FOLDED TUBE MULTIPLE BANK HEAT EXCHANGE UNIT
Background of the Invention
[0001] This invention relates generally to heat exchangers and, more particularly, to a
folded tube multiple bank heat exchange unit.
[0002] Heat exchangers have long been used as evaporators and condensers in heating,
ventilation, air conditioning and refrigeration (HVACR) applications. Historically, these heat
exchangers have been round tube and plate fin (RTPF) heat exchangers. However, all
aluminum flattened tube serpentine fin heat exchangers are finding increasingly wider use in
industry, including the HVACR industry, due to their compactness, thermal-hydraulic
performance, structural rigidity, lower weight and reduced refrigerant charge, in comparison
to conventional RTPF heat exchangers. Flattened tubes commonly used in HVACR
applications typically have an interior subdivided into a plurality of parallel flow channels.
Such flattened tubes are commonly referred to in the art as multi-channel tubes, mini-channel
tubes or micro-channel tubes. Flattened tube serpentine fin heat exchangers may include a
single tube bank of flattened tubes and two or multiple tube banks of flattened tubes.
[0003] Existing manufacturing techniques for flattened tubes involve an extrusion process.
The extrusion process is costly and often requires specialty manufacturing equipment, often
complicating the supply chain. Furthermore, the extrusion process is limited to certain class
of aluminum alloys, due to manufacturing limitations and production cost, often
detrimentally affecting corrosion durability of the flattened tube and the entire heat
exchanger. There also exist techniques for forming a folded, single bank flattened tube from
sheet material.
Summary of the Invention
[0004] In an aspect, a multiple bank, flattened tube heat exchange unit includes a first tube
bank including a flattened first tube segment extending longitudinally between a first
manifold and a second manifold; and a second tube bank including a flattened second tube
segment extending longitudinally between the first manifold and the second manifold, the
second tube bank disposed behind the first tube bank; wherein an outer surface of the first
tube segment and an outer surface of the second tube segment are formed from a single sheet
of material.
[0005] In another aspect, a method of forming a multiple bank, flattened tube heat
exchange unit includes obtaining a single sheet of material, the single sheet of material
having a longitudinal axis; bending a first portion of the single sheet of material towards the
longitudinal axis to define an outer surface of a first tube segment; and bending a second
portion of the single sheet of material towards the longitudinal axis to define an outer surface
of a second tube segment.
[0006] In another aspect, a method of forming a multiple bank, flattened tube heat
exchange unit includes obtaining a single sheet of material, the single sheet of material
having a longitudinal axis; and bending a first portion of the single sheet of material towards
the longitudinal axis to define an outer surface of a first tube segment and define an outer
surface of a second tube segment.
[0007] Other aspects, features, and techniques of embodiments of the invention will
become more apparent from the following description taken in conjunction with the
drawings.
Brief Description of the Drawings
[0008] For further understanding of the disclosure, reference will be made to the following
detailed description which is to be read in connection with the accompanying drawing,
where:
[0009] FIG. 1 is a diagrammatic illustration of an exemplary embodiment of a multiple
tube bank, flattened tube finned heat exchange unit;
[0010] FIG. 2 is a side elevation view, partly in section, illustrating an exemplary
embodiment of a fin and a set of integral flattened tube segments of the heat exchange unit of
FIG. 1;
[0011] FIG. 3 depicts a sheet of material for forming a first tube segment and a second
tube segment in an exemplary embodiment;
[0012] FIGs. 4-6 depict forming a first tube segment and a second tube segment in an
exemplary embodiment;
[0013] FIGs. 7-9 depict forming a first tube segment and a second tube segment in an
exemplary embodiment;
[0014] FIGs. 10-11 depict an orientation of an edge of sheet material in exemplary
embodiments;
[0015] FIGs. 12-14 depict forming a first tube segment and a second tube segment in an
exemplary embodiment;
[0016] FIG. 15 is a flowchart of a process of forming a first tube segment and a second
tube segment in an exemplary embodiment; and
[0017] FIG. 16 is a top down view of a heat exchange unit in an exemplary embodiment.
