U.S. patent application number 14/738281 was filed with the patent office on 2021-06-24 for heat exchange apparatus.
The applicant listed for this patent is Baltimore Aircoil Company, Inc.. Invention is credited to David Andrew Aaron, Kevin Egolf.
Application Number | 20210190440 14/738281 |
Document ID | / |
Family ID | 1000005636436 |
Filed Date | 2021-06-24 |
United States Patent
Application |
20210190440 |
Kind Code |
A9 |
Egolf; Kevin ; et
al. |
June 24, 2021 |
HEAT EXCHANGE APPARATUS
Abstract
An improved heat exchange apparatus is provided with an indirect
evaporative heat exchange section consisting of a series of
serpentine tubes which are kept uniformly spaced in the return bend
section. Providing uniform return bend spacing on the return bend
ends allow for ease of circuit assembly (stacking), ease of coil
pull-down, ease of manufacturing, reduction in production cost,
produces a higher quality hot dip galvanizing process and is a more
robust design that tolerates manufacturing variability issues such
as variable tube circuit length and variable return bend angles.
Uniform return bend spacing also reduces scaling relative to prior
art designs which had wet/dry areas resulting from shadowed tubes
which were non-uniformly spaced, provides for better inspection and
access to the tubes in the return bend area, maintains uniform air
passage around tubes, promotes better tube wetting of the return
bend area and ultimately promotes higher quality and higher
performing heat exchanger coils.
Inventors: |
Egolf; Kevin; (Hampstead,
MD) ; Aaron; David Andrew; (Reisterstown,
MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baltimore Aircoil Company, Inc. |
Jessup |
MD |
US |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20160363388 A1 |
December 15, 2016 |
|
|
Family ID: |
1000005636436 |
Appl. No.: |
14/738281 |
Filed: |
June 12, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62062539 |
Oct 10, 2014 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 1/047 20130101;
F28F 1/006 20130101 |
International
Class: |
F28F 1/00 20060101
F28F001/00; F28D 1/047 20060101 F28D001/047 |
Claims
1. An indirect heat exchanger assembly comprising: an inlet header
and an outlet header, a series of tubes, each tube extending from
the inlet header to the outlet header, wherein each tube is
comprised of a run section and a return bend section, wherein
certain of the return bend sections are formed with a first bend
angle of about 100 degrees followed by a straight section then
followed by a second bend angle of about 80 degrees, and wherein at
least one of the tube return bend sections contacts both an
adjacent tube return bend section and an adjacent tube run section,
and at least one of the tube run sections contacts an adjacent tube
return bend section.
2. The indirect heat exchange assembly of claim 1 wherein the
series of tubes comprises at least two separate levels of
tubes.
3. The indirect heat exchange assembly of claim 1 wherein the
series of tubes comprises at least four separate levels of
tubes.
4. The indirect heat exchange assembly of claim 1 wherein the
series of tubes comprises at least six separate levels of
tubes.
5. The indirect heat exchange assembly of claim 1 wherein the
series of tubes comprises at least eight separate levels of
tubes.
6. The indirect heat exchange assembly of claim 1 wherein said
straight section of said return bend section is at least 2 inches
(5.08 cm) long.
7. The indirect heat exchange assembly of claim 1 wherein said
first bend angle is at least 90 degrees and not greater than or
equal to 110 degrees and said second bend angle is at least 70
degrees but less than or equal to 90 degrees
8. The indirect heat exchange assembly of claim 1 wherein said
first bend angle is at least 90 degrees and not greater than or
equal to 140 degrees and said second bend angle is at least 40
degrees but less than or equal to 90 degrees.
9. The indirect heat exchange assembly of claims 1, claim 7 and
claim 8 wherein and the sum of the first bend angle and second bend
angle is equal to or greater than 180 degrees.
