U.S. patent application number 11/527796 was filed with the patent office on 2007-01-25 for indirect-direct evaporative cooling system operable from sustainable energy source.
This patent application is currently assigned to Speakman Company. Invention is credited to Samuel Hyland, Robert F. Lobozo, Covington Stanwick.
Application Number | 20070017241 11/527796 |
Document ID | / |
Family ID | 35512496 |
Filed Date | 2007-01-25 |
United States Patent
Application |
20070017241 |
Kind Code |
A1 |
Hyland; Samuel ; et
al. |
January 25, 2007 |
Indirect-direct evaporative cooling system operable from
sustainable energy source
Abstract
Improved means for powering and increasing evaporative cooling
in an indirect-direct evaporative cooling (IDEC) apparatus are
disclosed. Sustainable energy from solar energy mixed with grid
power, when needed, power the IDEC device. These DC and AC power
sources are seamlessly merged in a unique diode interconnect unit.
Improved means for evaporative cooling include a rayon-based
flocking on the wet side of molded plastic indirect evaporative
cooling plates. Separate wet and dry passages through those plates
are facilitated by a unique means for clamping the upper ends of
the plates. These clamping means also add to the structural
integrity of an array of plates so that the array can be inserted
in and removed from a housing containing other operational
components of the IDEC such as fan, direct cooling plates and water
distribution means. Applicants IDEC utilizes improved porous piping
that allows uniform and continuous distribution of water to all wet
passages within both the indirect and direct stages of the IDEC.
Operational controls for the system limit the potential water
damage caused by overflow of water from the IDEC housing.
Inventors: |
Hyland; Samuel; (Wilmington,
DE) ; Lobozo; Robert F.; (New Castle, DE) ;
Stanwick; Covington; (Aquasco, MD) |
Correspondence
Address: |
Connolly Bove Lodge & Hutz LLP
1007 North Orange Street
P.O. Box 2207
Wilmington
DE
19899
US
|
Assignee: |
Speakman Company
New Castle
DE
|
Family ID: |
35512496 |
Appl. No.: |
11/527796 |
Filed: |
September 27, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10880668 |
Jun 30, 2004 |
7143597 |
|
|
11527796 |
Sep 27, 2006 |
|
|
|
Current U.S.
Class: |
62/236 ;
62/235.1; 62/314 |
Current CPC
Class: |
F24F 1/0007 20130101;
F28D 5/02 20130101; F24F 2006/046 20130101; F24F 5/0035 20130101;
F24F 5/0046 20130101; Y02B 30/54 20130101; Y02B 30/545
20130101 |
Class at
Publication: |
062/236 ;
062/235.1; 062/314 |
International
Class: |
F25B 27/00 20060101
F25B027/00; F28D 5/00 20060101 F28D005/00 |
Claims
1-5. (canceled)
6. A hydrophilic coating for a heat exchange plate useable in the
indirect evaporative cooling stage of indirect-direct evaporative
cooling (IDEC) system comprising a flocked rayon-based material
deposited on the plate.
7. The hydrophilic coating of claim 6 comprising a random cut rayon
material deposited on the plate.
8. The hydrophilic coating of claim 6 wherein the rayon material is
random cut and has an approximate average length of about 0.020
inches.
9. The hydrophilic coating of claim 7 wherein the rayon material
has an approximate pile height of about 0.005 inches.
10. The hydrophilic coating of claim 6 wherein the coating is
attached to the plate with an adhesive.
11. The hydrophilic coating of claim 10 wherein the adhesive is a
vinyl acetate monomer.
12. A fluid delivery device for releasing fluid useable for
evaporative cooling of a gas is an evaporative cooling apparatus
comprising a porous container for such fluid located above the
evaporative cooling apparatus.
13. The fluid delivery device of claim 12 wherein the porous
container is located above: a) the indirect cooling stage of an
indirect-direct evaporative cooling (IDEC) system; b) the direct
cooling stage of an IDEC system; or c) both the indirect and direct
stage of the IDEC system.
14. The fluid delivery device of claim 12 wherein the porous
container is porous plastic piping.
15. The fluid delivery device of claim 14 wherein the porous
container is porous high density polyethylene piping.
16. The fluid delivery device of claim 12 wherein the porous
container is in physical contact with the evaporative cooling
apparatus to promote uniform discharge of the fluid into the
cooling apparatus.
