U.S. patent application number 11/784264 was filed with the patent office on 2007-10-11 for method and apparatus for heat exchanging.
Invention is credited to Jose Mauricio Recio, Brian Zinck.
Application Number | 20070235170 11/784264 |
Document ID | / |
Family ID | 38573915 |
Filed Date | 2007-10-11 |
United States Patent
Application |
20070235170 |
Kind Code |
A1 |
Zinck; Brian ; et
al. |
October 11, 2007 |
Method and apparatus for heat exchanging
Abstract
The subject invention pertains to a method and apparatus for
heating exchanging. In various embodiments, the application of
coating, plating, soldering, and brazing technologies can be used
to create high performance heat exchangers. Specific embodiments of
the subject heat exchanger can be lightweight and resistant or
impervious to oxidation and/or corrosion. Specific embodiments of
the subject heat exchanger can be highly manufacturable.
Embodiments of the subject invention are directed to a heat
exchanger that includes primarily, but not necessarily entirely,
components or assemblies that are made from aluminum and/or
aluminum alloys, and are coated or plated with a more oxidation
and/or corrosion resistant metal. The coated or plated aluminum
components or assemblies can be specifically resistant to corrosion
or oxidation in the presence of water or water based solutions and
mixtures. The metallic coating or plating materials can have
excellent thermal conductivity so as to minimize the reduction of
heat exchanger performance. Furthermore, these coated or plated
components or assemblies can be highly assemblable and
manufacturable as a result of the coating or plating process.
Inventors: |
Zinck; Brian; (Chuluota,
FL) ; Recio; Jose Mauricio; (Oviedo, FL) |
Correspondence
Address: |
SALIWANCHIK LLOYD & SALIWANCHIK;A PROFESSIONAL ASSOCIATION
PO BOX 142950
GAINESVILLE
FL
32614-2950
US
|
Family ID: |
38573915 |
Appl. No.: |
11/784264 |
Filed: |
April 5, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60789765 |
Apr 6, 2006 |
|
|
|
Current U.S.
Class: |
165/133 ;
165/134.1; 165/166; 165/80.4 |
Current CPC
Class: |
F28F 19/06 20130101 |
Class at
Publication: |
165/133 ;
165/134.1; 165/80.4; 165/166 |
International
Class: |
F28F 13/18 20060101
F28F013/18; F28F 19/02 20060101 F28F019/02; F28F 3/00 20060101
F28F003/00 |
Claims
1. An apparatus for exchanging heat, comprising: one or more
components having an aluminum and/or aluminum alloy barrier,
wherein at least a portion of the aluminum and/or aluminum alloy
barrier is coated with a metal coating such that the metal coated
surface is in contact with a first medium during operation of the
apparatus, wherein the metal coated surface is more oxidation
and/or corrosion resistant to the first medium than a surface of
the uncoated aluminum and/or aluminum alloy barrier.
2. The apparatus according to claim 1, wherein at least one of the
one or more components is in thermal contact with a heat source
such that heat is transferred from the heat source to the first
medium through the aluminum and/or aluminum alloy barrier and the
metal coating of the at least one of the one or more
components.
3. The apparatus according to claim 2, wherein the one or more
components form a first channel for the first medium to flow
through, wherein a first interior surface of the first channel is
the metal coated surface of the aluminum and/or aluminum alloy
barriers of at least one of the one or more components.
4. The apparatus according to claim 3, wherein the one or more
components form a second channel for a second medium to flow
through, wherein the second medium is the heat source, wherein heat
is transferred from the second medium to the first medium.
5. The apparatus according to claim 4, wherein a second interior
surface of the second channel is the metal coated surface of the
aluminum and/or aluminum alloy barriers of a second at least one of
the one or more components, wherein the second interior surface is
more oxidation and/or corrosion resistant to the second medium than
the surface of the uncoated aluminum and/or aluminum alloy
barrier.
6. The apparatus according to claim 1, wherein the metal is
selected from the following group: zinc, tin, lead, silver, gold,
copper, cadmium, nickel, and mixtures or alloys thereof.
