U.S. patent application number 16/190902 was filed with the patent office on 2020-05-14 for system for separating liquid exhaust reductant from a mixing conduit wall using flow separation elements.
The applicant listed for this patent is CNH Industrial America LLC. Invention is credited to Hesam Abbassi, Kaushal Ghorpade, Samrendra K. Singh, Panos Tamamidis.
Application Number | 20200149455 16/190902 |
Document ID | / |
Family ID | 70551145 |
Filed Date | 2020-05-14 |
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United States Patent
Application |
20200149455 |
Kind Code |
A1 |
Ghorpade; Kaushal ; et
al. |
May 14, 2020 |
SYSTEM FOR SEPARATING LIQUID EXHAUST REDUCTANT FROM A MIXING
CONDUIT WALL USING FLOW SEPARATION ELEMENTS
Abstract
An exhaust treatment system for a work vehicle includes a
reductant injector configured to inject an exhaust reductant into
the engine exhaust flow flowing through a mixing conduit. A
plurality of flow separation elements are located downstream of the
reductant injector and are configured to separate a liquid
reductant flow from an inner conduit wall of the mixing conduit for
mixing with the engine exhaust flow flowing therein.
Inventors: |
Ghorpade; Kaushal; (Chicago,
IL) ; Tamamidis; Panos; (Northbrook, IL) ;
Singh; Samrendra K.; (Bolingbrook, IL) ; Abbassi;
Hesam; (Birmingham, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CNH Industrial America LLC |
New Holland |
PA |
US |
|
|
Family ID: |
70551145 |
Appl. No.: |
16/190902 |
Filed: |
November 14, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 3/2066 20130101;
F01N 2240/20 20130101; F01N 3/2892 20130101; F01N 2610/1453
20130101; F01N 2610/02 20130101; B01F 5/0473 20130101; B01D 53/9431
20130101; F01N 2590/08 20130101; F01N 3/206 20130101; F01N 2470/30
20130101 |
International
Class: |
F01N 3/28 20060101
F01N003/28; F01N 3/20 20060101 F01N003/20 |
Claims
1. An exhaust treatment system for a work vehicle, the system
rising: an exhaust conduit configured to receive an engine exhaust
flow; a reductant injector configured to inject an exhaust
reductant into the engine exhaust flow; a mixing conduit extending
lengthwise between an upstream end and a downstream end, the mixing
conduit including an inner conduit wall defining a flow area
through which the engine exhaust flow and the exhaust reductant
injected are directed between the upstream and downstream ends of
the mixing conduit to allow the exhaust reductant to be at least
partially mixed into the engine exhaust flow, a portion of the
exhaust reductant flowing along the inner conduit wall of the
mixing conduit as a liquid reductant flow; and a plurality of flow
separation elements provided in operative association with the
inner conduit wall of the mixing conduit, the plurality of flow
separation elements configured to separate the liquid reductant
flow from the inner conduit wall as the liquid reductant flow is
directed across the plurality of flow separation elements.
2. The system of claim 1, wherein the liquid reductant flow is
initiated along the inner conduit wall at a location at or
downstream of a reductant attachment location disposed between the
upstream and downstream ends of the mixing conduit, the plurality
flow separation elements being positioned within the mixing conduit
downstream of the reductant attachment location.
3. The system of claim 1, further comprising a mixer positioned
within the mixing conduit between the upstream end of the mixing
conduit and the plurality of flow separation elements.
4. The system of claim 1, wherein the plurality of flow separation
elements comprise a plurality of radially inwardly extending
protrusions.
5. The system of claim 1, wherein the plurality of flow separation
elements comprise a plurality of radially outwardly extending
indentions formed in the inner conduit wall.
6. The system of claim 1, wherein the plurality of flow separation
elements are disposed in an annular array around the inner conduit
wall of the mixing conduit.
7. The system of claim 1, wherein the plurality of flow separation
elements are circumferentially offset from one another.
8. The system of claim 1, wherein the plurality of flow separation
elements are axially staggered relative to one another along a
length of the mixing conduit.
9. The system of claim 1, wherein the plurality of flow separation
elements are axially staggered and circumferentially aligned
relative to one another.
10. The system of claim 1, further comprising a selective catalytic
reduction (SCR) system configured to receive the mixture of exhaust
reductant and engine exhaust flow directed from the downstream end
of the mixing conduit.
11. A work vehicle, comprising: an engine expelling an engine
exhaust flow; an exhaust conduit configured to receive the engine
exhaust flow the engine; a reductant injector configured to inject
an exhaust reductant into the engine exhaust flow; a mixing conduit
extending lengthwise between an upstream end and a downstream end,
the mixing conduit including an inner conduit wall defining a flow
area through which the engine exhaust flow and the exhaust
reductant are directed between the upstream and downstream ends of
the mixing conduit to allow the exhaust reductant to be at least
partially mixed into the engine exhaust flow, a portion of the
exhaust reductant flowing along the inner conduit wall of the
mixing conduit as a liquid reductant flow; and a plurality of flow
separation elements provided in operative association with the
inner conduit wall of the mixing conduit, the plurality of flow
separation elements configured to separate the liquid reductant
flow from the inner conduit wall as the liquid reductant flow is
directed across the plurality of flow separation elements.