Detailed Description
[0018] An exemplary embodiment of a multiple bank flattened tube finned heat exchange
unit in accordance with the disclosure, generally designated 10, is depicted in perspective
illustration in FIG. 1. As depicted therein, the multiple bank flattened tube finned heat
exchange unit 10 includes a first tube bank 100 and a second tube bank 200 that is disposed
behind the first tube bank 100, that is downstream with respect to air flow, A, through the
heat exchanger. The first tube bank 100 may also be referred to herein as the front heat
exchanger slab 100 and the second tube bank 200 may also be referred to herein as the rear
heat exchanger slab 200.
[0019] The first tube bank 100 includes a first manifold 102, a second manifold 104
spaced apart from the first manifold 102, and a plurality of heat exchange tube segments 106,
including at least a first and a second tube segment, extending longitudinally in spaced
parallel relationship between and connecting the first manifold 102 and the second manifold
104 in fluid communication. The second tube bank 200 includes a first manifold 202, a
second manifold 204 spaced apart from the first manifold 202, and a plurality of heat
exchange tube segments 206, including at least a first and a second tube segment, extending
longitudinally in spaced parallel relationship between and connecting the first manifold 202
and the second manifold 204 in fluid communication. Each set of manifolds 102, 202 and
104, 204 disposed at either side of the dual bank heat exchanger 10 may comprise separate
paired manifolds, may comprise separate chambers within an integral one-piece folded
manifold assembly or may comprise separate chambers within an integral fabricated (e.g.
extruded, drawn, rolled and welded) manifold assembly. Each tube bank 100, 200 may
further include "dummy" tubes (not shown) extending between its first and second manifolds
typically at the top of the tube bank and at the bottom of the tube bank. These "dummy"
tubes do not convey refrigerant flow, but add structural support to the tube bank and protect
the uppermost and lowermost fins.
[0020] Referring now to FIG. 2, each of the heat exchange tube segments 106, 206
comprises a flattened heat exchange tube having a leading edge 108, 208, a trailing edge 110,
210, an upper surface 112, 212, and a lower surface 114, 214. The leading edge 108, 208 of
each heat exchange tube segment 106, 206 is upstream of its respective trailing edge 110, 210
with respect to airflow through the heat exchange unit 10. In the embodiment depicted in
FIG. 2, the respective leading and trailing portions of the flattened tube segments 106, 206
are rounded thereby providing blunt leading edges 108, 208 and trailing edges 110, 210.
However, it is to be understood that the respective leading and trailing portions of the
flattened tube segments 106, 206 may be formed in other configurations.
[0021] The interior flow passage of each of the heat exchange tube segments 106, 206 of
the first and second tube banks 100, 200, respectively, may be divided by interior walls into a
plurality of discrete flow channels 120, 220 that extend longitudinally the length of the tube
segment from an inlet end of the tube segment to an outlet end of the tube segment and
establish fluid communication between the respective headers of the first and the second tube
banks 100, 200. In the embodiment of the multi-channel heat exchange tube segments 106,
206 depicted in FIG. 2, the heat exchange tube segments 206 of the second tube bank 200
have a greater width than the heat exchange tube segments 106 of the first tube bank 100.
Also, the interior flow passages of the wider heat exchange tube segments 206 may be
divided into a greater number of discrete flow channels 220 than the number of discrete flow
channels 120 into which the interior flow passages of the heat exchange tube segments 106
are divided. The flow channels 120, 220 may have a circular cross-section, a rectangular
cross-section or other non-circular cross-section.
[0022] The second tube bank 200, i.e. the rear heat exchanger slab, is disposed behind the
first tube bank 100, i.e. the front heat exchanger slab, with respect to the airflow direction,
with each heat exchange tube segment 106 directly aligned with a respective heat exchange
tube segment 206 and with the leading edges 208 of the heat exchange tube segments 206 of
the second tube bank 200 spaced from the trailing edges 110 of the heat exchange tube
segments of the first tube bank 100 by a desired spacing, G.
