U.S. patent application number 15/666383 was filed with the patent office on 2018-01-25 for bi-directional fill for use in cooling towers.
The applicant listed for this patent is Evapco, Inc.. Invention is credited to Thomas W. Bugler, Sarah L. Ferrari, John W. Lane, Jean-Pierre Libert, Davey J. Vadder.
Application Number | 20180023905 15/666383 |
Document ID | / |
Family ID | 60988240 |
Filed Date | 2018-01-25 |
United States Patent
Application |
20180023905 |
Kind Code |
A1 |
Vadder; Davey J. ; et
al. |
January 25, 2018 |
BI-DIRECTIONAL FILL FOR USE IN COOLING TOWERS
Abstract
Cooling towers and cooling tower fill configured for the cooling
of process water with air by indirect heat exchange, in which the
fill is configured with a first set of channels and a second set of
channels, said first and second set of channels interleaved with
one-another so that heat exchange occurs across material separating
said channels from one-another.
Inventors: |
Vadder; Davey J.;
(Manchester, MD) ; Ferrari; Sarah L.; (Mount Airy,
MD) ; Lane; John W.; (Finksburg, MD) ; Libert;
Jean-Pierre; (Frederick, MD) ; Bugler; Thomas W.;
(Middletown, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Evapco, Inc. |
Taneytown |
MD |
US |
|
|
Family ID: |
60988240 |
Appl. No.: |
15/666383 |
Filed: |
August 1, 2017 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14757640 |
Dec 23, 2015 |
9719726 |
|
|
15666383 |
|
|
|
|
62096194 |
Dec 23, 2014 |
|
|
|
62148969 |
Apr 17, 2015 |
|
|
|
Current U.S.
Class: |
165/96 |
Current CPC
Class: |
F28F 25/10 20130101;
F28F 25/087 20130101; F28F 25/08 20130101; F28C 2001/006 20130101;
F28C 2001/145 20130101; F28D 3/00 20130101; F28C 1/14 20130101 |
International
Class: |
F28F 25/08 20060101
F28F025/08; F28F 25/10 20060101 F28F025/10; F28D 3/00 20060101
F28D003/00 |
Claims
1. A cooling tower comprising cooling tower fill arranged for the
cooling of process water with air by indirect heat exchange, in
which the fill is configured with a first set of channels and a
second set of channels, said first and second set of channels
interleaved with one-another so that heat exchange occurs across
material separating said channels from one-another.
2. A cooling tower according to claim 1, comprising a first set of
spray heads configured to direct said process water only to said
first set of channels, and a second set of spray heads configured
to direct said process water only to said second set of channels or
to all channels.
3. A cooling tower according to claim 1, configured to allow heat
exchange between process water in said first set of channels and
air in said second set of channels when said first set of spray
heads is open, permitting process water to flow through said first
set of channels, and said second set of spray heads is closed.
4. (canceled)
5. (canceled)
6. A cooling tower according to claim 1 in which said channels are
created by one or more fill packs, each fill pack comprising layers
of stacked corrugated sheets, each corrugated sheet having a
longitudinal axis that is shifted 30.degree. to 90.degree. relative
to a longitudinal axis of adjacent corrugated sheets, each
corrugated sheet separated from an adjacent corrugated sheet by an
intermediate sheet.
7. A cooling tower according to claim 1, wherein said corrugated
sheets are bonded to adjacent intermediate sheets along corrugation
ridges of said corrugated sheets.
8. A cooling tower according to claim 6, wherein said first set of
channels are oriented at an angle of 45.degree. relative to
vertical, and where said second set of channels are also oriented
at an angle of 45.degree. relative to vertical, but perpendicular
to said first set of channels.
9. A cooling tower according to claim 6, wherein said fill packs
have a length and a width that are approximately equal.
10. A cooling tower according to claim 6, wherein said fill packs
have a length and a width, and wherein the length of said fill
packs is 1 to 3 times the width.
11. A cooling tower according to claim 6, wherein said fill packs
are arranged in a plurality of layers across said cooling
tower,
12. A cooling tower according to claim 6 comprising open areas
between said fill packs.
13. (canceled)
14. A cooling tower according to claim 6, wherein said each of said
fill packs comprise stacked corrugated and intermediate sheets that
extend across a plurality of indirect heat exchange zones of said
cooling tower.
15. (canceled)
16. A cooling tower according to claim 6, comprising a plurality of
fill packs stacked on top of one-another in said cooling tower, and
wherein each said fill pack is oriented 180.degree., horizontally,
relative to a fill pack immediately above and/or below.
17. A cooling tower according to claim 1, wherein said first and
second sets of channels have the same dimensions.
18. A cooling tower according to claim 1, wherein said first set of
channels is larger in cross-section than said second set of
channels.
19. A cooling tower fill pack comprising a stack of identical
plastic sheets, each sheet having a first face and a second face,
said first face having a first set of ridges that define a first
set of channels, said second face having a second set of ridges
that define a second set of channels, and wherein in said fill
pack, said plastic sheets are stacked so that a first face of a
first sheet, is mated with a first face of a second sheet, turned
upside down, and a second face of said second sheet is mated with a
second face of a third sheet, turned upside down relative to said
second sheet.
20. A cooling tower fill pack according to claim 19, wherein said
plastic sheets comprise crenellated portions where at top and
bottom sections where said channel-defining-ridges terminate.
21. A cooling tower fill pack comprising a stack of two different
plastic sheets, each sheet having a first face and a second face,
said first face having a first set of ridges that define a first
set of channels, said second face having a second set of ridges
that define a second set of channels, and wherein in said fill
pack, said plastic sheets are stacked so that a first face of a
first sheet, is mated with a first face of a second sheet, and a
second face of said second sheet is mated with a second face of a
third sheet identical to the first sheet to form two sets of
channels, said first and second sets of channels interleaved with
one-another so that heat exchange occurs across material separating
said channels from one-another.
22. A cooling tower according to claim 5, wherein said channels
define an odd number of input zones and one fewer columns than
input zones.
23. A cooling tower according to claim 22, wherein outermost
channels are water channels.
24. A cooling tower according to claim 22, wherein said input zones
have an equal width, and wherein said columns are of unequal
width.
25. A cooling tower according to claim 22, wherein the columns are
all the same width and outermost input zones have a width that is
1/2 a width of interior input zones.
26. A cooling tower according to claim 22, wherein the columns are
all the same width and the input zones have unequal width.
