Title: Fluid flow distribution device
Abstract: A fluid flow distribution device (10) is provided for use in a heat exchanger (12) having multiple heat exchange units (14) that receive a fluid flow (18) from an fluid inlet (16). The device includes a plurality of tortuous flow paths (31) to direct distributed portions of the fluid flow (18) from the inlet (16) to the heat exchange units (14). Each tortuous flow path (31) is defined by a pair of flow chamber plates (24,26), and an orifice plate (28) sandwiched between the flow chamber plates (24,26). Each tortuous flow path (31) includes a series (34) of orifices (36) extending through the orifice plate (28), a first pattern (38) of first flow chambers (40) formed in one of the flow chamber plates (24,26) and aligned with sequential pairs of the orifices (36), and a second pattern (42) of second flow chambers (44) formed in the other of the flow chamber plates (24,26) and offset with respect to the first pattern (38) and the pairs of orifices (36).
Patent Number: 6,892,805 Issued on 05/17/2005 to Valensa
| Inventors:
|
Valensa; Jeroen (New Berlin, WI)
|
| Assignee:
|
Modine Manufacturing Company (Racine, WI)
|
| Appl. No.:
|
818292 |
| Filed:
|
April 5, 2004 |
| Current U.S. Class: |
165/174; 165/96; 165/173 |
| Intern'l Class: |
F28F 009/02; F28F027/00 |
| Field of Search: |
165/173-175,158-159,143,805,802,96,111,115
62/525,504
137/271,573
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: Duong; Tho v
Attorney, Agent or Firm: Wood, Phillips, Katz, Clark & Mortimer
Claims
1. A fluid flow distribution device for use in a heat exchanger having multiple
heat exchange units that receive a fluid flow from a fluid inlet; the device comprising:
a plurality of tortuous flow path units to direct the fluid flow from the inlet
to said heat exchange units, said tortuous flow path units lying in a common plane,
each tortuous flow path unit comprising a pair of flow chamber plates, an orifice
plate sandwiched between the flow chamber plates, and a tortuous flow path,
the tortuous flow path comprising
a series of orifices extending through said orifice plate,
a first pattern of first flow chambers formed in one of said flow chamber plates
and aligned with sequential pairs of said orifices, and
a second pattern of second flow chambers formed in the other of said flow chamber
plates and offset with respect to said first pattern and said pairs of orifices,
each pair of said orifices aligned with one of said first flow chambers and with
a pair of said second flow chambers to direct said fluid flow to said one of said
first chambers from one of said pair of said second chambers via one of the orifices
of the pair of said orifices and from said one of said first chambers to the other
of said pair of said second chambers via the other orifice of said pair of said
orifices such that the fluid flow travels along said tortuous flow path passing
sequentially through said series of orifices while alternating between said first
and second flow chambers.
2. The fluid flow distribution device of claim 1 wherein said first and second
flow chambers of each of the tortuous flow path units are open to both sides of
the corresponding flow chamber plate and are enclosed by said orifice plate on
one side of each of the flow chamber plates and by respective end plates on the
opposite sides of the flow chamber plates.
3. The fluid flow distribution device of claim 2 wherein:
one of said end plates has an inlet opening connected to said fluid inlet and
aligned with an initial one of said first and second flow chambers to direct the
fluid flow from the fluid inlet to the tortuous flow path; and
one of said end plates has an outlet opening aligned with a final one of said
first and second flow chambers and connected to at least one of said heat exchange
units to direct the fluid flow from the tortuous flow path to said at least one
of said heat exchange units.
4. The fluid flow distribution device of claim 3 wherein said inlet and outlet
openings are not in the same end plate.
5. The fluid flow distribution device of claim 4 further comprising a pair of
flow manifold plates, and where the plurality of tortuous flow path units are sandwiched
between the flow manifold plates, one of said flow manifold plates including a
flow path channel aligned with the fluid inlet and each of the inlet openings in
each of the tortuous flow path units to direct the fluid flow from the fluid inlet
to each of the inlet openings, the other of the flow manifold plates including
a plurality of discrete flow path channels, each of said discrete flow path channels
aligned with one of said outlet openings and the associated at least one of said
exchange units to direct the fluid flow from the one of said outlet openings to
the associated at least one of said heat exchange units.
6. The fluid flow distribution device of claim 5 further comprising:
an inlet plate overlaying said one of said flow manifold plates and including
an inlet port therein aligned with said fluid inlet and said flow path channel; and
a header plate overlaying said other of said flow manifold plates and including
a plurality of openings, each opening receiving one of said heat exchange units
and aligned with one of said discrete flow channels.