12. The work vehicle of claim 12, wherein the liquid reductant flow
is initiated along the inner conduit wall at a location at or
downstream of a reductant attachment location disposed between the
upstream and downstream ends of the mixing conduit, the plurality
flow separation elements being positioned within the mixing conduit
downstream of the reductant attachment location.
13. The work vehicle of claim 12, further comprising a mixer
positioned within the mixing conduit between the upstream end of
the mixing conduit and the plurality of flow separation
elements.
14. The work vehicle of claim 12, wherein the plurality of flow
separation elements comprise a plurality of radially inwardly
extending protrusions.
15. The work vehicle of claim 12, wherein the plurality of flow
separation elements comprise a plurality of radially outwardly
extending indentions formed in the inner conduit wall.
16. The work vehicle of claim 12, wherein the plurality of flow
separation elements are disposed in an annular array around the
inner conduit wall of the mixing conduit.
17. The work vehicle of claim 12, wherein the plurality of flow
separation elements are circumferentially offset from one
another.
18. The work vehicle of claim 12, wherein the plurality of flow
separation elements are axially staggered relative to one another
along a length of the mixing conduit.
19. The work vehicle of claim 12, wherein the plurality of flow
separation elements are axially staggered and circumferentially
aligned relative to one another.
20. The work vehicle of claim 12, further comprising a selective
catalytic reduction (SCR) system configured to receive the mixture
of exhaust reductant and engine exhaust flow directed from the
downstream end of the mixing conduit.
Description
FIELD OF THE INVENTION
[0001] The present subject matter relates generally to the
treatment of engine exhaust gases, and more particularly, to
systems for separating liquid exhaust reductant from an inner wall
of a mixing conduit.
BACKGROUND OF THE INVENTION
[0002] Typically, work vehicles, such as tractors and other
agricultural vehicles, include an exhaust treatment system for
controlling engine emissions. As is generally understood, exhaust
treatment systems for work vehicles often include a diesel
oxidation catalyst (DOC) system in fluid communication with a
selective catalytic reduction (SCR) system. The DOC system is
generally configured to oxidize carbon monoxide and unburnt
hydrocarbons contained within the engine exhaust and may include a
mixing chamber for mixing an exhaust reductant, such as a diesel
exhaust fluid (DEF) or any other suitable urea-based fluid, into
the engine exhaust. For instance, the exhaust reductant is often
pumped from a reductant tank mounted on and/or within the vehicle
and injected onto the mixing chamber to mix the reductant with the
engine exhaust. The resulting mixture may then be supplied to the
SCR system to allow the reductant to be reacted with a catalyst in
order to reduce the amount of nitrous oxide (NOx) emissions
contained within the engine exhaust.
[0003] One of the challenges inherent with known exhaust treatment
systems lies in obtaining an efficient mixture of exhaust reductant
with the diesel exhaust stream. Under known approaches, the liquid
exhaust reductant is sprayed into the exhaust stream for mixing
therewith. However, after a short distance, a portion of the liquid
exhaust reductant typically centrifuges and impinges onto the walls
of the mixing pipe. The impinged liquid will then gather into a
liquid stream flowing along the wall of the pipe. Once the liquid
stream is formed, a significant portion of the exhaust reductant is
not available for mixture with the exhaust stream prior to entry
into the SCR catalyst. This leads to inefficiencies in the exhaust
treatment system as it is desirable for the exhaust reductant to be
uniformly mixed with the exhaust gas to achieve the desired ratio
of pollutants to reactants. A system with poorly distributed
exhaust reductant is substantially inefficient, requiring excessive
exhaust reductant consumption in order to meet emissions
targets.
[0004] Accordingly, a system for separating liquid exhaust
reductant from a mixing pipe wall so as to make the exhaust
reductant available for mixing with the engine exhaust stream
flowing through the mixing pipe would be welcomed in the
technology.
BRIEF DESCRIPTION OF THE INVENTION
[0005] Aspects and advantages of the invention will be set forth in
part in the following description, or may be obvious from the
description, or may be learned through practice of the
invention.
[0006] In accordance with one embodiment of the present disclosure,
an exhaust treatment system for a work vehicle is provided. The
system includes an exhaust conduit configured to receive an engine
exhaust flow and a reductant injector configured to inject an
exhaust reductant into the engine exhaust flow. The system also
includes a mixing conduit extending lengthwise between an upstream
end and a downstream end. The mixing conduit includes an inner
conduit wall defining a flow area through which the engine exhaust
flow and the exhaust reductant are directed between the upstream
and downstream ends of the mixing conduit to allow the exhaust
reductant to be at least partially mixed into the engine exhaust
flow. A portion of the exhaust reductant flows along the inner
conduit wall of the mixing conduit as a liquid reductant flow. A
plurality of flow separation elements are provided within the
mixing conduit at a location between its upstream and downstream
ends. The flow separation elements are configured to separate the
liquid reductant flow from the inner conduit wall as the liquid
reductant flow is directed across the flow separation elements.
