U.S. patent application number 12/813818 was filed with the patent office on 2010-12-23 for heat-exchanging device and motor vehicle.
This patent application is currently assigned to Behr GmbH & Co. KG. Invention is credited to Johannes Diem, Peter Geskes, Jens Holdenried, Klaus Irmler, Martin Kaemmerer, Ulrich Maucher, Eberhard Pantow, Michael Schmidt.
Application Number | 20100319887 12/813818 |
Document ID | / |
Family ID | 40547430 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100319887 |
Kind Code |
A1 |
Diem; Johannes ; et
al. |
December 23, 2010 |
HEAT-EXCHANGING DEVICE AND MOTOR VEHICLE
Abstract
An exhaust gas installation is provided that comprises an
exhaust gas evaporator mounted downstream of an internal combustion
engine of a motor vehicle. The exhaust gas evaporator has a
sandwich-type structure wherein exhaust gas planes and coolant
planes are alternately directly adjacently arranged, providing a
very compact while very efficient exhaust gas evaporator.
Inventors: |
Diem; Johannes; (Weissach,
DE) ; Pantow; Eberhard; (Winnenden, DE) ;
Maucher; Ulrich; (Korntal-Muenchingen, DE) ; Geskes;
Peter; (Ostfildern, DE) ; Kaemmerer; Martin;
(Esslingen, DE) ; Irmler; Klaus; (Tuebingen,
DE) ; Holdenried; Jens; (Ditzingen, DE) ;
Schmidt; Michael; (Bietigheim-Bissingen, DE) |
Correspondence
Address: |
Muncy, Geissler, Olds & Lowe, PLLC
4000 Legato Road, Suite 310
FAIRFAX
VA
22033
US
|
Assignee: |
Behr GmbH & Co. KG
Stuttgart
DE
|
Family ID: |
40547430 |
Appl. No.: |
12/813818 |
Filed: |
June 11, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2008/010662 |
Dec 15, 2008 |
|
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|
12813818 |
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Current U.S.
Class: |
165/148 |
Current CPC
Class: |
F28D 21/0003 20130101;
F28F 3/06 20130101; F01N 2240/02 20130101; F01N 5/02 20130101; F28D
2021/0085 20130101; F28D 9/0031 20130101; F28D 2021/0071
20130101 |
Class at
Publication: |
165/148 |
International
Class: |
F28D 1/00 20060101
F28D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 13, 2007 |
DE |
DE102007060523.6 |
Claims
1. A device for exchanging heat between a first medium and a second
medium, the device comprising: a plurality of plate pairs stacked
one on top of another in a stacking direction; a first flow space
through which a first medium is adapted to flow is arranged between
two plates of at least one plate pair; and a second flow space
through which a second medium is adapted flow is arranged between
two plate pairs adjacent to one another, wherein the first flow
space has a first flow path for the first medium with flow path
sections, in which the first medium is adapted to flow through the
flow path sections one after another in opposite directions, and
which are separated from one another by a partition wall arranged
between the at least two plates of the at least one plate pair.
2. The device according to claim 1, wherein two flow path sections,
which are adapted to be flown through directly one after another,
are connected to one another via a deflection section.
3. The device according to claim 2, wherein the deflection section
is formed by a recess or a break in the partition wall.
4. The device according to claim 2, wherein the deflection section
is formed by a gap remaining between the partition wall and a
lateral boundary of the first flow space or the plate pair.
5. The device according to claim 1, wherein two or more than two
partition walls are formed together as a single piece.
6. The device according to claim 5, wherein the two or more
partition walls are formed by an auxiliary plate arranged between
the at least two plates of the at least one plate pair and formed
as a corrugated sheet.
7. The device according to claim 1, wherein at least one flow path
section has one, two, or more than two flow channels which are
configured to be flown through parallel to one another.
8. The device according to claim 2, wherein at least two of the
flow channels of the at least one flow path section are connectable
to one another via the deflection section.
9. The device according to claim 1, wherein the flow channels are
closed at their front ends by a boundary of the first flow space or
by one or both plates of the plate pair.
10. The device according to claim 1, wherein a first deflection
section is arranged to a second flow channel at a first partition
wall of a first flow channel at a first front end of the first flow
channel, and wherein a second deflection section is arranged to a
third flow channel, which is different from the second flow
channel, at a second partition wall of the first flow channel at a
second front end lying opposite to the first front end of the first
flow channel.