7. The fluid flow distribution device of claim 1 wherein:
the series of orifices of all of the tortuous flow path units are located in
a single orifice plate;
the first patterns of all of said plurality of tortuous flow path units are located
in a single flow chamber plate; and
the second patterns of all of said plurality of tortuous flow path units are
located in a single flow chamber plate.
8. The fluid flow distribution device of claim 1 wherein said first and second
flow chambers all have the same shape and size.
9. The fluid flow distribution device of claim 8 wherein said first and second
flow chambers are hexagonal shaped.
10. The fluid flow distribution device of claim 8 wherein said first and second
flow chamber plates are identical in construction.
11. The fluid flow distribution device of claim 8 wherein said series of orifices
are arranged in a serpentine pattern.
12. A fluid flow distribution device for use in a heat exchanger having multiple
heat exchange units that receive a fluid flow from a fluid inlet; the device comprising:
a plurality of tortuous flow path units to direct the fluid flow from the inlet
to said heat exchange units, said tortuous flow path units lying in a common plane,
each tortuous flow path unit comprising a pair of flow chamber plates, an orifice
plate sandwiched between the flow chamber plates, and a tortuous flow path,
the tortuous flow path comprising
a series of orifices extending through said orifice plate,
a first pattern of first flow chambers formed in one of said flow chamber plates, and
a second pattern of second flow chambers formed in the other of said flow chamber plates,
said first and second patterns of flow chambers aligned relative to each other
and relative to said series of orifices such that the tortuous flow path extends
from an initial one of the flow chambers to a final one of the flow chambers, alternating
between the first and second flow chambers and passing through one of said orifices
each time the tortuous flow path enters or leaves one of the first and second flow
chambers.
13. The fluid flow distribution device of claim 12 wherein said first and second
flow chambers of each of the tortuous flow path units are open to both sides of
the corresponding flow chamber plate and are enclosed by said orifice plate on
one side of each of the flow chamber plates and by respective end plates on the
opposite sides of the flow chamber plates.
14. The fluid flow distribution device of claim 13 wherein:
one of said end plates has an inlet opening connected to said fluid inlet and
aligned with an initial one of said first and second flow chambers to direct the
fluid flow from the fluid inlet to the tortuous flow path; and
one of said end plates has an outlet opening aligned with a final one of said
first and second flow chambers and connected to at least one of said heat exchange
units to direct the fluid flow from the tortuous flow path to said at least one
of said heat exchange units.
15. The fluid flow distribution device of claim 14 wherein said inlet and outlet
openings are not in the same end plate.
16. The fluid flow distribution device of claim 15 further comprising a pair
of flow manifold plates, and wherein the plurality of tortuous flow path units
are sandwiched between the flow manifold plates, one of said flow manifold plates
including a flow path channel aligned with the fluid inlet and each of the inlet
openings in each of the tortuous flow path units to direct the fluid flow from
the fluid inlet to each of the inlet openings, the other of the flow manifold plates
including a plurality of discrete flow path channels, each of said discrete flow
path channels aligned with one of said outlet openings and the associated at least
one of said exchange units to direct the fluid flow from the one of said outlet
openings to the associated at least one of said heat exchange units.
17. The fluid flow distribution device of claim 16 further comprising:
an inlet plate overlaying said one of said flow manifold plates and including
an inlet port therein aligned with said fluid inlet and said flow path channel; and
a header plate overlaying said other of said flow manifold plates and including
a plurality of openings, each opening receiving one of said heat exchange units
and aligned with one of said discrete flow channels.
18. The fluid flow distribution device of claim 12 wherein:
the series of orifices of all of the tortuous flow path units are located in
a single orifice plate;
the first patterns of all of said plurality of tortuous flow path units are located
in a single flow chamber plate; and
the second patterns of all of said plurality of tortuous flow path units are
located in a single flow chamber plate.
19. The fluid flow distribution device of claim 12 wherein said first and second
flow chambers all have the same shape and size.
20. The fluid flow distribution device of claim 19 wherein said first and second
flow chambers are hexagonal shaped.
21. The fluid flow distribution device of claim 19 wherein said first and second
flow chamber plates are identical in construction.
22. The fluid flow distribution device of claim 19 wherein said series of orifices
are arranged in a serpentine pattern.
