastened to opposite tube plates and wherein the tube plates are connected to one another by means of side walls which extend parallel to the at least one fin/tube block. For vibration damping, the side walls (13) are in form-fitting engagement with the finned panels (11) directly or indirectly with the interposition of at least one form-fitting element (16) which extends in the longitudinal direction of the side walls (13).

Description

 heat exchangers

The invention relates to a heat exchanger having the features in the preamble of patent claim 1.

Finned tube heat exchangers are state of the art in a wide variety of designs. The heat exchange takes place between a liquid which flows through the finned tubes and a gas which flows around the tubes on the outside. About the ribs, the heat exchanger surface is greatly increased and the heat transfer intensified. The fluid-carrying tubes are fixed in tubesheets, so that the liquid medium, starting from so-called water chambers, can flow into several tubes at the same time.

It is known to form finned tube packages in which a plurality of fluid-carrying tubes pass through stacked finned plates together. The fixation of the ribs on the tubes, for example, by expanding the tubes, so that they are pressed against the openings in the finned tube packages. In this way can be provided in a very compact design heat exchanger with large surfaces for a variety of applications. The tubes can also be soldered to the ribbed plates. Usually, the opposing tube sheets are connected to one another via side walls connected, which are also required for air flow. In order to give greater stability to the entire arrangement, the side walls can be connected to one another by means of cross members, which run transversely to the pipe direction and extend in a manner that is parallel to the tube sheets.

The vibration excitation of the heat exchanger results from the coupling of the heat exchanger with vibrating systems. Especially in connection with generators or in general in connections with electrical systems often results in a vibration excitation of 50 hertz or 60 hertz. Depending on the dimensions of the heat exchanger, this vibration excitation may coincide with natural frequencies of the heat exchanger, resulting in resonant vibrations. These vibrations can lead relatively quickly to the destruction of the tubes and thus the destruction of the entire heat exchanger by leakage at the plurality of joints between the pipes and the ribs.

Efforts have therefore already been made to dampen the vibrations in that cross members press the individual finned tube packages firmly against one another. In addition, a damping element, such as a damping layer made of an elastomer, can be incorporated between the cross members and the rib plates. In addition, in the support region between the cross member and the fin sheets, heat resistant silicone or other elastic material may be introduced into the rib gaps to enhance the support between the fin sheets and the cross member.

Instead of cross beams, which press the finned tube packages from the outside against each other, an intermediate plate can be introduced into the finned tube package. The intermediate plate is virtually a very thick-walled ribbed plate, which, unlike the usually very thin-walled ribbed plates, can be screwed directly to the side walls. This results in a direct support of the pipes and not just one indirect support of the pipes via cross beams, which are pressed together by incorporation of heat-resistant silicone liners.

Nevertheless, it has been shown in practice that destructive oscillations occur at heat exchangers, in particular when the heat exchanger is used in connection with internal combustion engines, since the spectrum of the excitation frequencies due to the different rotational speeds and due to rotational speed fluctuations is substantially greater here. In addition, the mounting of the cross member requires special design measures in the side walls, as they should provide a defined contact force in the support area. The use of intermediate plates between the rib plates is structurally complex, since the intermediate plates must have a variety of holes that are much more expensive to produce in thick-walled intermediate plates due to the required close tolerances than thin-walled fin plates.

On this basis, the invention is based on the object to show a vibration control support for finned tube heat exchanger, which allows improved support of the finned tube packages and at the same time is easy and inexpensive to implement.

This object is achieved with a heat exchanger having the features of patent claim 1.

Advantageous developments of the inventive concept are the subject of the dependent claims.

The heat exchanger according to the invention is a so-called finned tube heat exchanger, in which stacked arranged fin plates of several fluid-carrying tubes are interspersed and form so-called finned tube packages. The ends of the tubes are fixed in a known manner to the opposite tube sheets, being between the Tube bottoms extend sidewalls. Overall, the heat exchanger thereby obtains a rectangular configuration.

