WO2019143373A1

WO2019143373A1 - Decomposition chamber for aftertreatment systems

Info

Publication number: WO2019143373A1
Application number: PCT/US2018/027580
Authority: WO
Inventors: Ryan M. Johnson; Udit Bhaveshkumar Shah; Pradnya Chandrakant JOSHI; Samuel Johnson; Mahendra Mittapalli; Enoch NANDURU; Kartiki Jagtap; Suraj D. KHALATE; Vinay Kumar Joshi
Original assignee: Cummins Emission Solutions Inc.
Priority date: 2018-01-16
Filing date: 2018-04-13
Publication date: 2019-07-25
Also published as: CN110337324A; CN110337324B

Abstract

A decomposition chamber for an after treatment system includes a first wall; a second wall; and a third wall. A first plenum is defined between the first wall and the second wall, the first plenum positioned along a longitudinal axis of the decomposition chamber, the first plenum defining a first plenum internal volume. A second plenum is defined between the second wall and the third wall, the second plenum position along the longitudinal axis of the decomposition chamber such that the second plenum is positioned around at least a portion of the first plenum.

Description

DECOMPOSITION CHAMBER FOR AFTERTREATMENT SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and benefit of Indian Patent Application

No. 201841001734, filed January 16, 2018 and entitled“Decomposition Chamber for

Aftertreatment Systems,” the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

[0002] The present disclosure relates generally to aftertreatment systems for use with internal combustion (IC) engines.

BACKGROUND

[0003] Exhaust aftertreatment systems are used to receive and treat exhaust gas generated by IC engines. Generally exhaust gas aftertreatment systems comprise any of several different components to reduce the levels of harmful exhaust emissions present in exhaust gas. For example, certain exhaust gas aftertreatment systems for diesel-powered IC engines comprise a selective catalytic reduction (SCR) system, including a catalyst formulated to convert NOx (NO and N0₂ in some fraction) into harmless nitrogen gas (N₂) and water vapor (H₂0) in the presence of ammonia (MR).

[0004] Generally in such aftertreatment systems, an exhaust reductant (e.g., a diesel exhaust fluid such as urea) is injected into the SCR system to provide a source of ammonia and mixed with the exhaust gas to partially reduce the NOx gases. The reduction byproducts of the exhaust gas are then fluidly communicated to the catalyst included in the SCR system to decompose substantially all of the NOx gases into relatively harmless byproducts that are expelled out of the aftertreatment system.

[0005] Aftertreatment systems often include a decomposition chamber or tube upstream of the SCR system. The reductant is inserted in the decomposition chamber which serves to provide a passage to allow decomposing, mixing and distribution of the reductant with the exhaust gas before the exhaust gas flows into the SCR system. Conventional decomposition chambers have substantial axial lengths, which requires more packaging space and may also exert a higher pressure drop on the exhaust gas. Furthermore, conventional decomposition chambers experience heat loss due to inefficient thermal management which leads to formation of reductant deposits.

SUMMARY

[0006] Embodiments described herein relate generally to a decomposition chamber for use with aftertreatment systems, and in particular to a U-shaped decomposition chamber that includes a first chamber structured to receive an exhaust gas first portion, and a second chamber positioned outside the first chamber and structured to receive an exhaust gas second portion.

The exhaust gas second portion flows around at least a portion of the first chamber so as to maintain a temperature of the exhaust gas first portion flowing through the first chamber.

[0007] In one embodiment, a decomposition chamber for an aftertreatment system includes a first wall; a second wall; and a third wall. A first plenum is defined between the first wall and the second wall. The first plenum is positioned along a longitudinal axis of the decomposition chamber, the first plenum defining a first plenum internal volume. A first inlet is defined at a first end of the first plenum between the first wall and the second wall. The first inlet is structured to receive an exhaust gas first portion of an exhaust gas in a first direction

perpendicular to the longitudinal axis. A first outlet is defined on a second end of the first plenum opposite the first end between the first wall and the second wall. The first outlet is structured to allow the exhaust gas first portion to exit in a second direction opposite the first direction perpendicular to the longitudinal axis. A second plenum is defined between the second wall and the third wall. The second plenum is positioned along the longitudinal axis of the decomposition chamber such that the second plenum is positioned around at least a portion of the first plenum. The second plenum defines a second plenum internal volume. A second inlet is defined between the second wall and third wall to the first inlet. The second inlet is structured to receive an exhaust gas second portion of the exhaust gas, the exhaust gas second portion flowing into the second plenum so as to flow around the first plenum and maintain a temperature of the exhaust gas first portion flowing through the first plenum. [0008] In another embodiment, a decomposition chamber for an aftertreatment system comprises a first wall, a second wall, and a third wall. A first plenum is defined between the first wall and the second wall. The first plenum defines a first plenum internal volume, a first inlet defined at a first end of the first plenum between the first wall and the second wall, and a first outlet defined on a second end of the first plenum opposite the first end between the first wall and the second wall. A second plenum is defined between the second wall and the third wall. The second plenum is positioned around at least a portion of the first plenum. The second plenum defining a second plenum internal volume, and a second inlet defined between the second wall and third wall to the first inlet, the second inlet structured to receive an exhaust gas second portion of the exhaust gas, the exhaust gas second portion flowing into the second plenum so as to flow around the first plenum and maintain a temperature of the exhaust gas first portion flowing through the first plenum.

[0009] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the subject matter disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several

implementations in accordance with the disclosure and are therefore not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

[0011] FIG. l is a perspective view of a decomposition chamber, according to an embodiment.

[0012] FIG. 2 is a rear cross-section view of the decomposition chamber of FIG. 1. [0013] FIG. 3 is a front cross-section view of the decomposition chamber of FIG. 1.

[0014] FIG. 4 is a top cross-section view of the decomposition chamber of FIG. 1.

[0015] FIG. 5 is a side cross-section view of the decomposition chamber of FIG. 1.

[0016] FIG. 6 is another side cross-section view of a portion of the decomposition chamber of FIG. 1

[0017] FIG. 7 is a top perspective view of a portion of the decomposition chamber of FIG. 1 showing a mounting plate positioned thereon.

