U.S. patent application number 11/801545 was filed with the patent office on 2008-11-13 for evaporative cooler and desiccant assisted vapor compression ac system.
Invention is credited to Mohinder Singh Bhatti, Shrikant Mukund Joshi, Ilya Reyzin.
Application Number | 20080276640 11/801545 |
Document ID | / |
Family ID | 39968299 |
Filed Date | 2008-11-13 |
United States Patent
Application |
20080276640 |
Kind Code |
A1 |
Bhatti; Mohinder Singh ; et
al. |
November 13, 2008 |
Evaporative cooler and desiccant assisted vapor compression AC
system
Abstract
An air conditioning system includes an evaporator assembly and a
condenser assembly. A first portion of the exhaust airstream leaves
the condenser and enters a primary channel of an evaporative cooler
assembly. Water evaporates from the evaporative cooler tubes and
creates a moisture-laden airstream. A plurality of apertures in the
evaporative cooler tubes bleeds the moisture-laden airstream into a
secondary channel defined within the evaporative cooler tubes. The
heat drawn from the air in the primary channel produces an
evaporatively cooled airstream that enters a desiccant wheel. A
solid desiccant material within the desiccant wheel absorbs
moisture from the evaporatively cooled airstream to produce a
dehumidified airstream that enters the evaporator assembly. A
second portion of the exhaust airstream is directed through a
heater and then into the desiccant wheel to provide heat for
regeneration of the solid desiccant material.
Inventors: |
Bhatti; Mohinder Singh;
(Amherst, NY) ; Reyzin; Ilya; (Williamsville,
NY) ; Joshi; Shrikant Mukund; (Williamsville,
NY) |
Correspondence
Address: |
DELPHI TECHNOLOGIES, INC.
M/C 480-410-202, PO BOX 5052
TROY
MI
48007
US
|
Family ID: |
39968299 |
Appl. No.: |
11/801545 |
Filed: |
May 10, 2007 |
Current U.S.
Class: |
62/271 |
Current CPC
Class: |
F24F 2203/1056 20130101;
F24F 3/153 20130101; F24F 2203/1068 20130101; F24F 2203/1016
20130101; F24F 2203/1084 20130101; F24F 6/00 20130101; F24F
2203/1032 20130101; F24F 3/1423 20130101 |
Class at
Publication: |
62/271 |
International
Class: |
F24F 3/14 20060101
F24F003/14 |
Claims
1. An air conditioning system comprising; an evaporator assembly
including a plurality of evaporator tubes for carrying a
refrigerant and an evaporator fan for moving a dehumidified
airstream across said evaporator tubes for transferring heat from
the dehumidified airstream to the refrigerant to evaporate the
refrigerant and to produce a conditioned airstream, a condenser
assembly including a plurality of condenser tubes in fluid
communication with said evaporator tubes and a condenser fan for
moving ambient air over said condenser tubes for transferring heat
from the refrigerant to the ambient air to condense the refrigerant
and to produce an exhaust airstream, an evaporative cooler assembly
defining a primary channel for receiving an incoming airstream and
for producing an evaporatively cooled airstream, and a desiccant
wheel including a solid desiccant material and a housing supporting
said solid desiccant material and a first air inlet in airflow
communication with said evaporative cooler assembly for receiving
the evaporatively cooled airstream and for directing the
evaporatively cooled airstream through a first sector of said
housing to cause an exothermic reaction with said solid desiccant
material to dry the evaporatively cooled airstream to produce the
dehumidified airstream and including a first outlet in airflow
communication with said evaporator assembly for directing the
dehumidified airstream over said evaporator tubes.
2. A system as set forth in claim 1 wherein said condenser tubes
are spaced apart from oneanother defining a condenser air passage
therebetween for receiving the ambient air and for discharging the
exhaust airstream and said evaporative cooler assembly is in
airflow communication with said condenser air passage for receiving
at least a first portion of the exhaust airstream and for cooling
the first portion of the exhaust airstream to produce the
evaporatively cooled airstream.
3. A system as set forth in claim 2 including a first conduit
connecting said condenser air passage to said evaporative cooler
assembly in airflow communication for directing at least the first
portion of the exhaust airstream to the primary channel of the
evaporative cooler.
4. A system as set forth in claim 3 wherein said evaporative cooler
assembly includes; a plurality of evaporative cooler tubes
extending vertically defining a secondary channel therein and
spaced apart from one another defining said primary channel
extending perpendicularly therebetween for receiving the first
fraction of the exhaust airstream, a water tank disposed about an
end of said evaporative cooler tubes and said evaporative cooler
tubes extending upwardly from said water tank and including a
wicking coating extending thereon for wicking water by capillary
action from said water tank into contact with said primary channel
for evaporation into a moisture-laden airstream to draw the latent
heat of vaporization from the first fraction of the exhaust
airstream to produce the evaporatively cooled airstream carried by
said primary channel, and a plurality of apertures disposed along
said evaporative cooler tubes for bleeding the moisture-laden
airstream from said primary channel into said secondary channel for
discharge from said evaporative cooler.
5. A system as set forth in claim 4 wherein said evaporative cooler
assembly includes a plurality of fins extending back and forth
between said tubes extending parallel with said primary
channel.
6. A system as set forth in claim 2 including a second conduit in
airflow communication with said condenser air passage and said
desiccant wheel including a second air inlet connected with said
second conduit for airflow communication with said condenser air
passage for directing at least a second portion of the exhaust
airstream through a second sector of said housing to cause an
endothermic reaction with said solid desiccant material to dry said
solid desiccant material and said desiccant wheel including a
second air outlet for discharging the second fraction of the
exhaust airstream.
7. A system as set forth in claim 6 including a heater disposed
along said second conduit between said condenser air passage and
said second air inlet for heating the second portion of the exhaust
airstream.
8. A system as set forth in claim 6 wherein said housing of said
desiccant wheel includes a pair of end plates spaced apart and a
plurality of desiccant tubes extending therebetween supporting said
solid desiccant material therewithin and a pair of trunnions each
extending from one of said end plates defining an axis and
supporting said desiccant wheel for rotation about said axis to
alternately move said solid desiccant material between said first
and second sectors to successively expose said solid desiccant
material to the second portion of the exhaust airstream and to the
evaporatively cooled airstream.
9. An air conditioning system comprising; an evaporator assembly
including a plurality of evaporator tubes for carrying a
refrigerant therein and said evaporator tubes being spaced apart
from oneanother defining a evaporator air passage therebetween for
receiving a dehumidified airstream to flow over said evaporator
tubes for transferring heat from the dehumidified airstream to the
refrigerant to evaporate the refrigerant within said evaporator
tubes and to produce a conditioned airstream within said evaporator
air passage, a condenser assembly including a plurality of
condenser tubes in fluid communication with said evaporator tubes
and spaced apart from oneanother defining a condenser air passage
therebetween and a condenser fan for moving ambient air through
said condenser air passage over said condenser tubes for
transferring heat from the refrigerant to the ambient air to
condense the refrigerant within said condenser tubes and to produce
an exhaust airstream within said condenser air passage, an
evaporative cooler assembly including a plurality of evaporative
cooler tubes extending vertically defining a secondary channel
therein and spaced apart from one another defining a primary
channel therebetween for receiving a first portion of the exhaust
airstream and for producing an evaporatively cooled airstream and a
moisture-laden airstream and said evaporative cooler tubes
including a plurality of apertures for bleeding the moisture-laden
airstream from said primary channel into said secondary channel, a
first conduit in airflow communication with said condenser air
passage and said, primary channel of said evaporative cooler for
directing the first portion of the exhaust airstream to said
primary channel, a desiccant wheel including a solid desiccant
material and a housing supporting said solid desiccant material and
a first air inlet in airflow communication with said primary
channel of said evaporative cooler assembly for receiving the
evaporatively cooled airstream and for directing the evaporatively
cooled airstream through a first sector of said housing to cause an
exothermic reaction with said solid desiccant material to dry the
evaporatively cooled airstream to produce the dehumidified
airstream and including a first outlet in airflow communication
with said evaporator assembly for directing the dehumidified
airstream over said evaporator tubes, said desiccant wheel
including a second air inlet for receiving a second portion of the
exhaust airstream and for directing the second portion of the
exhaust airstream through a second sector of said housing to cause
an endothermic reaction with said solid desiccant material to dry
said solid desiccant material and said desiccant wheel including a
second air outlet for discharging the second fraction of the
exhaust airstream, a second conduit in airflow communication with
said condenser air passage and said second air inlet for directing
the second portion of the exhaust airstream to said second sector
of said housing, and an exhaust flow divider connected in airflow
communication between said condenser air passage and said first and
second conduits for dividing the exhaust airstream into the first
and second portions.
10. An air conditioning system as set forth in claim 9 including a
heater disposed along said second conduit in airflow communication
between said condenser air passage and said second air inlet for
heating the second portion of the exhaust airstream.
11. An air conditioning system as set forth in claim 9 including a
water tank disposed about an end of said evaporative cooler tubes
and said evaporative cooler tubes including a wicking coating
extending thereon for wicking water by capillary action from said
water tank into contact with said primary channel for evaporation
into the moisture-laden airstream to draw the latent heat of
vaporization from the first fraction of the exhaust airstream to
produce the evaporatively cooled airstream carried by said primary
channel.
12. An air conditioning system as set forth in claim 9 wherein said
housing of said desiccant wheel is rotatably supported about an
axis for rotation about said axis to alternately move said solid
desiccant material between said first and second sectors to
successively expose said solid desiccant material to the second
portion of the exhaust airstream and to the evaporatively cooled
airstream.
13. A system as set forth in claim 9 including an evaporator fan
for moving the dehumidified airstream through said evaporator air
passage over said evpaorator tubes.
14. An air conditioning system comprising; an evaporator assembly
including a plurality of evaporator tubes for carrying a
refrigerant and an evaporator fan for moving a dehumidified
airstream across said evaporator tubes for transferring heat from
the dehumidified airstream to the refrigerant to evaporate the
refrigerant and to produce a conditioned airstream, a compressor in
fluid communication with said evaporator tubes for compressing the
evaporated refrigerant to produce a superheated vapor, a condenser
assembly including a plurality of condenser tubes in fluid
communication with said compressor and spaced apart from oneanother
defining a condenser air passage therebetween and a condenser fan
for moving ambient air through said condenser air passage over said
condenser tubes for transferring heat from the superheated vapor to
the ambient air to condense the superheated vapor into a liquid
refrigerant and to produce an exhaust airstream, an expansion
device in fluid communication with said condenser tubes and with
said evaporator tubes for decreasing the pressure on the liquid to
produce a sub-cooled liquid refrigerant for supply back to said
evaporator tubes, an evaporative cooler assembly including a
plurality of evaporative cooler tubes extending vertically and
spaced apart from one another and including a plurality of fins
extending back and forth between said evaporative cooler tubes
defining a primary channel extending perpendicularly between said
evaporative cooler tubes and being in airflow communication with
said condenser air passage for receiving a first portion of the
exhaust airstream for producing an evaporatively cooled airstream,
said evaporative cooler tubes including a plurality of internal
dividers extending within said tubes defining a secondary channel
extending perpendicularly to said primary channel, said evaporative
cooler assembly including a water tank disposed about an end of
said evaporative cooler tubes, said evaporative cooler tubes
extending upwardly from said water tank and including a wicking
coating extending thereon for wicking water by capillary action
from said water tank into contact with said primary channel for
evaporation into a moisture-laden airstream to draw the latent heat
of vaporization from the first fraction of the exhaust airstream to
produce the evaporatively cooled airstream carried by said primary
channel, said evaporative cooler tubes including a plurality of
apertures for bleeding the moisture-laden airstream from said
primary channel into said secondary channel for discharge from said
evaporative cooler, a desiccant wheel including a housing having a
pair of end plates spaced apart and a plurality of desiccant tubes
extending therebetween and a pair of trunnions each extending from
one of said end plates defining an axis, said desiccant wheel
including a solid desiccant material extending within each of said
desiccant tubes, said desiccant wheel including a first air inlet
in airflow communication with said primary channel of said
evaporative cooler for receiving the evaporatively cooled airstream
and for directing the evaporatively cooled airstream through a
first sector of said desiccant tubes to cause an exothermic
reaction with said solid desiccant material to dry the
evaporatively cooled airstream to produce the dehumidified
airstream and including a first air outlet in airflow communication
with said evaporator assembly for directing the dehumidified
airstream over said evaporator tubes, said desiccant wheel
including a second air inlet in airflow communication with said
condenser air passage for receiving a second portion of the exhaust
airstream and for directing the second portion of the exhaust
airstream through a second sector of said desiccant tubes to cause
an endothermic reaction with said solid desiccant material to dry
said solid desiccant material and including a second air outlet for
discharging second portion of the exhaust airstream, said desiccant
wheel being supported by said trunnions for rotation about said
axis to alternately move said solid desiccant material between said
first and second sectors to successively expose said solid
desiccant material to said desiccant regenerating airstream and to
said ambient air, a first conduit in airflow communication with
said condenser air passage and said primary channel of said
evaporative cooler for directing the first portion of the exhaust
airstream to said primary channel, a second conduit in airflow
communication with said condenser air passage and second air inlet
for directing the second portion of the exhaust airstream to said
second sector of said desiccant tubes, an exhaust flow divider
connected in airflow communication between said condenser air
passage and said first and second conduits for dividing the exhaust
airstream into the first portion and the second portion, and a
heater in airflow communication between said exhaust flow divider
and said second air inlet of said desiccant wheel for receiving the
second portion of the exhaust airstream and for adding heat to the
second portion of the exhaust airstream.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The subject invention relates generally to an air
conditioning system.
[0003] 2. Description of the Prior Art
[0004] Known air conditioning systems include an evaporator
assembly and a condenser assembly cooperating to cyclically
evaporate and condense a refrigerant. The evaporator assembly
includes a plurality of evaporator tubes carrying a refrigerant and
an evaporator fan for moving ambient air across the evaporator
tubes. Heat transfers from the air to the refrigerant, thereby
evaporating the refrigerant and producing a conditioned airstream.
The condenser assembly includes a plurality of condenser tubes in
fluid communication with the evaporator tubes. A condenser fan
moves ambient air over the condenser tubes, and heat transfers from
the refrigerant to the ambient air, thereby condensing the
refrigerant and producing an exhaust airstream. The exhaust
airstream is typically rejected to the atmosphere. The system also
includes a compressor for compressing the refrigerant into a
superheated vapor prior to entering the condenser, and an expansion
device for reducing pressure on the refrigerant to produce a
sub-cooled liquid prior to entering the evaporator.
[0005] This system requires a significant amount of energy input.
The greater the difference between the ambient air and the desired
temperature of the conditioned air, the faster the refrigerant must
cycle through the system, in order to continue exchanging the heat.
Much of the energy required is used in the compressor. Efforts have
been made to reduce the load on this system. The two types of
cooling load on an air conditioning system are the sensible load,
and the latent load. The sensible load is the energy required to
reduce the dry bulb temperature of the conditioned air. Sensible
load is so named because the temperature difference can be sensed,
or detected, by an observer (e.g. a thermometer, or a person
occupying the cooled space). The latent load is the energy required
to condense water vapor in the ambient air onto the evaporator
surface. As the water vapor condenses on the cold evaporator
surface, it releases thermal energy, which is absorbed by the
refrigerant inside the evaporator tubes.
