U.S. patent application number 12/922389 was filed with the patent office on 2011-02-24 for heat exchanger drip tube.
This patent application is currently assigned to CARRIER CORPORATION. Invention is credited to Andrew E. Karl, Ron A. Wilson.
Application Number | 20110042047 12/922389 |
Document ID | / |
Family ID | 41319335 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110042047 |
Kind Code |
A1 |
Karl; Andrew E. ; et
al. |
February 24, 2011 |
HEAT EXCHANGER DRIP TUBE
Abstract
A drip tube has a generally horizontal section, a generally
vertical section and a drip loop connecting the sections. The drip
loop is positioned so that its exterior surface is lower than the
exterior surfaces of the generally horizontal section and the
generally vertical section at the points where they meet the drip
loop to provide a location where water may drip.
Inventors: |
Karl; Andrew E.; (Greenwood,
IN) ; Wilson; Ron A.; (Greenwood, IN) |
Correspondence
Address: |
Cantor Colburn LLP - Carrier
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
CARRIER CORPORATION
Farmington
CT
|
Family ID: |
41319335 |
Appl. No.: |
12/922389 |
Filed: |
May 14, 2009 |
PCT Filed: |
May 14, 2009 |
PCT NO: |
PCT/US09/43953 |
371 Date: |
September 13, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61127513 |
May 14, 2008 |
|
|
|
Current U.S.
Class: |
165/115 ;
165/158; 29/890.03 |
Current CPC
Class: |
F28F 17/005 20130101;
F28F 9/0246 20130101; Y10T 29/4935 20150115 |
Class at
Publication: |
165/115 ;
165/158; 29/890.03 |
International
Class: |
F28D 5/02 20060101
F28D005/02; F28F 9/02 20060101 F28F009/02; B21D 53/02 20060101
B21D053/02 |
Claims
1. A system comprising: a heat exchanger manifold; and a drip tube
in fluid communication with the heat exchanger manifold, the drip
tube comprising: a generally horizontal section having an exterior
surface; a generally vertical section having an exterior surface;
and a drip loop having an exterior surface and connecting the
horizontal section and the vertical section, wherein a lowest
portion of the drip loop exterior surface is positioned lower than
the horizontal section exterior surface where the horizontal
section and drip loop meet and lower than the vertical section
exterior surface where the vertical section and drip loop meet.
2. The system of claim 1, wherein the heat exchanger manifold and
the drip tube are similar metals.
3. The system of claim 1, wherein the heat exchanger manifold and
the drip tube are dissimilar metals.
4. The system of claim 3, wherein the heat exchanger manifold is
aluminum and the drip tube is copper.
5. The system of claim 1, wherein the drip tube is an inlet or an
outlet for the heat exchanger manifold.
6. The system of claim 1, wherein the horizontal section is
generally perpendicular to the heat exchanger manifold.
7. The system of claim 1, wherein the horizontal section is
connected to the heat exchanger manifold.
8. The system of claim 1 further comprising a belled section,
wherein the belled section connects the heat exchanger manifold and
the drip tube.
9. The system of claim 1 further comprising a barrier layer,
wherein the barrier layer surrounds a portion of the heat exchanger
manifold and a portion of the drip tube.
10. The system of claim 8, further comprising a barrier layer,
wherein the barrier layer surrounds a portion of the belled section
and a portion of the drip tube.
11. A heat exchanger section comprising: first and second
manifolds; a plurality of flow paths extending between the first
and second manifolds; and at least one drip tube in fluid
communication with at least one manifold, the drip tube comprising:
a generally horizontal section having an exterior surface; a
generally vertical section having an exterior surface; and a drip
loop having an exterior surface and connecting the horizontal
section and the vertical section, wherein a lowest portion of the
drip loop exterior surface is positioned lower than the horizontal
section exterior surface where the horizontal section and drip loop
meet and lower than the vertical section exterior surface where the
vertical section and drip loop meet.
12. The heat exchanger section of claim 11, wherein the at least
one drip tube and the at least one manifold in fluid communication
with the at least one drip tube are dissimilar metals.
13. The heat exchanger section of claim 12, wherein the at least
one drip tube is copper and the at least one manifold in fluid
communication with the at least one drip tube is aluminum.
14. The heat exchanger section of claim 11, wherein the at least
one drip tube is an inlet or an outlet for the at least one
manifold in fluid communication with the at least one drip
tube.
15. The heat exchanger section of claim 11, wherein the horizontal
section is connected to the at least one manifold in fluid
communication with the at least one drip tube.
16. The heat exchanger section of claim 11 further comprising a
belled section, wherein the belled section connects the at least
one drip tube and the at least one manifold in fluid communication
with the at least one drip tube.
17. The heat exchanger section of claim 11 further comprising a
barrier layer, wherein the barrier layer surrounds a portion of the
at least one drip tube and a portion of the at least one manifold
in fluid communication with the at least one drip tube.
18. The heat exchanger section of claim 11 further comprising a
barrier layer, wherein the barrier layer surrounds a portion of the
belled section and a portion of the at least one drip tube.
19. A method for protecting aluminum surfaces of a heat exchanger,
the method comprising: shaping a drip tube comprising a generally
horizontal section, a generally vertical section, and a drip loop
connecting the horizontal and vertical sections, wherein the drip
tube is shaped so that an exterior surface of the drip loop is
positioned lower than an exterior surface of the horizontal section
where the horizontal section and drip loop meet and lower than an
exterior surface of the vertical section where the vertical section
and drip loop meet; connecting the horizontal section of the drip
tube to a heat exchanger manifold; and connecting the vertical
section of the drip tube to a refrigerant line.
20. The method of claim 19 further comprising providing a barrier
layer to a portion of the drip tube and a portion of the heat
exchanger manifold.
21. The method of claim 19, wherein the step of connecting the
horizontal section of the drip tube to a heat exchanger manifold
further comprises: connecting a first end of a belled section to
the heat exchanger manifold; and connecting the horizontal section
of the drip tube to a second end of the belled section.
22. The method of claim 21 further comprising providing a barrier
layer to a portion of the drip tube and a portion of the belled
section.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from U.S. Provisional
Application No. 61/127,513, filed on May 14, 2008 and entitled
"Heat Exchanger Drip Tube."
BACKGROUND
[0002] Advances in microchannel heat exchanger technology have
demonstrated its advantages over the previously more conventional
round-tube plate-fin type heat exchanger. Some of the benefits
provided by microchannel heat exchangers include a reduction in the
amount of refrigerant required for operation, more efficient heat
transfer, and a reduced footprint. Microchannel heat exchangers,
once used primarily in automotive applications, are now also
finding use in residential and commercial air conditioning and
refrigeration applications. Microchannel heat exchangers generally
use all aluminum coils. In many applications, however, refrigerant
enters and leaves the coils via copper tubes. A heat exchange
system with aluminum and copper surfaces may run into problems with
galvanic corrosion.
[0003] Galvanic corrosion occurs when two dissimilar metals make
contact with one another in the presence of an electrolyte thereby
forming a galvanic couple. The more noble metal (higher on the
galvanic series) provides the surface area for the reduction
reaction and the less noble metal (lower on the galvanic series)
corrodes in an oxidation process. The oxidation occurs in the
greatest amount at the interface of the two metals but may also
occur at some distance away from the actual interface. In coastal
regions, the most common electrolyte is salt water in the air. A
fine salt water mist may be blown inland for up to fifty miles from
the coast. Sulfur dioxide from industrial pollution also creates an
electrolyte when it combines with moisture in the air.
[0004] If the two dissimilar metals in a heat exchanger are
physically separated from one another, no interface exists for
corrosion to occur. However, water containing particles of copper
may come into contact with aluminum surfaces of the heat exchanger
and form a galvanic couple. In some residential and commercial
refrigeration systems, for example, the condenser section(s) of the
heat exchangers used in vapor compression refrigeration are located
outdoors (e.g., outside the residence, on the rooftops of
commercial buildings). These condensers can be exposed to rain,
snow, sleet, and salt. The water or moisture present in the outdoor
environment has the potential to carry copper particles into
contact with aluminum surfaces of the condenser such as the coils
or the manifolds. Galvanic corrosion can occur in the areas where
copper and aluminum make contact.
SUMMARY
[0005] Exemplary embodiments of the invention include a system
having a heat exchanger manifold and a drip tube in fluid
communication with the manifold. The drip tube includes a generally
horizontal section, a generally vertical section, and a drip loop
connecting the horizontal and vertical sections. The horizontal
section, vertical section, and drip loop each have an exterior
surface. A portion of the drip loop exterior surface is positioned
so that it is lower than the exterior surfaces of the horizontal
and vertical sections where the horizontal and vertical sections
meet the drip loop.
[0006] A further embodiment of the present invention includes a
method for protecting aluminum surfaces of a heat exchanger. The
method includes shaping a drip tube having a generally horizontal
section, a generally vertical section, and a drip loop connection
the horizontal and vertical sections. The drip tube is shaped so
that an exterior surface of the drip loop is positioned lower than
the exterior surfaces of the horizontal and vertical sections where
the horizontal and vertical sections meet the drip loop. The method
also includes connecting the horizontal section of the drip tube to
a heat exchanger manifold and connecting the vertical section of
the drip tube to a refrigerant line.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic illustration of a refrigerant vapor
compression system incorporating a heat exchanger with a drip
tube.
