Abstract:
A heat exchanger with mutually adjacent first flow channels and second flow channels. The first flow channels and the second flow channels are received in a first manifold at a first end region of the flow channel end regions and in a second manifold at a second end region of the flow channel end regions. The first manifold has a first base and the second manifold has a second base, the first base and second base having a plurality of openings in which the end regions of the flow channels are received. The first manifold has a first longitudinal channel and a second longitudinal channel. The second manifold has a second cover which together with the second base of the second manifold forms transverse channels, and one first flow channel and one second flow channel are fluidically connected to each other via a respective transverse channel.

Description:
This nonprovisional application is a continuation of International Application No. PCT/EP2014/053627, which was filed on Feb. 25, 2014, and which claims priority to German Patent Application No. 10 2013 203 222.6, which was filed in Germany on Feb. 27, 2013, and which are both herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a heat exchanger with mutually adjacent first flow channels and second flow channels, whereby the first flow channels and the second flow channels at a first end region are received in a first header and at a second end region in a second header, whereby the first header has a first base and a first cover and the second header has a second base and a second cover, whereby the first base and the second base have a plurality of openings in which the end regions of the flow channels are received, whereby the first header has a first longitudinal channel and a second longitudinal channel, whereby the first flow channels are in fluid communication with the first longitudinal channel and the second flow channels are in fluid communication with the second longitudinal channel. 
     Description of the Background Art 
     Apart from known PTC (positive temperature coefficient) heating elements, heat pumps can also be used for climate control, particularly for the heating, of electric vehicle and hybrid vehicles but also in conventionally powered motor vehicles. To enable the greatest possible range for vehicles, a lowest possible power requirement of the climate control system is preferred. 
     The use of a heat pump is advantageous in comparison with the use of a PTC heating element, because the power requirement is much lower. The power requirement of a heat pump is approximately half as a great as the power requirement of a PTC heating element. 
     The heat exchanger, which functions as a condenser in the heat pump mode of a climate control system and is thereby used as a heat source for heating the passenger compartment, is often integrated into the climate control unit itself. The result is that only a small installation space is available for the condenser. This is especially disadvantageous for the temperature distribution within the condenser. 
     Two-row arrangements of the condenser can be used nevertheless to achieve an advantageous temperature distribution in the condenser, particularly in the condensation of the refrigerant. These are characterized in that two rows of tubes are arranged one behind the other in the air flow direction. 
     Designs with two headers per row in each case are known in the prior art for the realization of two-row condensers. This results in disadvantages, such as a higher required refrigerant amount, a more laborious soldering of the components, or a tightness of the connections that is difficult to produce. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention provide a heat exchanger that is optimized compared with the prior art. It is an object of the invention further to provide an arrangement of a heat exchanger in a climate control system. 
     An exemplary embodiment of the invention relates to a heat exchanger with mutually adjacent first flow channels and second flow channels, whereby the first flow channels and the second flow channels at a first end region are received in a first header and at a second end region in a second header, whereby the first header has a first base and a first cover and the second header has a second base and a second cover, whereby the first base and the second base have a plurality of openings in which the end regions of the flow channels are received, whereby the first header has a first longitudinal channel and a second longitudinal channel, whereby the first flow channels are in fluid communication with the first longitudinal channel and the second flow channels are in fluid communication with the second longitudinal channel, whereby the second header has a second cover, which together with the second base of the second header forms cross channels, whereby in each case a first flow channel and a second flow channel are in fluid communication with one another via a cross channel. 
     The heat exchanger can be designed such that a fluid can flow via a fluid inlet into one of the longitudinal channels, for example, the first longitudinal channel, of the first header and can be distributed there via the flow channels associated with the particular longitudinal channel. The fluid then flows through the particular flow channels, for example, the first flow channels, and is redirected in the second header into the further flow channels, for example, the second flow channels. To this end, the second header forms cross channels, which in each case fluidically connect a first flow channel to a second flow channel. The fluid then flows back into the first header, but here in the further longitudinal channel, for example, the second longitudinal channel. From there, the fluid can flow out of the heat exchanger via a fluid outlet. 
     The first and second flow channels can each be arranged in rows and mutually adjacent, so that the first flow channels form the first row of the heat exchanger and the second flow channels the second row. The first and second rows are arranged one behind the other in the main flow direction of the fluid, flowing around the flow channels. 
     The cross channels can be oriented so that in each case flow channels from the first row are connected to the flow channels from the second row. The longitudinal channels, in contrast, are oriented so that they connect a plurality of flow channels of a row with one another. In general, a transverse orientation here stands for an orientation of an element of one row to the respective further row of flow channels. A lengthwise orientation here stands for an orientation of an element along a row of flow channels. 
     The volume of fluid required overall within the heat exchanger can be reduced by a fluidic connection of in each case a first flow channel with in each case a second flow channel, because the second header has a smaller internal volume overall than a conventional header. This is especially advantageous. 
     The cross channels in the second header, moreover, represent a tolerance compensation for the flow channels inserted in the bases of the headers and formed by tubes. In addition, they facilitate the fluid transfer from the flow channels into the headers in that they increase the volume of the header at the end region of the flow channels. 
     The first cover together with the first base can form pockets, which in each case can be arranged in alignment with one of the openings of the first base and/or with the ends of the flow channels. 
     The pockets in the first longitudinal channel, like the cross channels in the second flow channel, also can serve as tolerance compensation for the tubes inserted in the openings of the first base. In addition, the arrangement of the pockets is advantageous to achieve a better fluid flow from the longitudinal channels into the flow channels or vice versa. 
     An exemplary embodiment provides that the second cover has a wave-like contour in a longitudinal section, whereby in each case the wave troughs can be in contact with the base of the second header and the wave peaks together with the connecting elements form the second cross channels. 
     The second cover can be formed from a metal strip, which has a wave-like contour, which has been created, for example, by a forming process. The wave peaks in the fully assembled state are positioned so that they lie opposite to the passages of the second base. The fluid transfer occurs from the particular flow channels into the cross channel formed by the wave peak. The first flow channels are in fluid communication with the second flow channels via the cross channel. 
     The wave troughs in this case can be in direct contact with the second base and, for example, can be soldered, glued, or welded with it. A fluid-tight separation of the cross channels from one another is achieved in this way. 
     The wave troughs and the wave peaks in each case can lie in a mutual plane, whereby the wave-like contour can be made as a rounded wave profile or as a rectangular profile or as a trapezoidal profile. 
     This is especially advantageous, because due to the arrangement of the wave troughs and wave peaks in each case in one plane, it is especially simple to connect the cover to the base by a material bonding method, because large areas of the cover are in extensive contact with areas of the base. 
     The openings in the bases can have passages, whereby the passages can be directed away from the interior of the headers toward the flow channels. 
     In order to keep the internal volume of the header as small as possible, it is especially advantageous if the passages are oriented away from the interior of the headers. An increase in the stability of the heat exchanger can thus be achieved by the passages, because the tubes of the flow channels are run in the passages; at the same time, the headers can be dimensioned in such a way that a lowest possible internal volume is required, which leads to a reduction in the required amount of fluid. 
     In an embodiment of the invention, it is provided in addition that the bases on the longitudinal sides can have at least partially upstanding edge regions, which laterally close the longitudinal channels and/or the cross channels and/or the pockets. 
     The upstanding edge regions can have a bottom edge region, which is formed by a continuous metal strip, whereby a plurality of crenellated sealing elements upwardly join to the bottom edge region. 
     The at least partially upstanding edge regions of the bases facilitate the positioning of the cover in the assembly process. At the same time, a lateral sealing of the longitudinal and/or cross channels and/or pockets can be achieved via the edge regions. The covers can be dimensioned so that in the fully assembled state they abut against the upstanding edge regions and particularly against the crenellated sealing elements, which join to the bottom edge region. The fluid-tight connection between the covers and the upstanding edge region can then be created by methods such as, for example, soldering, gluing, or welding. 
     It can be provided in an embodiment of the invention that the at least partially upstanding edge regions can have fixing elements via which the covers can be fixed to the bases. 
     The covers can be fixed in the bases at the edge regions via the fixing elements until a permanent fluid-tight connected is created. This can be achieved, for example, via lugs which upon insertion of the covers come into contact with them and fix the covers. 
     It can be provided according to an embodiment of the invention that the pockets in the first cover can be formed by indentations, which are introduced into an edge running laterally parallel to the first longitudinal channel and to the second longitudinal channel and in each case merge into the first longitudinal channel or the second longitudinal channel. 