[0018] FIG. 8 is a top perspective view of a portion of a decomposition chamber, according to another embodiment.

[0019] FIG. 9 is a side cross-section view of the portion of the decomposition chamber of FIG. 8.

[0020] FIG. 10 is a rear view of a decomposition chamber, according to yet another embodiment.

[0021] FIG. 11 is a rear view of a decomposition chamber, according to still another embodiment.

[0022] FIG. 12 is a side view of the decomposition chamber of FIG. 1.

[0023] FIG. 13 is a rear view of the decomposition chamber of FIG. 1.

[0024] FIG. 14 is a front cross-section view of a portion of the decomposition chamber of

FIG. 1.

[0025] FIG. 15 is a top cross-section view of a portion of the decomposition chamber of FIG. 1.

[0026] FIG. 16 is a rear view of a first plenum of a decomposition chamber, according to another embodiment. [0027] FIG. 17 is a front cross-section view of a portion of the decomposition chamber of FIG. 16.

[0028] FIG. 18 is a side cross-section view of a decomposition chamber, according to another embodiment.

[0029] FIG. 19 is an enlarged view of a portion of the decomposition chamber shown in FIG. 18.

[0030] FIG. 20 is a side cross-section view of a portion of a decomposition chamber, according to yet another embodiment.

[0031] FIG. 21 is a rear cross-section view of a portion of the decomposition chamber of FIG. 20.

[0032] FIG. 22 is a side cross-section view of a portion of a decomposition chamber, according to still another embodiment.

[0033] FIG. 23 is a rear cross-section view of a portion of the decomposition chamber of FIG. 22.

[0034] FIG. 24 is a side cross-section view of a portion of a decomposition chamber, according to a particular embodiment.

[0035] FIG. 25 is a side cross-section view of a portion of the decomposition chamber of FIG. 24.

[0036] FIG. 26 is a side cross-section view of a portion of a decomposition chamber, according to yet another embodiment.

[0037] FIG. 27 is a side cross-section of the decomposition chamber of FIG. 26.

[0038] FIG. 28 is a side cross-section view of a portion of a decomposition chamber, according to still another embodiment. [0039] FIG. 29 is a rear cross-section view of a portion of the decomposition chamber of FIG. 28.

[0040] FIGS. 30-33 are computational fluid dynamic (CFD) simulations showing thermal gradients of exhaust gas flowing through the decomposition chamber of FIG. 1.

[0041] Reference is made to the accompanying drawings throughout the following detailed description. In the drawings, similar symbols typically identify similar components unless context dictates otherwise. The illustrative implementations described in the detailed description, drawings, and claims are not meant to be limiting. Other implementations may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and made part of this disclosure.

DETAILED DESCRIPTION

[0042] Embodiments described herein relate generally to a decomposition chamber for use with aftertreatment systems, and in particular to a U-shaped decomposition chamber that includes a first chamber structured to receive an exhaust gas first portion, and a second chamber positioned outside the first chamber and structured to receive an exhaust gas second portion.

[0043] Aftertreatment systems often include a decomposition chamber or chamber upstream of the SCR system. The reductant is inserted in the decomposition chamber which serves to provide a passage to allow decomposing, mixing and distribution of the reductant with the exhaust gas before the exhaust gas flows into the SCR system. Conventional decomposition chambers have a substantial axial length which requires more packaging space and may also exert a higher pressure drop on the exhaust gas. Furthermore, conventional decomposition chambers experience heat loss due to inefficient thermal management which leads to formation of reductant deposits. [0044] Various embodiments of the decomposition chamber described herein may provide benefits including, for example: (1) thermal management of a temperature of the exhaust gas flowing through the decomposition chamber; (2) providing controlled mass flow split; (3) providing swirl generation in the exhaust gas so as to enhance mixing of a reductant with the exhaust gas; (4) shielding a reductant injector from higher exhaust gas temperatures within the decomposition chamber; (5) enhancing decomposing, mixing and distribution of the reductant with the exhaust gas, thereby reducing reductant deposits; (6) maximizing a uniformity index and reductant evaporation to minimize reductant deposits; and (7) providing a compact packaging which reduces space claim on an aftertreatment system including the decomposition chamber described herein, as well as reduces cost.

[0045] FIGS. 1-6 show various views of a decomposition chamber 100, according to an embodiment. The decomposition chamber 100 comprises a first wall 1, a second wall 3, a third wall, a first chamber 110 formed between the first wall 1 and the second wall 3, and a second chamber 120 formed by the second wall 3 and the third wall 5. The decomposition chamber 100 is structured to receive an exhaust gas (e.g., a diesel exhaust gas) from an engine (e.g., a diesel, a gasoline, a biodiesel, a natural gas, and/or a dual-fuel engine), and allow mixing of the reductant with the exhaust gas before communicating the exhaust gas to an SCR system.

[0046] As best shown in FIG. 5, the first chamber 110 comprises a first plenum 114 defined between the first wall 1 and the second wall 3. The first plenum 114 is positioned along a longitudinal axis A_L of the decomposition chamber 100. The first plenum 114 defines a first plenum internal volume 118. The first plenum 114 may be have any suitable shape, for example spherical, square, rectangular, or any other suitable shape or combination thereof, and may be formed from any suitable material (e.g., metals such as aluminum, stainless steel, alloys, etc.) A first inlet 112 is defined at a first end of the first plenum 114. The first inlet 112 is structured to receive an exhaust gas first portion of the exhaust gas in a first direction perpendicular to the longitudinal axis A_L. For example, the first inlet 112 may be fluidly coupled to an engine exhaust of the engine so as to receive the exhaust gas first portion therefrom. In other embodiments, the first inlet 112 may be oriented at any suitable angle relative to the longitudinal axis, for example any angle between 0 degrees and 360 degrees. [0047] A first reductant insertion port 119 is also defined in the second wall 3 proximate to the first inlet 112. An injector (e.g., the injector 390 shown in FIGS. 10-11), may be fluidly coupled to the first reductant insertion port 119 through a second reductant insertion port 129 defined in a second plenum 124 of the second chamber 120, as described below in further detail, and configured to insert a reductant (e.g., urea, a diesel exhaust fluid, an aqueous urea solution, gaseous urea, ammonia, etc.) in the first plenum internal volume 118. The reductant mixes with the exhaust gas flowing into the first plenum internal volume 118 s as to facilitate

decomposition of constituents of the exhaust gas, for example NOx gases included in the exhaust gas.