27. A cooling tower according to claim 1 in which said channels are
created by one or more fill packs, each fill pack comprising layers
of stacked corrugated sheets, each corrugated sheet having formed
thereon at water input zones a plurality of convex ridges and
impressions, each ridge corresponding to an impression on an
opposite side of a fill sheet on which said ridge is formed; said
ridges arranged to direct water that falls in a input zone in which
the ridges are formed to move laterally into a corresponding water
column.
28. A cooling tower according to claim 1, further comprising
adjustable air dampers positioned above water input regions of said
fill or below the water exit regions of said fill to restrict the
amount of air that passes through water columns of said fill.
29. A cooling tower according to claim 28, wherein said adjustable
air dampers are automatically controlled in combination with an
automatically controlled variable speed fan.
Description
FIELD OF THE INVENTION
[0001] This invention relates to the use of bi-directional fill in
cooling towers and methods of manufacturing fill.
SUMMARY OF THE INVENTION
[0002] There is provided according to an embodiment of the
invention, a cooling tower including cooling tower fill arranged
for the cooling of process water with air by indirect heat
exchange, in which the fill is configured with a first set of
channels and a second set of channels, said first and second set of
channels interleaved with one-another so that heat exchange occurs
across material separating said channels from one-another.
[0003] According to a further embodiment of the invention, a first
set of spray heads is configured to direct said process water only
to said first set of channels, and a second set of spray heads is
configured to direct said process water only to said second set of
channels or to both sets of channels.
[0004] According to a further embodiment of the invention, the
cooling tower is configured to allow indirect heat exchange between
process water in said first set of channels and air in said second
set of channels when said first set of spray heads is open,
permitting process water to flow through said first set of
channels, and said second set of spray heads is closed.
[0005] According to a further embodiment of the invention, said
first set of channels are vertical from a top of said fill to a
bottom of said fill, and wherein said second set of channels shift
one column width at a top section of said fill, are vertical
through a middle section of said fill, and optionally shift back
one column width at a bottom section of said fill.
[0006] According to a further embodiment of the invention, said
first set of channels shift one-half column width in a first
direction at a top section of said fill, are vertical through a
middle section of said fill, and optionally shift back one-half
column width at a bottom section of said fill, and said second set
of channels shift one-half column width in a second direction at
said top section of said fill, are vertical through a middle
section of said fill, and optionally shift back one-half column
width at said bottom section of said fill.
[0007] According to a further embodiment of the invention, said
channels are created by one or more fill packs, each made up of
layers of stacked corrugated sheets, each corrugated sheet having a
longitudinal axis that is shifted 30.degree. to 90.degree. relative
to a longitudinal axis of adjacent corrugated sheets, each
corrugated sheet separated from an adjacent corrugated sheet by an
intermediate sheet.
[0008] According to a further embodiment of the invention, said
corrugated sheets are bonded to adjacent intermediate sheets along
corrugation ridges of said corrugated sheets.
[0009] According to a further embodiment of the invention, said
first set of channels are oriented at an angle of 45.degree.
relative to vertical, and said second set of channels are also
oriented at an angle of 45.degree. relative to vertical, but
perpendicular to said first set of channels.
[0010] According to a further embodiment of the invention, said
fill packs have a length and width that are approximately
equal.
[0011] According to a further embodiment of the invention, said
fill packs have a length and a width, and wherein the length of
said fill packs is 1.5 to 3 times the width.
[0012] According to a further embodiment of the invention, said
fill packs are arranged in a plurality of layers across said
cooling tower,
[0013] According to a further embodiment of the invention, there
are open areas between said fill packs.
[0014] According to a further embodiment of the invention,
omnidirectional fill is arranged in the spaces between said fill
packs.
[0015] According to a further embodiment of the invention, each of
said stacked corrugated and intermediate sheets of said fill packs
extend across a plurality of indirect heat exchange zones of said
cooling tower.
[0016] According to a further embodiment of the invention, internal
intermediate sheets have beveled corners to allow fluid or air
communication to isolated areas of said fill pack.
[0017] According to a further embodiment of the invention, a
plurality of fill packs may be stacked on top of one-another in
said cooling tower, and each said fill pack may be oriented
180.degree., horizontally, relative to a fill pack immediately
above and/or below.
[0018] According to a further embodiment of the invention, said
first and second sets of channels have the same dimensions.
[0019] According to a further embodiment of the invention, said
first set of channels is larger in cross-section than said second
set of channels.
[0020] According to a further embodiment of the invention, there is
provided a cooling tower fill pack having a stack of identical
plastic sheets, each sheet having a first face and a second face,
said first face having a first set of ridges that define a first
set of channels, said second face having a second set of ridges
that define a second set of channels, and wherein in said fill
pack, said plastic sheets are stacked so that a first face of a
first sheet, is mated with a first face of a second sheet, turned
upside down, and a second face of said second sheet is mated with a
second face of a third sheet, turned upside down relative to said
second sheet.
[0021] According to a further embodiment of the invention, said
plastic sheets comprise crenellated portions where at top and
bottom sections where said channel-defining-ridges terminate.
DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a perspective representation of a bi-directional
fill pack which may be used according to the invention.
[0023] FIG. 2A is an elevational view of a cooling tower fill
section including bi-directional fill packs according to the
invention, showing three layers of fill packs arranged in a diamond
configuration.
[0024] FIG. 2B is a partially exploded view of a single fill pack
of FIG. 2A in the diamond configuration.
[0025] FIG. 3A is a representation of the cooling tower fill
section of FIG. 2, showing the flow of water when only the A set of
spray heads are providing water.
[0026] FIG. 3B is a representation of the cooling tower fill
section of FIG. 2, showing the flow of air when only the A set of
spray heads are providing water, and the fan is drawing air up
through the fill section in a counterflow configuration.
[0027] FIG. 3C illustrates how an embodiment of the invention can
be applied to a crossflow cooling tower.
[0028] FIG. 4 is an elevational view of a cooling tower fill
section including bi-directional fill packs according to a further
embodiment of the invention, in which the fill packs are elongated
in one dimension, showing two layers of fill packs arranged in a
diamond configuration.
[0029] FIG. 5 is an elevational view of a cooling tower fill
section including bi-directional fill packs as in FIG. 2, but in
which the open areas of FIG. 2 contain omnidirectional fill.
[0030] FIG. 6 is an elevational view of a cooling tower fill
section two layers of bi-directional fill packs in which the fill
packs are oriented in a diamond configuration, and in which the
fill packs are made from interleaved corrugated sheets that are
arranged at 60.degree./30.degree. angles relative to
one-another.
[0031] FIG. 7A is an elevational view of a single layer of fill in
a cooling tower fill section, in which the layer of fill comprises
a single fill pack that spans the length of multiple zones.
[0032] FIG. 7B is a partially exploded view of the fill-pack shown
in FIG. 7A.