11. The device according to claim 1, wherein the flow channels
together with the deflection channels form a single serpentine-like
meandering flow path through the first flow space.
12. The device according to claim 1, wherein the first and the
second flow space are configured to flown through in different main
flow directions.
13. The device according to claim 1, wherein the second flow space
has a larger flow cross section than a flow path section of the
flow path in the first flow space, particularly a larger flow cross
section than the first flow space.
14. A motor vehicle comprising a combustion engine, an exhaust gas
line, and a device, arranged in the exhaust gas line, for
exchanging heat between a coolant of a cooling circuit of the
combustion engine and the exhaust gas or between a cooling agent of
a cooling circuit of an air conditioning system and the exhaust
gas, wherein the coolant or the cooling agent is evaporated in the
device, and wherein the device comprises: a plurality of plate
pairs stacked one on top of another in a stacking direction; a
first flow space through which a first medium is adapted to flow is
arranged between two plates of at least one plate pair; and a
second flow space through which a second medium is adapted flow is
arranged between two plate pairs adjacent to one another, wherein
the first flow space has a first flow path for the first medium
with flow path sections, in which the first medium is adapted to
flow through the flow path sections one after another in opposite
directions, and which are separated from one another by a partition
wall arranged between the at least two plates of the at least one
plate pair
15. The motor vehicle according to claim 14, wherein the first flow
channels are arranged substantially vertical to a base of the motor
vehicle, the base being a road surface.
16. The motor vehicle according to claim 15, wherein the base of
the motor vehicle is a road surface.
17. The motor vehicle according to claim 14, wherein the first flow
channels are arranged substantially perpendicular to a base of the
motor vehicle.
Description
[0001] This nonprovisional application is a continuation of
International Application No. PCT/EP2008/010662, which was filed on
Dec. 15, 2008, and which claims priority to German Patent
Application No. DE 10 2007 060 523.6, which was filed in Germany on
Dec. 13, 2007, and which are both herein incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a device for exchanging heat and to
a motor vehicle with a device of this type.
[0004] 2. Description of the Background Art
[0005] Thermal energy recovery from exhaust gases of an internal
combustion engine is gaining steadily in importance in the
automotive sector as well. In this regard in particular, thermal
energy recovery by means of an exhaust gas evaporator continues to
be the main focus in order to hereby achieve an increase in
efficiency with respect to the operation of an internal combustion
engine. In an exhaust gas evaporator, heat is removed from the
exhaust gas and supplied to a coolant or cooling agent, which is
typically evaporated in so doing. The thermal energy removed from
the exhaust gas can be used for a downstream Clausius-Rankine
process.
[0006] For example, DE 601 23 987 T2, which corresponds to U.S.
Pat. No. 6,845,618. deals with this topic, in which a Rankine cycle
system is described in relation to an internal combustion engine,
in which a high-temperature and high-pressure vapor can be
generated with use of an evaporator by means of the thermal energy
from an exhaust gas of the internal combustion engine.
SUMMARY OF THE INVENTION
[0007] It is therefore an object of the present invention to
provide a device for exchanging heat in an especially compact and
efficient manner, particularly in regard to use in a motor vehicle.
Accordingly, in an embodiment, one of a participating media is
guided in a serpentine-like manner within one of the stacked layers
in a plate heat exchanger.
[0008] Because the present exhaust gas evaporator is designed with
a so-called sandwich design, in which exhaust gas layers and
coolant layers are arranged alternately directly side-by-side, the
exhaust gas layers can come extensively into contact with the
coolant layers, so that the thermal energy transfer from the
exhaust gases to the coolant can occur especially rapidly and
effectively.
[0009] Based on the large available contact surface areas between
an exhaust gas side and an evaporator side of the exhaust gas
evaporator, it can in addition be made very compact. This is of
particular advantage especially in automotive engineering, because
here components of a motor vehicle are to take up as little space
as possible and at the same time to be made very light. Thus, a
very high-performance construction with respect to the interaction
of the exhaust gas side and the evaporator side of the exhaust gas
evaporator is advantageously provided by the sandwich design.