Decisive in the heat exchanger according to the invention is that the side walls are in direct or indirect inclusion of at least one in the longitudinal direction of the side walls ersteckenden positive-locking element in positive engagement with the rib plates. The fact that the entire side walls or arranged on the side walls form-fitting elements can be used to support the finned tube packages, results in a much larger support area than he could be realized with cross members and consuming manufactured intermediate plates. In addition, a lateral support in the area of the side walls, unlike large overhead cross beams, does not affect the flow cross-section.

Of course, it is possible to arrange additional cross member to stabilize the side walls against each other. However, it is sufficient to form the cross members as tie rods or tie rods to give the entire heat exchanger a higher rigidity. In addition, the crossbeam no longer has to have a specific minimum cross-sectional area, which hitherto has resulted from the maximum permissible lateral surface pressure of the finned tube packages.

The fact that now stands by the support of the finned tube packages a high number of fin plates and in particular each fin plate of the heat exchanger in indirect or direct positive engagement with the side walls, there is an excellent support, since the free-swinging length of the finned tube, unlike punctual support , has been reduced to the value zero. This changes the natural frequency of the entire heat exchanger. In this way it is possible to set the natural frequency of the respective finned tube system so that it does not lie in the range of the exciter vibrations to be expected at the upstream drive machines. In the transferring sense, the individual ribbed plates in the context of the invention assume the function of previously used cross members or intermediate plates, so that the freely oscillating length of a finned tube package is essentially limited to the distance between two ribbed plates. However, such small distances and the associated natural frequencies are outside the excitation range of today's drive machines, so that the risk of vibration-induced damage of such configured heat exchanger is greatly reduced.

The positive engagement with the fin sheet may be via grooves and springs formed in the side walls or in the side walls facing rib outer edges, i. via projections pointing in the direction of the finned tube package, which projections run parallel to the tubes and rise away from the usually flat side wall. Preferably, the grooves are located in the rib outer edges and the springs on the positive-locking element or directly on the side wall. The use of a positive-locking element has the advantage that specially configured extruded profiles for the form-fitting support of the finned tube packages can be used cost-effectively combined with side walls in flat steel construction. In addition, the interlocking elements may consist of a vibration-damping material, such as plastic. Regardless of the choice of material, additional damping layers in the form of elastomeric materials can be arranged between the side walls and the positive connection and the rib outer edges or between the form-fitting element and the rib outer edges. In principle, it is also conceivable that the damping element is formed by the positive-locking body itself.

The advantages of the support according to the invention come into play, in particular, when a recess, which anyway results from the manufacturing process, can be used in the rib outer edge as a groove. This is the case when the fluid-carrying tubes are arranged offset in each second row to the first row, so that at one edge Trim the pre-punched fin sheet always gives a groove that corresponds to a circle segment. It is regarded as optimal if the grooves in the outer edges of the ribs of prefabricated, perforated ribbed plates are semicircular in configuration and, due to the manufacturing process, have the same diameter as the remaining pre-punched holes penetrated by the tubes in the ribbed plates. Depending on the number of ribs of the rows of tubes are located in the rib outer edges at least one, but regularly a plurality of aligned grooves. In the mounting position in these grooves engages in a matched to the contour of the grooves spring or a suitably configured interlocking element.

However, it is also conceivable within the scope of the invention that the engagement does not take place at the end faces of the finned tube packages, i. takes place in the region of the rib outer edges, but that the finned tube packages are supported by their corners on the interlocking elements or the side walls. For this purpose, it is provided that the corners of the rib plates are bent by about 90 °, so that touching each other adjacent rib plates on the folded corner pieces and form a chamfer at each corner of the finned tube package, which is supported flat on support brackets of the side walls or a positive locking element. By folding the corners a corner surface is created, which is adapted to reach flat on a correspondingly inclined support bracket to the plant. In this way, a wedge-shaped bond between the finned tube package and the side walls or the form-locking element results. If the side wall rests firmly on the finned tube packages, they are centered on the side walls or form-fitting elements and thereby, as it were, wedged.

