HEAT RECOVERY SYSTEM AND HEAT EXCHANGER
An exhaust gas heat recovery system may include a housing, a valve member, and a heat exchanger. The housing may include an inlet, an outlet, a first exhaust gas pathway in communication with the inlet and outlet, and a second exhaust gas pathway in communication with the inlet and outlet. The valve member may be disposed within the housing and may be movable between first and second positions. In the first position, the valve member may allow fluid flow through the first exhaust gas pathway and substantially prevent fluid flow through the second exhaust gas pathway. In the second position, the valve member may allow fluid flow through the second exhaust gas pathway. The heat exchanger may be in communication with the second exhaust gas pathway and may include a conduit containing a fluid in thermal communication with exhaust gas when the valve member is in the second position.
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This application claims the benefit of U.S. Provisional Application No. 61/772,578, filed on Mar. 5, 2013. The entire disclosure of the above application is incorporated herein by reference.
FIELD OF THE INVENTIONThe present disclosure relates to a compact heat exchanger and a flow control assembly, and more particularly, an automotive exhaust heat recovery system and heat exchanger.
BACKGROUNDThis section provides background information related to the present disclosure and is not necessarily prior art.
A significant amount (e.g., approximately one-third) of energy in fuel consumed by an internal combustion engine is lost as heat rejected through an exhaust system associated with the internal combustion engine. It is desirable to recover this heat or thermal energy from exhaust gas flowing through the exhaust system for various purposes. For example, such recovered thermal energy can be used to heat vehicle fluids to provide faster passenger cabin warm-up and windshield defrosting. Additionally or alternatively, the recovered thermal energy can be used to improve fuel economy by reducing friction and viscous losses in the vehicle lubrication systems, for example in the engine, transmission, or transaxle, by increasing the temperature of the corresponding lubricants in those systems.
Recovering the heat from exhaust gases can pose technical challenges with respect to the heat recovery device, especially with the heat exchanger. The heat recovery system must overcome harsh operating conditions (e.g., heat, oxidation, and corrosion) while extracting a desired amount of heat with minimal backpressure. Additional constraints are applied to this scenario when the requirements for compact size, light weight, and low cost are needed for implementation into automobiles. Additionally, the ability to have a bypass mode where the back pressure and heat transfer are minimized may be desirable for some engine operating conditions or vehicle applications.
SUMMARYThis section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
The present disclosure provides a heat exchanger assembly disposed in an exhaust gas stream that may recover thermal energy from the exhaust gas stream. The heat exchanger assembly may be coupled with a valve element that can be controlled to regulate a flow of exhaust gas through either or both of a heat exchanger flow path and a bypass flow path that bypasses the heat exchanger flow path. The valve element may be controlled by an external actuator and may be positioned depending upon operating conditions of the exhaust gases, working limits of the heat exchanger, and/or demand for thermal energy recovery, for example. The heat exchanger flow path and the bypass flow path may terminate in a common collector which has an outlet to connect with the remainder of the exhaust system. The assembly can be placed at any location within the exhaust stream. Locations relatively close to the engine may have the potential to provide the heat exchanger with the hottest exhaust gas temperatures, which may increase an amount of thermal energy that the assembly is able to recover. However, the higher the exhaust gas temperature the more demanding it is for the durability of the heat recovery system due to the increased thermal loading.
The controllable heat recovery assembly can be used with an internal combustion engine, such as in an automobile, for example, or any other combustion engine. Recovered thermal energy may be used for rapid warm-up of engine coolant to aid in faster windshield defrosting, improved HVAC (heating, ventilation and air conditioning) system performance for accelerated passenger cabin warm up, and/or to improve fuel economy by reducing viscous losses through heating of various fluid systems in the vehicle, such as engine oil and transmission fluid, for example. Further uses of the recovered thermal energy may include steam generation for power generation (e.g., in Rankine cycle systems). It will be appreciated that the heat exchangers disclosed herein could be used with thermoelectric devices to generate electricity from the thermal energy in the exhaust gases.
During some periods of operation of the engine, it may not be desirable to extract energy from the exhaust system. During these periods it may be desirable to route exhaust gases through a bypass flow path. It may be desirable to minimize any heat transfer from the exhaust gases to the working fluid during bypass flow operation. During other operating conditions, when heat extraction is desirable, some or all of the exhaust gas may be diverted through a flow path including the heat exchanger. The routing of exhaust gas may be controlled in such a way that it is throttled or adjusted to a certain percentage of flow through each of the bypass and heat exchanger flow paths. In some embodiments, a control module may send electronic signals to an actuator driving the valve assembly to control and adjust a position of the valve assembly based on operating conditions and parameters of various engine and vehicle systems and subsystems. In some embodiments, a thermally controlled actuator may be used to control the position of the valve assembly. Such a thermally controlled actuator could include a wax valve, a thermostat device, and/or any other device configured to actuate the valve assembly in response to exhaust gases, coolant and/or any other fluid reaching one or more predetermined thermal states.
Regulation of the exhaust flows through the bypass and heat exchanger flow paths allows for control over the amount of heat energy that is able to be recovered or extracted from the exhaust gases. Heat energy recovery from the exhaust gas may be desirable following a start-up of the engine, for example. Under cold start-up conditions, it may be desirable to maximize heat extraction from the exhaust gases in order to warm up the engine coolant, to speed up windshield defrost, and/or heat-up a passenger compartment of the vehicle, for example. Accelerated heat-up of the engine coolant also decreases the time-averaged engine oil viscosity, resulting in lower viscous losses in the moving parts of the engine and reduced fuel consumption. Alternatively, under high speed and/or high load engine operating conditions, it may be desirable to reduce or minimize the thermal extraction from the exhaust gases so that excessive heat does not have to be carried and rejected by the engine/vehicle cooling system.
