Abstract
A heat exchanger and a method of manufacturing a heat exchanger having an internal conduit for conducting a fluid, and a heat dissipating body for dissipating heat of the fluid. The heat dissipating body has a cavity extending in a longitudinal direction. An end piece of the internal conduit extends inside of the cavity and has an orifice facing a bottom surface of the cavity for feeding the fluid into a bottom area of the cavity. An inner shell of the heat dissipating body includes a first portion and a second portion, each portion having at least two ribs transversally displaced in relation to each other. At least one rib of one of the first and the second portion is transversally displaced in relation to each rib of the other of the first and the second portion.
Claims
1. A heat exchanger comprising: an internal conduit for conducting a fluid; and a heat dissipating body for dissipating heat of the fluid, wherein the heat dissipating body includes a cavity extending in a longitudinal direction defined by the heat dissipating body, at least one end piece of the internal conduit extending inside of the cavity, the end piece having an orifice facing a bottom surface of the cavity, for feeding the fluid into a bottom area of the cavity; a streaming space extending in the longitudinal direction between an outer shell of the internal conduit and an inner shell of the heat dissipating body, said streaming space conducting the fluid away from the bottom surface; a first portion of the inner shell of the heat dissipating body including at least two ribs transversally displaced in relation to each other; and a second portion of the inner shell of the heat dissipating body adjacent to the first portion, said second portion including at least two ribs transversally displaced in relation to each other, at least one rib of the second portion being transversally displaced in relation to each rib of the first portion or at least one rib of the first portion being transversally displaced in relation to each rib of the second portion, wherein the heat dissipating body comprises: a cast or extruded first segment including the first portion, and a cast or extruded second segment including the second portion.
2. The heat exchanger according to claim 1, in which the first segment and the second segment are substantially identical.
3. The heat exchanger according to claim 1, wherein each rib of the first portion extends to a channel located between two adjacent ribs of the second portion.
4. The heat exchanger according to claim 1, including a channel located between any two adjacent ribs of the first portion, the channel extending to one rib of the second portion.
5. The heat exchanger according to claim 1, in which the heat dissipating body or at least the inner shell of the heat dissipating body defines a rotational symmetry axis.
6. The heat exchanger according to claim 5, wherein the first and the second portions each include N ribs, and wherein the position of an i.sup.th rib of the first portion includes an azimuthal angle of 360/N*i, wherein i=0, . . . , N1, and the position of each j.sup.th rib of the second portion includes an azimuthal angle of 360/N*(j+), wherein j=0, . . . , N1, and wherein a constant has a value between 0 and .
7. The heat exchanger according to claim 1, wherein the ribs of the first portion and the ribs of the second portion are elongate extending in the longitudinal direction.
8. The heat exchanger according to claim 1, wherein the ribs of the first portion and the ribs of the second portion each extend over the whole of the respective portion in the longitudinal direction.
9. The heat exchanger according to claim 1, wherein the conduit is a pipe comprising a combustion chamber or a pipe in fluid communication with a combustion chamber.
10. The heat exchanger according to claim 1, wherein the inner shell of the heat dissipating body further includes a third portion adjacent to the second portion, the third portion having at least two ribs transversally displaced in relation to each other, wherein at least one rib of the third portion is transversally displaced in relation to each rib of the second portion, or wherein at least one rib of the second portion is transversally displaced in relation to each rib of the third portion.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 shows a schematical cross section of an exemplary heat exchanger
(2) FIG. 2 shows a schematical top view of a first and a second segment of a cavity of the heat exchanger.
(3) FIG. 3 shows a shortened schematical inclined view of the first segment.
(4) FIG. 4 shows an unshortened schematical inclined view of the first segment.
(5) FIG. 5 shows a schematical top view of the heat dissipating body of the heat exchanger.
(6) FIG. 6 shows a schematical top view of the heat dissipating body of the heat exchanger according to a further embodiment.
(7) FIG. 7 shows a schematical top view of a segment according to a further embodiment.