[0023] In the embodiment depicted in FIG. 2, an elongated web 40 or a plurality of
spaced web members 40 span the desired spacing, G, along at least of portion of the length of
each aligned set of heat exchange tube segments 106, 206. For a further description of a dual
bank, flattened tube finned heat exchanger unit wherein the heat exchange tubes 106 of the
first tube bank 100 and the heat exchange tubes 206 of the second tube bank 200 are
connected by an elongated web or a plurality of web members, reference is made to U.S.
provisional application serial number 61/593,979, filed February 2, 2012, the entire
disclosure of which is hereby incorporated herein by reference.
[0024] Referring still to FIGs. 1 and 2, the flattened tube finned heat exchange unit 10
disclosed herein further includes a plurality of folded fins 320. Each folded fin 320 is formed
of a single continuous strip of fin material tightly folded in a ribbon-like serpentine fashion
thereby providing a plurality of closely spaced fins 322 that extend generally orthogonal to
the flattened heat exchange tube segments 106, 206. Typically, the fin density of the closely
spaced fins 322 of each continuous folded fin 320 may be about 16 to 25 fins per inch, but
higher or lower fin densities may also be used. Heat exchange between the refrigerant flow,
R, and air flow, A, occurs through the outside surfaces 112, 114 and 212, 214, respectively,
of the heat exchange tube segments 106, 206, collectively forming the primary heat exchange
surface, and also through the heat exchange surface of the fins 322 of the folded fin 320,
which forms the secondary heat exchange surface.
[0025] In the depicted embodiment, the depth of each of the ribbon-like folded fin 320
extends at least from the leading edge 108 of the first tube bank 100 to the trailing edge of
210 of the second bank 200, and may overhang the leading edge 108 of the first tube bank
100 or/and trailing edge 210 of the second tube bank 200 as desired. Thus, when a folded fin
320 is installed between a set of adjacent multiple tube, flattened heat exchange tube
assemblies in the array of tube assemblies of the assembled heat exchange unit 10, a first
section 324 of each fin 322 is disposed within the first tube bank 100, a second section 326 of
each fin 322 spans the spacing, G, between the trailing edge 110 of the first tube bank 100
and the leading edge 208 of the second tube bank 200, and a third section 328 of each fin 322
is disposed within the second tube bank 200. In an embodiment, each fin 322 of the folded
fin 320 may be provided with louvers 330, 332 formed in the first and third sections,
respectively, of each fin 322.
[0026] The multiple bank, flattened tube heat exchange unit 10 disclosed herein is
depicted in a cross-counterflow arrangement wherein refrigerant (labeled "R") from a
refrigerant circuit (not shown) of a refrigerant vapor compression system (not shown) passes
through the manifolds and heat exchange tube segments of the tube banks 100, 200, in a
manner to be described in further detail hereinafter, in heat exchange relationship with a
cooling media, most commonly ambient air, flowing through the airside of the heat
exchanger 10 in the direction indicated by the arrow labeled "A" that passes over the outside
surfaces of the heat exchange tube segments 106, 206 and the surfaces of the folded fins 320.
The air flow first passes transversely across the upper and lower horizontal surfaces 112, 114
of the heat exchange tube segments 106 of the first tube bank, and then passes transversely
across the upper and lower horizontal surfaces 212, 214 of the heat exchange tube segments
206 of the second tube bank 200. The refrigerant passes in cross-counterflow arrangement to
the airflow, in that the refrigerant flow passes first through the second tube bank 200 and then
through the first tube bank 100. The multiple tube bank, flattened tube finned heat exchange
unit 10 having a cross-counterflow circuit arrangement yields superior heat exchange
performance, as compared to the crossflow or cross-parallel flow circuit arrangements, as
well as allows for flexibility to manage the refrigerant side pressure drop via implementation
of tubes of various widths within the first tube bank 100 and the second tube bank 200.
