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Publication numberUS20060124283 A1
Publication typeApplication
Application numberUS 11/011,895
Publication dateJun 15, 2006
Filing dateDec 14, 2004
Priority dateDec 14, 2004
Publication number011895, 11011895, US 2006/0124283 A1, US 2006/124283 A1, US 20060124283 A1, US 20060124283A1, US 2006124283 A1, US 2006124283A1, US-A1-20060124283, US-A1-2006124283, US2006/0124283A1, US2006/124283A1, US20060124283 A1, US20060124283A1, US2006124283 A1, US2006124283A1
InventorsHind Abi-Akar, Chris Scolton
Original AssigneeHind Abi-Akar, Chris Scolton
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Fluid-handling apparatus with corrosion-erosion coating and method of making same
US 20060124283 A1
Abstract
Inlet surfaces of a fluid-handling apparatus, such as a heat exchanger, are often prone to corrosion and erosion due to the high velocities of incoming fluid. The present disclosure includes a fluid-handling apparatus with a plurality of wetted surfaces of which a first portion is corrosion-erosion prone and a second portion is non-corrosion-erosion prone. The first portion is coated with a corrosion-erosion coating that is harder than the first portion. Less than all of the wetted surfaces are coated.
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Claims(20)
1. A fluid-handling apparatus comprising:
an apparatus body including a plurality of wetted surfaces characterized in that a first portion of the wetted surfaces is corrosion-erosion prone and a second portion of the wetted surfaces is non-corrosion-erosion prone;
a corrosion-erosion resistant coating coated on the first portion of the wetted surfaces, wherein the coating is harder than the apparatus body; and
wherein less than all of the wetted surfaces are coated.
2. The fluid-handling apparatus of claim 1 wherein the coating includes a metal alloy with a coefficient of thermal expansion sufficiently similar to a coefficient of thermal expansion of the first portion of the wetted surface so that the coating remains attached over a pre-determined temperature range.
3. The fluid-handling apparatus of claim 1 wherein the coating includes a metal alloy being galvanic compatible with the first portion of the wetted surfaces.
4. The fluid handling apparatus of claim 1 wherein the coating includes a copper-based alloy.
5. The fluid-handling apparatus of claim 4 wherein the coating includes copper-nickel alloys including a nickel concentration less than or equal to 40% and greater than or equal to 9%.
6. The fluid-handling apparatus of claim 5 wherein the coating includes a nickel concentration of 9-11%.
7. The fluid-handling apparatus of claim 4 wherein the coating includes an aluminum bronze alloy including an aluminum concentration equal to or less than 14%, a manganese concentration equal to or less than 2%, a nickel composition equal to or less than 6%, and an iron concentration equal to or less than 5%.
8. The fluid handling apparatus of claim 1 wherein the first portion of the wetted surfaces includes at least one liquid inlet surface.
9. The fluid-handling apparatus of claim 1 wherein the apparatus includes a heat exchanger.
10. The fluid-handling apparatus of claim 9 wherein the heat exchanger includes an air-sea water heat exchanger.
11. The fluid-handling apparatus of claim 10 wherein the apparatus body defines a plurality of sea water passages separated from one another by at least one sea water fin and a plurality of air passages separated from one another by at least one air fin oriented substantially perpendicular to the sea water fin, and the sea water passages being separated from the air passages by a plurality of separator plates; and
the sea water passages and air passages being fluidly connected to a sea water inlet manifold and a air inlet manifold, respectively.
12. The fluid-handling apparatus of claim 11 wherein the first portion of the wetted surfaces includes at least one sea water inlet surface within at least the sea water inlet manifold, and the second portion of the wetted surfaces includes a inner surface of the sea water passages; and
the coating includes a metal alloy being galvanic compatible with the first portion of the wetted surfaces and including a coefficient of thermal expansion sufficiently similar to a coefficient of thermal expansion of the first portion of the wetted surface so that the coating remains attached over a pre-determined temperature range, and the coating including either a copper-nickel alloy with 9-40% nickel and an aluminum bronze alloy.
13. An engine system using sea water as a coolant comprising:
an engine; and
a heat exchanger being in fluid communication with the engine, and defining a sea water inlet fluidly connected with a plurality of wetted surfaces, and a first portion of the wetted surfaces being corrosion-erosion prone and a second portion of the wetted surfaces being non-corrosion-erosion prone; a corrosion-erosion resistant coating being coated on the first portion of the wetted surfaces, and wherein the coating is harder than the first portion; and less than all the wetted surfaces are coated.
14. The engine system of claim 13 wherein the first portion includes at least one sea water inlet surface of the heat-exchanger.
15. The engine system of claim 14 wherein the coating includes a metal alloy being galvanic compatible with the first portion of the wetted surfaces and including a coefficient of thermal expansion sufficiently similar to a coefficient of thermal expansion of the first portion of the wetted surface so that the coating remains attached over a pre-determined temperature range.
16. The engine system of claim 15 wherein the coating includes a copper-based alloy.
17. The engine system of claim 16 wherein the coating includes a copper-nickel alloy including 9-40% nickel.
18. A method of making a heat exchanger, comprising the steps of:
assembling a plurality of components to include a plurality of wetted surfaces;
distinguishing between corrosion-erosion prone wetted surfaces and non-corrosion-erosion prone wetted surfaces; and
coating the corrosion-erosion prone wetted surfaces with a corrosion-erosion resistant coating being harder than the corrosion-erosion prone wetted surfaces.
19. The method of claim 18 wherein the step of coating includes the step of thermal spraying the coating onto the corrosion-erosion prone portion of the wetted surfaces.
20. The method of 18 wherein the step of coating being performed after the step of assembling.
Description
TECHNICAL FIELD