[0033] FIG. 8A is an elevational view of a single layer of fill in
a cooling tower fill section according to a different embodiment of
the invention, in which intermediate layers of intermediate sheets
are truncated at the corners to open isolated zones at the top and
bottom corners of the fill pack.
[0034] FIG. 8B is a partially exploded view of the fill-pack shown
in FIG. 8A.
[0035] FIG. 9A is a elevational view of a fill section of a cooling
tower in which the fill is comprised of three connected layers of
fill pack, each layer having the same construction of adjacent
layers, but in which each successive layer is rotated horizontally
180.degree. relative to the prior layer.
[0036] FIG. 9B is a partially exploded view of the first layer of
the fill section of FIG. 9A.
[0037] FIG. 9C is a partially exploded view of the second layer of
the fill section of
[0038] FIG. 9A.
[0039] FIG. 9D is a partially exploded view of the third layer of
the fill section of FIG. 9A.
[0040] FIG. 10 is an elevational view of a cooling tower fill
section having overlapping indirect heat exchange channels.
[0041] FIG. 11 is a representation of the three parts that may be
used to assemble the sheets which in turn may be used to construct
the fill pack shown in FIG. 10 without using a full intermediate
sheet.
[0042] FIG. 12 is a representation of a first assembled sheet that
may be used to construct the fill pack shown in FIG. 10.
[0043] FIG. 13 is a representation of a second assembled sheet that
may be used to construct the fill pack shown in FIG. 10, arranged
in an alternating/interleaved sequence with the first assembled
sheet shown in FIG. 12.
[0044] FIG. 14A is a cross sectional view along line A-A of FIG.
11.
[0045] FIG. 14B is a cross-sectional view along line A-A of FIG.
10.
[0046] FIG. 15 is a cross-sectional representation of a fill pack
similar to the fill pack shown in FIG. 10, but in which the
profiles of the sheets are modified to create different size
cross-sectional areas for the water and air flow paths.
[0047] FIG. 16 is a representation of a single sheet embodiment of
the vertical column indirect heat exchange fill pack aspect of the
invention in which single lines indicate structure, e.g., a ridge,
coming out of the plane of the sheet, double lines indicate
structure going into the plane of the sheet; and triple lines
indicate structure coming out of the plane of the sheet next to
structure going into the plane of the sheet. No intermediate sheet
is used in this embodiment.
[0048] FIG. 17 is another representation of the sheet of FIG. 16,
in which the heavy lines represent structure, e.g., ridges, coming
out of the plane of the sheet. When this face of the sheet is
paired with a second sheet of the same construction but rotated
180.degree. about the axis of symmetry, channels are formed as
indicated by the A (air) and W (water) designations.
[0049] FIG. 18 a representation of the reverse side of the sheet
shown in FIG. 17, in which the heavy lines represent structure,
e.g., ridges, coming out of the plane of the sheet. When this face
of the sheet is paired with a second sheet of the same construction
but rotated 180.degree. about the axis of symmetry, channels are
formed as indicated by the A (air) and W (water) designations.
[0050] FIG. 19 is a representation of a fill packet sheet with
straight columns and crenellated top and bottom sections to allow
for stacking.
[0051] FIG. 20 is a representation of a fill packet sheet with
indexed columns and crenellated top and bottom sections to allow
for stacking.
[0052] FIG. 21 is a representation of a fill packet sheet with
crenellated indexed channels and a four-channel repeating motif to
facilitated manufacture of longer fill packets.
[0053] FIG. 22 is a representation of a fill packet sheet with
crenellated straight channels and a four-channel repeating motif to
facilitate manufacture of longer fill packets.
[0054] FIG. 23 is representation of a first sheet for the
construction of a cooling tower fill pack having overlapping
indirect heat exchange channels, in which the columns are indexed
one-half a column width to the left.
[0055] FIG. 24 is a representation of a second sheet for the
construction of a cooling tower fill pack having overlapping
indirect heat exchange channels, in which the columns are indexed
one-half a column width to the right. Shaded portions of the figure
represent areas where there is no indirect heat exchange.
[0056] FIG. 25 illustrates how the sheet of FIG. 24 may be
thermoformed on standard equipment to make tall fill packs and
eliminating the requirement for stacking.
[0057] FIG. 26 illustrates how the sheet of FIG. 23 may be
thermoformed on standard equipment to make tall fill packs and
eliminating the requirement for stacking.
[0058] FIG. 27 is a representation of a water distribution
according to an embodiment of the present invention.
[0059] FIG. 28A illustrates an "A" sheet for a modification of the
half column-index illustrated in FIG. 23 with 5 equal input-zones
going to 4 columns, with arrows showing the water flow.
[0060] FIG. 28B illustrates a "B" sheet for a modification of the
half colum index illustrated in FIG. 24 with 5 equal input-zones
going to 4 columns, with arrows showing the water flow.
[0061] FIG. 29 illustrates a modification to the embodiment of FIG.
28B.
[0062] FIG. 30 illustrates an embodiment of the invention including
Coand{hacek over (a)}-effect spoons.
[0063] FIG. 31 illustrates another embodiment of the invention
including Coand{hacek over (a)}-effect spoons.
[0064] FIG. 32 illustrates a further embodiment of the invention
Coand{hacek over (a)}-effect spoons.
[0065] FIG. 33 illustrates an embodiment of the invention including
wet region air dampers.
DETAILED DESCRIPTION OF THE INVENTION
[0066] The present invention is an apparatus and method to reduce
water usage on an open cooling tower. Cooling towers cool water
predominately by evaporation. The present invention provides a
cooling tower that uses less water over the course of a year while
cooling to the same temperature by replacing standard fill with
bi-directional fill. The bi-directional fill provides two
interleaved and independent air-water paths through the fill. The
present invention also provides embodiments in which the fill
includes multiple vertical interleaved water and air flow paths,
allowing for concurrent or countercurrent indirect heat exchange in
the fill section of a cooling tower.
[0067] An individual bi-directional fill-pack according to a first
embodiment of the invention is illustrated in FIG. 1. The fill-pack
consists of multiple sheets of PVC arranged in a particular
pattern. Corrugated sheets of PVC are alternated with corrugations
perpendicular to each other; and thin intermediate sheets are
placed in between the corrugated sheets. In this arrangement, one
half of the corrugated sheets have corrugations that allow flow
only in a first direction, e.g. a north-south direction, while the
interleaved corrugated sheets have corrugations that allow flow
only in a perpendicular direction, e.g., an east-west
direction.