In some embodiments, the assembly of the present disclosure transfers heat from exhaust gases to additional or alternative vehicle fluids, such as lubricants for an engine, a transmission, an axle, and/or a differential, for example, and/or any other fluid.
Control of the heat extraction can also be employed for other reasons in a vehicle. For example, if the heat extraction system is located upstream of an emissions device such as a catalytic converter or lean NOx trap, then it may be desirable to maintain the temperature of the exhaust gases entering that emissions device within a specific temperature range. The temperature range may depend upon the conversion efficiency of the emissions device and service temperature limits for long life and durability of the device. In this type of application, it may be desirable to reduce or prevent heat extraction from the exhaust gases when the emissions device is below operating temperature so that the emissions device heats up as quickly as possible to an optimal operating temperature. Likewise, it can be desirable to extract heat energy from the exhaust gases, even under conditions of high engine speed and/or load, to keep the operating temperature of an emissions device below an upper operating temperature threshold to prevent damage and/or maintain the efficiency of the emissions device.
In some forms, the present disclosure provides an exhaust gas heat recovery system that may include a housing, a valve member, and a heat exchanger. The housing may include an inlet, an outlet, a first exhaust gas pathway in communication with the inlet and the outlet, and a second exhaust gas pathway in communication with the inlet and the outlet. The valve member may be disposed within the housing and may be movable between a first position and a second position. In the first position, the valve member may allow fluid flow through the first exhaust gas pathway and substantially prevent fluid flow through the second exhaust gas pathway. In the second position, the valve member may allow fluid flow through the second exhaust gas pathway. The heat exchanger may be in communication with the second exhaust gas pathway and may include a conduit having a fluid flowing therein. The fluid may be in thermal communication with exhaust gas in the heat exchanger when the valve member is in the second position and may be substantially thermally isolated from the exhaust gas when the valve member is in the first position. The heat exchanger may be substantially fluidly isolated from the first exhaust gas pathway when the valve member is in the first portion.
In other forms, the present disclosure provides an exhaust gas heat recovery system that may include a housing, a valve member, and a heat exchanger. The housing may include an inlet, an outlet, a first exhaust gas pathway in communication with the inlet and the outlet, and a second exhaust gas pathway in communication with the inlet and the outlet. The valve member may be disposed within the housing and may be movable between a first position allowing fluid flow through the first exhaust gas pathway and a second position allowing fluid flow through the second exhaust gas pathway. The heat exchanger may be in communication with the second exhaust gas pathway and may include a conduit having a fluid flowing therein. The fluid may be in thermal communication with exhaust gas in the heat exchanger when the valve member is in the second position. The housing may include a first stop member contacting a leading end of the valve member when the valve member is in the first position and a second stop member contacting a trailing end of the valve member when the valve member is in the first position. The leading end may contact a surface of the first stop member that faces generally away from the first exhaust gas pathway.
In some embodiments, the first exhaust gas pathway is substantially aligned with the inlet and the outlet to define a substantially linear flow path therethrough. In some embodiments, the valve member at least partially defines a substantially U-shaped flow path through the heat exchanger when the valve member is in the second position, the valve member defining an inlet into the U-shaped flow path and an outlet out of the U-shaped flow path when the valve member is in the second position.
The present disclosure also provides a heat exchanger that operates within such a heat recovery system. The heat exchanger may utilize a U-shaped flow path through which the exhaust gases may flow when the heat recovery system is operating in a heat recovery mode. The construction of the heat exchanger is designed to provide good durability under severe thermal operating conditions while still providing good performance for heat transfer at low pressure drop. In some embodiments, parallel cooling plates of the heat exchanger are arranged in a manner that is perpendicular to an axis about which a rotary valve member rotates. Heat transfer fins may be arranged between the cooling plates to increase heat transfer from the exhaust gases. Cooling plate coolant headers may be located in opposite corners of the heat exchanger along an edge of the cooling plates distal to the valve body. Features may be provided in the cooling plates to uniformly distribute coolant throughout the cooling cavity.
In some embodiments, the heat exchanger is configured for high temperature applications. In such embodiments, cooling plates may be arranged perpendicular to the rotary valve member axis, and one or more surfaces of the cooling plates are textured with heat transfer enhancing geometric features. The coolant headers in these embodiments may be located on or near a centerline of the cooling plates, adjacent to each other and proximate to the valve body to form a distinct U-shaped flow path through which the exhaust gases flow. Features may be provided in the cooling plates to uniformly distribute coolant throughout the cooling cavity.
In some embodiments, a cooling plate arrangement is provided whereby the cooling plates are parallel to the valve plate when the valve plate is in the bypass position. In such embodiments the cooling plates may be contained in an outer shell which may also form the exhaust gas headers on both the inlet and outlet sides of the gas pathway through the heat exchanger.
In some embodiments, the exhaust gas heat recovery system heats two fluid streams from the exhaust gas. In some embodiments, an exhaust gas recirculation (EGR) cooler is combined and/or operate in concert with an exhaust gas heat recovery (EGHR) system. In some embodiments, the exhaust gas heat recovery system includes a gas to gas heat exchanger arrangement.
In some embodiments, an inlet and an outlet of the valve body may be in communication with an exhaust manifold associated with an engine and substantially all of the exhaust gas that flows through the exhaust manifold may flow through the inlet and the outlet.
