Patent Publication Number: US-11022077-B2

Title: EGR cooler with Inconel diffuser

Description:
TECHNICAL FIELD 
     This disclosure relates to an exhaust gas recirculation (EGR) cooler, and in particular, to an exhaust gas recirculation (EGR) cooler having an Inconel diffuser. 
     BACKGROUND 
     In internal combustion engines, such as gasoline and diesel fueled engines, exhaust gas recirculation (EGR) is often used to reduce nitrogen oxide (NOx) emissions. EGR works by recirculating a portion of the engine&#39;s exhaust gas back to the engine cylinders. EGR systems often include a heat exchanger, commonly referred to as an EGR cooler, to lower the temperature of the exhaust gas being recirculated to the intake of the internal combustion engine. 
     Lowering the temperature of the recirculated exhaust gas results in lower combustion temperatures, which is a key variable for reducing of NOx formation. EGR coolers are primarily stainless steel, since in the environment where the EGR cooler is located is corrosive and other metals would rust, and rust flakes can result in major damage to the engine. EGR coolers, however, are also subject to significant thermal loading and cycling, which results in high thermal stresses on the EGR coolers and the joints attaching the EGR cooler within the EGR system. Thus, EGR coolers and the joints must resist corrosion and withstand the high thermal loads experienced during operation. 
     For example, U.S. Patent Publication 2001/0047861, entitled “Brazing Method, Brazement, Method of Production of Corrosion-Resistant Heat Exchanger, and Corrosion-Resistant Heat Exchanger,” discloses a method of producing a corrosion-resistant heat exchanger made of stainless steel. The method includes plating chrome on a first stainless steel plate to form a chrome-based brazing filler metal layer. Then, plating nickel-phosphorus on the chrome-based brazing filler metal layer to form a nickel-based brazing filler metal layer on the chrome-based brazing filler metal layer. Then heating to a temperature of at least the melting point of the nickel-based brazing filler metal layer to braze the first stainless steel plate to a second stainless steel plate with the chrome-based brazing filler metal layer and the nickel-based brazing filler metal layer interposed between the two plates. Due to this, a high corrosion resistance brazing filler metal containing an Ni—Cr28-P8-etc. alloy composition is obtained between the first and second stainless steel plates. 
     SUMMARY 
     In accordance with the present disclosure there is provided a EGR cooler having a stainless steel housing and an Inconel diffuser. 
     In accordance with one aspect of the present disclosure, an EGR cooler includes an elongated, stainless steel cooler housing with a first end having a stainless steel end plate and a second end opposite the first end, and an Inconel diffuser having an inlet end defining a gas inlet and an outlet end welded to the stainless steel end plate. The stainless steel end plate having a first thickness and the outlet end of the Inconel diffuser including a sidewall having a second thickness that is 50% or less of the first thickness. 
     In accordance with another aspect of the present disclosure, an engine system, includes an internal combustion engine, having an intake manifold for directing intake air into one or more engine cylinders and an exhaust manifold for routing exhaust from the one or more engine cylinders and an exhaust system configured to receive exhaust from the exhaust manifold. The exhaust system includes an EGR conduit arranged to direct a portion of the exhaust received from the exhaust manifold into the intake manifold and an EGR cooler arranged in the EGR conduit for cooling the portion of the exhaust directed into the intake manifold. The EGR cooler includes an elongated, stainless steel cooler housing with a first end having a stainless steel end plate and a second end opposite the first end, and an Inconel diffuser having an inlet end defining a gas inlet and an outlet end welded to the stainless steel end plate. The stainless steel end plate having a first thickness and the outlet end of the Inconel diffuser including a sidewall having a second thickness that is 50% or less of the first thickness. 
     In accordance with another aspect of the present disclosure, a method of cooling an exhaust stream being routing via an exhaust conduit from an exhaust manifold on an engine to an intake manifold on the engine, includes directing coolant through a housing of a stainless steel heat exchanger, directing the exhaust stream through an Inconel diffuser welded to a stainless steel end plate at a gas inlet end of the housing, and directing the exhaust stream through a plurality of tubes extending through the housing from the gas inlet to a gas outlet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages will be evident from the following illustrative embodiment which will now be described, purely by way of example and without limitation to the scope of the claims, and with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic illustration of an exemplary engine system having an exhaust gas recirculation (EGR) valve; 
         FIG. 2  is a side view of an exemplary embodiment of an EGR cooler; and 
         FIG. 3  is a partial sectional exploded view of the header and diffuser of the EGR cooler of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     While the present disclosure describes certain embodiments of an EGR cooler having an Inconel diffuser, the present disclosure is to be considered exemplary and is not intended to be limited to the disclosed embodiments. Also, certain elements or features of embodiments disclosed herein are not limited to a particular embodiment, but instead apply to all embodiments of the present disclosure. 
     As used in this application, “Inconel,” which is a trademark of Special Metals Corporation, refers to the known family of austenitic nickel-chromium-based superalloys that use that tradename. As used in this application, “Inconel 625” refers to an austenitic nickel-chromium-based superalloy having the nominal composition ranges shown in Table 1, below: 
                                                                             TABLE 1                       Cr   Mo   Co   Nb + Ta   Al   Ti   C   Fe   Mn   Si   P   S   Ni                                                                                            Min, %   20   8   —   3.15   —   —   —   —   —   —   —   —   58.0       Max, %   23   10   1   4.15   0.4   0.4   0.1   5   0.5   0.5   0.015   0.015   Balance                    
Additional common trade names for the superalloy Inconel 625, include: Chronin 625, Altemp 625, Haynes 625, Nickelvac 625, and Nicrofer 6020. All of which are considered the same material for purposes of this specification.
 