[0010] According to an embodiment of the present invention, a first
flow space has a first flow path for the first medium with flow
path sections which can be flown through one after the other in
opposite directions. The flow path sections can be separated from
one another by a partition wall arranged between the at least two
plates of the least one plate pair.
[0011] In an embodiment, two flow path sections can be flown
through directly one after another and can be connected to one
another via a deflection section. The deflection section can be
formed by a recess, for example, by an opening in the partition
wall. According to another embodiment, the deflection section can
be formed by a gap remaining between the partition wall and a
lateral boundary of the first flow space, for example, a plate
pair.
[0012] Two or more than two partition walls can be formed together
as a single piece. The two or more partition walls can be formed by
an auxiliary plate arranged between the at least two plates of the
at least one plate pair and formed especially as a corrugated
sheet.
[0013] In an embodiment, at least one flow path section can have
one, two, or more than two flow channels which can be flown through
parallel to one another. At least two of the flow channels of the
at least one flow path section can be connected to one another via
the deflection section. For operation of the device of the
invention, it is possible to set a pressure loss, on the one hand,
and a residence time of the first medium in the first flow space,
on the other, by a predefined number of parallel-connected flow
channels.
[0014] The flow channels can be closed at their front ends by a
boundary of the first flow space or by one or both plates of the
plate pair.
[0015] A first deflection section can be arranged with respect to a
second flow channel at a first partition wall of a first flow
channel at a first front end of the first flow channel and a second
deflection section can be arranged with respect to a third flow
channel, different from the second flow channel at a second
partition wall of the first flow channel at a second front end,
lying opposite to the first front end of the first flow
channel.
[0016] The flow channels together with the deflection channels can
form a single serpentine-like meandering flow path through the
first flow space.
[0017] The first and the second flow space can be flown through in
different main flow directions.
[0018] The second flow space can have a larger flow cross section
than a flow path section of the flow path in the first flow space,
particularly a larger flow cross section than the first flow space.
This type of embodiment is designed particularly for operation with
a liquid, optionally evaporating first medium and a gaseous second
medium.
[0019] The device of the invention can be used in a motor vehicle
with a combustion engine and an exhaust gas line and is used for
exchanging heat between a coolant, particularly of a cooling
circuit of the combustion engine, and the exhaust gas or between a
cooling agent of a cooling circuit of an air conditioning system
and the exhaust gas, whereby the coolant or the cooling agent is
evaporated particularly in the device. The exhaust gas in this case
can be the second medium. In this case, the first flow channels are
arranged essentially vertical, for example, essentially
perpendicular to a base of the motor vehicle.
[0020] The term "exhaust gas system" can be understood here to be
any component through which exhaust gases of an internal combustion
engine are conducted after leaving the internal combustion engine.
The term "exhaust gas system" thus also comprises components of an
exhaust gas recirculation system. In particular, the exhaust gas
evaporator described herein may be integrated into an exhaust gas
recirculation system of this type.
[0021] The term "coolant" can describe any vaporizable working
medium by means of which thermal energy can be taken up in a
sufficient amount and transported. Water in particular, which can
also be present as water vapor, is especially highly suitable for
this purpose.
[0022] The term "sandwich design" is largely self-explanatory, it
being clear, particularly in connection with the exhaust gas
evaporator described herein, that exhaust gas layers are arranged
alternately with coolant layers in or at the exhaust gas
evaporator. The designation "plate design" is also often used for
the term "sandwich design."
[0023] It is therefore also advantageous when on the exhaust gas
side more than one exhaust gas layer and/or on the coolant side
more than one coolant layer are provided, because heat exchange
between the exhaust gas and the coolant can be realized much more
effectively, particularly with several exhaust gas and/or coolant
layers. The coolant layers can be connected parallel in particular,
so that it is assured that all coolant layers can be supplied with
coolant independently of one another. It is also possible, however,
that one or more coolant layers are connected to one another in
series.
[0024] In this case, the exhaust gas layers and the coolant layers
can abut directly with their respective broadsides or the exhaust
gas layers and the coolant layers are arranged separated from one
another only by a highly heat-conducting partitioning device. Each
coolant layer can be enclosed on both sides by an exhaust gas layer
in each case, so that the coolant layers are always warmed or
heated from two sides.
