This application claims the benefit of priority under 35 U.S.C. ยง119 of German Patent Application DE 10 2011 003 609.1 filed Feb. 3, 2011, the entire contents of which are incorporated herein by reference.
The present invention relates to a finned-tube heat transfer device, in particular for vehicle applications. The present invention additionally relates to a process using such a finned-tube heat transfer device.
Finned-tube heat transfer devices are characterized by a multitude of parallel tubes which are provided with fins, wherein the fins and the tubes are exposed to and externally circulated by a first fluid and the tubes are subjected to a second fluid through-flow.
In detail, such a finned-tube heat transfer device can comprise a housing enclosing a first flow path for a first fluid and which comprises a first inlet for the first fluid as well as first outlet for the first fluid. Furthermore, such a finned-tube heat transfer device typically comprises a tube system forming a second flow path for a second fluid, which comprises a second inlet for the second fluid and a second outlet for the second fluid and which in the housing is coupled to the first flow path in a heat-transferring manner. The tube system now comprises a multitude of tubes which are parallel to one another, which extend between two housing walls laterally delimiting the first flow path and which are provided with fins within the first flow path. The tubes are fluidically interconnected outside the first flow path.
In order to fluidically interconnect the tubes outside the first flow path it is possible in principle to pass the tubes through the mentioned housing walls and connect these on an outside facing away from the first flow path using U-shaped connecting pieces. Such a design is comparatively expensive to produce. Apart from this, the design freedom is restricted since the U-shaped connecting pieces regularly produced through bending forming have to adhere to a minimum bending radius for stability reasons.
The present invention deals with the problem of providing an improved embodiment for a finned-tube heat transfer device of the type mentioned at the outset, which is more preferably characterized in that it can be produced comparatively easily and/or has an improved design freedom.
According to the invention, a finned-tube heat transfer device, more preferably for vehicle applications, is provided with a housing enclosing a first flow path in the circumferential direction with the first flow path penetrating the housing in the longitudinal direction of the housing. The housing at its longitudinal ends comprises a first inlet for the first fluid and a first outlet for the first fluid. A tube system forms a second flow path for a second fluid, which comprises a second inlet for the second fluid and a second outlet for the second fluid and which is arranged in the first flow path and is coupled in the housing to the first flow path in a heat transferring manner. The tube system comprises a multitude of tubes which are parallel to one another, which extend between two housing walls laterally delimiting the first flow path and which within the first flow path are provided with fins. The tubes are fluidically interconnected outside the first flow path. The fluidic connection of the tubes is effected within the two housing walls.
The invention is based on the general idea of fluidically interconnecting the tubes within the two housing walls. Through the integration of the fluidic connections in the two housing walls, a multitude of individual, separate connecting pieces can be omitted, which reduces the assembly costs. In addition, advantages with regard to the design freedom are achieved, since no bending radii of connecting pieces have to be considered. In particular, the finned-tube heat transfer device according to the invention is suitable for a cost-effective series production, for example for vehicle applications. Particularly advantageously, the invention can be realized with a finned tube heat transfer device, with which the first flow path penetrates the housing in a longitudinal direction of the housing and with which the first flow path is enclosed by walls of the housing in the circumferential direction of the housing, quasi tunnel-like. A first inlet of the first flow path and a first outlet of the first flow path in this case are formed on longitudinal ends of the housing. The second flow path is in this case arranged with its tubes and its fins in the first flow path and accordingly circulated by (and in heat transfer contact with) the first fluid. The two housing walls, in which the tubes are fluidically interconnected, are located opposite each other on the first flow path and can in particular be interconnected at their lateral margins via two further housing walls, which are likewise located opposite each other on the first flow path.
According to an advantageous embodiment, the two housing walls can contain hollow spaces, which are fluidically connected with the respective tubes. The hollow spaces then realise the fluidic connection of those tubes, which are connected to the respective hollow space.
An embodiment that can be realized particularly cost-effectively is characterized in that the respective housing wall is of a double-walled design and comprises an inner wall facing the first flow path and an outer wall facing away from the first flow path. The fluidic connection of the tubes is then effected between inner wall and outer wall, i.e. within the double-walled housing wall, which can also be called double wall in the following.