17. An indirect-direct evaporative cooling (IDEC) apparatus
comprising a) a unitary molded housing; b) an outside air entrance
into the housing; c) a fan for moving outside air through the
housing; d) a direct evaporative cooling stage within the housing
for evaporative cooling of outside air; e) an indirect evaporative
cooling stage within the housing for evaporative cooling of outside
air comprising an array of multiple parallel plates, one side of
the plate being wetted during operation and the other side being
essentially dry, and f) U-shaped clamps arranged to selectively
close portions of the parallel plates to create wet and dry
passages through the plates.
18. The IDEC apparatus of claim 17 wherein the U-shaped clamps are
formed from a hardened, corrosion resistant material.
19. The IDEC apparatus of claim 18 wherein the U-shaped clamps are
stainless steel.
20. The IDEC apparatus of claim 18 wherein the U-shaped clamps are
aluminum.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a highly efficient system and
apparatus for supplying conditioned air to an interior space. The
system utilizes two stage evaporative cooling to deliver
conditioned air to living and work spaces, namely indirect and
direct cooling stages. Such cooling is often identified by the
acronym IDEC which stands for indirect/direct evaporative cooling.
This invention seamlessly draws operating power from multiple AC
and DC sources including a utility power grid and/or sustainable
energy sources such as solar panels. A unique combination of
indirect stage heat exchanger plate coatings and water distribution
manifolds enhances the operation of the IDEC apparatus used in the
system.
[0003] Other IDEC systems are described below. For example, U.S.
Pat. No. 5,664,433 issued Sep. 9, 1997 to Davis Energy Group, Inc.
("Davis I") describes an indirect-direct evaporative cooling
apparatus with a single initial stream exiting a blower at the
bottom of the apparatus that splits into primary and secondary
streams that flow in a crossflow pattern through the indirect
evaporative cooling stage. The primary air stream is directed
horizontally through the indirect cooling stage and then through
the direct cooling stage. The secondary air stream is directed
vertically through the indirect cooling stage to evaporatively cool
the air passing therethrough.
[0004] A pending application (Ser. No. 10737,823) assigned to the
owners of U.S. Pat. No. 5,664,433, Davis Energy Group, Inc.,
("Davis II") notes several limitations of the Davis I patent
allegedly cured by the IDEC apparatus disclosed in that
application. More specifically, Davis II relocates the air handling
fan to the top of the apparatus which reduces air flow and water
handling problems apparently experienced with apparatus disclosed
in Davis I. Davis II also utilizes a crossflow air pattern for the
indirect heat exchanger stage that simplifies the construction of
the apparatus. According to Davis II, the crossflow of air also
increases the air path distance which, in turn, increases the
efficiency of the unit. Davis II also discloses a simplified
internal plate structure for the indirect cooling stage which
enables the plates to interlock into an assembly, yet maintain
spacing of air (dry) and water (wet) channels on opposite sides of
the plates.
[0005] Another patent assigned to the Davis Energy Group, Inc. is
U.S. Pat. No. 6,574,975 issued Jun. 10, 2003 ("Davis III"). It
discloses a system for distribution of water in an evaporative
cooling apparatus. More particularly, water which drips through
evaporative cooling plates is collected in a sump and recycled to a
water distribution manifold above the plates. The manifold
disclosed in Davis III is little more than a horizontal perforated
pipe which sprays on the underside of a semi-circular distribution
surface that disperses the sprayed water over the top of the
evaporative cooling media. (See reference numbers 36a, 60 of FIG.
2).
[0006] Other approaches to water distribution above evaporative
cooling media are discussed in U.S. Pat. No. 5,192,464 issued Mar.
9, 1993. This patent discloses water distribution conduits 66 with
discharge slots 68 cut in the top thereof (FIG. 5 and column 4,
lines 46-6). The water exiting those slots dribbles down in a
rather uncontrolled fashion over the evaporative cooling media. In
U.S. Pat. No. 5,349,829 water distribution manifolds 152, 162
contain a plurability of downwardly directed spray nozzles 154, 164
which discharge onto the top surface of the evaporative cooling
media (FIG. 1; column 4, lines 56-67). Yet another water
distribution system for an evaporative cooler is illustrated in
U.S. Pat. No. 4,427,607. In this patent outlets are located in the
water distribution manifold so that they align with the wet side of
evaporative cooling media. Conversely the dry side of the media is
isolated from such outlets. (See FIG. 3 and column 3, lines
11-67).
[0007] Another supplier of IDEC units is AdobeAir, Inc. of Phoenix,
Ariz. which sells such units under the MASTERCOOL.RTM. trademark.