23. A fluid flow distribution device for use in a heat exchange er having multiple
heat exchange units that receive a fluid flow from a fluid inlet; the device comprising:
a pair of end plates;
a pair of flow chamber plates sandwiched between the end plates;
an orifice plate sandwiched between the flow chamber plates; and
a plurality of tortuous flow paths to direct the fluid flow from the inlet to
the heat exchange units, the tortuous flow paths defined by the orifice plate and
the flow chamber plates sandwiched between the end plates, each of the tortuous
flow paths comprising
a series of orifices extending through said orifice plate,
a first pattern of first flow chambers formed in one of said flow chamber plates, and
a second pattern of second flow chambers formed in the other of said flow chamber plates,
said first and second patterns of flow chambers aligned relative to each other
and relative to said series of orifices such that the tortuous flow path extends
from an initial one of the flow chambers to a final one of the flow chambers, alternating
between the first and second flow chambers and passing through one of said orifices
each time the tortuous flow path enters or leaves one of the first and second flow
chambers.
24. The fluid flow distribution device of claim 23 wherein said first and second
flow chambers of each of the tortuous flow path units are open to both sides of
the corresponding flow chamber plate and are enclosed by said orifice plate on
one side of each of the flow chamber plates and by the end plates on the opposite
side of each of the flow chamber plates.
25. The fluid flow distribution device of claim 24 wherein:
one of said end plates has a plurality of inlet openings equal in number to the
plurality of tortuous flow paths, each of said inlet openings connected to said
fluid inlet and aligned with an initial one of said first and second flow chambers
of one of the tortuous flow paths to direct the fluid flow from the fluid inlet
to the tortuous flow path; and
one of said end plates has a plurality of outlet openings equal in number to
the plurality of tortuous flow paths, each of said outlet opening aligned with
a final one of said first and second flow chambers of one of said tortuous flow
paths and connected to at least one of said heat exchange units to direct the fluid
flow from the tortuous flow path to said at least one of said heat exchange units.
26. The fluid flow distribution device of claim 25 wherein said inlet and outlet
openings are not in the same end plate.
27. The fluid flow distribution device of claim 26 further comprising a pair
of flow manifold plates, and wherein the end plates sandwiched between the flow
manifold plates, one of said flow manifold plates including a flow path channel
aligned with the fluid inlet and each of the inlet openings to direct the fluid
flow from the fluid inlet to each of the inlet openings, the other of the flow
manifold plates including a plurality of discrete flow path channels, each of said
discrete flow path channels aligned with one of said outlet openings and the corresponding
at least one of said exchange units to direct the fluid flow from the outlet opening
to the corresponding at least one of said heat exchange units.
28. The fluid flow distribution device of claim 27 further comprising:
an inlet plate overlaying said one of said flow manifold plates and including
an inlet port therein aligned with said fluid inlet and said flow path channel; and
a header plate overlaying said other of said flow manifold plates and including
a plurality of openings, each opening receiving one of said heat exchange units
and aligned with one of said discrete flow channels.
29. The fluid flow distribution device of claim 23 wherein said first and second
flow chambers all have the same shape and size.
30. The fluid flow distribution device of claim 29 wherein said first and second
flow chambers are hexagonal shaped.
31. The fluid flow distribution device of claim 29 wherein said first and second
flow chamber plates are identical in construction.
32. The fluid flow distribution device of claim 29 wherein said series of orifices
are arranged in a serpentine pattern.
Description
FIELD OF THE INVENTION
This invention relates to devices that distribute fluid flow from a common source
to a plurality of flow paths, and in more particular applications to such devices
as used in heat exchangers to equally distribute a fluid flow among a plurality
of parallel heat exchange flow paths or units for passage therethrough in heat
exchange relation with one or more other fluids.
BACKGROUND OF THE INVENTION
There are many fluid components that require a desired distribution, generally
equal, of a fluid flow among multiple flow paths from a common fluid flow source.
One example of such fluid flow components are heat exchangers, and particularly
heat exchangers that act as evaporators or vaporizers. Because the heat absorbed
by the liquid fluid that is being evaporated or vaporized is mostly latent heat,
it is typical for the majority of length of such vaporizing heat exchangers to
be occupied by a two phase fluid. Unlike some heat exchangers, for example condensers,
the flow distribution in the vaporizers is not self-correcting and different flow
conditions can produce the same pressure drop (i.e., high mass flow with low quality
change or low mass flow with super heat) and can therefore coexist in parallel
flow paths. This can result in heat fluxes that vary significantly from flow path
to flow path (i.e., from tube to tube) and can negatively affect performance and
stability in the vaporizer.