[0027] A method of manufacturing heat exchange tube segments 106, 206 and at least one
web 40 is described with reference to FIGs. 3-6. The manufacturing method includes folding
a sheet of stock material to define tube segments 106, 206 and at least one web 40. FIG. 3
depicts a sheet 410 of stock material such as a metal (e.g., aluminum). Sheet 410 may be clad
on both sides with a brazing alloy. The sheet 410 is stamped or punched to define a notch
412 along a lateral edge of the sheet 410. A notch 412 may be formed at each distal end, or
lateral edge, of sheet 410. Notches 412 define how deep first tube segment 106 and second
tube segment 206 can be inserted into manifolds 102, 104, 202 and 204. Slots 414 are also
stamped or punched from sheet 410. Slots 414 promote water drainage (e.g., condensate
drainage) and prevent thermal cross-conduction between first tube segments 106 and second
tube segments 206. Slots 414 are formed in the interior of sheet 410, intermediate the distal
ends of sheet 410. Notches 412 and slots 414 are formed along a central, longitudinal axis of
sheet 410. The remaining material along longitudinal axis, C, are webs 40, that join the first
tube segment 106 and second tube segment 206. It is understood that axis C need not be
centrally located on sheet 410, in embodiments where tube segment 106 and tube segment
206 have different widths.
[0028] The first tube segment 106 and second tube segment 206 are formed, in an
exemplary embodiment, as shown in FIGs. 4-6. Referring the FIG. 4, a first corrugated
section 420 is formed along a first longitudinal edge of sheet 410. The first corrugated
section 420 may be stamped, punched, or otherwise formed in sheet 410. First corrugated
section 420 includes a series of peaks and troughs that eventually define flow channels 120 of
first tube segment 106. The peaks and troughs are shown as square in FIG. 4, but it is
understood that other cross-sections may be used in first corrugated section 420. A second
corrugated section 422 is formed along a second longitudinal edge of sheet 410. The second
corrugated section 422 may be stamped, punched, or otherwise formed in sheet 410. Second
corrugated section 422 includes a series of peaks and troughs that eventually define flow
channels 220 of second tube segment 206. The peaks and troughs are shown as square in
FIG. 4, but it is understood that other cross-sections may be used in second corrugated
section 422.
[0029] As shown in FIGs. 4 and 5, first corrugated section 420 is bent about 180 degrees
along a longitudinal axis parallel to axis C, inwards towards axis C, to form a first bend 424
of first section 420. Similarly, second corrugated section 422 is bent about 180 degrees along
a longitudinal axis parallel to axis C, inwards towards axis C to form a first bend 426 of
second section 422. As shown in FIGs. 5 and 6, again the first corrugated section 420 is bent
about 180 degrees along a longitudinal axis parallel to axis C, inwards towards axis C, to
form a second bend 425 of first section 420. Similarly, second corrugated section 422 is bent
about 180 degrees along a longitudinal axis parallel to axis C, inwards towards axis C, to
form a second bend 427 of second section 422. The two bending steps form first tube
segment 106 and second tube segment 206. The corrugated sections 420 and 422 define the
flow channels 120 and 220, respectively, in first tube segment 106 and second tube segment
206. First bend 424 of first section 420 corresponds to trailing edge 110 of first tube segment
106. Second bend 425 of first section 420 corresponds to leading edge 108 of first tube
segment 106. First bend 426 of second section 422 corresponds to leading edge 208 of
second tube segment 206. Second bend 427 of second section 422 corresponds to trailing
edge 210 of second tube segment 206. In FIGs. 4-6, the outer surface of the first tube
segment 106, flow channels 120, the outer surface of the second tube segment 206, flow
channels 220 and the at least one web 40 are formed from a single sheet 410.
[0030] The formed first tube segment 106 and second tube segment 206 are joined by at
least one web 40. The first tube segment 106 and second tube segment 206 may then be
brazed using known techniques, such as controlled atmosphere brazing. The brazing process
seals the corrugated sections 420 and 422 to the adjacent sheet material to seal first tube
segment 106 and second tube segment 206. In an alternative embodiment, a plurality of first
tube segments 106 and second tube segments 206 are assembled to manifolds 102, 104, 202
and 204, along with folded fins 320. The entire assembly may then be brazed using known
techniques, such as controlled atmosphere brazing.