[0025] So that the exhaust gases, on the one hand, in the exhaust
gas layer and the coolant, on the other, in the coolant layer can
be conducted through the exhaust gas evaporator, an embodiment
provides that the exhaust gas evaporator on the exhaust gas side
can have an exhaust gas guiding device and/or on the evaporator
side a coolant guiding device, which are separated spatially from
one another.
[0026] The coolants hereby can be conducted along and in the
coolant layer, when several coolant channels, running parallel to
one another, such as flow channels, are arranged in each coolant
layer. Hereby, especially long, narrow coolant channels can be
provided advantageously, in which the coolant can heat up
rapidly.
[0027] Merely owing to the described sandwich design, in which
exhaust gas layers and coolant layers may be arranged directly
side-by-side, a high performance with respect to the exhaust gas
evaporator can be achieved with only a small space being necessary.
Because in the present case additional exhaust gas channels or
coolant channels can be provided in the individual layers of the
exhaust gas evaporator, a high performance or improvement of
performance can be achieved even with very narrowly predefined
space constraints.
[0028] It is advantageous accordingly when to conduct the exhaust
gases several exhaust gas channels, running parallel to one
another, are arranged in the exhaust gas layer as well. For
example, these exhaust gas channels can run linearly through the
exhaust gas evaporator with respect to their front ends from an
exhaust gas evaporator inlet side to an exhaust gas evaporator
outlet side. The exhaust gas channels are opened in each case at
their front ends, so that the exhaust gases can flow into the
exhaust gas channels via openings in the front ends and flow out
again. In this case, preferably a plurality of exhaust gas channels
are arranged side-by-side in the exhaust gas layer, so that several
exhaust gas channels are arranged between a first side region and a
second side region. Thus, the exhaust gases can be conducted over a
wide area in the plurality of exhaust gas channels in a first main
flow direction through the exhaust gas evaporator.
[0029] The exhaust gas evaporator in this case can be constructed
especially simply, when the coolant channels on the evaporator side
are arranged with a similar or even identical orientation as the
exhaust gas channels on the exhaust gas side.
[0030] However, so that the coolant can take up thermal energy from
the exhaust gases especially effectively, it is advantageous when
the coolant can stay for a sufficiently long time in the exhaust
gas evaporator. On the one hand this can be realized, for example,
in that the coolant passes through the exhaust gas evaporator with
a lower flow velocity. On the other hand, the exhaust gas
evaporator can be made longer. An embodiment provides that the
coolant in the exhaust gas evaporator in a coolant layer can cover
an especially long stretch through the exhaust gas evaporator. Such
a long stretch in a coolant layer can be realized in an especially
simple structural manner when the coolant channels are spatially
connected to one another. By means of the spatial connection, the
coolant can flow from one coolant channel to another coolant
channel and thereby stay for an especially long time in the exhaust
gas evaporator.
[0031] In this example connection, the coolant channels can be
closed at their front ends. As a result, it is not necessary that
openings at the front ends, for example, of two coolant channels
directly next to one another and/or corresponding to one another
must be connected to one another by suitable tubing. Rather,
suitable connecting openings between two coolant channels can be
provided in a common partition wall.
[0032] Thus, an embodiment also provides that a first connecting
opening to a second coolant channel can be arranged on a first
partition wall of a first coolant channel at the first front end of
the first coolant channel and a second connecting opening to
another coolant channel is arranged on a second partition wall of
the first coolant channel at a second front end of the first
coolant channel. As a result, all coolant channels of a coolant
layer can be combined into a meandering coolant stretch. Basically,
such connecting openings can be provided on each partition wall.
Cooling channels can also be connected in parallel, in that the
connecting openings are provided in a suitable manner on the
partition walls and/or at the front ends.
[0033] To be able to provide the longest coolant stretch possible
in one of the coolant layers, it is therefore advantageous when the
coolant channels together form a single meandering coolant stretch
through the exhaust gas evaporator.
[0034] It is advantageous, further, if the exhaust gas evaporator
has a coolant stretch and an exhaust gas stretch, whereby the
coolant stretch is arranged with a different orientation in the
exhaust gas evaporator than the exhaust gas stretch. As a result,
the exhaust gases and the coolant can flow through the exhaust gas
evaporator, for example, in a crossflow. It is clear that the
exhaust gases and the coolant could also flow in a counterflow to
one another in suitably selected channels.