One very specific example of vaporizers are those that are used in the fuel processing
system for Proton Exchange Membrane (PEM) fuel cells wherein a gaseous mixture
of water vapor and hydrocarbon are chemically reformed at high temperature to produce
a hydrogen-rich flow stream commonly referred to a reformate. To produce this high
temperature water vapor and hydrocarbon stream, it is typical to either produce
steam from liquid water for the humidification of a gaseous hydrocarbon fuel, such
as methane, or to vaporize a water and liquid hydrocarbon mixture. Often, the heat
source for vaporization is a hot gas, such as the reformate or combusted anode
tail gas, which is already present in the fuel cell system and has substantial
heat available for the required vaporization of the liquid water and/or liquid
hydrocarbon. In order to make the vaporizing heat exchanger as compact as possible,
it is known to flow the fluid to be vaporized in multiple parallel flow paths or
passages in order to maximize the surface area to which the fluid is exposed within
a given volume. The multiple parallel flow paths require that the liquid phase
fluid entering the heat exchanger be distributed evenly among the parallel flow
paths. While there are vaporizers suitable for use in such systems, there is always
room for improvement. For example, some such vaporizers do not lend themselves
to be readily or easily manufactured from a variety of materials, such as out of
aluminum. One such solution has been proposed by Reinke et al in U.S. application
Ser. No. 10/145,531, filed May 14, 2002 and published as US-2003-0215679 Al which
shows a brazed stainless steel, stacked-plate type of heat exchanger. According
to this proposal, an inlet section is provided by overlapping a pair of slotted
sheets with each sheet having very narrow slots that provide a relatively high
pressure drop to each of the parallel flow path in the remainder of the heat exchanger,
which results in good distribution of the fluid flow among the parallel flow paths.
However, because larger amounts of brazing alloy would tend to clog the narrow
channels or slots in the sheets, this construction does not easily lend itself
to some materials, such as aluminum, that require a larger amount of brazing alloy
in comparison to stainless steel.
SUMMARY OF THE INVENTION
A fluid flow distribution device is provided for use in a heat exchanger having
multiple parallel flow paths or heat exchange units that receive a fluid flow from
an fluid inlet. The device includes a plurality of tortuous flow path units to
direct the fluid flow from the inlet to the heat exchange units. The units lie
in a common plane. Each tortuous flow path unit includes a pair of flow chamber
plates, an orifice plate sandwiched between the flow chamber plates, and a tortuous
flow path. Each tortuous flow path includes a series of orifices extending through
the orifice plate, a first pattern of first flow chambers formed in one of the
flow chamber plates, and a second pattern of second flow chambers formed in the
other of the flow chamber plates and offset with respect to the first pattern.
In one form of the invention, the first pattern is aligned with sequential pairs
of the orifices and the second pattern is offset with respect to the first pattern
and the pairs of orifices. Each pair of the orifices is aligned with one of the
first flow chambers and with a pair of the second flow chambers to direct the
fluid flow to the one of the first chambers from one of the pair of the second
chambers via one of the orifices of the pair of orifices and from the one of the
first chambers to the other of the pair of the second chambers via the other orifice
of the pair of orifices such that the fluid flow travels along the tortuous flow
path passing sequentially through the series of orifices while alternating between
the first and second flow chambers.
According to one form of the invention, the first and second patterns of
flow chambers are aligned relative to each other and relative to the series of
orifices such that the tortuous flow path extends from an initial one of the flow
chambers to a final one of the flow chambers, alternating between the first and
second flow chambers and passing through one of the orifices each time the tortuous
flow path enters or leaves one of the first and second flow chambers.
In one form, the first and second flow chambers of each of the tortuous flow
path
units are open to both sides of the corresponding flow chamber plate and are enclosed
by the orifice plate on one side of each of the flow chamber plates and by respective
end plates on the opposite sides of the flow chamber plates. In a further form,
one of the end plates has an inlet opening connected to the fluid inlet and aligned
with an initial one of the first and second flow chambers to direct the fluid flow
from the fluid inlet to the tortuous flow path; and one of the end plates has an
outlet opening aligned with a final one of the first and second flow chambers and
connected to at least one of the heat exchange units to direct the fluid flow from
the tortuous flow path to the at least one of the heat exchange units. In yet
a further form, the inlet and outlet openings are not in the same end plate. In
one form, the fluid flow distribution device further includes a pair of flow manifold
plates, and the plurality of tortuous flow path units are sandwiched between the
flow manifold plates, with one of the flow manifold plates including a flow path
channel aligned with the fluid inlet and each of the inlet openings in each of
the tortuous flow path units to direct the fluid flow from the fluid inlet to each
of the inlet openings, and the other of the flow manifold plates including a plurality
of discrete flow path channels, each of the discrete flow path channels aligned
with one of the outlet openings and the associated at least one of the exchange
units to direct the fluid flow from the one of the outlet openings to the associated
at least one of the heat exchange units. In a further form, the fluid flow distribution
device further includes an inlet plate overlaying the one of the flow manifold
plates and including an inlet port therein aligned with the fluid inlet and the
flow path channel, and a header plate overlaying the other of the flow manifold
plates and including a plurality of openings, each opening receiving one of the
heat exchange units and aligned with one of the discrete flow channels.