[0031] An alternative method of manufacturing heat exchange tube segments 106, 206
and web 40 is described with reference to FIGs. 7-9. The manufacturing method includes
folding the sheet 410 of stock material to define tube segments 106, 206 and at least one web
40. Prior to folding, as described above with reference to FIG. 3, one or more notches 412
and/or one or more slots 414 may be formed in sheet 410.
[0032] The first tube segment 106 and second tube segment 206 are formed as shown in
FIGs. 7-9. Referring the FIG. 7, a first corrugated section 420 is formed along a first
longitudinal axis of sheet 410, at an interior of sheet 410, proximate to a central axis, C. The
first corrugated section 420 may be formed by a separate sheet of material placed on top of
sheet 410. First corrugated section 420 includes a series of peaks and troughs that eventually
define flow channels 120 of first tube segment 106. The peaks and troughs are shown as
square in FIG. 7, but it is understood that other cross-sections may be used in first corrugated
section 420. A second corrugated section 422 is formed along a second longitudinal axis of
sheet 410, at an interior of sheet 410, proximate to a central axis, C, and on an opposite side
of axis C as first corrugated section 420. The second corrugated section 422 may be formed
by a separate sheet of material placed on top of sheet 410. Second corrugated section 422
includes a series of peaks and troughs that eventually define flow channels 220 of second
tube segment 206. The peaks and troughs are shown as square in FIG. 7, but it is understood
that other cross-sections may be used in second corrugated section 422.
[0033] As shown in FIGs. 7 and 8, a first section 4 11 of sheet 410 is bent about 180
degrees along a longitudinal axis parallel to axis C, inwards towards axis C to form a first
bend 424 of first section 411. Similarly, second section 413 is bent about 180 degrees along
a longitudinal axis parallel to axis C, inwards towards axis C to form a first bend 426 of
second section 413. As shown in FIGs. 8 and 9, the first section 411 is bent along a
longitudinal axis parallel to axis C, downwards towards axis C, to form a second bend 425 of
first section 411. Similarly, second section 413 is bent along a longitudinal axis parallel to
axis C, downwards towards axis C, to form a second bend 427 of second section 413. The
two bending steps form first tube segment 106 and second tube segment 206. The corrugated
sections 420 and 422 define the flow channels 120 and 220, respectively, in first tube
segment 106 and second tube segment 206. First bend 424 of first section 411 corresponds to
leading edge 108 of first tube segment 106. Second bend 425 of first section 420 corresponds
to trailing edge 110 of first tube segment 106. First bend 426 of second section 413
corresponds to trailing edge 210 of second tube segment 206. Second bend 427 of second
section 413 corresponds to leading edge 208 of second tube segment 206.
[0034] The outer surface of the first tube segment 106, the outer surface of the second tube
segment 206, and the at least one web 40 are formed from a single sheet of stock material
410.
[0035] The formed first tube segment 106 and second tube segment 206 are joined by at
least one web 40. The first tube segment 106 and second tube segment 206 may then be
brazed using known techniques, such as controlled atmosphere brazing. The brazing process
seals the corrugated sections 420 and 422 to the adjacent sheet material to seal first tube
segment 106 and second tube segment 206. In an alternative embodiment, a plurality of first
tube segments 106 and second tube segments 206 are assembled to manifolds 102, 104, 202
and 204, along with folded fins 320. The entire assembly may then be brazed using known
techniques, such as controlled atmosphere brazing.