7. The apparatus according to claim 1, wherein the metal is
copper.
8. The apparatus according to claim 1, wherein the first medium is
a refrigerant.
9. The apparatus according to claim 1, wherein the first medium is
water or a water-based solution.
10. The apparatus according to claim 4, wherein the first medium
and the second medium flow in a counter flow pattern.
11. The apparatus according to claim 4, wherein the first medium
and the second medium flow in a parallel flow pattern.
12. The apparatus according to claim 4, wherein the first medium is
a refrigerant.
13. The apparatus according to claim 8, wherein the apparatus is a
refrigerant condenser.
14. The apparatus according to claim 8, wherein the apparatus is a
refrigerant evaporator.
15. A method for manufacturing a heat exchanger, comprising:
providing one or more components having an aluminum and/or aluminum
alloy barrier, wherein the one or more components form a first
channel for a first medium to flow through; locating a heat source
in thermal contact with the one or more components such that heat
is transferred from the heat source to the first medium through the
aluminum and/or aluminum alloy barrier of at least one of the one
or more components; coating at least a portion of the aluminum
and/or aluminum alloy barrier with a metal coating such that the
metal coated surface is in contact with a first medium, wherein the
metal coated surface is more oxidation and/or corrosion resistant
to the first medium than a surface of the uncoated aluminum and/or
aluminum alloy barrier.
16. The method according to claim 15, wherein coating at least a
portion of the aluminum and/or aluminum alloy barrier comprises:
performing a zincate treatment to the at least a portion of the
aluminum and/or aluminum alloy barrier to form a coat of zinc;
plating the zinc coated at least a portion of the aluminum and/or
aluminum alloy barrier with the metal.
17. The method according to claim 15, wherein coating at least a
portion of the aluminum and/or aluminum alloy barrier further
comprises acid etching the at least a portion of the aluminum
and/or aluminum alloy barrier prior to performing the zincate
treatment.
18. The method according to claim 17, wherein the metal is selected
from the following group: zinc, tin, lead, silver, gold, copper,
cadmium, nickel, and mixtures or alloys thereof.
19. The method according to claim 17, wherein the metal is
copper.
20. The method according to claim 19, further comprising: applying
a layer of nickel before metal plating with copper.
21. The method according to claim 20, wherein the layer of nickel
is between 0.0001 inches and 0.01 inches thick.
22. The method according to claim 16, wherein plating with the
metal comprises electrolytically depositing the metal.
23. The method according to claim 16, wherein the first medium is a
refrigerant.
24. The method according to claim 16, wherein the first medium is
water or a water-based solution.
25. The apparatus according to claim 3, wherein the metal is
copper.
26. The apparatus according to claim 25, wherein the first medium
is water or a water-based solution.
27. An apparatus for exchanging heat, comprising: at least two
components each having an aluminum and/or aluminum alloy surface
that are soldered or brazed to another of the at least two
components, wherein at least a portion of the aluminum and/or alloy
surface of each of the at least two components that is soldered or
brazed to another of the at least two components is coated with a
metal coating, wherein the metal coated surface is more solderable
or brazable respectively, than the aluminum and/or aluminum alloy
surface.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of U.S.
Provisional Application Ser. No. 60/789,765, filed Apr. 6, 2006,
which is hereby incorporated by reference herein in its entirety,
including any figures, tables, or drawings.
FIELD OF THE INVENTION
[0002] The subject invention pertains to a method and apparatus for
heating exchanging. In various embodiments, the application of
coating, plating, soldering, and brazing technologies can be used
to create high performance heat exchangers. Specific embodiments of
the subject heat exchanger can be lightweight and resistant to
oxidation and/or corrosion. Specific embodiments of the subject
heat exchanger can be highly manufacturable.
BACKGROUND OF INVENTION
[0003] Heat exchangers are devices that allow heat to be
transferred from one medium to a second medium without bringing the
two media into direct contact. A physical barrier between the two
media is utilized to prevent contact while allowing heat to
transfer from one media to the other. Heat can be transferred
between the media by the typical means of heat transfer including
conduction, convection, and radiation. The materials, geometry,
design, and construction techniques utilized to make the heat
exchanger can dramatically affect the heat transfer performance.