In one form of the invention, the series of orifices of all of the tortuous flow
path units are located in a single orifice plate, the first patterns of all of
the plurality of tortuous flow path units are located in a single flow chamber
plate; and the second patterns of all of the plurality of tortuous flow path units
are located in a single flow chamber plate.
In accordance with one form of the invention, a fluid flow distribution device
is provided for use in a heat exchanger having multiple heat exchange units that
receive a fluid flow from an fluid inlet. The device includes a pair of end plates,
a pair of flow chamber plates sandwiched between the end plates, an orifice plate
sandwiched between the flow chamber plates, and a plurality of tortuous flow paths
defined by the orifice plate and the flow chamber plates sandwiched between the
end plates. Each of the tortuous flow paths includes a series of orifices extending
through the orifice plate, a first pattern of first flow chambers formed in one
of the flow chamber plates, and a second pattern of second flow chambers formed
in the other of the flow chamber plates. The first and second patterns of flow
chambers are aligned relative to each other and relative to the series of orifices
such that the tortuous flow path extends from an initial one of the flow chambers
to a final one of the flow chambers, alternating between the first and second flow
chambers and passing through one of the orifices each time the tortuous flow path
enters or leaves one of the first and second flow chambers.
In one form, the first and second flow chambers of each of the tortuous flow
path
units are open to both sides of their respective flow chamber plate and are enclosed
by the orifice plate on one side of each of the flow chamber plates and by the
end plates on the opposite side of each of the flow chamber plates. In a further
form, one of the end plates has a plurality of inlet openings equal in number to
the plurality of tortuous flow paths, with each of the inlet openings connected
to the fluid inlet and aligned with an initial one of the first and second flow
chambers of one of the tortuous flow paths to direct the fluid flow from the fluid
inlet to the tortuous flow path, and one of the end plates has a plurality of outlet
openings equal in number to the plurality of tortuous flow paths, with each of
the outlet opening aligned with a final one of the first and second flow chambers
of one of the tortuous flow paths and connected to at least one of the heat exchange
units to direct the fluid flow from the tortuous flow path to the at least one
of the heat exchange units. In yet a further form, the inlet and outlet opening
are not in the same end plate. In one form, the fluid flow distribution device
further includes a pair of flow manifold plates, the end plates are sandwiched
between the flow manifold plates, one of the flow manifold plates includes a flow
path channel aligned with the fluid inlet and each of the inlet openings to direct
the fluid flow from the fluid inlet to each of the inlet openings, and the other
of the flow manifold plates includes a plurality of discrete flow path channels,
with each of the discrete flow path channels being aligned with one of the outlet
openings and the corresponding at least one of the exchange units to direct the
fluid flow from the outlet opening to the corresponding at least one of the heat
exchange units. In a further form, the fluid flow distribution device further includes
an inlet plate overlaying the one of the flow manifold plates and including an
inlet port therein aligned with the fluid inlet and the flow path channel, and
a header plate overlaying the other of the flow manifold plates and including a
plurality of openings, with each opening receiving one of the heat exchange units
and being aligned with one of the discrete flow channels.
According to one form of the invention, the first and second flow chambers
all have the same shape and size. In a further form, the first and second flow
chambers are hexagonal shaped.
In one form, the first and second flow chamber plates are identical in construction.
In accordance with one form of the invention, the series of orifices are arranged
in a serpentine pattern.
Other objects, advantages, and features of the invention will be understood
from a complete reading of the entire specification, including the appended drawings,
claims and abstract.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing a fluid flow distribution device embodying
the present invention;
FIG. 2 is an exploded view of the fluid distribution device of FIG. 1;
FIG. 3 is an exploded view showing portions of several selected components from
FIG. 2;
FIG. 4 is a somewhat diagrammatic view taken from line 4—4
in FIG. 3; and
FIG. 5 is a graph illustrating the pressure drop versus mass flow characteristics
for the device of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to FIG. 1, a fluid flow distribution device
10 is shown
in connection with a heat exchanger
12 having multiple parallel heat exchange
flow paths or units
14 shown in the form of extruded, flattened multiport
tubes (shown in phantom with only partial lengths). The heat exchanger
12
further includes a fluid inlet
16 (shown in phantom) that receives a fluid
flow
18 that should, under ideal conditions, be equally distributed among
the plurality of heat exchange units
14. The distributed fluid flow
18
passes through the interior ports of the tubes
14 for the transfer of heat
to another fluid flow that is in heat exchange relation with the exterior of the
tubes
14, typically through some suitable type of fin (not shown), such
as serpentine fins extending between adjacent tubes or plate fins extending across
all of the tubes
14. A collection manifold (not shown) for the fluid flow
18 will normally be provided on the opposite end of the heat exchange units
14 to collect the distributed fluid flow
18 from the heat exchange
units
14.
