US20180058765A1

US20180058765A1 - Heat exchanger

Info

Publication number: US20180058765A1
Application number: US15/679,504
Authority: US
Inventors: Vladimir PARFENOV
Original assignee: Autokuehler GmbH and Co KG; AKG Thermotechnik International GmbH and Co KG
Current assignee: Autokuehler GmbH and Co KG
Priority date: 2016-08-26
Filing date: 2017-08-17
Publication date: 2018-03-01
Also published as: DE102017119119A1; DE202016104702U1

Abstract

A heat exchanger includes a heat exchanger block, a first collector box arranged on a first end face of the heat exchanger block and a second collector box arranged on a second end face of the heat exchanger block opposite to the first end face of the heat exchanger block. The heat exchanger block has multiple process channels arranged parallel to one another and connecting the first collector box to the second collector box for the through flow of a process medium, and also multiple coolant medium channels for the through flow of a coolant medium. The coolant medium channels are arranged between the process channels. Adjacent process channels have different material masses, heat-transferring areas of different sizes, and/or structural flow resistances of different sizes, and/or coolant medium channels have different material masses and/or heat-transferring areas of different sizes, so that in operation, in the event of a cyclic temperature change of the process medium, an equal or nearly equal material temperature gradient results between adjacent process channels and lateral parts in the heat exchanger block.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to German patent application DE 20 2016 104 702.1, filed Aug. 26, 2016, the entire disclosure of which is herein expressly incorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