The present invention relates generally to fluid-handling apparatuses, and more specifically to heat exchangers with a corrosive-erosion resistant coating and a method of making same.

BACKGROUND

There are various uses for heat exchangers known in the art. For instance, heat exchangers, often referred to as charge air coolers, use a coolant to cool compressed air exiting a turbocharger before the air is injected into an engine. In commercial or pleasure marine crafts, sea water is often used as the coolant. The sea water will flow into a sea water inlet manifold before flowing into a plurality of sea water passages, and the air will flow into an air inlet manifold before flowing into a plurality of air passages. The sea water passages are generally oriented perpendicularly to the air passages such that the heat within the air can be exchanged with sea water through walls of the sea water and the air passages. The sea water passages and the air passages are defined by a core of the heat exchanger. The sea water will increase in temperature and the air will decrease in temperature as the sea water and air simultaneously pass through the core of heat exchanger.

Using sea water as the coolant can present a challenge due to the sea water's corrosive nature and tendency to contain abrasives such as sand and silt and other forms of deposits including sea weeds, sea shell fragments, animal components, etc. As the sea water flows from the inlet manifold into the plurality of smaller sea water passages, the flow of the sea water is turbulent. Thus, the sea water will directly contact at a relatively high velocity inlet surfaces defining the sea water inlet manifold before flowing into the sea water passages. Due to the high velocity and the corrosive nature of the sea water, the sea water contacting the inlet surfaces will impinge the surfaces. The impingement can cause corrosion and erosion, and thus, damage the surfaces of the inlet manifold, including a core surface defining inlets of the sea water passages. Over time, the damage can lead to holes, causing leakage of the sea water and, thus, premature failure of the heat exchanger. For instance, the corrosion and erosion can create holes in the surfaces separating the hot air passages and the sea water inlet manifold or passages, causing leaking of the sea water into the air passages.

One method known in the art of avoiding heat exchanger failure due to inlet surface corrosion-erosion and impingement is to use robust materials that offer corrosion-erosion resistance. For instance, a heat exchanger set forth in U.S. Pat. No. 5,323,849, issued to Korczynski, Jr. et. al., on Jun. 28, 1994, includes sea water wetted heat exchanger components that are made from corrosion and erosion-resistant materials. Although the Korczynksi heat exchanger includes corrosion and erosion-resistant sea water inlet surfaces, the heat exchanger also includes other components, such as the tubes defining the sea water passages, made from corrosion-erosion resistant materials. However, the tubes are less prone to corrosion and erosion than the inlet surfaces. The sea water contacting the inlet surfaces is turbulent; whereas, the sea water flow through the tubes is generally laminar. The turbulent flow causes more impingement which leads to corrosion and erosion than does the laminar flow.