10. An indirect heat exchange assembly comprising: an inlet header
and an outlet header, a first series of tubes, each tube of the
first series extending from the inlet header to the outlet header,
a second series of tubes, each tube of the second series extending
from the inlet header to the outlet header, each tube of the first
series comprising a run section and a return bend section, each
tube of the second series comprising a run section and a return
bend section, wherein certain of the return bend sections of the
first series of tubes are formed with a first bend angle of about
100 degrees and a second bend angle of about 80 degrees, wherein
certain of the return bend sections of the second series of tubes
are formed with a first bend angle of about 100 degrees and a
second bend angle of about 80 degrees, and wherein at least one of
the tube return bend sections of the first series of tubes contacts
an adjacent tube run section of the second series of tubes at one
point of contact, and wherein at least one of the tube return bend
sections of the first series of tubes contacts an adjacent tube
return bend section of the second series of tubes at one point of
contact, and wherein at least one of the tube run sections of the
first series of tubes contacts an adjacent tube return bend section
of the second series of tubes at one point of contact.
11. The indirect heat exchange assembly of claim 10 wherein the
first series of tubes comprises at least one separate tube and the
second series of tubes comprises at least one separate tube.
12. The indirect heat exchange assembly of claim 10 wherein the
first series of tubes comprises at least two separate tubes and the
second series of tubes comprises at least two separate tubes.
13. The indirect heat exchange assembly of claim 10 wherein the
first series of tubes comprises at least three separate tubes and
the second series of tubes comprises at least three separate
tubes.
14. The indirect heat exchange assembly of claim 10 wherein the
first series of tubes comprises at least four separate tubes and
the second series of tubes comprises at least four separate tubes.
Description
RELATED APPLICATIONS
[0001] The application claims the benefit of U.S. provisional
application 62/062,539, filed Oct. 10, 2014, the entirety of which
is hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to an improved
indirect heat exchanger such as a closed circuit fluid cooler,
fluid heater, condenser, evaporator, thermal storage system, air
cooler or air heater. More specifically, the present invention
relates to a tube bundle in which uniform tube spacing is
maintained in the return bend section of the tube bundle which
allows for ease of circuit assembly, ease of coil pull-down, ease
of manufacturing, reduction in production cost, produces a higher
quality hot dip galvanizing process and is a more robust design
that tolerates manufacturing variability issues such as variable
tube circuit length and variable return bend angles. Uniform return
bend spacing also reduces scaling relative to prior art designs
which had wet/dry areas resulting from shadowed tubes caused from
non-uniformly spaced return bend sections. Uniform return bend
spacing also provides for better inspection and access to the tubes
in the return bend area, maintains uniform air passage around
tubes, promotes better tube wetting of the return bend area,
ultimately promoting higher quality heat exchange coils with higher
unit thermal capacity.
[0003] Such indirect heat exchangers may also be used in
conjunction with direct heat exchangers and are usually comprised
of a series of serpentine tube runs with each tube run providing a
circuit of a coil. When prior art designs of the return bend
section of a coil circuit arrangement have two approximate 90
degree bend angles separated by a straight tube run usually greater
than 2 inches, the return bends can float and can stack unevenly
which promotes uneven tube spacing in the return bend area. This
situation can become worse after the tube bundle is hot dip
galvanized. The degree of freedom for the coil circuits to become
non-uniformly spaced at the return end becomes worse as the
distance between the two approximate 90 degree bends becomes
longer.
[0004] Various number of coil geometries including but not limited
to double serpentine coils, quad-coils, hex-coils and octo-coils
are possible in accordance with the present invention. All such
arrangements can benefit from the improved design of the return
bend sections of the coil.
[0005] In double serpentine coil geometry, there is a top and a
bottom tube that are paired coming out of the coil header which are
offset at different levels. There can be any number of sets of
circuits across the header but the double serpentine design feeds
two circuits, a top and a bottom circuit at a time. So for example,
a coil with 44 circuits would have 22 sets of double serpentine
feeds and could have any number of passes back and forth but
typically have passes between 2-20 passes. So for example a coil
with 12 passes between the top and bottom headers would have 11
return bends. At each return bend end of the coil, when using one
bend of approximately 180 degrees, these circuits cross at one
intersection point and these are generally not a problem due to
their close proximity. However, when the tube runs are separated by
a distance, meaning there would be two approximate 90 degree bends
separated by a straight tube run, there can be one intersection
point between the top and bottom circuit and it is desired that the
return bend section touches for the entire length of the section of
tube in between the two 90 degree bends such that uniform spacing
is maintained at the return bend section on both sides of the coil.