Practically, the tubes can penetrate the respective inner wall and bend in hollow spaces, which are formed between inner wall and outer wall. Such an embodiment can be produced particularly easily and cost-effectively. For example, the tubes can penetrate the inner wall in conventional manner and be tightly fastened to said inner wall. Instead of assembling a multitude of separate connecting pieces, the respective outer wall can in this case be simply assembled to the inner wall in order to form all required fluidic connections in a single operation.
Practically, the hollow spaces which are formed between inner wall and outer wall can be exclusively formed in the outer wall, for example through deep-drawing or stamping. The hollow spaces formed in the outer wall are closed through the inner wall in the assembled state, which in contrast to the outer wall can be preferentially configured flat.
The hollow spaces are formed in the respective outer wall in the form of depressions which are open towards the inner wall. In the assembled state, however, the inner wall closes off the depressions, as a result of which the hollow spaces are formed within the double-walled housing wall. The depressions can be produced in the outer wall for example through stamping, through deep-drawing, through pressing, in particular through extruding, through spin-forming or through any other suitable forming process. In addition to these forming processes, which can be realized comparatively cost-effectively, cutting methods or casting methods are also conceivable in principle, which, however, are unsuitable for series production because of the higher costs.
According to an advantageous embodiment, the hollow spaces can form connecting channels each of which connect an exit end of a single tube with an entry end of a single other tube. These connecting channels then represent individual connecting pieces, each of which interconnect exactly two tubes. This can be advantageous for certain configurations for finned-tube heat transfer devices.
It is likewise possible, alternatively, to configure the hollow spaces so that they form connecting chambers, each of which connect the exit ends of a plurality of tubes to the entry ends of a plurality of other tubes. Within such connecting chambers, a homogenization with respect to the temperature within the second fluid can take place, which can be advantageous with certain applications of such finned-tube heat transfer devices.
With another embodiment, the outer wall can bear against the inner wall in a flat manner or be fastened to said inner wall in a flat manner. For example, outer wall and inner wall can be soldered to each other or welded to each other. Alternatively, the outer wall can be flat in contact with or fastened to the inner wall in a line-shaped manner. Particularly suited for this is a welded connection, with which a line-shaped weld seam can be particularly easily realized. Flat contacting can also be combined with a line-shaped fastening.
Practically, the respective inner tube can have tube openings each of which are penetrated by a single tube. Thus, each individual tube has to be ultimately fastened to the inner wall. In particular, the tube openings can each be designed with a circumferential collar or without collar. Similarly, the tube openings can each be designed as passage. The collarless configuration can be realized particularly cost-effectively. An embodiment with circumferential collar on the respective tube opening or with a passage on the respective tube opening simplifies the manufacture of a welded connection or a soldered connection between the respective inserted tube and the inner wall.
While each of the tubes are fastened to the respective inner wall, in particular welded or soldered, it can be provided according to an advantageous embodiment that the tubes do not touch the respective outer wall. This simplifies realizing the hollow spaces between the inner wall and the outer wall.
For finning the tubes there are different possibilities, each of which can be advantageous depending on the application of the finned-tube heat transfer device. For example, each tube can have its own fins within the first flow path. Alternatively it can be provided that a plurality of tubes has common fins within the first flow path. Furthermore, it is likewise possible that all tubes within the first flow path have common fins. The use of common fins leads to a particularly intensive stiffening of the tube system within the first flow path.
Insofar as all tubes are assigned common fins, these fins can run parallel and/or congruent with the two housing walls in the manner of lamellae. This produces an effective and low-resistance flow guidance for the first fluid in the first flow path.
According to another advantageous embodiment, the second fluid inlet, via which the second fluid enters the tube system, can be formed on one of the two housing walls so that the second fluid inlet is located outside the first flow path and is comparatively easily accessible. Here it can be more preferably provided that the respective housing wall comprises a hollow space designed as distribution chamber, which fluidically connects the entry ends of a plurality of tubes to the second fluid inlet.