[0048] A first outlet 116 is also defined on a second end of the first plenum 114 opposite the first end between the first wall 1 and the second wall 3. The first outlet 116 is structured to allow the exhaust gas to exit the first plenum 114 in a second direction opposite the first direction perpendicular to the longitudinal axis A_L. In other embodiments, the first inlet 112 may be oriented at any suitable angle relative to the longitudinal axis, for example any angle between 0 degrees and 360 degrees. In other words, the decomposition chamber 100 is substantially U-shaped. The first outlet 116 may be fluidly coupled to the SCR system so as to communicate the exhaust gas thereto. In this manner, the decomposition chamber 100 may have a compact size which requires lesser packaging space compared to conventional decomposition chambers, as well as exerts less pressure drop on the exhaust gas as it flows through the first plenum 114. A second flange 4 may be positioned at the outlet and structured to couple the first outlet 116 to an aftertreatment component (e.g., the SCR system)

[0049] In particular embodiments, a plurality of baffles 130 may be positioned on the first inlet 112. The plurality of baffles 130 may be structured to guide the flow of the exhaust gas into the first plenum internal volume 118. By guiding the flow, the plurality of baffles 130 prevent reductant deposits from impacting any aftertreatment component positioned upstream of the first inlet 112 (e.g., a particulate filter). The plurality of baffles 130 may also manage an exhaust gas flow, for example by varying an opening between each of the plurality of baffles 130 and/or an angle of inclination of the plurality of baffles 130, allow a reductant spray to develop, and enable distribution of the reductant deposits uniformly across a width of the first plenum 114. [0050] In some embodiments, a mixer 160 may be positioned within the first plenum internal volume 118 downstream of the first reductant insertion port 119, for example midway within the exhaust gas flow path defined by the first plenum internal volume 118. The mixer 160 may include a cross-vaned mixer comprising a plurality of tabs 162, as shown in FIG. 4.

The mixer 160 is structured to uniformly distribute exhaust gas flow mixed with reductant across a width of the first plenum 114, enable secondary atomization of reductant droplets, prevent recirculation and/or flow separation due to sharp change in exhaust gas flow direction of the exhaust gas first portion as it enters the first plenum 114 from the first inlet 112, and improves flow distribution thereby reducing reductant deposits. The location of the mixer 160 may allow for a spray cone of the reductant to properly develop, and in turn ensures maximum utilization of the mixer 160 for droplet breakup. The mixer 160 may also increase an exhaust gas flow velocity of the exhaust gas first portion, which may shear reductant droplets and enable secondary atomization, and thereby improve reductant evaporation.

[0051] In other embodiments, a diffuser 150 may be positioned in the first plenum internal volume 118 proximate to the first outlet 116. The diffuser 150 comprises a diffuser first end 151 coupled to the second wall 3 and defining a first cross-section. A diffuser second end 153 is coupled to the first outlet 116 and defines a second cross-section larger than the first cross- section. At least a portion of the diffuser 150 proximate to the diffuser second end 153 defines a curvature. For example, a portion of the diffuser 150 may be cylindrical having a constant cross-section extending from the diffuser first end 151 towards the diffuser second end 153. A second portion of the diffuser 150 may flare outwards (e.g., curve outwards or slant outwards) from the diffuser first portion towards the first outlet 116. In other embodiments, the diffuser 150 may be positioned such that a gap exists between the diffuser first end 151 and the second wall 3, for example to allow a portion of the exhaust gas to in the gap so improve uniformity, reduce reductant deposit formation and/or reduce backpressure In particular embodiments, the gap may be in a range of 1 mm to 5 mm (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 mm, inclusive of all ranges and values therebetween).

[0052] A diffuser opening 155 is defined in the diffuser 150 proximate to the second end of the first plenum 114. The diffuser opening 155 is structured to allow the exhaust gas first portion flowing around the diffuser 150 to enter into the diffuser 150 and exit through the first outlet 116. Positioning of the diffuser 150 proximate to the first outlet 116 locates the diffuser 150 just upstream the SCR system which may be fluidly coupled to the first outlet 116. The diffuser 150 increases the distance travelled by the exhaust gas first portion, thereby increasing mixing of the reductant with the exhaust gas, enhancing evaporation of reductant droplets, and may further facilitate atomization of reductant droplets by increasing the turbulence and flow velocity of the exhaust gas first portion. In particular embodiments, the diffuser 150 may be configured to allow all of the exhaust gas including the exhaust gas first portion, an exhaust gas second portion flowing through a second plenum 118, and an exhaust gas third portion flowing through a third plenum 122 (described below in further detail herein) therethrough.

[0053] As the exhaust gas first portion flows around the diffuser 150 towards the first outlet 116, opposing stream of the exhaust gas first portion flow around the diffuser 150 and rejoin on entering the diffuser 150 through the diffuser opening 155. The opposing streams collide within the diffuser 150 which further enhances atomization of the reductant droplets, and may also elevate the exhaust gas flow. In various embodiments, the diffuser 150 may include openings, perforations, slots, louvers, etc. to increase uniformity of exhaust gas flow towards the SCR system and reduce flow restriction. Positioning and location of the openings or perforations may be positioned to change the flow velocity vectors to enhance mixing, the size of the opening may be varied to achieve optimal flow velocities, and/or the shape of the diffuser 150 may be changed or rotated to decrease or increase the diffuser opening 155, as described in further detail below herein.