[0036] The folding directions of sheet 410 in FIGs. 4-9 are exemplary, and a number of
differing folding orientations may be used in forming first tube segment 106 and second tube
segment 206. For example, FIG. 10 is an enlarged view of second bend 425 from FIG. 9. As
shown in FIG. 10, an edge 429 of sheet 410 defines the end of bend 425. Edge 429 may be
bent inwardly towards the interior of tube segment 106. As shown in FIG. 11, edge 429 may
be bent outwardly towards the web 40. This is just one example of alternative bend
directions that may be used over several sections of first tube segment 106 and second tube
segment 206. Further, localized features, such as nesting pockets, overlaps, and ribs can be
incorporated into the design to promote brazing, structural strength, etc.
[0037] An alternative method of manufacturing heat exchange tube segments 106, 206 and
web 40 is described with reference to FIGs. 12-14. The manufacturing method includes
folding the sheet 410 of stock material to define tube segments 106, 206 and at least one web
40. Prior to folding, as described above with reference to FIG. 3, one or more notches 412
and/or one or more slots 414 may be formed in sheet 410 between locations of first
corrugated section 420 and second corrugated section 422.
[0038] The first tube segment 106 and second tube segment 206 are formed as shown in
FIGs. 12-14. Referring the FIG. 12, a first corrugated section 420 is formed along a first
longitudinal axis of sheet 410. The first corrugated section 420 may be formed by stamping
sheet 410 or may be a separate sheet of material placed on top of sheet 410. First corrugated
section 420 includes a series of peaks and troughs that eventually define flow channels 120 of
first tube segment 106. The peaks and troughs are shown as square in FIG. 12, but it is
understood that other cross-sections may be used in first corrugated section 420.
[0039] A second corrugated section 422 is formed along a second longitudinal axis of
sheet 41, on the same side of axis C as first corrugated section 420. The second corrugated
section 422 may be formed by stamping sheet 410 or may be separate sheet of material
placed on top of sheet 410. Second corrugated section 422 includes a series of peaks and
troughs that eventually define flow channels 220 of second tube segment 206. The peaks and
troughs are shown as square in FIG. 12, but it is understood that other cross-sections may be
used in second corrugated section 422.
[0040] Also formed in sheet 410 is a rib 440, which may be formed by stamping sheet
410. Rib 440 is generally rectangular and is formed along a longitudinal axis parallel to
longitudinal axis, C. Rib 440 has a width substantially corresponding to web 40. One or
more notches 412 and one or more slots 414 may be formed in rib 440, to correspond notches
and/or slots formed in web 40 between first corrugated section 420 and second corrugated
section 422.
[0041] As shown in FIGs. 12 and 13, a first section 411 of sheet 410, including rib 440, is
bent about 180 degrees along a longitudinal axis parallel to axis C, inwards towards axis C to
form a first bend 424 of first section 411. This places rib 440 juxtaposed web 40 between
first corrugated section 420 and second corrugated section 422. As shown in FIGs. 13 and
14, an edge of first section 411 is bent along a longitudinal axis parallel to axis C, towards
axis C, to form a second bend 426 of first section 411. The bending steps form first tube
segment 106 and second tube segment 206. The corrugated sections 420 and 422 define the
flow channels 120 and 220, respectively, in first tube segment 106 and second tube segment
206. First bend 424 of first section 411 corresponds to trailing edge 210 of second tube
segment 206. Second bend 426 of first section 4 11 corresponds to leading edge 108 of first
tube segment 106. A first interior wall 425 of rib 440 corresponds to trailing edge 110 of first
tube segment 106. A second interior wall 427 of rib 440 corresponds to leading edge 208 of
second tube segment 206.
[0042] The outer surface of the first tube segment 106, the outer surface of the second tube
segment 206, and the at least one web 40 are formed from a single sheet of stock material
410.
[0043] The formed first tube segment 106 and second tube segment 206 are joined by at
least one web 40. The first tube segment 106 and second tube segment 206 may then be
brazed using known techniques, such as controlled atmosphere brazing. The brazing process
seals the corrugated sections 420 and 422 to the adjacent sheet material to seal first tube
segment 106 and second tube segment 206. In an alternative embodiment, a plurality of first
tube segments 106 and second tube segments 206 are assembled to manifolds 102, 104, 202
and 204, along with folded fins 320. The entire assembly may then be brazed using known
techniques, such as controlled atmosphere brazing.