These factors also determine the weight and corrosion resistance of
the resultant heat exchanger.
[0004] An example of a heat exchanger is the radiator in a typical
car. Hot fluid (typically a water and ethylene glycol mixture) is
pumped through the radiator (heat exchanger) located in the front
of the car. Relatively cool air flows through the radiator to cool
the fluid. Air flow can be generated by either the motion of the
car relative to the ambient air, or driven by fans next to the
radiator. Air never comes into contact with the fluid and visa
versa, with heat being transferred from the hot fluid to the cooler
air.
[0005] The thermal conductivity of the heat exchanger construction
materials is typically very important to heat exchanger
performance. The mechanical strength is also important as the
medium is usually at a pressure higher than exists at atmospheric
conditions. Weight and volume of the heat exchanger are also often
important factors in heat exchanger design. Metals are commonly
utilized to construct heat exchangers due to the desired material
characteristics.
[0006] A wide variety of metals are commonly utilized to design and
manufacture heat exchangers. Steel, stainless steel, copper, and
aluminum are common metals used to make heat exchangers. Other
metals such as titanium are also used for some specialized
applications. Each material offers advantages and disadvantages
depending on the design and manufacturing requirements of the heat
exchanger. Copper and aluminum are often preferred over other
materials for many applications as they offer high thermal
conductivity, relatively low cost, high mechanical strength, and
allow for good manufacturability.
[0007] Heat exchanger weight can be a significant factor when
designing, manufacturing, and/or selecting a heat exchanger. In
fact, in many applications, weight may be considered in the design
process to be the most important factor of all. Some examples where
weight is very important in the design of heat exchangers include
those for military and aerospace applications. The density of the
metals used in the design and construction of a heat exchanger is a
very important physical property to consider. The density of some
of the common metals utilized for heat exchangers is shown in Table
I. The tensile strength of the material is also very important in
the design of heat exchangers. The tensile strength is also shown
for the materials listed in Table I.
TABLE-US-00001 TABLE I Typical Properties of Metals Commonly
Utilized for Heat Exchangers Tensile Strength Density Tensile
Strength, to Density Material (lb/ln3) ultimate (psi) ratio
(psi/lb/ln3) Copper, 0.324 37,700 116,358 UNS C10100 Stainless
steel, 0.289 84,100 291,003 AISI type 316 Steel, AISI 1010 0.284
52,900 186,268 Titanium, 0.163 31,900 195,706 elemental Titanium,
0.162 0.175 35,000 220,000 216,049 1,257,142 various alloys
Aluminum, 0.098 45,000 459,184 6061-T6 Aluminum, 0.102 83,000
813,725 7075-T6
[0008] A relatively high tensile strength allows for the use of
thinner configurations that can handle forces equivalent to the
forces that can be handled by thicker configurations made from
lower tensile strength materials. Thinner configurations allow the
use of less material, thereby enabling the reduction of the weight
of the heat exchanger. The tensile strength to density ratio
becomes an important metric as it combines the relative advantages
and/or disadvantages to a single metric. Therefore, in applications
where weight is a significant factor, a high tensile strength to
density ratio is typically desirable.
[0009] Titanium alloys can have exceptionally high tensile strength
to density ratios, as shown in Table I. However, heat exchangers
made of titanium and/or titanium alloys can be difficult to
fabricate, and can be expensive. Thus titanium and titanium alloy
heat exchangers are commonly only used for specialized
applications.
[0010] Aluminum alloys offer the next best tensile strength to
density ratios compared to the titanium alloys. Aluminum is
relatively inexpensive and numerous lower cost fabrication and
assembly techniques are well documented. Aluminum and aluminum
alloys are relatively easy to machine, shear, braze, weld, cut,
drill, or otherwise fabricate. Accordingly, aluminum and aluminum
alloys are widely utilized as heat exchanger materials where weight
is a significant design factor.
[0011] Other important factors when designing, manufacturing, or
selecting a heat exchanger are metal corrosion and oxidation.
Corrosion or oxidation of any part of the heat exchanger can result
in serious performance degradation or failure. Failures can be
defined as a non-containment of either medium in the heat
exchanger, either toward the outside atmosphere or toward one
another where mixing of the two media could occur. Three examples
of different types of corrosion that can occur include--galvanic,
stress, and cavitation. Heat exchanger performance degradation and
failures can be serious problems in some critical applications.
[0012] Unfortunately, although aluminum offers an excellent tensile
strength to density ratio, it offers modest resistance to oxidation
and corrosion. In fact, an oxide coating is quickly and readily
formed on typical aluminum surfaces. In some applications, the
natural aluminum oxide coating actually acts as a beneficial
barrier to further oxidation. However, in some other applications
this natural aluminum oxide coating inadequately protects the
aluminum surface from nearly continuous oxidation. Numerous
techniques are known to help reduce oxidation and corrosion of
aluminum. Protective coatings can be applied to heat exchanger
surfaces to reduce oxidation and corrosion. These coatings include
various paints, anodizing, chromate coatings, polymeric coatings,
and metal cladding. In the case of galvanic corrosion, a
sacrificial anode can be utilized to reduce corrosion of metal to
be protected. Sacrificial anodes must be regularly inspected and
replaced else the metal to be protected can quickly be subjected to
galvanic corrosion which can lead to failures. Galvanic corrosion
can also be limited by choosing materials of construction that are
near each other in the galvanic series chart. In some applications,
oxidation and corrosion inhibitors can be added to the medium which
is in contact with the heat exchanger, thus effectively reducing
oxidation and corrosion to an acceptable rate or level. These
inhibitors have several potential disadvantages including cost,
increased maintenance, and reduced heat exchanger heat transfer
performance.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 shows a cross section of a portion of an embodiment
of a heat exchanger in accordance with the subject invention.
[0014] FIG. 2 shows a cross section of a portion of a heat
exchanger in accordance with an embodiment of the subject
invention.
[0015] FIG. 3 shows a cross section of a portion of a heat
exchanger with plating or coating on the inside and outside
surfaces, in accordance with an embodiment of the subject
invention.
[0016] FIG. 4 shows a cross section of a portion of a heat
exchanger with plating or coating on the inside surfaces, in
accordance with an embodiment of the subject invention.
[0017] FIG. 5 shows an embodiment of a heat exchanger having a main
body and a cover, in accordance with an embodiment of the subject
invention.
[0018] FIG. 6 shows a cross section of an embodiment of a heat
exchanger in accordance with an embodiment of the subject
invention.
[0019] FIG. 7 shows a perspective cross section of an embodiment of
a heat exchanger in accordance with an embodiment of the subject
invention.
[0020] FIG. 8 shows a perspective cross section of an embodiment of
a heat exchanger in accordance with an embodiment of the subject
invention.
DETAILED DESCRIPTION
[0021] The subject invention pertains to a method and apparatus for
heating exchanging. In various embodiments, the application of
coating, plating, soldering, and brazing technologies can be used
to create high performance heat exchangers. Specific embodiments of
the subject heat exchanger can be lightweight and resistant or
impervious to oxidation and/or corrosion. Specific embodiments of
the subject heat exchanger can be highly manufacturable.
[0022] Embodiments of the subject invention are directed to a heat
exchanger that includes primarily, but not necessarily entirely,
components or assemblies that are made from aluminum and/or
aluminum alloys, and are coated or plated with a more oxidation
and/or corrosion resistant metal. The coated or plated aluminum
components or assemblies can be specifically resistant to corrosion
or oxidation in the presence of water or water based solutions and
mixtures. The metallic coating or plating materials can have
excellent thermal conductivity so as to minimize the reduction of
heat exchanger performance. Furthermore, these coated or plated
components or assemblies can be highly assemblable and
manufacturable as a result of the coating or plating process.