[0035] In this example connection, an object of the invention is
also achieved by a method for operating an internal combustion
engine of a motor vehicle, in which exhaust gases of the internal
combustion engine are conducted by means of an exhaust gas unit
into the environment and thermal energy is removed from the exhaust
gases beforehand by means of vaporizable coolants, and in which the
exhaust gases within an exhaust gas evaporator are conducted in a
first main flow direction and the coolant in a main flow direction
opposite to the first main flow direction through the exhaust gas
evaporator, whereby the coolant is conducted through the exhaust
gas evaporator in sections transverse to the main flow directions.
The exhaust gases and the coolant in this case are moved not only
in counterflow to one another through the exhaust gas evaporator,
but also in crossflow, as a result of which the coolant in
particular remains for an especially long time in the exhaust gas
evaporator and in so doing, can become warmed or heated especially
well.
[0036] In an embodiment, both the exhaust gas channels and the
coolant channels can be arranged differently in the exhaust gas
evaporator. To reduce in particular the risk that a critical
collection of liquid, particularly of water, can occur in one of
the coolant channels, it is advantageous if the coolant channels
are arranged oriented essentially vertical within the exhaust gas
evaporator, particularly essentially vertical to a roadway
surface.
[0037] By means of the connecting openings, which can be arranged
very close to the front end walls, it can be avoided, moreover,
that collection pools for still not evaporated water arise on the
bottom side of a coolant layer. In this way, the risk of a decline
in performance of the exhaust gas evaporator, based on such water
collection sites, are avoided. In an especially advantageous
embodiment variant in this regard, it can be provided that in
addition to the connecting openings also especially an inlet
opening of the coolant layers is placed on the bottom side, so that
it can be reliably assured that the coolant channels of a coolant
layer can be initially supplied with coolant, particularly with
water. In other words, before startup of an internal combustion
engine coolant is ideally available in all coolant channels of the
exhaust gas evaporator, so that uniform evaporation of the coolant
in the coolant layers can be assured.
[0038] As long as a critical water accumulation in one of the
coolant channels or one of the coolant layers can be avoided, it is
also possible to provide the coolant channels or the coolant layers
deflected from a vertical orientation in the exhaust gas
evaporator. A noncritical inclination angle of the exhaust gas
evaporator to be set accordingly that still avoids the situation in
which, for instance, an edge coolant channel and/or an edge coolant
layer is critically flooded with water, but an opposite edge
coolant channel and/or an opposite edge coolant layer is not, can
be reduced as a precaution by more than 5.degree., ideally by about
10.degree., so that unfavorable inclined positions, for example,
based on an inclined mounting of an internal combustion engine, an
exhaust gas unit in a motor vehicle, and/or an unfavorable inclined
position of the motor vehicle per se, can be prevented.
[0039] The supplementary term "edge" can include coolant channels
and/or coolant layers which are arranged outward on the exhaust gas
evaporator compared with the other coolant channels or coolant
layers.
[0040] The previously mentioned inclination angle can be measured
from a vertical plane.
[0041] Thus, it can be especially assured that initially all
coolant channels are supplied with a liquid coolant or with water.
This reduces the risk that, for example, a coolant channel
initially not supplied with water conveys the evaporating water
alone.
[0042] The channels of the exhaust gas evaporator can be made and
designed variously. For example, the coolant channels can be made
as tube bundles or with a plate design with separating webs. The
exhaust gas evaporator is especially simple to manufacture in terms
of construction, if coolant channels of a coolant layer are formed
by a corrugated sheet folded multiple times in a plane.
[0043] This type of corrugated sheet can form the channels
described herein, for example, in conjunction with separating webs
arranged parallel to the present layers, whereby the exhaust gas
channels can also be realized especially simply by means of
separating webs arranged on this type of corrugated sheet.
[0044] In order to have the least possible flow losses within the
channels, smooth channel walls can be provided in another
embodiment. In particular, the dimensions of the cooling channels
can be shaped almost without limitation by variously selected
dimensioning of the channel side walls or the channel bottom
walls.
[0045] For example, a change in the channel width can entail a
pressure loss and/or a change in the thermal energy transfer
surface area. The width of the channels as well can affect the
number of channels in an exhaust gas evaporator and/or the total
distance of a coolant stretch of a coolant layer.
