U.S. patent application number 11/393906 was filed with the patent office on 2007-10-04 for heat exchanger tube with a compressed return bend, a serpentine heat exchanger tube with compressed return bends and heat exchanger implementing the same.
Invention is credited to Thomas William III Bugler, Richard Preston Merrill, George Robert Shriver.
Application Number | 20070227713 11/393906 |
Document ID | / |
Family ID | 38557138 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070227713 |
Kind Code |
A1 |
Bugler; Thomas William III ;
et al. |
October 4, 2007 |
Heat exchanger tube with a compressed return bend, a serpentine
heat exchanger tube with compressed return bends and heat exchanger
implementing the same
Abstract
A heat exchanger tube includes a tube body forming a hollow
passageway and having a U-shaped tube section defining a return
bend, a pair of straight tube sections and a pair of transition
sections. Respective ones of the straight tube sections are
connected to the return section with respective ones of the
transition sections disposed therebetween. The straight tube
sections extend generally parallel to one another. Each straight
tube section has a straight tube cross-sectional width and the
return bend has a return bend cross-sectional width that is smaller
than the straight tube cross-sectional width. Multiple heat
exchanger tubes can be connected together to form a serpentine heat
exchanger tube. Multiple serpentine heat exchanger tubes or
multiple heat exchanger tubes can be assembled together to form a
heat exchanger apparatus.
Inventors: |
Bugler; Thomas William III;
(Frederick, MD) ; Shriver; George Robert;
(Sykesville, MD) ; Merrill; Richard Preston;
(Columbia, MD) |
Correspondence
Address: |
RADER FISHMAN & GRAUER PLLC
LION BUILDING
1233 20TH STREET N.W., SUITE 501
WASHINGTON
DC
20036
US
|
Family ID: |
38557138 |
Appl. No.: |
11/393906 |
Filed: |
March 31, 2006 |
Current U.S.
Class: |
165/150 |
Current CPC
Class: |
F28F 1/006 20130101;
F28D 1/0477 20130101 |
Class at
Publication: |
165/150 |
International
Class: |
F28D 1/047 20060101
F28D001/047 |
Claims
1. A tube, comprising: a tube body forming a hollow passageway and
having a U-shaped tube section defining a return bend, a pair of
straight tube sections and a pair of transition sections,
respective ones of the straight tube sections connected to the
return bend with respective ones of the transition sections
disposed therebetween, the straight tube sections extending
generally parallel to one another, each straight tube section
having a straight tube cross-sectional width, the return bend
having a return bend cross-sectional width being smaller than the
straight tube cross-sectional width.
2. A tube according to claim 1, wherein a width ratio of the
straight tube cross-sectional width to the return bend
cross-sectional width is in a range of approximately 1.2 and
1.3.
3. A tube according to claim 1, wherein a width ratio of the
straight tube cross-sectional width to the return bend
cross-sectional width is in a range of approximately 1.1 and
1.6.
4. A tube according to claim 1, wherein the straight tube sections
have a generally uniform straight tube section cross-sectional
configuration.
5. A tube according to claim 4, wherein the straight tube section
cross-sectional configuration is circularly-shaped or
elliptically-shaped.
6. A tube according to claim 1, wherein at least a substantial
entirety of the return bend has a generally uniform return bend
cross-sectional configuration.
7. A tube according to claim 6, wherein the return bend
cross-sectional configuration is generally one of oval-shaped with
opposing parallel sidewalls, oval-shaped, elliptically-shaped and
elliptically-shaped with opposing parallel sidewalls.
8. A tube according to claim 1, wherein each transition section
includes an opposing pair of first walls tapering inwardly from the
straight tube section towards the return bend and an opposing pair
of second walls tapering inwardly from the return bend towards the
straight tube section, individual ones of the opposing pairs of
first and second walls integrally connected in an alternating
manner.
9. A tube according to claim 1, wherein the return bend has a
return bend cross-sectional area and each straight tube section has
a straight tube cross-sectional area being at least substantially
equal to relative to each other and at least substantially equal to
the return bend cross-sectional area.