It should be appreciated that while the fluid flow distribution device
10
is shown herein in connection with heat exchange flow paths or units
14
shown in the form of extruded multiport tubes, the fluid flow distribution device
according to the invention will find use with any other suitable form of heat exchanger
or heat exchange flow path or unit, many of which are known, such as for example,
welded tubes, drawn cup or stacked-plate type constructions, and/or bar-plate type
constructions. Furthermore, while the construction illustrated in FIG. 1 is shown
in connection with five heat exchange units
14, the fluid flow distribution
device
10 according to the invention can find use in heat exchangers having
two or more heat exchange flow paths or units that require the fluid flow to be
distributed therebetween. Accordingly, no limitation is intended to a particular
type of heat exchange flow path or unit or to a specific number of such flow paths
or units, unless expressly recited in the claims.
The fluid flow distribution device
10 of FIG. 1 is illustrated in the
form of a stacked, brazed plate construction, which is shown exploded in FIG. 2.
The flow distribution device
10 includes a pair of end plates
20,
22,
a pair of flow chamber plates
24,
26 sandwiched between the end plates
20,
22, and an orifice plate
28 sandwiched between the flow
chamber plates
24,
26. Together the plates
20,
22,
24,
26, and
28 form a multiple tortuous flow path component
30
having a sandwiched, plate type construction and defining a plurality of tortuous
flow paths, illustrated very schematically in FIG. 2 by dashed arrow lines
31,
with each flow path
31 corresponding to one of the tubes
14 and extending
from an inlet opening
32 in the end plate
20 to an outlet opening
33 in the end plate
22. Each of the tortuous flow paths
31
includes a series
34 of orifices
36 extending through the orifice
plate
28, a first pattern
38 of flow chambers
40 formed in
the flow chamber plate
24, and a second pattern
42 of second flow
chambers
44 formed in the other flow chamber plate
26. As will be
explained in more detail below, for each of the tortuous flow paths
31,
the first and second patterns
38 and
42 of first and second flow
chambers
40 and
44 are aligned relative to each other and with the
series
34 of orifices
36 so that the tortuous flow path
31
passes in an alternating fashion between the first and second flow chambers
40,
44
and sequentially through the orifices
36, passing through one of the orifices
36 each time the tortuous flow path
31 enters or leaves one of the
first and second flow chambers
40 and
44.
The illustrated embodiment of the flow distribution device
10 in FIG.
2 further includes a pair of flow manifold plates
46 and
48, with
the tortuous flow path component
30 sandwiched therebetween, an inlet plate
50 overlaying the flow manifold plate
36 and including an inlet port
60 of the fluid inlet
16 extending therethrough, and a header plate
62 overlaying the other manifold plate
48 and including a plurality
of openings
64 in the form of slots, with each opening
64 receiving
one of the heat exchanger units
14. The flow manifold plate
46 includes
a flow path channel
66 in the form of a multi-legged slot extending through
the plate
46. The channel
66 includes a leg portion
68 that
extends from a manifold portion
70 to align with the inlet port
60
to direct the fluid flow from the inlet port
60 to the manifold portion
70, and a plurality of additional leg portions
72, with each portion
72 extending from the manifold portion
70 into alignment with one
of the inlet openings
32 in the end plate
20 to direct a distributed
portion of the fluid flow
18 thereto. The manifold plate
48 includes
a plurality of discrete flow path channels
74 in the form of legged slots
extending therethrough; with each of the channels
74 including a leg portion
76 aligned with one of the outlet openings
33 and extending from
an elongate portion
78 aligned with one of the openings
64 to transfer
a distributed portion of the fluid flow
18 from the outlet opening
33
to the opening
64.
With reference to FIG. 3, the components that make up one of the tortuous flow
paths
32 (again shown very schematically by the dashed arrowed line in FIG.
3) are shown enlarged and broken away from the other tortuous flow path
32.
