U.S. patent application number 11/011895 was filed with the patent office on 2006-06-15 for fluid-handling apparatus with corrosion-erosion coating and method of making same.
Invention is credited to Hind Abi-Akar, Chris Scolton.
Application Number | 20060124283 11/011895 |
Document ID | / |
Family ID | 36582434 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060124283 |
Kind Code |
A1 |
Abi-Akar; Hind ; et
al. |
June 15, 2006 |
Fluid-handling apparatus with corrosion-erosion coating and method
of making same
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.
Inventors: |
Abi-Akar; Hind; (Peoria,
IL) ; Scolton; Chris; (La Rose, IL) |
Correspondence
Address: |
Michael B. McNeil;Liell & McNeil Attorneys PC
P.O. Box 2417
Bloomington
IN
47402
US
|
Family ID: |
36582434 |
Appl. No.: |
11/011895 |
Filed: |
December 14, 2004 |
Current U.S.
Class: |
165/133 |
Current CPC
Class: |
F28F 19/06 20130101;
F28D 9/0062 20130101; F28F 21/085 20130101 |
Class at
Publication: |
165/133 |
International
Class: |
F28F 19/02 20060101
F28F019/02 |
Claims
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
[0001] 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
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] The present disclosure is directed at overcoming one or more
of the problems set forth above.
SUMMARY OF THE INVENTION
[0007] 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.
[0008] 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.
[0009] 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
[0010] FIG. 1 is a schematic representation of an engine system,
according to the present disclosure;
[0011] FIG. 2 is a sectioned side diagrammatic representation of a
heat exchanger within the engine system of FIG. 1;
[0012] FIG. 3 is an isometric view of a sectioned core of the heat
exchanger of FIG. 2; and
[0013] 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
[0014] 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.
[0015] 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.
[0016] 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 16a, 17a, 20a and a core surface 16b, 17b and 20b,
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 36a of the sea water passages 36 to the middle
manifold 20 in which the sea water changes direction, through a
second portion 36b 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.
[0017] 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 16b,
17b and 20b and the housing surfaces 16a, 17a and 20a of the sea
water manifolds 16, 17 and 20, and surfaces defining the sea water
passages 36. A first portion 43a of the wetted surfaces 43 are
corrosion-erosion prone 43a and a second portion 43b 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 43a 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 43b subject to contact from
less turbulent flow of the sea water. The first portion 43a
includes at least one sea water inlet surface 39. The surfaces 39
include the surfaces 16a, 16b and 20a and 20b 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 17b and the housing surfaces 17a defining the outlet
manifold 17 are also included within the first portion 43a. 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 43b
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 43a 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 43a.
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.
[0018] 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 43b. 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.
[0019] 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 16b, 17b and 20b (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.
[0020] 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 43a
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 43a, illustrated as copper. The coating 40
preferably is sufficiently similar to the surfaces 43a such that
the coating 40 and the corrosion-erosion prone wetted surfaces 43a
are galvanic compatible. Those skilled in the art will appreciate
that the galvanic compatibility of the coating 40 and the surfaces
43a is dependent on various factors, including, but not limited to,
the difference in the galvanic potentials of the coating 40 and the
surfaces 43a, whether the coating 40 or the surface 43a 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 43a. In each
of the example coatings set forth in Table I, the coating 40
includes a metal alloy principally comprised of copper.
[0021] 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 43a 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 43a are subjected. For
instance, in the illustrated heat exchanger, the compressed air is
entering the air passages 34 at approximately 200.degree. C. and
exiting the air passages 34 at approximately 40.degree. C. Because
the air flowing through the air passages 34 transverses the core
surfaces 16b, 17b and 20b, the sea water core surfaces 16b, 17b and
20b are subject to temperature range of 49-200.degree. C. The
coating 40 is principally comprised of the same material as the
surfaces 43a, 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 43a as long as the alloy include a similar
coefficient of thermal expansion as copper.
[0022] 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.
[0023] 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 43a, is galvanic compatible with the surfaces 43a in the
relevant cooling liquid (e.g. sea water) and has a similar
coefficient of thermal expansion as the surfaces 43a, 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 43a from impingement that can lead to corrosion and
erosion. The coating 40 with the nickel is harder than the
corrosion-erosion prone surfaces 43a 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 40a, and the manganese contributes to the
stability of the coating 40a. Moreover, because the coating 40
includes almost 90% copper, the coating 40a is sufficiently similar
to the copper manifold surfaces 16a, 16b, 17a, 17b, 20a and 20b to
which the coating 40a is applied. Thus, the coating 40 is galvanic
compatible with the surfaces 43a, thereby providing a stable
coating 40a even in relatively highly polluted waters, and will not
expand at a sufficiently different rate than the surfaces 43a
despite the heat fluctuations within the heat exchanger 14. Also,
example coating 1 is resistant to biological fowling in polluted
waters.
[0024] 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 43a
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 43a, 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 43a than the preferred coating 40 of Example 1 in highly
polluted waters.
[0025] 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.
[0026] 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 40a-c, example coating 5
preferably includes manganese and iron.
INDUSTRIAL APPLICABILITY
[0027] 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.
[0028] 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 43a are distinguished from the
non-corrosion-erosion prone surfaces 43b, and only the
corrosion-erosion prone surfaces 43a will be coated. Although the
corrosion-erosion prone surfaces 43a may differ between different
types of heat exchangers, the corrosion-erosion prone surfaces 43a
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 43b includes the wetted
surfaces 43 with which the sea water does not directly impinge. The
surfaces 16a, 16b, 20a, 20b, 17a and 17b 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 16a, 17a, 16b
and 17b before being directed into and out of the sea water
passages 36, the housing surface 20a of the middle manifold 20
directs the sea water flow from the first portion 36a to the second
portion 36b 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 16b, 17b
and 20b and the housing surfaces 16a, 17a and 20a, and not applied
to the surfaces of the sea water fins 35 defining the sea water
passages 36.
[0029] 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 43a, being the core surfaces 16b, 17b and 20b and the
housing surfaces 16a, 17a and 20a. Because the core surface 16b,
17b, and 20b 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 16a, 17a and 20a 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 43a. 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 43a,
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 43a. 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 43a must be prepared and
cleaned in a conventional manner when using thermal spray coating
methods.
[0030] 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.
[0031] Once the core 30 is assembled and the core surfaces 16b, 17b
and 20b and the housing surfaces 16a, 17a and 20a 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.
[0032] 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 43a 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 43b, 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.
[0033] 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 43a from
impingement, corrosion and erosion that can lead to holes within
the surfaces 43a, 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.
[0034] 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 43a, the coating 40 is galvanic compatible with the
surfaces 43a. Moreover, even if subjected to extreme temperature
change, the coating 40 will adhere to the surfaces 43a due to the
similar coefficients of thermal expansion between the coating 40
and the surfaces 43a.
[0035] Further, the coating 40 can be applied with relative ease.
Because the corrosion-erosion prone surfaces 43a 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 43a, the coating 40 can have a uniform thickness without
post-treatments, such as grinding or polishing, thereby decreasing
manufacturing costs and material waste.
[0036] 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.
[0037] 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.
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