[0068] According to a further embodiment of the invention,
bi-directional fill-packs may be oriented in a cooling tower fill
section in a diamond configuration as shown in FIG. 2A, that is,
with a first set of corrugations running in a first diagonal
direction, e.g., Northwest to Southeast, and with the second,
interleaved, set of corrugations running in a second,
perpendicular, direction, e.g., Northeast to Southwest. According
to this arrangement, the cooling tower can be configured to run as
either a direct or as an indirect heat exchanger. FIG. 2B shows a
partially exploded view of the fill packs of FIG. 2A. In the
embodiment of FIG. 2A, three levels of fill packs are shown, with
five fill packs per level but fewer or more levels or fill packs
per level, may be used. According to the view shown in FIG. 2A,
each fill pack extends into the page. The fill packs may contain
five interleaved and perpendicularly arranged corrugated sheets, as
shown in FIG. 1, or they may contain fewer or many more interleaved
and perpendicularly arranged corrugated sheets. Open areas (not
containing fill) exist in the spaces between the fill packs. Spray
heads may be arranged above the fill packs to optionally direct
water into channels A and B created by the corrugations. According
to a preferred embodiment, the spray heads are divided among two
spray branches A and B, corresponding to channels A and B.
According to the embodiment shown in FIG. 2A, both sets of spray
heads A and B may provide water to the fill section, or only one or
the other set of spray heads may provide water to the fill
section.
[0069] Referring to FIG. 3A, in case of only the A spray heads
providing water, water will only flow in the A channels of the fill
packs, following the paths shown by the arrows in FIG. 3A. With
water filling the A channels as shown in FIG. 3A and spray heads B
turned off, the air drawn into the fill section by the fan will
follow the paths of least resistance, that is, through the B
Channels. Thus, referring to FIG. 3B, air flowing up from the
central bottom will predominantly flow through the B channels to
the open areas in open-area layer 1 that are labeled as `B` and
then to the four open areas in open-area layer 2 that are also
labeled with a `B`. The air will finally exit below one of the
spray branches labeled `B`. Once airflow starts out in a `B`
channel it will stay in that `B` channel until it exits the
fill-pack, never flowing through the `A` path. Due to the
arrangement of the interleaved perpendicularly oriented corrugated
sheets in the fill packs, the `A` and `B` paths are completely
separate paths through the fill pack.
[0070] According to the arrangement shown in FIG. 2A, then, the
cooling tower can be run in 3 different configurations.
[0071] According to a first configuration, if the water is allowed
to flow equally through both spray branches, the tower will act as
a standard counterflow direct-cooling cooling tower. Water will
flow down through both A and B channels, and air will flow up
through both A and B channels, drawn by the fan. The airflow and
water flow in each of the channels will be equal.
[0072] According to a second configuration, when the ambient dry
bulb is cool, the tower may be run in an indirect cooling mode. In
the indirect cooling mode, all of the water may be caused to flow
through channel `A` channels, and no water will flow through
channel `B` channels. In this mode there is double the design water
flow going through `A` channels which increases the resistance of
air trying to flow up channel `A` channels. With no water flowing
through `B` channels, the resistance of air trying to flow up `B`
channels will be reduced. The result of this water flow arrangement
is that more of the air will now flow in the dry channels with less
flowing in the flooded channels.
[0073] Since the A and B channels are interleaved, the open cooling
tower will now be mostly an indirect heat exchanger, as the warm
water flowing down the `A` channels will be cooled by the cool air
flowing up the `B`channels. While there will still be some
evaporation occurring in the `A` channels, as not all of the air
will be directed to the `B` channels, there will be significantly
less evaporation than with a standard tower.
[0074] According to a third configuration, when the ambient
dry-bulb is too high to allow operation in the fully indirect mode,
a partially indirect mode may be used. In this third configuration
some water would be directed to the `B` channels via the B spray
heads. By sending some water through the `B` channels and reducing
the overfeeding of water to the `A` channels, there will be some
evaporative cooling; however this arrangement may allow more latent
cooling of the recirculating water than would occur with an
standard evaporative tower under the same conditions.
[0075] For multi-cell units in ambient conditions where operating
in the dry mode provides insufficient cooling, some cells could be
run dry while others wet. The wet section would cool the water
below the setpoint to compensate for the dry section's inability to
reach the required cold-water temperature. The average temperature
of the wet and dry section would meet the required cold-water
temperature and some dry cooling would still be performed. Likewise
a single cell could also be run in a partially-dry mode by sending
some of the hot water in one area of the cell through the standard
spray system while the balance is dry-cooled in other areas of the
tower.
[0076] This invention is not limited to counterflow-cooling towers.
FIG. 3C illustrates how an embodiment of the invention can be
applied to a crossflow cooling tower. In this example the `B`
channel could be the water channel. In the dry mode water would
only pass into `B` channels. The crosshatched areas are indirect
heat exchangers. A person having ordinary skill in the art would be
able to easily apply the variations of the invention previously
illustrated for counterflow cooling towers to crossflow cooling
towers.
[0077] The configurations of the channels do not have to be
identical. Since channel `A` will always contain water, a more
tortuous channel path/configuration may yield improved heat
transfer. Also the bi-directional fill need not be made square.
FIG. 4 illustrates a bi-directional fill with a 2:1 aspect ratio,
in which the length of one set of corrugations is twice the length
of the corrugations in the perpendicular direction. According to
the embodiment shown in FIG. 4, the corrugated sheets with
corrugations aligned in the NW to SE direction are twice as long as
the corrugated sheets with corrugations aligned in the NE to SW
direction (when length of the sheet is measured in the direction
parallel to the corrugations), and the A channels are twice as long
as the B channels. Additionally, the channel entry and exit zones
will increase or decrease correspondingly. As can be seen from FIG.
4, the channel A entry, exit, and intermediate zones are
significantly smaller than channel B entry, exit and intermediate
zones. According to a preferred aspect of this embodiment, Path `A`
would be the water path. In the dry mode very little air would go
through `A`. While this arrangement may have airflow and other
benefits it will have less cross-sectional dry cooling per unit of
height as compared to an arrangement with equal zone widths. For
example, with fill packs having perpendicularly arranged corrugated
sheets of equal length (a 1:1 aspect ratio) the area of indirect
heat transfer is 50%, see FIGS. 2A and 5. Even when the orientation
of corrugations of interleaved sheets are shifted from
perpendicular) (90.degree.), e.g., FIGS. 2A and 5, to a
narrower/taller diamond, in which the angles between interleaved
corrugated sheets is 60.degree./30.degree., the area of indirect
transfer is still 50%, provided that the length of the interleaved
corrugated sheets are equal, e.g., FIG. 6. By comparison, the fill
packs of FIG. 4 cover less than 50% of the cross-sectional area of
the fill area.
[0078] According to a further embodiment of the invention, the open
areas shown in FIGS. 2-4 do not need to be open but can be filled
with omni-directional fill; see FIG. 5. This standard fill would
serve as extra direct heat-exchanger surface area when the tower
was operated in a fully evaporative mode, i.e., in which both spray
heads A and B were providing water to the fill area, and water was
flowing through both channels A and B. In the dry mode there would
be no cooling in the omni-directional fill as either water or air
but not both will pass through that area fill. With the open areas
filled in with omnidirectional fill, the tower will have very
similar evaporative cooling capability as a similar evaporative
tower with the same fill volume and horsepower fan.
[0079] The fill packs according to the invention may also be
elongated, i.e., in which FIG. 6 illustrates an example of a fill
pack elongated in the vertical direction, i.e., in which the
orientation of corrugations of interleaved sheets are shifted from
perpendicular (90.degree.) to 60.degree./30.degree.. Such a
configuration could improve water distribution and lower the
pressure drop from air flowing up the fill. In all other respects,
the embodiment of FIG. 6 operates the same as the embodiment of
FIGS. 2 and 3.
[0080] According to a further embodiment of the invention,
illustrated in FIG. 7A the multiple fill packs in a single fill
pack layer shown in FIGS. 2-6 may be replaced with a single fill
pack made up of a first set of long sheets of fill, corrugated at
an angle, alternating with a second set of long sheets of fill with
corrugations that are perpendicular to, or at some other angle
relative to, the corrugation of the first sheets, where the two
sets of alternating corrugated sheets are separated by intermediate
sheets. A partially exploded view of the fill pack of FIG. 7A is
shown in FIG. 7B.
[0081] According to this embodiment of the invention, channels are
formed between corrugated sheets and adjacent intermediate sheets
such that water entering a channel stays in that channel until it
exits the fill block. FIG. 7A illustrates one direction of the
corrugations, and hence, of the channels. Not shown, is the
direction of the second set of corrugations/channels that travel
across the first set of corrugations (separated by the intermediate
sheets, also not shown in FIG. 7A, The dark lines indicate the
limits of each of zones A.sub.1-A.sub.6 and B.sub.1-B.sub.6. Zones
with an odd subscript (i.e., A.sub.1, A.sub.3, A.sub.5, B.sub.1,
B.sub.3, B.sub.5 go from right to left as the channels move down
the fill pack, and the zones with even subscripts (i.e., A.sub.2,
A.sub.4, A.sub.6, B.sub.2, B.sub.4, B.sub.6) go from left to right
as the channels move down the fill pack. The diamond-shaped areas
are areas of zone overlap. With both sets of spray nozzle on, this
system will function as a typical direct heat exchanger. However,
if air is going through one zone and water through the others, the
diamond areas will act as indirect heat exchangers, cooling the
water without evaporation. More specifically, if one half of the
spray heads are closed, e.g., the B spray heads, and all of the
water is flowing through the A spray heads into the A channels, the
diamond areas of overlap will function as an indirect heat
exchanger.
[0082] Note however, that according to the embodiment of FIG. 7A
there is no exit for water entering zones A.sub.1 or B.sub.6, i.e.,
there are "dead areas" at the ends of the fill pack where the
channels dead end into the side wall. This effect can be
predominately alleviated by modifying the internal intermediate
sheets as shown in FIG. 8A. When the corners of the internal
intermediate sheets are removed/beveled as shown in FIG. 8A, the
dead-areas of FIG. 7A become connected to open paths in the cross
direction from the same zone that allows some water or air flow to
occur. A partially exploded view of the fill pack of FIG. 8A is
shown in FIG. 8B.
[0083] If the zones are of equal width, and if overlapping zones at
the bottom exit of the fill column are to be avoided, the vertical
height of the fill (H) divided by the width of the zones (W) must
equal to the tangent of the angle of the corrugation (.THETA.).
This relationship is illustrated in FIG. 7A. If the fill height and
zone width do not satisfy this relationship, then exit areas will
receive flow from adjacent zones. The bottom layer of fill could be
truncated so long as there was not additional bi-directional fill
below it.
[0084] Alternatively, the height to zone width ratio limitation can
be avoided as shown in FIG. 9A, by stacking fill packs of the type
shown in FIG. 7A on top of one-another, but reversing the angles of
corrugation for each channel, e.g., by rotating the second layer
fill pack 180.degree. horizontally, relative to the fill pack of
the first layer fill pack, and optionally adding additional layers
of fill pack, reversing the orientation of each relative to the one
above, so that the channels zig-zag down the fill column. Partially
exploded views of the three layers of the fill pack of FIG. 9A are
shown in FIGS. 9B, 9C and 9D. By using any number of zigs and zags,
or "doglegs," the fill height can be made in multiples of the tan
(.THETA.).times.W.
[0085] By sending all of the water through one set of paths in the
fill and none of the water through the other, the resistance to
airflow will be greater in the paths with the water. Under typical
water-flow rates of 6 gpm per square foot, this greater air
resistance will result in a split of airflow such that
approximately 55% of the air will go through the dry path and 45%
of the air will go through the wet path even when the paths have
the same cross-sectional area. While this will lead to significant
water use reduction for a tower, with many ambient conditions even
more water could be saved if there were more than 55% of the air
passing through the dry section.
[0086] Another embodiment of this invention has one of the paths
designated as a "wet-path" and the other designated as a
"dry-path". The wet-path would be narrowed down in cross-sectional
area while the dry-path would be opened up. This will increase the
resistance to air-flow in the wet-path and reduce it in the
dry-path. By this change, a higher percentage of air than 55% will
go through the dry-path. The percentage of air in the dry path can
be adjusted by adjusting the cross-sectional areas of the two
paths. This higher percentage will allow more water to be saved in
many ambient conditions than the 45%/55% split achieved with equal
cross-sectional area paths.
[0087] FIG. 10 illustrates another embodiment of the invention.
According to this embodiment, the indirect heat exchanger covers
more than 50% of the fill-pack area. As with prior embodiments, the
embodiment represented by FIG. 10 may be constructed with
alternating sheets (stacked into the page, from the view of FIG.
