US20040226694A1

US20040226694A1 - Heat exchanger with removable core

Info

Publication number: US20040226694A1
Application number: US10/439,088
Authority: US
Inventors: Roland Dilley; Richard Beldam; Willi Smith
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2003-05-14
Filing date: 2003-05-14
Publication date: 2004-11-18

Abstract

There is provided a heat exchanger, such as an exhaust gas cooler, that has a removable core at least partially disposed in a shell. Tubes extending through the shell fluidly connect tanks at both ends of the shell so that thermal energy can be transferred between a first fluid in the shell and a second fluid in the tubes. At least one of the tanks is defined partially by a tube sheet, and the tank is structured to be moved axially through the shell in a direction toward the opposite tank and removed from the shell with the tubes. A sealing member is disposed between the movable tank and the shell to prevent fluid from flowing therebetween.

Description

FIELD OF THE INVENTION

The present invention relates generally to a heat exchanger with a removable core and, more particularly, the invention relates to a heat exchanger with a tank that is axially adjustable, for example, as the components of the heat exchanger expand or contract due to thermal changes.

BACKGROUND OF THE INVENTION

Heat exchangers are often used to transfer thermal energy between two or more fluids. For example, hot engine fluids such as oil, water, and exhausted combustion gases that are generated by or circulated through an internal combustion engine can be circulated through a heat exchanger to transfer thermal energy to a coolant, thereby cooling the hot engine fluid. The heat exchanger can be subjected to significant thermal stresses due to the extreme temperatures and temperature variations occurring in the heat exchanger. The thermal stresses can interfere with the operation of the heat exchanger and shorten the life of the heat exchanger, thereby increasing the risk of damage to other components and requiring costly repair or replacement.

One conventional heat exchanger features a tubular outer shell with opposing tanks mounted at the two opposite open ends of the shell. A plurality of tubes extend through the outer shell to connect the tanks. A first fluid can be circulated between the tanks and a second fluid can be circulated through the shell so that thermal energy is exchanged between the two fluids through the walls of the pipes. One of the tanks can be partially defined by a floating plate to which the tubes are attached.

The floating plate is not rigidly connected to the shell but rather is sealed to the inner surface of the shell by an o-ring so that the tube moves freely in the axial direction of the shell. The tank with the floating plate can be connected to the shell so that the floating plate moves axially within the tank, or the tank can be connected to the floating plate, i.e., not connected to the shell, so that the entire tank moves axially with the floating plate. In either case, as the tubes are heated or cooled and change in length, the floating plate moves axially accordingly, thereby reducing thermal stresses in the tubes.

The increased size and complexity of heat exchangers generally increases the costs of manufacture and maintenance. As the number of components and welds or other joints increases, the likelihood of manufacturing errors generally increases. Further, disassembly of a heat exchanger can be difficult and time consuming. For example, if the tubes or other internal components fail, disassembly requires the removal of the tanks from the tubes and removal of the tubes from the shell. In some cases, the cost and complexity of disassembly makes repairs impractical.

Thus, there exists a need for an improved heat exchanger that reduces thermal stresses. Preferably, the number of components and required joints should be minimized to simplify the manufacture of the heat exchanger. Further, a core portion of the heat exchanger should be removable during disassembly of the heat exchanger.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: [0007]
FIG. 1 is section view illustrating a heat exchanger with a removable core according to one embodiment of the present invention; [0008]
FIG. 2 is an enlarged view illustrating the sealing member of the heat exchanger of FIG. 1, as indicated in FIG. 1; and [0009]
FIG. 3 is a section view of a sealing member according to another embodiment of the present invention.[0010]