Between the support brackets, the outer edges of the ribs should extend at a distance from the form-fitting element or the side wall, so that the centering of the finned tube package can be ensured with respect to the side wall or opposite the positive-locking element. The particular advantage of this type of lateral fixation of the finned tube packages is the fact that a lateral delivery of the side walls or of the interlocking elements can be brought about to adjust the contact force of the side walls exactly to the respective requirements. For this purpose, the side walls can be connected to each other via adjustable in length tie rods. Of course, such tie rods can also be provided in tongue and groove arrangements to ensure the positive connection between the frame of the heat exchanger and the finned tube packages, even with strong vibration excitation.

The invention will be explained in more detail with reference to the dargestellen in the schematic drawings embodiments. Show it:

Figure 1 is a perspective view of a heat exchanger;

Figure 2 shows a heat exchanger in longitudinal section from the state of

Technology in a first embodiment;

FIG. 3 shows a longitudinal section through a prior art heat exchanger in a further embodiment;

Figure 4 in cross section a portion of a heat exchanger in a first embodiment;

Figure 5 in cross section a portion of a heat exchanger in a second embodiment and

Figure 6 is an end view of a finned tube bundle with folded corners.

FIG. 1 shows a heat exchanger 1 of known type. In this case, it is a charge air cooler. The heat exchanger 1 is configured rectangular and is traversed in the direction of the arrow L of air. Air flows between a plurality of fin sheets 2 connected to pipes 3. The tubes are flowed through by a fluid. At a Charge air cooler, the fluid is cooler than the air, so that the air flow cools and heats the fluid.

The individual tubes 3 are each set with their ends in a tube plate 5. Between the tube sheets 5 is formed by the fin sheets 2 and the tubes 3 finned tube package 4. Parallel to the finned tube 4 extend side walls 6, 7, which are bolted to the tube sheets 5.

Heat exchangers of this type can be additionally provided with massive cross members for vibration damping, as shown in Figure 2. FIG. 2 shows a longitudinal section through a heat exchanger. The tubes 3 ¹ run in the image plane from left to right. The individual rib plates 2 ¹ extend in the image plane from top to bottom. It can be seen that in this heat exchanger two finned tube packages 4 'are arranged one above the other. Between the finned tube packages 4 'is a massive center support 8, which rests directly on the finned plates 2' of the finned tube packages 4 '. The counterpart to the central support 8 are cross members 9, which are arranged above and below the finned tube packages 4 ¹ and are screwed to the side walls 6, 7. In this way a vibration in this support area is prevented. For damping can be arranged between the cross member 9 and the fin sheets 2 'fillings of heat-resistant silicone. In this type of support, the tubes 3 ¹ indirectly via the ribs 2 ¹ and not shown in detail silicone supported.

As an alternative, it is known to provide 9 intermediate plates 10 instead of the cross member, which extend parallel to the rib plates 2 'and are immediately penetrated by the tubes 3 ¹ . Also in this way is a support of the finned tube packages 4 'by multiple connection of the intermediate plate 10 of the side wall 6, not shown, possible (Figure 3). FIGS. 4 and 5 show details of heat exchangers according to the invention of two different embodiments. In Figure 4, an edge region of a ribbed plate 11 is shown in plan view, the holes 12 are penetrated by the fluid-carrying pipes, not shown. It can be seen that the ribbed plate 11 is in the installed position with a side wall 13 in a form-fitting engagement. For this purpose, a semicircular groove 15 is formed in the side wall 13 facing rib outer edge 14, in which engages an equally semicircular spring 16 of the side wall 13. The spring 16 preferably extends over the entire length of the side wall 13 and is therefore in positive engagement with all the rib plates 11.

Particularly useful in this embodiment is that the pre-punched with the holes 12 fin plate 11 is cut in the region of a centrally located hole 12, so that the semicircular groove 15 is formed from a hole. It is therefore not necessary for the production of the groove 15, a separate step, but can be used on previous manufacturing steps.

Of course, it would also be possible to let the cutting edge of the fin plate 11 along the line S, so that two holes 12 are formed as grooves. Accordingly, two springs 16 would have to be present on the side wall 13. Regardless of whether one or more grooves or springs are provided on the rib outer edges 14, in the embodiment of Figure 4 and modified therefrom embodiments is a form-fitting composite, in which a component of the side wall 13 is encompassed.