10), but in this embodiment, all the channels run vertically at the
center of the fill column. Since the columns are vertical, the
intermediate sheets of FIGS. 2-9 are not necessary (although they
may still be used). Instead, the intermediate sheets of FIGS. 2-9
may be formed with ribs to separate each sheet from adjacent sheets
thereby creating the channels. According to this embodiment, each
internal sheet has one set of channels on a first side, and a
second set of channels on an opposite side. One half of the
channels are vertical from top to bottom. The other half of the
channels shift to the right at the top of the column, in order to
form overlapping water/air zones, and then optionally shift back to
the left, so that the exit zones do not overlap. Zones denoted with
odd subscripts, i.e., A.sub.1, A.sub.3, A.sub.5, B.sub.1, B.sub.3,
and B.sub.5, denoted by solid lines, shift to the right at the top,
then drop vertically, then optionally shift back to the left at the
bottom of the column. Zones denoted with even subscripts, i.e.,
A.sub.2, A.sub.4, A.sub.6, B.sub.2, B.sub.4 and B.sub.6, denoted by
dashed lines, and which reside in front of and behind the odd
Zones, looking through the page, drop straight down the column from
top to bottom.
[0088] Looking at a typical zone B.sub.3/B.sub.4, on the side
represented by solid lines the B.sub.3 doglegs right, flows
straight down to the bottom of the pack then doglegs left to exit.
On the side represented by dashed lines B.sub.4 flow goes directly
down and recombines with the B.sub.3 flow at the exit. (Note this
recombination is only to separate the air from the water exits to
minimize aspiration of water into a dry channel and may not be
necessary.) In the shaded areas behind the B.sub.4 zone is A.sub.5
and behind the B.sub.3 zone is A.sub.4. With water flowing through
A and air only in B there will be an indirect heat exchanger. On
the left edge of the fill pack, zone A.sub.1 and B.sub.2 are double
width to eliminate an otherwise dead area opposite zone A.sub.2
since there is no B.sub.0 to flow behind it.
[0089] The standard-fill as illustrated results in individual
channels running from top to bottom of the fill.
[0090] FIGS. 11-13 illustrate one way according to which the
embodiment of FIG. 10 may be fabricated. FIG. 11 shows the parts
that may be assembled to make the two sets of alternating sheets.
FIG. 12 shows the assembly of parts to make assembly A, a first set
of sheets, and FIG. 13 shows the assembly of parts to make assembly
B, a second set of sheets. The solid lines represent ridged/ribbed
bonding surfaces where the sheets are bonded to one another to
create the channels; the dashed lines indicate an end of the part,
which is bonded to a part of the same sheet to create an assembled
sheet. Each rib/ridge on the front side of parts A, B, and C, has a
corresponding rib/ridge on the reverse side. A cross-sectional view
of Part B is shown in FIG. 13A. These three different parts are
assembled as shown in FIGS. 12 and 13.
[0091] In assembly A, Part `A` is attached atop Part `B` as shown.
Going from top to bottom Part `A` will, in general, index over one
column to the right. At the bottom of the assembly Part `A` is
flipped 180.degree. horizontally and will index over one column to
the left effectively returning the output of the column to below
its original input. The leftmost column becomes a double column due
to the edge effect of the fill-pack. The center of the sheet
identifies if a column carries water or air. As illustrated in, the
columns in assembly A alternate between water and air with the
left-most column being a water column.
[0092] In assembly B, Part `C` is attached atop Part `B` as shown
in FIG. 13. In general part `C` will direct each column straight
down. At the bottom of the assembly Part `C` is flipped 180.degree.
vertically. The center of the sheet identifies if a column is a
water or air column. As illustrated, the columns in assembly B
alternate between water and air with the left-most column being an
air column.
[0093] The fill pack is constructed by alternating assembly A with
assembly B. In the cross-sectional view, every water column on
assembly A is sandwiched between two air columns on the assembly B;
one in front and one behind. Likewise every water column of
assembly B is sandwiched between two air columns on assembly A. An
indirect heat exchanger is then constructed where the warm water in
one column is cooled by the cool air passing in columns in front
and in back of it.
[0094] The advantage of embodiment illustrated in FIGS. 11 through
13 is that instead of a full intermediate sheet, only the top and
bottom of the intermediate sheet is needed. For a 4-foot high pack
with 8'' wide columns, the combined height of Part `A` and Part `C`
would be 16'', savings two thirds of the material of the
intermediate sheet. Since every other sheet is an intermediate
sheet, this embodiment will save 33% of the materials for a 4-foot
pack and even more for taller packs.
[0095] FIG. 14A illustrates a cross section of part B, of FIG.
11.
[0096] FIG. 14B illustrates a cross section taken in the middle of
the fill-pack illustrated in FIG. 10. The ribs/ridges of the sheets
have been exaggerated to show sealing points. An individual sheet
is shown in heavy line in the middle of the pack. Each sheet is a
mirror image of the adjacent sheets on each side. Each set of
adjacent sheets defines a set of channels. All heat transfer occurs
across these sheets. Water paths are denoted by cross-hatches. The
cross-sectional areas of the water and air paths are equal and
should result in an airflow split of 55%/45% with typical water
loading. A checkerboard pattern of air-channels and water-channels
are shown.
[0097] FIG. 15 shows an embodiment in which the profile of the
sheets are modified such that the designated water channels (with
cross-hatches) are smaller than the designated air path. This will
result in an airflow split such that the amount of air passing
through the air path is >55%. The airflow split can be modified
by changing the ratio of the water-path area to air-path area.
Again an individual sheet is shown in heavy line in the middle of
the pack. Each set of adjacent sheets, with each sheet a mirror
image of adjacent sheets, defines a set of channels.
[0098] FIG. 16 shows another embodiment of the invention. This
embodiment completely eliminates the multiple-element sheet
assembly of FIGS. 11-13. According to this embodiment, the complete
bi-zonal fill may constructed using a single repeating sheet. On
Figure, 16 single lines indicate a bonding ridge coming out of the
plane of the sheet, and double lines indicate a bonding ridge going
into the plane of the sheet. Triple lines indicate a bonding ridge
coming out of the sheet next to a bonding ridge going into the
sheet. The sheet is symmetrical about a horizontal axis at the
midsection. Taking a first sheet having the orientation shown in
FIG. 16, and by attaching a second sheet flipped 180.degree. about
this axis atop the first sheet, the bonding surfaces indicated by
single lines will mate and form the channels indicated by the heavy
lines in FIG. 17.
[0099] By attaching a third sheet flipped 180.degree. about this
axis behind the first sheet, the bonding surfaces indicated by
double lines will mate and form the channels indicated by the heavy
lines in FIG. 18. Thus with multiple copies of this single sheet, a
fill pack can be assembled without resorting to the three-part
construction shown in FIGS. 11-13 or with intermediate corrugated
fill sheets. As with previous designs, the cross-sectional area of
the water-path and air path can be adjusted by changing the height
of the bonding surfaces. The advantage of this design is that it
completely eliminates corrugated sheet, makes assembly simpler, and
requires only a single mold for thermoforming.