Manufacturing heat exchanger components from corrosion and erosion-resistant materials can be more costly than using traditional materials. Further, the corrosion-erosion resistant materials can introduce a heat transfer penalty due to their reduced thermal conductivity. Most of the heat transfer occurs through the material separating the air and sea water passages, which is also where there is the least amount of impingement and corrosion-erosion related problems due to the flow of the sea water. Thus, by manufacturing all of the sea water wetted components out of corrosion-erosion resistant materials, rather than just the corrosion-erosion prone sea water inlet surfaces, the cost of the heat exchanger and the heat transfer penalty is unnecessarily increased while potentially also reducing heat transfer performance.

The present disclosure is directed at overcoming one or more of the problems set forth above.

SUMMARY OF THE INVENTION

According to one aspect of the present disclosure, a fluid-handling apparatus includes a an apparatus body including a plurality of wetted surfaces of which a first portion is corrosion-erosion prone and a second portion is non-corrosion-erosion prone. The first portion of the wetted surfaces is coated with a corrosion-erosion resistant coating that is harder than the first portion. Less than all of the wetted surfaces are coated.

In another aspect of the present disclosure, an engine system with marine applications includes an engine fluidly connected to a heat exchanger. The heat exchanger defines a sea water inlet that is fluidly connected to a plurality of wetted surfaces of which a first portion is corrosion-erosion prone and a second portion is non-corrosion-erosion prone. The first portion is coated with a corrosion-erosion resistant coating that is harder than the first portion. Less than all of the wetted surfaces are coated.

In yet another aspect of the present disclosure, a heat exchanger is made by assembling a plurality of components to include a plurality of wetted surfaces. Corrosion-erosion prone wetted surfaces are distinguished from non-corrosion-erosion prone surfaces. The corrosion-erosion prone wetted surfaces are coated with a corrosion-erosion resistant coating that is harder than the corrosion-erosion prone wetted surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an engine system, according to the present disclosure;

FIG. 2 is a sectioned side diagrammatic representation of a heat exchanger within the engine system of FIG. 1;

FIG. 3 is an isometric view of a sectioned core of the heat exchanger of FIG. 2; and

FIG. 4 is a table of example corrosion-erosion resistant coatings applied to the heat exchanger within the engine system of FIG. 1.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a schematic representation of an engine system 10 for marine applications, according to the present disclosure. The engine system 10 includes an engine 11 that includes an engine housing 21 defining an air inlet 22. The engine system 10 also includes a turbocharger 12 that includes an air outlet 23 fluidly connected to the air inlet 22 of the engine 11 via an air line 15. The turbocharger 12 draws ambient air through an air filter 13 and into an air inlet 44 of the turbocharger 12. Within the turbocharger 12, the air is compressed and then delivered to the engine 10 via the air line 15. An upstream portion of the air line 15 fluidly connects a fluid-handling apparatus, being a heat exchanger 14, with the air outlet 23 of the turbocharger 12. A downstream portion of the air line 15 fluidly connects the heat exchanger 14 with the air inlet 22 of the engine 11. The heat exchanger 14 is also in fluid communication with a pump 18 that can supply sea water to the heat exchanger 14 via a sea water line 19. The heat exchanger 14 includes a heat exchanger body 24 that defines an air inlet 25, an air outlet 26, a sea water inlet 27 and a sea water outlet 28.

The temperature of the compressed air exiting the turbocharger 12 is significantly increased due to the compression within the turbocharger 12. Thus, the heat exchanger 14, often referred to as a charge air cooler, will cool the compressed air, via heat exchange with the sea water, before it is injected into the engine 11. Sea water is preferably used as the coolant due to its accessibility, abundance and lower temperatures, but it should be appreciated that the heat exchanger 10 could use various other coolants. By cooling the compressed air, the density of the air is increased, allowing more air, and thus more oxygen, to occupy the volume of the cylinder. When the cooled compressed air is injected into the engine 11, the increased amount of oxygen within the cylinder can burn, resulting in increased engine power. The exhaust created by the combustion within the engine 11 will continue to power the turbocharger 12, and the process can repeat itself. Although the present disclosure is illustrated for the engine system 10 including the turbocharger 12, it should be appreciated that the heat exchanger could be used for other cooling applications in engine systems with or without turbochargers. For instance, the heat exchanger could be used to cool hot exhaust exiting the combustion chamber of the engine.