     The terminology as set forth herein is for description of the embodiments only and should not be construed as limiting the disclosure as a whole. All references to singular characteristics or limitations of the present disclosure shall include the corresponding plural characteristic or limitation, and vice versa, unless otherwise specified or clearly implied to the contrary by the context in which the reference is made. Unless otherwise specified, “a,” “an,” “the,” and “at least one” are used interchangeably. Furthermore, as used in the description and the appended claims, the singular forms “a,” “an,” and “the” are inclusive of their plural forms, unless the context clearly indicates otherwise. 
     To the extent that the term “includes” or “including” is used in the description or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use. Furthermore, when the phrase “one or more of A and B” is employed it is intended to mean “only A, only B, or both A and B.” 
     The EGR cooler of the present disclosure can comprise, consist of, or consist essentially of the essential elements of the disclosure as described herein, as well as any additional or optional element or feature described herein or which is otherwise useful in welding applications. 
     Unless otherwise indicated, all numbers expressing parameters, such as amperage, voltage, rate, or other parameters as used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless otherwise indicated, the numerical properties set forth in the specification and claims are approximations that may vary depending on the suitable properties sought to be obtained in embodiments of the present invention. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the general inventive concepts are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical values, however, inherently contain certain errors necessarily resulting from error found in their respective measurements. In general, the term “about” modifies a numerical value above and below the stated value by 10%. 
     All ranges and parameters, including but not limited to dimensions, percentages and ratios, disclosed herein are understood to encompass any and all sub-ranges assumed and subsumed therein, and every number between the endpoints. For example, a stated range of “1 to 10” should be considered to include any and all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less (e.g., 1 to 6.1, or 2.3 to 9.4), and to each integer (1, 2, 3, 4, 5, 6, 7, 8, 9, and 10) contained within the range. 
     Referring to the drawings,  FIG. 1  is a schematic illustration of an exemplary engine system  100  having an exhaust gas recirculation (EGR) control valve  102  and an EGR cooler  128 . The engine system  100  includes an internal combustion engine  104 , such as a diesel engine. The engine  104  may provide power to various types of applications and/or to machines. For example, the engine  104  may power a machine such as an off-highway truck, a railway locomotive, an earth-moving machine, such as a wheel loader, excavator, dump truck, backhoe, motor grader, material handler, or the like. The term “machine” can also refer to stationary equipment like a generator that is driven by an internal combustion engine to generate electricity. 
     The engine  104  includes one or more cylinders  105  implemented therein. In the illustrated embodiment, the engine  104  includes four cylinders  105 . In other embodiments, however, the engine  104  may include more or less than four cylinders  105 . The engine  104  may be of an in-line type, a V-type, a rotary type, or other types known in the art. Each of the cylinders  105  may be configured to slidably receive a piston (not shown) therein. 
     Each of the cylinders  105  includes one or more intake ports  106 , each having an intake valve (not shown) and one or more exhaust ports  108 , each having an exhaust valve (not shown). The intake valves and the exhaust valves are configured to regulate fluid communication into and out of the cylinders  105  via the one or more intake ports  106  and the one or more exhaust ports  108 , respectively. The engine  104  includes an intake manifold  110  in fluid communication with an intake line  112  and an exhaust manifold  114  in fluid communication with an exhaust line  116 . Intake air enters the one or more intake ports  106  from the intake line  112  via the intake manifold  110  and exhaust enters the exhaust line  116  from the one or more exhaust ports  108  via the exhaust manifold  114 . 
     The engine system  100  may also include one or more exhaust aftertreatment devices  118 , disposed in the exhaust line  116 , for trapping exhaust constituents, converting an exhaust constituent from one composition to another composition, or both. The one or more exhaust aftertreatment devices may include a particulate filter, a nitrogen oxides (NOx) conversion module, an oxidation catalyst, combinations thereof, or any other exhaust aftertreatment device known in the art. 
     The engine system  100  includes an exhaust gas recirculation (EGR) system  120  configured to recirculate a regulated amount of the exhaust received from the cylinders  105  to the intake manifold  110 . The EGR system  120  may include an EGR conduit  122  in fluid communication with the exhaust manifold  114  and in fluid communication with the intake manifold  110 . 