AdobeAir's web page (www.adobe.com) describes IDEC units with
vertical fins which have water running therethrough to cool outside
air passing over the outside of the fins
[0008] One approach to powering cooling equipment, more
particularly a regular compressor driven air conditioner, is
illustrated in U.S. Pat. No. 4,697,136 issued on Sep. 29, 1987. In
this patent solar panels are connected in series as a source of
direct current (DC). This DC solar power is supplemented or
replaced with a commercial alternating current (AC) power source to
run the air conditioner. These dissimilar (AC and DC) power sources
are wired through an inverter system that provides flexible
utilization of DC solar power alone, DC in combination with AC
power or AC power alone. Selection of power sources is determined
by a controller which switches power sources and inverters into and
out of the power supply to the cooling equipment as illustrated in
the only drawing in the patent (See also column 2, lines 29-64).
U.S. Pat. No. 6,583,522 issued Jun. 24, 2003 describes a switching
system that permits control of solar power by selective
configuration of solar panels into series, parallel or
series--parallel arrangements. This switching system permits
control of voltage and amperage out of the solar panel. Another use
of solar power in a cooling system in disclosed in U.S. Pat. No.
4,281,515 issued Aug. 4, 1981 to Energy Wise, Inc. of Lodi, Calif.
This patent discloses use of solar heat (not power) linked to the
absorption refrigeration cycle of a cooling system.
SUMMARY OF THE INVENTION
[0009] Indirect/direct evaporative coolers are well suited for
operation with sustainable energy, particularly solar power. More
particularly, IDECs operate best in low humidity climates such as
those found in the southwest quadrant of the United States. These
areas of the country, coincidentally, have long periods of
continuous sunshine that can be used to power solar panels. Thus,
the marriage of solar power and IDECs offers a unique opportunity
for cooling homes, offices, work places and factories in that
portion of the United States at minimum cost because most operating
power can be supplied by the sun. One form of solar panel suitable
for use in this invention is that offered by First Solar, LLC
Perryburg, Ohio (www.firstsolar.com). Even without solar power, the
IDEC disclosed herein provides highly efficient cooling with about
an eighty percent (80%) reduction in power consumption compared to
vapor compression air conditioning systems. In the preferred
embodiment of applicants' IDEC, both AC and DC are made available
for its operation. The use of twin power sources is facilitated by
a unique arrangement of components. Unlike the prior art approach
discussed above, applicants achieve a seamless blend of solar (DC)
and grid (AC) power sources without use of inverters. This
arrangement allows applicants' IDEC to be run during peak afternoon
sun loads at little or no cost because solar power supplies
substantially all of the energy needed to operate the IDEC. As the
sun sets, the temperature of outside air also lowers thereby
reducing the amount of cooling needed. Thus, applicant's IDEC using
solar power operates in synchronization with nature's daily rhythm
to supply cooled air throughout the day at little or no cost.
[0010] These operational savings are also made possible by vastly
improved water distribution and wetting within applicants' IDEC. A
central operating principle of IDECs is the evaporation of water
from one (wet) side of heat exchange plates within the indirect
stage of the IDEC. The greater the area of evaporation the greater
the cooling in this stage of the IDEC. To increase the area of
evaporation it is important that the wet side of the heat exchange
plates in an IDEC be completely and uniformly wetted. That goal is
accomplished in this invention in several ways. First, the wet side
of the heat exchange plates is coated with a unique flocked
rayon-based material. This material absorbs and holds small amounts
of water in contact with the wet side of the heat exchange plate.
Once contacted by a continuous flow of water, this material evenly
distributes and maintains a saturation state of its surface area as
a result of its wicking properties. As air is passed over the
flocked material, the water in that material evaporates thereby
evaporatively cooling the heat exchange plate. Outside air passing
on the other (dry) side of the heat exchange plate is thereby
cooled before it is ultimately discharged into the occupied space.
This flocked, rayon-based material, which is bonded to plastic such
as polyvinyl chloride (PVC), is available from Flock Tex
Incorporated, Woonsocket, R.I. and is sold under the Flock-Tex
trademark (www.flocktex.com).
[0011] Another feature of this invention that contributes to the
uniform wetting of the flocked heat exchange plates is an improved
water distribution manifold. More specifically, applicants utilize
porous plastic piping in their manifold to evenly supply and
distribute water to the heat exchange plates of the indirect
cooling stage of the IDEC. This porous plastic material is also
used to distribute water to the foraminous material used in the
direct cooling section of the IDEC. One type of porous plastic
piping found particularly useful by applicants is porous high
density polyethylene (HDPE) piping manufactured by Porex
Corporation located in Fairburn, Ga. (www.porex.com).