Exemplary embodiment of the present invention relate to a heat exchanger.
Heat exchangers used for high-temperature applications, for example, in charge air coolers, radiators, and oil coolers of motor vehicles and construction machines, are subjected to substantial cyclic thermal tensions as a result of cyclic changes of the temperature and flow rate of process media guided through the heat exchanger.
The cyclic change of temperature and flow rate of the process medium correspondingly results in a cyclic change of the temperature of the individual components of the heat exchanger, in particular the components of a heat exchanger block, which consists of process channels, coolant medium channels, end plates, lateral parts, and the like, and the collector boxes adjoining thereon, and a cyclically occurring material expansion or compression of the various heat exchanger components which accompanies this.
These components are fixedly connected to one another by soldering or in another manner to form a rigid block, so that high thermal tensions occur in and between the individual components, which has a negative effect on the service life of the radiator.
To lengthen the service life of such a heat exchanger, it is important to reduce the occurring thermal tensions as a result of the above-described cyclic thermal expansions, primarily in the block length and block width directions.
A reduction of the thermal tensions can be achieved by the use of flexible components in the heat exchanger block. Such heat exchangers are known, for example, from German patent documents DE 202 08 748 U1 and 20 2011 052 186 U1, in which flexible block profiles are used in an edge region of the heat exchanger block, adjoining a collector box, which hold the process channels of the heat exchanger block arranged parallel to one another spaced apart and form the flow channels of the coolant medium together with the fins arranged between the process channels.
These heat exchangers achieve a reduction of the tensions induced by cyclic thermal expansions in the block width direction of approximately 50% compared to heat exchangers having nonflexible block profiles.
However, it has been shown that the maximum tensions occurring in the block longitudinal direction are reduced only slightly in spite of the flexibly designed block profile.
To reduce the maximum tensions in edge-side process channels of a heat exchanger block, in particular in the block length direction, providing slots in end or terminal plates of the heat exchanger block, which close the heat exchanger block on an upper side and a lower side, is known from European patent document EP 0 748 995 B1. The tension in the edge process channels is only reducible by 1.1 to 1.3 times in this way, however.
For stiffening the edge process channels in the block length direction, manufacturing them from thicker partition plates than the further partition plates used in the interior of the heat exchanger block is also known. However, the maximum material temperature difference between the edge process channels and the process channels arranged adjacent thereto further into the interior of the heat exchanger block does not thus change. A further tension reduction is therefore not achievable by this measure.
The maximum material temperature difference between two adjoining process channels can reach up to 20 K or even up to 40 K in running operation in critical block regions in the heat exchangers considered here.
Exemplary embodiments of the present invention are directed to a heat exchanger having lengthened service life and lower risk of cracks.
A heat exchanger according to the invention has a heat exchanger block, a first collector box, which is arranged on a first end face of the heat exchanger block, and a second collector box, which is arranged on a second end face of the heat exchanger block opposite to the first end face of the heat exchanger block.
The heat exchanger block has multiple process channels, which are arranged in parallel to one another and connect the first collector box to the second collector box, for through flow of a process medium, and also multiple coolant medium channels for through flow of a coolant medium, wherein the coolant medium channels are arranged between the process channels, wherein adjacent process channels are formed having different material masses and/or heat-transferring areas of different sizes and/or structural flow resistances of different sizes and/or coolant medium channels are formed having different material masses and/or heat-transferring areas of different sizes, so that in operation, in the event of a cyclic temperature change of the process medium, an equal or nearly equal material temperature gradient results between adjacent process channels and lateral parts in the heat exchanger block.
Due to the combinations of different material masses, heat-transferring areas, and/or structural flow resistances, the process channels, coolant medium channels, and lateral parts are formed so that an equal or nearly equal cyclic change of the material temperatures of adjacent process channels is reached, whereby the maximum temperature difference between the process channels, in particular in the critical block regions, is reduced by at least two or three times in relation to the construction of heat exchangers known from the prior art.
A reduction of the thermally-related tensions in the heat exchanger block by up to two times is thus enabled in the block length direction.
According to one preferred embodiment variant, the process channels having higher heat-transfer rate than the process channels adjoining them are formed having an up to three times greater material mass and/or having an up to three times smaller heat-transferring area and/or having an up to five times greater structural flow resistance than the adjoining process channels.
Such different material masses are achieved, for example, by the use of similar passage components such as partition plates, turbulators, or longitudinal profiles having different structural dimensions and also optional additional components, for example, intermediate profiles or the use of pipes having different pipe dimensions, for example, different pipe thicknesses or pipe heights in one process channel in relation to two adjoining process channels.
A reduction of the maximum difference between the material temperatures of adjacent process channels in the event of a thermal cyclic stress by up to 2.5 times is thus enabled.
According to a further preferred embodiment variant, the process channels adjoining a process channel having a higher heat transfer rate than the process channels adjacent thereto are formed having an up to three times smaller heat-transferring area than the adjacent, adjoining process channels in the heat exchanger block.
Such a heat-transferring area, which is up to three times smaller, can be achieved, for example, by corresponding different structural dimensions, in particular lobe parts of the turbulators or different rib divisions.
Heat transfers of different sizes from the process medium to the coolant medium channels thus occur in adjacent process channels, which has the result that the maximum difference between the cyclic material temperatures of the adjoining process channels is reduced in the event of a thermal cyclic stress.
According to a further preferred embodiment variant, the coolant medium channels adjoining a process channel having a higher heat transfer are formed having an up to three times smaller heat-transferring area.
The reduction of the heat-transferring area in the above-mentioned coolant medium channels is achieved, for example, by up to three times reduction of the height of the coolant medium channels and/or the use of fins or guide plates in the coolant medium channels having an up to five times greater fin lobe or guide plate division.
The difference between the heat transfers in two adjoining process channels is thus reduced, which has the result that the maximum difference between the cyclic material temperatures of the adjoining process channels is reduced by up to two times.
According to still another preferred embodiment variant, the process channels enabling a higher heat transfer than the adjoining process channels are formed having up to five times higher structural flow resistances for process medium in comparison to these above-mentioned adjoining process channels.
This is achieved, for example, by the use of the different turbulators, longitudinal profiles, or additional components, for example, intermediate profiles, and also pipes having a smaller flow cross section for the flow of the process medium.
A ratio is thus increased between the flow rates of the process medium in the adjoining process channels. As a result, the maximum difference between the cyclic material temperatures in the adjoining process channels is decreased by up to three times, which results in a substantial reduction of the thermal tensions.
According to still another preferred embodiment variant, the end plates/lateral parts are formed having an up to five times smaller material mass than the material mass of the edge process channels. The negative influence of the end plate/lateral part on the cyclic change of the material temperature of the edge process channels is thus reduced, which results in a reduction of the maximum material temperature difference between the edge process channels and adjoining process channels in the heat exchanger block.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Exemplary embodiments of the invention will be explained in greater detail hereafter on the basis of the appended drawings.

In the figures:

FIG. 1 shows a schematic perspective view of one embodiment variant of a heat exchanger according to the invention,

FIG. 2 shows a sectional view A-A of the heat exchanger from FIG. 1 transversely to the flow direction of the process medium with process channels having rectangular channel cross section,

FIG. 3 shows a sectional view A-A of the heat exchanger from FIG. 1 transversely to the flow direction of the process medium with process channels having oval channel cross section,

FIG. 4 shows a sectional view A-A of the heat exchanger from FIG. 1 transversely to the flow direction of the process medium with process channels having circular channel cross section,

FIG. 5 shows a sectional view of the heat exchanger from FIG. 2 along a line B-B, parallel to the flow direction of the process medium,

FIG. 6 shows a sectional view of the heat exchanger from FIG. 3 along a line C-C parallel to the flow direction of the process medium,

FIG. 7 shows a sectional view of the heat exchanger from FIG. 4 along a line D-D parallel to the flow direction of the process medium.

DETAILED DESCRIPTION

In the following description of the figures, terms such as above, below, left, right, front, rear, etc. relate exclusively to the illustration and position selected by way of example in the respective figures of the heat exchanger, the process channels, coolant medium channels, lateral parts, and the like. These terms are not to be understood as restrictive, this means that these references can change due to different operating positions or mirror-symmetrical design or the like.
In FIG. 1, a heat exchanger block is identified as a whole with the reference sign 1. The heat exchanger block 1 has multiple separate process channels 2 arranged parallel to one another, which are used for the through flow of a process medium in a direction X from an entry box 3, which is arranged on a first end face of the heat exchanger block 1, to an exit box 4, which is arranged on a second end face of the heat exchanger block 1. The process channels 2 protrude in this case with respective open ends into the entry box 3 and the exit box 4.
The heat exchanger block 1 furthermore has multiple coolant medium channels 5 for the through flow of a coolant medium. The coolant medium channels 5 are arranged between inner process channels 2 and between edge process channels 6 arranged on an outer edge of the heat exchanger block 1 and also lateral parts 7, preferably embodied as end plates, in the heat exchanger block 1.
The coolant medium channels 5 are arranged in the heat exchanger block 1 so that a through flow of the coolant medium between the process channels 2 occurs in a transverse direction or a direction parallel to the directional flow Y of the process medium.
As is further illustrated in FIG. 1, an inlet nozzle 8 is provided on a head side of the entry box 3, through which the process medium can be supplied into the entry box 3.
An outlet nozzle 9 is accordingly provided on a head side of the exit box 4, through which the process medium can be guided out of the exit box 4.
The inlet nozzle 8 and the outlet nozzle can also be arranged on one of the other sides of the entry box 3 or exit box 4, respectively.
The inlet nozzle 8 and outlet nozzle 9 are accommodated in this case in a receptacle opening, which corresponds to the cross section of the inlet nozzle 8 or the outlet nozzle 9, respectively, in the head side of the entry box 3 or the exit box 4, respectively.
As shown in FIGS. 2 to 4, the process channels 2 can be formed having different cross sections. The process channels 2 in the embodiment variant shown in FIG. 2 are thus formed from respective partition plates 10, between which turbulators 12 or ribs are arranged. A lateral closure of these process channels 2 is achieved here by the use of strips or longitudinal profiles 11.
In the embodiment variant shown in FIG. 3, the process channels 2 are formed as pipes 13 formed having oval channel cross section. Turbulators 12 are inserted into the pipe interior of these pipes 13 in the embodiment variant shown here.
In the embodiment variant shown in FIG. 4, the process channels 2 are formed in the form of pipes having circular cross section. As also in the embodiment variant shown in FIG. 3, multiple such process channels 2 are arranged here perpendicularly to the through flow direction of adjacent to one another and one on top of another.
As can furthermore be seen in FIG. 4, the process channels arranged on an outer edge of the heat exchanger block 1 are provided with the reference sign 6, while the process channels enclosed by the edge process channels 6 are provided with the reference sign 13.
FIGS. 5 to 7 show that the coolant medium channels 5 are also preferably provided with fins 15 or guide plates 16.
For all embodiment variants shown in FIGS. 2-7, adjacent process channels 2, 6 and coolant medium channels 5 are formed having different material masses and/or heat-transferring areas of different sizes and/or structural flow resistances of different sizes, so that in operation, a temperature change of the process medium results in an equal or nearly equal material temperature gradient between adjacent process channels 2, 6 and lateral parts 7 in the heat exchanger block 1, whereby the maximum temperature difference between individual adjacent process channels is reduced by at least 2 to 3 times in relation to heat exchanger blocks known from the prior art.
Thus, according to one embodiment variant of a heat exchanger according to the invention, the material mass of process channels 2, 6 having higher heat transfer rate than the process channels 2, 6 adjoining them is formed having an up to three times greater material mass than these adjoining process channels.
Alternatively or additionally, the heat-transferring area of the process channels 2, 6 having higher heat transfer rate than the process channels 2, 6 adjoining them is up to three times smaller than the heat-transferring area of adjoining process channels 2, 6. This is achieved, for example, by enlarging the lobe division of turbulators or the use of fewer heat-transferring ribs 14 in the process channels 2, 6, into which the hottest component of process medium flows, in relation to the process channels through which a component of the process medium flows which is already partially cooled.
Alternatively or additionally, respective coolant medium channels 5, which adjoin a process channel 2, 6 having a higher heat transfer rate than the process channels 2, 6 adjacent to them, are formed having an up to three times smaller heat-transferring area than adjacent coolant medium channels 5 in the heat exchanger block 1.
Thus, in particular the coolant medium channels 5 between edge process channels 6 and lateral parts 7 are formed having an up to three times smaller heat-transferring area than other coolant medium channels 5 in the heat exchanger block 1.
Furthermore, the lateral parts 7 are preferably formed having an up to five times smaller material mass than the material mass of the edge process channels 6.
In each case, due to the formation of the process channels and coolant medium channels having different material masses or heat-transferring areas of different sizes, the material temperature gradient between adjacent process channels 2, 6 and lateral parts 7 in the heat exchanger block 1 upon the through flow of the process channels with the process medium and the through flow of the coolant medium channels with a coolant medium can be kept constant or nearly constant and as small as possible, whereby thermally-related tensions in the heat exchanger block are significantly reduced and therefore the service life of such heat exchangers is lengthened.
Although the invention has been illustrated and described in detail by way of preferred embodiments, the invention is not limited by the examples disclosed, and other variations can be derived from these by the person skilled in the art without leaving the scope of the invention. It is therefore clear that there is a plurality of possible variations. It is also clear that embodiments stated by way of example are only really examples that are not to be seen as limiting the scope, application possibilities or configuration of the invention in any way. In fact, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete manner, wherein, with the knowledge of the disclosed inventive concept, the person skilled in the art is able to undertake various changes, for example, with regard to the functioning or arrangement of individual elements stated in an exemplary embodiment without leaving the scope of the invention, which is defined by the claims and their legal equivalents, such as further explanations in the description.

LIST OF REFERENCE SIGNS

1 heat exchanger block
2 process channels
3 entry box
4 exit box
5 coolant medium channels
6 edge process channels
7 end plates/lateral parts
8 inlet nozzle
9 outlet nozzle
10 partition plates
11 longitudinal profiles
12 turbulators
13 pipes
14 ribs
15 fins
16 guide plates
L length of the heat exchanger block
B width of the heat exchanger block
T depth of the heat exchanger block
X through flow direction of the process medium to be cooled
Y through flow direction of the coolant medium

Claims

1. A heat exchanger, comprising:

a heat exchanger block;

a first collector box arranged on a first end face of the heat exchanger block;

a second collector box arranged on a second end face of the heat exchanger block opposite to the first end face of the heat exchanger block;

wherein the heat exchanger block has a plurality of process channels arranged parallel to one another and connecting the first collector box to the second collector box for through flow of a process medium,

wherein the heat exchange block has a plurality of coolant medium channels for through flow of a coolant medium,

wherein the plurality of coolant medium channels are arranged between the plurality of process channels,

wherein adjacent process channels of the plurality of process channels have different material masses, heat-transferring areas of different sizes, or structural flow resistances of different sizes, or the plurality of coolant medium channels have different material masses, or heat-transferring areas of different sizes, so that in operation, in event of a cyclic temperature change of the process medium, an equal or nearly equal material temperature gradient results between adjacent process channels and lateral parts in the heat exchanger block.

2. The heat exchanger of claim 1, wherein process channels of the plurality of process channels having higher heat transfer rate than process channels of the plurality of process channel adjoining them have an up to three times greater material mass, an up to three times smaller heat-transferring area, or an up to five times greater structural flow resistance than the adjoining process channels.

3. The heat exchanger of claim 1, wherein the plurality of coolant medium channels adjoining a process channel of the plurality of process channels having a higher heat transfer rate than the process channels of the plurality of process channels adjacent thereto have an up to three times smaller heat-transferring area than other coolant medium channels in the heat exchanger block.

4. The heat exchanger of claim 1, wherein coolant medium channels of the plurality of coolant medium channels and which are between edge process channels and lateral parts have an up to three times smaller heat-transferring area than other coolant medium channels of the plurality of coolant medium channels in the heat exchanger block.

5. The heat exchanger of claim 4, wherein the lateral parts have an up to five times smaller material mass than a material mass of the edge process channels.