In practice however, when the coil circuits are assembled and
pulled down, which is required to maintain the coil's design width,
the return bend section tubes, especially those tube runs that are
separated by a straight tube run, will have a degree of freedom due
to manufacturing variability and not maintain a uniform spacing. To
remedy the situation, in the preferred embodiment, one circuit is
designed such that it has a slight under-break compared to 90
degrees and will purposely have an approximate bend angle of 100
degrees. To compliment this, after a straight tube run section of
typically 2 inches or longer, the next bend in the circuit will be
over-broken from 90 degrees to approximately 80 degrees such that
both angles add up to an approximate 180 degree bend. If the tubes
are sloped, as known in the industry, then the two bends, one
slightly over broke and one slightly under broke will add up to an
to an angle slightly greater than 180 degrees. This inventive
return bend circuit design allows for three definite points of
contact in the return bend area which locks the return bends in a
secure fashion such that uniform spacing is preserved in the return
bend sections of the coil. One unique feature of this preferred
embodiment is that the tube circuit may be flipped over such that
there is only one circuit design per coil and the three point
contact is maintained just by flipping the circuits in opposite
directions before the coil is stacked.
[0006] In addition to the embodiments relating to any type of heat
exchanger employed, the type of fan system whether induced or
forced draft, belt drive, gear drive or direct drive can be used
with all embodiments presented. The type of fan whether axial,
centrifugal or other can be used with all embodiments presented.
The type of tubes, material of tubes, tube diameters, tube shape,
whether finned or un-finned, the number of tube passes, number of
return bends, number of increased vertical spaces, can be used with
all embodiments presented. If the indirect coil employs the use of
direct heat exchange medium, as indicated in patent application
Ser. Nos. 13/833,788, 13,833,971 and 62/061,894, the type of fill,
whether efficient counterflow fill, contaminated water application
fills or any material fill can be used with all embodiments
presented.
[0007] Accordingly, it is an object of the present invention to
provide an improved heat exchange apparatus, which could be a
closed circuit fluid cooler, fluid heater, condenser, evaporator,
air cooler or air heater, which includes an indirect heat exchange
section with uniformly spaced return bends.
[0008] It is another object of the present invention to provide an
improved heat exchange apparatus such as a closed circuit fluid
cooler, fluid heater, condenser, evaporator, air cooler or air
heater, including an indirect heat exchange section that allows for
easier assembly (stacking), ease of pull down, ease of
manufacturing and reduction in production cost.
[0009] It is another object of the present invention to provide an
improved heat exchange apparatus such as a closed circuit fluid
cooler, fluid heater, condenser, evaporator, air cooler or air
heater which provides uniform spacing between circuits in the
return bend area to maintain a uniform air passage, promote better
tube wetting of the return bend area, promote higher thermal
capacity and reduced scaling from wet/dry areas resulting from
previously shadowed tubes.
[0010] It is another object of the present invention to provide an
improved heat exchange apparatus such as a closed circuit fluid
cooler, fluid heater, condenser, evaporator, air cooler or air
heater which provides for better inspection and access to the tubes
in the return bend area.
[0011] It is another object of the present invention to provide an
improved heat exchange apparatus such as a closed circuit fluid
cooler, fluid heater, condenser, evaporator, air cooler or air
heater, including an indirect heat exchange section that locks the
return bends in a secure fashion such that uniform spacing is
preserved in the return bend sections of the coil which produces a
higher quality result before and after the hot dip galvanizing
process.