(8) FIG. 8 shows a schematical top view of two segments according to a further embodiment.
(9) FIG. 9 shows a schematical top view of a heat dissipating body of a heat exchanger having the segments from FIG. 7.
(10) FIG. 10 shows a schematical view of an inner shell having three portions.
(11) FIG. 11 shows a flow chart of a method of manufacturing a heat exchanger.
(12) FIG. 12 shows a schematical top view of two segments according to a further embodiment.
(13) In the present disclosure a top view is a presentation in which the longitudinal direction is perpendicular with respect to the drawing surface, if nothing else results from the context.
DETAILED DESCRIPTION
(14) In the following description of the drawings identical reference numbers refer to identical or similar components.
(15) FIG. 1 schematically shows an example of a heat exchanger 10 having an internal conduct 32 for conducting a fluid and having a heat dissipating body 12, 12 for dissipating heat of the fluid. The internal conduct 32 can be a hollow conduct, for example, a pipe. It can basically have any cross section, for example, a circular or quadratic cross section. In the example as shown the internal space 38 is a combustion chamber for the internal conduct 32. The internal conduct 32 may therefore referred to as fire tube. During operation a combustible material (not shown) is combusted in the combustion area 40. Thereby, hot exhaust gas is generated. The internal conduct 32 comprises an orifice 42 through which the hot exhaust gas exits from the internal conduct 32.
(16) The heat dissipating body 12, 12 comprises a cavity 14, 14 extending in a longitudinal direction 36. The heat dissipating body 12, 12 and/or the internal conduct 32 may have a rotational symmetry axis 16. In this case, the longitudinal direction 36 is parallel with respect to the rotational symmetry axis 16. Within the cavity 14, 14 at least one end portion of the internal conduct 32 extends, referred to as end piece 34. The end piece 34 comprises the orifice 42. The orifice 42 faces a bottom surface 44 of the cavity 14, 14. In operation, a fluid, in this example hot exhaust gas, flows out of the internal conduct 32 over the orifice 42 into a bottom area 46 of the cavity 14, 14 (in the drawing, the flow is indicated by arrows).
(17) Between an outer shell 48 of the internal conduct 32 and an inner shell 20, 20 of the heat dissipating body 12, 12, a flow space for conducting the fluid away from the bottom area 46 is designed. The flow space extends in the longitudinal direction 36. The inner shell 20, 20 of the heat dissipating body 12, 12 comprises a first portion 20 and a second portion 20 adjacent to the first portion 20. According to an alternative (not shown) of the embodiment as shown, the heat dissipating body 12, 12 comprises a lateral exit for letting out the fluid.
(18) The first portion 20 comprises at least two ribs 22 (see FIGS. 2 to 9) that are transversally displaced in relation to each other. Transversal means perpendicular with respect to the longitudinal direction 36. The second portion 20 comprises at least two ribs 22 that are transversally displaced in relation to each other. Moreover, each rib 22 of the second portion 20 is transversally displaced in relation to each rib 22 of the first portion.
(19) In the example (see FIG. 1) the heat dissipating body 12, 12 comprises a first segment 12 and a contiguous second segment 12. The first segment 12 may be cup shaped. The second segment 12 may be ring shaped. In the example the cup shaped first segment has a bottom portion, the inner surface of which forms the bottom surface 44 of the cavity. The first portion 20 of the inner shell 20, 20 of the heat dissipating body and a first portion 14 of the cavity 14, 14 are assigned to the first segment 12. The second portion 20 of the inner shell 20, 20 of the heat dissipating body and a first portion 14 of the cavity 14, 14 are assigned to the second segment 12.