     The EGR system  120  includes an EGR control valve  102  disposed in the EGR conduit  122  and configured to meter the amount of the exhaust that is recirculated to the intake manifold  110  via the EGR conduit  122 . The EGR control valve  102  may selectively effect, throttle, or block a flow of exhaust gas from the exhaust manifold  114  to the intake manifold  110  via the EGR conduit  122 . For example, a position of the EGR control valve  102 , such as a valve angle, may be regulated to control the amount of exhaust being passed via the EGR conduit  122 . The engine system  100  may include an EGR actuator  126  operatively coupled to the EGR control valve  102 . The EGR actuator  126  may be configured to move the position of the EGR control valve  102  thereby controlling the amount of EGR. The EGR actuator  126  may be integral with the EGR control valve  102  or a separate component that is operatively coupled to the EGR control valve  102 . 
     The EGR cooler  128  of the engine system  100  is disposed in the EGR conduit  122 . The EGR cooler  128  is provided to reduce a temperature of the exhaust gas passing through the EGR conduit  122 . The EGR cooler  128  may be positioned upstream or downstream of the EGR control valve  102 . In some embodiments, the EGR system  120  may optionally include a bypass (not shown) around the EGR cooler  128 . It may further be contemplated to provide additional components (not shown), such as one or more turbochargers, inter-coolers, aftercoolers, filters and the like, in the engine system  100 . These components of the engine  104  are well known in the art and therefore a detailed description is not included herein. 
     The engine system  100  also includes a controller  150  configured to regulate the amount of EGR by controlling the EGR control valve  102 . The controller  150  may be configured in a variety of ways. The controller  150  may embody a single microprocessor or multiple microprocessors configured for receiving signals from the various components of the engine system  100 . It should be appreciated that the controller  150  may embody a machine microprocessor capable of controlling numerous machine functions. A person of ordinary skill in the art will appreciate that the controller  150  may additionally include other components and may also perform other functions not described herein. The controller  150  may also be configured to receive inputs from an operator via a user interface (not shown). In one exemplary embodiment, the controller  150  is an engine control module (ECM) of the engine  104 . 
       FIGS. 2-3  illustrate an exemplary EGR cooler  300 . The EGR cooler  300  is illustrated as a shell and tube heat exchanger, but other types of heat exchangers, such as a plate-type heat exchanger, may be used. The EGR cooler  300  includes an elongated, hollow, stainless steel housing  302  having a cylindrical outer side surface  304 , a first end  306 , and a second end  308  opposite the first end  306 . In the exemplary embodiment, the housing  302  is made of stainless steel 316, but in other embodiments, other stainless steel alloys may be used to make the stainless steel housing  302 . 
     The EGR cooler  300  includes a coolant inlet port  310  extending through the cylindrical outer side surface  304  to allow coolant to flow into the hollow interior of the housing  302  and a coolant outlet port  312  extending through the cylindrical outer side surface  304  to allow coolant to flow out of the hollow interior of the housing  302 . 
     The first end  306  includes a first circular end plate  320  and the second end  308  includes a second circular end plate  322  substantially similar to the first circular end plate  320 . The first and second end plates  320 ,  322  are made of stainless steel, such as for example, the same stainless steel alloy that is used for the housing  302 . As shown in  FIG. 3 , the first end plate  320  has a first side face  323 , a second side face  324  opposite and parallel to the first side face  323 , and an end face  325  extending perpendicularly between the first side face  323  and the second side face  324 . The first end plate  320  has a first thickness T 1 . In one exemplary embodiment, the first thickness T 1  is in the range of 3 mm to 5 mm. In the exemplary embodiment, the second end plate  322  has a thickness (not shown) that is the same as the first thickness T 1  of the first end plate  320 . 
     Each of the first end plate  320  and the second end plate  322  have a plurality of holes  326  extending in the thickness direction. Each of the plurality of holes  326  in the first end plate  320  align with a corresponding one of the plurality of holes  326  in the second end plate  322  to form a pair of aligned holes  326 . Each of the pair of aligned holes  326  have a stainless steel tube  328  associated therewith such that the EGR cooler includes a plurality of stainless steel tubes  328 . In particular, each stainless steel tube  328  is mounted on one end into one of the holes  326  in the first end plate  320  and is mounted on the other end to the aligned one of holes  326  in the second end plate  322 , such that each of the stainless steel tubes  328  extends through the elongated, hollow housing  302 . The EGR cooler  300  may also include a plurality of flow baffles  329  within the hollow interior of the housing  302  to create a tortious path for the coolant flowing through the housing  302  from the coolant inlet port  310  to the coolant outlet port  312 . 
     The EGR cooler  300  includes an Inconel diffuser  330  welded onto the first end plate  320  by the disclosed method. The EGR cooler  300  includes a collector  332  welded onto the second end plate  322 . In the illustrated embodiment, the collector  332  is made of stainless steel, rather than Inconel, but otherwise is substantially the same as the Inconel diffuser  330 . Thus, the description of the Inconel diffuser  330  applies equally to the collector  332 . In other embodiments, however, the collector  332  may differ from the Inconel diffuser  330  or may be made from Inconel as well. 
     The Inconel diffuser  330  defines a gas inlet  336  to the EGR cooler  300  and the collector  332  defines a gas outlet  338  from the EGR cooler  300 . The type of Inconel alloy and the type of stainless steel alloy used for the Inconel diffuser  330  and the stainless steel first end plate  320  may vary in different embodiments. In the illustrated embodiment, the Inconel first diffuser  330  is made from Inconel 625 alloy and the stainless steel first end plate  320 , the stainless steel housing  302  of the EGR cooler  300 , and the stainless steel collector  332  are made from stainless steel alloy 316. 
     In the illustrated embodiment, the Inconel diffuser  330  is made from Inconel 625 alloy. The Inconel diffuser  330  includes an inlet end  340  defining the gas inlet  336  and having an inlet diameter D 1 , and an outlet end  342 , opposite the inlet end  340 , defining a circular outlet having an outlet diameter D 2 . In the illustrated embodiment, the first end plate  320  has a diameter equal to the outlet diameter D 2 . In other embodiments, however, the diameter of the first end plate  320  may differ from the outlet diameter D 2 . 
     The Inconel diffuser  330  includes a thin-walled, outward flaring body  344  having a sidewall  345  with a wall thickness T 2  adjacent the outlet end  342 . In the illustrated embodiment, the outlet diameter D 2  is greater than the inlet diameter D 1 . For example, the inlet diameter D 1  may be in the range of 25% to 50% of the outlet diameter D 2 , such as for example 30% to 40% of the outlet diameter D 2 . 
     In the illustrated embodiment, the outlet end  342  of the Inconel diffuser  330  has an end face  349  that abuts, or is adjacent to, an outer peripheral surface  350  of the stainless steel first end plate  320  to form a weldable joint. The outer peripheral surface  350  may be the end face  325  or, as shown in the embodiment of  FIG. 3 , an outer portion of the first side face  323 . 
     In the illustrated embodiment, the outlet end  342  of the Inconel diffuser  330  has an outer surface  354  that is coplanar, or nearly coplanar, with the end face  325  of the stainless steel first end plate  320 . The Inconel diffuser  330  and the stainless steel first end plate  320  are welded in the position such that a weld bead  352  is formed over the interface between the outlet end  342  of the Inconel diffuser  330  and the outer peripheral surface  350  of the stainless steel first end plate  320 . The weld bead  352  will extend around the entire circumference of the interface between the outlet end  342  of the Inconel first diffuser  330  and the stainless steel first end plate  320  to form a welded joint  360 . 
     The welded joint  360  may be characterized as a butt joint. In will be understood, however, that in other embodiments, the Inconel diffuser  330  and the stainless steel first end plate  320  may be configured and arranged such that the welded joint is any suitable type of welded joint, such as for example, a corner joint, an edge joint, a lap joint, a tee joint, or other type of weld joint. Further, in the illustrated embodiment, the outlet end  342  of the Inconel diffuser  330  and the outer peripheral surface  350  of the stainless steel first end plate  320  are flat and parallel to each other at the weldable joint to form a single square groove. In other embodiments, however, one or more of the outlet end  342  of the Inconel diffuser  330  and the outer peripheral surface  350  of the stainless steel first end plate  320  may be configured other than flat and parallel to the other. For example, the weld joint may be a single bevel groove, double bevel groove, single-J groove, double-J groove, single-U groove, double-U groove, single-V groove, double-V groove, flanged groove, flare groove (such as a flare bevel or flare-V groove), or any suitable groove configuration. 
     The Inconel diffuser wall thickness T 2  and the stainless steel first end plate thickness T 1  may vary in different embodiments. In the illustrated embodiment, the Inconel diffuser wall thickness T 2  is less than the stainless steel first end plate thickness T 1 . For example, in some embodiments, the Inconel diffuser wall thickness T 2  is 50% or less than the stainless steel first end plate thickness T 1 , is 40% or less than the stainless steel first end plate thickness T 1 , is 35% or less than the stainless steel first end plate thickness T 1 , or is 30% or less than the stainless steel first end plate thickness T 1 . In one exemplary embodiment, the stainless steel first end plate thickness T 1  is in the range of 3 mm to 5 mm. In another exemplary embodiment, the stainless steel first end plate thickness T 1  is in the range of 3 mm to 5 mm and the Inconel diffuser wall thickness T 2  is in the range of 30% to 40% of the stainless steel first end plate thickness T 1 , such as for example in the range of 1.0 mm to 1.5 mm. 
     During manufacturing of the EGR cooler  300 , the outlet end  342  of Inconel diffuser  330  is welded to the stainless steel first end plate  320  of the housing  302  by a welding system. The welding system may be any suitable welding system that is capable of welding the disclosed Inconel diffuser  330  to the disclosed stainless steel first end plate  320 . For example, a robot-based, gas metal arc welding (GMAW) system programmed with specific welding parameters may be used to join the Inconel diffuser  330  to the stainless steel first end plate  320 . GMAW is an arc welding process in which a continuous solid weld wire electrode is fed through a welding torch/gun and into a weld pool formed between the components being welded, joining the two base materials together. It will be understood that the robot-based GMAW system may have a variety of configurations. 
     While suitable values for various welding parameters for welding stainless steel to stainless steel are well known and included in the software for many robotic welding systems, welding parameters for welding a thin-walled Inconel component to a thicker stainless steel component, such as the disclosed Inconel first diffuser  330  to the disclosed stainless steel first end plate  320 , using a robotic GMAW system, are not conventionally known. In wire feed welding, the amount of wire protruding from a distal end of the welding torch is important, and the wire feed rate must be matched with the amperage and voltage being used and controlled to maintain proper protrusion of the weld wire from a distal end of the welding torch to generate a quality weld. Inconel has a greater resistivity to electrical current than stainless steel. Thus, for a given thickness of a component, the set-points used for key welding parameters for welding stainless steel to stainless steel, such as amperage, voltage, and wire feed rate, are not suitable for welding Inconel to stainless steel. 
     For example, in an attempt to gas metal arc weld, the Inconel diffuser  330  to the stainless steel end plate  320  using conventional amperage, voltage, and wire feed settings (135 amps, 22 volts, 0.6 m/min feed rate) for welding similar stainless steel components, the welding torch essentially functioned as a plasma cutter and cut through the plates. 
     One of skill in the art, when faced with the above scenario, would tend to lower the amperage in order to, essentially, reduce the heat being delivered by the torch to the weld joint. Counterintuitive to this approach, it was found that suitable output settings from a constant voltage welding power supply to weld the Inconel diffuser  330  to the stainless steel first end plate  320  included an amperage over 225 amps, a voltage below 20 volts, and a weld wire feed rate of about 0.6 m/min when using an Inconel 625 alloy weld wire having a diameter in the range of 0.030 inches (0.762 mm) to 0.045 inches (1.14 mm). 
     INDUSTRIAL APPLICABILITY 
     The novel EGR cooler  300  may be used in a variety of applications. For example, the EGR cooler  300  may be part of an engine system used to provide power to various types of applications and/or to machines, such as for example, an off-highway truck, a railway locomotive, a marine vessel, or an earth-moving machine. The term “machine” can also refer to stationary equipment like a generator that is driven by an internal combustion engine to generate electricity (i.e., gen-sets) or a pumping station having one or more pumps driven by an internal combustion engine. 
     EGR coolers operate in a corrosive environment. Conventional EGR coolers are primarily made of stainless steels due to the corrosion resistance of the material. EGR coolers can also be exposed to significant thermal loading and cycling since there is a high temperature difference between the exhaust gas being cooled and the coolant. The EGR cooler inlet diffuser and weld between the inlet diffuser and the EGR cooler end plate experience high cyclic thermal stress and pressure stress under various operating conditions, which can result in thermal fatigue failure, such as for example, cracking at the welds. 
     The novel EGR cooler  300  utilizes a thin-walled Inconel 625 stamped inlet diffuser welded to a stainless steel 316 end plate on the EGR cooler housing. The Inconel diffuser provides both oxidation/corrosion resistance as well as improved thermal performance by retaining its strength over a wide temperature range. Thus, the novel EGR cooler is less susceptible to thermal fatigue failure under high cyclic thermal stress and pressure stress operating conditions. 
     While the novel heat exchanger is described and illustrated as an EGR cooler, it may be used in other applications were cooling a fluid stream is desired. Unless otherwise indicated herein, all sub-embodiments and optional embodiments are respective sub-embodiments and optional embodiments to all embodiments described herein. While the present disclosure has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the present disclosure, in its broader aspects, is not limited to the specific details, the representative compositions or formulations, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicant&#39;s general disclosure herein. 
     LIST OF ELEMENTS 
     