In another form, the present disclosure provides another system for recovering heat from exhaust gas of an internal combustion engine. The system may include a body, a valve member and a heat exchanger. The body may include an inlet, an outlet, a first exhaust gas pathway in communication with the inlet and the outlet, and a second exhaust gas pathway in communication with the inlet and the outlet. The body may be adapted to receive exhaust gas from the internal combustion engine. The valve member may be disposed within the body and may be movable between a first position allowing fluid flow through the first exhaust gas pathway and restricting fluid flow through the second exhaust gas pathway and a second position allowing fluid flow through the second exhaust gas pathway. The heat exchanger may be in communication with the second exhaust gas pathway and may include first, second, third and fourth cooling plates arranged parallel to each other. The first and second cooling plates may define a first working fluid cavity therebetween. The third and fourth cooling plates may define a second working fluid cavity therebetween. The second and third cooling plates may define a first exhaust passage therebetween. The first cooling plate may define a second exhaust passage that is parallel to the first exhaust passage. The first and second exhaust passages may be in communication with the second exhaust gas pathway.
In some embodiments, the heat exchanger includes a housing in which the first, second, third and fourth cooling plates are disposed. The housing may include a working fluid inlet and a working fluid outlet in fluid communication with the first and second working fluid cavities.
In some embodiments, the first, second, third and fourth cooling plates are arranged parallel to a direction of fluid flow through the first exhaust gas pathway.
In some embodiments, the heat exchanger includes first and second deflector plates disposed within the housing at respective first and second opposing edges of the first, second, third and fourth cooling plates.
In some embodiments, the housing includes a proximal end attached to the body and a distal end opposite the proximal end. The working fluid inlet and the working fluid outlet may be disposed in respective corners of the housing at or near the distal end.
In some embodiments, the first working fluid cavity defines first and second generally U-shaped flow paths extending from the working fluid inlet and providing working fluid to the working fluid outlet, the first U-shaped flow path is disposed within the second U-shaped flow path.
In some embodiments, the heat exchanger includes first and second ribs defining the first generally U-shaped flow path and defining the second generally U-shaped flow path. At least one of the first and second ribs may include leakage openings through which working fluid leaks between the first and second generally U-shaped flow paths.
In some embodiments, the first rib is generally U-shaped and the second rib is generally straight.
In some embodiments, the heat exchanger includes first and second fin packs attached to the second and third cooling plates, respectively, and disposed in the first and second exhaust passages, respectively.
In some embodiments, the housing includes a proximal end attached to the body and a distal end opposite the proximal end. The working fluid inlet and the working fluid outlet may be disposed along a line extending between the distal and proximal ends and guide exhaust gas in a U-shaped path through the heat exchanger.
In some embodiments, each of the first, second and third cooling plates include a plurality of dimples protruding into one of the first and second exhaust passages.
In some embodiments, the system includes a deflector attached to edges of the first, second, third and fourth cooling plates adjacent the body. The deflector may prevent leakage of exhaust gas between the valve member and the edges of the first, second, third and fourth cooling plates when the valve member is in the second position. The valve member may abut the deflector in the second position.
In some embodiments, the heat exchanger includes a deflector plate and a housing in which the cooling plates are disposed. The deflector plate may be disposed within the housing and may include a plurality of slots receiving the cooling plates. Each of the slots may be defined by a corresponding pair of resiliently flexible tabs that grip edges of the cooling plates.
In some embodiments, the tabs may be arranged to increase a grip on the edges of the cooling plates in response to movement of the deflector plate relative to the cooling plates.
In another form, the present disclosure provides another system for recovering heat from exhaust gas of an internal combustion engine. The system may include a body, a valve member and a heat exchanger. The body may include an inlet, an outlet, a first exhaust gas pathway in communication with the inlet and the outlet, and a second exhaust gas pathway in communication with the inlet and the outlet. The body may be adapted to receive exhaust gas from the internal combustion engine. The valve member may be disposed within the body and movable between a first position allowing fluid flow through the first exhaust gas pathway and restricting fluid flow through the second exhaust gas pathway and a second position allowing fluid flow through the second exhaust gas pathway. The heat exchanger may be in communication with the second exhaust gas pathway and may include a plurality of cooling plates arranged parallel to each other and defining an exhaust passage and a working fluid passage. The exhaust passage may define a generally U-shaped flow path therethrough. The working fluid passage may include first and second generally U-shaped flow paths receiving working fluid from a working fluid inlet and providing working fluid to a working fluid outlet. The first U-shaped flow path may be disposed within the second U-shaped flow path. A divider may define the first and second generally U-shaped flow paths and may include leakage openings through which working fluid leaks between the first and second generally U-shaped flow paths.
In some embodiments, the plurality of cooling plates includes first, second, third and fourth cooling plates. The first and second cooling plates may define the working fluid passage therebetween. The third and fourth cooling plates may define another working fluid passage therebetween. The second and third cooling plates may define the exhaust passage therebetween. The first cooling plate may define another exhaust passage.
In some embodiments, the heat exchanger includes another divider that defines the first and second generally U-shaped flow paths and includes leakage openings through which working fluid leaks between the first and second generally U-shaped flow paths.
In some embodiments, one of the dividers is generally U-shaped and the other divider is generally straight.
In some embodiments, the cooling plates are arranged parallel to a direction of fluid flow through the first exhaust gas pathway.
In some embodiments, the heat exchanger includes a housing in which the cooling plates are disposed.
In some embodiments, the heat exchanger includes first and second deflector plates disposed within the housing at respective first and second opposing edges of the cooling plates.
In some embodiments, the housing includes a proximal end attached to the body and a distal end opposite the proximal end. The working fluid inlet and the working fluid outlet may be disposed in respective corners of the housing at or near the distal end.
In some embodiments, the heat exchanger includes a fin pack disposed between adjacent cooling plates and disposed in the exhaust passage.
In some embodiments, the housing includes a proximal end attached to the body and a distal end opposite the proximal end. The working fluid inlet and the working fluid outlet may be disposed along a line extending between the distal and proximal ends and guide exhaust gas in a U-shaped path through the heat exchanger.
In some embodiments, at least one of the cooling plates includes a plurality of dimples protruding into the exhaust passage.