Referring to FIG. 2, there is shown a sectioned side diagrammatic representation of the heat exchanger 14. A core 30 is positioned within a space defined by the heat exchanger body 24 (shown in FIG. 1). Although the core 30 is preferably a “bar and plate” style core 30, it should be appreciated that the present invention also contemplates the heat exchanger including a “tube and fin” style core of the type known in the art, or any other suitable heat exchange structure. The core 30 includes a core body 42 that defines a plurality of air passages 34 (shown in FIG. 3) and a plurality of sea water passages 36. The core body 42 and the heat exchanger body 24 define a sea water inlet manifold 16 and a sea water outlet manifold 17 that direct sea water streams into and out of the core 30, and a sea water middle manifold 20 that changes the direction of the sea water flow. The sea water inlet, outlet and middle manifolds 16, 17 and 20, each are defined by a housing surface 16 a, 17 a, 20 a and a core surface 16 b, 17 b and 20 b, respectively. The sea water passages 36 are in fluid communication with the sea water inlet 27 and the sea water outlet 28 via the sea water inlet manifold 16 and the sea water outlet manifold 17, respectively. As illustrated by the arrows, the sea water will flow through the inlet 27 into the sea water inlet manifold 16, through a first portion 36 a of the sea water passages 36 to the middle manifold 20 in which the sea water changes direction, through a second portion 36 b of sea water passages 36 and to the outlet 28 via the sea water outlet manifold 17. Although the sea water makes two passes through the illustrated core 30, the present disclosure contemplates use in heat exchangers through which the sea water makes any number of passes, including only one. It should also be appreciated that, although not shown, an air inlet manifold and air outlet manifolds are attached to opposite ends of the core 30 to which the sea water manifolds 1, 17 and 20 are not attached and direct the flow of the air into and out of the air passages 34.

Still referring to FIG. 2, the heat exchanger body 24, including the core body 42, include a plurality of wetted surfaces 43. In the illustrated heat exchanger 14, the plurality of wetted surfaces 43 include, but is not limited to, the core surfaces 16 b, 17 b and 20 b and the housing surfaces 16 a, 17 a and 20 a of the sea water manifolds 16, 17 and 20, and surfaces defining the sea water passages 36. A first portion 43 a of the wetted surfaces 43 are corrosion-erosion prone 43 a and a second portion 43 b of the wetted surfaces 43 are non-corrosion-erosion prone. Those skilled in the art will appreciate that, although all of the wetted surfaces 43 may be subjected to some corrosion and erosion due to the harsh environment caused by the sea water, the first portion 43 a of the wetted surfaces 43 subject to direct impingement from the high velocity flow of sea water is significantly more corrosion and erosion prone than the second portion 43 b subject to contact from less turbulent flow of the sea water. The first portion 43 a includes at least one sea water inlet surface 39. The surfaces 39 include the surfaces 16 a, 16 b and 20 a and 20 b of the inlet manifold 16 and the middle manifold 20 being that the manifolds 16 and 20 direct the sea water into the sea passages 36. Preferably, the core surfaces 17 b and the housing surfaces 17 a defining the outlet manifold 17 are also included within the first portion 43 a. Because the sea water flowing through the sea water passages 36 has a laminar flow, the sea water is not directly impinging the surfaces defining the sea water passages 36. Thus, the second portion 43 b that is non-corrosion-erosion prone includes the surfaces of the sea water fins 35 defining the sea water passages 36. Only the first portion 43 a of the wetted surfaces 43 is coated with a corrosion-erosion resistant coating 40, and thus, less than all of the wetted surfaces 43 are coated. The corrosion-erosion resistant coating 40 is harder than the corrosion-erosion prone portion 43 a. From one point of view, the corrosion prone surfaces are flow direction changing surfaces, whereas the non-corrosion prone surfaces are generally parallel to the local flow direction.

Referring to FIG. 3, there is shown an isometric view of a sectioned core 30 of the heat exchanger 14 in FIG. 2. The core body 42 includes multiple separator sheets 32, air fins 33 and sea water fins 35, although the present invention contemplates a heat exchanger including only one separator sheet positioned between an air fin and a sea water fin. The separator sheets 32 are preferably alternatively separated from one another by the air fins 33 and the sea water fins 35 in order to maintain the air flow separate from the sea water flow. The air fins 33 separate the air passages 34 from one another, and the sea water fins 35 define and separate the sea water passages 36 from one another. Thus, the sea water fins 35 include the non-corrosion-erosion prone surfaces 43 b. The air fins 33 are preferably oriented substantially perpendicularly to the sea water fins 35 such that the flow of the air transverses the flow of the sea water. Although it should be appreciated that some of the air passages and sea water passages can be oriented to one another at various angles, the air flow still transverses the sea water flow.

Further, the core body 42 includes long enclosure bars 37 that act as end surfaces for each sea water fin 35 and provide a surface for attaching the manifolds 16, 17, 20 to the core body 42. The core body 42 also includes short enclosure bars 38 (shown in FIG. 2) that act as end surfaces for each air fin 33 to protect the air fins 33 and air passages 34 from sea water. Side sheets 31 enclose ends of the core 30, and mountings, such as load stops 29, are attached to the side sheets 31 to provide a means of securing the heat exchanger 14 within the engine system 10. The separate components of the core 30 can be made into one unit by various methods known in the art, such as brazing the assembled core. Thus, the core surfaces 16 b, 17 b and 20 b (shown in FIG. 2) include surfaces of various components, including an outer surface of the short bars 38 separating the air fins 33 from the sea water manifolds 16, 17 and 20, edge surfaces of the separator sheets 32, edge surfaces of the long bars 37, and edge surfaces of the sea water fins 35.

Referring to FIGS. 1-3, in the illustrated heat exchanger 14, the sea water fins 35, the separator sheets 32, the long bars 37 and the short enclosure bars 38 are made from copper due to the heat transfer capability of the copper. Thus, the first portion 43 a being corrosion-erosion prone is generally made from copper. However, it should be appreciated that the present disclosure contemplates use with corrosion-erosion prone wetted surfaces made from metals other than copper. The coating 40 preferably includes a metal alloy that is similar to the metal of the corrosion-erosion prone surfaces 43 a, illustrated as copper. The coating 40 preferably is sufficiently similar to the surfaces 43 a such that the coating 40 and the corrosion-erosion prone wetted surfaces 43 a are galvanic compatible. Those skilled in the art will appreciate that the galvanic compatibility of the coating 40 and the surfaces 43 a is dependent on various factors, including, but not limited to, the difference in the galvanic potentials of the coating 40 and the surfaces 43 a, whether the coating 40 or the surface 43 a acts as an anode, the area of coating 40 compared to the area of the electrolyte, and the type of electrolyte, being sea water. Although the copper-nickel alloys set forth in FIG. 4 are slightly more noble than the copper surface on which they are coated, the alloys are sufficiently galvanic compatible with the surfaces 43 a. In each of the example coatings set forth in Table I, the coating 40 includes a metal alloy principally comprised of copper.

Further, the coating 40 preferably includes a metal alloy with a coefficient of thermal expansion sufficiently similar to a coefficient of thermal expansion of the corrosion-erosion prone portion 43 a of the wetted surfaces 43 so that the coating 40 remains attached over a pre-determined temperature range. The predetermined temperature range is the range of temperatures to which the corrosion-erosion prone surfaces 43 a are subjected. For instance, in the illustrated heat exchanger, the compressed air is entering the air passages 34 at approximately 200 C. and exiting the air passages 34 at approximately 40 C. Because the air flowing through the air passages 34 transverses the core surfaces 16 b, 17 b and 20 b, the sea water core surfaces 16 b, 17 b and 20 b are subject to temperature range of 49-200 C. The coating 40 is principally comprised of the same material as the surfaces 43 a, being copper. Those skilled in the art will appreciate that alloys other than copper alloys, such as certain stainless steel alloys, may be used within the coating 40 applied to the copper surfaces 43 a as long as the alloy include a similar coefficient of thermal expansion as copper.

The coating 40 is preferably 0.005 to 0.015 inches (127-381 micrometers), but can have a thickness between 0.003-0.02 inches (75-500 micrometers). The coating 40 should be sufficiently thick to withstand the impingement of the sea water, but not too thick to create a substantial heat transfer penalty, material waste and unnecessary expense.

Referring to FIG. 4, there is shown a table including five example compositions of the coating 40 applied to the heat exchanger 14. Although the coating 40 could include any type of material that is harder than the corrosion-erosion prone wetted surfaces 43 a, is galvanic compatible with the surfaces 43 a in the relevant cooling liquid (e.g. sea water) and has a similar coefficient of thermal expansion as the surfaces 43 a, such as certain stainless steel alloys, preferably the coating 40 includes a copper-based alloy. Preferably, the copper-based alloy includes a copper-nickel alloy with a nickel concentration between 9% and 40%. The copper can provide sufficient heat transfer between sea water and the air, and the nickel protects the corrosion-erosion prone surfaces 43 a from impingement that can lead to corrosion and erosion. The coating 40 with the nickel is harder than the corrosion-erosion prone surfaces 43 a upon which the coating 40 is applied. For instance, example coating 1 includes the preferred version of the coating 40 that includes a copper-nickel alloy with a nickel concentration of approximately 10%. Those skilled in the art will appreciate that example coating 1 is a commercially available alloy, specifically alloy 70600, often referred to as 90-10% copper nickel. In addition to the copper and nickel, example coating 1 includes other alloying metals, including iron and manganese. The iron contributes the corrosion resistance and the strength of the coating 40 a, and the manganese contributes to the stability of the coating 40 a. Moreover, because the coating 40 includes almost 90% copper, the coating 40 a is sufficiently similar to the copper manifold surfaces 16 a, 16 b, 17 a, 17 b, 20 a and 20 b to which the coating 40 a is applied. Thus, the coating 40 is galvanic compatible with the surfaces 43 a, thereby providing a stable coating 40 a even in relatively highly polluted waters, and will not expand at a sufficiently different rate than the surfaces 43 a despite the heat fluctuations within the heat exchanger 14. Also, example coating 1 is resistant to biological fowling in polluted waters.

Example coating 2 includes a copper-nickel alloy that includes approximately 70% copper and approximately 30% nickel. Those skilled in the art will appreciate that example coating 2 is a commercially available alloy, specifically alloy 71600, often referred to as 70-30% copper-nickel. Similar to example coating 1, in addition to the copper and nickel, example coating 2 includes other alloying metals, including iron and manganese. Example coating 2 is harder than the corrosion-erosion prone surfaces 43 a upon which the coating 40 is applied. Example coating 3 includes a 60% copper—40% nickel alloy. Example coating 3 is not a standard copper alloy, but rather a powder commercially available for physical disposition spray applications. Although coating 3 could include other minor alloying metals like those used in example 1 and example 2, coating 3 is illustrated as including 60% copper and 40% nickel. Although the coatings in examples 2 and 3 will protect the corrosion-erosion prone surfaces 43 a, the 60-40% copper—nickel alloys are generally more expensive than the 90-10% copper nickel alloys, as used in example 1. Moreover, example coatings 2 and 3 are less stable and more prone to fowling when coated on the copper surfaces 43 a than the preferred coating 40 of Example 1 in highly polluted waters.

Example coating 4 includes a 85-15% copper nickel alloy. Similar to example coatings 1-3, example coating 4 includes copper to transfer the heat between the air and the sea water, and nickel to resist impingement, thereby, providing corrosion and erosion resistance. Moreover, example coating 4 includes minor alloying metals and is commercially available as alloy 72200.

Example coating 5 includes an aluminum-bronze alloy that includes 14% or less aluminum, 2% or less manganese, 6% or less nickel, and 5% or less iron. The remaining concentration would include copper and/or other minor alloying elements. Those skilled in the art will appreciate that the example coating 5 could includes standard aluminum-bronze alloys commercially available could be used. Example coating 5 is a commercially available aluminum bronze alloy, being alloy 63000. The aluminum aids in corrosion resistance while the iron and nickel aids in impingement resistance. As with the other coatings 40 a-c, example coating 5 preferably includes manganese and iron.

INDUSTRIAL APPLICABILITY

Referring to FIGS. 1-3, a method of making the heat exchanger 14 will be discussed. Although the heat exchanger 14 is part of the engine system 10 with marine application and is a “bar and plate” type heat exchanger, those skilled in the art should appreciate that the method of the present disclosure could apply to various types of heat exchangers, including the “tube and fin” and “tube and shell” type, used in various applications. A plurality of components 32, 33, 31, 35, 37, 38, 16, 17, 20 are assembled to include the plurality of wetted surfaces 43. In the illustrated example, the plurality of air fins 33 are oriented perpendicularly to the plurality of sea water fins 35, and the air fins 33 and sea fins 35 are alternatively stacked and separated from one another with the separator sheets 32. The short bars 38 are positioned at the closed ends of the air fins 33 in order to protect the air fin 33 from the incoming sea water. The components 32, 33, 31, 35, 37, 38 comprising the core 30 are secured to one another generally through a method known in the art, brazing, although the present disclosure contemplates various methods of securing the components of the core 30 to one another.