[0023] Many processes for plating or coating over aluminum are well
known in the art. Materials for plating or coating aluminum
include, but are not limited to, the following: zinc, tin, lead,
silver, gold, copper, cadmium, and nickel. Mixtures or alloys of
these materials can also be utilized. The plating or coating
processes can be, for example, electro-less or electrolytic. A
single or multiple plating/coating process can be used to create
the final plating or coating. Pre-processing and post-processing
procedures utilized before and/or after the plating or coating
process are well known in the art and can be utilized in accordance
with the subject invention.
[0024] The plating or coating over the aluminum used in the heat
exchanger can be applied to individual components of the heat
exchanger prior to assembly, or the heat exchanger can be partially
or completely assembled first. The plating or coating can be
applied to the inside surfaces and/or_the outside surfaces of the
heat exchanger components or assembly.
[0025] Many of the plating or coating materials are highly
solderable and brazable, thus allowing heat exchangers that are
made in accordance with specific embodiments of the subject
invention to be easily and highly manufacturable. According to the
American Welding Society (AWS), soldering is "a group of joining
processes that produce coalescence of materials by heating them to
the soldering temperature and by using a filler metal (solder)
having a liquidus not exceeding 840.degree. F. (450.degree. C.),
and below the solidus of the base metals". Also, according to the
AWS, "brazing joins materials by heating them in the presence of a
filler metal having a liquidus above 840.degree. F. (450.degree.
C.) but below the solidus of the base metal". Many soldering and
brazing filler materials, as well as the processes utilized to
successfully solder and braze materials, are well documented and
known in the art, and can be incorporated with various embodiments
of the subject invention. Tin/silver soldering alloys have been
found to work very well for joining plated or coated aluminum
surfaces. Excellent solderability and brazability can allow for
relatively simple and cost effective manufacturing of heat
exchangers made in accordance with various embodiments of the
subject invention.
[0026] In an embodiment, aluminum alloys, which exhibit high
tensile strength, can be utilized as a construction material for a
heat exchanger. As less material can be used to design heat
exchangers with specific force and pressure requirements,
embodiments utilizing aluminum can be preferable. Less material
translates to lighter weight heat exchangers, which is very
desirable for some applications. Aluminum type 6061-T6 can be
utilized as a heat exchanger construction material in the subject
invention. In additional embodiments, aluminum types 5052, 7005,
7075, 7175, 7178, and 7475 can be utilized as a construction
material.
[0027] The plating or coating process for aluminum can involve
numerous processes and steps. In an embodiment, the process
involves the following steps: [0028] 1. Degreasing, to eliminate
oils, greases, and dirt from the manufacturing processes used.
[0029] 2. Acid etching, to remove the aluminum oxide film, so as to
improve adhesion of coating or plating materials. [0030] 3. Zincate
treatment, to remove any small amounts of aluminum oxide remaining
from the acid etching, and to coat the aluminum surface with zinc
to prevent the formation of additional aluminum oxide. [0031] 4.
Metal plating.
[0032] In an embodiment of the subject invention, the aluminum
plating process can be modified to optimize plating adhesion,
aluminum coverage, and enhanced endurance. Adhesion, coverage, and
endurance are very important in certain applications, as breaches
in the coating can result in a detrimental failure of the heat
exchanger. Breaches in coating can be caused by a variety of
reasons. As an example, the media in heat exchangers can flow with
a significant velocity, which has the potential to harmfully erode
coating or plating materials. Furthermore, the media in heat
exchangers may contain particulate or contaminants that can abrade
coated or plated surfaces, thus exposing the aluminum barrier
material.
[0033] In embodiments of the subject invention, aluminum components
are processed in the zincate treatment twice, to ensure the
surfaces are free of all aluminum oxide and completely coated with
zinc. Then, in specific embodiments, instead of proceeding directly
to plating with the final desired metallic coating or plating, a
layer of nickel is applied. This layer of nickel can be applied,
utilizing, for example, an electroless process. In many cases, the
layer of zinc is removed and replaced by the metal in the plating
process. The layer of nickel can be between 0.0001'' and 0.010''
thick, but is commonly between 0.0005'' to 0.0015'' thick. The
electroless nickel plating process provides a uniform and complete
coating of nickel over even complex and small passageways and
channels, as are very common in heat exchangers. After the layer of
electroless nickel has been applied, other coating or plating
materials can be applied.
[0034] Embodiments of the invention involve a refrigerant
evaporator or condenser, which are specific types of heat
exchangers. As used herein, a refrigerant is loosely defined as a
substance that can provide a cooling effect. Any refrigerant can be
used, including; but not necessarily limited to, nitrogen, helium,
oxygen, water, air, carbon dioxide, ammonia, R-134a, R-410a, R-600,
R-600a, R-407c R-22, R-404a, R507, R-12, perfluoropolyethers,
perfluorocarbons, and hydrofluoroethers.
[0035] In a refrigerant evaporator, refrigerant is one of the two
media used, and is considered the primary medium. The refrigerant
evaporates, thus changing from a liquid state to a vapor state,
thereby absorbing heat from the secondary medium in the heat
exchanger. Any secondary medium can be used, including, but not
necessarily limited to, another refrigerant, air, water, ethylene
glycol, propylene glycol, oil, or alcohol.
[0036] In a refrigerant condenser, refrigerant is one of the two
media used, and is considered the primary medium. The refrigerant
condenses, thus changing from a vapor state to a liquid state,
thereby giving heat to the secondary medium in the heat exchanger.
Any secondary medium can be used, including, but not necessarily
limited to, another refrigerant, air, water, ethylene glycol,
propylene glycol, oil, or alcohol.
[0037] Embodiments of the invention are directed to a specialized
refrigerant evaporator, which can be used to cool heat generating
components directly without the use of a secondary medium.
[0038] FIG. 1 shows a cross section of an embodiment of a heat
exchanger that can be used to directly cool heat generating
objects. Refrigerant 100 enters the portion of a heat exchanger
shown, removes heat 104 from the heat generating part 103, and
exits 105 the portion of the heat exchanger shown. Refrigerant 100,
105 is used to cool the barrier 102 between it and the heat
generating part 103. Heat transfers 104 from the heat generating
part 103 to the refrigerant 100, 105. The heat generating component
103 can be, for example, a computer processor, a laser diode,
solid-state laser system, resistor, electronic device or other heat
generating device. In an embodiment, the barrier material 102 can
be aluminum. The barrier material 102 can be plated or coated 101
to prevent or inhibit corrosion or oxidation on the inside surface.
FIG. 2 shows a cross section of a portion of a simple heat
exchanger with the plating or coating on the outside 109. Heat is
transferred 112 from the secondary medium 110, 107 to the primary
medium 106, 111. The barrier material 108 can be aluminum. This
heat exchanger can have the plating or coating on the outside, so
as to allow for assembly by soldering or brazing, and to provide
corrosion and oxidation protection to the outside atmosphere.
[0039] FIG. 3 shows a simple heat exchanger with plating or coating
on the inside and outside surfaces 113. Heat is transferred 120
from the secondary medium 118, 115 to the primary medium 114, 119.
The barrier material 117 can be aluminum. This heat exchanger can
have the plating or coating on the inside and outside surfaces 113.
Having the plating or coating on the outside surface can allow for
assembly of multiple sections by soldering or brazing and, provide
corrosion protection from the outside atmosphere, having the
plating or coating on the inside surfaces can provide corrosion
protection from to the inside against corrosion or oxidation
induced by the medium.
[0040] FIG. 4 shows a simple heat exchanger with plating or coating
on the inside 124. Heat is transferred 127 from the secondary
medium 125, 122 to the primary medium 121, 126. The barrier
material 123 can be aluminum. This heat exchanger can have the
plating or coating on the inside surfaces 124, which can provide
corrosion protection against corrosion or oxidation induced by the
medium.
[0041] In a specific embodiment, after nickel is applied to the
surface of the aluminum, copper is plated on top of the electroless
nickel layer on the aluminum. Copper is both corrosion resistant
and highly solderable and brazable. Copper plating is an
electrolytic process so the coating thickness is highly dependent
on the geometry of the parts to be coated and dependent on the
process, the technique, and the equipment used to apply the
coating. In an embodiment, the copper thickness can be between
0.0001'' and 0.010''. In a further embodiment, the copper thickness
is between 0.0005'' to 0.0015'' thick.
[0042] In an embodiment, the heat exchanger is used as an
evaporator and the primary medium is a refrigerant. In a specific
embodiment, the primary medium in the heat exchanger is R-134a and
the secondary medium is water, or a water based solution or
mixture. Without protection, the aluminum surfaces in contact with
the water, or water based solution or mixture, would readily and
nearly continuously oxidize. In addition, the unprotected aluminum
surfaces would be more susceptible to galvanic, stress, and
cavitation corrosion. Such oxidation and corrosion would likely
reduce the heat transfer performance substantially and likely
reduce the usable life of the heat exchanger as a reduction in
barrier material wall thickness occurs. Plating or coating
portions, or all, of the aluminum surfaces exposed to the water, or
water based solution or mixture, reduces or eliminates such
oxidation and/or corrosion. Plating or coating the portions, or
all, of the aluminum surfaces in contact with the water base medium
also helps maintain the quality of the water based medium, by
reducing or eliminating, aluminum and aluminum oxide from entering
the water and deteriorating the quality of the water. Aluminum and
aluminum oxide are undesirable additions to the water, especially
if the water would be used for human consumption (i.e. drinking
water). The Maximum Contaminant Level (MCL) of aluminum in drinking
water is regulated by NSF International, a company that provides
standards for public drinking water quality.
[0043] Other secondary fluids can also be used where the subject
invention provides corrosion and oxidation protection. These
secondary fluids include solutions of water and ethylene glycol
(0.1 to 55.0% by volume), water and propylene glycol (0.1 to 55.0%
by volume). A wide variety of commercially available "inhibited"
glycols can also be utilized in addition to, or in place of, pure
ethylene and propylene glycols. The inhibited glycols contain
beneficial additives, which can minimize the formation of foam
and/or bubbles in the fluid, as well as potentially further reduce
corrosion of metal surfaces.
[0044] In an embodiment, referring to FIG. 5, the subject heat
exchanger is made from two individual components, a main body 129
and a cover 128. In a further specific embodiment, both a main body
and the cover are made from type 6061-T6 aluminum. Both the main
body and cover can be plated or coated in accordance with an
embodiment of the subject invention. In a specific embodiment, the
double zincate treatment, electroless nickel plating of 0.0005'' to
0.0015'' thickness, and copper plating of 0.0005'' to 0.0015''
thickness, can be applied. After the plating processes are complete
for both the body and cover, the two can be attached. In an
embodiment, the body and the cover can be soldered together. In a
specific embodiment, the solder has 93-98% tin and 2-7% silver.
Soldering or brazing is preferred, but not necessary, as
refrigerants can be elusive, where elusive means that the
refrigerants tend to leak, or escape, to some degree, through a
wide variety of o-rings, gaskets, seals, and joints. Soldering or
brazing is preferred as it can create a "hermetic", or perfect,
seal, between the two media and/or with respect to the outside
atmosphere. A cross section of an embodiment of a heat exchanger is
shown in FIG. 6. In this specific embodiment, the narrow channels
130 for one of the media are 0.050'' wide by 0.354'' tall. The
primary medium enters the heat exchanger through a 1/4 inch nominal
hole 132, then enters numerous small diameter holes 131, and then
enters the narrow channel 130.
[0045] FIG. 7 shows a perspective view of the cross section of the
secondary medium inlet region. The secondary medium 134 enters
through the 1/4 inch nominal hole 133, then enters a larger
perpendicular cutout 135, and then enters the narrow channel 136.
The secondary medium flows in the spiral shaped narrow channel as
the spiral shaped narrow channel spiral around, until the secondary
medium reaches numerous small holes near the outlet port.