In some embodiments, the system includes a deflector attached to edges of the cooling plates adjacent the body. The deflector may prevent leakage of exhaust gas between the valve member and the edges of the cooling plates when the valve member is in the second position. The valve member may abut the deflector in the second position.
In some embodiments, the heat exchanger includes a deflector plate and a housing in which the cooling plates are disposed. The deflector plate may be disposed within the housing and may include a plurality of slots receiving the cooling plates. Each of the slots may be defined by a corresponding pair of resiliently flexible tabs that grip edges of the cooling plates.
In some embodiments, the tabs may be arranged to increase a grip on the edges of the cooling plates in response to movement of the deflector plate relative to the cooling plates.
In another form, the present disclosure provides another system for recovering heat from exhaust gas of an internal combustion engine. The system may include first and second valve assemblies and a heat exchanger. The first valve assembly may include a first valve body and a first valve member. The first valve body may include a first inlet, a first outlet and a first opening. The first inlet may be configured to receive exhaust gas from the internal combustion engine. The first valve member may be disposed within the first valve body and may be movable relative thereto between a first bypass position and a first heat exchange position. The first valve member restricts fluid communication between the first inlet and the first opening in the first bypass position and allows fluid communication among the first inlet, the first opening and the first outlet in the first heat exchange position. The second valve assembly may include a second valve body and a second valve member. The second valve body may include a second inlet, a second outlet and a second opening. The second inlet may be configured to receive a fluid from a fluid source. The second valve member may be disposed within the second valve body and may be movable relative thereto between a second bypass position and a second heat exchange position. The second valve member restricts fluid communication between the second inlet and the second opening in the second bypass position and allows fluid communication among the second inlet, the second opening and the second outlet in the second heat exchange position. The heat exchanger may be attached to and disposed between the first and second valve bodies and may include an exhaust gas passageway and a fluid passageway. The exhaust gas passageway may be in fluid communication with the first opening and may receive exhaust gas from the first inlet when the first valve member is in the first heat exchange position. The fluid passageway may be in fluid communication with the second opening and may receive fluid from the second inlet when the second valve member is in the second heat exchange position. The fluid passageway may be fluidly isolated from the exhaust gas passageway and may be in a heat transfer relationship with the exhaust gas passageway.
In some embodiments, the heat exchanger includes first and second plates and first and second fin packs. The second fin pack may be disposed between the first and second plates.
In some embodiments, the first plate and the first fin pack may define a first portion of the exhaust gas passageway. The first plate and the second fin pack may define a first portion of the fluid passageway. The second fin pack and the second plate may define a second portion of the exhaust gas passageway.
In some embodiments, the heat exchanger includes an outer housing encasing the first and second plates and the first and second fin packs. The first and second valve bodies may be attached to opposing first and second ends of the outer housing.
In some embodiments, the first valve assembly and the heat exchanger cooperate to define a first U-shaped flow path. The second valve assembly and the heat exchanger may cooperate to define a second U-shaped flow path.
In some embodiments, the first and second U-shaped flow paths are misaligned with each other by one-hundred-eighty degrees.
In some embodiments, the fluid is air and the fluid source is an HVAC duct.
In some embodiments, the fluid is air and the fluid source is an air-induction duct supplying air to the engine.
In another form, the present disclosure provides another system for recovering heat from exhaust gas of an internal combustion engine. The system may include a valve assembly and a heat exchanger. The valve assembly may include a valve body and a valve member. The valve body may include an inlet, an outlet and an opening. The inlet may be configured to receive exhaust gas from the internal combustion engine. The valve member may be disposed within the valve body and movable relative thereto between a bypass position and a heat exchange position. The valve member restricts fluid communication between the inlet and the opening in the bypass position and allows fluid communication among the inlet, the opening and the outlet in the heat exchange position. The heat exchanger may be attached to the valve body and may include an exhaust gas passageway, a first fluid passageway and a second fluid passageway. The first and second fluid passageways may be fluidly isolated from each other and from the exhaust gas passageway. The exhaust gas passageway may be in heat transfer relationships with the first and second fluid passageways.
In another form, the present disclosure provides another system for recovering heat from exhaust gas of an internal combustion engine. The system may include a valve assembly and a heat exchanger. The valve assembly may include a valve body and first and second valve members. The valve body may include an inlet, an outlet, a first volume, a second volume, a first opening and a second opening. The inlet may be configured to receive exhaust gas from the internal combustion engine and supply the exhaust gas to the first and second volumes. The first valve member may be disposed within the first volume and may be movable relative thereto between a first bypass position and a first heat exchange position. The first valve member restricts fluid communication between the first volume and the first opening in the first bypass position and allows fluid communication among the inlet, the first volume, the first opening and the outlet in the first heat exchange position. The second valve member may be disposed within the second volume and may be movable relative thereto independently of the first valve member between a second bypass position and a second heat exchange position. The second valve member restricts fluid communication between the second volume and the second opening in the second bypass position and allows fluid communication among the inlet, the second volume, the second opening and the outlet in the second heat exchange position. The heat exchanger may be attached to the valve body and may include first and second exhaust gas passageways and first and second fluid passageways. The first and second fluid passageways may be fluidly isolated from each other and from the first and second exhaust gas passageways. The first and second exhaust gas passageways may be in heat transfer relationships with the first and second fluid passageways, respectively. The first and second exhaust gas passageways may be substantially thermally isolated from the second and first fluid passageways, respectively.
In some embodiments, the valve body includes an interior dividing wall that separates the first and second volumes.