10. A serpentine tube, comprising: a serpentine tube body disposed
in plane, forming a hollow passageway and having a plurality of
straight tube sections arranged generally parallel with one
another, a plurality of return bends and a plurality of transition
sections, a respective one of the plurality of transition sections
interconnecting respective ones of the plurality of straight tube
sections and the return bends to form a serpentine configuration,
each straight tube section having a generally uniform straight tube
section cross-sectional configuration and a straight tube
cross-sectional width, each return bend having a generally uniform
return bend cross-sectional configuration and a return bend
cross-sectional width being smaller than the straight tube
cross-sectional width.
11. A serpentine tube according to claim 10, wherein a width ratio
of the straight tube cross-sectional width to the return bend
cross-sectional width is in a range of approximately 1.2 and
1.3.
12. A serpentine tube according to claim 10, wherein a width ratio
of the straight tube cross-sectional width to the return bend
cross-sectional width is in a range of approximately 1.1 and
1.6.
13. A heat exchanger apparatus, comprising: an inlet header; an
inlet connection connected to the inlet header; an outlet header;
an outlet connection connected to the outlet header; and a
plurality of adjacent serpentine tube bodies staggered in an
alternating fashion, respective ones of the plurality of adjacent
serpentine tube bodies connected to and between and in fluid
communication with the inlet header and the outlet header, each
serpentine tube body disposed in a selected one of a plurality of
parallel planes in a juxtaposed manner, forming a hollow passageway
and having a plurality of straight tube sections arranged generally
parallel with one another, a plurality of return bends and a
plurality of transition sections, a respective one of the plurality
of transition sections interconnecting respective ones the
plurality of straight tube sections and the return bends to form a
serpentine configuration, each straight tube section having a
generally uniform straight tube section cross-sectional
configuration and a straight tube cross-sectional width, each
return bend having a generally uniform return bend cross-sectional
configuration and a return bend cross-sectional width being smaller
than the straight tube cross-sectional width, staggered juxtaposed
ones of the return bends contacting one another at a location where
the staggered juxtaposed ones of the return bends cross one
another.
14. A heat exchanger according to claim 13, wherein a width ratio
of the straight tube cross-sectional width to the return bend
cross-sectional width is in a range of approximately 1.2 and
1.3.
15. A heat exchanger according to claim 13, wherein a width ratio
of the straight tube cross-sectional width to the return bend
cross-sectional width is in a range of approximately 1.1 and 1.6.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to heat exchanger tubes. More
particularly, the present invention is directed to a heat exchanger
tube with a compressed return bend, a serpentine heat exchanger
tube with compressed return bends and a heat exchanger fabricated
from heat exchanger tubes with compressed return bends.
BACKGROUND OF THE INVENTION
[0002] In the past, manufacturers in the heat exchanger industry
have been known to densely pack heat exchanger tubes in heat
exchangers in order to achieve greater heat exchange efficiency
while simultaneously maintaining or reducing the size of the heat
exchanger. For example, in FIGS. 1-3B, depressions 100 in a form of
indentations, hollows, grooves, notches or dimples are formed in
designated depression areas DA in the return bends 102a of the heat
exchanger tubes 102. This particular densely-packed heat exchanger
tube arrangement is more specifically described in U.S. Pat. No.
6,820,685.
[0003] In FIGS. 3A and 3B, four heat exchanger tubes 102 constitute
a portion of a heat exchanger. These four heat exchanger tubes 102
are stacked in a staggered planar arrangement and the adjacent
return bends 102a overlap one another by an amount of overlap OL
shown in FIG. 3B. As best shown in FIG. 3B and with reference to
FIG. 2, a cross-sectional circular part of one return bend 102a
nests in the depression 100 of the adjacent return bend 102a to
achieve the overlapping effect. By virtue of this overlapping
effect, a heat exchanger assembled with heat exchanger tubes 102
having return bends 102a with depressions 100 formed thereinto can
be considered a densely packed heat exchanger.
[0004] However, there are drawbacks for a densely packed heat
exchanger that uses return bends with depressions formed therein.