[0012] The indirect cooling section of applicants' IDEC unit
disclosed in Davis II includes parallel heat exchange plates to
separate the wet and dry passages through the heat exchanger. The
alternating wet and dry passages are formed by folding individual
plastic sheeting, for example sheets made of PVC or polyethylene,
into a U-shape. To create separate wet and dry passages through the
heat exchanger, it is necessary to effectively seal a portion of
the upper edges of alternating wet and dry passages at the top of
the U-shaped plate pairs. More specifically, air that is to be
conditioned enters open passages into the dry side of the heat
exchanger plates toward the back of the heat exchanger immediately
below a blower fan used to force air through the system. Conversely
the alternating wet passages (surfaces) in the indirect cooling
stage are closed in the area immediately beneath the blower so that
the air exiting the blower does not enter the wet passages at this
point.
[0013] The forward (toward the conditioned air exit) portion of the
upper surface of the wet passages in the indirect cooling section
of the IDEC must, however, be open to receive water needed to
evaporatively cool the plates of the heat exchanger. Thus, the
upper edges of the wet passages immediately below the fan blower
exit must be closed, yet provide for an opening to receive water
elsewhere on that upper edge. This arrangement of openings is
achieved by applicants' use of a unique clamping arrangement of the
plates across the top of the indirect cooling section of the IDEC.
More specifically, across the area under the blower, the folded
plates forming the wet passages are clamped together with a rigid,
corrosion-resistant U-shaped retaining clamp, preferably stainless
steel or aluminum. In the area under the water manifold the plates
leading to the dry passages are clamped together to restrict
entrance of water to those passages, while conversely channeling
water from the manifold into the wet passages.
[0014] The water path from manifold into the wet passages is
further assisted if the preferred porous plastic piping used in the
manifold is in physical contact with the U-shaped clamps
immediately under the manifold. Such contact improves the water
flow from the manifold into the wet side of the plates. To further
improve water flow into and through the wet side passages, the
upper end of the wet passages preferably contains a water channel
or groove from the front to back of the wet (flocked) side of the
wet passage plate. This channel collects water from the manifold
and the water therein flows to the back of the plate, thereby
insuring complete wetting of the wet passages from front to
back.
[0015] The direct cooling section of applicants' IDEC includes a
foraminous member which is wetted by the same type of porous piping
used to wet the indirect cooling section. The foraminous member,
typically a cellulose material, is preferably formed as corrugated
sheets with a multiplicity of polygonally shaped openings such as
that described is U.S. Pat. No. 4,562,015 issued Dec. 31, 1985 to
the Munters Corporation of Ft. Myers, Fla. This material is sold by
the Munters Corporation under the trademark Celdek
(www.munters.com). The direct cooling section of applicants' IDEC
cleanses, humidifies and further cools the air previously
conditioned in the indirect cooling section.
[0016] The air flow pattern through applicants' IDEC is generally
as described in Davis II. All air processed through this system is
fresh, outside air which fills the area to be conditioned and exits
through roof or attic vents. Internal recirculated air is not used.
Outside, low humidity air, at a typical temperature of
90.degree.-110.degree. F. is drawn into the system with a fan
powered by AC or DC as described above. The outside air exits the
fan in an area above a portion of the plates of the indirect stage
of the system. In this area of the plates, the entrance to the wet
side of the plates is blocked by the U-shaped clamps as previously
described. This channels the entering outside air into the dry
passages within the plates. Within the dry passages, the hot
outside air is in contact with the plate surfaces that are being
cooled by evaporation of water on the wet side of that plate in the
indirect stage of the IDEC. Passage of low humidity hot air through
the indirect stage typically lowers the temperature of the air by
about 10 to 20.degree. F. The air temperature is further lowered by
evaporative cooling in the direct stage so that it exits the IDEC
into the conditioned space at a temperature of about 68.degree.
F.
[0017] Because the foraminous member in the direct stage of the
IDEC is relatively dense and provides some resistance to air flow,
not all air leaving the indirect stage passes through the direct
stage into the conditioned space. About twenty percent (20%) of the
air exiting the dry passages of the indirect stage is deflected
back into the parallel wet passages of the indirect stage to
promote evaporative cooling. After passing over the surfaces of the
wet passages, the air exits the IDEC into the outside air as an
exhaust gas, typically at a temperature of about 80.degree. F.
[0018] As described in Davis II a rotationally molded outer housing
or cabinet is preferably used to contain all components of the
IDEC, including blower, indirect and direct cooling stages, and
sump that holds water that is pumped to the manifold. This outer
cabinet is rigid with its front opening (conditioned space side)
designed to hold the front face of the direct cooling stage
described above. Immediately behind this section is the indirect
cooling stage containing the folded plates also described above. It
is important that these indirect and direct stages be serviceable,
i.e., removable from the cabinet because they sometimes get fouled
with water minerals or otherwise lose their capacity to cool air.
