Exhaust gas-assisted pipe assembly

Abstract

Exhaust-assisted pipe assembly (210), comprising an outer part (212) having an opening (214) for receiving metered reducing agent from a metering module (290), and an inner part (220) arranged within the outer part (212), wherein the inner part defines a main flow path for receiving a first portion of a fluid from an upstream source, and the inner part and the outer part jointly define a first cavity (230) for a first flow path between the inner part and the outer part, and a second cavity (240) for a second flow path between the inner part and the outer part, wherein the first cavity and the second cavity are separated by a longitudinally extending wall (250) connecting the outer part to the inner part, the first flow path of the first cavity (230) being configuredto receive metered reducing agent from the metering module (290) through the opening (214) of the outer part (212) and to direct a second part of the fluid from the upstream source past the opening (214) to receive metered reducing agent and into the first main flow path in order to increase the momentum of the metered reducing agent in the main flow path, wherein the second flow path of the second cavity (240) is configured to direct a third part of the fluid from the upstream source to the metered reducing agent in order to decrease the momentum of the metered reducing agent in the main flow path.

Description

In internal combustion engines, such as a diesel engine or natural gas engine, nitrogen oxide (NO x)- compounds may be emitted in the exhaust gas of a vehicle. To reduce NO x- emissions, a selective catalytic reduction (SCR) process may be implemented to convert the NO x- compounds to more neutral compounds such as diatomic nitrogen, water, or carbon dioxide using a catalyst and a reducing agent. The catalyst may be contained in a catalyst chamber of an exhaust system. Typically, a reductant such as anhydrous ammonia, aqueous ammonia or urea is introduced into the exhaust stream prior to the catalyst chamber. To introduce the reductant into the exhaust stream for the SCR process, an SCR system may dose or otherwise introduce the reductant through a dosing module that evaporates or sprays the reductant into an exhaust pipe of the exhaust system upstream of the catalyst chamber. In some implementations, the dosing module is disposed in an elbow of the exhaust system. Such an arrangement of the dosing module may allow the use of a low speed dosing module and small diameter droplets by using the exhaust stream to disperse the injected reductant. However, such a configuration may be less desirable, as some configurations may not be capable of accommodating an angular exhaust component.A further exhaust gas treatment device is known from DE 10 2009 031 502 A1. Exemplary embodiments of DE 10 2009 031 502 A1 are directed to a device and a method for controlling fluid flow through a line of an exhaust system for an engine, in particular upstream of an exhaust gas treatment device. In one embodiment, a fluid flow control device is provided for receiving and directing exhaust gas from an engine toward an exhaust treatment device. The fluid flow control device includes a nozzle disposed in an exhaust passage of the engine. The nozzle includes an inlet opening and an outlet opening for forming a first flow path through the nozzle. The nozzle is spaced from the exhaust conduit to form a second flow path between the nozzle and the exhaust conduit. The fluid flow control device also includes an injector disposed adjacent the nozzle. The injector may be oriented to direct a pressurized fluid to the first or second flow path.WO 2009 / 024 815 A2 discloses an exhaust system having a flow path comprising an emission control device in a first portion of the flow path, a liquid injector arranged to inject a liquid into a second portion of the flow path after the first portion, and a catalytic emission control device in a third portion of the one catalytic emission control device in a third portion of the flow path after the second portion, the second portion defining a collection chamber that serves to collect exhaust gas once it leaves the emission control device, the collection chamber defining the exhaust gas into a contraction region of the second portion of the second portion, a collection chamber that serves to collect the exhaust gas after it has exited the emission control device, the collection chamber guiding the exhaust gas into a constriction region of the second portion, wherein the constriction region comprises a tube, the part of which projects into the collecting chamber.A further exhaust system is known from DE 10 2010 035 311 A1. A decoupling element, in particular for exhaust gas systems, for use with an injection device for injecting a reducing agent, such as urea, having an undulated metal bellows and a flow-guiding element arranged within the bellows, the outer diameter of which element is smaller than the inner diameter of the bellows. In this case, it is provided that the flow-guiding element separates the interior of the bellows into an inner core flow path for a core flow of the exhaust gas flow and an outer jacket flow path for a jacket flow of the exhaust gas flow. Furthermore, a method is described, whereby exhaust gas flowing in an exhaust gas flow flows divided into a core flow and a sheath flow by a flow-guiding element arranged with a finite radial distance within the bellows, whereby wetting of the bellows and thus deposition of urea within the bellows shafts is avoided.More specifically, the present invention relates to an exhaust assisted pipe assembly according to claim 1, an exhaust system comprising an exhaust assisted pipe assembly according to claim 6, and a method of assembling an exhaust system comprising an exhaust assisted pipe assembly according to claim 9.Claim 1 relates to an exhaust assisted pipe assembly comprising an outer part having an opening for receiving a dosed reducing agent from a dosing module and an inner part disposed within the outer part. The inner portion defines a main flow path for receiving a first portion of a fluid from an upstream source, and the inner portion and the outer portion collectively define a first flow path and a second flow path. The first flow path is configured to direct a second portion of the fluid from the upstream source past the metered reductant receiving opening and into the first main flow path to increase the momentum of the metered reductant into the main flow path. The second flow path is configured to direct a third portion of the fluid from the upstream source to the dosed reductant to reduce the momentum of the dosed reductant in the main flow path.Preferred embodiments and developments of an exhaust-gas-assisted pipe assembly according to claim 1 are the subject matter of claims 2 to 5.In some implementations, the fluid is an exhaust gas.In some implementations, the inner portion may be a tubular member.In some implementations, the inner portion may include a first opening and a second opening. The first opening allows the second portion of the fluid to flow from the first flow path into the main flow path, and the second opening allows the third portion of the fluid to flow from the second flow path into the main flow path.In some implementations, at least a portion is positioned relative to the opening of the outer portion such that the metered reductant flows from the metering module through the first opening into the main flow path.In some implementations, the second opening is oriented upstream, downstream of the first opening, or opposite the first opening relative to the first opening.In some implementations, the outer portion and the inner portion comprise straight tubular portions.In some implementations, an outlet end of the inner portion is connected to the outer portion. The inner part, the outer part, and the outlet end may define a first cavity for the first flow path, and the outlet end of the inner part connected to the outer part blocks the second part of the fluid flowing along the first flow path from flowing out of an outlet end of the first cavity. The inner part, the outer part, and the outlet end define a second cavity for the second flow path, and the outlet end of the inner part connected to the outer part blocks the third part of the fluid flowing along the second flow path from flowing out of an outlet end of the second cavity.In some implementations, the third portion of the fluid flowing along the second flow path increases a temperature of a surface of the inner portion.In some implementations, the first flow path and the second flow path are separated by one or more walls extending between the outer portion and the inner portion.Claim 6 relates to an exhaust system comprising a first part of an exhaust system receiving exhaust gas, a second part of the exhaust system and an exhaust assisted pipe assembly connected to an upstream end of the first part of the exhaust system to receive the exhaust gas from the first part and connected at a downstream end to the second part of the exhaust system. The exhaust assisted pipe assembly includes an outer portion having an opening for receiving a dosed reductant from a dosing module and an inner portion disposed within the outer portion. The inner portion defines a main flow path through the inner portion for receiving a first portion of the exhaust gas, and the inner portion and the outer portion cooperatively define a first cavity defining a first flow path for a second portion of the exhaust gas and a second cavity defining a second flow path for a third portion of the exhaust gas. The first flow path is configured to direct the second portion of the exhaust gas past the metered reductant receiving opening and into the main flow path to increase the momentum of the metered reductant into the main flow path. The second flow path is configured to direct the third portion of the exhaust gas to the dosed reductant to reduce the momentum of the dosed reductant in the main flow path.Preferred embodiments and developments of the exhaust system according to the invention according to claim 6 are the subject matter of claims 7 and 8.In some implementations, the outer portion includes a first tube having a first diameter and the inner portion includes a second tube having a second diameter less than the first diameter.In some implementations, the part includes a mount for a dosing module. In some implementations, the inner portion includes a first opening and a second opening. The first opening allows the second portion of the fluid to flow from the first flow path into the main flow path, and the second opening allows the third portion of the fluid to flow from the second flow path into the main flow path. A portion of the first opening and a portion of the second opening are positioned on opposite sides of the inner part.Claim 9 relates to a method of assembling an exhaust system with an exhaust assisted pipe assembly. The method includes providing an exhaust assisted pipe assembly having an upstream portion and a downstream portion. The exhaust-assisted pipe assembly includes an outer pipe and an inner pipe joined together at an outlet end of the inner pipe, and one or more longitudinal walls extending from the inner pipe to the outer pipe. The outer tube comprises an opening for metering reducing agent. The inner tube defines a main flow path through the exhaust-assisted tube assembly. The outer tube, the inner tube, the joined outlet end, and the one or more longitudinal walls define a first cavity for a first flow path and a second cavity for a second flow path between the outer tube and the inner tube. The inner tube includes a first opening through the inner tube to allow exhaust gas flowing along the first flow path to flow through the first cavity and into the main flow path, and a second opening through the inner tube to allow exhaust gas flowing along the second flow path to flow through the second cavity and into the main flow path. A portion of the first opening and a portion of the second opening may be positioned on opposite sides of the inner part. The method also includes connecting the upstream portion of the exhaust-assisted pipe assembly to an upstream portion of an exhaust system, and a downstream portion of the exhaust-assisted pipe assembly to a downstream portion of an exhaust system. The method further includes mounting a dosing module to a bracket of the exhaust-assisted pipe assembly.According to claim 10, the second flow path is configured to direct the third portion of the exhaust gas to the dosed reductant to reduce the momentum of the dosed reductant in the main flow path.The details of one or more implementations are specified in the accompanying figures, the claims, and the following description. Other features, aspects, and advantages of the disclosure will be apparent from the description, figures, and claims. In the drawing, the following is: FIG. 1 is a schematic block diagram of an example selective catalytic reduction system including an example reductant delivery system for an exhaust system. FIG. 2 is a side cross-sectional view of an exemplary mining reactor tube including an exhaust assisted tube assembly for dosing reductant into the mining reactor tube. FIG. 3 is a front perspective view of the exhaust-assisted pipe of the exhaust-assisted pipe assembly of FIG. 2. FIG. 4 is a rear perspective view of the exhaust-assisted pipe of the exhaust-assisted pipe assembly of FIG. 2. FIG. 5 is a front view of the exhaust-assisted tube and dosing module of the exhaust-assisted tube assembly of FIG. 2. FIG. 6A is a graphical view illustrating the exhaust assisted pipe assembly of FIG. 2 showing exhaust flow flow lines in a first operating state. FIG. 6B is a graphical view illustrating the exhaust-assisted pipe assembly of FIG. 2 showing exhaust flow flow lines in a second operating state. FIG. 6C is a graphical view illustrating the exhaust assisted pipe assembly of FIG. 2 showing exhaust flow flow lines in a third operating state. FIG. 7A is a graphical view illustrating the exhaust-assisted pipe assembly of FIG. 2, showing reductant spray distribution and particle size in the first operating state. FIG. 7B is a graphical view illustrating the exhaust-assisted pipe assembly of FIG. 2, showing reductant spray distribution and particle size in the second operating state. FIG. 7C is a graphical view illustrating the exhaust-assisted pipe assembly of FIG. 2, showing reductant spray distribution and particle size in the third operating state. FIG. 8A is a graphical view illustrating the exhaust assisted pipe assembly of FIG. 2, showing an exhaust flow velocity profile in the first operating state. FIG. 8B is a graphical view illustrating the exhaust assisted pipe assembly of FIG. 2, showing an exhaust flow velocity profile in the second operating state. FIG. 8C is a graphical view illustrating the exhaust assisted pipe assembly of FIG. 2, showing an exhaust flow velocity profile in the third operating state. FIG. 9A is a graphical view illustrating the exhaust-assisted pipe assembly of FIG. 2, showing reductant mass distribution in the first operating state. FIG. 9B is a graphical view illustrating the exhaust-assisted pipe assembly of FIG. 2, showing reductant mass distribution in the second operating state. FIG. 9C is a graphical view illustrating the exhaust-assisted pipe assembly of FIG. 2, showing reductant mass distribution in the third operating state. FIG. 10 is a graphical view of an amount of dosed reductant, an amount of vaporized reductant, and an amount of reductant forming a film on a wall of the exhaust system. FIG. 11 is a block diagram of an example manufacturing method for assembling an exhaust system with the exhaust-assisted pipe assembly.It will be appreciated that some or all of the figures are schematic representations for purposes of illustration. The figures are provided for the purpose of illustrating one or more implementations with the explicit understanding that they are not used to limit the scope or meaning of the claims.Described below in more detail are various concepts and implementations of methods, apparatus, and systems for injecting and mixing a reductant into an exhaust stream of a vehicle. The various concepts introduced above and described in more detail below may be implemented in a variety of ways, as the described concepts are not limited to a particular implementation manner. Examples of specific implementations and applications are provided primarily for illustrative purposes.I. OverviewIn exhaust systems with SCR systems, different dosing modules and / or exhaust pipe configurations may be used. For example, air-assisted or air-free dosing modules may be used. Also, in some exhaust systems, different bends and straight portions of the exhaust pipe are used in routing the exhaust system. The dosing module for an exhaust system may be positioned at different locations and / or angles to dose reductant into an exhaust system. For example, a dosing module may be positioned on an elbow of the exhaust pipe of an exhaust system to dose reductant into the exhaust system, such as substantially axially aligned with a downstream leg of the elbow. In other implementations, the dosing module may be positioned on a side of a straight portion of the exhaust pipe of an exhaust system to dose reductant into the exhaust system. In some cases, the dosing module may be angled relative to the exhaust flow at an angle that is non-parallel to the exhaust flow and / or non-perpendicular to the exhaust flow.In some implementations, to maximize the amount of vaporized reductant, dosing modules may be used at a sufficient rate to introduce the reductant into a high-speed exhaust stream. However, under lower speed conditions, such dosing modules may inject reductant at a high speed such that deposits may form on a surface opposite the dosing module. In some implementations, coatings are applied to the sidewalls to substantially avoid build-up of deposits. In some implementations, a dosing module with a lower injection speed may be used. However, at exhaust flow conditions with higher velocity conditions, the low velocity of the injected reductant may result in less vaporization and / or mixing of the reductant with the exhaust gases, resulting in poor uniformity of the reductant.To manage the varying exhaust flow speeds and conditions, a portion of the exhaust flow may be used to assist in distributing reductant into the exhaust system. For example, a portion of the exhaust flow pattern may be redirected and oriented via a nozzle of the dosing module such that the dosed reductant may enter the center of the exhaust flow without encountering a sidewall of a mining reactor tube. The exhaust flow diverted to assist the dosed reductant may thus vary depending on the exhaust flow flowing through the rest of the exhaust system, thereby providing sufficient momentum of the dosed reductant to enter the main exhaust flow. As a result, the degradation of the reducing agent in the exhaust gas stream can also be optimized by minimizing the mass transfer between the dosed reducing agent and the side walls, while maximizing the heat transfer between the dosed reducing agent and the exhaust gases. Additionally, the portion of the exhaust stream may protect and / or minimize the tip temperatures of the dosing module while simultaneously cleaning the tip of the dosing module to avoid the formation of deposits.In some implementations, a second portion of the exhaust flow may be used to slow the dosed reductant before it contacts the sidewall of a portion of the exhaust system. That is, a second portion of the exhaust gas may be diverted opposite the dosing module to provide a counter flow to the exhaust gas stream and the dosed reductant from the first portion. The second portion of the diverted exhaust flow may therefore flow slowly and / or direct the dosed reductant away from the sidewall of the exhaust system, thereby reducing the amount of reductant impinging on the sidewalls, thereby reducing the formation of deposits. In some cases, the second portion may be upstream, downstream, and / or aligned with the dosing module to control the flow of the dosed reductant into the exhaust system.Overview of the Aftertreatment SystemFIG. 1 illustrates an aftertreatment system 100 including an example reductant delivery system 110 for an exhaust system 190. The aftertreatment system 100 includes a diesel particulate filter (DPF) 102, the reductant delivery system 110, a reactor 104, and an SCR catalyst 106.The DPF 102 is configured to remove particulate matter such as soot from the exhaust gas flowing in the exhaust system 190. The DPF 102 includes an inlet where the exhaust gas is received and an outlet where the exhaust gas exits after the particulate matter is substantially filtered out of the exhaust gas and / or the particulate matter is converted to carbon dioxide.The decomposition chamber 104 is configured to convert a reductant such as urea, aqueous ammonia, or diesel exhaust fluid (DEF) into ammonia. The mining chamber 104 includes a reductant delivery system 110 having a dosing module 112 configured to dose the reductant into the mining chamber 104. In some implementations, urea, aqueous ammonia, or DEF are injected upstream of the SCR catalyst 106. The reductant droplets then pass through processes of evaporation, photolysis, and hydrolysis to form gaseous ammonia within the exhaust system 190. The decomposition chamber 104 includes an inlet in fluid communication with the DPF 102 to receive the exhaust gas containing NO x- emissions and an outlet for the exhaust gas, NO x- emissions, ammonia, and / or residual reductant to flow to the SCR catalyst 106.The decomposition chamber 104 includes the dosing module 112 mounted to the decomposition chamber 104 such that the dosing module 112 may dose a reductant such as urea, aqueous ammonia, or DEF into the exhaust gases flowing in the exhaust system 190. The dosing module 112 may each include an insulator 114 positioned between a portion of the dosing module 112 and the portion of the mining chamber 104 to which the dosing module 112 is attached. The dosing module 112 is fluidly connected to one or more reductant sources 116. In some implementations, a pump (not shown) may be used to pressurize the reductant source 116 to supply the dosing module 112.The dosing module 112 is also electrically or communicatively connected to a controller 120. The controller 120 is configured to control the dosing module 112 to dose reductant into the degradation chamber 104. The controller 120 may include a microprocessor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc., or combinations thereof. The controller 120 may include memory, which may include, but is not limited to, electronic, optical, magnetic, or any other storage or transmission device capable of supplying program instructions to a processor, ASICs, FPGAs, etc. The memory may include a memory chip, an EEPROM (electrically erasable programmable read-only memory), an EPROM (erasable programmable read-only memory), flash memory, or any other suitable memory from which the controller 120 may read instructions. The instructions may include code from any suitable programming language.The SCR catalyst 106 is configured to promote the reduction of NO x- emissions by accelerating the NO x- reduction process between the ammonia and the NO x of the exhaust gas in diatomic nitrogen, water, and / or carbon dioxide. The SCR catalyst 106 includes an inlet in fluid communication with the decomposition chamber 104 from which the exhaust gas and reductant is received, and an outlet in fluid communication with an end of the exhaust system 190.The exhaust system 190 may further include a diesel oxidation catalyst (DOC) in fluid communication with the exhaust system 190 (e.g., downstream of the SCR catalyst 106 or upstream of the DPF 102) for oxidizing hydrocarbons and carbon monoxide in the exhaust gas.Under conditions of high exhaust flow rates, the dosed reductant from the dosing module 112 may not be able to permeate through the high-speed exhaust flow, which may result in poor uniformity of the reductant.III. Exemplary Exhaust Assisted Pipe AssemblyFIG. 2 illustrates a side cross-sectional view of an example mining reactor tube 200 having an exhaust-assisted tube assembly 210 for dosing reductant into the mining reactor tube 200. FIGS. 3-4 illustrate front (FIG. 3 ) and rear (FIG. 4 ) perspective views of the exhaust-assisted pipe assembly 210. FIG. 5 illustrates a front view of the exhaust assisted pipe assembly 210. The exhaust assisted pipe assembly 210 includes an outer portion 212 and an inner portion 220. The outer portion 212 may be a cylindrical or tubular tube configured to connect to a portion of an exhaust system. For example, the outer portion 212 may include connections to be attached to a portion of the exhaust system upstream of the exhaust-assisted pipe assembly 210 and to a portion of the exhaust system piping downstream of the exhaust-assisted pipe assembly 210. In some implementations, the exhaust-assisted pipe assembly 210 may be connected to a portion of the degradation reactor pipe 200 of an exhaust system. The outer portion 212 includes an opening 214 through which reductant such as urea, aqueous ammonia, or DEF may be introduced into the decomposition reactor tube 200 from a dosing module 290. In some implementations, the dosing module 290 may be mounted to the outer portion 212 of the exhaust-assisted pipe assembly 210.The inner part 220 includes a structure to form a first flow path and a second flow path, such as an upper flow path and a lower flow path, a front flow path and a rear flow path, and / or a left flow path and a right flow path. In the present example, the inner part 220 may comprise a cylindrical or tubular tube having a smaller diameter than the cylindrical tube of the outer part 212 nested within the outer part 212. That is, the outer portion 212 may include a first tube having a first diameter and the inner portion 220 may include a second tube having a second diameter less than the first diameter. In other implementations, the inner part 220 may include a first flat plate and a second flat plate, a square tube, separate cylindrical tubes for a first flow path and a second flow path, etc. In the present example, the inner part 220 forms a first cavity 230 and a second cavity 240 between the inner part 220 and the outer part 212. In some implementations, the first cavity 230 and the second cavity 240 may be separated by one or more walls 250 (shown in FIGS. 3 and 5 ). The cylindrical tube of the inner part 220 is connected to the outer part 212 via an outlet end 222 which substantially blocks the exhaust flow from flowing out of the rear end of the first cavity 230 and the second cavity 240. Thus, the inner portion 220 and the outer portion 212 form three separate flow paths, a main flow path for a first portion of fluid from an upstream source, a first flow path for a second portion of fluid from the upstream source, and a second flow path for a third portion of fluid from the upstream source, such as exhaust gas, flowing through the exhaust-assisted pipe assembly 210. The main flow path is defined by the interior of the inner part 220. The first flow path is defined by the first cavity 230 formed by the inner portion 220 and the outer portion 212. The second flow path is defined by the second cavity 240 formed by the inner portion 220 and the outer portion 212. Thus, the exhaust flow through the exhaust-assisted pipe assembly 210 is divided into three flow paths, such that the flow profile generated by the division is the same regardless of the exhaust flow rate through the mining reactor pipe 200.The inner portion 220 of the first cavity 230 includes a first opening 232 through the inner portion 220 to allow exhaust gas flowing along the first flow path to flow through the first cavity 230 and back into the main flow path through the inner portion 220. In some implementations, the first opening 232 is a circular opening. In other implementations, the first opening 232 may have other geometric configurations, such as a rectangular slot, a tear-like shape, an oval opening, a square opening, an egg-like opening, a triangular opening, etc. The inner portion 220 of the second cavity 240 includes a second opening 242 through the inner portion 220 to allow exhaust gas flowing along the second flow path to flow through the second cavity 240 and back into the main flow path through the inner portion 220. In some implementations, the second opening 242 is a rectangular opening. In other implementations, the second aperture 242 may have other geometric configurations, such as a circular aperture, a tear-like shape, an oval aperture, a square aperture, an egg-like aperture, a triangular aperture, etc.A portion of the first opening 232 may be positioned relative to the opening 214 in the outer portion 212 such that the reductant metered by the metering module 290 flows into the main flow path. The reductant sprayed from the dosing module 290 may be introduced to avoid contact with the cooling chamber walls as it mixes with the exhaust flow to promote water evaporation and urea degradation. The exhaust flowing along the first flow path may be used to accelerate particles from the reductant spray away from the chamber walls at different exhaust speeds. That is, the exhaust flow pattern is redirected via the first flow path such that the spray plume of reductant from the dosing module 290 enters the center of the flow without encountering the wall.The first flow path is configured to direct the flow of exhaust gas past the metered reductant receiving opening and into the main flow path to increase the momentum of the metered reductant into the main flow path. The exhaust flow through the first flow path increases the radial momentum of the reductant spray such that the reductant may enter the center of the main exhaust flow path. This optimizes degradation of the reductant spray by minimizing mass transfer between the reductant spray and the walls of the degradation reactor tube 200 while maximizing heat transfer between the reductant spray and the exhaust gases. Additionally, the exhaust flow also provides a warm cleaning stream to clean the tip of the injector in the dosing module 290, which may assist in preventing small particles of reductant from circulating around the injector and forming deposits on the nozzle. The nozzle of the dosing module 290 may be protected via the exhaust flow along the first flow path and the exhaust flow may minimize peak temperatures. The flow remains abutting the tube wall, thereby avoiding deposits and producing a high uniformity index indicative of flow uniformity. Thus, the exhaust assisted pipe assembly 210 aligns the exhaust flow to assist reductant uniformity while minimizing fluid contact with the chamber walls.At low exhaust velocity conditions, it may be sufficient if the reductant spray is sprayed from the dosing module 290 into the center of the main exhaust flow path with minimal assistance from the exhaust flowing along the first flow path. Under high exhaust velocity conditions, it may not be sufficient for the reductant spray to be sprayed from the dosing module 290 into the center of the main exhaust flowpath. Thus, the high velocity of the exhaust flow flowing along the first flow path is used to increase the momentum of the spray of reductant from the dosing module 290 into the exhaust flow flowing along the main flow path. The exhaust assistance may improve the uniformity of the reductant downstream of the exhaust assisted pipe assembly 210. In some implementations, a mixing element 288 may also be positioned downstream of the exhaust-assisted pipe assembly 210 to assist in mixing the reductant with the exhaust gas.While the first flow path formed by the first cavity 230 assists the reductant spray in reaching the center of the main exhaust flow path, in some cases the reductant spray may impinge on an opposing portion of the exhaust-assisted pipe assembly 210 and / or another portion of an exhaust system, thereby potentially forming reductant puddles and / or solid deposits. For example, at low exhaust velocity conditions, the reductant spray momentum may be greater than the exhaust flow momentum and may impinge on an opposing portion of the mining reactor tube 200 to the dosing module 290. Thus, in some implementations, a second flow path of exhaust gas may be used to direct a portion of the exhaust flow to the dosed reductant to reduce the momentum of the dosed reductant and slow the reductant spray as the spray approaches the opposing wall, and / or otherwise direct the reductant spray away from the wall of the degradation reactor tube 200.The second opening 242 through the inner part 220 allows exhaust gas flowing along the second flow path to flow through the second cavity 240 and back into the main flow path through the inner part 220. The exhaust flowing along the second flow path may be used to assist in braking particles of the reductant spray approaching the chamber wall relative to the dosing module 290 at different exhaust flow rates. For example, a portion of the second opening 242 may be positioned relative to the reductant spray from the dosing module 290 such that the exhaust gas flowing along the second flow path reduces the radial momentum of the spray as the reductant spray approaches the opposite side of the mining reactor tube 200. The second opening 242 may be upstream of the first opening 232, downstream of the first opening 232, and / or aligned with the first opening 232. In some implementations, a portion of the first opening 232 and a portion of the second opening 242 are formed by the inner portion 220 on opposite sides of the inner portion 220, such as opposite one another from a tubular inner portion 220. At high exhaust velocity, the exhaust flowing along the second flow path may be sufficient to substantially prevent the reductant sprayed from the dosing module 290 from impinging the wall of the mining reactor tube 200 by reducing the radial momentum of the reductant applied by the exhaust flow through the first flow path. At low exhaust flow velocity, the exhaust flowing along the second flow path may also be slow, but sufficient to substantially prevent the reductant sprayed from the dosing module 290 from impinging on the wall of the mining reactor tube 200. In some cases, even at low exhaust velocity, the exhaust flow may not be sufficient to prevent the particles from impinging on the opposing portion of the mining reactor tube 200 and / or the exhaust-assisted tube assembly 210. The second flow path via the second cavity 240 and the exhaust gas along the main flow path and / or the first flow path allow hot exhaust gas to flow on one or both sides of the impingement area, thereby increasing convective heat transport and substantially preventing wall film formation. That is, under some low speed conditions, the exhaust gas flowing along the second flow path through the second cavity 240 may increase the temperature of an outer surface of a wall of the inner portion 220 where reductant sprayed from a dosing module may impinge, and the exhaust gas flowing along the main flow path and / or along the first flow path may increase the temperatures of an inner surface of the wall of the inner portion 220 where reductant sprayed from a dosing module may impinge. This increases convective heat transfer to the wall of the inner portion 220 where reductant sprayed from a dosing module may impinge and may substantially prevent wall film formation.In some implementations, the outlet end 222 may include one or more openings to allow the exhaust gas to flow out of the first and / or second cavities 230, 240. The one or more openings may be sized and / or positioned to adjust the flow of exhaust gas through the first flow path and / or the second flow path. In some implementations, the outlet end 222 may be positioned immediately downstream of the first opening 232 and / or the second opening 242. In some cases, the outlet end 222 may be tapered to direct the flow of exhaust gas through the first and / or second cavities 230, 240 through the first opening 232 and / or the second opening 242.In some implementations, a plurality of first openings 232 and / or second openings 242 may be formed in the interior portion 220 of the exhaust-assisted pipe assembly 210. For example, a plurality of second openings 242 may form a V-shaped or arc pattern to control the flow of exhaust gas and reductant. In some implementations, the exhaust-assisted pipe assembly 210 may be a molded component. In particular implementations, the exhaust-assisted pipe assembly 210 may be sized to be used with a wide variety of diameters of mining reactor pipe 200, including, for example, a 5 inch (127 mm) diameter mining reactor pipe 200.FIGS. 6A-6C are graphical views illustrating the exhaust assisted pipe assembly of FIG. 2 and showing exhaust flow streamlines 300 a, 300 b, 300 cin different operating states. For example, FIG. 6A shows the exhaust flow flow lines 300 ain a first operating state having a low exhaust flow flow velocity. FIG. 6B shows the exhaust flow flow lines 300 bin a second operating state having an average exhaust flow flow velocity. FIG. 6C shows the exhaust flow flow lines 300 cin a third operating state having a high exhaust flow flow velocity.FIGS. 7A-7C are graphical views illustrating the exhaust-assisted pipe assembly of FIG. 2 and showing reductant spray distribution 400 a, 400 b, 400 cand particle size in different operating states. For example, FIG. 7A shows reductant spray distribution 400 aand particle size in the first operating state having a low exhaust flow flow rate. FIG. 7B shows reductant spray distribution 400 band particle size in the second operating state having an average exhaust flow flow rate. FIG. 7C shows reductant spray distribution 400 cand particle size in the third operating state having a high exhaust flow flow rate.FIGS. 8A-8C are graphical views illustrating the exhaust assisted pipe assembly of FIG. 2 and showing an exhaust flow velocity profile 500 a, 500 b, 500 cin different operating conditions. For example, FIG. 8A shows the exhaust flow velocity profile 500 ain the first operating state having a low exhaust flow velocity. FIG. 8B shows the exhaust flow velocity profile 500 bin the second operating state having an average exhaust flow velocity. FIG. 8C shows the exhaust flow velocity profile 500 cin the third operating state, which has a high exhaust flow velocity.FIGS. 9A-9C are graphical views illustrating the exhaust assisted pipe assembly of FIG. 2 and showing reductant mass distribution 600 a, 600 b, 600 cin different operating conditions. FIG. 9A shows reductant mass distribution 600 ain the first operating state having a low exhaust flow velocity. FIG. 9B shows reductant mass distribution 600 bin the second operating state having an average exhaust flow flow velocity. FIG. 9C shows the reductant mass distribution 600 cin the third operating state having a high exhaust flow velocity.FIG. 10 is a graphical view of a mass fraction of dosed 710 reductant, a mass fraction of vaporized 720 reductant, and a mass fraction of reductant forming a film 730 on a wall of the exhaust system for the exhaust-assisted pipe assembly 210 of FIG. 2. Approximately 60.4% of the dosed reductant is broken down into ammonia while 28.9% of the dosed reductant is deposited on a surface of the exhaust system.FIG. 11 is a block diagram of an example manufacturing method 1100 for assembling an exhaust system with an exhaust assisted pipe assembly. The method 1100 may include providing an exhaust assisted pipe assembly (block 1110). The exhaust assisted pipe assembly includes an outer portion and an inner portion. The outer portion may be a cylindrical tube configured to connect to a portion of an exhaust system. For example, the outer portion may comprise fasteners to be attached to a portion of the exhaust system upstream of the exhaust assisted pipe assembly and a portion of the exhaust system piping downstream of the exhaust assisted pipe assembly. In some implementations, the exhaust-assisted pipe assembly may be connected to a portion of a decomposition reactor pipe of an exhaust system. The outer portion includes an opening through which reductant such as urea, aqueous ammonia, or DEF may be introduced into the degradation reactor tube from a dosing module.The inner portion of the exhaust-assisted pipe assembly includes a structure for forming a first flow path and a second flow path. The structure may comprise a cylindrical tube having a smaller diameter than the cylindrical tube of the outer part nested within the outer part. In other implementations, the inner portion may include a first flat plate and a second flat plate, a square tube, separate cylindrical tubes for a first flow path and a second flow path, etc. The inner part forms a first cavity and a second cavity between the inner part and the outer part. In some implementations, the first cavity and the second cavity may be separated by one or more walls. The cylindrical tube of the inner part is connected to the outer part via an outlet end that substantially blocks the exhaust flow from flowing out of the rear end of the first cavity and the second cavity. Therefore, the inner part and the outer part form three separate flow paths, a first flow path, a second flow path, and a main flow path for exhaust gas flowing through the exhaust-assisted pipe assembly.The exhaust flow through the exhaust-assisted pipe assembly is divided into three flow paths, such that the flow profile generated by the division is the same regardless of the exhaust flow rate through the mining reactor pipe. The inner portion of the first cavity includes a first opening through the inner portion to allow exhaust gas flowing along the first flow path to flow through the first cavity and back into the main flow path through the inner portion. In some implementations, the first opening is a circular opening. In other implementations, the first opening may have other geometric configurations, such as a rectangular slot, a tear-like shape, an oval opening, a square opening, an egg-like opening, a triangular opening, etc. The interior portion of the second cavity includes a second opening through the interior portion to allow exhaust gas flowing along the second flow path to flow through the second cavity and back into the main flow path through the interior portion. In some implementations, the second opening is a rectangular opening. In other implementations, the second opening may have other geometric configurations, such as a circular opening, a tear-like shape, an oval opening, a square opening, an egg-like opening, a triangular opening, etc.The method 1100 further includes connecting the provided exhaust assisted pipe assembly to an upstream portion and a downstream portion of an exhaust system (block 1120). In some implementations, an upstream portion of the exhaust-assisted pipe assembly may be fluidly connected to the upstream portion of the exhaust system, such as via inserting a portion of the exhaust-assisted pipe assembly into the upstream portion of the exhaust system and / or inserting a portion of the upstream portion of the exhaust system into a portion of the exhaust-assisted pipe assembly. In some implementations, the upstream portion of the exhaust-assisted pipe assembly may be welded to the upstream portion of the exhaust system. In some implementations, the upstream portion of the exhaust-assisted pipe assembly may be screwed to the upstream portion of the exhaust system. In further implementations, the upstream portion of the exhaust system may be press fit to the upstream portion of the exhaust assisted pipe assembly.The downstream portion of the exhaust-assisted pipe assembly may be fluidly connected to the downstream portion of the exhaust system, such as by inserting a portion of the exhaust-assisted pipe assembly into the downstream portion of the exhaust system and / or inserting a portion of the downstream portion of the exhaust system into a portion of the exhaust-assisted pipe assembly. In some implementations, the downstream portion of the exhaust-assisted pipe assembly may be welded to the downstream portion of the exhaust system. In other implementations, the downstream portion of the exhaust-assisted pipe assembly may be threaded to the downstream portion of the exhaust system. In further implementations, the downstream portion of the exhaust system may be press fit onto the downstream portion of the exhaust assisted pipe assembly.The method 1100 may further include mounting a dosing module to the exhaust assisted pipe assembly (block 1130). For example, the dosing module may be threaded, clipped, welded, and / or otherwise connected to a bracket formed on the exhaust-assisted pipe assembly such that the dosing module may dose reductant into the exhaust-assisted pipe assembly.The term "controller" includes any type of device, device, and machine for processing data, including, for example, via a programmable processor, a computer, an SOC, or more, a portion of a programmed processor, or combinations of the foregoing. The device may comprise special purpose logic circuitry, e.g., a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). The apparatus may also include, in addition to hardware, code that creates an execution environment for the subject computer program, e.g., code that includes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more thereof. The apparatus and execution environment may implement different computational model infrastructures such as distributed computing and grid computing infrastructures.Although this specification contains many specific implementation details, these should not be construed as limitations on the scope of what is claimed, but rather as descriptions of features specific to particular implementations. Certain features described in this specification in the context of separate implementations may also be implemented in combination with a single implementation. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features are described above as acting in certain combinations or even initially claimed as such, one or more features from a claimed combination may in some cases be taken out of the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.As used herein, the words "substantially" and similar words are intended to have a broad meaning consistent with common and accepted use by persons of ordinary skill in the art to which the subject of this disclosure pertains. It should be understood by those skilled in the art that these terms are intended to allow a description of certain features described and claimed without limiting the scope of these features to the exact ranges of numbers given unless otherwise indicated. Accordingly, the terms should be construed to mean that minor or non-limiting modifications or alterations of the described and claimed subject matter as set forth in the appended claims are deemed to be within the scope of the invention. Moreover, it should be noted that constraints in the claims should not be interpreted to mean "means plus function" constraints under the U.S. patent law in the event that the word "means" is not used therein.The words "connected / coupled", "connected" and the like in this document mean the direct or indirect connection of two components to one another. Such a connection may be stationary (e.g., permanent) or mobile (e.g., removable or releasable). Such connection may be achieved with the two components or the two components and additional intermediate components integrally formed as a single unitary body with each other or with the two components or the two components and additional intermediate components secured together.The terms "fluidly coupled," "in fluid communication with each other," and the like, as used herein, mean that two components or objects have formed a path between the two components or objects through which a fluid, such as water, air, gaseous reductant, gaseous ammonia, etc., can flow, either with or without intervening components or objects. Examples of fluid connections or configurations to enable fluid communication may be tubes, channels, or other suitable components that enable the flow of a fluid from one component (or object) to the other.It is important to note that the construction and arrangement of the system as shown in the various exemplary implementations are illustrative only and are not limiting in nature. It is intended to protect all changes and modifications that may come within the spirit and / or scope of the described implementations. It should be understood that some features may be unnecessary and that implementations lacking various features may be considered to conform to the scope of the application, the scope being defined by the following claims. When words such as "a", "at least one", or "at least a portion" are used in reading the claims, this is not intended to limit the claim to only one element unless the claim specifically indicates the opposite. When the term "at least a portion" and / or "a portion" is used, the element may include a portion and / or the entire element unless specifically stated to the contrary.

Claims

An exhaust-assisted pipe assembly (210) comprising an outer portion (212) having an opening (214) for receiving metered reductant from a metering module (290), and an inner portion (220) disposed within the outer portion (212), the inner portion defining a main flow path for receiving a first portion of fluid from an upstream source, the inner portion and the outer portion cooperatively defining a first cavity (230) for a first flow path between the inner portion and the outer portion and a second cavity (240) for a second flow path between the inner portion and the outer portion, the first cavity and the second cavity being separated by a longitudinally extending wall (250) connecting the outer portion to the inner portion, the first flow path of the first cavity (230) being configured to:, A method of receiving dosed reductant from the dosing module (290) through the opening (214) of the outer part (212) and directing a second portion of the fluid from the upstream source past the dosed reductant receiving opening (214) and into the first main flow path to increase the momentum of the dosed reductant into the main flow path, and wherein the second flow path of the second cavity (240) is configured to direct a third portion of the fluid from the upstream source to the dosed reductant to decrease the momentum of the dosed reductant in the main flow path.The exhaust assisted pipe assembly (210) of claim 1, characterized in that the fluid is an exhaust gas and / or that the inner part (220) is a tubular member and / or that the outer part (212) and the inner part (220) comprise straight tubular parts.The exhaust-assisted pipe assembly (210) of any preceding claim, characterized in that the inner portion (220) includes a first opening (232) and a second opening (242), the first opening (232) allowing the second portion of the fluid to flow from the first flow path into the main flow path, and the second opening (242) allowing the third portion of the fluid to flow from the second flow path into the main flow path, preferably wherein at least a portion of the first opening (232) is positioned relative to the opening (214) of the outer portion (212) such that metered reductant from the metering module (290) flows through the first opening into the main flow path, and / or wherein the second opening (242) is upstream relative to the first opening (232), or wherein the second opening (242) is downstream relative to the first opening (232), and / or wherein the second opening (242) is oriented opposite the first opening (232).The exhaust-assisted pipe assembly (210) of any preceding claim, characterized in that an outlet end (222) of the inner part (220) is connected to the outer part (212), wherein, preferably, the outlet end (222) of the inner part connected to the outer part blocks the second part of the fluid flowing along the first flow path so as not to flow out of an outlet end of the first cavity (230), wherein, more preferably, the outlet end (22) of the inner part connected to the outer part blocks the third part of the fluid flowing along the second flow path so as not to flow out of an outlet end of the second cavity (240).The exhaust-assisted pipe assembly (210) of any preceding claim, characterized in that the third portion of the fluid flowing along the second flow path increases a temperature of a surface of the inner portion (212).An exhaust system (190) comprising a first exhaust system portion receiving exhaust gas and a second exhaust system portion, an exhaust assisted pipe assembly (210) connected at an upstream end to the first exhaust system portion for receiving exhaust gas therefrom and connected at a downstream end to the second exhaust system portion, the exhaust assisted pipe assembly (210) comprising an outer portion (212) having an opening (214) for receiving a dosed reductant from a dosing module (290), and an inner portion (220) disposed within the outer portion, the inner portion (220) defining a main flow path through the inner portion for receiving a first portion of the exhaust gas, the main flow path being configured to direct a first exhaust portion along a surface of the inner portion opposite the dosing module (290), to increase a temperature of the inner part, the inner part and the outer part cooperatively define a first cavity (230) defining a first flow path for a second exhaust part and a second cavity (240) defining a second flow path for a third exhaust part, the first cavity and the second cavity are separated by a longitudinally extending wall (250) connecting the outer part to the inner part, the first flow path of the first cavity (230) is configured to receive dosed reductant from the dosing module through the opening (214) of the outer part, and to direct the second exhaust part past the opening (214) for receiving dosed reductant and into the main flow path to increase momentum of the dosed reductant into the main flow path, and the second flow path of the second cavity (240) is configured to direct the third exhaust portion to the dosed reductant to reduce the momentum of the dosed reductant in the main flow path and is configured to direct the third exhaust portion along the surface of the inner portion (220) to increase the temperature of the inner portion.The exhaust system (190) according to claim 6, characterized in that the outer part (212) comprises a first pipe having a first diameter, and that the inner part (220) comprises a second pipe having a second diameter smaller than the first diameter, and / or that the outer part comprises a holder for a dosing module.The exhaust system (190) of claim 6 or 7, characterized in that the inner portion (220) comprises a first opening (232) and a second opening (242), the first opening allowing the second portion of the fluid to flow from the first flow path into the main flow path, the second opening allowing the third portion of the fluid to flow from the second flow path into the main flow path, a portion of the first opening and a portion of the second opening being positioned on opposite sides of the inner portion.A method (1100) of assembling an exhaust system with an exhaust assisted pipe assembly, comprising: providing an exhaust assisted pipe assembly (210) having an upstream portion and a downstream portion, the exhaust assisted pipe assembly comprising an outer pipe (212) and an inner pipe (220) joined together at an outlet end (222) of the inner pipe, and one or more longitudinal walls (250) extending from the inner pipe to the outer pipe, the outer pipe comprising an opening (214) for metering reductant and the inner pipe defining a main flow path through the exhaust assisted pipe assembly, the outer pipe, the inner pipe, the connected outlet end and the one or more longitudinal walls define a first cavity (230) for a first flow path and a second cavity (240) for a second flow path between the outer tube and the inner tube, the inner tube comprising a first opening (232) through the inner tube to allow exhaust gas flowing along the first flow path and a reductant metered through the opening (214) of the outer part to flow through the first cavity (230) and into the main flow path, the inner tube comprising a second opening (242) through the inner tube to allow exhaust gas flowing along the second flow path to flow through the second cavity (240) and into the main flow path, a portion of the first opening and a portion of the second opening being positioned on opposite sides of the inner part, connecting the upstream portion of the exhaust assisted pipe assembly (210) to an upstream portion of an exhaust system, and a downstream portion of the exhaust assisted pipe assembly (210) to a downstream portion of an exhaust system, and mounting a dosing module (290) to a mount of the exhaust assisted pipe assembly.The method of claim 9, characterized in that the second flow path is configured to direct the third portion of the exhaust gas to the dosed reductant to reduce momentum of the dosed reductant in the main flow path.

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