[0046] The exhaust gas guiding device and the coolant guiding
device can also be formed variously in terms of construction. The
thermal energy can pass into the coolant especially well from the
hot exhaust gases, if the exhaust gas guiding device is formed in
an exhaust gas layer in the parallel flow and the coolant guiding
device in a coolant layer in the serpentine flow. Because the flow
in the exhaust gas guiding device is parallel, the exhaust gases
can pass the exhaust gas evaporator, for example, with a higher
velocity and noncritical back pressure, whereas the coolant because
of the serpentine flow can stay for a sufficiently long time in the
exhaust gas evaporator, so that it can take up the thermal energy
especially effectively.
[0047] It can be understood that depending on the application other
advantageous designs can be used for the present exhaust gas
evaporator. The flow guidance in the exhaust gas evaporators in
particular can be a decisive criterion for an especially high
efficiency. Moreover, the strength of an exhaust gas evaporator can
be substantially affected with appropriately rigid channels.
[0048] The efficiency in this case can proceed in two optimization
directions. On the one hand, one wishes to achieve minimal pressure
loss in that no deflections or internal structures are present
within a stretch. On the other hand, the largest possible surface
area is to be available for thermal energy transfer. It should be
noted in addition for the pressure loss that the working medium
greatly reduces its density with the change of the physical state,
particularly from liquid to gaseous, and this can multiply the flow
velocity. A specific optimum must be found therefore between
pressure loss and heat output.
[0049] Particularly, in exhaust gas evaporators, the strength, as
already mentioned above, is another important topic, because the
working medium, particularly a coolant, usually should be operated
at working pressures above ambient pressure, in order to achieve a
sufficiently good effectiveness in association with the exhaust gas
evaporator. Therefore, the selected geometries of the employed
components must also be able to easily absorb the compressive
forces possibly arising because of the occurring working pressures.
Thermal stresses, possibly caused by the temperature differences
between the two working media, therefore the exhaust gases, on the
one hand, and the coolant, on the other, must also be able to be
absorbed. The selected sheet thickness of a corrugated sheet also
has a direct effect on the strength, particularly when individual
sheet regions of the exhaust gas evaporator are used as tie rods.
Further, the sheet thickness may have an effect on the thermal
conductivity.
[0050] Another possibility of increasing efficiency is to provide
turbulence-generating structures in the channels. This can be
easily assured by the previously described structure of the present
exhaust gas evaporator, particularly in view of a corrugated sheet
folded multiply in a plane.
[0051] The exhaust gas evaporator described here can be used
advantageously in almost all motor vehicles, particularly also in
commercial vehicles.
[0052] 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
[0053] 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:
[0054] FIG. 1 shows schematically a view of a motor vehicle with an
internal combustion engine and an exhaust gas unit with an exhaust
gas evaporator;
[0055] FIG. 2 schematically shows a perspective view of the exhaust
gas evaporator of FIG. 1;
[0056] FIG. 3 schematically shows a partially cutaway view of the
exhaust gas evaporator of FIGS. 1 and 2;
[0057] FIG. 4 schematically shows a perspective view of a
corrugated sheet of the exhaust gas evaporator in FIGS. 1 to 3 for
realizing a first coolant layer; and
[0058] FIG. 5 shows a perspective view of an alternative corrugated
sheet.
DETAILED DESCRIPTION
[0059] The motor vehicle 1 shown in FIG. 1 comprises an internal
combustion engine 2 with a downstream exhaust gas unit 3, in which
in this exemplary embodiment an exhaust gas evaporator 5, a
catalyst 6, a central silencer 7, and a rear silencer 8 are
arranged in an exhaust gas line 4. Vehicle 1 stands with four
wheels 9 (identified here only by way of example) on a road base
10, which lies in the plane of the paper according to the
illustration in FIG. 1.
[0060] Exhaust gas evaporator 5 is shown in detail schematically in
FIGS. 2 to 4, whereby particularly in FIG. 2 the sandwich design 11
of exhaust gas evaporator 5 can be clearly seen with its many
exhaust gas layers 12 (identified here only by way of example) and
with its many coolant layers 13 (also identified here only by way
of example). Exhaust gas layers 12 are hereby formed somewhat
thicker with respect to their thickness 14 than the narrower
coolant layers 13, so that exhaust gases can pass through exhaust
gas layers 12 more rapidly. Advantageously, in the sandwich design
11, selected here, the two outer layers are exhaust gas layers 12,
so that it is assured that all coolant layers 13 are surrounded on
both sides by exhaust gas layers 12. As a result, the coolant in
coolant layers 13 can be heated especially rapidly.