Applicant's arrangement of plates facilitates this serviceability
by providing structural integrity for groups of plates in the
indirect cooling stage. More specifically, the aforementioned
rigid, preferably stainless steel, clamps at the top of the
indirect cooling plates, plus the relatively rigid material used in
the plates, preferably PVC, provide a structural backbone for the
plates that holds them in a semi-rigid state that facilitates their
insertion, removal and replacement in the cabinet.
[0019] Applicants' apparatus also solves another problem with prior
art IDECs, namely, potential overflow and flooding problems. IDECs
can be located in attics or furnished spaces of residences. If the
sump in the bottom of the IDEC overflows, water damage to the
underlying residential space may occur. To prevent this from
occurring applicants' IDEC has an emergency overflow drain and
shutoff switch, if and when, water rises to an overflow level in
the sump.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic drawing showing the overall system for
powering the claimed evaporative cooling system from a sustainable
energy source.
[0021] FIG. 2 is an isometric view of the molded cabinet containing
components of the evaporative cooling system.
[0022] FIG. 3 is a schematic design of the electrical interconnects
providing seamless supply of power from multiple power sources.
[0023] FIG. 4 is a schematic top plan view showing a water
distribution manifold supplying water to the indirect and direct
evaporative cooling stages of the IDEC system.
[0024] FIG. 5 is a perspective view of an array of indirect
evaporation cooling plates and the air flow therethrough.
[0025] FIG. 6 is a side elevational view of the indirect
evaporative cooling plates of the invention.
[0026] FIG. 7 is a top plan view of several assembled indirect
evaporative cooling plates.
[0027] FIG. 8 is a fragmental cross sectional view in elevation
taken along line 8-8 of FIG. 6.
[0028] FIG. 9 is top plan view of the water distribution manifold
of this invention.
[0029] FIG. 10 is a cross sectional end view taken along lines
10-10 of FIG. 9.
[0030] FIG. 11 is a front elevational view showing the coated water
contact (wet) surface of a typical indirect evaporative cooling
plate.
[0031] FIG. 12 is a front elevational view of the uncoated (dry)
surface of a typical indirect evaporative cooling plate.
DETAILED DESCRIPTION OF THE INVENTION
[0032] The basic components of applicants' IDEC 10 are
schematically illustrated in FIG. 1. These components are
preferably housed in a cabinet 12 which is molded as a single
plastic part as shown in FIG. 2. This one piece plastic
construction of the cabinet 12 promotes ease of manufacture and
reduces corrosion issues as noted in Davis II. This approach also
facilitates assembly and replacement of parts in the cabinet of
12.
[0033] For simplicity sake, the arrangement and function of basic
sections of the cabinet 12 will be described in a top-to-bottom
sequence. The upper end 14 (as viewed in FIG. 1) of the cabinet 12
has a volute shape with a generally circular outside air inlet 16
and a larger, generally rectangular air outlet discharge 18. The
air outlet discharge 18 transitions into the larger, generally
rectangular cross-sectional body 20 of cabinet 12. A reservoir
chamber 22 at the bottom of cabinet 12 rounds out the basic
sections of the cabinet 12, which is preferably formed as a
rotationally molded product.
[0034] To enhance structural integrity of cabinet 12, it should be
molded with structural ribs 26 in a manner known to those skilled
in the art (See FIG. 2). This structural integrity is preferably
built into the sides 28, 30 and top 32 of cabinet body 20 as
illustrated in FIG. 2. The front 34 of cabinet 12 through which
conditioned air passes and rear 36 of cabinet body 20 through which
exhaust air passes are essentially open to discharge these air
flows from the cabinet 12 (See FIG. 2). In addition, expanded area
37 of body 20 is formed into the top 32 of body 20 of cabinet 12 to
facilitate introduction of water. Ribs 38 on the inside of cabinet
body 20 can also be molded into cabinet 12 to support the cooling
plates as discussed in more detail below.
[0035] As shown in FIG. 1, fan motor 40 is mounted within upper end
14 of cabinet 12. More particularly, brackets 42 attached to the
air inlet 16 of the upper end 14 of cabinet 20 are used to mount a
fan in spaced relationship to the periphery of air inlet 16. A
squirrel cage blower or fan 41 is mounted on the shaft of motor 40
in a known manner to draw outside air through air inlet 16 and
force it through air discharge 18 into the body 20 of cabinet 12.
Fan Motor 40 operates at variable speeds that are selected to meet
the variable cooling loads experienced by a user of the IDEC 10. A
preferred motor 40 for use in applicant's system is an
electronically-commutated motor (ECM) which enables variable speed
operation at high efficiency. ECMs are essentially parallel-wound
direct current (DC) motors that can make efficient use of electric
energy from both DC and AC power sources.
[0036] The motor 40 having particular application in this invention
is one that can selectively use DC power, for example, from a
photovoltaic (PV) source such as a solar panel, and/or AC power
supplied from a utility's power grid. In this way, power can be
supplied to the motor 40 based on its availability. Since
availability of PV energy is likely to be at a maximum on the
hottest, sunniest days of the year when utilities are working to
meet peak demand, the disclosed system can be run by PV power
without adding to that peak demand.
[0037] ECM fan motors 40 found to have these desired system
operating characteristics are sold by General Electric Company as
the "GE ECM 2.3 series". Details of their operation are provided at
www.geindustrial.com/cwc/products? Some operational features are
also shown in U.S. Pat. No. 4,757,241 issued Jul. 12, 1988.
[0038] Since the ECM motor of choice basically operates on direct
current (DC) its use, without adaptation, would not be particularly
useful in the claimed system which is operated from both AC and DC
sources and combinations of such sources. Accordingly, applicants
have connected the ECM motor to both sources through the diode
interconnect box 44 illustrated in FIGS. 1 and 3. As shown in FIG.
1, DC power from a sustainable power source, for example, a solar
panel, and AC power from a utility power grid are fed to the diode
interconnect box 44 and power from that box is fed to fan motor
40.
[0039] The diode interconnection of these power sources with fan
motor 40 is schematically illustrated in FIG. 3. AC power 46 from
the grid is fed to terminal block 48 within box 44 which in turn is
electrically connected to a diode bridge 50 which rectifies the AC
input into positive and negative DC power. That DC power is fed
over lines 52, 54, respectively, to the ECM motor through terminal
block 56 in diode interconnect box 44. DC power from, for example,
an array of PV solar cells, is fed via lines 58, 60 to terminal
block 62 to a second diode bridge 64. The positive DC output of
bridge 64 is fed by line 66 to line 52 containing the positive DC
output exiting diode bridge 50. The negative DC output line 68 from
diode bridge 64 is fed to line 54 carrying the negative output of
diode bridge 50. This unique use of diodes avoids many of the
problems with inverters used to control power from AC and DC
sources such as the system disclosed in U.S. Pat. No. 4,697,136
described above.
[0040] As previously noted, the cooling efficiency of any IDEC is
related to the amount of evaporation that occurs within it. Degree
of evaporation, in turn, is a function of the amount of water
evaporated. That depends to a large measure on the amount and area
of water available for evaporation. In applicant's IDEC, these twin
goals for improved evaporation are achieved in part with heat
exchange plates 70 having a unique configuration, coating and
clamping. The plates 70 can be formed in a thermoforming process
that processes a roll of plastic material, preferably
polyvinylchloride (PVC). The plates 70 are thermoformed with
various surface features which facilitate their assembly into an
indirect cooling section 72 of IDEC 10. Preferably, the plates are
formed as pairs about vertical centerlines 74. The plates are
folded along these centerlines 74 to form a folded edge 76 that
eliminates the need to seal that back edge (FIG. 5). Other features
formed in the plastic heat exchange sheets 70 include spacers 78
that keep the individual sides of each plate pair separated to
facilitate passage of air between plates. The front edge 80 of the
plate pairs have interlocking snaps 82 that fasten the open edge 80
of the plate pairs in a spaced parallel orientation one to the
other. Other snaps 82 strategically placed throughout the plate 70
help to maintain the structural integrity of the plate pairs when
folded (See FIG. 6).
[0041] Also formed in the plates are air diverters 84 and 86 that
act as air foils directing air exiting from the air discharge area
18 throughout the area within the dry passages. The bottom edge of
the plates contain thermoformed ridges 88 that align with each
other to form a barrier to air, but not water, passage out of the
bottom of plates 70.
[0042] After thermoforming the plates 70 with the various
centerlines, diverters and snaps just described, the side of plate
70 that is exposed to water (the "wet" side) is coated with a
hydrophilic material. While some suppliers of IDEC's, for example
Adobe Air, Inc. mentioned above, have used hydrophilic material
such as polyester in the indirect cooling sections of their IDECs,
these materials have been found deficient for a variety of reasons.
Some of these materials, for instance, have a tendency to foam when
wetted which reduces effectiveness. Others have not shown the
durability needed to operate over long periods of time. Applicants
have found a hydrophilic material 89 having substantially improved
wetting and durability characteristics for use in IDEC's. This
material is a flocked rayon material sold by Flock Tex Incorporated
of Woonsocket, R.I. (www.flocktex.com) under the Flock Tex
tradename. The Flock Tex material used as the hydrophilic layer 89
on plates 70 is a random cut rayon with an approximate length of
0.020 inches and pile height of 0.005 inches. It has a density of
about 1.3 ounces per square yard when applied to plates 70. It is
affixed to heat exchange plate 70 with an adhesive such as a vinyl
acetate momoner.
[0043] The flocked rayon coated plates 70, forming the indirect
cooling section 72, as mentioned above, are assembled in pairs
around centerlines 74 so that the back edge 76 is closed and the
front edges 80 are open. The thermoformed ridges 88 in the bottom
of the plate pairs 70 are turned toward each other to block air
flow out of the dry side of the plates, thereby assuring that
substantially all air from fan 40 will pass out the front end of
the plate pairs in a manner described herein. On the wet side of
the plates, there is no corresponding ridge 88 and the water on
that side of plates 70 flows by gravity into reservoir 22.
[0044] FIG. 5 is a perspective view of the indirect heat exchange
plates showing both air and water flow patterns according to a
preferred embodiment of the present invention. The indirect cooling
section 72 uses parallel heat exchange plates 70 to separate dry
passages 92 and wet passages 94. The entering airstream travels
vertically downward as it leaves the air discharge area 18 and
enters the dry passages 92 along their top back zone, where it is
collectively referred to as airstream 96 that divides among the dry
passages 92. The heat exchange plates 70 are shaped such that the
wet passages 94 are closed where they face the air discharge area
18 so that air leaving the fan blower 40 does not directly enter
the wet passages 94. Airstream 98 within the plates 70 is assisted
in its movement therethrough by air diverters 84 and 86. Upon
exiting the dry passages 92, airstream 98 divides into two air
streams. Airstream 100 continues in the same direction as airstream
98 and enters the direct cooling stage 110, the other airstream 104
turns 180.degree. and enters the wet passages 94.
[0045] The water distribution route through wet passages 94 is
illustrated in FIGS. 1 and 4. Water is introduced to the reservoir
22 via a fill valve 112 that may be electronically controlled based
on the position of a float switch 114. A pump 116 circulates water
from the reservoir 22 through a distribution pipe 118 to the top of
the unit, whereupon water enters a distribution manifold 120 that
apportions water to both the indirect cooling section 72 and the
direct cooling section 110 of IDEC 10. Water that is not evaporated
flows downward by gravity through both stages and then back to the
water reservoir 22. In the process it distributes water through the
direct cooling stage 110 and the surfaces of the wet passages 94 of
the indirect cooling section 72. Water in the indirect cooling
section 72 and the direct cooling section 110 is evaporated by
airstreams forced by fan blower 40. Water from the pump 116 is
continuously recirculated during IDEC operation.
[0046] As noted above, several approaches to water distribution in
IDECs have been proposed. Each one has drawbacks because the
distribution is not uniform across the entire width of the indirect
cooling section 72. Applicants have overcome this problem by
fabricating their manifold 120 from a unique porous material made
by Porex Corporation. As noted above, this material uniformly
"sweats" or passes water through its perimeter thus providing
uniform water distribution over the length of the manifold. As
illustrated in FIGS. 4, 9-10, the manifold 120 preferably has a
central inlet 122 which supplies an "H"-shaped fixture that is
hydraulically linked to two branches, one of which 124 extends
above the direct cooling section 110 of the IDEC 10 and the other
126 above the indirect cooling section 72 of the IDEC 10. Both
branches 124, 126 of manifold 120 are preferably made of POREX.RTM.
S40C tubing. This tubing is a sintered, high density polyethylene
material with a porous structure and is available in a wide variety
of sizes and shapes. Porex also offers porous fittings for use with
this tubing, such as end caps and supply fittings 122, thereby
insuring complete uniformity of water distribution across the
entire width of the indirect 72 and direct 110 evaporative cooling
sections.
[0047] FIGS. 5-7 show the top edges of the indirect cooling section
72 and show in detail dry passage inlets 93 and wet passage inlets
95. The dry passage inlets 93 are located beneath the air discharge
area 18 of cabinet 12 and the heat exchange plates 70 taper toward
one another to close the wet passages to prevent air leaving from
blower 40 from entering the wet passages 94. Openings to the wet
passages 95 are located beneath branch 126 of the distribution
manifold 120. Water leaving the manifold 120 enters the wet passage
inlets 95. Directly beneath each wet passage inlet 95 is a
horizontal trough 130 extending above the entire width of each
plate 70 and spanning between each pair of heat exchange plates
facing the wet passages 94. Vertical barrier segments 132 prevent
water from spilling out the ends of the troughs 130. The bottom 134
of trough 130 is designed such that, with sufficient water supply
from manifold 120, water will flow the width of each wet passage
94. In one preferred embodiment, each trough 130 is formed by
mating "mirror-image" troughs projecting from adjacent plate
surfaces. These troughs 130 are formed as part of the
thermo-forming process as described above.