In another form, the present disclosure provides another system for recovering heat from exhaust gas of an internal combustion engine. The system may include a valve assembly and a heat exchanger. The valve assembly may include a valve body and a valve member. The valve body may include an inlet, an outlet and an opening. The inlet may be configured to receive exhaust gas from the internal combustion engine. The valve member may be disposed within the valve body and may be movable relative thereto between a bypass position and a heat exchange position. The valve member restricts fluid communication between the inlet and the opening in the bypass position and allows fluid communication among the inlet, the opening and the outlet in the heat exchange position. The heat exchanger may be attached to the valve body and may include an exhaust gas passageway and a fluid passageway. The fluid passageway may be fluidly isolated from the exhaust gas passageway. The exhaust gas passageway may be in a heat transfer relationship with the fluid passageway. The exhaust gas passageway may include an inlet and first and second outlets. The inlet may receive exhaust gas from the opening in the valve body. The first outlet may provide exhaust gas to the outlet of the valve body. The second outlet may provide exhaust gas to an exhaust gas recirculation conduit.
In some embodiments, the first outlet of the heat exchanger is disposed at a first end of the heat exchanger and the second outlet of the heat exchanger is disposed at a second end of the heat exchanger opposite the first end.
In some embodiments, the exhaust gas recirculation conduit includes a valve movable between a first position allowing exhaust gas from the exhaust gas passageway to exit the heat exchanger through the second outlet and a second position restricting exhaust gas from the exhaust gas passageway from exiting the heat exchanger through the second outlet.
In some embodiments, the exhaust gas recirculation conduit provides exhaust gas to an induction system of the engine.
In another form, the present disclosure provides another system for recovering heat from exhaust gas of an internal combustion engine. The system may include a valve assembly and a heat exchanger. The valve assembly may include a valve body and a valve member. The valve body may include an inlet, an outlet and an opening. The inlet may be configured to receive exhaust gas from the internal combustion engine. The valve member may be disposed within the valve body and movable relative thereto between a bypass position and a heat exchange position. The valve member restricts fluid communication between the inlet and the opening in the bypass position and allows fluid communication among the inlet, the opening and the outlet in the heat exchange position. The heat exchanger may be attached to the valve body and may include cooling plates defining an exhaust gas passageway and a fluid passageway. The fluid passageway may be fluidly isolated from the exhaust gas passageway. The exhaust gas passageway may be in a heat transfer relationship with the fluid passageway. The heat exchanger may also include a deflector plate and a housing in which the cooling plates are disposed. The deflector plate may be disposed within the housing and may include a plurality of slots receiving the cooling plates. Each of the slots may be defined by a corresponding pair of resiliently flexible tabs that grip edges of the cooling plates.
In some embodiments, the tabs are arranged to increase a grip on the edges of the cooling plates in response to movement of the deflector plate relative to the cooling plates.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Example embodiments will now be described more fully with reference to the accompanying drawings. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, and devices, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
When an element or layer is referred to as being “on,” “engaged to,” “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
With reference to
The valve assembly 16 may be of one of the types disclosed in Assignee's commonly owned United States Patent Application Publication No. 2012/0017575, the disclosure of which is hereby incorporated by reference in its entirety. As will be subsequently described, a valve plate 80 of the valve assembly 16 may be movable between a bypass position (
The valve assembly 16 may include a valve body 50, a main valve shaft 54, and the valve plate or diverter plate 80. The valve body 50 may house the main valve shaft 54 and diverter plate 80 and may be shaped so as to control and regulate the exhaust gas flow through the valve body 50 and heat exchange flow paths. The valve body 50 may include an inlet 51, an outlet 59, and one or more openings for fluid communication with the heat exchanger assembly 17.
The valve assembly 16 may be attached to the exhaust system by an inlet flange 52 and an outlet flange 53. The connection with the exhaust system may be by bolted flange, welded connection, or otherwise coupled. Similarly, the valve assembly 16 may be attached to the heat exchanger assembly 17 by welded interface (shown) or otherwise bolted or coupled, with or without a gasket. In this embodiment, the valve body 50 has a flange 55 for coupling with the heat exchanger assembly 17. The welded coupling provides the advantage of a leak-free seal, while the gasketed version of the coupling helps to reduce conductive heat transfer, especially if the gasket contains an insulating material. Coolant enters the heat exchanger assembly 17 through a working fluid inlet tube 57 and exits through a working fluid exit tube 58. In some operating environments it may be desirable to reverse the flow of working fluid through the heat exchanger assembly, depending on the construction of the heat exchanger assembly and the desired operating conditions of the heat exchanger (parallel flow or counter flow operation).
The position of the valve plate 80 may regulate exhaust gas flow through the EGHR system 10 downstream of the valve body inlet 51. The valve plate 80 may be a “butterfly” type (e.g., extending in both directions from axis of the main valve shaft 54) but the valve plate 80 may also be a “flap” type, extending in only one direction from the axis of the main valve shaft 54. The valve plate 80 is may be supported by a main shaft 54 on one side and a stub shaft 85 on the other. The valve plate 80 may also be cantilevered from a single end, the main valve shaft 54. The main valve shaft 54 and stub shaft 85 are supported by a bushing 81 or bearing surface, in cooperation with the valve housing 50. The choice of bushing and/or bearing material may depend on the application temperature and the material of the valve shaft(s) and valve body 50. An actuator (not shown) may rotate the main valve shaft 54 to move the valve plate 80 between the bypass and heat-exchange positions. Motion of the actuator may be controlled by a control module and may transferred to the main valve shaft 54 by means of an actuator arm, linkage, or any other suitable mechanism (not shown). The main valve shaft 54 is externally retained in axial position by a retaining washer 56.
During operation of the EGHR system 10, the exhaust gases enter into the valve body 50 and are directed into the bypass conduit and/or the heat exchanger assembly 17, depending on the position of the valve plate 80. Valve plate stop or seat features 87 may be formed into the valve body 50 to reduce or prevent unwanted leakage between the valve body 50 and the valve plate 80 when the valve plate 80 is in the heat-exchange position. The seat feature 87 for the valve plate 80 also provides a positive stop to limit the rotation of the valve plate 80 about the axis of the main valve shaft 54. This may allow some embodiments to employ a simple actuator without position control (or without fine position control). For example, in applications that do not require modulation of the position of the valve plate 80, a low-cost two-position actuator may be used.