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. [0011]
Referring now to FIG. 1, there is shown a heat exchanger according to one embodiment of the present invention. The heat exchanger [0012] 10 has an outer shell 20 and a replaceable core 40 that is disposed at least partially therein, the core 40 being structured to allow for thermal expansion independent of the shell 20. The heat exchanger 10 can be, for example, an exhaust gas cooler (EGC) as shown in FIG. 1 that uses a fluid coolant such as water or oil to cool hot exhaust gases flowing from an engine. The heat exchanger 10 can similarly be used for cooling or heating other fluids, including liquids and gases.
The [0013] shell 20 of the heat exchanger 10 is tubular and extends axially from a first end 22 to a second end 24 and defines an interior space 26 and one or more ports 28, 30 for passing a fluid, for example, the coolant. As shown in FIG. 1, the inlet coolant port 28 receives the coolant, and the coolant then flows through the shell 20 and exits through the outlet coolant port 30. Baffles 16 can be provided within the shell to direct the flow and increase the speed of the coolant in the shell 20. The shell 20 can be cylindrical, as shown, or the shell 20 can have a cross-sectional shape defined by other polygons, such as a square. First and second tanks 50, 60 are provided at the respective ends 22, 24 of the shell 20. Tubes 80 or other fluid connection means that extend between the first and second tanks 50, 60 provide fluid communication therebetween for another fluid, for example, the hot exhaust gas. As the hot exhaust gas flows between the tanks 50, 60 through the tubes 80, thermal energy from the hot exhaust gas is transferred to the coolant, thereby cooling the hot exhaust gas.
The first tank [0014] 50 is defined by a first tube sheet 52 and a tank member 54. The tube sheet 52 defines a plurality of holes, which correspond to the tubes 80, so that the tubes 80 are fluidly connected to the tank 50. The tank 50 also has a port 56 through which the hot exhaust gas from the engine enters the heat exchanger 10. The tube sheet 52 and the tank member 54 are connected to the shell 20, for example, by bolts 12 that extend through the tank member 54, through the tube sheet 52, and into threaded holes in the shell 20. The bolts 12 are shown to extend in a direction parallel to the axial direction of the shell 20 in FIG. 1, though other configurations are also possible. For example, the bolts 12 can extend transverse to the axial direction of the shell 20 or at an angle to the axial direction. Alternatively, the tank 50 can be connected to the shell 20 by other connection devices, such as clips, clamps, and the like. In addition, gaskets 14 can be provided between the tube sheet 52 and the shell 20 and/or between the tube sheet 52 and the tank member 54. The gaskets 14, which can be formed of stainless steel or other resilient and/or corrosion resistant materials, seal the connections between the tube sheet 52, shell 20, and tank member 54. Further, the gaskets 14 provide a flexible connection between the tube sheet 52, shell 20, and tank member 54 to accommodate slight changes in the shape or size of the components, for example, as the components heat and cool.
Similarly, the [0015] second tank 60 is defined by a second tube sheet 62 and a second tank member 64. The second tube sheet 62 also defines a plurality of holes that correspond to the tubes 80 so that the tubes 80 fluidly connect the second tank 60 to the first tank 50. The second tank 60 has a port 66 through which the cooled exhaust gas can exit the heat exchanger 10. Thus, the exhaust gas enters the first tank 50 through the first port 56, flows through the tubes 80 in the shell 20 to the second tank 60, and exits the heat exchanger 10 through the second port 66. In other embodiments, the exhaust gas can flow in the opposite direction through the heat exchanger 10. Further, the exhaust gas can flow in both directions between the tanks 50, 60 and can flow through the tubes 80 multiple times before exiting the heat exchanger 10, as is known in the art. For example, the first tank 50 can be partitioned into two portions, and the second port 66 can be provided on the first tank 50 so that the exhaust gas flows into a first portion of the first tank 50, through some of the tubes 80 to the second tank 60, and then through other tubes 80 to the second portion of the first tank 50, where the exhaust gas exits the heat exchanger 10 through the second port 66. Thus, the exhaust gas can be made to flow through the shell 20 twice, thereby increasing the thermal transfer between the exhaust gas and the coolant.