[0007] In accordance with another embodiment of the present
disclosure, a work vehicle is provided. The work vehicle including
an engine expelling an engine exhaust flow, an exhaust conduit
configured to receive the engine exhaust flow the engine, a
reductant injector configured to inject an exhaust reductant into
the engine exhaust flow, and a mixing conduit extending lengthwise
between an upstream end and a downstream end. The mixing conduit
includes an inner conduit wall defining a flow area through which
the engine exhaust flow and the exhaust reductant are directed
between the upstream and downstream ends of the mixing conduit to
allow the exhaust reductant to at least partially be mixed into the
engine exhaust flow. A portion of the exhaust reductant flows along
the inner conduit wall of the mixing conduit as a liquid reductant
flow. The work vehicle also includes a plurality of flow separation
elements within the mixing conduit at a location between its
upstream and downstream ends. The flow separation elements are
configured to separate the liquid reductant flow from the inner
conduit wall as the liquid reductant flow is directed across the
flow separation elements.
[0008] In accordance with one embodiment of the present disclosure,
an exhaust treatment system for a work vehicle is provided. The
system includes an exhaust conduit configured to receive an engine
exhaust flow and a reductant injector configured to inject an
exhaust reductant into the engine exhaust flow. The system also
includes a mixing conduit extending lengthwise between an upstream
end and a downstream end. The mixing conduit includes an inner
conduit wall defining a flow area through which the engine exhaust
flow and the exhaust reductant are directed between the upstream
and downstream ends of the mixing conduit to allow the exhaust
reductant to be at least partially mixed into the engine exhaust
flow. A portion of the exhaust reductant flows along the inner
conduit wall of the mixing conduit as a liquid reductant flow. A
flow separation nozzle is provided within the mixing conduit at a
location between its upstream and downstream ends. The flow
separation nozzle includes a nozzle wall extending between an
upstream wall end and a downstream wall end. The nozzle wall
defines a radially inwardly converging profile between its upstream
and downstream wall ends. The flow separation nozzle is positioned
within the mixing conduit such that the liquid reductant flow
flowing along the inner conduit wall is directed across the nozzle
wall and separates from the flow separation nozzle for mixing with
the engine exhaust flow flowing through the flow separation
nozzle.
[0009] In accordance with another embodiment of the present
disclosure, a work vehicle is provided. The work vehicle including
an engine expelling an engine exhaust flow, an exhaust conduit
configured to receive the engine exhaust flow the engine, a
reductant injector configured to inject an exhaust reductant into
the engine exhaust flow, and a mixing conduit extending lengthwise
between an upstream end and a downstream end. The mixing conduit
includes an inner conduit wall defining a flow area through which
the engine exhaust flow and the exhaust reductant are directed
between the upstream and downstream ends of the mixing conduit to
allow the exhaust reductant to be at least partially mixed into the
engine exhaust flow. A portion of the exhaust reductant flows along
the inner conduit wall of the mixing conduit as a liquid reductant
flow. The work vehicle also includes a flow separation nozzle
provided within the mixing conduit at a location between its
upstream and downstream ends. The flow separation nozzle includes a
nozzle wall extending between an upstream wall end and a downstream
wall end. The nozzle wall defines a radially inwardly converging
profile between its upstream and downstream wall ends. The flow
separation nozzle is positioned within the mixing conduit such that
the liquid reductant flow flowing along the inner conduit wall is
directed across the nozzle wall and separates from the flow
separation nozzle for mixing with the engine exhaust flow flowing
through the flow separation nozzle.
[0010] These and other features, aspects and advantages of the
present invention will become better understood with reference to
the following description and appended claims. The accompanying
drawings, which are incorporated in and constitute a part of this
specification, illustrate embodiments of the invention and,
together with the description, serve to explain the principles of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A full and enabling disclosure of the present invention,
including the best mode thereof, directed to one of ordinary skill
in the art, is set forth in the specification, which makes
reference to the appended figures, in which:
[0012] FIG. 1 illustrates a side view of one embodiment of a work
vehicle in accordance with aspects of the present subject
matter;
[0013] FIG. 2 illustrates a schematic view of one embodiment of an
exhaust treatment system suitable for use with a work vehicle,
particularly illustrating a flow separation region associated with
a mixing pipe or conduit of the system in accordance with aspects
of the present subject matter;
[0014] FIG. 3 illustrates a cross-sectional view of a portion of
the exhaust treatment system shown in FIG. 2 taken about line
3,6-3,6, particularly illustrating an embodiment of the exhaust
treatment system in which the flow separation region includes or is
configured as a flow separation nozzle;
[0015] FIG. 4 illustrates a cross-sectional view of another
embodiment of the flow separation nozzle shown in FIG. 3 in
accordance with aspects of the present subject matter;
[0016] FIG. 5 illustrates a cross-sectional view of a further
embodiment of the flow separation nozzle shown in FIG. 3 in
accordance with aspects of the present subject matter;
[0017] FIG. 6 illustrates another cross-sectional view of a portion
of the exhaust treatment system shown in FIG. 2 taken about line
3,6-3,6, particularly illustrating an embodiment of the exhaust
treatment system in which the flow separation region includes or is
configured as a plurality of flow separation elements in accordance
with aspects of the present subject matter;
[0018] FIG. 7 illustrates a cross-sectional view of the portion of
the exhaust treatment system shown in FIG. 6 taken about line 7-7
in accordance with aspects of the present subject matter;
[0019] FIGS. 8A-8G illustrate differing views of various
embodiments of suitably shaped elements that can be used as flow
separation elements in accordance with aspects of the present
subject matter.