First, as shown in FIG. 2, the depression results in a protuberance
104 that projects into the hollow passageway of the heat exchanger
tube 102. Such protuberances, particularly in consideration of the
numerous heat exchanger tubes that constitute a heat exchanger, can
interfere with the heat exchanger fluid flowing therethrough. At a
minimum, the protuberance 104 partially obstructs the flow of the
heat exchanger fluid through the return bend and, at the apex of
the protuberance 104, the cross-sectional area CSA of the hollow
passage way is significantly reduced as shown in FIG. 2. Precision
is required to accurately form the depressions repeatedly at the
same depression area to numerous heat exchanger tubes. Also,
precision in assembly is required in order to properly arrange the
heat exchanger tubes so that the cross-sectional circular parts of
the return bend nests within the depressions. Without the
cross-sectional circular parts nesting properly within the
depressions, a densely packed heat exchanger becomes larger in size
than originally planned.
[0005] It would be beneficial to provide heat exchanger tubes with
return bends that do not include depressions yet can be assembled
to form a densely packed heat exchanger. It would also be
beneficial to provide heat exchanger tubes with return bends that
do not include depressions yet can be assembled to form a densely
packed heat exchanger without consideration of precision assembly.
The present invention provides these benefits.
OBJECTS AND SUMMARY OF THE INVENTION
[0006] It is an object of the invention to provide a heat exchanger
tube with a return bend that does not include any depressions and
can be assembled with similar heat exchanger tubes to form a
densely packed heat exchanger.
[0007] It is another object of the invention to provide heat
exchanger tubes with return bends that do not include any
depressions and can be assembled together to form a densely packed
heat exchanger without any consideration to precisely arranging the
heat exchanger tubes relative to one another.
[0008] It is yet another object of the invention to provide a
densely packed heat exchanger using heat exchanger tubes that, upon
assembly into the densely packed heat exchanger, do not overlap one
another.
[0009] A still further object of the invention is to provide a heat
exchanger tube with a return bend that can be assembled into a
densely packed heat exchanger without significantly reducing the
cross-sectional area of the hollow passageway of the return
bend.
[0010] Accordingly, a heat exchanger tube of the first embodiment
of the present invention, a serpentine heat exchanger tube of the
second embodiment of the present invention and a heat exchanger
apparatus of the third embodiment of the present invention are
hereinafter described.
[0011] The heat exchanger tube of one exemplary embodiment of the
present invention includes a tube body forming a hollow passageway
and having a U-shaped tube section defining a return bend, a pair
of straight tube sections and a pair of transition sections.
Respective ones of the straight tube sections are connected to the
return section with respective ones of the transition sections
disposed therebetween. The straight tube sections extend generally
parallel to one another. Each straight tube section has a straight
tube cross-sectional width and the return bend has a return bend
cross-sectional width that is smaller than the straight tube
cross-sectional width.
[0012] The serpentine heat exchanger tube of another exemplary
embodiment of the present invention includes a serpentine tube body
disposed in plane, forming a hollow passageway and having a
plurality of straight tube sections arranged generally parallel
with one another, a plurality of return bends and a plurality of
transition sections. A respective one of the plurality of
transition sections interconnects respective ones of the plurality
of straight tube sections and the return bends to form a serpentine
configuration. Each straight tube section has a generally uniform
straight tube section cross-sectional configuration and a straight
tube cross-sectional width and each return bend has a generally
uniform return bend cross-sectional configuration and a return bend
cross-sectional width that is smaller than the straight tube
cross-sectional width.
[0013] The heat exchanger apparatus of yet another exemplary
embodiment of the present invention includes an inlet header, an
inlet connection connected to the inlet header, an outlet header,
an outlet connection connected to the outlet header and a plurality
of serpentine tube bodies. Each serpentine tube body is disposed in
a respective plane, forms a hollow passageway and has a plurality
of straight tube sections arranged generally parallel with one
another, a plurality of return bends and a plurality of transition
sections. A respective one of the plurality of transition sections
interconnects respective ones the plurality of straight tube
sections and the return bends to form a serpentine configuration.
Each straight tube section has a generally uniform straight tube
section cross-sectional configuration and a straight tube
cross-sectional width. Each return bend has a generally uniform
return bend cross-sectional configuration and a return bend
cross-sectional width that is smaller than the straight tube
cross-sectional width.
[0014] These objects and other advantages of the present invention
will be better appreciated in view of the detailed description of
the exemplary embodiments of the present invention with reference
to the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a perspective view of a conventional heat
exchanger tube that has depressions formed into its return
bend.
[0016] FIG. 2 is a cross-sectional view along one depression of the
conventional heat exchanger tube in FIG. 1.
[0017] FIG. 3A is a partial perspective view of a conventional heat
exchanger apparatus.
[0018] FIG. 3B is a cross-sectional view of the conventional heat
exchanger apparatus taken along lines 3B-3B-3B in FIG. 3A.
[0019] FIG. 4 is a perspective view of a heat exchanger tube of a
first exemplary embodiment of the present invention.
[0020] FIG. 5 is a side elevational view of the heat exchanger tube
in FIG. 4.
[0021] FIG. 6 is a top planar view of the heat exchanger tube in
FIG. 4.
[0022] FIG. 7 is a front elevational view of the heat exchanger
tube in FIG. 4.
[0023] FIG. 8 is a cross sectional view of the heat exchanger tube
taken along line that 8-8 in FIG. 5.
[0024] FIG. 9 is a cross sectional view of the heat exchanger tube
taken along line that 9-9 in FIG. 5.
[0025] FIG. 10 is a perspective view of a conventional heat
exchanger tube having a continuous circular cross-section.
[0026] FIG. 11 is a cross sectional view of the conventional heat
exchanger tube taken along line 11-11 in FIG. 10.
[0027] FIG. 12 is a cross sectional view of the conventional heat
exchanger tube taken along line 12-12 in FIG. 10.
[0028] FIG. 13 is a perspective view of the conventional heat
exchanger tube in FIG. 10 disposed between a pair of pressing
members.
[0029] FIG. 14 is a front elevational view of the conventional heat
exchanger tube and pressing members shown in FIG. 13 with forces F1
and F2 being applied to the pressing members.
[0030] FIG. 15 is a top planar view of the conventional heat
exchanger tube and pressing members shown in FIG. 13 with forces F1
and F2 being applied to the pressing members.
[0031] FIG. 16 is a top planar view of the heat exchanger tube of
the first embodiment of the present invention as shown in FIG. 4
after its return bend has been compressed by the forces F1 and
F2.
[0032] FIG. 17 is an alternative cross sectional configuration in a
form of an oval with a pair of opposing flat side walls of either
the return bend or the straight tube sections of the heat exchanger
tube of the first embodiment of the present invention.
[0033] FIG. 18 is an alternative cross sectional configuration in a
form of an oval of either the return bend or the straight tube
sections of the heat exchanger tube of the first embodiment of the
present invention.
[0034] FIG. 19 is an alternative cross sectional configuration in a
form of an ellipse of either the return bend or the straight tube
sections of the heat exchanger tube of the first embodiment of the
present invention.
[0035] FIG. 20 is a perspective view of a serpentine tube of a
second embodiment of the present invention.
[0036] FIG. 21 is a perspective view of a heat exchanger apparatus
of a third embodiment of the present invention.
[0037] FIG. 22 is a partial perspective view of the heat exchanger
apparatus in FIG. 21.
[0038] FIG. 23 is a cross-sectional view of the heat exchanger
apparatus taken along lines 23-23 in FIG. 22.
[0039] FIG. 24 is a cross-sectional view of the heat exchanger
apparatus taken along lines 24-24 in FIG. 22 perspective view of a
heat exchanger tube of a first exemplary embodiment of the present
invention.
[0040] FIG. 25 is a side elevational view of two crossing,
staggered, juxtaposed return bends of the heat exchanger tube in
FIG. 21 contacting one another at location X.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0041] Hereinafter, embodiments of the present invention will be
described with reference to the attached drawings. The structural
components common to those of the prior art and the structural
components common to respective embodiments of the present
invention will be represented by the same symbols and repeated
description thereof will be omitted.
[0042] A first exemplary embodiment of a heat exchanger tube 10 of
the present invention is hereinafter described with reference to
FIGS. 4-9. As best shown in FIGS. 4-7, the heat exchanger tube 10,
hereinafter referred to as tube 10, of the present invention
includes a tube body 12. One of ordinary skill in the art would
appreciate that the tube 10 might be used in other applications
other than in heat exchanger apparatuses. The tube body 12 forms a
hollow passageway 14 and has a U-shaped tube section defining a
return bend 16, a pair of straight tube sections 18 and a pair of
transition sections 20. Respective ones of the straight tube
sections 18 are connected to the return bend 16 section with
respective ones of the transition sections 20 disposed
therebetween. The straight tube sections 18 extend generally
parallel to one another at shown in FIG. 5. The term "generally
parallel" means that the opposing straight tube sections 18, 18,
relative to the return bend 16, might perfectly parallel one
another, might taper slightly towards each other or might diverge
slightly away from each other as is commonly known in the heat
exchanger industry.
[0043] As shown in FIG. 8, each straight tube section 18 has a
straight tube cross-sectional width Wsts and, at shown in FIG. 9,
the return bend 16 has a return bend cross-sectional width Wrb. The
return bend cross-sectional width Wrb is smaller than the straight
tube cross-sectional width Wsts. Preferably, a width ratio of the
straight tube cross-sectional width Wsts to the return bend
cross-sectional width Wrb is in a range of approximately 1.2 and
1.3. However, it is theorized by the inventors that the width ratio
of the straight tube cross-sectional width Wsts to the return bend
cross-sectional width Wrb might be in a range of approximately 1.1
and 1.6. With reference to FIG. 8, each straight tube section has a
straight tube cross-sectional height Hsts and, with reference to
FIG. 9, the return bend has a return bend cross-sectional height
Hrb. The return bend cross-sectional height Hrb, as reflected in
FIG. 9, is larger than the straight tube cross-sectional height
Hsts. However, one of ordinary skill in the art would appreciate
that there are conventional tube bending techniques capable of
controlling the return bend cross-sectional height Hrb. Therefore,
it is possible that the return bend cross-sectional height Hrb
might be equal to or even smaller than the straight tube
cross-sectional height Hsts.
[0044] As shown in FIGS. 4-8, the straight tube sections 18, 18
have a generally uniform straight tube section cross-sectional
configuration. As the shown in FIGS. 4, 7 and 8, the straight tube
section cross-sectional configuration is circularly-shaped. As
shown in FIGS. 4-7 and 9, the return bend 16 is a generally uniform
in its return bend cross-sectional configuration at least
substantially along its entirety and is absent of any depressions.
For this embodiment, the return bend cross-sectional configuration
is generally elliptically-shaped as best shown in FIG. 9. Note that
the return bend 16 includes opposing parallel sidewalls 22.
[0045] In FIG. 7, each straight tube section 18 has a straight tube
cross-sectional area CAsts. The straight tube cross-sectional area
CAsts of the straight tube sections 18,18 are at least
substantially equal relative to each other. In FIG. 9, the return
bend 16 has a return bend cross-sectional area CArb. With reference
to FIGS. 8 and 9, the return bend cross-sectional area CArb and the
straight tube cross-sectional area CAsts are at least substantially
equal to each other. By way of example only and not by way of
limitation, it was empirically determined that the return bend
cross-sectional area CArb was approximately 31/2% smaller that the
straight tube cross-sectional area CAst when using a one-inch tube
having a 1.05-inch outer diameter that was formed into a generally
elliptically-shaped cross-sectional return bend having a 11/4-inch
height and a 0.85-inch width.
[0046] By way of example only and not by way of limitation, a
method for fabricating the tube 10 of the present invention is
described with reference to FIGS. 10-16. A tube 10a in FIG. 10 has
a constant circular cross-sectional configuration both along the
straight tube sections 18a, 18a and along the return bend 16a as
shown in FIGS. 11 and 12. In FIGS. 13-15, return bend 16a of the
tube 10a is placed between a pair of pressing members 24. Forces F1
and F2 of approximately equal magnitude are applied to respective
ones on the pressing members 24. The magnitude of the forces F1 and
F2 are sufficient to compress the return bend 16a to form the tube
10 of the present invention described above. Since a circular tube
is merely compressed at its return bend, a skilled artisans would
appreciate that the return bend cross-sectional area CArb and the
straight tube cross-sectional areas CAsts are at least
substantially equal to each other. Also, it would be appreciated
that since a single bent tube is compressed at the return bend 16,
then the straight tube cross-sectional areas CAsts are at least
substantially equal to each other.