[0100] It would be an advantage to be able to increase the height
of the fill pack without having to make separate thermoforming
molds or gluing together sheets of fill to make a taller sheet.
Also, assembling very tall fill packs in cooling towers becomes
difficult. The difficulty in simply stacking bi-zonal fill packs on
top of each other is that if the channels do not line up exactly,
water can get into an air-channel which reduces the dry-cooling
ability of the pack. FIGS. 19 through 22 illustrate an embodiment
of the invention that allows for a stackable fill pack. FIG. 19
shows the straight channels, and FIG. 20 shows the indexed
channels. The dark lines indicate the seal points. The top and
bottom of the fill are crenellated to allow stacked packs to nest
together. The crenellation at the top is evenly spaced--with the
water channels always notched down and the air channels protruding
upwards. The crenellation at the bottom is not evenly spaced. The
water channel is narrower and the air channel is wider. The water
channel tapers to a funnel shape. The bottom air-channel profile is
slightly deeper and wider than the water-channel profile. When fill
packs are stacked, the bottom of one pack's water channels will
then touch the top of the next pack's water channels, while a gap
will remain between the air channels of the two packs. This
arrangement will prevent water from a water channel from leaking
into an air channel.
[0101] Typical thermoforming machines used to make fill have a
maximum forming area of approximately 4'.times.4'. Fill can be
formed larger than this in one direction if there is a repeating
pattern. FIGS. 21 and 22 illustrated an embodiment that allows
wider fill-packs to be assembled. The heavy lines indicate seal
points. The shaded areas show potential cut lines. Both FIGS. 21
and 22 indicate a cut lines after each of 2 repeating motifs. If,
for example, each motif was 3' long on a 4' wide sheet, then fill
packs that were 6' or 9' wide by 4' high could be assembled. By
stacking two layers of crenellated-fill-packs, a cooling tower
could be equipped with 8' high of fill.
[0102] FIG. 23 illustrates a modification of FIG. 10 such that the
columns are indexed only 1/2 column width to the left. FIG. 24
illustrates the second sheet in this design where all the columns
are indexed 1/2 a column width to the right. FIG. 23 shows an
embodiment of the invention where, like FIG. 10, the indirect heat
exchanger (shaded) covers more than 50% of the fill-pack area. At
the top and bottom of each column the unshaded triangles are areas
where there is no indirect contact of an air column with a water
column and therefore no indirect heat transfer. Good practice has
the hypotenuse of these triangles to be at least 45.degree. from
the horizontal. If a column was 1-foot wide, then the area of each
triangle would be 0.5 ft.sup.2 for a total area of 1 ft.sup.2 of no
indirect heat exchanger per column. This area is the same
regardless of the height of a column. For a 4' high column, 25% of
the area of the column is not part of the indirect heat exchanger;
for a two-foot high column this would increase to 50%.
[0103] Both outside columns are now double-wide columns, as
compared to the embodiment of FIG. 10 in which only the left-side
was a double column. But like the embodiment of FIG. 10, the double
columns are indirect heat exchangers since a water double-channel
will be sandwiched between two air double-channels. On FIG. 24 the
areas of no indirect contact between water and air columns are
shaded. If the columns are 1-foot wide and the angles are again at
45.degree., the shaded triangles are (1/2+(1/2).sup.2)=0.707' on a
side. The area of each shaded triangle is
(0.707).sup.2.times.1/2=1/4 ft.sup.2. In FIG. 24 there are 8 shaded
triangles for a total of 2 ft.sup.2. If the Sheet is 6' wide by 4'
high then there are 24 ft.sup.2 of sheet area. The area that is not
part of the indirect heat exchanger is 2/24=8.3%. Even if the sheet
was only 2' high the percentage of area that is not part of the
indirect heat exchanger is only 2/12=16.7%.
[0104] FIGS. 25 and 26 illustrate how this embodiment can be
thermoformed on standard equipment to make tall fill packs and
eliminating the requirement for stacking. The designs in FIGS. 25
and 26 consist of a two-foot long repeating motif on a four-foot
wide sheet. The repeating motif is shown with dashed-lines. This
repeating motif allows a four-foot wide fill pack to be constructed
in heights of 2', 4', 6', 8', etc. In FIGS. 25 and 26 cut lines are
shown that would produce a 6' high fill pack. In FIG. 26 areas
where there will be no indirect heat exchanger are illustrated as 4
diamond-shaped areas and 4 triangular-shaped areas. Each
triangular-shaped area is 1/4 ft.sup.2 while each diamond shaped
area is 1/2 ft.sup.2. The total area with no indirect heat
exchanger is then 3 ft.sup.2. Since each sheet is 24 ft.sup.2,
there will be 21/24=87.5% of the fill area as an indirect heat
exchanger.
[0105] This invention will require a different water distribution
method than a standard cooling tower. Each water column will
require a separate spray-branch. By aligning the fill packs a
single spray branch can extend the entire length or width of a
cell. With a 1' wide column, there would need to be a spray branch
every 1-foot. The number of spray branches can be reduced by having
2 separate spray systems. One would be a standard spray system and
would be used when the tower was operating in a fully wet mode. A
second spray system would be located over every other column and
would be used when the system was operating in a "dry" mode. In a
typical 36'.times.36' cell this will result in 18 additional spray
branches to be used when operating in the dry mode. The number of
spray branches can be reduced by aligning the fill packs as shown
in FIG. 27. The fill packs used in FIG. 27 are 4'long by 1' wide by
6' high, though the height is not important. Each fill pack has 17
sheets spaced approximately 0.75'' apart. The fill packs shown have
four channels as shown in FIGS. 25 and 26 though any of the
embodiments of the invention could as easily be used. By
alternating the orientation of the blocks when assembling the fill
in some places two water-columns will be next to each other
allowing a single spray branch to feed two columns. On the 36' wide
cell shown in FIG. 27 only 14 secondary spray branches are
required.
[0106] This minimal amount of additional spray-branches is a
dramatic improvement over the prior art. U.S. Pat. No. 3,997,635
describes using separate spray nozzles between parallel sheets.
Similar designs are used in U.S. Pat. Nos. 4,337,216 and 5,775,409.
In this prior art, to form an indirect heat exchanger, spray
branches must be placed along every other sheet. For the cell in
FIG. 27, the prior art would require 8 spray branches each 36' long
for every foot of cell width. Since the cell is 36' wide this will
result in 8.times.36=288 spray branches. It would be impractical to
equip a cell in this manner. As noted in the previous paragraph,
with this invention the cell could be treated with as few as 14
additional spray branches.