The heat exchanger assembly 17 may include a plurality of coolant plates 100 that are perpendicular to a rotational axis of the main valve shaft 54 and substantially parallel to the bypass flow path between the valve body inlet 51 and the valve body outlet 59. This configuration may help to minimize back pressure through the EGHR system 10 when operating in heat exchange mode. A heat exchanger core may include a stack of interior cooling plates 100, along with a heat exchanger front coolant plate 95 and a heat exchanger back coolant plate. The front coolant plate 95 and the back coolant plate may or may not be identical to the interior cooling plates 100. The cooling plates are arranged such that there is a coolant cavity 104 (
In one embodiment of the heat exchanger assembly 17, the first cooling cavity 104 may be formed between the front coolant plate 95 and the adjacent interior cooling plate 100. Similarly, the last cooling cavity in the heat exchanger core is formed between the back coolant plate and its adjacent interior cooling plate 100. The sub-assembly of cooling plates is held within the heat exchanger housing 91 by welded or brazed coupling around the cooling inlet and outlet tubes, 57 and 58, respectively, and at other coupling zones 105 where the front cover plate 98 is coupled with the front cooling plate 95 and similarly the back cover plate is coupled with the back cooling plate. The placement of the coupling zones 105 are selected to be in relatively cooler areas of the heat exchanger and located to allow differential movement between the heat exchanger core and the front and rear cover plates without inducing stresses between the heat exchanger housing and the heat exchanger core. This method of having selective coupling between the heat exchanger housing and the front and back cooling plates was found to have the least thermal durability issues when fin packs 83 are used in the exhaust gas passageways between the cooling plates to enhance heat transfer from the exhaust gases.
A side deflector plate 99 is used on both sides of the heat exchanger between the heat exchanger side cover plate 96 and the cooling plates 100, primarily in the region adjacent to the fin packs 83. The function of the side deflector plate 99 is to prevent exhaust gases from bypassing the fin packs 83 by filling in the spaces between the edges of the cooling plates 100, and between the edge of the fin pack 83 and the side cover plate 96. The side deflector plates 99 can also serve to locate and hold the cooling plates 100 together during the manufacturing process. A top deflector plate 82 is used on the top side of the cooling plates 100 between the heat exchanger and the valve assembly 16. The top deflector plate 82 prevents unwanted exhaust gas leakage along the top edge of the cooling plates 100 and also provides a stop and sealing surface for the valve plate 80 when in the heat exchange position.
Joining of all the components in the assembly can be achieved either through laser welding, brazing, or a combination of these two methods. It is conceivable that the components could also be joined through any other combination of processes such as soldering, other welding methods, gluing, and similar.
The exhaust gas flow path 132 through the EGHR system (in the heat exchange mode) is illustrated in
Ideally, the fin packs 83 are located in place during assembly with at least one locator protrusion 121 in the cooling plates 100. The locator protrusion 121 extends outward from the cooling cavity into the exhaust gas passageway between the cooling plate pairs. The entire second portion of the heat exchanger cooling plates may or may not be covered with heat transfer enhancing geometric features 135 to increase heat transfer in the regions of the cooling plates not directly adjacent to the fin packs 83. The fin packs 83 can be made of a variety of heat transfer surfaces such as lanced offset strip fin packs (
The side deflector plates 99 are used to prevent exhaust gases from bypassing the fin packs 83. The side deflector plates 99 (
As shown in
In
An alternative fin structure, such as that shown in
The flow path of the working fluid or coolant through the cooling cavity between cooling plates 100 is shown in
The areas where the coolant diverter features from one cooling plate touch the coolant diverter features on its mating cooling plate serve to reinforce the structure of the heat exchanger core and prevent collapsing of the cooling cavity in the event of an overpressure situation on the exhaust gas side or an under-pressure situation on the cooling cavity side. Similarly, features such as the coolant header lands 133, the fin packs 83, and the fin pack locator protrusions 121 may cooperate between cooling plate pairs to prevent the cooling plates 100 from buckling due to situations where the coolant pressure is higher than the exhaust gas pressure.
Another series of heat exchanger embodiments for an EGHR system are disclosed in
In the heat exchanger 17 embodiment shown in
The interior cooling plates 303 are located during assembly with the side deflector plates 318. The side deflector plates 318 prevent the exhaust gases from bypassing the heat transfer surfaces by filling in the gap around the cooling plate 303 edges near the side cover plate 308. As seen in
The top deflector plate 317 performs the same function in the present embodiment as the embodiment shown in
In
In
An additional feature which may be found on any of the heat exchanger embodiments disclosed here is the internal heat shield 372 as detailed in
The placement of the coolant inlet and outlet headers adjacent to each other on the centerline of the cooling plate also poses an interesting problem in how to evenly distribute the coolant over the nearly rectangular cooling plate 303 surface. A symmetric system of coolant diversion ribs 320 was developed through a series of computational fluid dynamics simulations as shown in
One key feature of all of the heat exchanger embodiments disclosed in
The embodiments disclosed in
The schematic shown in
In the heat exchanger assembly 402 of
A solution to control the heat transfer to each of the working fluids in a two working fluid EGHR system is shown in
The valve body assembly of
An example of an integrated EGHR-EGR system is shown in
An air-to-air heat exchange schematic is shown in
The physical embodiment of the air-to-air EGHR system can be seen in
For ease of construction, one gas control valve assembly 650 is welded to the heat exchanger 652 and the second gas control valve assembly 651 is joined to the heat exchanger with a gasket (not shown) and fasteners 612 at a bolted flange 611. Other combinations of joining the first and second gas control valves to the heat exchanger 652 could be employed. A side cover 630 surrounds the heat exchanger plates 631 and fin packs 609 and 607 to cooperate with the valve assemblies 650 and 651 to enclose both fluid streams.