SUMMARY OF THE INVENTION
[0012] The present invention provides an improved heat exchange
apparatus which provides improved quality and performance of
serpentine coils by utilizing a means to maintain a uniform spacing
in the return bend section of the heat exchanger. Assured uniform
spacing on the return bend end allows for ease of circuit assembly
(stacking), ease of coil pull-down, ease of manufacturing,
reduction in production cost, produces a higher quality hot dip
galvanizing process and is a more robust design that tolerates
manufacturing variability issues such as variable tube circuit
length and variable return bend angles. Uniform return bend spacing
also reduces scaling relative to prior art designs which had
wet/dry areas resulting from shadowed tubes which were
non-uniformly spaced, provides for better inspection and access to
the tubes in the return bend area, maintains uniform air passage
around tubes, promotes better tube wetting of the return bend area,
ultimately promoting higher quality heat exchange coils with unit
thermal capacity improvement.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention will be described with reference to the
following drawings, wherein:
[0014] FIG. 1 is a side elevation view in partial section of an
exemplary heat exchanger of a coil/fill type including an indirect
evaporative heat exchanger section and a direct evaporative heat
exchange section incorporating an indirect heat exchange tube
bundle according to the present invention;
[0015] FIG. 2 is a side view of another exemplary embodiment of the
invention in which the indirect coil assembly is provided in a coil
only type heat exchanger;
[0016] FIG. 3 is a plan view in partial section of the heat tube
bundle in the exemplary heat exchangers of FIGS. 1 and 2;
[0017] FIG. 4 is a view taken along line 4-4 of FIG. 3;
[0018] FIG. 5a is an end view of the preferred embodiment double
serpentine coil tube bundle
[0019] FIG. 5b is a side view of the preferred embodiment double
serpentine coil tube bundle
[0020] FIG. 5c is a side view of two circuit tubes of preferred
embodiment double serpentine coil
[0021] FIG. 6 is a side view of two circuit tubes of preferred
embodiment double serpentine coil
[0022] FIG. 7a is a side view of a prior art quad coil
[0023] FIG. 7b is a side view of an embodiment of quad coil
according to the present invention
[0024] FIG. 8a is a side view of a prior art hex coil
[0025] FIG. 8b is a side view of an embodiment of hex coil
according to the present invention
[0026] FIG. 9a is a side view of a prior art octo coil
[0027] FIG. 9b is a side view of an embodiment of octo coil
according to the present invention
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] FIGS. 1,2,3 & 4 are used to describe prior art. Now
referring to FIG. 1, this may be a first exemplary heat exchanger
to which the inventive improved tube coil assembly can be provided.
The heat exchanger apparatus 10 is of the coil/fill type and may
serve as a closed-circuit cooling tower. Generally, apparatus 10
includes an enclosure structure which contains a multi-circuit
indirect evaporative fluid cooling section or indirect heat
exchange section 80, a direct evaporative heat exchange section 90,
a lowermost evaporative liquid collection sump 82 that delivers
liquid to an uppermost water spray assembly 14 through a pipe
distribution system 50 with nozzles 52, and a fan assembly 18. The
water assembly 14 sprays an evaporative liquid downwardly through
indirect heat exchange section 80. The fan 18, driven by motor 42
through belt 40, moves a stream of air through each of the heat
exchange sections 80 and 90, although natural draft is also a
viable means for moving the air. Fan 18 can either be an induced or
forced draft centrifugal fan or a common propeller type of fan.
[0029] Apparatus 10 has many applications in the heat exchange
field. For example, apparatus 10 may be used to cool a single
phase, sensible fluid such as water, which is flowing within an
externally-supplied closed circuit system, or it may be used to
desuperheat and condense a multi-phase, sensible and latent fluid
such as a refrigerant gas, also supplied from an external
closed-circuit system. Finally, the operable field of use for
apparatus 10 also includes duty as a wet air cooler, where the air
discharged is piped offsite to be used as a fresh, cooled air
supply for an operation such as mining. As will become evident, the
tower structures containing the above-mentioned components can also
be arranged and formed in a number of different ways; apparatus 10
is not limited to strictly one shape or arrangement.
[0030] The indirect heat exchange section 80, which is comprised of
a single coil assembly having an array of tubes 66, is superposed
above the direct evaporative heat exchange section 90. The indirect
heat exchange section 80 receives a flowing hot fluid to be cooled
from an offsite process and it is cooled in this section by a
combination of indirect sensible heat exchange and a direct
evaporative heat exchange. The evaporative liquid, which is usually
cooling water, is sprayed downwardly by assembly 14 onto the
indirect section 80, thereby exchanging indirect sensible heat with
the fluid to be cooled, while a stream of ambient air entering
primary air inlet 100, evaporatively cools the evaporative liquid
as the two mediums move generally downwardly through the coil
assembly. In this particular embodiment, the entering air stream
100 is shown entering and flowing in a direction which is generally
parallel or concurrent with the direction of cooling water across
indirect heat exchanger 80, although the air flow stream is not
limited to any particular flow pattern, as will become evident
later on where a crosscurrent air flow pattern will be explained.