       
         
           
               
               
             
               
                   
               
               
                 Element 
                 Element 
               
               
                 Number 
                 Name 
               
               
                   
               
             
            
               
                 100 
                 engine system 
               
               
                 102 
                 control valve 
               
               
                 104 
                 internal combustion engine 
               
               
                 105 
                 cylinders 
               
               
                 106 
                 intake ports 
               
               
                 108 
                 exhaust ports 
               
               
                 110 
                 intake manifold 
               
               
                 112 
                 intake line 
               
               
                 114 
                 exhaust manifold 
               
               
                 116 
                 exhaust line 
               
               
                 118 
                 exhaust aftertreatment devices 
               
               
                 120 
                 system 
               
               
                 122 
                 EGR conduit 
               
               
                 126 
                 EGR actuator 
               
               
                 128 
                 EGR cooler 
               
               
                 150 
                 controller 
               
               
                 300 
                 EGR cooler 
               
               
                 302 
                 housing 
               
               
                 304 
                 outer side surface 
               
               
                 306 
                 first end 
               
               
                 308 
                 second end 
               
               
                 310 
                 coolant inlet port 
               
               
                 312 
                 coolant outlet port 
               
               
                 320 
                 first end plate 
               
               
                 322 
                 second end plate 
               
               
                 323 
                 first side face 
               
               
                 324 
                 second side face 
               
               
                 325 
                 end face 
               
               
                 326 
                 holes 
               
               
                 328 
                 stainless steel tube 
               
               
                 329 
                 flow baffles 
               
               
                 330 
                 Inconel diffuser 
               
               
                 332 
                 collector 
               
               
                 336 
                 gas inlet 
               
               
                 338 
                 gas outlet 
               
               
                 340 
                 inlet end 
               
               
                 342 
                 outlet end 
               
               
                 344 
                 body 
               
               
                 345 
                 sidewall 
               
               
                 349 
                 end face 
               
               
                 350 
                 outer peripheral surface 
               
               
                 352 
                 weld bead 
               
               
                 354 
                 outer surface 
               
               
                 360 
                 welded joint