[0044] FIG. 15 is a flowchart of a process of forming a first tube segment and second tube
segment in an exemplary embodiment. The process begins at 500 where sheet 410 is
obtained. Sheet 410 may be a metal (e.g. aluminum) and may be clad on both sides with a
brazing alloy. At 502, notches 412 may be formed at each end of sheet 410, about a
longitudinal axis. Slots 414 may also be formed at 502 along the longitudinal axis.
[0045] At 504, the corrugated sections 420 and 422 are formed on sheet 410. This may
entail stamping or punching the corrugated sections into sheet 410. Alternatively, as shown
in FIGs. 7-9, this may entail using a second sheet of material having the corrugations formed
therein. At 506, the outer sections of the sheet material are bent inwards towards the
longitudinal axis to form the first tube segment 106 and second tube segment 206. At 508,
brazing is performed. This may entail brazing just the first tube segment 106 and second tube
segment 206. Alternatively, a plurality of first tube segments 106 and second tube segments
206 are assembled to manifolds 102, 104, 202 and 204, along with folded fins 320, and then
brazing is performed.
[0046] Forming the tube segments 106, 206 and web 40 by folding sheet 410 eliminates
the need for an extrusion process, allowing tube fabrication at the heat exchanger
manufacturer site, reducing logistics complexity, improving reliability and providing
noticeable cost savings. Additionally, the material system limitations imposed by the
extrusion process can be avoided and heat exchanger corrosion durability significantly
improved.
[0047] It is understood that various tube folding patterns can be employed and will not
deviate from the scope and spirit of the invention. Furthermore, at least one of the tube
segments 106, 206 may not have internal ports and may carry a separate fluid. In the latter
case, the manifolds in the first tube bank 100 and in the second tube bank 200 are separated,
while the tube banks have independent inlet pipes and outlet pipes. This is shown in FIG. 16,
which is a top down view of heat exchange unit 10, where manifolds 102, 104 of first tube
bank 100 are not in fluid communication with manifolds 202, 204 of tube bank 200. First
tube bank 100 and second tube bank 200 have independent inlet pipes 142, 242 and outlet
pipes 144, 244, respectively.
[0048] While the present invention has been particularly shown and described with
reference to the exemplary embodiments as illustrated in the drawing, it will be recognized
by those skilled in the art that various modifications may be made without departing from the
spirit and scope of the invention. Therefore, it is intended that the present disclosure not be
limited to the particular embodiment(s) disclosed as, but that the disclosure will include all
embodiments falling within the scope of the appended claims.

We Claim:
1. A multiple bank, flattened tube heat exchange unit comprising:
a first tube bank including a flattened first tube segment extending longitudinally
between a first manifold and a second manifold; and
a second tube bank including a flattened second tube segment extending
longitudinally between the first manifold and the second manifold, the second tube bank
disposed behind the first tube bank;
wherein an outer surface of the first tube segment and an outer surface of the second
tube segment are formed from a single sheet of material.
2. The multiple bank, flattened tube heat exchange unit of claim 1 further
comprising:
at least one web joining the first tube segment and the second tube segment.
3. The multiple bank, flattened tube heat exchange unit of claim 2 wherein:
the outer surface of the first tube segment, the outer surface of the second tube
segment and the at least one web are formed from the single sheet of material.
4. The multiple bank, flattened tube heat exchange unit of claim 1 further
comprising:
a first corrugated section positioned inside the first tube segment, the first corrugated
section defining plurality of discrete flow channels in the first tube segment.
5. The multiple bank, flattened tube heat exchange unit of claim 4 wherein:
the first corrugated section and the outer surface of the first tube segment are formed
from the single sheet of material.
6. The multiple bank, flattened tube heat exchange unit of claim 5 further
comprising:
a second corrugated section positioned inside the second tube segment, the second
corrugated section defining plurality of discrete flow channels in the second tube segment.