[0008] FIG. 2 is a perspective view of part of a heat exchanger
showing a manifold connected to an inlet tube and a drip tube.
[0009] FIG. 3 is a side view of a heat exchanger manifold connected
to a drip tube.
[0010] FIG. 4 is a cross-section view of a heat exchanger manifold
connected to a drip tube via a belled section with a barrier
layer.
DETAILED DESCRIPTION
[0011] Illustrated in FIG. 1, is an example of a refrigerant vapor
compression system 100. The system includes evaporator 102,
compressor 104, condenser 106, and expansion valve 108. Refrigerant
lines connect the components of the system described above. Fans
110 and 112 direct air across the evaporator 102 and condenser 106,
respectively, as part of the heat transfer system. The condenser
106 includes manifold 12, which is connected to inlet tube 16 and
drip tube 18. While FIG. 1 illustrates drip tube 18 connected to
condenser 106, drip tube 18 could also be connected to an
evaporator such as evaporator 102.
[0012] Illustrated in FIG. 2, is part of a heat exchanger section
10 having a manifold 12 and a plurality of microchannel flow paths
14. Heat exchanger section 10 may function as an evaporator or as a
condenser depending on the desired heat transfer application.
Generally, heat exchanger section 10 is located outdoors (e.g.,
outside a residence, on the rooftop of a commercial building), but
heat exchanger section 10 may also be located indoors. Microchannel
flow paths extend from manifold 12 to another manifold (not shown).
Manifold 12 may be either an inlet or outlet manifold. Manifold 12
and microchannel flow paths are generally aluminum.
[0013] Attached to manifold 12 are inlet and outlet tubes. In the
embodiment shown in FIG. 2, inlet tube 16 is connected to manifold
12 near the top of the manifold. Inlet tube 16 also connects with a
refrigerant line (not shown) in the closed heat exchanger circuit.
Drip tube 18 is connected to manifold 12 near the bottom of the
manifold. Drip tube 18 also functions as an outlet tube in the
embodiment illustrated in FIG. 2. While FIG. 2 illustrates inlet
tube 16 at the top of the manifold and outlet drip tube 18 at the
bottom, other embodiments are possible. For example, tube 16 could
function as an outlet and drip tube 18 could function as an inlet.
In either case, the tube functioning as the drip tube will
generally be located lower on the manifold than the other tube
regardless of which is the inlet or outlet. It is also possible for
both tubes (inlet and outlet) connected to the manifold to be drip
tubes.
[0014] Drip tube 18 includes horizontal section 20, drip loop 22,
and vertical section 24. As illustrated in FIG. 2, at least a
portion of horizontal section 20 is generally horizontal and
generally perpendicular to heat exchanger manifold 12 and vertical
section 24. Horizontal section 20 connects directly with manifold
12 or is inserted into a belled section 26, which is connected to
manifold 12, as shown in FIGS. 2-4. At least a portion of vertical
section 24 is generally vertical and perpendicular to at least a
portion of horizontal section 20. Vertical section 24 connects with
a refrigerant line (not shown) in the closed heat exchanger
circuit. Drip loop 22 connects horizontal section 20 and vertical
section 24. Drip tube 18 is generally copper, but other metals such
as aluminum may be used. Drip tube 18 functions as an inlet or an
outlet for manifold 12. Refrigerant travels through the inner
passage of drip tube 18 to or from manifold 12.
[0015] As illustrated by FIG. 3, drip loop 22 is a generally
U-shaped loop located between horizontal section 20 and vertical
section 24. In the embodiment shown in FIG. 3, drip loop 22 slopes
in a slight downward direction from horizontal section 20 to form
one half of the U shape. Drip loop 22 then curves upward towards
vertical section 24 to form the other half of the U shape. Drip
loop 22 includes a bottom exterior surface 28. At least a portion
of the bottom exterior surface 28 is positioned lower than the
exterior surfaces of horizontal section 20 and vertical section 24
where the horizontal section 20 and vertical section 24 join drip
loop 22. In some embodiments it is possible for horizontal section
20 and vertical section 24 to have exterior surfaces lower than
bottom exterior surface 28, but these surfaces cannot be located
where horizontal section 20 and vertical section 24 join with drip
loop 22. The lowest portion of bottom exterior surface 28 provides
a location where water may collect, form a droplet, and drip.
[0016] In one exemplary embodiment of drip tube 18, drip tube 18
has an outer diameter of about 9.5 mm. The wall thickness of drip
tube 18 is about 0.7 mm. Vertical section 24 of drip tube 18 is
about 42 mm in length. The straight sloped portion of drip loop 22
(the portion between horizontal section 20 and the sharp bend in
drip loop 22) is about 19 mm in length. Drip loop 22 slopes
downward from horizontal section 20 at an angle of about 19.degree.
and the U-bend of drip loop 22 traverses an arc of about
109.degree.. The distance between the centerpoint of manifold 12
and the centerpoint of vertical section 24 is about 76 mm.
Horizontal section 20 connects with manifold 12 about 40 mm above
heat exchanger bottom surface 30. The dimensions of other
embodiments of drip tube 18 may vary. For example, the outer
diameter of drip tube 18 may be between about 2.0 mm and about 25.4
mm. Wall thickness may be between about 0.1 mm to about 4 mm. The
angles and lengths of the different portions of drip tube 18 may be
adapted to the particular needs of the heat exchanger manifold and
refrigerant lines. However, all embodiments will be configured so
that the drip loop has an exterior surface lower than the exterior
surfaces of the horizontal and vertical sections where they connect
to the drip loop.
[0017] Water and moisture (from rain, snow, or condensation) that
collect in heat exchanger section 10 may accumulate on exterior
surfaces of refrigerant lines in fluid communication with drip tube
18. Water may travel down the exterior surfaces of the refrigerant
lines towards the heat exchanger manifold 12. As refrigerant lines
are often made of copper, this water may collect particles of
copper as it travels along the exterior surfaces of the refrigerant
lines. In a heat exchanger without a drip tube, the
copper-containing water may travel to the area where the
refrigerant line (inlet/outlet) connects with the aluminum heat
exchanger manifold 12. The copper and aluminum may form a galvanic
couple and galvanic corrosion may occur at or near the area where
both copper and aluminum are present.
[0018] The drip tube 18 prevents copper-containing water from
reaching the manifold 12. Water travels down the exterior surface
of a refrigerant line and vertical section 24 of drip tube 18. The
water then reaches drip loop 22 and continues to the lowest portion
of bottom exterior surface 28. The water will drip from the lowest
portion of bottom exterior surface 28 rather than continue along
drip loop 22 to horizontal surface 20 and eventually to manifold
12. The water would need to travel "uphill" to reach horizontal
surface 20 from drip loop 22. Gravity will cause the water to form
droplets and drip from the lowest portion of bottom exterior
surface 28 before it can reach horizontal surface 20.
[0019] While FIG. 3 illustrates a U-shaped drip loop 22, other
configurations that provide a bottom exterior surface 28 that is
lower than the exterior surfaces of horizontal section 20 and
vertical section 24 where horizontal section 20 and vertical
section 24 join with drip loop 22 are possible. For example, drip
loop 22 may also have a V-shaped section as long as the lowest
point of the V is lower than the exterior surfaces of the
horizontal section 20 and vertical section 24 where horizontal
section 20 and vertical section 24 join with drip loop 22.
[0020] Water drips from bottom exterior surface 28 of drip loop 22
onto heat exchanger bottom surface 30. In exemplary heat exchanger
embodiments, bottom surface 30 directs collected water away from
manifold 12. Bottom surface 30 may be sloped to facilitate
collection of water in areas of heat exchanger section 10 away from
manifold 12 where it is allowed to evaporate or drain out of heat
exchanger section 10.
[0021] One embodiment of a connection between drip tube 18 and
manifold 12 is illustrated in FIG. 4. Belled section 26 is used to
facilitate the connection of manifold 12 and drip tube 18. In some
embodiments, belled section 26 may be omitted and drip tube 18 is
connected directly to manifold 12. Belled section 26 is generally
aluminum, but other metals, such as copper, may also be used. One
end of belled section 26 is positioned within an opening in the
wall 32 of manifold 12. Horizontal section 20 of drip tube 18 is
positioned in the other end of belled section 26. Once connected,
the inner passages of manifold 12 and drip tube 18 are in fluid
communication.
[0022] Manifold 12 and belled section are typically similar metals
in this construction. Belled section 26 and horizontal section 20
of drip tube 18 are typically dissimilar metals. To prevent
galvanic corrosion between belled section 26 and drip tube 18, one
or more barrier layers 34 may be employed. Barrier layer 34 is
positioned around the joining area of belled section 26 and drip
tube 18 to protect the area where dissimilar metals contact one
another from water and oxygen, thereby preventing or reducing the
opportunity for galvanic corrosion. Barrier layer 34 is generally
placed around belled section 26 or drip tube 18 after connection
with manifold 12. Barrier layer 34 may be a shrink wrap that seals
around belled section 26 when heat is applied to the shrink wrap.
Barrier layer 34 may be any material appropriate to protect metals
from water and oxygen, such as rubber, neoprene, nylon, or
latex.
[0023] While the invention has been described with reference to an
exemplary embodiment(s), it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *