U.S. patent application number 10/963188 was filed with the patent office on 2005-04-14 for cooling assembly.
Invention is credited to Pruitt, Roger.
Application Number | 20050076665 10/963188 |
Document ID | / |
Family ID | 32073271 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050076665 |
Kind Code |
A1 |
Pruitt, Roger |
April 14, 2005 |
Cooling assembly
Abstract
A process and the required apparatus for air conditioning the
interior of a structure is shown which can be run entirely off a DC
power source, such as a storage battery. A shell and tube heat
exchanger is combined with a mechanical refrigeration system to
provide a wet shell side and a dry tube side of the apparatus. In
the operation of the air conditioner, a mass of distributed water
is established on the wet shell side, and a flow of ambient air is
passed through the wet shell side to form a resulting stream of
moist air. A flow of ambient air is passed through the dry tube
side and a resulting stream of dry cooled air is recovered. The
streams of most and cooled air can either be combined or routed
separately depending primarily upon the humidity of the surrounding
environment to be cooled. The air conditioning unit is not
hermetically sealed and the water consumption rate is generally
less than that required for a conventional evaporative cooler.
Inventors: |
Pruitt, Roger; (Banning,
CA) |
Correspondence
Address: |
Charles D. Gunter, Jr.
Whitaker, Chalk, Swindle & Sawyer, LLP
3500 City Center Tower II
301 Commerce Street
Fort Worth
TX
76102-4186
US
|
Family ID: |
32073271 |
Appl. No.: |
10/963188 |
Filed: |
October 12, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10963188 |
Oct 12, 2004 |
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10629121 |
Jul 28, 2003 |
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60405584 |
Aug 23, 2002 |
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Current U.S.
Class: |
62/310 ;
62/314 |
Current CPC
Class: |
F28D 7/1653 20130101;
F24F 6/043 20130101; Y02B 30/54 20130101; F24F 1/0071 20190201;
F24F 5/0035 20130101; F28D 5/00 20130101; F24F 1/0007 20130101 |
Class at
Publication: |
062/310 ;
062/314 |
International
Class: |
F28D 005/00 |
Claims
What is claimed is:
1. A cooling assembly comprising: a heat exchanger, said heat
exchanger including a case member enclosing a wet side in heat
exchange relationship with a dry side, said sides being
substantially hermetically sealed from one another; a first air
moving member adapted to move air through said dry side to produce
a cooled stream of air; a liquid distributing member within said
wet side; a liquid sump element associated with said wet side and
adapted to receive liquid from said wet side and to make said
liquid available to said liquid distributing member; at least two
additional air moving members adapted to move air through said wet
side from different locations to produce a humidified mass of
turbulent air on said wet side; a mechanical refrigeration unit
including a compressor and an associated refrigeration manifold,
the refrigeration manifold being located within the liquid sump
element for refrigerating liquid contained therein; and an exhaust
duct for conveying cooled air from the dry side of the assembly to
the interior of a structure to be cooled.
2. The cooling assembly of claim 1, including an additional conduit
which combines the cooled air from the dry side of the assembly
with the turbulent air from the wet side and delivers the resultant
combined streams to the interior of a structure.
3. The cooling assembly of claim 1, further comprising a DC power
source for powering the first and additional air moving members,
the DC power source including one or more storage batteries.
4. The cooling assembly of claim 3, further comprising an ambient
energy harvesting system operatively associated with the storage
batteries for charging the storage batteries.
5. The cooling assembly of claim 3, wherein the DC power source
supplies all of the power needs for the cooling assembly.
6. The cooling assembly of claim 4, further comprising an
electrical inverter which allows the storage batteries to be
charged by an AC power source.
7. The cooling assembly of claim 4, wherein the ambient energy
harvesting system includes at least one solar cell.
8. A cooling assembly for cooling the interior of a structure, the
assembly comprising: a heat exchanger, said heat exchanger having a
shell side and a tube side; a first air moving member adapted to
move air through said tube side to produce a cooled, relatively dry
stream of air; a liquid dispensing member on said shell side
adapted to distribute liquid substantially throughout said shell
side; a liquid sump element associated with said shell side and
adapted to receive said liquid from said shell side and to make
said liquid available to said liquid dispensing member; a plurality
of air moving members adapted to move air through said shell side
from different directions to produce a turbulent mass of air on
said shell side; a mechanical refrigeration unit including a
compressor and an associated refrigeration manifold, the
refrigeration manifold being located within the liquid sump element
for refrigerating liquid contained therein; and an exhaust duct for
conveying cooled air from the dry side of the assembly to the
interior of a structure to be cooled.
9. The cooling assembly of claim 8, wherein the tube and shell side
air moving members all require electrical power for their
operation, the cooling assembly further comprising a battery
system, the battery system being adapted to supplying all of the
required electrical power for operation of the assembly; and a
solar cell system chargingly associated with the battery
system.
10. The cooling assembly of claim 8, further comprising: a water
supply system associated with the liquid sump and liquid dispensing
member on the shell side of the assembly, the water supply system
including a water pump positioned between the liquid sump and the
liquid dispensing member for maintaining the shell side of the
assembly wet with water.
11. A cooling assembly for cooling the interior of a structure, the
cooling assembly comprising: a stacked chamber arrangement having a
centrally located, forced-air evaporative cooling chamber which
separates an exhaust air plenum located above the cooling chamber
from an air intake plenum located below the cooling chamber, the
cooling chamber having a top wall and a bottom wall and surrounding
sidewalls and a plurality of vertically arranged riser tubes which
connect the intake plenum with the exhaust air plenum, the bottom
wall creating a cold water sump region; an intake fan, located
within the air intake plenum, for drawing air upwardly through the
plurality of vertical riser tubes which connect the intake plenum
with the exhaust air plenum to thereby produce a cooled stream of
air; a liquid distributing member located in the cooling chamber
adjacent the top wall thereof; a pump for pumping water from the
sump region of the cooling chamber to the liquid distributing
member; a pair of oppositely arranged fans mounted on the cooling
chamber sidewalls for moving air through the cooling chamber from
different locations to produce a humidified mass of turbulent air
within the cooling chamber; a mechanical refrigeration unit
including a compressor and an associated refrigeration manifold,
the refrigeration manifold being located within the sump region of
the cooling chamber for refrigerating water contained therein; and
an exhaust duct for conveying cooled air from the exhaust plenum of
the assembly to the interior of a structure to be cooled.
12. The cooling assembly of claim 11, wherein the oppositely
arranged fans on the cooling chamber sidewalls are mounted over
louvers, the louvers being adjustable to direct air in a circular
vortex within the cooling chamber, thereby contributing to the
turbulence of the air within the cooling chamber.
13. The cooling assembly of claim 11, wherein the vertically
arranged riser tubes located within the cooling chamber are copper
tubes which are less than about 1/2 inch in diameter.
14. The cooling assembly of claim 13, wherein the vertically
arranged riser tubes are in the range from about 1/4 to {fraction
(3/8)} inches in diameter.
15. The cooling assembly of claim 11, wherein the refrigeration
manifold is a double stock manifold having a front coil layer and a
rear coil layer, the front and rear coil layers being spaced apart
by means of a plurality of cylindrical spacers.
16. The cooling assembly of claim 15, wherein the cylindrical
spacers are less wide than the total width of the manifold, leaving
a distance between adjacent spacers, and wherein the cylindrical
spacers are also hollow and open at both ends, allowing water in
the sump region to flow around and through the spacers.
17. The cooling assembly of claim 16, wherein the double manifold
is arranged in a generally horizontal plane within the sump region
and wherein the front and rear coil layers of the double manifold
contain a pair of flow path splits which act to distribute
refrigerant which is communicated from the compressor to the
coils.
18. A direct/indirect evaporative cooling assembly with
refrigerated chilled water sump for cooling the interior of a
structure, the cooling assembly comprising: a stacked chamber
arrangement having a centrally located, forced-air evaporative
cooling chamber which separates an exhaust air plenum located above
the cooling chamber from an air intake plenum located below the
cooling chamber, the cooling chamber, intake plenum and exhaust
plenum comprising a shell and tube heat exchanger which encloses a
wet side in heat exchange relationship with a dry side, the sides
being substantially hermetically sealed from one another; the
cooling chamber having a top wall and a bottom wall and surrounding
sidewalls and a plurality of vertically arranged riser tubes, the
bottom wall creating a cold water sump region as well as the top
wall of the air intake plenum and a lower tubesheet for the riser
tubes, the top wall of the cooling chamber forming the bottom wall
of the exhaust air plenum and an upper tubesheet for the riser
tubes; an intake fan, located within the air intake plenum, for
drawing air upwardly through the plurality of vertical riser tubes
which connect the intake plenum with the exhaust air plenum to
thereby produce a cooled stream of air from the dry side of the
assembly; a liquid distributing member located on the wet side of
the cooling chamber adjacent the top wall thereof; a pump for
pumping water from the sump region of the cooling chamber to the
liquid distributing member; a pair of oppositely arranged fans
mounted on the cooling chamber sidewalls for moving air through the
wet side from different locations to produce a humidified mass of
turbulent air on the wet side; a mechanical refrigeration unit
including a compressor and an associated refrigeration manifold,
the refrigeration manifold being located within the sump region of
the cooling chamber for refrigerating water contained therein; and
an exhaust duct for conveying cooled air from the dry side of the
assembly to the interior of a structure to be cooled.
19. The cooling assembly of claim 18, including an additional
conduit which combines the cooled air from the dry side of the
assembly with the turbulent air from the wet side and delivers the
resultant combined streams to the interior of a structure.
20. The cooling assembly of claim 18, further comprising a DC power
source for powering the intake and additionally arranged fans, the
DC power source including one or more storage batteries.
21. The cooling assembly of claim 20, further comprising an ambient
energy harvesting system operatively associated with the storage
batteries for charging the storage batteries.
22. The cooling assembly of claim 20, wherein the DC power source
supplies all of the power needs for the cooling assembly.
23. The cooling assembly of claim 18, further comprising an
electrical inverter which allows the storage batteries to be
charged by an AC power source.
24. The cooling assembly of claim 21, wherein the ambient energy
harvesting system includes at least one solar cell.
25. The cooling assembly of claim 18, wherein the refrigeration
compressor is a DC compressor which is located in a storage area on
top of the exhaust plenum of the assembly.
26. The cooling assembly of claim 18, wherein the liquid
distributing member includes a distribution header located in the
cooling chamber adjacent the top wall thereof, and wherein the
cooling chamber further includes pads of evaporative media arranged
in the chamber between the vertical riser tubes to surround and
contact the tubes, whereby cold water is introduced from the sump
region of the cooling chamber and pumped through the distribution
header onto the evaporative media to thereby cool the riser tubes
in the cooling chamber.
27. The cooling assembly of claim 18, wherein the compressor and
refrigeration manifold are operated to cool the water in the sump
region to near freezing temperature.
28. The cooling assembly of claim 18, wherein an electrical
inverter is located within the exhaust plenum of the assembly which
allows the unit to be operated off AC current, the location of the
inverter within the chilled exhaust plenum serving to prolong its
useful life by lowering its operating temperature.
29. A cooling assembly for cooling the interior of a structure, the
cooling assembly comprising: a stacked chamber arrangement having a
centrally located, forced-air evaporative cooling chamber which
separates an exhaust air plenum located above the cooling chamber
from an air intake plenum located below the cooling chamber, the
cooling chamber having a top wall and a bottom wall and surrounding
sidewalls and a plurality of vertically arranged riser tubes which
connect the intake plenum with the exhaust air plenum, the bottom
wall creating a cold water sump region; an intake fan, located
within the air intake plenum, for drawing air upwardly through the
plurality of vertical riser tubes which connect the intake plenum
with the exhaust air plenum to thereby produce a cooled stream of
air; a liquid distributing member located in the cooling chamber
adjacent the top wall thereof; a pump for pumping water from the
sump region of the cooling chamber to the liquid distributing
member; an evaporative media located in the cooling chamber
surrounding and contacting the vertical riser tubes, the
evaporative media being wet by water pumped through the liquid
distributing member; a pair of oppositely arranged fans mounted on
the cooling chamber sidewalls for moving air through the cooling
chamber from different locations to produce a humidified mass of
turbulent air within the cooling chamber; a mechanical
refrigeration unit including a compressor and an associated
refrigeration manifold, the refrigeration manifold being located
within the sump region of the cooling chamber for refrigerating
water contained therein; an exhaust duct for conveying cooled air
from the exhaust plenum of the assembly to the interior of a
structure to be cooled; wherein the cooling chamber has a pair of
auxiliary refrigeration jacks which comprise an inlet and outlet
point for chilled water in the sump region of the assembly; and
wherein the auxiliary refrigeration jacks are connected by a
suitable conduit to an auxiliary heat exchange device located at a
remote location within the structure to be cooled.
30. The cooling assembly of claim 29, wherein the auxiliary heat
exchange device is a housing containing a fluid pump, a heat
exchange coil and a fan, water from the cold water sump of the
cooling assembly being pumped through the coil and circulated back
to the sump, the fan creating an exhaust air flow over the coil to
provide additional cooling to the structure.
31. The cooling assembly of claim 30, wherein the pump and fan both
operate off DC power, and wherein the conduit which connects the
auxiliary heat exchange device to the cooling assembly also has
associated therewith a power line for supplying DC current from the
main cooling unit to the auxiliary heat exchange device.
32. The cooling assembly of claim 31, wherein the inlet and outlet
water conduits and DC power line are all contained within a common
sheath which is run from the main cooling assembly to the auxiliary
heat exchange device.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of my earlier
filed application Ser. No. 10/629,121, filed Jul. 28, 2003, and
which claimed the benefit of U.S. Provisional Application No.
60/405,584, filed Aug. 23, 2002.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates in general to low power air
conditioning systems, and, in particular, to a low power air
conditioning system employing a tube and shell heat exchanger for
use in arid conditions and to a combination direct/indirect
evaporative cooler with refrigerated sump water for use in other
environments.
[0004] 2. Description of the Prior Art
[0005] In one embodiment, the present invention provides air
conditioning for structures that are located in arid, high
temperature environments, such as deserts. Such environmental
control is essential to enjoying a good quality of life, and, in
some instances, is essential to supporting life. This is true for
both humans and livestock.
[0006] In desert environments, daytime temperatures often reach
well above 100 degrees Fahrenheit while at the same time the
relative humidity is often below 20 percent. Typically,
conventional evaporative cooling based air conditioning systems, so
called "swamp coolers", are effective in such conditions, because
of the low humidity. A source of electrical power is required to
operate such systems, so the cost of operation is a limitation on
their use. Conventional evaporative coolers consume considerable
quantities of water so their use is limited to areas where water is
available. Sufficient quantities of water are not always available
in desert environments. Other types of air conditioning systems
require sealed buildings, expensive and high maintenance equipment,
and are expensive to operate. Some dwellings and particularly
buildings in which livestock may be kept are not well sealed or
insulated so there is little impediment to the interiors of such
structures reaching thermal equilibrium with the exterior
environment. Typically, such structures are not provided with air
conditioning systems because of the cost of operating them and the
general ineffectiveness of air conditioning systems in such
structures. Most air conditioning systems operate on electricity,
and electricity is not always available, or is not available at a
reasonable price where the structures are located. It would be
greatly beneficial to both human beings and livestock if an
effective, simple, self-contained air conditioning system could be
provided for desert environments that would operate inexpensively
in unsealed structures.
[0007] It would also be advantageous to provide an air conditioning
system which could be powered on direct current, either by
batteries or solar panels, or both, which system had the previously
described advantages while at the same time being operable over
wider humidity ranges including tropical and semi-tropical
climates.
[0008] It would be a further advantage to provide such a system
which utilized both a relatively wet airstream and a relatively dry
airstream, which airstreams could be selectively routed to the
interior of a structure to be cooled, either by combining the
streams in a predetermined ratio or by selecting, for example, only
the relatively dry airstream to be delivered to the space to be
cooled in the presence of high humidity.
[0009] In its simplest form evaporative cooling of buildings has
been accomplished by injecting a fog or mist of water into a moving
stream of air. See, for example, Atkins, U.S. Pat. No. 5,146,762.
One problem with this system is that it causes excess humidity
within the building resulting in algae and bacteria problems.
Atkins proposes to minimize some of these problems by placing
exhaust fans at one end of a building widely spaced from fogger
nozzles at the opposite end of the building. The disclosed rate of
water consumption is very high. In excess of 95 percent of the
water supplied to the fogger nozzles is consumed. Atkins'
evaporative cooling system is said to produce a temperature drop of
approximately 20 degrees.
[0010] Conventional evaporative cooling systems have been combined
into more elaborate systems that include heating means. See, for
example, Grant et al. U.S. Pat. No. 4,773,471. Conventional
evaporative cooling systems have also been combined into elaborate
systems with refrigerated air systems. See, for example, Conner
U.S. Pat. No. 5,911,745.
[0011] Urch U.S. Pat. No. 6,434,963 discloses an air cooler with
two air flow paths, namely, an inlet path for outside air and an
outlet path for stale air. A heat exchanger pre-cools the fresh air
with heat extracted from the stale air, and further cooling is
achieved by means of an evaporative cooler that spans the two air
flow paths.
[0012] Those concerned with these problems recognize the need for
an improved air conditioning system.
SUMMARY OF THE INVENTION
[0013] In one embodiment, the air conditioning assembly according
to the present invention comprises a shell and tube heat exchanger
wherein ambient air is forced through both sides and discharged
approximately together into the interior of the structure that is
to be cooled. For convenience, the air streams from the two sides
can be combined into one combined stream before being discharged
into the interior of the structure, or they may be discharged
separately into the structure. This heat exchanger is particularly
suited for use in the high heat and low humidity conditions that
are typically found during the summer months in deserts. The air
conditioning assembly is particularly effective in situations where
the temperature is above approximately 80 degrees Fahrenheit, and
the relative humidity is below approximately 40 percent, and,
preferably, below approximately 35 percent. The assembly is
suitably operable even in situations where the structure to be air
conditioned is not tightly sealed, that is where there may be
openings through the structure that are substantially unobstructed
to air flow having as much as, for example, six square inches to a
square foot or two of area. Barns, tents, temporary structures and
the like are provided with an efficient, reliable, economical,
simple, and effective air conditioning system according to the
present invention. The air conditioning system according to the
present invention does not require an elaborate or expensive
installation for its functioning. It can be easily transported to
and set up inside of a temporary structure such as, for example, a
tent.
[0014] The shell side of the heat exchanger is preferably wet with
a shower or weep of a liquid such as water, and the air flow is
turbulent through the shell side. The stream of flowing air is
directed from the shell side to an outlet. The air flowing through
the tube side is cooled by contact with the walls of the tubes, and
is discharged to an outlet. Preferably the air streams from the
shell and tube sides are combined and discharged into the interior
of the structure that is to be cooled. These air streams can be
combined after discharge into the interior of the structure, if
desired. Preferably, the intake and discharge of the air streams
are all within the interior of the structure.
[0015] In another embodiment, the present invention comprises a
direct/indirect evaporative cooler with refrigerated chilled sump
water. The cooler is preferably designed as a stacked arrangement.
A refrigeration compressor and storage batteries occupy a top
section of the design and rest on a top shelf. The top shelf forms
the top wall of an exhaust air plenum. A forced-air evaporative
cooling chamber, located below the exhaust air plenum, occupies the
middle section of the design and comprises about 65% of the total
height of the unit in one embodiment. A cold water sump and an
intake air plenum occupy the bottom floor of the cooling chamber.
The bottom floor of the cooling chamber also comprises the top wall
of an intake plenum which houses an intake fan. The intake fan
draws air upwardly through a plurality of riser tubes which connect
the intake plenum with the exhaust plenum and which pass through
the cooling chamber.
[0016] Water in the cold water sump is refrigerated by the
refrigeration compressor located in the top section of the design.
Cold water from the cold water sump is introduced into the
evaporative cooling chamber through a distribution header. The cold
water saturates an evaporative media which surrounds or otherwise
contacts the riser tubes in the cooling chamber. Air is introduced
into the cooling chamber by means of oppositely arranged fans
mounted on sidewalls of the cooling chamber which create a
turbulent air flow in the cooling chamber and which enhance the
evaporative cooling process. Cooled air from the cooling chamber
can be discharged through a suitable duct to the interior of the
structure to be cooled.
[0017] Air is also being drawn into the intake plenum by the intake
fan, which air flow is forced upwardly through the riser tubes in
the cooling chamber. The riser tubes pass though the cold water
sump and also contact the evaporative media in the cooling chamber,
whereby the outside of the tubes are cooled. The air within the
tubes is cooled by conduction through the tubes. This relatively
drier air can be directed through a suitable duct to the interior
of the structure to be cooled and can be combined with the more
moist, cooled air from the cooling chamber, if desired.
[0018] In this latter embodiment of the invention, air is being
cooled using two simultaneous processes. Air is cooled by direct
contact with water in the evaporative cooling chamber, raising the
absolute humidity of the air cooled in this manner. Additional air
is also being cooled by conductive heat transfer within the riser
tubes. The absolute humidity of this additional air is either
unchanged or only slightly changed, or decreases slightly, due to
condensation on the inside of the riser tubes. If desired, the two
air flows can be combined into a discharge duct so that the
discharged air consists of a mixture of relatively humid air from
the evaporative process and air with near ambient humidity. Control
over the humidity of the discharged air can be obtained by
regulating the ratio of the two previously described air flows.
[0019] The cold water sump at the bottom of the cooling chamber
serves as a cooling mass, as well as a water storage sump. The
water in the sump is refrigerated to near freezing by means of a
low temperature compressor similar to that used on an ice machine.
The compressor can be AC or DC operated, but is preferably DC
operated. The electric fans used in the intake plenum and on the
cooling chamber are preferably DC fans which can be driven by solar
cells or storage batteries.
[0020] Other objects, advantages, and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The present invention provides its benefits across a broad
spectrum of structures. While the description which follows
hereinafter is meant to be representative of a number of such
applications, it is not exhaustive. As those skilled in the art
will recognize, the basic methods and apparatus taught herein can
be readily adapted to many uses. It is applicant's intent that this
specification and the claims appended hereto be accorded a breadth
in keeping with the scope and spirit of the invention being
disclosed despite what might appear to be limiting language imposed
by the requirements of referring to the specific examples
disclosed.
[0022] Referring particularly to the drawings for the purposes of
illustration only and not limitation:
[0023] FIG. 1 is a diagrammatic view of one embodiment of a tube
and shell heat exchanger according to the present invention.
[0024] FIG. 2 is a cross-sectional view taken along line 2-2 In
FIG. 1.
[0025] FIG. 3 is a diagrammatic cross-sectional view taken through
the shell plenum of a further embodiment according to the present
invention showing a liquid spray system.
[0026] FIG. 4 is a diagrammatic cross-sectional view taken through
the shell plenum of a further embodiment according to the present
invention showing the tubes fully enclosed in blankets.
[0027] FIG. 5 is a plan view of a structure in which a tube and
shell heat exchanger air conditioning system according to the
present invention has been installed.
[0028] FIG. 6 is a cross-sectional view of the heat exchanger of
FIG. 5 taken through the shell plenum.
[0029] FIG. 7 is a chart of the temperature and relative humidity
readings recorded in Tables 4 and 5 at locations 116 and 120 in
FIG. 5.
[0030] FIG. 8 is a perspective view of another embodiment of the
device of the invention which features combined direct/indirect
evaporative cooling with refrigerated chilled sump water.
[0031] FIG. 9 is a rear view of the device of FIG. 8 with the rear
wall removed for ease of illustration of the internal components of
the device.
[0032] FIG. 10 is an isolated view of the cooling chamber and
refrigeration manifold used in the device of FIGS. 8 and 9.
[0033] FIG. 11 is a perspective view of the device of FIG. 8 with
the rear wall removed for ease of illustration of the internal
components of the device.
[0034] FIG. 12 is a view of the top wall of the cooling chamber
which also serves as a tube sheet for the riser tubes.
[0035] FIG. 13 is an isolated view of the cooling chamber of the
device of FIG. 8.
[0036] FIG. 14 is a side view of the cooling chamber showing the
location of the water distribution array.
[0037] FIG. 15 is an isolated view of the air intake plenum and air
intake fan.
[0038] FIG. 16 is an isolated view of the refrigeration manifold
used in the cold water sump of the device of FIG. 8.
[0039] FIG. 16A is a cross sectional view taken along lines 16A-16A
in FIG. 16.
[0040] FIG. 16B is a simplified end view of the manifold of FIG. 8
showing the cross-over piping arrangement used to produce the
interlayered flow pattern.
[0041] FIG. 17 is a simplified, schematic view of an auxiliary heat
exchange unit which can be operated off the chilled water in the
cold water sump of the device of the invention.
[0042] FIG. 18 is a cross-sectional view of a cable used to connect
the auxiliary heat exchange unit of FIG. 17 with the main cooling
assembly shown in FIGS. 8-15.
DETAILED DESCRIPTION OF THE INVENTION
[0043] The detailed description of the invention will now be
provided with respect to two different preferred embodiments:
[0044] Low Humidity Air Conditioner Embodiment:
[0045] Referring now to the drawings wherein like reference
numerals designate identical or corresponding parts throughout the
several views, there is illustrated generally at 10 a tube and
shell heat exchanger, which is particularly adapted for use as a
low power air conditioning unit in high temperature, low humidity
conditions with structures that are not hermetically sealed. The
floor plan of such a structure is indicated generally at 64 in FIG.
5.
[0046] Heat exchanger 10 is confined within external case 62. For
purposes of illustration, external case 62 is shown as rectangular,
but other arcuate, spherical, or cylindrical forms are contemplated
within the scope of the present invention.
[0047] Air, preferably internal air from near the ceiling of a
structure that is to be cooled, is drawn into the tube side of the
heat exchanger through inlet port 12 into intake plenum 14 of heat
exchanger 10. Air is drawn into inlet port 12 by exhaust fan 46.
Air is drawn from intake plenum 14 through heat exchange tubes 34
into exhaust plenum 18. Tube inlet ends 36 are sealingly mounted in
inlet tube sheet 60, and tube outlet ends 38 are sealingly mounted
in tube outlet sheet 32. Exhaust fan 46 expels the air from the
tube side of the heat exchanger into tube side exhaust conduit
22.
[0048] The shell side of heat exchanger 10 is in the form of a
shell plenum 16 that surrounds heat exchange tubes 34 between inlet
tube sheet 60 and outlet tube sheet 32. Heat exchange tubes 34 are
shown for the purposes of clarity of illustration as being
straight, but, as will be understood by those skilled in the art,
other forms such as coiled or looped heat exchange tubes can be
used. A body of liquid, preferably water, is disposed within the
shell side of heat exchanger 10. The surface of the body of liquid
is indicated at 50. The liquid generally occupies less than
one-half, and preferably, less than one-quarter of the volume of
the shell side of the heat exchanger. The bottom portion of the
shell plenum 16 forms a liquid sump in which the liquid resides. At
least one, and preferably at least two fans are position to force
ambient internal air from within the structure into shell plenum 16
of heat exchanger 10. In FIG. 1, three such shell side input fans
are indicated at 40 (first input fan), 42 (second input fan), and
44 (third input fan). These fans together generate substantial
turbulence in the air on the shell side of heat exchanger 10. The
air from shell plenum 16 is expelled from heat exchanger 10 through
shell side exhaust conduit 20.
[0049] The liquid in the sump within shell plenum 16 is sprayed
over the heat exchange tubes 34. One form of a spray system is
illustrated in FIG. 1, and consists of a pump feed line 26 that
serves to convey liquid from the liquid sump on the shell side to
liquid pump 24. Pump 24 supplies energy to the liquid and
discharges it through pump discharge line 28 to spray head 30 where
it is sprayed over the shell sides of heat exchange tubes 34. Spray
head 30 is typically located at or near the top of the shell side
plenum, although this is not necessary to the operation of the
system. It is schematically illustrated here on the side of the
shell side plenum for ease of illustration. The liquid runs and
falls back down into the sump where it is recycled again. The
liquid spray enhances the heat transfer between the heat exchange
tubes 34 and the liquid, as well as rapidly increasing the humidity
of the air in the shell plenum 16. Preferably, the liquid level is
automatically maintained at about a constant level by means of a
conventional float actuated valve connected to a supply of liquid
(not shown).
[0050] Heat transfer between the liquid and the heat exchange tubes
34 is further enhanced by the provision of blanketing members, for
example, tubular foam blankets 48 (FIG. 4), or loose reticulated
foam sheets 104 (FIG. 6) positioned in physical contact with the
heat exchange tubes 34. Also, the humidification of the air in
shell plenum 16 is enhanced by the presence of blanketing members
of some form. The blanketing members hold the liquid against the
heat exchange tubes 34, and increase the surface area of the liquid
within shell plenum 16. In general the blanketing members comprise
inert reticulated material through which liquid and vapor phase
liquids flow easily. Numerous such reticulated materials are known,
including, for example, many natural and synthetic open pore foams,
felts, battings, woven materials, and the like. Conventional
commercial swamp cooler pads are generally suitable for use as the
blanketing elements. Often such materials include bacteria stats,
fungi stats, and the like. The blanketing materials can completely
or partially enclose heat exchange tubes 34, as desired. Compare,
for example, FIGS. 4 and 6. For the sake of clarity of
illustration, these blanketing members are not illustrated in FIGS.
1, 2, and 3, but they are preferably employed in some form.
[0051] Various liquid spray systems can be employed. A particularly
effective system is illustrated particularly in FIG. 3. Liquid from
a suitable source such as, for example, the sump in shell plenum
16, is supplied under pressure to spray header 52 and distributed
to spray header branches 56. Liquid is expelled in a shower from
spray ports 54. Preferably, spray header 52 is positioned at the
normally upper end of shell plenum 16 adjacent to outlet tube sheet
32 so that liquid showers down over the heat exchange tubes 34 and
any associated blanket material, and is acted upon by the turbulent
air flow from the shell side fans 40, 42, and 44.
[0052] The air exhausted from the tube side through exhaust conduit
22 is preferably mixed with the air exhausted from the shell side
through exhaust conduit 20. The combined air streams are discharged
to the ambient interior of the structure that is being cooled
through combined exhaust conduit 58.
[0053] The best mode for the first embodiment of the invention
presently contemplated is illustrated particularly by reference to
FIGS. 5 and 6. An unfinished barn indicated generally at 64 has a
rectangular shape about 30 feet wide and 50 feet long. Barn 64 is
oriented east to west along its long axis as indicated by the
letters N, S, E, W, in FIG. 5. Barn 64 has an uninsulated peaked
metal roof, exposed 2 by 4 wooden stud walls, and a stucco exterior
finish. The peak of the roof is about 10 feet from the floor, and
the exterior walls are about 8 feet high. The interior volume of
barn 64 is approximately 13,500 cubic feet. The exterior doors are
not weather sealed and the total unsealed area around the exterior
doors 66, 68, 70, 72, and 74 combined is from approximately 1 to 2
square feet. No significant pressure differential exists between
the interior of barn 64 and the external environment, and any
moisture content differential between the interior of barn 64 and
the ambient environment tends rapidly towards equilibrium. Stall
partitions 82, 84, 86, and 88 are half height, and stall dividers
80 and 78 are full height extending to within approximately 6
inches of the roof. Interior gate 76 is a full height security
screen door.
[0054] The air conditioning system employed in barn 64 consists of
tube and shell heat exchanger 10, combined exhaust conduit 58, air
distribution chamber 92, air distribution branches 94 and 96, and
air outlet heads 98 and 100. Input fans 42 and 44 supply ambient
air from the interior of barn 64 to the shell plenum in heat
exchanger 10. The air is typically drawn into the shell side of the
heat exchanger from a level well below the level at which air is
discharged at 98 and 100. Air is preferably drawn into the tube
side of the heat exchanger from the hottest part of the structure
adjacent to the uninsulated roof. Air exhausted from the tube side
of heat exchanger 10 through tube side exhaust conduit 22 mixes
with air exhausted from the shell side through conduit 20, and
flows through combined exhaust conduit 58 to air distribution
chamber 92. The air stream then splits and flows through each of
air distribution branches 94 and 96 to respective air outlet heads
98 and 100. Air is drawn into the tube side of heat exchanger 10
through inlet port 12. Blanket material 104 (FIG. 6) in the form of
conventional swamp cooler foam pads is in contact with tubes 34. A
spray head of the general configuration shown in FIG. 3 positioned
in the top of the shell plenum of heat exchanger 10. Preferably,
approximately the lower one-quarter of the shell plenum is filled
with water.
[0055] The rectangular exterior case of heat exchanger 10 is
approximately 3 feet high by 2 feet by 2 feet, and it rests on the
floor of barn 64. Input fans 42 and 44, mounted on opposed sides of
the case, are 14 inches in diameter, run at 2,200 revolutions per
minute, and operate on 12 volts of direct current. The rated
amperage of these fans is 4 amps. The tube side exhaust fan 46
(FIG. 1) is a 12 inch, 12 volt, direct current, 4 amp fan. These
fans are conventional automotive equipment, and they are typically
used in association with conventional radiator cooling systems to
pull air through the radiator of a liquid cooled internal
combustion engine. The liquid pump 24 (FIG. 1) has a 12 volt, 7
amp, direct current motor, and a rated flow rate of 28 gallons per
hour. The dimensions of the tube side intake plenum 14 (FIG. 1) are
about 6 inches high by 24 inches by 24 inches. The dimensions of
the tube side exhaust plenum 18 (FIG. 1) are about 6 inches by 24
inches by 24 inches. The dimensions of the shell side plenum 16
(FIG. 1) are about 24 by 24 by 24 inches. The heat exchange tubes
34 are straight sections of standard three-quarter inch cylindrical
copper tubing having a length between tube sheets 32 and 60 of
about 24 inches. There are 100 heat exchange tubes 34 arrayed in a
generally regularly spaced rectangular pattern. The total surface
area of the tubes 34 within shell plenum 16 is approximately 6,600
square inches. The intake port 12 for the tube side of the heat
exchanger has a diameter of about 6 inches as do conduits 20 and
22. Intake port 12 opens upwardly and is positioned approximately 4
inches below the uninsulated metal roof of barn 64 so it is taking
in approximately the hottest air within the interior of barn 64.
Combined exhaust conduit 58 runs overhead, as do air distribution
branches 94 and 96. The diameter of conduit 58 is about 8 inches,
and conduit 58 is approximately 14 feet long. Each air distribution
branch is approximately 10 feet long and 6 inches in diameter. The
distribution box 92 is approximately 2 by 2 by 2 feet. The short
leg of conduit 58 that runs into distribution box 92 is
approximately 3 feet long. Air outlet heads 98 and 100 discharge
downwardly at a height of approximately 9 feet above the floor.
[0056] The pump and fans have, for example, direct current motors
powered by 5 conventional 12 volt deep cycle lead acid secondary
batteries connected in parallel, indicated generally at 106. The
batteries are connected through a conventional charging circuit
indicated generally 108 to 3 conventional 30 volt, 4 amp hour solar
panels indicated generally at 110, 112, and 114. The solar panels
are mounted on the south facing pitch of the roof of barn 64. No
other power source is required for the full time daylight operation
of the air conditioning system. If desired, a conventional AC
converter could be used to charge the batteries off of regular 110
volt house current, or some other power from a commercial utility
service. This is not necessary, and would add to the cost of
operation while limiting the system to use only at locations where
commercial utility service is available. Likewise, the motors on
the fans and pump could be replaced with conventional motors that
would operate on power from a commercial utility service, but the
costs of operation would be increased, and the flexibility of the
system would be compromised.
[0057] The level of water in the sump is preferably maintained at
approximately 5 inches. At this level the sump contains
approximately 1.67 cubic feet of water. The shell side plenum has a
volume of approximately 8 cubic feet, so the water occupies
approximately 21 percent of the volume of the shell side plenum 16.
This provides an adequate reserve of water to continue operations
for more than a day. Other sump volumes can be used if desired,
ranging from, for example, approximately 10 to 30 percent of the
volume of the shell side plenum chamber 16. The sump need not be
within the shell side plenum chamber. An external sump several
times larger than the shell side plenum can be used if desired so
as to provide for at least a week of unattended operation without
replenishing the water supply. Less than a gallon of water is
consumed during the course of the daylight hours in a typical
summer day.
[0058] Barn 64 is located in a desert area where the daytime
temperatures typically exceed 100 degrees Fahrenheit for several
months during the summer, the relative humidity is often below 20
percent, and the sun shines for most of the daylight hours. Without
air conditioning, the temperature at mid-day within barn 64 usually
exceeds the outside temperature by at least approximately 10
degrees Fahrenheit.
[0059] The operation of the air conditioning system in barn 64 can
be automated by providing a conventional thermostat (not shown)
connected to the fans and pump circuits. Setting a thermostat at,
for example, 74 degrees Fahrenheit, will activate the system early
in the morning on a typical summer day, and keep it running well
into the evening hours.
[0060] A preferred air conditioning assembly according to the
present invention is fully self contained. That is, the power
supply for the fan and pump motors is at the same location as the
rest of the system. The water supply on the shell side of the heat
exchanger can be replenished automatically by a float actuated
valve on a water line, or manually, as desired. Where no reliable
water supply is available, the rate of water consumption is so low
that manual replenishment at widely spaced intervals is
practical.
[0061] The power requirements are so small that a low voltage (12
or 24 volts) battery system coupled with a conventional solar panel
driven charging circuit is sufficient to power the system during
the daylight hours. The convenience of using a conventional solar
panel charged battery system, and the widespread availability of
such inexpensive systems, makes practical the unattended air
conditioning of a wide variety of structures. Even livestock barns,
for example, can be reliably and inexpensively air conditioned
according to the present invention. Dwellings occupied by humans
can likewise be air conditioned, even where very limited funds are
available to devote to this purpose, and the dwellings are poorly
sealed and uninsulated. The battery system can also be charged by
wind turbines in areas where reliable wind flows are available.
Other alternative energy sources can be used, if desired.
Combinations of solar panels, wind turbines and other forms of
alternative energy are suitable for use in charging the battery
system. Since alternative energy sources typically do not deliver a
constant level of energy, and the motors employed in the system
require a substantially constant energy source, batteries are
preferably interposed between the energy source and the air
conditioning system. Where an alternative energy source is capable
of delivering a constant source of energy, the use of a battery
system is optional.
[0062] The air conditioning system according to the present
invention was turned on in barn 64 at about 6:30 In the morning on
a typical sunny summer day, and allowed to run all day. The inside
temperature of barn 64 was measured at approximately location 102
(FIG. 5) approximately 4 feet above the ground, and the exterior
temperature was measured in the shade under an open awning adjacent
to the south side of barn 64 at approximately location 116.
Location 116 is at a height of about 5 feet above the ground on a
support for a 20 foot wide awning (not shown). The wooden awning is
attached to the barn and extends outward from the level of the top
of the wall of the barn 64 for about 20 feet. The wooden awning is
completely open on three sides, The temperature at 116 is
approximately what the temperature would be Inside of barn 64
without the air conditioning system. The temperatures observed were
as shown In Table 1 below.
1TABLE 1 Inside temperature Exterior temperature Time at 1.02. in
.degree. F. at 116, in .degree. F. 6:30 78 Not Recorded 7:30 72 Not
Recorded 8:30 71 Not recorded 9:30 72 98 10:30 72 99 11:30 73 105
12:30 75 104 1:30 75 100 2:30 77 98 3:30 76 98
[0063] It has been observed that the temperature difference between
the interior and exterior is the greatest when the humidity is the
lowest and the outside temperatures are above 100 degrees
Fahrenheit.
[0064] On a summer day when the sky was mostly overcast and the
relative humidity was above approximately 35 percent, the following
conditions were observed:
2TABLE 2 Outside temperature Interior temperature Time at 116, in
.degree. F. at 102, in .degree. F. 6:30 83 Not Recorded 9:30 85 75
10:30 90 74 11:30 90 82 12:30 92 80 1:30 92 80 2:30 90 79 3:30 91
76
[0065] Relative humidity measurements were taken at various
locations in and around barn 64 on a sunny summer day commencing
about 9:00 a.m.
[0066] The readings at the locations indicated by the listed
reference numbers in FIG. 5 were recorded in Table 3.
3TABLE 3 Measurement Locations As Shown On FIG. 5 Time 98 100 78
116 44 42 9:00 30% 30% 31% 19% 31% 31% 10:00 30% 30% 31% 18% 32%
32% 11:00 34% 34% 32% 18% 31% 30% 12:00 35% 34% 34% 19% 30% 30%
1:00 37% 36% 35% 18% 32% 32% 2:00 34% 34% 35% 17% 31% 31% 3:00 34%
34% 35% 16% 32% 32% 4:00 34% 34% 35% 16% 32% 32%
[0067] The relative humidity remains substantially stable and
constant throughout the day and throughout the interior of the
structure.
[0068] Commencing about 9:00 a.m., Temperature and relative
humidity measurements (T/H) were taken throughout a sunny day at
various locations within and adjacent to barn 64. The readings were
taken at the locations indicated by the reference numbers in FIG. 5
and were recorded in Table 4. The measurements at locations 118 and
120 were taken about 5 feet above the floor. Location 118 gives an
indication of the effect of radiation from the exterior wall.
Location 124 is on the north side of the barn 64 about 5 feet above
the ground. The measurements were as follows:
4TABLE 4 Measurement Locations As Shown On FIG. 5 116 120 98 100
Time T/H T/H T/H T/H 118 T 122 T 124 T 9:00 78/19 70/30 72.1/30
70.8/30 69.6 64.1 85.5 10:00 82/18 73/30 75.1/30 76.4/30 72.1 65
85.7 11:00 90/18 75/27 77.9/34 79.3/34 75.2 65.2 90.5 12:00 94/19
79.9/37 74.4/35 74.2/34 78.7 65.4 94.3 1:00 100/18 82.1/40 76.3/37
76.1/36 80.9 67.5 98.1 2:00 106/17 83.5/37 77.8/34 77.9/34 83.9
69.8 100.1 3:00 116/16 83.1/37 79.2/34 79.4/34 87 71.9 107 4:00
118/16 85.7/34 80.6/34 80.6/34 89.7 71.4 108 5:00 118/17 86/32
81.2/na 81.2/na 93 71.8 107.3 6:00 112/13 87/32 84.3/na 84.3/na
94.7 72.4 108
[0069] The temperature and relative humidity measurements as
reported in Table 4 were repeated under higher humidity conditions
commencing about 10 a.m. on a somewhat cloudy day. The system was
activated by a conventional thermostat set at about 74 degrees
Fahrenheit. The results are set forth in Table 5.
5TABLE 5 Measurement Locations As Shown On FIG. 5 Time 116 T/H 120
T/H 98 T/H 100 T/H 118 T 122 T 124 T Volts 10:00 86/33 78.5/44
73.6/31 73.6/31 69.2 81 12 11:00 92/27 79/49 75.7/32 75.7/32 74
68.4 88 11.6 12:00 92/23 79.5/47 76.7/31 77.1/31 75 69.3 89 11.4
1:00 95/23 80.1/47 77.4/31 77.5/31 79 71.2 97 11 2:00 97/20 80.2/45
79.6/33 79.9/32 79 74 98 9.4 3:00 98.3/20 83.0/ 81.6/34 81.7/34 80
73.8 98 9.7 30** 4:00 106/20 84.1/41 81.6/34 81.9/34 92 74.5 99 9.6
5:00 110/22 84.1/42 82.1/34 82.2/31 94 74.2 101 9.1 6:00 110/25
85/43 82.8/35 82.8/35 94 74.4 101 10.3* 7:00 102/33 85/47 81.2/35
81.7/35 91 74.2 100 10.0 8:00 96/42 83.1/47 80.1/35 79.2/35 90 73.6
96 11.1 9:00 84/42 80.1/47 76.3/36 77.1/36 89 72.5 81 12 10:00
77/44 78.1/47 74.1/34 74.7/34 87 71.1 77 12.5 11:00 75/44 76.1/47
74.0/34 74.1/34 83 69.4 74 12.5 12:00 75/44 73.1/46 73.4/32 73.4/32
79 67.1 74 12.5
[0070] A conventional 110 volt battery charger was connected to the
nominal 12 volt battery system at about 6 p.m. The effectiveness of
the solar battery charging system was diminished by occasional
cloud cover during the day. This relative humidity reading is
reported here as recorded, but, considered in light of the
contemporaneous readings at locations 116, 98, and 100, it is
believed to reflect an operator or instrument error, and is not
considered to be reliable. It is not reflected in relative humidity
curve 120-5 in FIG. 7.
[0071] The curves in FIG. 7 are based on the data recorded in
Tables 4 and 5 at locations 116 and 120 in FIG. 5. The relative
humidity and temperature curves 116-4 in FIG. 7, for example, were
drawn based on the data In the column headed "116 T/H" in Table 4,
and curves 116-5 were drawn based on the data in the column headed
"116 T/H" in Table 5. The last number following the dash indicates
which Table the information for the curve is taken from.
[0072] A comparison of the temperature differences between
temperature curves 120-5 and 116-5 at various relative humidity
readings, as shown by relative humidity curve 116-5, indicates that
the air conditioning system according to the first embodiment of
the present invention is most effective at exterior temperatures
above approximately 90 degrees Fahrenheit and relative humidity
readings below approximately 40, and preferably below approximately
35 percent. At exterior relative humidity conditions below
approximately 20 percent, temperature differences of as much as
approximately 35 degrees Fahrenheit were achieved. See, for
example, the differences between temperature curves 116-4 and 120-4
and relative humidity curve 116-4 in FIG. 7. While the temperature
in the open shade reached almost 120 degrees Fahrenheit, the
temperature in barn 64 did not reach over about 87 degrees
Fahrenheit. A temperature of 120 degrees is life threatening while
a temperature of 87 degrees is generally not. The efficiency of the
system is best when the relative humidity is below approximately 25
percent. See, for example, how temperature curves 120-5 and 116-5
quickly converge once the relative humidity exceeds approximately
35 percent, and actually cross at approximately 45 percent relative
humidity.
[0073] The last column in Table 5 reflects a drop in the voltage of
the battery system during the hours of peak demand. This voltage
drop is reflected in a decrease in the volume of air that the
various fans are able to move through the system. Although
Applicant does not wish to be bound by any theory, it appears that
there is a small temperature rise (temperature curve 120-5, FIG. 7)
that may be correlated with the reduced volume of air moving
through the system between approximately 2 p.m. and 6 p.m. The
system appears to be relatively insensitive to small changes in the
volume of air flowing through the system. Preferably, the voltage
should be at least approximately 11 volts for optimum operation of
the fan motors. Adding another one or two solar panels to the
existing three panel array on the roof of barn 64 would provide
enough capacity to hold this voltage during peak demand
periods.
[0074] The column headed "122 T" in Table 5 indicates the exterior
temperature of the shell side of the heat exchanger. The water
within the shell side is typically approximately 10 to 15 degrees
Fahrenheit cooler than location 122. This affords the opportunity
to provide some cooling to objects placed in heat exchange
relationship with this water. If access is provided to the shell
side, small objects can be cooled somewhat without the expenditure
of significant additional amounts of energy. The shelf life of
small amounts of heat sensitive food stuffs or medicines can be
extended by placing them in heat exchanging relationship with this
water. Suitable containers can be placed directly in the water on
the shell side, or a cabinet accessible from the outside can be
built into the shell side, or a stream of water circulated through,
for example, cooling coils external to the shell side, or the like,
can be utilized to effect the cooling of objects.
[0075] The column headed "118 T" in Table 5 gives a rough
indication of the heat that is being radiated into the interior of
the structure by the exterior walls. The column headed "124 T"
provides a rough indication of the effect of cooling the interior
of barn 64 on the temperature of the exterior of the walls.
Clearly, a significant amount of heat is being transferred through
the uninsulated walls of barn 64. Location 116 is far enough from
the adjacent wall that there is very little if any influence on the
indicated temperature by reason of the cooling of the interior of
the barn 64. Comparison of columns 120, 98, and 100 indicates that
the temperature is relatively uniform throughout the interior of
barn 64.
[0076] It has been found that thermally insulating the case that
encloses the heat exchanger improves the efficiency of the system
by as much as 10 percent or more. The temperature of the body of
water on the shell side tends to be reduced by the presence of the
thermal insulation. The degree of thermal insulation is preferably
such that the exterior temperature of the shell side of the heat
exchanger (Table 5, column 122T) is at least 3, and preferably 5
degrees Fahrenheit warmer than the equivalent uninsulated metal
exterior shell side temperature at an ambient air temperature of
approximately 80 degrees Fahrenheit. Changing from a metal case (18
gauge steel) to a fiberglass (glass filament reinforced
thermosetting resin) case with a thickness of approximately
one-eighth inch reduces the temperature by approximately 5 degrees
at about 80 degrees Fahrenheit ambient internal air temperature.
The efficiency of the air conditioning system also increases.
Numerous forms of insulation and methods of application are
suitable for this purpose, as will be understood by those skilled
in the art.
[0077] The rate of water consumption in an air conditioning, system
according to the present invention is very low. For example, in the
operation of the embodiment described herein with reference to FIG.
5 the rate of water consumption is no more than approximately 5
percent that of a conventional evaporative cooler (commonly
described as a swamp cooler) operating under the same conditions.
This low rate of water consumption is achieved even though the
structure or other confined space is uninsulated, and is so
unsealed that it is free to leak substantial volumes of air. In
general, the rate of water consumption of a heat exchanger
according to the present invention is less than approximately 10
percent, and preferably less than approximately 5 percent that of a
conventional direct evaporative cooler (in a conventional
evaporative cooler a single stream of air passes through a moist
environment and is cooled and humidified by the evaporation of
water) operating under substantially the same conditions external
to the cooling systems. For comparison's sake, substantially the
same external conditions comprise about the same exterior
conditions of temperature and relative humidity, and the same
structure or other confined space with, for example, the same
volume, shape, and insulation. For purposes of comparison, the
differences in the results from the operation of the cooling system
of this invention as compared to the operation of a conventional
evaporative cooler arises from the differences in the cooling
systems, and not from the environment external to the coolers or
the characteristics of the structure or other confined space. All
of the variables, other than those inherent in the two cooling
systems, are held constant for comparison purposes. That is, all of
the external variables are held substantially constant. This low
rate of water consumption is achieved while typically enjoying a
humidifying efficiency (dry-bulb temperature drop across the heat
exchanger divided by the maximum possible dry-bulb temperature drop
as determined from a Psychometric chart) of from approximately 30
to 40 percent.
[0078] The relative humidity within the interior of an air
conditioned structure according to the first embodiment of the
present invention is substantially below that which would be
expected from a conventional evaporative cooler. Comparison of, for
example, the data in columns "116 1/H" and "120 T/H" in Tables 4
and 5 reveals that when the exterior ambient temperature exceeds
approximately 95 degrees Fahrenheit, and the exterior ambient
relative humidity falls below approximately 25 percent, the
relative humidity within the structure is only approximately twice
(200 percent) that in the exterior environment. As the exterior
relative humidity falls below approximately 20 percent, and the
temperature exceeds approximately 100 degrees Fahrenheit, the
interior relative humidity is generally greater than approximately
twice that of the ambient exterior environment, but still less than
approximately 2.3 times (230 percent) that of the ambient exterior
environment. These low interior relative humidities of less than
approximately 50 percent are obtained while maintaining the
interior ambient temperatures below approximately 85 degrees
Fahrenheit despite exterior temperatures of approximately 110 to
120 degrees Fahrenheit. Typical interior relative humidities of
less than approximately 60 percent are achieved according to the
present invention whereas interior relative humidities in excess of
approximately 60 percent are typically found with conventional
evaporative coolers operated under the same conditions. This
minimizes the growth of mold, and the like, as well as increasing
the comfort of the occupants of the structure or other confined
space. At these low relative humidities, temperatures of less than
approximately 85 degrees Fahrenheit are generally comfortable for
most people. As will be recognized by those skilled in the art,
achieving these conditions with unsealed, uninsulated structures,
and with a very low rate of water consumption using only an ambient
energy harvesting system such as, for example, solar or wind
energy, as described above, provides a very economical air
conditioning system that is highly desirable and beneficial in many
ways and for many purposes.
[0079] Variable Humidity Embodiment of the Invention:
[0080] Referring now to FIGS. 8-18, a variable humidity embodiment
of the invention will be described which can be used in high
temperature, low humidity environments such as that previously
described, but which can also be used in higher humidity
environments, including tropical or semi-tropical environments.
[0081] With reference to FIG. 8, there is shown an air conditioner
201 which is a combined direct/indirect evaporative cooler with
refrigerated chilled sump water. The variable humidity device 201
shown in FIG. 8 has a number of common features with the low
humidity device described with reference to FIGS. 1-7. The air
conditioner 201 is preferably designed as a stacked arrangement
having a top section 203, a middle section 205 and a bottom section
207. A refrigeration compressor 209 and a storage battery 211 (FIG.
9) occupy the top section 203 of the design and rest on a top shelf
213. The top shelf 213 forms the top wall of an exhaust air plenum
215. A forced-air evaporative cooling chamber (217 in FIG. 9) is
located below the exhaust air plenum and occupies the middle
section of the design. The cooling chamber comprises a shell plenum
for the air conditioner and comprises about 65% of the total height
of the unit in the particular embodiment illustrated in the
drawings. A cold water sump 219 is located in the bottom of the
cooling chamber. The bottom floor 223 of the cooling chamber 217
also comprises the top wall of an intake plenum 221 housing an
intake fan 225. The intake fan 225 draws air upwardly through a
plurality of riser tubes 227 which connect the intake plenum 221
with the exhaust plenum 215 and which pass through the cooling
chamber 217.
[0082] As shown in FIGS. 10, 12 and 13, the bottom floor 223 of the
cooling chamber has a plurality of openings 224 which form a lower
tube sheet for the riser tubes 227. Similarly, the top shelf and
wall 213 have aligned openings (214 in FIG. 13) which form an upper
tube sheet. In the embodiment of the invention illustrated in FIGS.
8-15, there are approximately 49 copper tubes of approximate
1/4-{fraction (3/8)} inch diameter arranged vertically within the
cooling chamber 217 between the tube sheets. The sizing and
arrangement of the tube bundle creates a back pressure effect
during operation which acts as a self-regulating thermostat.
[0083] Water in the cold water sump 219 is refrigerated by the
refrigeration compressor 209 located in the top section of the
design. Cold water from the cold water sump 219 is introduced into
the evaporative cooling chamber through a distribution header 229.
The distribution header in FIG. 9 is a series of PVC pipes which
have downwardly directed perforations. The cold water which is
sprayed downwardly from the distribution header saturates an
evaporative media which surrounds or otherwise contacts the riser
tubes 227 in the cooling chamber 217. The evaporative media is
removed for ease of illustration in FIGS. 9 and 11 but can comprise
any of the media materials previously described with respect to the
first embodiment of the invention. Preferably, the evaporative
media is supplied as generally rectangular pads which are suspended
from a rack (241 in FIG. 14) on the roof of the cooing chamber so
that the pads are spaced between and separate the various vertical
riser tubes 227.
[0084] Air is introduced into the cooling chamber by means of
oppositely arranged fans 231, 233. The fans 231, 233 are mounted on
louvers (235, 237 in FIG. 11) which can be manually adjusted to
direct incoming and exhaust air from the cooling chamber 217 in a
circular, vortex type flow path which creates a turbulent air flow
in the cooling chamber 217 and which enhances the evaporative
cooling process. The vortex effect created by the side louvers 235,
237 causes air moving through the cooling chamber 217 to have an
increased residence time within the cooling chamber. This increases
the cooling effect and also prevents water droplets from being blow
directly out of the shell plenum. Cooled air from the cooling
chamber can be discharged through a suitable duct (such as duct 239
in FIG. 8) to the interior of the structure to be cooled or can be
discharged to the atmosphere.
[0085] Air is also being drawn into the intake plenum 221 by the
intake fan 225, which air flow is forced upwardly through the riser
tubes 227 located in the cooling chamber. The riser tubes pass
though the cold water sump and also contact the evaporative media
in the cooling chamber, so that the outside of the tubes are
cooled. The air within the tubes 227 is cooled by conduction
through the tubes. This relatively drier air can be directed
through a suitable duct to the interior of the structure to be
cooled and can be combined with the cooled air from the cooling
chamber, if desired.
[0086] In this latter embodiment of the invention, air is being
cooled using two simultaneous processes. Air is cooled by direct
contact with water in the evaporative cooling chamber 217, raising
the absolute humidity of the air cooled in this manner. Additional
air is also being cooled by conductive heat transfer within the
riser tubes 227. The absolute humidity of this additional air is
either unchanged or only slightly changed, or decreases slightly,
due to condensation on the inside of the riser tubes. If desired,
the two air flows can be combined into a single discharge duct as
described with respect to the first embodiment of the invention, so
that the discharged air consists of a mixture of relatively humid
air from the evaporative process and air with near ambient
humidity. Control over the humidity of the discharged air can
therefore be obtained by simply regulating the ratio of the two
previously described air flows passing thru the exhaust duct.
[0087] The cold water sump (illustrated generally at 219 in FIG. 9)
at the bottom of the cooling chamber serves as a cooling mass, as
well as a sump. The water in the sump is refrigerated to near
freezing by means of a commercially available, low temperature
compressor similar to that used on an ice machine and which can be
AC or DC operated, but is preferably operable on 12 Volt DC power.
In the embodiment of the invention illustrated in FIG. 11, the
compressor 209 is battery operated. However, an associated inverter
243, located within the exhaust plenum area 251 allows the unit to
be operated off AC current to, for example, charge the batteries,
during non-peak hours of operation. Locating the inverter within
the chilled exhaust plenum compartment prolongs its life since the
operating temperature is reduced. The electric fans used in the
intake plenum and on the cooling chamber are also preferably 12
Volt DC fans which can be driven by solar cells or storage
batteries. FIGS. 10, 11 and 16, 16A and 16B illustrate a
particularly preferred refrigeration manifold 245 which is cooled
by the compressor 209 using traditional mechanical refrigeration
techniques. While a number of different traditional manifold or
coil arrangements could be utilized with the compressor 209 to cool
the water in the sump 219, the preferred manifold 245 is especially
efficient for the intended application. As best seen in the
isolated view of FIG. 16, the manifold 245 is a double stock
manifold having a front layer 247 and a rear layer 249. The front
and rear layers or coils are spaced apart by means of a plurality
of cylindrical spacers 251. The cylindrical spacers 251 are less
wide than the total width of the manifold, leaving a distance "d"
between adjacent spacers. The cylindrical spacers are also hollow
and open at both ends, allowing water in the sump 219 to flow
around and through the spacers. As shown in FIG. 11, the manifold
245 is arranged in a generally horizontal plane when in place in
the sump region of the cooling chamber.
[0088] Refrigerant is supplied to and returned from the manifold
layers by a pair of "splits", shown generally at 253 and 255 in
FIG. 16. As shown in FIG. 16B, the top layer of coils is made up of
loops 252, 254, 256, 258, 260, 262, 264, and 266. (The loops are
shown as broken-away halves for ease of illustration.) The rear
layer of loops is made up of loops 268, 270, 272, 274, 276, 278,
280 and 282. The loop halves 252-266 form a continuous coil on the
front of the manifold. The loop halve 268-282 similarly from a
continuous loop on the rear of the manifold. The points at which
the front and rear loops exit or terminate (generally 266,268 in
FIG. 16B) are connected by cross-over pipes 284, 286. The
cross-over pipes 284, 286 intersect the first loop halves (252,
282, in FIG. 16B) to form the "splits 253, 255. The cross-over
piping arrangement and the splits 253 and 255 result in a type of
"interlayered flow" through the manifold. For example, refrigerant
passing through the split 253 flows through branch 253B (FIG. 16)
to the front layer 247 and through branch 253A to the rear layer
249. Refrigerant returning from the front and rear layers 247, 249
meets at the split 255. The double stock manifold with its split
flow operation nearly doubles the cooling capacity of the
compressor 209.