In addition or alternatively, the second fluid outlet, through which the second fluid exits the tube system, can be formed on one of the two housing walls and, accordingly, be arranged outside the first fluid path and, accordingly, be easily accessible. In this case, too, it can be practically provided that the respective housing wall comprises a hollow space designed as collecting chamber, which fluidically connects the exit ends of a plurality of tubes to the second fluid outlet.
According to another practical embodiment, the tubes are arranged next to one another in lines running transversely to the flow direction of the first fluid. Practically, the tubes can in this case be aligned in lines, which follow in succession in the flow direction of the first fluid or be arranged offset to one another transversely to the flow direction of the first fluid. While the aligned arrangement offers a reduced flow resistance, the offset arrangement leads to an improved heat transfer.
The tubes can have a circular cross section or an oval cross section or an elliptical cross section. In principle, other cross-sectional geometries are also conceivable, which have shapes other than round. An advantageous embodiment results with the tubes extending transversely to the longitudinal direction of the housing through the first flow path and being arranged parallel next to one another both in the longitudinal direction as well as the transverse direction of the housing. This produces a particularly compact design, which can transfer a lot of heat in a small space.
Additionally or alternative it can be provided that the fluidic connections of the tubes are realized such that a plurality of tube groups connected in parallel are formed, each of which comprises a plurality of tubes connected in series. In this way, relatively large flow rates with comparatively little flow resistance can be realized in the second flow path despite comparatively small flow cross sections of the individual tubes.
Particularly advantageously, the finned-tube heat transfer device introduced In this case can be employed as exhaust gas heat transfer device or as evaporator or as exhaust gas recirculation cooler or as charge air cooler or as heater heat transfer device or as evaporator or condenser of an air-conditioning device or as evaporator or condenser of a waste heat utilization device based on a Rankine cycle process, each more preferably in a motor vehicle.
Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the associated Figure description by means of the drawings.
It is to be understood that the features mentioned above and still to be explained in the following cannot only be used in the respective combination stated, but also in other combinations or by themselves without leaving the scope of the present invention.
Preferred exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description, wherein same reference characters refer to same or similar or functionally same components. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
In the drawings:
Referring to the drawings in particular, according to
The finned-tube heat transfer device 1 additionally comprises a tube system 9, which forms a second flow path 10 likewise indicated by arrows for a second fluid, which is preferentially liquid. The tube system 9 comprises a second inlet 11 for the second fluid and a second outlet 12 for the second fluid. The tube system 9 is coupled to the first flow paths 3 in a heat transferring manner in the interior of the housing 2.
The tube system 9 comprises a multitude of tubes 13, which run parallel to one another and in this case extend between the two housing walls 7. In this case, the tubes 13 extend perpendicularly to the planes of the housing walls 7 and perpendicularly to the flow direction 6 of the first fluid. Thus, the tubes 13 extend through the first flow paths 3 so that they are exposed to or circulated by the first fluid 3. In order to improve the heat transfer between first fluid and second fluid, the tubes 13 are provided with fins 14 within the first flow path 3.
For realizing the second flow path 10, the tubes 13 are fluidically interconnected in a suitable manner. This fluidic connection of the tube 13 in this case is effected outside the first flow path 3, namely within the two housing walls 7. To this end, hollow spaces 15 are provided in the housing walls 7, which are fluidically connected to the tubes 13.
According to the
Practically, the hollow spaces 15 are produced in that depressions 18 are formed in the outer wall 17, which are open towards the inner wall 16 and which in the assembled state of the housing wall 7 are closed off by the inner wall 16. For example, the depressions 18 are produced in the outer wall 17 through forming. Because of this, the outer wall 17 has a dent-like structure, wherein the outer wall 17 continues to extend in a plane. In contrast with this, the inner wall 16 is practically designed flat. According to the
The inner wall 16 has tube openings 20, through which the tubes 13 are passed. In this case, each tube 13 penetrates each tube opening 20. In the example of
According to
Alternatively to this,
Such distribution chambers 28 make possible a parallel interconnection of a plurality of tube groups, which in turn comprise a plurality of series-connected tubes 13 each. Because of this, the flow rate through the second flow path 10 can be increased.
According to
As is more preferably evident from the
According to
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
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10 2011 003 609 | Feb 2011 | DE | national |
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