In this regard, it should be noted that the portions of the plates
20,
22,
24,
26,
28
shown in FIG. 3 can be considered to form individual tortuous flow path units
80,
with each of the portions shown in FIG. 3 being part of a common plate such as
shown in FIG. 2, or, alternatively, formed as individual components, such as shown
in FIG. 3, that lie in a common plane with other individual tortuous flow path
units
80 constructed from similar individual components to define additional
tortuous flow paths
32. As seen in FIG. 3, each of the flow chambers
40,
44
have an identical hexagonal shape defined by uniformly thin webs
82,
84
that extend between the flow chambers
40,
44, respectively, to define
the respective first and second patterns
38,
42. In this regard, it
should be noted that in the illustrated embodiment, the patterns
38 and
42 are identical, but are flipped 180° about an axis
86 relative
to each other so as to offset the patterns
38 and
42 relative to
each other in the assembled state. The series
34 of orifices
36 is
provided in a serpentine shape or pattern so as to provide the desired alignment,
best seen in FIG. 4, with each of the flow chambers
40,
44 in the
respective patterns
38,
42. More specifically, sequential pairs (identified
in FIG. 4 as orifices
36A and
36B in each pair) of the orifices
36
are aligned with each of the first flow chambers
40 and with a pair of the
second flow chambers
44.
The tortuous flow path
31 is best understood in connection with FIG. 4,
which shows the tortuous flow path
31 in the form of solid arrows and dashed
arrows, with the solid arrows representing flow through the flow chambers
44
of the second pattern
42 and the dashed arrows representing flow through
the flow chambers
40 of the first pattern
38 (shown solid in FIG.
4 for purposes of illustration). In the embodiment shown in FIG. 4, the tortuous
flow path extends from an initial one
44A of the flow chambers
44
to a final one
40A of the flow chambers
40, alternating between
the first and second flow chambers
40,
44 while passing sequentially
through the orifices
36. More specifically, the tortuous flow path
31
enters the initial flow chamber
40A via the inlet opening
32 (shown
in phantom for purposes of illustration), flows through the flow chamber
44A
to a first one of the orifices
36A, passes through the orifice
36A
into one of the flow chambers
40, flows through the one of the flow chambers
40 to another one of the orifices
36B (the other orifice of the pair
of orifices associated with the one of the flow chambers
40), passes through
the orifice
36B into another one of the flow chambers
44, and so
on and so on, passing through one of the orifices
36 each time the tortuous
flow path
31 enters or leaves one of the flow chambers
40,
44
until the tortuous flow path enters the final flow chamber
40A and exits
the tortuous flow path unit
80 via the outlet opening
33. To state
this in other terms, the flow chambers
40,
44 provide a flow paths
between each of the orifices
36 of the series
34 so that the fluid
flows in a sequential manner through the orifices
36 of the tortuous flow
path
31.
The liquid pressure drop in each of the tortuous flow paths
31 is accomplished
by a velocity head loss and a contraction and expansion head loss at each of the
orifices
36, as opposed to a frictional loss by flowing through a relatively
long, small area flow channel as in some previously proposed designs, such as the
Reinke et al application discussed in the Background section. The pressure drop
through each of the tortuous flow paths
31 can be adjusted by varying the
size and number of orifices
36 in the series
34.
While any suitable material and joining method can be used, preferably, each
of the plates
20,
22,
24,
26,
28,
46,
48,
50,
62
are made of aluminum and are stacked and brazed together. It is also preferred
that the orifice plate
28 be an unclad plate and that each of the flow chamber
plates
24,
26 be clad with brazing alloy on both sides. Each of the
end plates
20,
22 is preferably unclad on the side that faces the
respective flow chamber plate
24,
26, but may optionally be clad
with brazing alloy on the opposite side so as to form a brazed joint with the corresponding
manifold plate
46,
48. Alternatively, each of the end plates
20,
22
can be unclad on both sides, with each of the manifold plates
46,
48
being clad with brazing alloy on both of their sides so as to form brazed joints
with the corresponding end plates
20,
22 and corresponding inlet plate
58 or header plate
62. It should be appreciated that because the
first and second patterns
38,
42 of flow chambers
40,
44
provide a large percentage of open area with uniformly thin webs
82,
84
that face the orifice plate
28, the concerns for clogging each of the tortuous
flow paths
31 with braze are minimized. This is particularly true because
the design reduces the amount of braze alloy that is located close to each of the
orifices
36 in the orifice plate
28. To state this in other terms,
because the face area of each of the flow chamber plates
24,
26 has
been greatly reduced by the first and second patterns
38,
42 of flow
chambers
40,
44, and the braze alloy used to join the plates
24,
26
to the orifice plate
28 is found only on the faces of the flow chamber plates
24,
26, the amount of braze alloy present for clogging each of the
tortuous flow paths
31, and in particular the orifice holes
36, has
been greatly reduced. In this regard, controlled brazed atmosphere trials were
performed on the patterns shown in FIG. 4 to produce five test pieces with five
different diameters for the orifice holes
36 ranging from 0.031 inch to
0.052 inch. In all cases, the brazing was successful and the orifice holes
36
remained open.