The heat exchanger plate 631 is shown alone in
For clarity as to the assembly of heat exchanger plates 631 and fin packs 609 and 607,
Another EGHR assembly 700 is shown in
The heat exchanger assembly of
An alternative embodiment to the heat exchanger shown in
The EGHR valve housings described here may be manufactured as a single, integrally formed component and may be cast or fabricated from wrought materials. A material from which the valve housing is formed may be selected depending on a range of temperatures and/or other operating conditions that the EGHR system may be operating under in a given application. For applications in which the material of the valve housing will reach temperatures of about eight-hundred degrees Celsius (800° C.) during operation of the EGHR system, the valve housing may be formed from a ferritic cast iron, for example. For applications in which the material of the valve housing will reach temperatures of more than eight-hundred degrees Celsius (800° C.) during operation of the EGHR system, the valve housing may be formed from austenitic cast iron or a heat-resistant steel, for example. The valve shaft and valve diverter plate may be formed from a steel alloy such as a heat-resistant wrought steel, for example, and/or any other suitable material.
The heat exchanger assemblies may include a heat exchanger core defining generally parallel exhaust gas flow channels in communication with the heat exchange conduits in the valve housing. The exhaust gas flow channels may direct the exhaust gases in a two-pass, generally U-shaped flow path when the diverter plate is in the heat-exchange position. This allows the exhaust gas to contact more surface area of the entire heat exchanger core. A first portion of the exhaust gas flow channels may be formed by a part of the heat exchanger core disposed upstream of the diverter plate and the second portion of the exhaust gas flow channels may be formed by a part of the heat exchanger core disposed downstream of the diverter plate.
When the valve diverter plate is in the bypass position, exhaust gases may enter the valve housing through the inlet opening and may flow through the bypass conduit to bypass the heat exchanger assembly. In this operating mode, little or no heat will be transferred from the exhaust gas to the working fluid in the heat exchanger assembly.
An additional benefit of the EGHR valve assemblies shown here is that the potential for internal exhaust gas leakage around the diverter plate and through the heat exchanger core is low when the diverter plate is in the bypass position. This potential for internal leakage is low because the pressure drop through the bypass conduit is minimal, thus minimizing the root cause that could drive unwanted flow past the diverter plate and into the heat exchanger core. This internal flow leakage is undesirable because it would increase heat transfer between the exhaust gases and the heat exchanger working fluid when it is unwanted. Furthermore, if and when exhaust gases do leak past the valve diverter plate and into the heat exchanger core when the valve diverter plate is in the bypass position, minimal unwanted heat transfer will result because the leaked gases may be prevented from flowing past the diverter plate a second time to reach the outlet opening.
Furthermore, the substantial lack of leakage around the diverter plate in the bypass position and the physical separation between the bypass conduit and the heat exchanger assembly allows the flow of exhaust gas entering the inlet opening to flow through the valve housing in a manner that substantially thermally isolates the exhaust gas from the working fluid in the heat exchanger assembly. Accordingly, very little or no heat transfer may occur therebetween in the bypass mode when such heat transfer may be undesirable. If any small amount of leakage past the diverter plate were to occur when the diverter plate is in the bypass position, the velocity of flow once the exhaust gas leaked past the diverter plate would be very low and would be prevented or restricted from flowing into the heat exchanger assembly or leaking past the diverter plate a second time and reaching the outlet opening.
The EGHR systems presented here can be utilized as an independent or self-contained system that can be inserted into an exhaust gas stream wherever there is sufficient packaging space. It should be noted that these EGHR systems can be integrated into other components in the exhaust system.
While the following examples and discussion generally relate to exhaust gas heat recovery applications, the general concepts discussed herein are also applicable to other “exhaust applications” such as thermal protection of exhaust components, or EGR systems, for example. The principles of the present disclosure can be employed in exhaust systems associated with internal or external combustion systems for stationary or transportation applications. It will be appreciated that an assembly including the valve housings and heat exchangers described above may be used to transfer heat between other fluids in other applications (e.g., charge air cooling applications, lubricant heating applications, etc.). Therefore, the principles of the present disclosure are not limited in application to transferring heat from engine exhaust gas to a working fluid. In some embodiments, the valve assembly and heat exchanger could be used to transfer heat between a working fluid and ambient air or air to be drawn into an engine for combustion.
In some embodiments, the EGHR systems may be configured to transfer heat from exhaust gases directly or indirectly to additional or alternative vehicle fluids, such as lubricants for an engine, a transmission, an axle, and/or a differential, for example, and/or any other fluid. For example, a lubricant or other fluid may flow into the heat exchanger core of the heat exchanger assembly to absorb heat from the exhaust gas when the diverter plate is not in the bypass position. In this manner, the EGHR system may transfer heat from exhaust gas to the lubricant and/or other fluid to optimize a viscosity of the fluid, for example, to improve the performance and/or fuel-economy of the vehicle.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
Claims
1. A system for recovering heat from exhaust gas of an internal combustion engine, the system comprising:
- a body including an inlet, an outlet, a first exhaust gas pathway in communication with the inlet and the outlet, and a second exhaust gas pathway in communication with the inlet and the outlet, the body adapted to receive exhaust gas from the internal combustion engine;
- a valve member disposed within the body and movable between a first position allowing fluid flow through the first exhaust gas pathway and restricting fluid flow through the second exhaust gas pathway and a second position allowing fluid flow through the second exhaust gas pathway; and
- a heat exchanger in communication with the second exhaust gas pathway and including first, second, third and fourth cooling plates arranged parallel to each other, the first and second cooling plates defining a first working fluid cavity therebetween, the third and fourth cooling plates defining a second working fluid cavity therebetween, the second and third cooling plates defining a first exhaust passage therebetween, the first cooling plate defining a second exhaust passage that is parallel to the first exhaust passage, the first and second exhaust passages are in communication with the second exhaust gas pathway.