[0061] Both coolant layers 13 and exhaust gas layers 12 are
arranged in a vertical orientation 15 in exhaust gas evaporator 5,
whereby the bottom side 16 of exhaust gas evaporator 5 faces the
road base 10. According to the sandwich design 11 of the present
exhaust gas evaporator 5, a coolant layer 13 follows an exhaust gas
layer 12.
[0062] The coolant, which in this exemplary embodiment is water or
in the heated state water vapor 17 (see FIG. 3), reaches a coolant
channel 19 via an inlet opening 18 (see FIG. 4) according to a main
flow direction 20. The coolant meanders in coolant layers 13
through exhaust gas evaporator 5 and hereby takes up more and more
thermal energy from the exhaust gases, which flow essentially
linearly through exhaust gas layers 12 according to the main flow
direction 21.
[0063] Whereas the coolant flows along a coolant stretch 22
meandering through coolant layer 13, it reaches in each case other
coolant channels 25 (identified here only by way of example) of
coolant layers 13 via connecting openings 23 (identified here only
by way of example) through individual partition walls 24
(identified here only by way of example) and thus snakes along the
main flow direction 20. All coolant channels 19 and 25 are
essentially parallel to one another and arranged essentially in the
vertical orientation 15 in the respective coolant layer 13. In this
regard, cooling channels 19 and/or 25 are flown through either in a
first side flow direction 26 or in a second side flow direction 27,
which run transverse to the two main flow directions 20 and 21.
[0064] A coolant guiding device 28, as it can provide several
cooling channels 19 and/or 25 in one of the coolant layers 13 of
exhaust gas evaporator 5, can include a corrugated sheet 29 with a
flat fin geometry 30. By means of corrugated sheet 29, the coolant
guiding device 28 is provided especially simply in terms of
construction. It is understood that depending on how the flat fin
geometry 30 is selected with respect to a fin width 31 and/or a fin
height 32, the total length of the coolant stretch 22 and the
number the coolant channels 19, 25 can be varied. In this case, the
fin height 32 determines in particular the coolant channel height
and the fin width 31 the coolant channel width, both of which are
not explicitly illustrated, because they result essentially from
the fin height 32 or the fin width 31.
[0065] Coolant channels 19, 25 are closed at their front ends 33,
33A (not shown here, but identified by way of example), so that the
coolant can flow only via connecting openings 23 from a coolant
channel 19 into the other coolant channels 25, until the coolant
again leaves coolant layer 13 via an outlet opening 34 of the
coolant guiding device 28. Thus, by means of connecting openings
23, a deflection of the coolant is achieved along the coolant
stretch 22 within coolant layer 13.
[0066] In the specific exemplary embodiment according to FIG. 4,
therefore a first connecting opening 23A to a second coolant
channel 19B is arranged at a first partition wall 24A of a first
coolant channel 19A at the first front end 33 of the first coolant
channel 19A and a second connecting opening 23B to another coolant
channel 19C is arranged at a second partition wall 24B of the first
coolant channel 19A at a second front end 33A of the first coolant
channel 19A.
[0067] An exhaust gas guiding device is not shown in the present
case, because it essentially has structurally linearly formed
exhaust gas channels, whose front ends are not closed, so that the
exhaust gases can flow over them into the exhaust gas channels and
also flow out again of the exhaust gas channels. The exhaust gas
guiding device can also be made of a corrugated sheet, but without
the previously described connecting openings 23. Because several
exhaust gas channels are connected parallel to the exhaust gas
guiding device, the exhaust gas guiding device in this exemplary
embodiment is designed as multiflow. In contrast to this, coolant
channels 19, 25 are connected in series to coolant guiding device
28, because the coolant flows sequentially through all coolant
channels 19, 25. Thus, coolant guiding device 28 is constructed as
single-flow in this exemplary embodiment.