[0020] FIG. 9 illustrates another similar cross-sectional view of
the portion of the exhaust treatment system shown in FIGS. 6 and 7,
particularly illustrating an embodiment including separate rows of
circumferentially offset, axially aligned flow separation elements
in accordance with aspects of the present subject matter;
[0021] FIG. 10 illustrates a similar cross-sectional view of the
portion of the exhaust treatment system shown in FIGS. 6 and 7,
particularly illustrating an embodiment including separate rows of
circumferentially aligned, axially offset flow separation elements
in accordance with aspects of the present subject matter;
[0022] FIG. 11 illustrates a similar cross-sectional view of the
portion of the exhaust treatment system shown in FIG. 6,
particularly illustrating another embodiment of a suitable
configuration for the flow separation elements in accordance with
aspects of the present subject matter; and
[0023] FIG. 12 illustrates a cross-sectional view of the portion of
the exhaust treatment system shown in FIG. 11 taken about line
12-12 in accordance with aspects of the present subject matter.
[0024] Repeat use of reference characters in the present
specification and drawings is intended to represent the same or
analogous features or elements of the present technology.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Reference now will be made in detail to embodiments of the
invention, one or more examples of which are illustrated in the
drawings. Each example is provided by way of explanation of the
invention, not limitation of the invention. In fact, it will be
apparent to those skilled in the art that various modifications and
variations can be made in the present invention without departing
from the scope or spirit of the invention. For instance, features
illustrated or described as part of one embodiment can be used with
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention covers such modifications and
variations as come within the scope of the appended claims and
their equivalents.
[0026] In general, the present subject matter is directed to a
system for treating the engine exhaust of a work vehicle.
Specifically, in several embodiments, the present subject matter is
directed to systems for separating a stream of liquid exhaust
reductant from the sidewall or inner conduit wall of a mixing pipe
or conduit of an exhaust treatment system. Exhaust reductant is an
important, consumable solution employed in treating diesel exhaust
to limit air pollution, specifically nitrous oxides. To reduce the
level of nitrous oxides in the diesel exhaust stream during engine
operations, an exhaust reductant (e.g., a urea-water solution) is
sprayed from a storage tank into the exhaust stream at a point
upstream of a selective catalytic reduction (SCR) system.
Optimally, all of the exhaust reductant mixes with the exhaust
stream and, in the presence of the catalytic components, reacts
with the nitrous oxides to produce harmless nitrogen and water. If
more exhaust reductant is introduced than is required to react with
the amount of nitrous oxide present, then the excess exhaust
reductant is not only wasted, requiring more frequent replenishment
of the storage tank, but the excess also tends to crystalize and
accumulate ("caking"), thereby further reducing system efficiency.
On the other hand, if an insufficient amount of exhaust reductant
is available to react with the amount of nitrous oxide in the
exhaust stream, the pollutant may not be reduced below
air-pollution limits.
[0027] As indicated above, upon spraying or introducing the exhaust
reductant into the flow of engine exhaust, a portion of the exhaust
reductant often accumulates into a liquid stream along an interior
wall of the mixing conduit and flows in a generally helical path
along the length of the conduit to the downstream selective
catalytic reduction (SCR) system. As a result, this liquid stream
is unavailable for mixing with the stream of exhaust gases flowing
through the mixing conduit and is also not susceptible to
evaporation based on heat transfer from the interior wall of the
conduit. It is thus desirable to separate this flow of liquid
exhaust reductant from the interior wall of the mixing conduit and
reintroduce the reductant back into the exhaust stream.
[0028] In several embodiments of the present disclosure, to allow
for separation of the stream of exhaust reductant from the interior
wall of the mixing conduit, a flow separation nozzle may be
incorporated into and/or otherwise provided in operative
association with the mixing conduit downstream of the injection
point for the exhaust reductant. In general, the flow separation
nozzle may define a generally radially inwardly converging profile
or configuration such that an upstream diameter of the nozzle is
greater than its downstream diameter. Thus, as the liquid stream of
exhaust reductant encounters the leading edge of the flow
separation nozzle, the liquid reductant stream is separated from
the inner wall of the mixing conduit and travels across the length
of the nozzle face along its radially inwardly converging profile
toward the centerline of the mixing conduit. As the liquid
reductant stream reaches a downstream end or edge of the nozzle,
the liquid stream separates from the nozzle face and is
reintroduced into the stream of exhaust gases flowing through the
nozzle. Specifically, at the downstream end of the nozzle, the
liquid reductant stream may be picked up and carried by the flow of
engine exhaust being accelerated through the converging nozzle,
thereby facilitating enhanced mixing of the reductant within the
exhaust.
[0029] Moreover, in addition to the flow separation nozzle (or as
an alternative thereto), a plurality of individual flow separation
elements may be incorporated within or otherwise provided in
operative association with the mixing conduit of the exhaust
treatment system downstream of the injection point of the exhaust
reductant to allow the liquid reductant stream to be separated from
the interior wall of the mixing conduit. In several embodiments,
the flow separation elements may be configured as a plurality of
turbulators, such as a plurality of protrusions, ribs, or other
elements extending radially inwardly from the inner wall of the
mixing conduit or a plurality of indentations or recesses formed in
the inner wall of the mixing conduit. In such embodiments, when the
liquid reductant stream encounters the flow separation elements,
the portion of the liquid stream contacting or otherwise
interacting with the flow separation element may be deflected from
the inner wall of the mixing conduit and into the stream of exhaust
gases for mixing therewith.