2. The system of claim 1, wherein the heat exchanger includes a housing in which the first, second, third and fourth cooling plates are disposed, the housing includes a working fluid inlet and a working fluid outlet in fluid communication with the first and second working fluid cavities.
3. The system of claim 2, wherein the first, second, third and fourth cooling plates are arranged parallel to a direction of fluid flow through the first exhaust gas pathway.
4. The system of claim 3, wherein the heat exchanger includes first and second deflector plates disposed within the housing at respective first and second opposing edges of the first, second, third and fourth cooling plates.
5. The system of claim 4, wherein the housing includes a proximal end attached to the body and a distal end opposite the proximal end, and wherein the working fluid inlet and the working fluid outlet are disposed in respective corners of the housing at or near the distal end.
6. The system of claim 5, wherein the first working fluid cavity defines first and second generally U-shaped flow paths extending from the working fluid inlet and providing working fluid to the working fluid outlet, the first U-shaped flow path is disposed within the second U-shaped flow path.
7. The system of claim 6, wherein the heat exchanger includes first and second ribs defining the first generally U-shaped flow path and defining the second generally U-shaped flow path, at least one of the first and second ribs including leakage openings through which working fluid leaks between the first and second generally U-shaped flow paths.
8. The system of claim 7, wherein the first rib is generally U-shaped and the second rib is generally straight.
9. The system of claim 6, wherein the heat exchanger includes first and second fin packs attached to the second and third cooling plates, respectively, and disposed in the first and second exhaust passages, respectively.
10. The system of claim 4, wherein the housing includes a proximal end attached to the body and a distal end opposite the proximal end, and wherein the working fluid inlet and the working fluid outlet are disposed along a line extending between the distal and proximal ends and guide exhaust gas in a U-shaped path through the heat exchanger.
11. The system of claim 10, wherein each of the first, second and third cooling plates include a plurality of dimples protruding into one of the first and second exhaust passages.
12. The system of claim 1, further comprising a deflector attached to edges of the first, second, third and fourth cooling plates adjacent the body, the deflector preventing leakage of exhaust gas between the valve member and the edges of the first, second, third and fourth cooling plates when the valve member is in the second position, and wherein the valve member abuts the deflector in the second position.
13. A system for recovering heat from exhaust gas of an internal combustion engine, the system comprising:
- a body including an inlet, an outlet, a first exhaust gas pathway in communication with the inlet and the outlet, and a second exhaust gas pathway in communication with the inlet and the outlet, the body adapted to receive exhaust gas from the internal combustion engine;
- a valve member disposed within the body and movable between a first position allowing fluid flow through the first exhaust gas pathway and restricting fluid flow through the second exhaust gas pathway and a second position allowing fluid flow through the second exhaust gas pathway; and
- a heat exchanger in communication with the second exhaust gas pathway and including a plurality of cooling plates arranged parallel to each other and defining an exhaust passage and a working fluid passage, the exhaust passage defining a generally U-shaped flow path therethrough, the working fluid passage including first and second generally U-shaped flow paths receiving working fluid from a working fluid inlet and providing working fluid to a working fluid outlet, the first U-shaped flow path is disposed within the second U-shaped flow path, wherein a divider defines the first and second generally U-shaped flow paths and includes leakage openings through which working fluid leaks between the first and second generally U-shaped flow paths.
14. The system of claim 13, wherein the plurality of cooling plates includes first, second, third and fourth cooling plates, the first and second cooling plates defining the working fluid passage therebetween, the third and fourth cooling plates defining another working fluid passage therebetween, the second and third cooling plates defining the exhaust passage therebetween, the first cooling plate defining another exhaust passage.
15. The system of claim 14, wherein the heat exchanger includes another divider defining the first and second generally U-shaped flow paths and including leakage openings through which working fluid leaks between the first and second generally U-shaped flow paths.
16. The system of claim 15, wherein one of the dividers is generally U-shaped and the other divider is generally straight.
17. The system of claim 13, wherein the cooling plates are arranged parallel to a direction of fluid flow through the first exhaust gas pathway.
18. The system of claim 13, wherein the heat exchanger includes a housing in which the cooling plates are disposed.
19. The system of claim 18, wherein the heat exchanger includes first and second deflector plates disposed within the housing at respective first and second opposing edges of the cooling plates.
20. The system of claim 19, wherein the housing includes a proximal end attached to the body and a distal end opposite the proximal end, and wherein the working fluid inlet and the working fluid outlet are disposed in respective corners of the housing at or near the distal end.
21. The system of claim 20, wherein the heat exchanger includes a fin pack disposed between adjacent cooling plates and disposed in the exhaust passage.
22. The system of claim 18, wherein the housing includes a proximal end attached to the body and a distal end opposite the proximal end, and wherein the working fluid inlet and the working fluid outlet are disposed along a line extending between the distal and proximal ends and guide exhaust gas in a U-shaped path through the heat exchanger.
23. The system of claim 22, wherein at least one of the cooling plates includes a plurality of dimples protruding into the exhaust passage.
24. The system of claim 13, further comprising a deflector attached to edges of the cooling plates adjacent the body, the deflector preventing leakage of exhaust gas between the valve member and the edges of the cooling plates when the valve member is in the second position, and wherein the valve member abuts the deflector in the second position.
Type: Application
Filed: Feb 26, 2014
Publication Date: Sep 11, 2014
Applicant: Wescast Industries, Inc. (Brantford)
Inventor: Clayton A. Sloss (Paris)
Application Number: 14/190,648
International Classification: F01N 5/02 (20060101);