7. The multiple bank, flattened tube heat exchange unit of claim 6 wherein:
the second corrugated section and the outer surface of the second tube segment are
formed from the single sheet of material.
8. The multiple bank, flattened tube heat exchange unit of claim 6 wherein:
the second corrugated section is formed from a second sheet of material.
9. The multiple bank, flattened tube heat exchange unit of claim 4 wherein:
the first corrugated section is formed from a second sheet of material.
10. The multiple bank, flattened tube heat exchange unit of claim 1 further
comprising:
a notch formed in the single sheet of material, the notch positioned between the first
tube segment and the second tube segment, the notch positioned proximate to a distal end of
the first tube segment and the second tube segment.
11. The multiple bank, flattened tube heat exchange unit of claim 1 further
comprising:
at least one slot formed in the single sheet of material, the slot positioned between the
first tube segment and the second tube segment, the slot positioned intermediate distal ends of
the first tube segment and the second tube segment.
12. A method of forming a multiple bank, flattened tube heat exchange unit, the
method comprising:
obtaining a single sheet of material, the single sheet of material having a longitudinal
axis;
bending a first portion of the single sheet of material towards the longitudinal axis to
define an outer surface of a first tube segment; and
bending a second portion of the single sheet of material towards the longitudinal axis
to define an outer surface of a second tube segment.
13. The method of claim 12 further comprising:
defining a first corrugated section, the first corrugated section defining plurality of
discrete flow channels in the first tube segment.
14. The method of claim 13 wherein:
the first corrugated section includes forming the first corrugated section in the first
portion of the single sheet of material.
15. The method of claim 14 further comprising:
defining a second corrugated section, the second corrugated section defining plurality
of discrete flow channels in the second tube segment.
16. The method of claim 15 wherein:
the second corrugated section includes forming the second corrugated section in the
second portion of the single sheet of material.
17. The method of claim 15 wherein:
the second corrugated section includes forming the second corrugated section in a
second sheet of material.
18. The method of claim 13 wherein:
the first corrugated section includes forming the first corrugated section in a second
sheet of material.
19. The method of claim 12 further comprising:
forming a notch in the sheet of material, the notch positioned along the longitudinal
axis at a distal end of the sheet of material.
20. The method of claim 12 further comprising:
forming at least one slot in the sheet of material, the slot positioned along the
longitudinal axis intermediate distal ends of the sheet of material.
21. The method of claim 12 further comprising:
brazing the first tube segment and the second tube segment.
22. The method of claim 12 further comprising:
assembling the first tube segment and the second tube segment with a first manifold
and a second manifold; and
brazing the assembled first tube segment, the second tube segment, the first manifold
and the second manifold.
23. The method of claim 12 wherein:
the single sheet of material is cladded with a brazing material.
24. A method of forming a multiple bank, flattened tube heat exchange unit, the
method comprising:
obtaining a single sheet of material, the single sheet of material having a longitudinal
axis;
bending the first portion of the single sheet of material towards the longitudinal axis
to define an outer surface of a first tube segment and define an outer surface of a second tube
segment.
25. The method of claim 24 further comprising:
forming a first corrugated section and a second corrugated section in the sheet of
material prior to bending.
26. The method of claim 25 further comprising:
forming a rib in a first portion prior to the bending.
27. The method of claim 26 wherein:
upon the bending, the rib is positioned between the first corrugated section and the
second corrugated section.
28. The method of claim 26 further comprising:
forming a notch in the single sheet of material, the notch located to be positioned
between the first tube segment and the second tube segment, the notch positioned proximate
to a distal end of the first tube segment and the second tube segment; and
forming a notch in the rib, wherein upon bending the notch in the rib is aligned with
the notch in the single sheet of material.
29. The method of claim 26 further comprising:
forming at least one slot in the single sheet of material, the slot located to be
positioned between the first tube segment and the second tube segment, the slot positioned
intermediate distal ends of the first tube segment and the second tube segment; and
forming at least one slot in the rib, wherein upon bending the at least one slot in the
rib is aligned with the at least one slot in the single sheet of material.