Once the air and water cooling mediums reach the bottom side of
indirect section 80, they split, with the air stream being pulled
by fan 18, while the water gravitationally descends into direct
heat exchange section 90. The air is then discharged from apparatus
10 by the fan, while the water is cooled in the direct heat
exchange section as will be explained shortly.
[0031] The direct evaporative heat exchange section 90 functions to
cool the water that is heated and descending from the indirect heat
exchange section 80. Direct evaporative heat exchange section 90 is
comprised of an array of tightly-spaced, parallel, plastic sheets
which form a fill bundle 92, although fill 92 could be formed by
conventional splash-type fill. The hot water received by fill
bundle 92 from indirect section 80 is distributed across each fill
sheet so that a source of outside ambient air which enters a
secondary air inlet 94 evaporatively cools the hot water descending
the sheets. Here, the ambient air stream is shown entering direct
section 90 in a crosscurrent fashion to the descending hot water
draining through the fill bundle 92, although other air flow
schemes can be used. The cooled spray water is then pumped from
lower most collection sump 82 by pump 96 back up to uppermost water
spray assembly 14.
[0032] Now referring to FIG. 2, a second exemplary heat exchanger
to which the inventive tube coil assembly can be provided includes
a generally vertical conduit 10A of sheet metal construction and
having, at different levels in the interior thereof, an upper mist
eliminator assembly 12, a water spray assembly 14A, a coil assembly
16, a fan assembly 18A and a lower water collection sump 20. The
vertical conduit 10A may be of rectangular, generally uniform,
cross-section and comprises vertical front and rear walls 24 and 22
(FIG. 2) and vertical side walls (not shown). A diagonal wall 30
extends downwardly from the front wall 24 to the bottom of the rear
wall 22 to define the lower water collection sump 20. The fan
assembly 18A is positioned behind and below the diagonal wall 30.
However, this is merely one illustrative example of placement.
Other conventional or subsequently developed arrangements can be
substituted. The fan assembly comprises a pair of centrifugal fans
32 each of which has an outlet cowl 34 which projects through the
diagonal wall 30 and into the conduit 10 below the coil assembly
16. The fans 32 may share a common drive axle turned by means of a
driven pulley 38 connected through a belt 40A to a drive motor 42A.
A recirculation line 44 may be arranged to extend through the side
wall (not shown) of the conduit 10A near the bottom of the lower
water collection sump 20 to recirculate water back up to the water
spray assembly 14A by a water pump (not shown). The water spray
assembly 14A comprises spray water pipes 50A fitted with a
plurality of nozzles 52A which emit water sprays to provide an even
distribution of water over the entire coil assembly 16.
[0033] The mist eliminator assembly 12 comprises a plurality of
closely spaced elongated strips 54 which are bent along their
length to form sinuous paths from the region of the water spray
assembly out through the top of the conduit 10.
[0034] Indirect coil assembly 16 is supported by coil brackets 74
which are comprised of a coil assembly having an array of tubes 66.
Now referring to FIGS. 3 and 4, indirect coil assembly 16 according
to either embodiment in FIGS. 1 and 2, comprises an upper manifold
56 and a lower manifold 58 which extend horizontally across the
plurality of cooling tubes 66. The manifolds are held in place by
means of brackets 60 on the side wall 26. Inlet and outlet fluid
conduits 62 and 64 extend through the side wall 26 and communicate
with the upper and lower manifolds 56 and 58 respectively. The
inlet and outlet fluid conduits 62 and 64 may be reversed depending
on the heat transfer process that is taking place. These fluid
conduits are connected to receive a fluid to be cooled or
condensed, for example the refrigerant from a compressor in an air
conditioning system (not shown). A plurality of cooling tubes 66
are connected between the upper and lower manifolds 56 and 58. Each
tube is preferably formed into a serpentine arrangement by means of
180 degree return bends 68 (and 70) near the side walls 26 and 28
so that different segments of each tube extend generally
horizontally across the interior of the conduit 10 back and forth
between the side walls 26 and 28 at different levels in the conduit
along a vertical plane parallel and closely spaced to the plane of
each of the other tubes 66. It will also be noted that the tubes 66
are arranged in alternately offset arrays. It can be seen that each
of the manifolds 56 and 58 is provided with an upper and a lower
row of openings to accept the tubes 66 at these two different
levels. Typically there are tubes anywhere from 2 levels (shown)
and up to eight levels. These tubes may have any suitable outside
diameter D, such as 3/8''-2''. However, in a preferred exemplary
embodiment, they have a diameter of 5/8'' to 1.05''. The return 180
degree bends 68 may also have any suitable bend radius. Further,
the corresponding levels of the segments of adjacent tubes should
be offset vertically from each other by an amount approximately
equal to the 180 degree bend radius. In order to support the tubes
66 at the bends 68 (and 70) there are provided horizontally
extending support rods 72 which are mounted at the wall 26, between
the brackets 60 and, at the wall 28, between brackets 74. The coil
assembly 16 in cross-section comprises arrays of tube segments 66
arranged at different levels or elevations due to the offset
arrangement of adjacent tubes. This assembly is similar to many
prior coil assembly designs.