The embodiment of FIG. 5 differs from that of FIG. 4 in principle in that it does not encompass the side wall 17 illustrated there, but rather the ribbed plate 11 a. In order to provide a sufficient contact surface of the rib plates 11a on the side wall 17, the corners of the rib plates 11a are bent by approximately 90 °, so that adjacent rib plates 11a, 11b on the folded corner pieces 18th touch and form chamfers 19, which are supported in the installed position surface on support brackets 20 of the side walls 17. Figure 6 shows a schematic representation of the corner pieces 18 of the individual fin sheets 11a, 11b, which overlap and therefore form the desired chamfer 19. On the representation of the tubes and any exhibitions of the individual ribs 11a, 11b has been omitted in Figure 6.

The components designated as side wall 13, 17 in FIGS. 4 and 5 could also be positive-locking elements which are arranged as separate components between the side wall and the ribbed plates 11, 11a. The interlocking elements may be made of a vibration damping material, such as e.g. Plastic, be made. The integration of elastomeric intermediate layers between the side wall 13, 17 and the positive-locking element and the fin plates 11, 11a is conceivable.

In addition, it is conceivable that for very wide finned tube packages additional partitions may be provided which extend parallel to the side walls. In this case, provide the intermediate walls for additional support. Such partitions may also be provided on both sides with corresponding form-fitting elements, such as springs or support brackets, as shown by way of example in Figures 4 and 5. In this way, the vibration damping in very wide-building coolers with multiple juxtaposed finned tube packages can be ensured.

REFERENCE CHARACTERS:

1 - heat exchanger

2 - ribbed plate 2 ¹ - ribbed plate 3- tube

3 ¹ - pipe

4 - finned tube package 4 ¹ - finned tube package

5 - tube bottom

6 - side wall

7- side wall

8- Center support 9 - Cross member

10 - intermediate sheet

11 - ribbed plate 11a ribbed plate 11b ribbed plate

12 hole

13 - side wall

14- rib outer edge

15 groove

16 spring

17 - side wall

18- corner piece

19- bevel

20- support console

L-arrow

S- cut edge

Claims

claims 1. Heat exchanger, in which stacked arranged fin sheets (2, 11, 11 a, 11 b) of several fluid-carrying tubes (3) are interspersed and finned tube packages (4), wherein the ends of the tubes (3) attached to opposite tube sheets (5) are and wherein the tube sheets (5) parallel to the at least one finned tube package (4) extending side walls (6, 7, 13, 17) are interconnected, characterized in that the side walls (6, 7, 13, 17) directly or indirectly with the inclusion of at least one in the longitudinal direction of the side walls (6, 7, 13, 17) extending positive locking element in positive connection with the rib plates (2, 11, 11a, 11b) are. 2. Heat exchanger according to claim 1, characterized in that on the side walls (13) facing rib outer edges (14) grooves (15) are formed, in which springs (16) of the side walls (13) or a positive locking element engage. 3. Heat exchanger according to claim 1 or 2, characterized in that between the side walls (6, 7, 13, 17) and the fin sheets (2, 11, 11 a, 11 b) is arranged a damping element. 4. Heat exchanger according to claim 3, characterized in that the damping element is formed by the form-fitting body. 5. Heat exchanger according to one of claims 1 to 4, characterized in that each ribbed plate (2, 11, 11 a, 11 b) in indirect or direct positive engagement with the side walls (6, 7, 13, 17). 6. Heat exchanger according to one of claims 1 to 5, characterized in that the grooves (15) in the rib outer edges (14) are configured semicircular and have the same diameter as the other pre-punched and of the tubes (3) passing through holes (12) in the fin sheets (11, 11 a). 7. Heat exchanger according to one of claims 1 to 5, characterized in that the corners of the rib plates (11 a, 11 b) are bent so that adjacent fin plates (11 a, 11 b) on the folded corner pieces (18) touch and bevels ( 19), which are supported flat on support brackets (20) of the side walls (17) or a positive locking element. 8. Heat exchanger according to claim 7, characterized in that the side walls (6, 7, 13, 17) are connected to each other via adjustable in length tie rods.