(20) FIG. 2 schematically shows a first segment 12 and a second segment 12 of a heat dissipating body. In the example as shown, both segments 12 and 12 are identically constructed. In order to avoid repetitions, only the first segment 12 is described now. The segment 12 essentially comprises a ring shaped or pipe shaped segment body 24 through which a cavity 14 is passing. In the example as shown, the segment body 24 has a quadratic outline, however different shapes are possible. According to a preferred embodiment (not shown), the outline of the segment body 24 is circular. At least two ribs 22, in the example as shown exactly four, protrude from the segment body 24 into the cavity 14. The segment body 24 and the ribs 22 can be designed in one piece. The segment body 24 and the ribs 22 are preferably manufactured from a material having a high heat conductivity, for example, from a metal or from an alloy. The segment 12 comprises an inner shell 20 defining the cavity 14, the shell 20 forming the mentioned first portion in the heat exchanger. The four ribs 22 each are displaced relative to each other by 90 in relation to a rotational symmetry axis 16. Therefore, the example of a segment 12 as shown here is symmetrical under rotation of 90 about the rotational symmetry axis 16. In operation of the heat exchanger, the fluid, for example, hot exhaust gas, flows through the cavity 14 in a main flow direction, being parallel to the rotational symmetry axis 16 in the example as shown. In the example as shown, each of the ribs 22 extends along the longitudinal direction, i.e. parallel to the symmetry axis 16, over the whole of the inner shell from the entrance area to the exit area of the segment body 24. In another example (not shown) one or more ribs are shorter than the respective portion, i.e. they do not extend over the whole of the portion. According to an alternative of these examples, the ribs 22 that extend in transversal direction (here in radial direction) are shorter than the ribs 22.
(21) FIG. 3 shows a schematical inclined view of the segment 12 in which for clarity reasons the segment 12 is shown in a shortened manner. According to a preferred embodiment, the ribs are elongated along the longitudinal direction (see the unshortened presentation in FIG. 4). This makes it possible to generate a comparably long heat exchanging path using a comparably small number of segments.
(22) FIG. 5 schematically shows two segments 12 and 12 (compare FIG. 2) of a heat dissipating body of a heat exchanger 10. The heat dissipating body in addition has a bottom segment (not shown) that corresponds to the segment 12 in FIG. 1. The heat dissipating body 12, 12 serves for transferring heat from the fluid to the heat dissipating body 12, 12 or from the heat dissipating body 12, 12 to the fluid. The heat dissipating body 12, 12 comprises a cavity 14, 14 that is assembled from the cavities 14 and 14 and through which fluid can flow along a longitudinal direction. In FIG. 4 the flow path is perpendicular to the drawing surface. The inner shell 20 of the first segment 12 forms a first section of the inner surface 20, 20 of the heat dissipating body 12, 12. The inner surface 20 of the second segment 12 forms a second portion of the inner shell of the heat dissipating body 12, 12 adjacent to the first portion 20. The first portion 20 therefore comprises at least two ribs 22 in the example as shown, exactly four ribs 22. Also, the second portion 20 comprises at least two ribs 22, in the example as shown, exactly four ribs 22.
(23) As can be gathered from FIG. 5, the ribs 22 and 22 of the first segment 12 and the second segment 12, respectively, are transversally displaced to each other, i.e. transversal in relation to the main flow direction. In the example as shown, this is achieved by an arrangement in which the second segment 12 is rotated by 45 about the common rotational symmetry axis 16, 16 in relation to the first segment 12. More exactly, each rib 22 of the second portion 20 is transversally displaced in relation to each rib 22 of the first portion. The part of the cavity 14 that is situated between two adjacent ribs 22 is also referred to as channel 26 in this disclosure (see FIG. 2). The same applies in analogy with respect to the second segment 12. The segments 12 and 12 therefore each comprise two channels 26 and 26, respectively. In the example as shown there are exactly four channels 26 and 26, per segment. The displacement of the ribs 22 in relation to the ribs 22 as described with reference to FIG. 5 results into the fact that each channel 26 meets a rib 22 at the border between the two segments 12 and 12, while each rib 22 meets a channel 26. This arrangement promotes a mixing within the fluid that flows through the heat dissipating body 12, 12.
(24) In the geometry shown in FIG. 5, an additional sealing between the segments 12 and 12 may be required in the regions 28 and 28 that are not closed. Advantageously, these segments 12 and 12 are designed such that in between no potential leaks occur (compare FIG. 6).
(25) FIG. 7 schematically shows an example of a segment 12 having exactly eight ribs 22 and an octagonal profile. In further examples (not shown), the segment 12 has more than eight ribs.
(26) FIG. 8 and FIG. 9 show an example of an embodiment in which the heat dissipating body comprises a first and an identically constructed second segment having the first portion and the second portion, respectively, wherein the first segment and the second segment are rotated about an axis that is perpendicular in relation to the longitudinal direction by 180. Both of the segments may for example be designed as essentially rectangular frames, wherein several parallel equidistant ribs are formed on two opposing inner surfaces of each frame. In the example as shown, the segment bodies 24 and 24 of the segments 12 and 12, respectively, comprise an essentially rectangular cross section. The arrangement of the second segment 12 as shown in FIG. 8 results from the arrangement in the first segment 12 by rotating the segment 12 by 180 about an axis 30 that is perpendicular with respect to the main flow direction.
(27) FIG. 10 schematically shows an example of an embodiment in which the inner shell of the heat dissipating body comprises at least three consecutive portions, for example a first portion having ribs 22, a subsequent second portion having ribs 22 and a third portion consecutive to the second portion having ribs 22. The design options and advantages described in this disclosure with respect to the combination of the first and the second portions may be correspondingly transferred on the combination of the second and the third portions. The third portion may, for example, be a repetition of the first portion, i.e. it can be geometrically similar to the first portion. From a geometrical view, the third portion may be transferrable into the first portion by a translation in the longitudinal direction. In the example as shown, each rib 22 of the first portion and each rib 22 of the third portion are transversally displaced in relation to each rib 22 of the second portion. However, each rib 22 of the first portion is aligned with each rib 22 of the third portion.
(28) The inner shell may comprise an alternating sequence of N portions. The number N of portions may for example be 3, 4, 5, 6 or more. The portions may be numbered 1 to N. The sequence may be alternating in this sense that each portion having the number I+2 (I=1 to N2) is transferrable in the portion having the number I, by using a geometrical, i.e. an abstract or hypothetic, translation parallel to the longitudinal direction. Such an embodiment results in a high heat exchange rate. Each portion may be realized by a module or segment, making an efficient manufacturing possible.
(29) An example of a manufacturing method is illustrated by the flow chart in FIG. 11. In a first step S1 single segments are manufactured. Preferably, at least two segments are identical in order to minimize the costs of the manufacturing process. In a subsequent step S2, the segments are assembled, such that the single cavities of the segments merge into a single continuous cavity. Preferably, the segments are directly welded to each other, i.e. without the use of intermediate elements and, particularly, without the use of sealings. In doing so, directly consecutive segments are arranged such that the ribs of the following segment are transversally displaced in relation to the ribs of the preceding segment.
(30) The top view in FIG. 2 schematically shows an example of an embodiment in which each rib 22 of the first portion 20 completely or in part covers a channel 26 of the second portion. Hence, the face surface of the rib 22 that faces the second portion 20 completely covers the transversal cross section of the channel 26 at the beginning or at the end of the channel facing the first portion 20. In other words, the cross section of the channel 26 at the beginning or at the end of the channel facing the first portion 20 is projected completely on the face surface of the rib 22 facing the second portion 20.
(31) In the example, the face surface of a rib 22 of the first portion 20 facing the second portion 20 is greater than the cross section of the channel 26 covered from this rib 22 at its beginning or end of the channel facing the first portion 20. The face surface of the rib 22 facing the second portion 20 completely overlaps the cross section of the channel 26 at its beginning or its end of the channel facing the first portion 20, while the cross section of the channel 26 at its beginning or its end of the channel facing the first portion 20 only partly overlaps the face surface of the rib 22 facing the second portion 20.