The [0016] second tank 60 is not rigidly connected to the shell 20. Instead, the second tank 60 is configured to adjust axially relative to the shell 20 as the tubes 80 thermally expand or contract and change length, or the components of the heat exchanger 10 otherwise change size or shape. As shown in FIG. 2, the second tank member 64 is formed of a tubular portion 68 and an end portion 70, which are welded together or otherwise connected, for example, by bolts, clamps, an interference fit, or a mechanical interlock such as a snap fit. The second tube sheet 62 is connected to the tubular portion 68, and the tubes 80 are connected to the second tube sheet 62. One or more sealing members 72, such as o-ring seals, are disposed between the shell 20 and the tubular portion 68 of the second tank.
The sealing [0017] members 72 can be disposed in grooves 74 defined on an inner surface 32 of the shell 20. The sealing members 72 fluidly disconnect the interior space 26 from a space exterior to the shell, thereby preventing the coolant in the shell 20 from exiting the shell 20 through a junction between the shell 20 and the second tank 60. The junction of the shell 20 and the second tank 60 that is sealed by the sealing members 72 can define an annular space therebetween or the shell 20 and the second tank 60 can be in contact.
The [0018] second tank 60, including the tank member 64 and the tube sheet 62, is connected to the tubes 80 to form the core 40, which is removable from the shell 20, for example, for repair, maintenance, or replacement. Advantageously, the second tank 60 can be smaller than the inside diameter of the shell 20 so that the core 40 can be removed as a unitary structure from the first end 22 of the shell 20. For example, the core 40 can be removed by removing the bolts 12 and the first tank member 50, then sliding the second tank 60 axially toward the first end 22 of the shell 20 and removing the second tank 60 with the tubes 80, baffles 16, and the first tube sheet 52. Thus, the core 40, comprising the second tank member 64, tube sheets 52, 62, tubes 80, and baffles 16 can be fixedly attached, e.g., by weld joints, braze joints, solder joints, and the like, and can be removed from the shell 20 as a unitary structure. Further, the exhaust gas can be fluidly contained in the tanks 50, 60 and tubes 80 so that the exhaust gas does not contact the sealing members 72, thereby reducing the heating effect of the exhaust gas on the sealing members 72. As shown in the figures, the sealing members 72 may also advantageously be located adjacent a portion of second tank member 64 that is not directly exposed to the exhaust gas, but is rather exposed to fluid coolant and/or a space exterior to the shell.
As shown in FIG. 3, the sealing [0019] members 72 can be disposed on the second tank, for example, in grooves 76 defined by the tubular portion 68 of the tank member 64 of the second tank 60. The inner surface 32 of the shell 20 can have a diameter that corresponds in size to the outer surface of the second tank 60, for example, the tubular portion 68 thereof, so that the sealing members 72 seal the inner surface 32 to the outer surface of the second tank 60. Further, a portion 34 of the inner surface 32 proximate the second end 24 of the shell 20 can flare radially outward in a direction toward the first end 22 of the shell 20, i.e., the inner surface portion 34 is tapered toward the second end 24. Thus, the second tank 60 can easily be slid axially through the shell 20 during assembly, and the inner surface portion 34 provides a close fit with the second tank 60 so that the sealing members 72 seal therebetween.
The [0020] shell 20 can be a cast member, for example, formed of cast steel, and the inner surface portion 34 can be a machined surface on the shell 20 with precise tolerances. The shell casting can also define other features such as the ports 28, 30, grooves 74, a bracket 36 or other device for mounting the heat exchanger 10, and the like. The other components, such as the tank members 54, 64, tube sheets 52, 62, and baffles 16, can be formed of corrosion resistant materials such as stainless steel, and can be stamped, machined, or otherwise formed.
Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. [0021]

Claims

That which is claimed:

1. A heat exchanger with a removable core, the heat exchanger comprising:

a tubular shell extending between first and second ends and defining an interior space for receiving a first fluid;

a core comprising:

a first tank at the first end of the shell;

a second tank at the second end of the shell, the second tank and shell defining a junction therebetween; and

a plurality of fluid-conducting members extending between the first and second tanks and fluidly connecting the first and second tanks such that a second fluid disposed in the tanks is fluidly disconnected from the interior space of the shell; and

a sealing member disposed between the shell and the core such that the core is free to adjust axially relative to the shell and the sealing member prevents fluid from flowing through the junction between the core and the shell,

wherein the core is structured to be axially moved through the shell in a direction from the second end toward the first end of the shell and removed therefrom as a unit.

2. A heat exchanger according to claim 1 wherein the shell defines inlet and outlet ports for circulating the first fluid.

3. A heat exchanger according to claim 1 wherein the second tank comprises a second tank member fixedly attached to a tube sheet, the tube sheet defining a plurality of holes corresponding to the tubes.

4. A heat exchanger according to claim 3 wherein the second tank member is attached to the second tube sheet by at least one of the group that includes a weld joint, a braze joint, and a solder joint.

5. A heat exchanger according to claim 1 wherein the sealing member comprises at least one elastic o-ring.

6. A heat exchanger according to claim 1 wherein at least one of an inner surface of the shell and an outer surface of the second tank defines at least one groove for receiving the sealing member.

7. A heat exchanger according to claim 1 wherein the sealing member fluidly disconnects the interior space of the shell from an exterior of the shell and the sealing member is fluidly disconnected from the second fluid in the second tank.

8. A heat exchanger according to claim 7 wherein the sealing member is adjacent a portion of the second tank that is fluidly disconnected from the second fluid.

9. A heat exchanger according to claim 1 wherein the first tank is removably connected to the shell.

10. A heat exchanger according to claim 1 further comprising a resilient member disposed between the shell and the first tank such that the first tank is flexibly connected to the shell.

11. A heat exchanger according to claim 1 wherein the shell defines a tapered inner surface having an inner surface portion proximate the second end with a diameter that corresponds in size to an outer surface of the second tank such that the sealing member forms a fluid seal therebetween.

12. An exhaust gas cooler with a removable core, the exhaust gas cooler comprising:

a tubular shell extending between first and second ends, the shell defining an interior space and at least one port for receiving a coolant;

a first tank at the first end of the shell, the first tank being defined at least partially by a first tube sheet, the first tank defining at least one port for receiving a hot exhaust gas;

a second tank at the second end of the shell, the second tank being defined at least partially by a second tube sheet and a second tank member fixedly attached to the second tube sheet, the second tank and shell defining an annular junction therebetween;

a plurality of tubes extending between the first and second tube sheets and fluidly connecting the first and second tanks such that the exhaust gas flows therebetween;

a sealing member disposed between the shell and the second tank such that the second tank is configured to adjust axially relative to the shell and the sealing member prevents the coolant fluid from flowing through the junction between the second tank and the shell,

wherein the second tank is structured to be axially moved through the shell in a direction from the second end toward the first end of the shell and removed therefrom.

13. An exhaust gas cooler according to claim 12 wherein the second tank member is attached to the second tube sheet by at least one of the group that includes a weld joint, a braze joint, a solder joint, a bolt, a clamp, an interference fit, and a mechanical interlock.

14. An exhaust gas cooler according to claim 12 wherein the sealing member comprises at least one elastic o-ring.

15. An exhaust gas cooler according to claim 12 wherein at least one of an inner surface of the shell and an outer surface of the second tank defines at least one groove for receiving the sealing member.

16. An exhaust gas cooler according to claim 12 wherein the sealing member fluidly disconnects the interior space in the shell from an exterior of the shell and the sealing member is fluidly disconnected from the second fluid in the second tank.

17. An exhaust gas cooler according to claim 16 wherein the sealing member is adjacent a portion of the second tank that is fluidly disconnected from the second fluid.

18. An exhaust gas cooler according to claim 12 wherein the tube sheets, the tubes, and the second tank are removable from the shell as a unitary structure.

19. An exhaust gas cooler according to claim 12 wherein the first tube sheet is bolted to the shell.

20. An exhaust gas cooler according to claim 12 further comprising a resilient member disposed between the shell and the first tube sheet such that the first tube sheet is flexibly connected to the shell.

21. An exhaust gas cooler according to claim 12 wherein the shell defines an inner surface portion proximate the second end having a diameter that corresponds in size to an outer surface of the second tank, the inner surface portion flaring radially outward in a direction toward the first end of the shell.

22. A heat exchanger with a removable core, the heat exchanger comprising:

a shell means for receiving a first fluid;

first and second tank means for receiving a second fluid, the first and second tank means being configured proximate to first and second ends of the shell means respectively, and the shell means and second tank means defining a junction therebetween;

a connection means for fluidly connecting the first and second tank means; and

sealing means for preventing the first fluid from flowing through the junction between the shell means and the second tank means,

wherein the connection means and the second tank means are configured to adjust axially relative to the shell means and to be removed through the first end of the shell means.