[0035] Referring now to FIG. 5a, the preferred embodiment of the
invention, double serpentine coil 200 is shown on an end view
looking at the return bend section of the coil. FIG. 5b shows more
detail looking at embodiment 200 from the side view. In FIG. 5b,
upper circuit tube 201 and lower circuit tube 202 are connected to
header 208 and go back and forth and connect back into bottom
header 209. Note that on this coil design, there are a combination
of tight return bends 203 at an approximate bend angle of 180
degrees and then two approximate 90 degree bends separated by
straight tube runs 205 and 206 which create a desired separation
between the generally horizontal tube runs. This desired separation
of generally horizontal tube runs is to increase the spray cooling
zone between tube runs which may be further enhanced by placing
direct heat exchange sections between the separated tube runs as
discussed in patent application Ser. Nos. 13/833,788, 13,833,971
and 62/061,894. Another reason for separating the generally
horizontal tube runs by a vertical distance is to nest in more tube
circuits as will be shown in the FIGS. 7, 8 and 9. FIG. 5c shows
the design of the increased vertical height between generally
horizontal tubes 251 and 252 for embodiment 200 such that they
employ an under-break 224 of approximately 100 degrees and
over-break 222 of approximately 80 degrees. These break tolerances
can be within 10 degrees depending on the desired vertical
separation of tube runs, desired tube slope, tube diameter and
other engineering manufacturing tolerance factors and are not
limitations to the invention. It should be noted that tube 251 has
the same circuit design as tube 252 but is simply flipped before
the coil is stacked. The result of providing an under break 224
followed by a straight tube run then providing over break 222 is to
form the return bend that adds up to approximate 180 degree angle
which allows return bends 205 and 206 to have three points of
contact at points 253, 254, and 255 such that once the coil is
assembled and pulled down, the tubes cannot shift on the return end
side of the coil compared to prior art designs. This three point
contact assures uniform spacing on the return bend end which allows
for ease of circuit stacking, ease of coil pull-down, ease of
manufacturing, reduction in production cost, produces a higher
quality hot dip galvanizing process and is a more robust design
that tolerates manufacturing variability issues such as variable
tube circuit length and variable return bend angles. Uniform return
bend spacing also reduces scaling relative to prior art designs
which had wet/dry areas resulting from shadowed tubes which were
non-uniformly spaced, provides for better inspection and access to
the tubes in the return bend area, maintains uniform air passage
around tubes, promotes better tube wetting of the return bend area,
ultimately promoting higher quality heat exchange coils with unit
thermal capacity improvement. These advantages will be described as
higher quality and performance henceforth.
[0036] Referring now to FIG. 6, embodiment 300, known in the art as
a double serpentine arrangement, shows the intentional vertical
distance 301 with previously described benefits located between
generally horizontal tube runs 306 and 307. Tube circuit 306 has
under-break 302 of approximately 100 degrees and over-break 303 of
approximately 80 degrees. These break tolerances can be within 10
degrees depending on the desired vertical separation of tube runs,
desired tube slope, tube diameter and other engineering
manufacturing tolerance factors. It should be noted that tube
circuit 307 has the same circuit design as tube 306 but is simply
flipped before the coil is stacked. This circuit design allows
return bends in circuit tube 306 and 307 to have three points of
contact at points 310,311 and 312 so that once the coil is
assembled or pulled down, the tubes cannot shift on the return end
side of the coil compared to prior art designs. In addition to
showing an improved circuiting arrangement discussed in patent
application Ser. Nos. 13/833,788, 13,833,971 and 62/061,894, FIG. 6
also serves to show details of improving the circuit structures of
the designs of Quad, Hex and Octo coils in subsequent FIGS. 7, 8
& 9.