[0046] As shown in FIG. 8, the secondary medium 138 flows from the
narrow channel 136 through numerous small diameter holes 137 that
are perpendicular to the channel. From the small diameter holes
137, the secondary medium flows to the 1/4 inch diameter nominal
outlet port 139. The primary medium flows through a passage that is
shaped identically to the passage for the secondary medium. In this
embodiment, the two media flow in a counter flow pattern to
optimize heat transfer between them. In an alternative embodiment,
a parallel flow pattern can be utilized. In this embodiment, the
overall size of the heat exchanger is 2.50 inches wide by 4.22
inches long by 0.75 inches high. Thin wall (0.001 inch to 0.025
inch) fin type material can be inserted into the primary and/or the
secondary to enhance heat transfer. Fin stock of a variety of
materials and geometries can be used, and is widely known in the
art.
[0047] In an alternative embodiment, the main body and cover can be
first joined by common aluminum brazing processes, which are well
known in the art. The aluminum brazing process can, for example,
involve a dip brazing process or a vacuum brazing process. In an
embodiment, the two components shown in FIG. 6, the body 129 and
cover 128, can be joined by an aluminum brazing process prior to
plating, and then processed and plated or coated with one of the
various plating or coating processes in accordance with the subject
invention. In an embodiment, after the aluminum brazing process,
the acid etching, the double zincate treatment, and the electroless
nickel plating process can be applied. The solutions and chemicals
used during the plating process may be pumped through the heat
exchanger to ensure adequate and complete contact and coverage of
the barrier material. Electrolytic plating on outside surfaces can
then be accomplished. Preferably, the internal components are
electrolytically plated prior to the cover being installed.
[0048] In a specific embodiment, a heat exchanger used as an
evaporator may be utilized in a small chiller. A chiller can be
loosely defined as a device that cools fluids. The subject chiller
can be used to cool fluids, including those previously mentioned as
secondary media. In this embodiment, the primary medium in the
evaporator can be a refrigerant, such as R-134a. The evaporator can
be manufactured and then processed in accordance with one or more
of the processing techniques described in the subject application.
In this embodiment, the cooled secondary medium can be used to cool
a person or people. In a specific embodiment, commercially
available heat transfer garments can be incorporated with the
chiller to cool one or more people. This "personal cooling" device
is preferably compact and lightweight, with the subject invention
allowing for substantial weight savings. The weight savings for the
evaporator shown in FIG. 6 is shown in Table II.
TABLE-US-00002 TABLE II Evaporator Weight Comparison Plated
aluminum versus copper Copper (lbs) Plated Aluminum (lbs)
Evaporator 0.75 0.23 Cover 0.1 0.03 Total 0.85 0.26 Savings, when
Plated aluminum is used Weight (lbs) 0.59 Percentage 69%
[0049] The weight savings of 0.59 lbs is substantial for a small
chiller product, in which the entire system can typically weigh
between 1.0 and 25.0 lbs. Note that a competitive, commercially
available evaporator sized for this application, and made from
stainless steel and copper, would weigh at least 2.5 lbs. In an
embodiment, an evaporator for use in a small chiller, and made
according to the processes described in the subject application
weighs about 0.26 lbs. The heat transfer rate between the primary
and secondary media, or what is typically characterized as the
device "cooling capacity", can range between 50 and 1000 Watts. The
secondary medium outlet temperature can range between 40 degrees
Fahrenheit to 90 degrees Fahrenheit, and preferably range between
65 degrees Fahrenheit to 75 degrees Fahrenheit. In an embodiment,
the shape of the chiller can be cylindrical, as previously
described by U.S. Pat. No. 7,010,936 B2 (Rini Technologies, Inc.,
Mar. 14, 2006), which is hereby incorporated by reference in its
entirety, or the chiller can have, for example, a square or
rectangular box shape.
[0050] All patents, patent applications, provisional applications,
and publications referred to or cited herein are incorporated by
reference in their entirety, including all figures and tables, to
the extent they are not inconsistent with the explicit teachings of
this specification.
[0051] It should be understood that the examples and embodiments
described herein are for illustrative purposes only and that
various modifications or changes in light thereof will be suggested
to persons skilled in the art and are to be included within the
spirit and purview of this application.
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