[0030] Referring now to the drawings, FIG. 1 illustrates a side
view of one embodiment of a work vehicle 100. As shown, the work
vehicle 100 is configured as an agricultural tractor. However, in
other embodiments, the work vehicle 100 may be configured as any
other suitable work vehicle known in the art, such as various other
agricultural vehicles, earth-moving vehicles, road vehicles,
all-terrain vehicles, off-road vehicles, loaders and/or the
like.
[0031] As shown in FIG. 1, the work vehicle 100 includes a pair of
front wheels 102, a pair or rear wheels 104, and a chassis 106
coupled to and supported by the wheels 102, 104. An operator's cab
108 may be supported by a portion of the chassis 106 and may house
various control devices 110, 112 (e.g., levers, pedals, control
panels and/or the like) for permitting an operator to control the
operation of the work vehicle 100. Additionally, the work vehicle
100 may include an engine 118 and a transmission 114 mounted on the
chassis 106. The transmission 114 may be operably coupled to the
engine 118 and may provide variably adjusted gear ratios for
transferring engine power to the wheels 104 via a differential
116.
[0032] Moreover, the work vehicle 100 may also include an exhaust
treatment system 200 for reducing the amount emissions contained
within the exhaust from the engine 118. For instance, engine
exhaust expelled from the engine 118 may be directed through the
exhaust treatment system 200 to allow the levels of nitrous oxide
(NOx) emissions contained within the exhaust to be reduced
significantly. The cleaned exhaust gases may then be expelled from
the exhaust treatment system 200 into the surrounding environment
via an exhaust pipe 120 of the work vehicle 100.
[0033] It should be appreciated that the configuration of the work
vehicle 100 described above and shown in FIG. 1 is provided only to
place the present subject matter in an exemplary field of use.
Thus, it should be appreciated that the present subject matter may
be readily adaptable to any manner of work vehicle configuration
100. For example, in an alternative embodiment, a separate frame or
chassis may be provided to which the engine 118, transmission 114,
and differential 116 are coupled, a configuration common in smaller
tractors. Still other configurations may use an articulated chassis
to steer the work vehicle 100, or rely on tracks in lieu of the
wheels 102, 104. Additionally, although not shown, the work vehicle
100 may also be configured to be operably coupled to any suitable
type of work implement, such as a trailer, spray boom, manure tank,
feed grinder, plow and/or the like.
[0034] Referring now to FIG. 2, a schematic diagram of one
embodiment of an exhaust treatment system 200 suitable for use with
a work vehicle 100 is illustrated in accordance with aspects of the
present subject matter. As represented in FIG. 2, the exhaust
treatment system includes an exhaust conduit 202, a diesel
oxidation catalyst (DOC) system 204, a mixing conduit 208, and a
selective catalytic reduction (SCR) system 214. During operation of
the work vehicle 10, exhaust expelled from the engine 118 is
received by the exhaust conduit 202 and flows through the conduit
202 to the DOC system 204. As is generally understood, the DOC
system 204 is configured to reduce the levels of carbon monoxide
and hydrocarbons present in the engine exhaust. For example, as
shown in FIG. 2, the DOC system 204 includes a canister or chamber
205 for receiving engine exhaust from the exhaust conduit 202, with
the chamber 205 being in flow communication with an upstream end
206 of the mixing conduit 208. In addition, the DOC system 204
includes a reductant injector nozzle 222 provided in association
with the chamber 205 at a location at or adjacent to the upstream
end 206 of the mixing conduit 208 to allow an exhaust reductant
218, such as a diesel exhaust fluid (DEF) or any other suitable
urea-based fluid, to be injected into the stream of exhaust gases
flowing through the chamber 205. For instance, as shown in FIG. 2,
the reductant injector nozzle 222 may be fluidly coupled to a
source of exhaust reductant (e.g., storage tank 216) via a hose or
other fluid coupling 220 to allow liquid exhaust reductant to be
supplied to the nozzle 222. The engine exhaust and exhaust
reductant flowing into the upstream end 206 of the mixing conduit
208 are then directed through the conduit 208 to the downstream end
210 thereof for receipt by the SCR system 214, within which the
mixture of exhaust/reductant is reacted with a catalyst to reduce
the amount of nitrous oxide (NOx) emissions contained within the
engine exhaust. The treated exhaust is then expelled from the
exhaust treatment system via the exhaust pipe 120 into the
atmosphere.
[0035] As the exhaust/reductant flows into and through the mixing
conduit 218, a portion of the reductant evaporates and mixes with
the engine exhaust. However, as indicated above, some portion of
the injected exhaust reductant 218 typically does not initially
evaporate/mix with the engine exhaust, but, instead impinges on an
inner conduit wall 212 of the mixing conduit 208 and forms a flow
of liquid reductant along the wall 212. The attachment of the
liquid exhaust reductant to the conduit wall 212 generally occurs
at a location downstream of the upstream end 206 of the mixing
conduit 208, which, for purposes of description, will generally be
referred to herein as the "reductant attachment location" and is
labeled as "S" in the figures. It should be appreciated that the
specific downstream location of the reductant attachment location S
may generally vary depending on the configuration of the mixing
conduit 208 and/or the reductant injector nozzle 222, the flow
properties of the engine exhaust and/or the reductant within the
DOC system 204 and/or the mixing conduit 208, and/or other relevant
factors. However, in one embodiment, the reductant attachment
location S may generally be defined at a downstream location
separated from the upstream end 206 of the mixing conduit 208 by a
distance T that is equal to greater than 1% of the total length of
the mixing conduit 208 defined between its upstream and downstream
ends 206, 210, such as a distance T greater than 2% of the total
length of the mixing conduit 208 or greater than 5% of the total
length of the mixing conduit 208 or greater than 10% of the total
length of the mixing conduit 208.
[0036] To allow for separation of the liquid reductant flow from
the inner conduit wall 212, at least one flow separation region 300
is provided within or in operative association with the mixing
conduit 208 at a location downstream of the reductant attachment
location S and upstream of the downstream end 210 of the mixing
conduit 210. As will be described below, one or more flow
separation features (e.g., one or more nozzles and/or flow
separation elements) may form part of or may be included within the
flow separation region 300 of the mixing conduit 208 that are
configured to separate the liquid reductant flow from the inner
conduit wall 212. As a result, upon encountering the flow
separation region 300, at least a portion of the liquid reductant
flow is separated from the inner conduit wall 212 and directed
generally toward the centerline of the mixing conduit 208. In so
doing, at least a portion of the liquid reductant flow is
reintroduced to, and mixed with, the engine exhaust flow
[0037] Still referring to FIG. 2, it should be appreciated that, in
some applications following reintroduction of the liquid reductant
flow into the exhaust flow at the flow separation region 300,
portions of the exhaust reductant 218 may still have a tendency to
centrifuge and impinge on the inner conduit wall 212 at a location
downstream of the flow separation region 300. In such embodiments,
one or more secondary flow separation regions 302 may be provided
downstream of the initial flow separation region 300 to allow for
the liquid reductant flow to again be separated from the inner
conduit wall 212 at such downstream locations. Each secondary flow
separation region 302 may similarly include one or more flow
separation features (e.g., one or more nozzles and/or flow
separation elements) configured to separate the liquid reductant
flow from the inner conduit wall 212.
[0038] It should also be appreciated that, in some embodiments, the
exhaust treatment system 200 may further include a mixing component
or mixer 228 installed within the mixing conduit 208 to impart
rotation or turbulence into the engine exhaust flow. As shown in
FIG. 2, in one embodiment, the mixer 228 may be installed within
the mixing conduit 208 at a location between the upstream end 206
of the conduit 208 and the initial flow separation region 300, such
as at a location between the upstream end 206 of the conduit 208
and the reductant attachment location S.
[0039] Referring now to FIG. 3, a cross-sectional view of a portion
of the mixing conduit 208 of the exhaust treatment system 200 shown
in FIG. 2 taken about line 3,6-3,6 is illustrated in accordance
with aspects of the present subject matter, particularly
illustrating one embodiment of the flow separation region 300 of
the mixing conduit 208. As shown in FIG. 3, the flow separation
region 300 of the mixing conduit 208 includes a flow separation
nozzle 304 located downstream of the reductant attachment location
S. In the illustrated embodiment, the flow separation nozzle 304
corresponds to a separate insert configured to be installed within
the mixing conduit 208. However, in other embodiments, the flow
separation nozzle 304 may be formed integrally with the mixing
conduit 208 and/or may be included as part of a separate conduit
section forming an axial section of the mixing conduit 208.
[0040] As shown in FIG. 3, the flow separation nozzle 304 includes
a nozzle wall 306 extending between an upstream wall end 308 and a
downstream wall end 310 of the nozzle 304. As shown in the
illustrated embodiment, the nozzle wall 306 defines a radially
converging nozzle profile between the upstream and downstream wall
ends 308, 310 such that an upstream diameter D.sub.1 of the nozzle
defined at the upstream wall end 308 is greater than a downstream
diameter D.sub.2 of the nozzle at the downstream wall end 310. For
example, in one embodiment, the upstream diameter D.sub.1 may
generally be equal to the inner diameter of the mixing conduit
while the downstream diameter D.sub.2 is equal to a diameter
ranging from about 50% to about 95% of the inner diameter of the
mixing conduit. In such an embodiment, the nozzle wall 306 may
generally define a cross-sectional profile having a radially
inclined plane where the upstream wall end 308 is in contact with
the inner conduit wall 212 of the mixing conduit 208 and the
downstream wall end 310 is positioned axially downstream of and
radially inwardly relative to the upstream wall end 308. It should
be appreciated that the converging profile of the nozzle wall 306
dictates that the diameter of the flow area within the mixing
conduit 208 decreases along a length of the nozzle wall 306.
[0041] Given the radially inwardly converging configuration of the
flow separation nozzle 304 shown in FIG. 3, the nozzle 304 may be
configured to separate the liquid reductant flow (represented by
lines 226 in FIG. 3) from the inner conduit wall 212 and
reintroduce such flow 226 back into the engine exhaust flow
(represented in FIG. 3 by lines 224) directed through the nozzle
304. Specifically, when the liquid reductant flow 226 flowing along
the inner conduit wall 212 encounters the upstream wall end 308 of
the nozzle 304, the liquid reductant flow 226 is directed along the
radially inwardly converging nozzle wall 306 towards the downstream
wall end 310 of the nozzle 304. Upon reaching the downstream wall
end 310, the liquid reductant flow 226 separates from the nozzle
wall 306 and is reintroduced to the engine exhaust flow 224, where
the exhaust reductant 218 is again available for mixing with the
engine exhaust flow 224. In doing so, the increased velocity of the
engine exhaust gases flowing through the converging nozzle 304 may
assist in forcing the liquid reductant flow 226 away from the inner
conduit wall 212 as it flows across the nozzle wall 306 and
separates therefrom at the downstream wall end 310 of the nozzle
304 It should be appreciated that, although the nozzle has been
described above in terms of a converging nozzle with a
right-triangular profile, the nozzle could also define a
converging-diverging profile with any triangular profile or define
any other suitable nozzle profile.
[0042] Referring now to FIG. 4, a cross-sectional view of another
embodiment of a suitable nozzle configuration for the flow
separation nozzle 304 described above with reference to FIG. 3 is
illustrated in accordance with aspects of the present subject
matter. As shown in FIG. 4, unlike the straight or planar
converging cross-sectional profile described above, the nozzle wall
306 defines an arcuate or curved cross-sectional profile between
the upstream wall end 308 and the downstream wall end 310 of the
nozzle 304. For instance, in the illustrated embodiment, the nozzle
wall 306 defines a concavely shaped cross-sectional profile between
the upstream and downstream wall ends 308, 310 of the nozzle 304.
However, in other embodiments, the nozzle wall 306 may define any
other suitable cross-sectional profile between the ends 308, 310 of
the nozzle 304, such as a wavy profile, a stepped profile, and/or
the like.
[0043] Referring now to FIG. 5, another cross-sectional view of a
further embodiment of a suitable nozzle configuration for the flow
separation nozzle 304 described above with reference to FIG. 3 is
illustrated in accordance with aspects of the present subject
matter. As shown in FIG. 5, the flow separation nozzle 304 is
generally configured the same as or similar to the nozzle 304
described above with reference to FIG. 3, such as by including a
nozzle wall defining a converging, planar cross-sectional profile
between the downstream and upstream walls ends 308, 310 of the
nozzle 304. However, unlike the embodiment described above, the
nozzle wall 306 includes a plurality of flow separation elements
312 coupled thereto or formed thereon. As will be described below,
such flow separation elements 312 may correspond to any suitable
elements that are configured to facilitate separation of the liquid
reductant flow from an adjacent surface or wall. In several
embodiments, each flow separation element may correspond to a
separate turbulator-like element configured to disrupt or otherwise
alter the flow of liquid reductant along the nozzle wall 306. For
instance, as shown in FIG. 5, each flow separation element 312
corresponds to a ridge, rib, or other protrusion extending radially
inwardly from the nozzle wall 306. However, in other embodiments,
the flow separation elements 312 may correspond to dimples,
recesses, or any other radially inwardly extending indentations
defined in or relative to the nozzle wall 306 or a combination of
radially outwardly projecting protrusions and radially inwardly
extending indentations.
[0044] It should be appreciated that, although the above-described
nozzle configurations are generally described with reference to the
initial flow separation region 300 of FIG. 2, the same or similar
nozzle configurations may also be provided in association any other
flow separation region associated with the mixing conduit, such as
any of the secondary or downstream flow separation regions 302. For
instance, in one embodiment, each secondary or downstream flow
separation region 302 may include a flow separation nozzle in
association therewith.
[0045] Referring now to FIGS. 6 and 7, further cross-sectional
views of a portion of the mixing conduit 208 of the exhaust
treatment system 200 shown in FIG. 2 are illustrated in accordance
with aspects of the present subject matter, particularly
illustrating another embodiment of the flow separation region 300
of the mixing conduit 208. Specifically, FIG. 6 illustrates a
cross-sectional view of the mixing conduit 208 shown in FIG, 2
taken about line 3,6-3,6. Additionally, FIG. 7 illustrates a
cross-sectional view of the mixing conduit shown in FIG. 6 taken
about line 7-7.
[0046] As shown in FIGS. 6 and 7, the flow separation region 300 of
the mixing conduit 208 includes a plurality of flow separation
elements 314 provided in association with the inner conduit wall
212 at a location downstream of the reductant attachment location
S. Specifically, as shown in the illustrated embodiment, each flow
separation element 314 corresponds to a rib, or other protrusion
extending radially inwardly from the inner conduit wall 212 into
the flow area defined by the mixing conduit 208. As a result, the
flow separation elements 314 may be configured to disrupt or
otherwise alter the flow of liquid reductant along the inner
conduit wall 212. For instance, as the liquid reductant flow 226
advances along the inner conduit wall 212 from the reductant
attachment location S, one or more portions of the liquid reductant
flow 226 encounter or contact the flow separation elements 314,
thereby facilitating separation of such portion(s) of the liquid
reductant flow from the inner conduit wall 212 to allow the
reductant 218 to be intermixed with the engine exhaust flow
224.
[0047] It should be appreciated that, when the flow separation
elements 314 are configured as radially inwardly extending
protrusions, such elements 314 may generally have any suitable
shape(s) that facilitates separation of at least a portion of the
liquid reductant flow 226 from the inner conduit wall 212 when such
portion of the flow 226 contacts or encounters a given flow
separation element 312. For example, FIGS. 8A-8G illustrate various
examples of suitable shapes or profiles that may be utilized for
the flow separation elements 314. Specifically, one or more of the
flow separation elements 314 may be configured as a pyramid (FIG.
8A), a cone (FIG. 8B), a frustum (FIG. 8C), a hemisphere (FIG. 8D),
a cylinder (FIG. 8E), and/or any other suitable shape. In another
embodiment, one or more of the flow separation elements 314 may
have a hybrid shape, e.g., a generally triangular profile having a
concave face, as depicted in FIG. 8F. In still other embodiments,
the flow separation elements 314 may include shapes and forms such
as ribs, ridges, turbulator tape, moniliforms, wires,
hemi-lachrymiforms, hemi-reniforms, arches, cruciforms,
aciculiforms or prisms.
[0048] Referring back to FIGS. 6 and 7, as shown in the illustrated
embodiment, the flow separation elements 314 are generally disposed
in an annular array around the inner conduit wall 212 of the mixing
conduit 208. Specifically, as shown in FIGS. 6 and 7, the flow
separation elements 314 are all positioned at the same axial
location along the length of the mixing conduit 208, with each flow
separation element 314 being spaced apart circumferentially from
adjacent or neighboring flow separation elements 314 around the
inner perimeter of the conduit 208. However, in other embodiments,
the flow separation elements 314 may be provided in any other
suitable arrangement within the mixing conduit 208, such as by
being axially staggered or offset and/or by being circumferentially
aligned. For instance, FIG. 9 illustrates an arrangement in which
the flow separation elements 314 are provided in separate annular
arrays. Specifically, as shown in FIG. 9, a first annular array 316
of flow separation elements is provided at a first axial location
downstream of the reductant attachment location S and a second
annular array 318 of flow separation elements is provided
downstream of the first annular array 316 at a second axial
location. As shown in FIG. 9, the annular arrays 316, 318 of flow
separation elements are axially staggered relative to one another
along a length of the mixing conduit. Additionally, as shown in
FIG. 9, the flow separation elements 314 of the first array 316 are
circumferentially offset from the flow separation elements 314 of
the second array 318. However, in other embodiments, corresponding
flow separation elements 314 of the first and second arrays 316,
318 may be configured to be circumferentially aligned with each
other. Moreover, yet another example of a suitable arrangement for
the flow separation elements 314 is illustrated in FIG. 10. Similar
to the embodiment described above, the flow separation elements 314
are provided in two separate arrays (e.g., a first array 316 and a
second array 318). However, unlike the embodiment described above
with reference to FIG. 9, the first and second arrays 316, 318
include circumferentially aligned flow separation elements, with
each array including axially staggered flow separation elements
314.
[0049] Referring now to FIGS. 11 and 12, similar cross-sectional
views of the portion of the mixing conduit 208 of the exhaust
treatment system 200 shown in FIGS. 6 and 7 are illustrated in
accordance with aspects of the present subject matter.
Specifically, FIG. 11 illustrates a similar cross-sectional view of
the mixing conduit 208 as that shown in FIG. 6, particularly
illustrating yet another embodiment of the flow separation region
300 of the mixing conduit 208. Additionally, FIG. 12 illustrates a
cross-sectional view of the mixing conduit shown in FIG. 11 taken
about line 12-12.
[0050] As shown in FIGS. 11 and 12, similar to that shown in FIGS.
6 and 7, the flow separation region 300 of the mixing conduit 208
includes a plurality of flow separation elements 314 provided in
association with the inner conduit wall 212 at a location
downstream of the reductant attachment location S. However, unlike
the embodiments described above in which the flow separation
elements correspond to radially inwardly projecting protrusions,
the flow separation elements 314 correspond to radially inwardly
extending indentations defined relative to the inner conduit wall
212 of the mixing conduit. As a result, the flow separation
elements 314 may be configured to disrupt or otherwise alter the
flow of liquid reductant along the inner conduit wall 212. For
instance, as the liquid reductant flow 226 advances along the inner
conduit wall 212 from the reductant attachment location S, one or
more portions of the liquid reductant flow 226 encounters the flow
separation elements 314, thereby facilitating separation of such
portion(s) of the liquid reductant flow from the inner conduit wall
212 to allow the reductant 218 to be intermixed with the engine
exhaust flow 224.
[0051] It should be appreciated that, when the flow separation
elements 314 are configured as indentations, each element 314 may
generally have any suitable shape(s) that facilitates separation of
at least a portion of the liquid reductant flow 226 from the inner
conduit wall 212. when such portion of the flow 226 encounters a
given flow separation element 314. For example, as depicted in
FIGS. 11 and 12, the indentations may he dimples, or as depicted in
FIG. 8G, the indentations may be an area of knurling. Additionally,
the indentations may take the negative form of any of the various
protrusion shapes described above with reference to FIGS.
8A-8F.
[0052] It should be appreciated that, although the above-described
configurations for the flow separation elements 314 are generally
described with reference to the initial flow separation region 300
of FIG. 2, the same or similar flow separation element
configurations may also be provided in association with any other
flow separation region associated with the mixing conduit, such as
any of the secondary or downstream flow separation regions 302. For
instance, in one embodiment, each secondary or downstream flow
separation region 302 may include a plurality of flow separation
elements 314 positioned therein.
[0053] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they include structural elements that do not
differ from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *