This application claims benefit of and priority to German Patent Application No. 20 2011 052 186.9, filed Dec. 5, 2011, the content of which Application is incorporated by reference herein. No new matter has been added.
The present invention relates to a heat exchanger that includes a plurality of first flow channels for a cooling medium. The plurality of the first flow channels are configured to be located one over the other. Further included are a plurality of second flow channels for a process medium. One the plurality of the second flow channels is located between two of the plurality of the first flow channels. The plurality of the first and second flow channels each are formed from partition plates, and first and second block profiles are configured to hold the partition plates in a spaced-apart condition. Lamellae are arranged between the first and second block profiles. The first block profiles delimit the first flow channels and are configured to be C-shaped. Two legs are configured to be springy and extend in a direction of the lamellae from a base of the first block profiles and delimit a first recess open in the direction of and between the extended lamellae.
A heat exchanger is known, for example, from DE 202 08 748 U1. The heat exchanger described therein is used, in particular, for high-temperature applications, for example, in charge air coolers or oil coolers of motor vehicles, which are subject to significant thermal and mechanical stresses because of high cyclic temperature differences and cyclically changing flow rate quantities. These cyclic thermal stresses and the cyclic pressure stresses, in particular internal pressure stresses, act in particular on the components in the region of the supply of the hot medium, for example, in the form of undesired material extensions or compressions of the components of the heat exchanger, which are connected to one another by soldering to form a rigid block.
To lengthen the service life of such a heat exchanger, it is proposed, in the above-mentioned publication, that the block profiles of the heat exchanger, which hold spaced apart partition plates, which are arranged parallel to one another, and which block profiles, together with lamellae arranged between the partition plates, form the flow channels of the cooling medium and the flow channels of the process medium to be cooled, be provided on a side facing away from the lamellae with a central recess having legs, which are flexible transversely to the flow directions of the hot and cold medium and have the soldering surfaces, whereby one side of the block profile is implemented flexibly and can thus absorb forces or tensions perpendicularly to the flow directions.
However, it has been shown that in spite of the partially flexibly designed block profile, damage which decreases the lifetime of the heat exchanger block through cyclically occurring stresses cannot be adequately avoided.
Embodiments of the present disclosure provide for a heat exchanger which has a lengthened lifetime and which has even less danger of cracking.
Thus, the present disclosure relates to a heat exchanger including a plurality of first flow channels for a cooling medium. The plurality of the first flow channels are configured to be located one over the other. Further included are a plurality of second flow channels for a process medium. One the plurality of the second flow channels is located between two of the plurality of the first flow channels. The plurality of the first and second flow channels each are formed from partition plates, and first and second block profiles are configured to hold the partition plates in a spaced-apart condition. Lamellae are arranged between the first and second block profiles. The first block profiles delimit the first flow channels and are configured to be C-shaped. Two legs are configured to be springy and extend in a direction of the lamellae from a base of the first block profiles and delimit a first recess open in the direction of and between the extended lamellae. The base includes a second recess.
According to the present disclosure, the first block profiles delimiting the first flow channels are designed as both having C-shaped legs extending from a base of the block profiles in the direction of the lamellae and are also provided with a flexibly designed base.
Through the flexible design of the base of the block profiles, it is within the scope of the present disclosure to significantly reduce both the effects of pulsing or cyclic internal pressure stresses on the heat exchanger and also the effects of cyclic thermal stresses.
Thus, in the case of cyclic internal pressure stresses, the tensions acting on the lamellae arranged between each two of the first block profiles, for example, the flanks of the lamellae, which may be designed as turbulators in the edge region of the front process passages, are reduced by up to 40% through the flexible design of the first block profiles in relation to the known, or typical embodiment of block profiles. The lifetime of the heat exchanger block in accordance with the present disclosure, is thus increased by a factor of 4 to 5.
The tensions caused by cyclic thermal stresses on the lamellae arranged between each two of the first block profiles are also reduced by the flexible design of the first block profiles by approximately 30% in relation to the known, or typical embodiment of the block profiles.
The tensions caused by cyclic thermal stress on the partition plates at the edge of the first block profiles because of the thermal expansion in the block width direction are reduced to the same extent. That is done by the enlargement of the ratio of bending length to deflection of the partition plate in the event of a deformation of the partition plate and by a reduction of the cyclic temperature difference between the flexible first block profile and the lamellae, which lamellae may, for example, be designed as turbulators. The lifetime of the lamellae, which may be, for example, be designed as turbulators, in the process passages of the heat exchanger block is thus increased by a factor of 3 to 4. The lifetime of the partition plates is thus increased as a function of the thermal tensions caused by the thermal expansion in the block longitudinal direction by a factor of 1.5 to 3.
Embodiments of the present disclosure are discussed herein and in the appended claims.
According to an embodiment of the present disclosure, the base of the block profiles has recesses extending parallel to the running direction of the flow channels of the cooling medium, which are designed to be slotted, for example. Firstly, the flexibility of the block profile is thus increased, and secondly, the mass of the block profile is also reduced by the introduction of the recesses, so that the absorption capacity of the block profile is thus also reduced. Finally, an enlargement of the heat-transfer area on the block profile and therefore a reduction of the thermal tensions is achieved by the introduction of the recesses.
The ends of the recesses in the interior of the base are designed as widened, according to an embodiment of the present disclosure. This results in a further increase of the flexibility of the block profile, on the one hand, and also a further enlargement of the heat-transfer area of the block profile, on the other hand.
According to an embodiment of the present disclosure, the recesses are alternately arranged on the side facing away from the lamellae and the side facing toward the lamellae.
The sum of the length of the alternately arranged recesses may be, for example, greater than the length of the base of the first block profile, so that viewed in a longitudinal extension of the base, the ends of the recesses located in the interior of the base partially overlap.
Embodiments according to the present disclosure are further explained herein.
Other aspects of the present disclosure will become apparent from the following descriptions when considered in conjunction with the accompanying drawings.
In the following description of the Figures and discussion of the embodiments of the present disclosure, terms such as top, bottom, left, right, front, rear, for example, relate to the exemplary illustrations and the positions selected in the respective Figures of the heat exchanger, the block profile, the manifold box, and other elements shown, according to the present disclosure. These terms are not to be understood as restrictive, that is, these references may change through different work positions or the mirror-symmetric design, for example.
In
The length L and the depth T of the heat exchanger block 1 are defined by the dimensions of the rectangular partition plates 2.
As shown in
Between the manifold boxes 7, 8 and the lamellae 9, first block profiles 3 are arranged between the partition plates 2 on their frontal ends, in order to suitably equip the heat exchanger block 1 in the inlet region of the hot process medium to be cooled and the thermal and mechanical stresses accompanying this.
The flow channels 5 of the medium to be cooled are also formed by lamellae 10, which are arranged between each two partition plates 2, having second block profiles 6 terminating the flow channels 5 at the side edges. The second block profiles 6, as may be recognized in
The lamellae 10 forming flow channels 5 of the medium to be cooled may be, as shown in
Both the components of the heat exchanger block 1, and also the partition plates 2, the lamellae 9 and 10, and the first and second block profiles 3 and 6 may, for example, include aluminum and are fixedly connected to one another by soldering to form a rigid block. Other heat exchanger active materials such as copper, copper alloys, and steel are within the scope of the present disclosure.
In order to reduce the effects of cyclic internal pressure stresses on the heat exchanger and also the effect of cyclic thermal stresses, the first block profiles 3 may, for example, be designed to be springy. For this purpose, on the one hand, such a block profile 3 is designed on an end facing toward the lamellae 9 as C-shaped, as is known from the prior art, as shown in
According to an embodiment of the present disclosure, a side facing away from the lamellae 9 and facing toward the inflow region of the medium to be cooled, which is designated hereafter as the base 31 of the first block profiles 3, is also designed to be springy.
As shown in
In order to keep the force, which is exerted from the base 31 of the first block profile 3, on the second lamellae 10, which are, for example, designed as turbulators, and the partition plates 2, as a result of the cyclic heating and cooling by entry of the medium to be cooled into the front manifold boxes 7 and into the second flow channels 5 or as a result of the cyclic internal pressure stresses as small as possible, the base 31 of the block profiles is also designed to be springy on a side facing away from the lamellae 9 forming the flow channels 4 of the cooling medium.
The springy design is performed, for example, by recesses 38, which extend parallel to the flow direction X of the flow channels 4 of the cooling medium, and by which the base 31 of the first block profile 3 is divided on the side facing away from the lamellae 9 into outer webs 36 and at least one inner web 37. These recesses 38 may, for example, be designed as slots having a slot depth m, the slot depth m being in a ratio of 0.4≦m/b≦0.9 in relation to the width b of the base 31.
The slot depth m may, for example, be additionally at least 1 mm less than the seam thickness of the weld seam 15, which is designated as the a dimension, or height of the triangle insertable into an arbitrary seam shape, via which the manifold boxes 7, 8 are connected to the front sides of the heat exchanger block 1 on the entry or exit side of the process medium, respectively.
The width h 1 of these slotted recesses 38 may, for example, be in a ratio to the total width h of the first block profile 3 of: 0.1≦h1/h≦0.3.
The recesses 33 between the legs 32 of the first block profile 3 may, for example, be designed as circular having a diameter d. The circular recess 33 opens toward the lamellae 9 to form an opening gap 34 having a width e.
An embodiment according to the present disclosure, in relation to the embodiment of the first block profile 3 shown in
In the embodiment shown in
Further embodiments of the first block profile 3, according to the present disclosure, are described hereafter and are shown in
In an embodiment of the first block profile according to
In the embodiment shown in
The length of all recesses 38 extending from the side facing away from the lamellae 9 into the base 31 of the block profiles 3 may, for example, always correspond to the above-mentioned length m.
In the embodiment of the first block profile 3 shown in
The length t of the depressions 361 in the direction of the longitudinal extension L of the heat exchanger block 1 may, for example, correspond to the difference of the length b of the base 31 of the first block profile 3 and the length m of the recesses 38 multiplied by a factor of 1.1 to 3.
The depression 361 may, for example, be designed as a trough in the form of a circular section, whose radius of curvature R may, for example, correspond to the equation R=0.5+(0.15−1.15)*(b−m)2.
In the embodiment shown in
In the embodiment of the first block profile 3 shown in
In the embodiment of the first block profile 3 shown in
As may be inferred from
In the embodiments according to
In the embodiment of the first block profile 3 shown in
In another embodiment of the first block profile 3, according to the present disclosure, the recesses 38 are designed as double cones in the direction of their longitudinal extension m, the narrowest point having a width h1 and being approximately in the middle in the direction of the longitudinal extension m of the recesses 38. Accordingly, the recess 38 is designed as originating from the recess 33 between the legs 32, the smallest width of this recess 38 in the direction of the longitudinal extension n may be, for example, h2, and the widest point at the entry being h4, the width h4 may, for example, correspond to the equation 1≦h4/h2≦3 having a smallest width h2, which corresponds to the equation 0.1≦h2/h≦0.3.
Finally, in the embodiment according to
As may be inferred from
To further relieve the partition plates and the turbulators, it is within the scope of the present disclosure to produce the first and/or second block profiles 3, 6 from a spring-elastic material.
In the embodiment of the first block profile 3 shown in
In the embodiment according to
In the embodiment of the first block profile 3 shown in
All of the above-mentioned dimensions of the lengths, depths, widths, or diameters of the recesses, depressions, for example, of the first block profiles may be, for example, selected in accordance with the above-mentioned equations. This is to achieve, through the above described possibility for increasing the flexibility or enlarging the heat-transferring area of the first block profiles to the partition plates and the second lamellae 10, a significant stress reduction, for example, on the cyclically stressed components inside the heat exchanger.
Although the present disclosure has been described and illustrated in detail, it is to be clearly understood that this is done by way of illustration and example only and is not to be taken by way of limitation. The scope of the present disclosure is to be limited only by the terms of the appended claims.
Number | Date | Country | Kind |
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202011052186.9 | Dec 2011 | DE | national |