FIG. 5 illustrates the results of mass flow versus pressure drop testing using
liquid water performed on each of the above-referenced test pieces, with the test
results shown in comparison to the predicted performance accordance to calculations
(predicted performance shown by solid lines, test results shown by dashed lines).
The predicted pressure drop in (PSI) versus mass flow rate in (grams/sec) was calculated
as consisting of two velocity head losses for each of the orifices
36, with
the first being a full velocity head loss for the flow in the plane of the plates
24,
26,
28 and the second velocity head loss being the full
head loss for the flow through each of the orifices
36. The flow area for
the first head loss was approximated to be the surface of a cylinder having a diameter
equal to the diameter of the orifices
36 and a height equal to the thickness
of one of the flow chamber plates
24,
26. The first head loss was
then calculated as m
2/(2ρA
12), where m is
the mass flow rate, p is the density of water and A
1 is the calculated
flow area. The second head loss was calculated as m
2/(2ρA
22),
where A
2 is the area of a circle with a diameter equal to the diameter
of the orifice
36. The total predicted pressure drop was calculated as the
sum of these two head losses multiplied by the number of orifices
36 in
the series
34 and then corrected with a loss coefficient of 20. Each of
the test pieces was tested by forcing water at various inlet pressures through
the test piece with the outlet opening
33 being at atmospheric pressure.
The water passing through the test piece was collected for a fixed time duration
and was weighed to determine the mass flow rate at that pressure. As seen in FIG.
5, there is a good correlation between the test results and the predicted values
when a loss coefficient of two was applied to the predicted values. As also seen
in FIG. 5, the design works well over a range of flow velocities, including low
flow velocities.
With reference to FIG. 2, in a highly preferred construction, the plates
24,
26
are identical to each other and are simply rotated 180° about their longitudinal
axes with respect to each other before they are brazed to the orifice plate
28.
This results in the same face of the identical flow chamber plates
24,
26
being brazed against the corresponding face of the orifice plate
28. Similarly,
the end plates
20,
22 are identical in construction and are rotated
180° about their longitudinal axes with respect to each other so that the
same face of each plate
20,
22 is brazed to the corresponding face
of the corresponding flow chamber plate
24,
26. To achieve this orientation
during assembly, an upper corner of each of the plates
20,
22,
24,
26
is chamfered and then aligned with similar chamfers on each of the opposite upper
corners of the orifice plate
28. Similar chamfers are provided on the plates
46,
48,
50,
62 so that in the assembled state, you have
aligned chamfers
90 and
92 for each half of the fluid flow distribution
device, thereby assuring proper assembly of the device
10.
It should be appreciated that while hexagonal shaped flow chambers
40,
44
are shown, other shapes, such as, for example, circles, rectangles, squares, ovals,
triangles, trapezoids, octagons, etc., may be used for forming the first and second
patterns
38,
42. Similarly, while it is preferred for the patterns
38,
42 to be identical with identically shaped flow chambers
40,
44,
in some applications it may be desirable for the patterns
38,
42 to
be different while utilizing the same shape flow chambers
40,
44 or
while utilizing different shaped flow chambers
40,
44. Additionally,
it should be appreciated that while the inlet and outlet openings
31,
33
are shown in FIGS. 3 and 4 as being located in one of the end plates
20,
22
or the other, in some applications it may be desirable for the inlet and outlet
openings
31,
33 to be located in the same end plate
20,
22
which would result in the initial and final flow chambers of the tortuous flow
path
31 being located in the same flow chamber pattern
38 or
42,
as opposed to having the initial flow chamber
40 or
44 being located
in one of the patterns
38,
42, and the final flow chamber
40
or
44 being located in the other flow pattern
38,
42.
It has been found that by providing a relatively high pressure drop in the inlet
region of each of a plurality of parallel heat exchange flow paths or units, good
distribution of a fluid flow can be achieved among the parallel heat exchange flow
paths or units. It should be appreciated that fluid flow distribution devices according
to the invention can provide this benefit in a structure that can reduce the potential
for clogging in comparison to other proposed designs.
*