[0054] In still another embodiment, a perforated plate 140 may be positioned at the first outlet 116. The perforated plate 140 may prevent any reductant deposits from flowing into the SCR system. Furthermore, the perforated plate 140 may also serve as a secondary flow conditioning device so as to manage flow restriction, distribution, uniformity, and/or reductant droplet distribution. While FIG. 1 shows the perforated plate 140 as including a straight perforated plate, in other embodiments, the perforated plate 140 may have a concave or convex shape so as to produce a desired flow of the exhaust gas first portion. Furthermore, the perforated plate 140 may have a uniform or non-uniform pattern of the perforations included therein. [0055] The decomposition chamber 100 also comprises a second chamber 120 coupled to the first chamber 110. The second chamber 120 comprises a second plenum 124 defined between the second wall 3 and the third wall 5 and positioned along the longitudinal axis A_L of the decomposition chamber 100 such that the second plenum 124 is positioned around at least a portion of the first plenum 114. The second plenum 124 defines a second plenum internal volume 128, and a second inlet 121 defined between the second wall 3 and the third wall 5 to the first inlet 112. The second inlet 121 is structured to receive an exhaust gas second portion of the exhaust gas. The exhaust gas second portion flows into the second plenum 124 around the first plenum 114 so as to maintain a temperature of the exhaust gas first portion flowing through the first plenum internal volume 118.

[0056] Expanding further, the second chamber 120 serves as a jacket positioned around at least a portion of the first chamber 110. The first inlet 112 of the first plenum 114, and the second inlet 121 of the second plenum 124 are positioned adjacent to each other and fluidly coupled to a source of the exhaust gas, for example to the engine exhaust. In some

embodiments, a first flange 2 may be coupled to each of the first inlet 112 and the second inlet 121 so as to provide a single fluid coupling with the engine exhaust and fluidly couple each of the first inlet 112 and the second inlet 121 to the engine exhaust.

[0057] As the exhaust gas enters the decomposition chamber 100, the exhaust gas splits into the exhaust gas first portion flowing into the first inlet 112, and an exhaust gas second portion flowing into the second inlet 121 towards the second plenum internal volume 128. The exhaust gas second portion enables thermal management of the first plenum 114 by keeping the first plenum sidewall at a desired temperature. This reduces reductant deposits particularly in areas where the reductant impinges on the first plenum sidewall.

[0058] In some embodiments, a plurality of guiding baffles 6 may be positioned in the second plenum 124, as shown in FIG. 4. The plurality of guiding baffles 6 may facilitate uniform spreading of the exhaust gas second portion within the second plenum internal volume 128 so as to keep the entire second plenum internal volume 128, or specific areas therewithin at a desired temperature. In still other embodiments, a plurality of louvers 113 may be defined on the second wall 3 in the first plenum 114 downstream of the first inlet 112, and upstream of the mixer 160. The plurality of louvers 113 fluidly couple the second plenum 124 to the first plenum 114.

[0059] The plurality of guiding baffles 6 may guide the exhaust gas second portion flow from the sides of the second plenum 124 to the plurality of louvers 113. In particular embodiments, the plurality of louvers 113 may comprise a plurality of perforations or perforated cones as shown in FIGS. 1-3, and 5-6. Positioning of the louvers 113 on the first plenum sidewall creates a bed of the exhaust gas second portion on the first plenum sidewall proximate to the first reductant insertion port 119, which may decrease impingement of the reductant on the first plenum sidewall. Since the exhaust gas second portion does not include any reductant, upstream introduction thereof may increase mixing of the reductant with the exhaust gas, facilitate evaporation and thereby, improve uniformity.

[0060] A quantity and/or open areas of the plurality of louvers 113 may be adjusted to adjust flow restriction, and/or impingement. Furthermore, the location of the plurality of louvers 113 may be adjusted based on impingement zones and/or mixing requirements. FIGS. 16 -17 show a decomposition chamber 400 according to another embodiment. A plurality of louvers 413 are defined on a first plenum sidewall of a first plenum of a first chamber 410 of the decomposition chamber 400, fluidly couple a second plenum of a second chamber 420 to a first plenum of the first chamber 410 via a plurality of openings 413a defined in the first plenum sidewall. The plurality of louvers 413 comprise longitudinal louvers positioned perpendicular to a longitudinal axis of the decomposition chamber 400 on the first plenum sidewall.

[0061] In other embodiments, slots, diverters, perforated cones, or any other features may defined on the first plenum sidewall for fluidly coupling the second plenum 124 thereto.

Furthermore, the second plenum internal volume 128, and/or a gap between the first plenum sidewall and the second plenum sidewall may be varied to adjust reductant insertion rate, and/or exhaust gas flow rates.

[0062] As previous described, the second reductant insertion port 129 is defined in the second plenum 124 proximate to the first reductant insertion port 119 as shown in FIGS.2-3 and 5-7. For example, the first reductant insertion port 119 and the second reductant insertion port 129 may be axially aligned. An injector mounting plate 115 may be positioned in the second reductant insertion port 129, and structured to mount an injector (e.g., the injector 390 shown in FIGS. 10-11) thereon. The injector mounting plate 115 defines an aperture 117 structured to allow inserting of the reductant into the first plenum internal volume 118.

[0063] In some embodiments, the decomposition chamber 100 also comprises a third plenum 122. Referring also now to FIGS. 14 and 15, a U-shaped divider 111 may be positioned in the second inlet 121 around the first reductant insertion port 119 and the second reductant insertion port 129, such that the divider 111 defines the third plenum 122 around the first reductant insertion port 119 and the second reductant insertion port 129. The third plenum 122 is structured to receive an exhaust gas third portion and to thermally isolate the injector fluidly coupled to the first reductant insertion port 119 and the second reductant insertion port 129 from the first plenum 114.

[0064] In particular embodiments, the injector inserts the reductant into the third plenum 122. The exhaust gas third portion flowing into the third plenum 122 may assist reductant flow into the first plenum internal volume 118 (i.e., provide exhaust assisted reductant insertion), ensuring proper reductant flow velocities so as to help develop the reductant spray and facilitate penetration into the exhaust gas first portion. Furthermore, flow of the exhaust gas third portion into the third plenum 122 may provide a thermal shield for the injector from the higher temperature of the first plenum 114 and maintain a temperature of an injector tip (e.g., a reductant insertion nozzle) below a temperature threshold. The exhaust gas third portion may also carry away reductant droplets accumulated around the injector tip, thereby avoiding reductant deposits from forming on the injector tip.

[0065] In still other embodiments, the first reductant insertion port 119 may have a larger cross-section than a cross-section of the second reductant insertion port 129, and may be inclined at an angle relative to the longitudinal axis A_L. The larger cross-section of the first reductant insertion port 119 and inclination thereof may facilitate larger flow rate and increase reductant insertion velocity assisted by the exhaust gas third portion flow. [0066] The second chamber 120 may have structures or features for mounting the injector mounting plate 115 and/or the injector. In one embodiment shown in FIGS. 1-7, the second chamber 120 may comprise a recess 123 defined by the second plenum sidewall around the second reductant insertion port 129. The recess 123 comprises a recess base 125 in which the second reductant insertion port 129 is defined. The recess 123 may be structured such that the injector positioned on the injector mounting plate 115 is at least partially surrounded by a recess sidewall of the recess 123 so as to protect the injector from physical damage. The recess 123 reduces a distance between the point of reductant insertion through the second reductant insertion port 129, and the first reductant insertion port 119, so as to facilitate exhaust gas assisted reductant insertion via the exhaust gas third portion.

[0067] FIGS. 8 shows a top perspective view, and FIG. 9 shows a side cross-section view of a portion of a decomposition chamber 200, according to another embodiment. The

decomposition chamber 200 comprises a first chamber 210 having a first plenum 214, and a second chamber 220 having a second plenum 224. A first reductant insertion port 219 is defined in the first plenum 214. The second plenum 224 comprises an injector mount portion 225 which includes a flattened surface for mounting the injector. A second reductant insertion port 229 is defined in the injector mount portion 225.

[0068] The injector may be mounted at any suitable location proximate to the first inlet 112 of the decomposition chamber 100. According to a particular embodiment shown in FIG. 10, a decomposition chamber 300a comprises a second chamber 320a including a second plenum 324a. The second plenum 324a defines an injector mount portion 325a which is relatively flat. An injector 390 is mounted on the injector mount portion 325a, which is positioned such that the injector is axially aligned with the longitudinal axis A_L.

[0069] According to another embodiment shown in FIG.11, a decomposition chamber 300b comprises a second chamber 320b including a second plenum 324b. The second plenum 324b also defines a flat injector mount portion 325b. However, the second plenum 324b is located such that the injector 390 mounted thereon, is inclined or oriented at an angle a (e.g., in the range of + 90 degrees) with respect to the longitudinal axis A_L. Inclining the injector 390 with respect to a flow direction of the exhaust gas may facilitate smoothening of the exhaust gas flow, and/or avoid reductant deposit generation on the first plenum sidewall or corners thereof. Furthermore, the flattened injector mount portion 225, 325a/b may also reduce the space occupied by the decomposition chamber 100, 300a/b when packaged with an aftertreatment system.

[0070] In various embodiments, the decomposition chamber 100 or any other

decomposition chamber described herein may have smooth corners for ease of packaging. For example, FIG. 12 shows a side view and FIG. 13 shows a rear view of the decomposition chamber 100. The second plenum sidewall of the second plenum 124 includes smooth rounded corners (e.g., the second chamber 120 is molded to have the smooth rounded corners), which may provide ease of handling and facilitate package.

[0071] As described previously, the diffuser 150 may include open areas, perforations, slots, louvers, etc. to increase uniformity of exhaust gas flow towards the SCR system and reduce flow restriction. FIG. 18 shows a side cross section view of a decomposition chamber 500 according to an embodiment, and FIG. 19 shows an enlarged view of a portion thereof. The decomposition chamber 500 comprises a first chamber 510 and a second chamber 520. The first chamber 510 comprises a first inlet 512, a first plenum 514 defining a first plenum internal volume 518, and a first outlet 516.

[0072] A diffuser 550 is positioned within the first plenum internal volume 518. The diffuser 550 comprises a diffuser first end 551 which defines a first cross-section. The diffuser first end 551 is positioned such that a gap exists between the first plenum sidewall of the first plenum 514 and the diffuser first end 551. In particular embodiments, the gap may be in a range of 1 mm to 5 mm (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 mm, inclusive of all ranges and values therebetween). A diffuser second end 553 is coupled to the first outlet 516 and defines a second cross-section larger than the first cross-section. A diffuser first portion of the diffuser 550 is cylindrical having a constant cross-section extending from the diffuser first end 551 towards the diffuser second end 553. A diffuser second portion of the diffuser 550 curves outwards towards the first outlet 516. [0073] A plurality of first perforations 557 are defined on the diffuser first portion, and may span less than half a circumference of the diffuser first portion. The plurality of first perforations 557 allow for at least a portion of the exhaust gas first portion flowing towards the diffuser 550 to enter the diffuser 550 therethrough, which may further increase flow uniformity, adjust flow velocity and/or enhance mixing of the reductant with the exhaust gas first portion.

[0074] In particular embodiments, a first plenum sidewall of the first plenum 514 proximate to the first outlet 516 may include a first plenum sidewall curved portion 516a directing the exhaust gas first portion flow towards the first outlet 516. The first plenum sidewall curved portion 516a may create a smoother transition of two opposite swirls of the exhaust gas first portion flowing around the diffuser 550 towards the first outlet 516, eliminating recirculation and project the exhaust gas first portion flow towards the first outlet 516.

[0075] FIG. 20 shows a side cross section view, and FIG. 21 shows an enlarged view of a portion of a decomposition chamber 600 according to another embodiment. The decomposition chamber 600 comprises a first chamber 610 and a second chamber 620. The first chamber 610 comprises a first plenum 614 defining a first plenum internal volume 618, and a first outlet 616.

[0076] A diffuser 650 is positioned within the first plenum internal volume 618. The diffuser 650 comprises a diffuser first end 651 which defines a first cross-section. The diffuser first end 651 is positioned such that a gap exists between the first plenum sidewall of the first plenum 614 and the diffuser first end 651. In particular embodiments, the gap may be in a range of 1 mm to 5 mm (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 mm, inclusive of all ranges and values therebetween). . A diffuser second end 653 is coupled to the first outlet 616 and defines a second cross-section larger than the first cross-section. The diffuser 650 defines a diffuser opening 655. A diffuser first portion of the diffuser 650 is cylindrical having a constant cross- section extending from the diffuser first end 651 towards the diffuser second end 653. A diffuser second portion of the diffuser 650 flares outwards at an angle from the diffuser first portion towards the first outlet 616.

[0077] A plurality of first perforations 657 are defined on the diffuser first portion, and may span less than half a circumference of the diffuser first portion. A plurality of second perforations 659 are also defined on the diffuser second portion. The plurality of second perforations 659, along with the plurality of first perforations 657 may further increase flow uniformity, adjust flow velocity and/or enhance mixing of the reductant with the exhaust gas first portion.

[0078] A diffuser baffle 672 is positioned within the diffuser 650 and extends from the first plenum sidewall towards the first outlet 616. As shown in FIG. 21, the diffuser baffle 672 is positioned horizontally within the diffuser 650. The diffuser baffle 672 has a width which is less than a diffuser width of the diffuser 650 and has a length less than a diffuser length of the diffuser 650. The diffuser baffle 672 may redirect a bypassed exhaust gas first portion flow from the diffuser 650 so as to increase uniformity of the exhaust gas first portion flow towards the first outlet 616. The diffuser baffle 672 may also include perforations, slots, louvers or have no openings defined therein. Moreover, while FIGS.20-21 show the diffuser baffle 672 as being planar, in other embodiments, the diffuser baffle 672 may be concave, convex, curved and/or have any other suitable shape or size.

[0079] In particular embodiments, a first plenum curved plate 674 is positioned on a first plenum sidewall of the first plenum 614 proximate to the first outlet 616. The first plenum curved plate 674 is inclined at a downward angle from the first plenum sidewall towards the first outlet 616, and is structured to direct the exhaust gas first portion flow towards the first outlet 616. The first plenum curved plate 674 may create a smoother transition of two opposite swirls of the exhaust gas first portion flowing around the diffuser 650, by augmenting the natural flow profile of the two opposing swirl streams. A profile of the first plenum curved plate 674 may be structured to help sustain the swirl by separating the two swirl stream of the exhaust gas fist portion, and facilitate projecting the exhaust gas first portion flow and reductant droplets towards the first outlet 616 so as to increase uniformity.

[0080] FIG. 22 shows a side cross section view, and FIG. 23 shows an enlarged view of a portion of a decomposition chamber 700 according to yet another embodiment. The

decomposition chamber 700 comprises a first chamber 710 and a second chamber 720. The first chamber 710 comprises a first plenum 714 defining a first plenum internal volume 718, and a first outlet 716. Furthermore, the second chamber 720 comprises a second plenum 724 having a second plenum second end 726 proximate to the first outlet 716.

[0081] A diffuser 750 is positioned within the first plenum internal volume 718 and comprises a diffuser first end 751 defining a first cross-section. The diffuser first end 751 is positioned such that a gap exists between the first plenum sidewall of the first plenum 714 and the diffuser first end 751. In particular embodiments, the gap may be in a range of 1 mm to 5 mm (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 mm, inclusive of all ranges and values therebetween). A diffuser second end 753 is coupled to the first outlet 716 and defines a second cross-section larger than the first cross-section. A diffuser first portion of the diffuser 750 is cylindrical having a constant cross-section extending from the diffuser first end 751 towards the diffuser second end 753. A diffuser second portion of the diffuser 750 flares outwards at an angle from the diffuser first portion towards the first outlet 716.

[0082] A plurality of longitudinal slots 757 are defined on the diffuser first portion, and extend axially from the diffuser first end 751 towards the diffuser second portion. A plurality of second perforations 759 are also defined on the diffuser second portion, as described previously with respect to the diffuser 750. A diffuser baffle 772 is positioned within the diffuser 750, and may be substantially similar in structure and function to the diffuser baffle 772.

[0083] A first plenum curved plate 774 is positioned on a first plenum sidewall of the first plenum 714 proximate to second plenum second end 726. The first plenum curved plate 774 is inclined at a downward angle from the first plenum sidewall towards the first outlet 716. The first plenum curved plate 774 defines a plurality of apertures 775 fluidly coupling the second plenum 724 to the first plenum 714 at the second plenum second end 726. At least a portion of the exhaust gas second portion may enter the first plenum internal volume 718 through the plurality of apertures 775 such that the first plenum curved plate 774, in addition to directing the exhaust gas flow towards the first outlet 716, may also increase shear on the first plenum sidewall via the portion of the exhaust gas second portion, and propel the reductant droplets towards the first outlet 716. [0084] FIG. 24 shows a side cross section view, and FIG. 25 shows an enlarged view of a portion of a decomposition chamber 800 according to another embodiment. The decomposition chamber 800 comprises a first chamber 810 and a second chamber 820. The first chamber 810 comprises a first plenum 814 defining a first plenum internal volume 818, and a first outlet 816.

[0085] A diffuser 850 is positioned within the first plenum internal volume 818. The diffuser 850 comprises a diffuser first end 851 which defines a first cross-section. The diffuser first end 851 is positioned such that a gap exists between the first plenum sidewall of the first plenum 814 and the diffuser first end 851. In particular embodiments, the gap may be in a range of 1 mm to 5 mm (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 mm, inclusive of all ranges and values therebetween). A diffuser second end 853 is coupled to the first outlet 816 and defines a second cross-section larger than the first cross-section. The diffuser 850 comprises a diffuser first portion and a diffuser second portion as described previously with respect to the diffuser 650, 750, and defines a diffuser opening 855 which is larger than the diffuser opening 655 of the diffuser 650.

[0086] Furthermore, a plurality of first perforations 857 are defined on the diffuser first portion. The plurality of first perforations 857 have a larger diameter and more densely distributed than the plurality of first perforations 557, 657 of the diffuser 550, 650. Moreover, the plurality of first perforations 857 span more than half of a circumference of the diffuser first portion.

[0087] A plurality of second perforations 859 are also defined on the diffuser second portion. The plurality of second perforations 859 have a larger diameter and are more densely distributed than the plurality of second perforations 859 of the diffuser 850. A diffuser baffle 872 is positioned within the diffuser 850 and extends from a first plenum sidewall of the first plenum 814 towards the first outlet 816. Moreover, a first plenum curved plate 874 is positioned on a first plenum sidewall of the first plenum 814, and is inclined at downward angle from the first plenum sidewall towards the first outlet 816.

[0088] FIG. 26 shows a side cross section view, and FIG. 27 shows an enlarged view of a portion of a decomposition chamber 900, according to still another embodiment. The decomposition chamber 900 comprises a first chamber 910 and a second chamber 920. The first chamber 910 comprises a first plenum 914 defining a first plenum internal volume 918, and a first outlet 916. A diffuser 950 is positioned within the first plenum internal volume 918 and defines a diffuser opening 955 which is smaller than the diffuser openings 655 and 855 of the diffusers 650 and 850, respectively. A first plenum curved plate 974 is positioned on a first plenum sidewall of the first plenum 914. The first plenum curved plate 974 is axially aligned with the first outlet 916, and extends from a first plenum sidewall of the first plenum 914 towards the first outlet 916.

[0089] FIG. 28 shows a side cross section view, and FIG. 29 shows an enlarged view of a portion of a decomposition chamber 1000, according to another embodiment. The

decomposition chamber 1000 comprises a first chamber 1010 and a second chamber 1020. The first chamber 1010 comprises a first plenum 1014 defining a first plenum internal volume 1018, and a first outlet 1016.

[0090] A diffuser 1050 is positioned within the first plenum internal volume 1018. The diffuser 1050 comprises a diffuser first end 1051 coupled to a first plenum sidewall and a diffuser second end 1053 which is coupled to the first outlet 1016. The diffuser 1050 comprises a diffuser first portion and a diffuser second portion as described previously with respect to the diffuser 650, 750. A plurality of first perforations 1057 are defined on the diffuser first portion.

[0091] A diffuser baffle 1072 is positioned within the diffuser 1050 and extends from a first plenum sidewall of the first plenum 1014 towards the first outlet 1016. The diffuser baffle 1072 has a diffuser baffle length less than half a diffuser first portion length of the diffuser first portion. Furthermore, the diffuser baffle 1072 has a width which is about a width of a segment of the diffuser baffle first portion within which the diffuser baffle 1072 is positioned. A first plenum curved plate 1074 is positioned on a first plenum sidewall of the first plenum 1014, and is inclined at downward angle from the first plenum sidewall towards the first outlet 1016.

[0092] FIGS. 30-33 are CFD simulations showing velocity profiles of the exhaust gas first portion, the exhaust gas second portion and the exhaust gas third portion through the decomposition chamber 100. As apparent from simulations, the decomposition chamber 100 is structured such that the exhaust gas first portion accelerates in the first plenum and has a maximum exhaust gas first portion velocity at the first outlet, and has a high flow distribution index (FDI) at the first outlet as highlighted in FIG. 33.

[0093] It should be noted that the term“example” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples,

representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

[0094] The terms“coupled,” and the like as used herein mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.

[0095] It is important to note that the construction and arrangement of the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements; values of parameters, mounting arrangements; use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Additionally, it should be understood that features from one embodiment disclosed herein may be combined with features of other embodiments disclosed herein as one of ordinary skill in the art would understand. Other substitutions, modifications, changes, and omissions may also be made in the design, operating conditions, and arrangement of the various exemplary embodiments without departing from the scope of the present embodiments.

[0096] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any embodiments or of what may be claimed, but rather as descriptions of features specific to particular implementations of particular embodiments. Certain features described in this specification in the context of separate implementations can also be implemented in combination in a single implementation.

Conversely, various features described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination.

Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a

subcombination or variation of a subcombination.

Claims

WHAT IS CLAIMED IS:

1. A decomposition chamber for an aftertreatment system, the decomposition chamber comprising:

a first wall;

a second wall; and

a third wall;

wherein a first plenum is defined between the first wall and the second wall, the first plenum positioned along a longitudinal axis of the decomposition chamber, the first plenum defining a first plenum internal volume, a first inlet defined at a first end of the first plenum between the first wall and the second wall, the first inlet structured to receive an exhaust gas first portion of an exhaust gas in a first direction perpendicular to the longitudinal axis, and a first outlet defined on a second end of the first plenum opposite the first end between the first wall and the second wall, the first outlet structured to allow the exhaust gas first portion to exit in a second direction opposite the first direction perpendicular to the longitudinal axis; and wherein a second plenum is defined between the second wall and the third wall, the second plenum position along the longitudinal axis of the decomposition chamber such that the second plenum is positioned around at least a portion of the first plenum, the second plenum defining a second plenum internal volume, and a second inlet defined between the second wall and third wall to the first inlet, the second inlet structured to receive an exhaust gas second portion of the exhaust gas, the exhaust gas second portion flowing into the second plenum so as to flow around the first plenum and maintain a temperature of the exhaust gas first portion flowing through the first plenum.

2. The decomposition chamber of claim 1, further comprising a plurality of louvers defined on the second wall in the first plenum, the plurality of louvers fluidly coupling the second plenum to the first plenum.

3. The decomposition chamber of claim 2, further comprising a mixer positioned within the first plenum downstream of the plurality of louvers.

4. The decomposition chamber of claim 2, further comprising a perforated plate positioned at the first outlet.

5. The decomposition chamber of claim 1, further comprising a plurality of guiding baffles positioned in the second plenum and configured to uniformly spread exhaust gas second portion within the second plenum internal volume.