[0068] A partition base (not shown here) is arranged between the
exhaust gas guiding device and coolant guiding device 28, to
separate spatially in this way the specific exhaust gas layers 12
and coolant layer 13, particularly the exhaust gas channels and the
coolant channels 19, 25, from one another. In particular, based on
the combination selected here of the present corrugated sheet 29,
the partition base, and the closed front ends 33, 33A, exhaust gas
evaporator 5 gains a very high strength in an especially
advantageous manner in connection with the sandwich design 11.
[0069] It is understood that the described exhaust gas evaporator 5
represents only a first exemplary embodiment, but is not to be
understood as limiting with respect to the invention.
[0070] FIG. 5 shows an additional plate made as a corrugated sheet
41, which is used in a device, not shown further, for the exchange
of heat according to the present invention. Corrugated sheet 41 has
partition walls 42, 42a, which are formed as a single piece with
one another and separate flow channels 43, 44, 45, 46, 47, 48, 49,
50 from each other. In this case, flow channels 43 and 45 form a
first flow path section, flow channels 44 and 46 a second flow path
section, flow channels 47 and 49 a third flow path section, and
flow channels 48 and 50 a fourth flow path section.
[0071] The first and third flow path sections in this case are
flown through, for example, toward the viewer, whereas the second
and the fourth flow path section are flown through away from the
viewer. The first flow path section 43, 45 in this case is
connected with the second flow path section 44, 46 via a deflection
section formed by a recess 51. The second flow path section 44, 46
is connected with the third flow path section 47, 49 via a
deflection section, which is not shown. The third flow path section
47, 49 is connected in turn with the fourth flow path section 48,
50 via a deflection section formed by a recess 52. Gaps forming the
deflection sections result, due to recesses 51, 52, between
partition walls 42 and a side wall of the first flow space in which
corrugated sheet 51 is arranged, said side wall which is not shown
and closes the flow channels on its front end facing the
viewer.
[0072] Partition walls 42a, in contrast, are connected to the side
wall, so that the flow path sections are flown through in the
mentioned sequence and alternately in the opposite flow directions.
Thus, a single serpentine-like meandering flow path through the
first flow space, which is formed by the series connection of the
flow path sections, forms for the first medium.
[0073] The object of the invention is achieved in particular also
by an exhaust gas unit with an exhaust gas evaporator, which is
mounted downstream of an internal combustion engine of a motor
vehicle, whereby the exhaust gas evaporator has a sandwich design,
in which exhaust gas layers and coolant layers are arranged
alternately directly side-by-side, whereby the exhaust gas
evaporator preferably has an exhaust gas guiding device on the
exhaust gas side and a coolant guiding device on the evaporator
side, which are separated spatially from one another, whereby
preferably in each of the coolant layers several coolant channels
running parallel to one another are arranged, which are connected
particularly spatially one below the other, whereby the coolant
channels are preferably closed at their front ends.
[0074] Preferably, a first connecting opening to a second coolant
channel is arranged on a first partition wall of a first coolant
channel at a first front end of the first coolant channel and a
second connecting opening to another coolant channel is arranged on
a second partition wall of the first coolant channel at a second
front end of the first coolant channel, whereby the coolant
channels preferably together form a single meandering coolant
stretch through the exhaust gas evaporator and/or are arranged
essentially oriented vertically within the exhaust gas evaporator,
particularly essentially vertical to a road surface, whereby the
exhaust gas evaporator preferably has a coolant stretch and an
exhaust gas stretch, whereby the coolant stretch is arranged with a
different orientation in the exhaust gas evaporator than the
exhaust gas stretch.
[0075] Preferably, coolant channels of a coolant layer are formed
by means of a corrugated sheet, folded multiply in the coolant
layer, and/or the exhaust gas guiding device is formed as multiflow
and the coolant guiding device as single-flow.
[0076] The object of the invention is achieved in particular also
by a method for operating an internal combustion engine of a motor
vehicle, in which exhaust gases of the internal combustion engine
are conducted by means of an exhaust gas unit into the environment
and thermal energy is removed from the exhaust gases beforehand by
means of vaporizable coolants, whereby the exhaust gases within an
exhaust gas evaporator are conducted in a first main flow direction
and the coolants in a main flow direction opposite to the first
main flow direction through the exhaust gas evaporator, whereby the
coolants are conducted through the exhaust gas evaporator
transverse to the main flow directions in sections.
[0077] 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.
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