[0037] Referring now to FIG. 7a, 400 is known as a prior art design
quad-coil which now has four sets of tubes fed from the header (not
shown). Outer tube sets 401 and 402 can be seen to be slightly
offset from each other in vertical height and both have two
approximate 90 degree bends separated by a straight tube run to
form the approximate 180 degree return bend back to the next
circuit pass. Note that outer tubes 401 and 402 touch each other at
crossing point 405 even if the circuit lengths are not exactly
equal. These tubes may also touch each other along the entire
length of straight tube run between the two 90 degree bends. It is
also possible that these circuits will only touch at the bottom
(not shown). When the coil tubes are assembled and pulled down, due
to manufacturing variability, it is possible that the tubes touch
only at crossing point 405 or only at the bottom (not shown) and
when this happens, the spacing between the tubes becomes
non-uniform and in addition, when hot dip galvanizing, the return
bend tubes may shift to a non-uniformly spaced pattern which
decreases the quality of the coil. The last set of two tubes, 403
and 404, are nested inside of tubes 401 and 402 and these return
bends are typically designed with a 180 degree return bends and as
such touch at one point 406 and do not present an issue of
non-uniform spacing due to their close vertical proximity.
[0038] Referring now to FIG. 7b, embodiment 450 of the invention
shows the improved design of the quad-coil where outer tubes 451
and 452 employ an under-break of approximately 100 degrees and an
over-break of approximately 80 degrees. Embodiment 450 forces three
points of contact at points 455, 456 and 457 such that once the
coil is assembled and pulled down, the tubes cannot shift on the
return end side of the coil compared to the prior art design 400 in
FIG. 7a. This three point contact assures uniform spacing and a
higher quality and performance heat exchange apparatus. It should
be noted that the last set of two tubes, 453 and 454, are nested
inside of tubes 451 and 452 and these return bends are typically
designed with a 180 degree return bends and as such touch at one
point and do not present an issue of non-uniform spacing due to
their close vertical proximity.
[0039] Referring now to FIG. 8a, 500 is known as a prior art design
hex-coil which now has six sets of tubes fed from the header (not
shown). Outer tube sets 501 and 502 can be seen to be slightly
offset from each other in vertical height and both have two
approximate 90 degree bends separated by a straight tube run to
form the approximate 180 degree return bend back to the next
circuit pass. Note that outer tubes 501 and 502 touch each other at
crossing point 507 even if the circuit lengths are not exactly
equal. These tubes may also touch each other along the entire
length of straight tube run between the two 90 degree bends. It is
also possible that these circuits will only touch at the bottom
(not shown). Inner tube sets 503 and 504 can be seen to be slightly
offset from each other in vertical height and both have two
approximate 90 degree bends separated by a straight tube run to
form the approximate 180 degree return bend back to the next
circuit pass. Note that inner tubes 503 and 504 touch each other at
crossing point 508 even if the circuit lengths are not exactly
equal. These tubes may also touch each other along the entire
length of straight tube run between the two 90 degree bends. It is
also possible that these circuits will only touch at the bottom
(not shown). When the coil tubes are assembled and pulled down, due
to manufacturing variability, it is possible that the tubes touch
only at crossing points 507 and 508 (or at the bottom--not shown)
and when this happens, the spacing between the tubes becomes
non-uniform and in addition, when hot dip galvanizing, the tubes
may shift to a non-uniform pattern which decreases the quality of
the coil. Finally, the last set of two tubes, 505 and 506, are
nested inside of tubes 503 and 504 and these return bends are
typically designed with an approximate 180 degree return bend and
as such touch at one point 509 and do not present an issue of
non-uniform spacing due to their close vertical proximity.
[0040] Referring now to FIG. 8b, embodiment 550 of the invention
shows the improved design of the hex-coil where outer tubes 551 and
552 employ an under-break of approximately 100 degrees and an
over-break of approximately 80 degrees. Embodiment 550 also has
inner tubes 553 and 554 employing an under-break of approximately
100 degrees and an over-break of approximately 80 degrees. This
embodiment forces three points of contact at points 557, 558, and
559 and also at 560, 561 and 562 such that once the coil is
assembled and pulled down, the tubes cannot shift on the return end
side of the coil compared to the prior art design 500 in FIG. 8a.
This three point contact assures uniform spacing and a higher
quality and performance heat exchange apparatus. It should be noted
that the last set of two tubes, 555 and 556, are nested inside of
tubes 553 and 554 and these return bends are typically designed
with a 180 degree return bends and as such touch at one point and
do not present an issue of non-uniform spacing due to their close
vertical proximity.
[0041] Referring now to FIG. 9a, 600 is known as a prior art design
a octo-coil which now has eight sets of tubes fed from the header
(not shown). Outer tube sets 601 and 602 can be seen to be slightly
offset from each other in vertical height and both have two
approximate 90 degree bends separated by a straight tube run to
form the approximate 180 degree return bend back to the next
circuit pass. Note that outer tubes 601 and 602 touch each other at
crossing point 609 even if the circuit lengths are not exactly
equal. These tubes may also touch each other along the entire
length of straight tube run between the two 90 degree bends. It is
also possible that these circuits will only touch at the bottom
(not shown). Inner tube sets 603 and 604 can be seen to be slightly
offset from each other in vertical height and both have two
approximate 90 degree bends separated by a straight tube run to
form the approximate 180 degree return bend back to the next
circuit pass. Note that inner tubes 603 and 604 touch each other at
crossing point 610 even if the circuit lengths are not exactly
equal. These tubes may also touch each other along the entire
length of straight tube run between the two 90 degree bends. It is
also possible that these circuits will only touch at the bottom
(not shown). Inner tube sets 605 and 606 can be seen to be slightly
offset from each other in vertical height and both have two
approximate 90 degree bends separated by a straight tube run to
form the approximate 180 degree return bend back to the next
circuit pass. Note that inner tubes 605 and 606 touch each other at
crossing point 611 even if the circuit lengths are not exactly
equal. These tubes may also touch each other along the entire
length of straight tube run between the two 90 degree bends. It is
also possible that these circuits will only touch at the bottom
(not shown). When the coil tubes are assembled and pulled down, due
to manufacturing variability, it is possible that the tubes touch
only at crossing points 609, 610, and 611 (or at the bottom--not
shown) and when this happens, the spacing between the tubes becomes
non-uniform and in addition, when hot dip galvanizing, the tubes
may shift to a non-uniform pattern which decreases the quality of
the coil. Finally, the last set of two tubes, 607 and 608, are
nested inside of tubes 605 and 606 and these return bends are
typically designed with an approximate 180 degree return bend and
as such touch at crossing point 612 and do not present an issue of
non-uniform spacing due to their close vertical proximity.
[0042] Referring now to FIG. 9b, embodiment 650 of the invention
shows the improved design of the octo-coil with outer tubes 651 and
652 employing an under-break of approximately 100 degrees and an
over-break of approximately 80 degrees. Embodiment 650 also has
inner tubes 653 and 654 employing an under-break of approximately
100 degrees and an over-break of approximately 80 degrees.
Embodiment 650 also has inner tubes 655 and 656 employing an
under-break of approximately 100 degrees and an over-break of
approximately 80 degrees. This embodiment forces three points of
contact at points 659, 660 and 661 and also at 662, 663 and 664 and
also at 665, 666, and 667 such that once the coil is assembled and
pulled down, the tubes cannot shift on the return end side of the
coil compared to the prior art design 600 in FIG. 9a. This three
point contact assures uniform spacing and a higher quality and
performance heat exchange apparatus. It should be noted that the
last set of two tubes, 657 and 658, are nested inside of tubes 655
and 656 and these return bends are typically designed with a 180
degree return bends and as such touch at one point and do not
present an issue of non-uniform spacing due to their close vertical
proximity.
* * * * *