6. The decomposition chamber of claim 1, further comprising:

a first reductant insertion port defined in the second wall to the first inlet;

a second reductant insertion port defined in the third wall to the first reductant insertion port; and

a U-shaped divider positioned in the second inlet around the first reductant insertion port and the second reductant insertion port so as to define a third plenum, the third plenum structured to receive an exhaust gas third portion and to thermally isolate an injector fluidly coupled to the first reductant insertion port and the second reductant insertion port from the first plenum.

7 The decomposition chamber of claim 6, wherein the first reductant insertion port and the second reductant insertion port are oriented so as to axially align the injector with the longitudinal axis of the decomposition chamber.

8. The decomposition chamber of claim 6, wherein the first reductant insertion port and the second reductant insertion port are oriented at a non-zero angle with respect to the longitudinal axis such that the injector is inclined at the non-zero angle with respect to the longitudinal axis.

9. The decomposition chamber of claim 1, further comprising a plurality of baffles positioned at the first inlet.

10. The decomposition chamber of claim 1, further comprising:

a diffuser positioned in the first plenum internal volume, the diffuser comprising: a diffuser first end positioned proximate to the second wall and defining a first cross-section;

a diffuser second end coupled to the first outlet and defining a second cross- section larger than the first cross-section, at least a portion of the diffuser to the diffuser second end defining a curvature; and

an opening defined in the diffuser to the second end of the first plenum, the opening structured to allow the exhaust gas first portion flowing around the diffuser to enter into the diffuser and exit through the first outlet.

11. The decomposition chamber of claim 10, wherein the diffuser first end is coupled to the second wall.

12. The decomposition chamber of claim 10, further comprising a diffuser baffle positioned within the diffuser.

13. The decomposition chamber of claim 10, wherein the diffuser comprises a diffuser first portion extending from the diffuser first end towards the diffuser second end and having a constant cross-section, and a diffuser second portion continuous with the diffuser first portion towards the second end and defining the curvature.

14. The decomposition chamber of claim 13, wherein a plurality of first perforations are defined in the diffuser first portion.

15. The decomposition chamber of claim 14, wherein a plurality of second perforations are defined in the diffuser second portion.

16. The decomposition chamber of claim 10, wherein a first plenum sidewall of the first plenum proximate to the first outlet includes a first plenum sidewall curved portion configured to direct the exhaust gas first portion towards the first outlet.

17. The decomposition chamber of claim 10, wherein a first plenum curved plate is positioned on a first plenum sidewall proximate to the first outlet, the first plenum curved plate being inclined at a downward angle from the first plenum sidewall towards the first outlet.

18. The decomposition chamber of claim 15, wherein the first plenum curved plate defines a plurality of apertures fluidly coupling the second plenum to the first plenum.

19. A decomposition chamber for an aftertreatment system, the decomposition chamber comprising:

a first wall;

a second wall; and

a third wall;

wherein a first plenum is defined between the first wall and the second wall, the first plenum defining a first plenum internal volume, a first inlet defined at a first end of the first plenum between the first wall and the second wall, and a first outlet defined on a second end of the first plenum opposite the first end between the first wall and the second wall; and

wherein a second plenum is defined between the second wall and the third wall, the second plenum is positioned around at least a portion of the first plenum, the second plenum defining a second plenum internal volume, and a second inlet defined between the second wall and third wall to the first inlet, the second inlet structured to receive an exhaust gas second portion of the exhaust gas, the exhaust gas second portion flowing into the second plenum so as to flow around the first plenum and maintain a temperature of the exhaust gas first portion flowing through the first plenum.

20. The decomposition chamber of claim 19, further comprising a plurality of baffles positioned at the first inlet.

21. The decomposition chamber of claim 19, further comprising a plurality of louvers defined on the second wall in the first plenum, the plurality of louvers fluidly coupling the second plenum to the first plenum.

22. The decomposition chamber of claim 21, further comprising a mixer positioned within the first plenum downstream of the plurality of louvers.

23. The decomposition chamber of claim 21, further comprising a perforated plate positioned at the first outlet.

24. The decomposition chamber of claim 21, further comprising a plurality of guiding baffles positioned in the second plenum and configured to uniformly spread the exhaust gas second portion within the second plenum internal volume, the plurality of guiding bafflers further configured to guide the exhaust gas second portion from sides of the second plenum towards the plurality of louvers.

25. The decomposition chamber of claim 19, further comprising:

a first reductant insertion port defined in the second wall to the first inlet;

26. The decomposition chamber of claim 19, further comprising:

a diffuser second end coupled to the first outlet and defining a second cross- section larger than the first cross-section, at least a portion of the diffuser to the diffuser second end defining a curvature; and an opening defined in the diffuser to the second end of the first plenum, the opening structured to allow the exhaust gas first portion flowing around the diffuser to enter into the diffuser and exit through the first outlet.

27. The decomposition chamber of claim 26, wherein the diffuser first end is coupled to the second wall.

28. The decomposition chamber of claim 26, further comprising a diffuser baffle positioned within the diffuser.

29. The decomposition chamber of claim 28, wherein the diffuser baffle has a length and width, the length and width being less than a diffuser length and diffuser width of the diffuser, respectively.

30. The decomposition chamber of claim 26, wherein the diffuser comprises a diffuser first portion extending from the diffuser first end towards the diffuser second end and having a constant cross-section, and a diffuser second portion continuous with the diffuser first portion towards the second end and defining the curvature, wherein a plurality of first perforations are defined in the diffuser first portion.

31. The decomposition chamber of claim 30, wherein the plurality of first perforations span less than half of a circumference of the diffuser first portion.

32. The decomposition chamber of claim 30, wherein a plurality of second perforations are defined in the diffuser second portion.

33. The decomposition chamber of claim 30, wherein a plurality of longitudinal slots are defined on the diffuser first portion, the plurality of longitudinal slots extending axially from the diffuser first end towards the diffuser second portion.

34. The decomposition chamber of claim 26, wherein a first plenum curved plate is positioned on a first plenum sidewall proximate to the first outlet, the first plenum curved plate inclined at a downward angle from the first plenum sidewall towards the first outlet.

35. The decomposition chamber of claim 34, wherein the first plenum curved plate defines a plurality of apertures fluidly coupling the second plenum to the first plenum.