     In order to utilize the installation space as optimally as possible, it can be provided that the passages or the tubes of the flow channels can extend over the entire width of the longitudinal channel. Because for the purpose of attachment to the base the cover usually has an edge that lies flat against it, it can be advantageous to provide the edge with indentations in the areas lying opposite to the passages. It can be prevented with the indentations that the passages are covered by the edge of the cover and thus the area by means of which a fluid transfer between the header and the flow channels can occur is reduced. 
     By means of the above-described design of the edges, the header can be made narrower than in an embodiment without indentations in the edges and thereby nonetheless have the same fluid transfer area as a wider header. 
     Moreover, the cross channels and/or pockets and/or passages can have a variable cross section. 
     The cross channels and/or pockets and/or passages can have a variable cross section. Designs with favorable flows can be realized in this way. The design of the passage or cross channel can occur, for example, such that flow out of the flow channel is promoted, for instance, in that the passage widens trumpet-like in the fluid flow direction. In addition to a widening or a narrowing, it can also be provided, for example, that the contours of the cross channels or passages are rounded off to prevent the fluid flow from backing up in the area of sharp edges or corners or being negatively affected in some other way. 
     An exemplary embodiment provides that the first longitudinal channel and/or the second longitudinal channel have one or more partition walls that divide the particular longitudinal channel into a number of sections. 
     The throughflow sequence of the heat exchanger can be influenced by the arrangement of one or more partition walls in one or more longitudinal channels. This is especially advantageous, if the aim is to achieve that the fluid in the interior of the heat exchanger is to flow back and forth repeatedly between the first and second headers. The partition walls can divide the longitudinal channel into a number of sections which are flown through one after another. The fluid inlet and the fluid outlet are to be adapted accordingly. 
     An exemplary embodiment also relates to the arrangement of a heat exchanger in a climate control system, whereby the heat exchanger is a two-row condenser and is arranged within a climate control unit of a climate control system, whereby the first flow channels form the first row and the second flow channels form the second row, whereby a first fluid can flow through the first flow channels and the second flow channels and a second fluid can flow around them. 
     An arrangement of a heat exchanger as described above in a climate control system is especially advantageous, because it is characterized in particular by a compact construction and therefore can be easily integrated into the small available space in a climate control unit of a climate control system. The two-row construction of the heat exchanger simultaneously assures a high heat exchanger efficiency. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
         FIG. 1  shows a flow-through principle of a heat exchanger of the invention; 
         FIG. 2  shows a view of the first header on a heat exchanger block, whereby the header is formed by two longitudinal channel and a plurality of pockets and the heat exchanger block is formed by a plurality of flow channels between which heat transfer elements are arranged; 
         FIG. 3  shows a further view of the first header of  FIG. 2 ; 
         FIG. 4  shows a further view of the first header looking toward the passages facing away from the interior of the header, but without the attached heat exchanger block; 
         FIG. 5  shows a further view of the first header according to  FIG. 4  looking toward the header side facing the heat exchanger block; 
         FIG. 6  shows a view of a base of the first or second header, looking toward the base side facing away from the heat exchanger block; 
         FIG. 7  shows a view of the cover of the first header, looking toward the inner side of the cover, which forms two longitudinal channels and a plurality of pockets with the associated base; 
         FIG. 8  shows a view of the second header on the heat exchanger block, whereby the second header forms a plurality of cross channels, via which the first and second flow channels are in fluid communication with one another; 
         FIG. 9  shows a perspective side view of the second header without the heat exchanger block; 
         FIG. 10  shows a perspective view of the second cover of the second header, whereby the cover has a wave-like contour; and 
         FIG. 11  shows a front view of the heat exchanger with the left and right header. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an illustration of a flow-through principle of a heat exchanger. The heat exchanger in this case includes two rows of flow channels  5 ,  6 , arranged one behind the other. A fluid can flow via a fluid inlet  1  into a first longitudinal channel  3 , formed by a side header. The fluid within longitudinal channel  3  is distributed to flow channels  5  leading to the second header. The fluid flows through flow channels  5  and is redirected in the second header, forming cross channels  7 , to the further flow channels  6 , which lead back from the second header to the first header. The fluid flows out of flow channels  6  into second longitudinal channel  4 , formed by the first header, and through fluid outlet  2  out of the heat exchanger. 
     A second fluid, for example, air, flows around the rows of flow channels  5 ,  6  along flow direction  8 , said rows being arranged behind one another. 
     The flow-through principle shown in  FIG. 1  represents a possible form for the flow through a two-row heat exchanger. The introduction of partition walls within longitudinal channels  3 ,  4  can also realize a flow different from the principle shown in  FIG. 1 .  FIG. 1  is used for the easy understandability of the structure of the heat exchanger following in  FIGS. 2 to 10 . 
       FIG. 2  shows a heat exchanger  10 , formed substantially by a plurality of tubes  12 , between which a plurality of heat transfer elements  11  are arranged. Heat transfer elements  11  can be made, for example, with a corrugated fin design. 
     Tubes  12  with heat transfer elements  11  together form heat exchanger block  13  of heat exchanger  10 . 
     The individual tubes  12  each have two end regions. A first end region opens into header  27  arranged on the left in  FIG. 2 . The second end region of tubes  12  opens into header  33  arranged on the right. Right header  33  will be described in greater detail in  FIGS. 8 to 11 . 
     First header  27  is formed substantially of a base  15  and a cover  16 . Base  15  has a plurality of passages  14 , which receive the specific end regions of tubes  12 . Passages  14  run around openings in base  15 , said openings not being shown in  FIG. 1 . 
     The formation of passages  14  serves in particular to increase the stability of the connection between tubes  12  and header  27 . Passages  14  in this case are arranged on a region of base  15 , said region facing away from the interior of header  27 , and point towards heat transfer block  13 . 
     Base  15  of header  27  has laterally upstanding edge regions  22 . Upstanding edge regions  22  close first header  27  toward the side. The more specific structure of base  15  will be discussed in the following figures. 
     A cover  16  is inserted in base  15 . Cover  16  due to its shape forms a first longitudinal channel  17  and a second longitudinal channel  18 . Furthermore, cover  16  has a plurality of pockets  21 . Said pockets are positioned in cover  16  such that in the fully assembled state pockets  21  are opposite to passages  14  and thereby to tubes  12 . The more precise structure of cover  16  will also be discussed in the following figures. 
     Upstanding edge region  22  of base  15  furthermore has sealing elements  20  and fixing elements  19 . Said fixing elements  19  serve to attach cover  16  to base  15  until a final connection is made between base  15  and cover  16  via a material bonding method, such as, for instance, soldering, gluing, or welding. Sealing elements  20  close pockets  21  and/or longitudinal channels  17 ,  18  on the side in the region that is not covered by bottom edge region  29 , formed by a continuous material strip. 
     Designs conventional in the art can be used for the embodiment of fixing elements  19 . Here, for example, catches can be bent on cover  16 , so that they are fixed to base  15 . Projections, which protrude over edge region  22  in the region of cover  16  and prevent a slipping out of cover  16 , can be provided inter alia. 
       FIG. 3  shows a further perspective view of the arrangement of heat exchanger  10  from  FIG. 2 . 
     It can be seen in  FIG. 3  that pockets  21 , which project laterally over longitudinal channel  17  or  18 , are closed on the sides by sealing elements  22 . Pockets  21  are made aligned with passages  14  and tubes  12  inserted in passages  14 . Pockets  21  are used substantially to facilitate the flowing in or out of the fluid in tubes  12 . Pockets  21  in this case merge into longitudinal channel  17  or  18 . A fluid can flow back and forth unimpeded between longitudinal channels  17  or  18  and the respective pockets  21 . 
     Furthermore, a tolerance compensation of tubes  12  is possible by means of pockets  21 . The shaping of pockets  21  increases the internal volume within first header  27  via tubes  12 . 
     Sealing elements  20  are made as a crenellated enlargement of bottom edge region  29  of upstanding edge region  22 . Base  15  can be made advantageously from a single metal blank by stamping methods and forming methods. This makes the production of base  15  simple and cost-effective. 
     Furthermore, partition wall  23  which is formed by cover  16  can be seen in  FIG. 3 . It can be seen in a cross section of first header  27  that first header  27  has a B-shaped contour. In this regard, the back of the B is formed by the planar region  24  of base  15  and the two arches of the B by the physical form of cover  16 . 
     Cover  16  in each case has an edge  25  on the left and right next to longitudinal channels  17 ,  18 . This edge is used substantially as a contact surface of cover  16  with base  15 , so that a material connection can be made later between the two elements. 
     Pockets  21  are introduced as indentations in said edge  25 . This is especially advantageous, because header  27  must have a smaller width overall in order to be able to receive tubes  12  and to be able to supply these with a fluid over the entire opening area of tubes  12 . If no indentations are provided in edges  25 , part of cover  16  would cover the openings of tubes  12  or passages  14  and thus reduce the effectively usable through-flow area of the tubes. This would have a disadvantageous effect on the efficiency of heat exchanger  10 . 
     A most compact possible configuration with the maximum possible performance is advantageous in particular with respect to the preferred field of application of such a heat exchanger  10  within a climate control system. 
     Cover  16  can also be produced by simple shaping methods from a single blank. Overall, header  27  can thus be produced in a simple manner and particularly cost-effectively. 
       FIG. 4  shows a further perspective view of first header  27 . The rest of the heat exchanger or heat exchanger block  13  is not shown in  FIG. 4 . It can be seen on the bottom side of planar region  24  of base  15  how a plurality of passages  14  are arranged substantially in two rows next to one another. The left half of passages  14  is thereby associated with the first row of tubes  12 , and the right half of passages  14  is associated with the second row of tubes  12 . Partition wall  23  of cover  16  is situated in the middle between passages  14 . Thus, a partitioning of the internal volume of header  27  in longitudinal channels  17 ,  18  is achieved. Each passage  14  in each case is in fluid communication with only one of longitudinal channels  17 ,  18 . 
     In alternative embodiments, it can also be provided that the passages do not project outwardly out of the header, but project inwardly into this header. 
       FIG. 5  shows a perspective view of base  15 , as it was already shown in the preceding figures. Apart from passages  14 , the planar region  24  of base  15  in particular and the upstanding edge region  22  can be seen with bottom edge region  29 , fixing elements  19 , and crenellated sealing elements  20 , which upwardly, away from planar region  24 , join to bottom edge region  29 . 
     In alternative embodiments, instead of the crenellated design of sealing elements  20 , it can also be provided to make bottom edge region  29  higher. This would require a greater amount of material, however, and thus increase the material costs of base  15  overall. 
       FIG. 6  shows a further view of base  15 , as it was already shown in  FIG. 5 . In  FIG. 6 , the view is directed toward the inner side of base  15  and particularly planar region  24  of base  15 . The design of fixing elements  19  in particular, which are formed as lugs and project over upstanding edge region  22  to the middle of base  15 , can be seen in  FIG. 6 . 
     A cover  16  must be pressed into base  15  past lugs  19  with a certain application of force. Lugs  19  then prevent an unintended falling of cover  16  out of base  15  until a final material connection is created. 
     It can be seen further in  FIG. 6  that passages  14  or openings  28  in base  15  to passages  14  run over the entire width of base  15  or planar region  24  of base  15 . The space between the particular passages  14  is provided as a connecting area for partition wall  23  with planar region  24 . The design of pockets  21  shown in the preceding figures assures that a fluid communication between the particular longitudinal channels  17 ,  18  and tubes  12  can occur over the full width of passages  14 . 
       FIG. 7  shows a perspective view of cover  16 . In  FIG. 7  the view is directed toward the inner side of cover  16 . Apart from the two longitudinal channels  17 ,  18  between which partition wall  23  is disposed, the structure of edge  25  with the plurality of indentations  26  can be seen. Indentations  26  form pockets  21 , which enable an inward flow of the fluid over the entire width of the opening of tubes  12  or passages  14 . As can be seen in  FIG. 7 , pockets  21  formed by indentations  26  merge into the associated longitudinal channel  17  or  18 . 
     Indentations  26  are made c-shaped, whereby the open side of the c-shaped arch is oriented in the direction of planar region  24  of base  15 . Different designs of the indentations can also be provided in alternative embodiments. For instance, rectangular or tapering trapezoidal indentations can be provided. The design of the sealing elements, which are connected to the bottom edge region of the upstanding edge regions, is to adapted if necessary to a different design of the sealing elements. 
     A different design of the cover can also be provided in alternative embodiments. Any design that provides for longitudinal channels separated from one another and that allows that in each case a first row of the flow channels is in fluid communication with a first longitudinal channel and in each case a second row of the flow channels is in fluid communication with a second longitudinal channel can be used for an implementation according to the invention. The configuration of cover  16  as shown in  FIG. 7  is especially simple and cost-effective to produce. 
     It can be seen, furthermore, in  FIG. 7  that in particular edges  25  and the foot region of partition wall  23  act as contact areas between cover  16  and base  15 . The arranging of edges  25  to the side of longitudinal channels  17  or  18  is especially important, to be able to produce a sufficient tightness of header  27 . The contact area between cover  16  and base  15 , which can be used for connecting the two elements, can be increased by edges  25 . This is especially important particularly during use as a condenser in a climate control system, because partially high pressures can occur here and a permanent tightness of the heat exchanger must be assured. 
       FIG. 8  shows a further perspective view of heat exchanger  10  with heat exchanger block  13 . The view in  FIG. 8  is directed toward right header  33 . In comparison with left header  27 , right header  33  has a plurality of cross channels  34 . The base of header  33  is identical to base  15  of header  27 , which was already described in the preceding figures. Only cover  30  of header  33  deviates from the configuration of header  27 . The precise structure of cover  30  is explained in the following figures. 
     In alternative embodiments, a different design of the base can also be provided for the second header. Any header that permits division of the internal volume into a plurality of cross channels, so that at least one flow channel of the first row can be brought into fluid communication with at least one flow channel of the second row via one of the cross channels, can be used for a design according to the invention. 
     The fluid, which flows through tubes  12  of one row into header  33 , is redirected by a plurality of cross channels  34  into the tube of the second row, said tube being located at the same height. Each cross channel  34  is in fluid communication with a tube of the front row and with a tube of the back row. 
     The required internal volume within header  33  is minimal due to this construction of header  33 . Each tube  12  is in fluid communication via only one cross channel  34  with its corresponding tube in the second row. In this way, disadvantageous backups of the fluid within header  33  can also not occur. 
     It can also be provided, moreover, in alternative embodiments to connect a plurality of tubes in the first row to a plurality of tubes in the second row via individual cross channels. This increases the required internal volume within header  33 , however, as a result of which the fluid requirement for operating heat exchanger  10  also increases. 
       FIG. 9  shows a perspective view of header  33  without the rest of heat exchanger block  13 . Header  33  is formed substantially of a base  15 , which likewise has a plurality of passages  14  and laterally upstanding edge regions  22 , and a cover  30 , which has a wave-like contour in the longitudinal section. Sealing elements  20  in each case close cross channels  34  toward the side. Each cross channel  34  is positioned so that it is aligned with two passages  14  of the base. The individual cross channels  34  are separated fluid-tight from one another by connecting sites between cover  30  and base  15 . As was also the case for first header  27 , cover  30  is fixed via fixing elements  19  within base  15 , until a material connection has been made between the two elements. 
       FIG. 10  shows cover  30  of header  33 . As already described in  FIG. 9 , cover  30  has a wave-like contour in the longitudinal section. Wave troughs  32  and wave peaks  31  in each case lie together in a plane. As a result, cover  30  can be connected especially easily to planar region  24  of base  15 . 
     Cover  30  in the exemplary embodiment shown in  FIG. 10  has a wave-like contour, whereby the waves are formed by a trapezoidal section. Connecting elements  35  of cover  30 , said elements connecting wave troughs  32  with wave peaks  31 , are each oriented such that cross channel  34  narrows from wave trough  32  to wave peak  31 . Two connecting elements  35  delimiting a cross channel  34  are inclined toward one another. 
     In alternative embodiments, wave profiles can also be provided, which are formed by rectangular sections in which the connecting elements are arranged at right angles to the particular wave trough or wave peak. In a further alternative, a wave contour following a sinusoidal course can also be provided. 
     Wave troughs  32  in this case form the contact sites between cover  30  and base  15 , by means of which the material connection occurs. Cross channels  34  are formed by connecting elements  35 , which connect wave troughs  32  with wave peaks  31  and wave peaks  31  themselves. The fluid communication between the tubes in the first row and the second row is assured by these cross channels. 
     Cover  30  can be produced by a shaping process from a blank. The production of cover  30  is therefore especially simple and cost-effective. Furthermore, a dimensioning of cover  30  on a heat exchanger with a greater or smaller number of tubes is possible in a simple way. 
     The shown embodiment and the described alternatives do not limit the possible embodiments. Any design of the cover that allows formation of a plurality of cross channels for connecting the flow channels of the first row to the flow channels in the second row can be provided. 
     Moreover, the embodiments of the rest of the figures are not limiting in nature. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.