[0107] FIGS. 28A and 28B shows an improvement to the embodiment of
FIGS. 23 and 24. The 1/2 column index design illustrated in FIGS.
23 and 24 requires one more input-region than vertical columns.
Specifically, FIGS. 23 and 24 show 6 input-zones and 5 vertical
columns. FIGS. 28A and 28B illustrate a 5-input-zone embodiment of
the invention. FIG. 28A illustrates the "A-sheet" for a
modification of the half-column-index illustrated in FIG. 23, and
FIG. 28B illustrates the "B-sheet" for a modification of the
half-column-index illustrated in FIG. 24. An operational concern of
the bi-zonal design is the ability to move water from its
input-zone laterally to the part of the fill where indirect cooling
occurs. For the design in FIGS. 23 and 24, some of the water
entering into the leftmost "W" region of FIG. 23 must move
laterally to the left a full column width. Water entering the other
"W" regions must move laterally only 1/2 a column width. The
embodiment of FIGS. 28A and 28B eliminates the requirement for a
full column lateral movement by using an odd number of input-zones
(FIGS. 28A and 28B illustrate 5 input-zones) with the outer
input-zones being water zones. The embodiment of FIGS. 28A and 28B
has 5 equal-width input-zones and 4 unequally-sized vertical
columns. The inner two columns are the same width as the
input-zones and the outer two columns are each 11/2 times the width
of the input-zones. Water entering any of the three "W" regions are
only indexed a maximum of 1/2 a column width laterally.
[0108] FIG. 29 (bottom) shows an additional modification to the
embodiment of FIGS. 28A and 28B. The top of FIG. 29 is simply a
repeat of sheet "B" from FIG. 28B, for comparison purposes. As
shown in 28B and in the top of FIG. 29, this embodiment has 5
equal-width input-zones with water on the outside and center zones
and 4 columns with the two inner columns being the same width as
the input-zones and the two outer columns being 11/2 times the
width of the input-zones.
[0109] By contrast, in the embodiment shown at the bottom of FIG.
29, the vertical columns are all the same width but the outer
input-zones are 1/2 the width of the three interior input-zones. As
in the arrangement illustrated in FIG. 28B, water entering any of
the water-input zones must move laterally only 1/2 a column width.
According to an alternative embodiment, the outer water input zones
could be made larger than 1/2 a column width by making the interior
input zones narrower. In "dry" mode this would result in moving
water less than 1/2 column width although it would require moving
water more than 1/2 column width in "wet" mode. If a tower has
excess capacity in the wet mode, such a change would improve dry
performance without undue sacrifice of wet performance."
[0110] With both of these designs the fill assemblies are
preferably stacked side-by-side in a cooling tower such that the
outer water columns of two adjacent fill blocks will be fed by a
single spray nozzle.
[0111] FIG. 30 illustrates another embodiment of the invention
which employs Coand{hacek over (a)}-effect spoons. Water entering a
wet input-zone must be moved 1/2 column width laterally. For the
center wet input-zones, water falling on the front of the sheet
must move to the left while water falling on the back of the sheet
must move to the right. In the hybrid mode water will only fall on
both sides of the center water-input-zone, but in the fully
evaporative mode water will fall on both sides of all the
air-input-zones, as well. Since the sheets are typically
thermoformed, any structure on the front of the sheet will result
in the inverse structure on the back. Thus, ridges to direct water
to the left on the front of the sheet will result in valleys that
direct water in the wrong direction on the back. This problem is
resolved by the Coand{hacek over (a)}-effect spoons illustrated for
Sheet A in FIG. 30. The spoons are preferably curved structures,
preferably about 1/2'' tall and tapered wider bases and narrower
tops. According to preferred embodiment, the bases are about 3/8''
wide and the tops are about 1/8'' wide, with a draft angle of
approximately 109 degrees (see, e.g., FIG. 31). This geometry aids
in water distribution and formability of the thermoformed sheet.
The shaded spoons in FIG. 30 come out of the page (toward the
reader) while the unshaded spoons go into the page (away from the
reader) forming raised spoons on the backside of the sheet. Sheet B
is a mirror-image of Sheet A in this region which results in the
spoon shapes lining up to completely cross the channel.
[0112] Water falling on the top of the spoons that come out of the
page will be directed to the left. Water touching the back-side of
the spoons will also be directed to the left by the Coand{hacek
over (a)}effect. Water entering the spoons that go into the page
will not be moved laterally in either direction. Overall, water
falling on the front of the page will move to the left while water
falling on the back of the sheet will move to the right.
[0113] FIGS. 31 and 32 show another embodiment of the invention
using Coand{hacek over (a)}-effect spoons. According to this
embodiment, the spoons on one side of the input zone are formed in
one direction perpendicular to the plane of the sheet, and the
spoons on the other side of the input zone are formed in the
opposite direction perpendicular to the plane of the sheet. The
spoons are curved toward the intended direction of water flow at
90-160 degrees from horizontal, preferably 120 degrees, measured to
the tangent of the curve center.
[0114] FIG. 33 illustrates another embodiment of the invention,
this one including dampers for the water input-zones. The quantity
of air that passes through the wet section will affect the amount
of dry cooling that can be achieved. In the wintertime when the
ambient temperature is low, significant amount of dry cooling can
be achieved by severely limiting the amount of air passing through
the wet columns. In the summertime with higher ambient
temperatures, if only a little air is passing through the wet
columns the tower may not be able to meet cooling requirements in
the hybrid mode. When this happens some cells must be operated in
the full evaporative mode or the entire tower much switch to the
full evaporative mode with no water savings.
[0115] With dampers on the water input, the split of air between
the wet and dry sections can be easily modified. FIG. 33
illustrates dampers on the air exit from the wet regions of the
fill but they could easily be located on the input to the
wet-regions of the fill or on both the input and exit. The dampers
could be built to be manually adjusted or they could be built to be
automatically adjusted. If they are automatically adjusted they
could be combined with a speed-controlled fan to provide the
maximum dry cooling under all ambient conditions. The maximum water
savings will occur with settings such that the least amount of air
passes through the wet section while the system is still able to
meet cooling requirements. Adjustable dampers allow this to occur
over a wide variety of ambient conditions.
[0116] The descriptions of this invention have not specified
material of construction. Typically fill is made of PVC which has
poor thermal conductivity. In the indirect heat transfer mode this
poor conductivity will hurt performance. If the PVC sheet and
corrugations are kept thin then problem is lessened. Different
plastics or metal sheets with higher thermal conductivity would
improve the heat transfer. In particular stainless steel alloys
such as 304 or 430 would improve the indirect cooling
properties.
* * * * *