[0089] The following description is taken from an actual test run
of the device illustrated in FIGS. 8-15, as described above.
Without intending to be limiting, the following test results are
intended to illustrate the features of a particularly preferred
embodiment of the invention. The case or housing sections of the
device were formed of stainless steel. Two 12 volt fans, installed
on opposite sides of the unit were used to draw outdoor atmospheric
air into the main wet chamber, referred to herein as the "wet side"
of the unit. Copper tubes extended through the wet chamber and a
single 12 volt fan was used to force air through the tubes on what
will be referred to as the "dry side" of the unit. The air supply
to the dry side came through a duct that extended into the
conditioned space. The two airstreams (dry and wet side) were
combined inside the unit and directed to a single outlet. The unit
incorporated an integral mechanical refrigeration unit used to
chill the water in the sump of the wet chamber. Batteries for 12
volt DC operation of the unit and an invertor were present to allow
the operation of the unit from 120 volt AC and for charging of the
batteries.
[0090] Description of the Test Unit Installation:
[0091] The test unit was set up outside an enclosed automotive
repair garage in Banning Calif. The air supply for the secondary
(wet) side of the unit was taken from the outdoor atmosphere. The
garage was approximately 30' by 35' with an approximate 14' high
ceiling. The combined outlet airstream and the supply air to the
primary (dry) sides of the unit were ducted through a door into the
enclosed garage space. Both ducts were approximately 10' long and
straight with no turns. The duct for the combined air outlet of the
unit was 10.25" I.D. (inside diameter) and the duct for the primary
(dry) side was 7.0" I.D.
[0092] One door to the garage was left open to air for air to
escape the garage and to eliminate any back pressure buildup in the
garage space. For the first two tests, the unit was positioned only
inches from the door. For the third test, the unit was moved back
approximately 10' from the door but the two ducts still extended
through the door into the enclosed space. For all three tests, the
unit was located in the shade.
[0093] Test Data and Results
6 Test # 1 For this test the unit was not plugged into AC power and
ran off battery power. Outdoor ambient [also secondary(wet) inlet]
79.8.degree. F., 19% RH, 480 cfm (Ft.sup.3/Min) Primary (dry) inlet
condition 68.7.degree. F., 28% RH, 10 cfm Combined air outlet
63.3.degree. F., 42% RH, 490 cfm Air flow volume proportion 2%
primary (dry) and 98% secondary (wet) Dry-bulb temperature drop
across the unit. 16.3.degree. F. (79.6 - 63.3) (used weighted
average of primary and secondary air inlet streams) Theoretical
maximum dry-bulb from 23.5.degree. F. (79.6 - 56.1) psychrometric
chart. Calculated humidifying efficiency. 69% (16.3 .div. 23.5
.times. 100) Sump water temperature 43.degree. F. Test #2. For this
test, the unit was plugged into AC power and was run off of the
invertor. Outdoor ambient [also secondary (wet) inlet] 79.7.degree.
F., 17% RH, 532 cfm (Ft.sup.3/Min) Primary (dry) inlet condition
68.0 F, 30% RH, 10 cfm Combined air outlet 63.3.degree. F., 31% RH,
542 cfm Air flow volume proportion 2% primary (dry) and 98%
secondary (wet) Dry-bulb temperature drop across the unit.
15.9.degree. F. (79.5 - 63.6) (used weighted average of primary and
secondary air inlet streams) Theoretical maximum dry-bulb from
24.1.degree. F. (79.5 - 55.4) psychrometric chart. Calculated
humidifying efficiency. 66% (15.9 .div. 24.1 .times. 100) Sump
water temperature 45.degree. F. Test # 3. Same as test #2 except
the unit was moved 10' from door as described above. Outdoor
ambient [also secondary (wet) inlet] 79.5.degree. F., 18% RH, 532
cfm (Ft.sup.3/Min) Primary (dry) inlet condition 68.0.degree. F.,
30% RH, 10 cfm Combined air outlet 66.0.degree. F., 32% RH, 542 cfm
Air flow volume proportion 2% primary (dry) and 98% secondary (wet)
Dry-bulb temperature drop across the unit. 13.3.degree. F. (79.3 -
66.0) (used weighted average of primary and secondary air inlet
streams) Theoretical maximum dry-bulb from 23.8.degree. F. (79.5 -
55.4) psychrometric chart. Calculated humidifying efficiency. 56%
(13.3 .div. 23.8 .times. 100) Sump water temperature 46.degree. F.
Note: For all three tests the Calculating humidifying efficiency is
based on the cfm weighted average dry bulb temperature and relative
humidity % of the primary and secondary air inlet streams and the
combined output conditions.
[0094] As briefly mentioned above, the water within sump region 219
of the cooling chamber of the device is typically approximately 10
to 15 degrees Fahrenheit cooler than the surrounding environment.
This provides the opportunity to provide some cooling to objects
placed in heat exchange relationship with this water. For example,
small objects can be cooled without the expenditure of significant
additional amounts of energy. Suitable containers can be placed
directly in the water on the shell side, or a cabinet accessible
from the outside can be built into the shell side, or a stream of
water circulated through, for example, cooling coils external to
the shell side, or the like. As illustrated in FIG. 14, the water
sump region of the cooling chamber can be provided with one or more
pairs of auxiliary refrigeration jacks 257, 259 which can be
plugged or capped if not in use. The auxiliary jacks comprise an
inlet and outlet point for chilled water in the sump region of the
device. The chilled water can easily be pumped to another device in
the structure to be cooled, such as another heat exchanger, to
provide increased cooling.
[0095] FIG. 17 shows one such auxiliary refrigeration device 261.
The particular device illustrated is approximately 15" wide and 24"
high so that it can conveniently be located between the studs of a
wall in a residential dwelling. Water from the sump 219 of the air
conditioner 201 is sucked through conduit 263 to the intake of a
fluid pump 265. Pump 265 discharges chilled water through conduit
267 to coil 269. A 12 volt DC fan 271 located behind a 12 by 12
inch coil forces air over the coil and is used to discharge cool
air from the unit into the structure to be cooled. The fan can be
identical to the cooling chamber fans 231 and 233 used on the main
air conditioner unit. Return water is pulled through conduit 273
back to the pump 265 and recirculated by the pump back to the sump
219 of the main unit through the outlet conduit 275 to be once
again chilled by the mechanical refrigeration system of the main
unit. A catch pan 274 can also be provided to catch any
condensation. In one embodiment of the invention, the inlet and
outlet water conduits 263, 275 are packaged into a "cable"
arrangement (FIG. 18) having an outer sheath of, for example a
suitable polyolefin. The cable 277 could also contain a suitable
shielded DC power supply line, illustrated as 279 in FIG. 18, for
powering the fan 271 and pump 265.
[0096] Those skilled in the relevant arts will understand that
various changes and modifications may be made in the preferred
embodiments of the invention described above. Typical cooling
systems according to the present invention employ a heat exchanger
with wet and dry sides that are preferably substantially
hermetically sealed from one another. The water supply system on
the wet side of the heat exchanger is generally provided primarily
to humidify the air on the wet side. As is well understood by those
skilled in the art with respect to conventional evaporative
coolers, the liquid water on the wet side is divided or distributed
by means of a spray or a wetted pad, or the like, so as to increase
the surface area of the water, and, thus, the rate of evaporation
of the water. Some chilling of the water on the wet side also
necessarily occurs.
[0097] While the present invention has been described with
reference to specific embodiments wherein the shell side of a heat
exchanger is the wet side and the tube side is the dry side, those
skilled in the art will readily appreciate from a consideration of
these teachings that other arrangements are possible, including,
for example, the use of a wet tube side and a dry shell side, or
the like. Also, those skilled in the art will be taught by the
teachings herein that other forms of heat exchangers other than
shell and tube can be employed, if desired.
[0098] What have been described are preferred embodiments in which
modifications and changes may be made without departing from the
spirit and scope of the accompanying claims. Many modifications and
variations of the present invention are possible in light of the
above teachings. It is therefore to be understood that, within the
scope of the appended claims, the invention may be practiced
otherwise than as specifically described.
* * * * *