[0048] One aspect of this invention is the separation of air from
water within the indirect cooling section 72. To achieve this
separation, the folded heat exchange plate pairs 70 are assembled
into an array 140 of multiple plates, a few of which are
illustrated in FIG. 7 in top plan view. A typical IDEC 10 having a
2-3 ton cooling capacity and utilizing the features disclosed
herein would have about 45-50 plate pairs 70. Those plate pairs can
be readily inserted in the rear 36 of cabinet body 20 and supported
on a perforated base 141 which in turn is supported therein by ribs
38 in that housing (FIG. 2). Removal of plates 70 for repair or
replacement is a simple matter of compressing the array 140 of
plates 70 and sliding it out of the rear 36 of cabinet body 20.
[0049] As previously discussed, air flow 96 from fan 40 must be
directed to the dry side of plates 70 whereas water must be
directed to the wet side of plates 70 containing the hydrophilic
material 89. This separation occurs at the top edge 142 of the
plate array 140. More particularly, adjoining plate pairs 70
created by folding the thermoformed plastic along centerline 74 are
clamped along the top edge 142 of the array. The clamping material
found best suited to this application is a bendable strip of
hardened stainless steel or aluminum. These clamps are used in two
different locations along the top edge 142 of array 140. One clamp
144 is located under the air discharge area 18 of cabinet 12 and
the other clamping strip 146 is located beneath the water manifold
pipe 126 (See FIGS. 6-7). Clamping strip 144 clamps adjoining plate
pairs 70 as shown in FIGS. 5, 7 to open air flow into the dry
passage 92 between the dry sides 149 of plates 70. Clamping strips
146 close that passage and force water flowing from manifold pipe
126 into wet passages 94 on the side of plates 70 containing the
hydrophilic material 89.
[0050] The porous tubing 126 of manifold 120 is preferably oriented
so that it touches clamp 146 as illustrated in FIG. 8. This contact
promotes the flow of water from porous tubing 126 at the point of
contact. This flow increases the supply of water directly onto the
wet side 89 of plates 70 and then into wet passages 94. FIG. 8 is a
cross sectional view of an upper portion of plates 70 illustrating
water and air flow through the array 140.
[0051] The direct cooling section 110 of IDEC 10 is located near
the front 34 of cabinet body 20. It comprises an evaporative medium
made from fluted sheets of a cellulosic paper, the flutes of one
sheet being arranged at an angle to the next sheet. The cellulosic
paper is typically treated with a preservative. An example of
commercially available treated cellulosic cross-fluted paper is
that produced by Munters Corporation of Ft. Myers, Fla. under the
Trademark CELdek.RTM. (www.munters.com). This material is described
in more detail in U.S. Pat. Nos. 4,562,015 and 4,427,607, the
disclosures of which are incorporated by reference herein. Water is
supplied to the direct cooling section by water manifold 124. As in
the indirect stage, the manifold is preferably in direct contact
with the evaporative medium in the direct stage.
[0052] A problem associated with operation of IDEC's is
contamination of the water recirculated through the unit. This is
overcome in applicants' unit by having a periodic purge cycle
programmed into the operational controls of the unit. On a
preprogrammed cycle purge pump 150 is activated to empty the
reservoir 22 to a drain. The reservoir 22 is then refilled with
fresh water through valve 112. Another problem associated with
IDEC's is leakage in the rare instance when the reservoir 22
overflows. Since many IDEC's are located in the attics of homes,
such overflows can cause real damage. This problem is obviated in
applicants IDEC 40 by placing a drain outlet 152 at a high point in
the reservoir. The drain outlet 152 can be piped to a sewer or to
the outside where it can be put to good use watering vegetation.
The operational controls of the IDEC unit can be programmed to shut
down the system and sound an alarm if there is flow from the drain
outlet 152 over an extended period of time which would suggest a
malfunction. This alerts users of the IDEC to perform whatever
service is needed to correct that malfunction.
[0053] To simplify operation and reduce cost purge pump 150, fill
valve 112, circulation, pump 116 and operational controls (not
shown) can be operated from grid power as shown in FIG. 1.
* * * * *
References