(32) In an alternative (not shown) of this example, a channel 26 of the second portion 20 and a rib 22 of the first portion 20 completely overlap each other transversally. Hence, the face surface of the rib 22 facing the second portion 20 completely overlaps the cross section of the channel 26 at its beginning or its end of the channel facing the first portion 20, and the cross section of the channel 26 also completely overlaps at its beginning or its end of the channel facing the first portion 20 the face surface of the rib 22 facing the second portion 20. Hereby a good heat exchange is achievable using an amount of material for the ribs as small as possible.
(33) Further, in the example according to FIG. 12, at least one of the ribs 22 of the first portion 20 is higher than each of the ribs 22 of the consecutive second portion 20. The height of a rib is its transversal dimension, starting from the internal conduct 32, i.e. from the base of the rib. In other words, in this example at least one of the ribs 22 of the first portion 20 further extends into the cavity 14 in a transversal direction (compare FIG. 1) than the ribs 22 of the consecutive second portion 20. If a concentrical design of the heat dissipating body is provided, as for example in the embodiment according to FIG. 7, the height of a rib can be defined as its radial dimension. If higher ribs are provided, a higher heat flow may be achieved. A larger height of the rib on the first portion 20 can be of particular advantage, if the first portion is upstream in relation to the second portion as for example in FIG. 1, since in this case the gas is expected to be warmer on the first portion than on the second portion. For example, the first portion 20 may comprise at least one rib 22 that is at least 10%, at least 20%, at least 50% or even at least 100% higher than the rib 22 of the second portion 20.
(34) The ribs 22 and 22, respectively, of each portion are closely packed according to the example of FIG. 12. For example, the distances of adjacent ribs of a portion are small as compared to a dimension or thickness of the rib measured transversal with respect to the longitudinal direction. Alternatively or additionally, at least at one or even at each point of the first and/or the second portion, the combined cross section of all ribs defined at this point, is larger than the combined cross section of the channels formed between the ribs. The combined cross section of the ribs and the channels, respectively, is the sum of the cross sections of the single ribs and channels, respectively, at the respective point, i.e. in the respective transversal plane.
(35) The features explained with reference to FIG. 12 may be transferred in an analog manner to each of the embodiments according to FIGS. 1 to 10. For example, in the case of a concentrical design according to FIG. 7, it can be advantageous for the generation of turbulences that the ribs 22 of the first portion 20 have a greater height, i.e. a greater radial dimension, than the ribs 22 of the second portion 20. In this case, the distance from the rotational symmetry axis 16 to a rib 22 of the first portion is smaller than the distance from the rotational symmetry axis 16 to a rib 22.
(36) In each of the embodiments described herein, the ribs extend in a transversal direction within the cavity 14, 14, however, not necessarily to an opposing surface of the cavity. In other words, it may be provided that at least one or even each of the ribs 22 and 22, respectively, protrude into the cavity 14, 14 in a transversal direction, without meeting another solid structural element. Therefore, each of the ribs has only one contiguous surface, and not several of them, that is circulated around by the fluid. The ribs can therefore be referred to as fins. In particular, it may be provided that the whole cavity 14, 14 is a contiguous spatial area. Thereby, a forming of turbulence patterns covering a relatively large space and of a good heat transport within the flowing fluid is allowed.
(37) The features of the invention as disclosed in the preceding description, in the drawings and in the claims may be essential for realizing the invention, as well in single appearance as well as in any combination. Several means at least two. For each feature as explained with respect to a single rib 22 or 22, it is contemplated that it may be advantageous that more or the most or all of the ribs 22, 22, respectively, may comprise the features of interest. Further, with respect to each feature explained with reference to a single channel 26 or 26, it may be advantageous that more or the most or all of the channels 26 and 26, respectively, comprise the feature of interest.
REFERENCE NUMERAL LIST
(38) 12 first segment 12 second segment 14 cavity 14 cavity 16 rotational symmetry axis 16 rotational symmetry axis 22 rib 22 rib 20 first portion 20 second portion 24 segment body 24 segment body 26 channel 26 channel 30 axis 32 internal conduct 34 end piece 36 longitudinal direction 38 internal space 40 combustion area 42 orifice 44 bottom surface 46 bottom area 48 outer shell