[0047] Compressing the return bend 16a to form the tube 10 of the
present invention forms the transition sections 20. As best shown
in FIGS. 5 and 6, each transition section includes an opposing pair
of first walls 26 tapering inwardly from the straight tube section
18 towards the return bend 16 (FIG. 6) and an opposing pair of
second walls 28 tapering inwardly from the return bend 16 towards
the straight tube section 18. Individual ones of the opposing pairs
of first and second walls 26 and 28 respectively are integrally
connected in an alternating manner as shown in FIGS. 5-7.
[0048] A skilled artisan would comprehend that the tube 10 of the
present invention might have other cross-sectional configurations
of the straight tube sections and the return bend. By way of
example only and not by way of limitation, the return bend
cross-sectional configuration and/or the straight tube sections
cross-sectional configurations can be generally oval-shaped as
shown FIG. 17 with opposing parallel sidewalls 22a, oval-shaped as
shown in FIG. 18 or elliptically-shaped as shown in FIG. 19
although other cross-sectional configurations might be used.
[0049] A serpentine tube 210 of a second exemplary embodiment of
the present invention is illustrated in FIG. 20. The serpentine
tube 210 includes a serpentine tube body 212 disposed in plane P
and forms the hollow passageway 14. The serpentine tube body 212
has a plurality of straight tube sections 18 arranged generally
parallel with one another, a plurality of return bends 16 in a
compressed form and a plurality of transition sections 20. A
respective one of the plurality of transition sections 20
interconnects respective ones of the plurality of straight tube
sections 18 and the return bends 16 to form a serpentine
configuration in FIG. 20. Each straight tube section 18 has a
generally uniform straight tube section cross-sectional
configuration and a straight tube cross-sectional width as
discussed above. Each return bend 16 has a generally uniform return
bend cross-sectional configuration and a return bend
cross-sectional width as discussed above. The return bend
cross-sectional width is smaller than the straight tube
cross-sectional width as discussed above. Also, as discussed above,
each straight tube section 18 has a straight tube cross-sectional
height and each return bend 16 has a return bend cross-sectional
height that is larger than the straight tube cross-sectional
height.
[0050] A heat exchanger apparatus 310 of a third exemplary
embodiment of the present invention is illustrated in FIGS. 21-25.
In FIG. 21, the heat exchanger apparatus 310 includes an inlet
header 312, an inlet connection 314 connected to the inlet header
312, an outlet header 316, an outlet connection 318 connected to
the outlet header 316 and a plurality of adjacent serpentine tube
bodies 212, the details of which being discussed above. Respective
ones of the plurality of adjacent serpentine tube bodies 212 are
connected to and between and in fluid communication with the inlet
header 312 and the outlet header 316. As best shown in FIGS. 21-25,
the plurality of adjacent serpentine tube bodies 212 are staggered
in an alternating fashion with each serpentine tube body 212 being
disposed in a selected one of a plurality of parallel planes P1
through Pn (FIG. 21) in a juxtaposed manner. Staggered juxtaposed
ones of the return bends 16 as illustrated in FIGS. 23 and 25
contact one another at a location X in FIG. 25 where the staggered
juxtaposed ones of the return bends 16 cross one another.
[0051] According to the present invention, the heat exchanger tube
includes a compressed return bend without any depressions. A
plurality of such heat exchanger tubes can be assembled to form a
densely packed heat exchanger without consideration to precisely
arranging the heat exchanger tubes relative to one another. Without
depressions, the compressed return bends do not overlap one another
as in the prior art. Further, a heat exchanger tube with a
compressed return bend and without depressions does not
substantially reduce the cross-sectional area of the hollow
passageway of the return bend as does those heat exchanger tubes
with depressions.
[0052] The present invention, may, however, be embodied in various
different forms and should not be construed as limited to the
exemplary embodiments set forth herein; rather, these exemplary
embodiments are provided so that this disclosure will be thorough
and complete and will fully convey the scope of the present
invention to those skilled in the art.
* * * * *