After the core 30 is brazed, the corrosion-erosion resistant coating 40 is applied to less than all of the wetted surfaces 43. The corrosion-erosion prone surfaces 43 a are distinguished from the non-corrosion-erosion prone surfaces 43 b, and only the corrosion-erosion prone surfaces 43 a will be coated. Although the corrosion-erosion prone surfaces 43 a may differ between different types of heat exchangers, the corrosion-erosion prone surfaces 43 a includes the wetted surface 43 that are subjected to direct impingement from the high velocity flow of the sea water. The non-corrosion-erosion prone surfaces 43 b includes the wetted surfaces 43 with which the sea water does not directly impinge. The surfaces 16 a, 16 b, 20 a, 20 b, 17 a and 17 b are subjected to direct impingement due to the turbulent flow of the sea water in the manifolds 16, 17, 20 as the sea water flows into and out of the sea water passages 36; whereas, the surfaces of the sea fins 35 defining the sea passages 36 are not directly impinged by the sea water due to the laminar flow of the sea-water through the passages 36. In the illustrated heat exchanger 14, the sea water makes two passes through the core 30. Not only will the turbulent flow of the sea water within the inlet and outlet manifolds 16 and 17 cause the sea water to directly impinge the manifold surfaces 16 a, 17 a, 16 b and 17 b before being directed into and out of the sea water passages 36, the housing surface 20 a of the middle manifold 20 directs the sea water flow from the first portion 36 a to the second portion 36 b of the passages 36, and thus, is also subject to direct impingement. It should be appreciated that the present disclosure could apply to heat exchangers through which the sea water makes any number of passes, including only one pass. Regardless of the number of sea water manifolds, preferably the housing surfaces, along with the core surfaces, defining each manifold are coated. Thus, the coating 40 will be applied to the core surfaces 16 b, 17 b and 20 b and the housing surfaces 16 a, 17 a and 20 a, and not applied to the surfaces of the sea water fins 35 defining the sea water passages 36.

Preferably before attaching the heat exchanger body 24 to the core 30 and thus creating the manifolds 16, 17 and 20, the coating 40 is applied to the corrosion-erosion prone wetted surfaces 43 a, being the core surfaces 16 b, 17 b and 20 b and the housing surfaces 16 a, 17 a and 20 a. Because the core surface 16 b, 17 b, and 20 b are accessible after the core 30 is assembled and brazed, the coating 40 can be applied to the core 30, after assembly and brazing. Thus, it is not necessary that the coating 40 be able to withstand the brazing process. Moreover, the coating 40 can be applied to the housing surfaces 16 a, 17 a and 20 a before the housing 24 is attached to the core 30. Although the coating 40 can be applied by various methods, the coating 40 is preferably applied by thermal spraying the coating 40 on the surfaces 43 a. Those skilled in the art will appreciate that there are various methods of thermal spraying. Although any one of the conventional methods of thermal spraying could be used to coat the surfaces 43 a, preferably the coating 40 is applied by High Velocity Oxy Fuel (HVOF). The HVOF method allows the coating 40 to be applied with hand-held devices, including, but not limited to, spray guns, and does not require isolation in a chamber or vacuum environment. Further, the coating 40 can be applied with a uniform thickness without the need for post treatments, such as grinding or polishing, to only the intended surfaces, being the corrosion-erosion prone surfaces 43 a. Thus, using proper thermal spray methods, the coating 40 should not obstruct the assembled sea water passages 36. Those skilled in the art will appreciate that the corrosion-erosion prone surfaces 43 a must be prepared and cleaned in a conventional manner when using thermal spray coating methods.

Although the thickness of the coating 40 will vary depending on the composition of the coating 40 and the particular application of the heat exchanger 14, the thickness will generally be between 0.003-0.02 inches (75-500 micrometers) and preferably between 0.005-0.015 inches (127-381 micrometers). The coating 40 must be sufficiently thick to provide the needed impingement and corrosion-erosion resistance, but not too thick to adversely affect cost or heat transfer.

Once the core 30 is assembled and the core surfaces 16 b, 17 b and 20 b and the housing surfaces 16 a, 17 a and 20 a are coated, the core 30 can be attached to the housing 24 in a conventional manner. The present disclosure contemplates various methods of attaching the core 30 to the housing 24, including, but not limited to bolting and welding. In the illustrated embodiments, the housing 24 is welded to the core 30, and thus, the coating 40 should be able to sufficiently withstand the heat from the welding process. However, it should be appreciated that the joint design style and type of the heat exchanger may be such that a welding resistant coating may not be needed. The attached housing 24 and the core 30 define the manifolds 16, 17 and 20.

The present disclosure is advantageous because it provides a relatively inexpensive, corrosion-erosion resistant heat exchanger 14 that can be used in harsh environments, such as in sea water. Rather than making all of heat exchanger components that come into with sea water from an exotic relatively expensive corrosion-erosion resistant material, the present disclosure coats only the portion 43 a of the heat exchanger 14 that is most corrosion-erosion prone due to the sea water. Relatively inexpensive materials, such as copper, that transfer heat well can still be used in the non-corrosion-erosion prone portions 43 b, such as the sea water fins 35. Thus, the use of the coating 40 does not adversely affect the efficiency of the heat exchanger 14.

The coating 40 is sufficiently hard and corrosion-erosion resistant that the sea water will not interact or impinge the coating 40. Thus, the coating 40 can protect the surfaces 43 a from impingement, corrosion and erosion that can lead to holes within the surfaces 43 a, causing leakage of the sea water into the air passages 34 and premature failure. Thus, the life and durability of the heat exchanger 14 is increased by making the heat exchanger 14 corrosion-erosion resistant while not compromising the efficiency of the heat exchanger 14 or significantly increasing the cost of the heat exchanger 14. In fact, because of the increased durability, there is a significant decrease in heat exchanger down time and repair frequency, which reduces maintenance costs.

The present disclosure is further advantageous because the preferred coating 40 is stable even in highly polluted waters. Because the coating 40 is made out of a similar metal as the surfaces 43 a, the coating 40 is galvanic compatible with the surfaces 43 a. Moreover, even if subjected to extreme temperature change, the coating 40 will adhere to the surfaces 43 a due to the similar coefficients of thermal expansion between the coating 40 and the surfaces 43 a.

Further, the coating 40 can be applied with relative ease. Because the corrosion-erosion prone surfaces 43 a on which the coating 40 is needed are accessible on the assembled core 30, there is no need to apply the coating 40 pre-assembly. Thus, there is no concern about the coating's ability to withstand the brazing of the core 30. In addition, by thermal spraying the coating 40 onto the surfaces 43 a, the coating 40 can have a uniform thickness without post-treatments, such as grinding or polishing, thereby decreasing manufacturing costs and material waste.

It should be appreciated that, although the heat exchanger 14 is described as a heat exchanger to cool compressed air exiting the turbocharger 12, the present disclosure contemplates use with any heat exchanger used for various applications and with various coolants. Further, the present disclosure contemplates use with fluid-handling apparatuses, other than heat exchangers, that are subjected to high velocity fluid flow.

It should further be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present invention in any way. Thus, those skilled in the art will appreciate that other aspects, objects, and advantages of the invention can be obtained from a study of the drawings, the disclosure and the appended claims.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7992628 *May 9, 2006Aug 9, 2011Modine Manufacturing CompanyMulti-passing liquid cooled charge air cooler with coolant bypass ports for improved flow distribution
US20100319887 *Jun 11, 2010Dec 23, 2010Behr Gmbh & Co. KgHeat-exchanging device and motor vehicle
US20130019819 *Jul 18, 2011Jan 24, 2013Caterpillar Inc.Coolant circuit for engine with bypass line
US20130074814 *Sep 21, 2012Mar 28, 2013Modine Manufacturing CompanyHeat exchanger and method of manufacturing the same
Classifications
U.S. Classification165/133
International ClassificationF28F19/02
Cooperative ClassificationF28F21/085, F28D9/0062, F28F19/06
European ClassificationF28F21/08A6, F28D9/00K, F28F19/06
Legal Events
DateCodeEventDescription
Dec 14, 2004ASAssignment
Owner name: CATERPILLAR, INC., ILLINOIS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ABI-AKAR, HIND;SCOLTON, CHRIS;REEL/FRAME:016088/0380;SIGNING DATES FROM 20041202 TO 20041206