[0006] U.S. Pat. No. 6,776,001 to Maisotsenko, et al., teaches
reducing the latent load by using a desiccant wheel. However, the
reaction that occurs in a desiccant wheel gives off heat, so that
in many cases the desiccant wheel simply trades latent load for
sensible load. U.S. patent application Ser. No. 11/453,721,
assigned to the assignee of the present invention, teaches using an
evaporative cooler to reduce the sensible load of the air entering
the evaporator. However, this does nothing to reduce the latent
load of the incoming air, as the evaporative cooler does not reduce
humidity of the ambient air.
SUMMARY OF THE INVENTION AND ADVANTAGES
[0007] The invention provides for an air conditioning system
including an evaporator assembly. The evaporator assembly include a
plurality of evaporator tubes for carrying a refrigerant, and a
condenser assembly including a plurality of condenser tubes in
fluid communication with the evaporator tubes. A condenser fan
moves ambient air over the condenser tubes, and heat transfers from
the refrigerant to the ambient air to condense the refrigerant and
to produce an exhaust airstream. An evaporative cooler assembly
defines a primary channel for receiving an incoming airstream and
for producing an evaporatively cooled airstream. A desiccant wheel
has a solid desiccant material and a housing supporting the solid
desiccant material. A first air inlet is in airflow communication
with the evaporative cooler assembly for receiving the
evaporatively cooled airstream and for directing the evaporatively
cooled airstream through a first sector of the housing. An
exothermic reaction between the solid desiccant material and the
evaporatively cooled airstream occurs to dry the evaporatively
cooled airstream to produce a dehumidified airstream. A first
outlet is in airflow communication with the evaporator assembly for
directing the dehumidified airstream over the evaporator tubes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Other advantages of the present invention will be readily
appreciated, as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawings wherein:
[0009] FIG. 1 is a schematic of an air conditioning system
according to an exemplary embodiment of the present invention;
[0010] FIG. 2 is a perspective view of a desiccant wheel according
to the exemplary embodiment of the present invention;
[0011] FIG. 3 is a perspective view of an evaporative cooler
according to the exemplary embodiment of the present invention;
and
[0012] FIG. 4 is a psychrometric chart demonstrating the state of
the air as it cycles through the air conditioning system according
to the exemplary embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Referring to the Figures, wherein like numerals indicate
corresponding parts throughout the several views, an air
conditioning system is generally shown at 20. Referring first to
FIG. 1, the system 20 includes an evaporator assembly 22 having a
plurality of evaporator tubes 24 spaced apart from one another. An
evaporator air passage is defined between the evaporator tubes 24
to receive a dehumidified airstream flowing over the evaporator
tubes 24. The source of the dehumidified airstream will be
explained in more detail below. The evaporator tubes 24 carry a
sub-cooled liquid refrigerant, and an evaporator fan 26 is used to
move the dehumidified airstream across the evaporator tubes 24.
Heat transfers from the air to the refrigerant and evaporates the
liquid refrigerant into a vapor. The air is cooled to produce a
conditioned airstream and can then be directed as desired.
[0014] The evaporated refrigerant leaves the evaporator tubes 24
and heads into a compressor 28, which compresses the evaporated
refrigerant to produce a superheated vapor. A condenser assembly 30
includes a plurality of condenser tubes 32 spaced apart from one
another and in fluid communication with the compressor 28 to
receive the superheated vapor. A condenser air passage is defined
between the condenser tubes 32. A condenser fan 33 moves ambient
air through the condenser air passage over the condenser tubes 32.
Heat is transferred from the superheated vapor to the ambient air,
to condense the refrigerant into a liquid. The ambient air is
heated to produce an exhaust airstream leaving the condenser air
passage.
[0015] To complete the refrigeration cycle, an expansion device 34
is in fluid communication between the condenser tubes 32 and the
evaporator tubes 24. The expansion device 34 decreases the pressure
on the liquid to produce a sub-cooled liquid refrigerant for supply
back to the evaporator tubes 24.
[0016] Referring to FIG. 3, an evaporative cooler assembly 36 is
provided. The evaporative cooler assembly 36 includes a plurality
of evaporative cooler tubes 38 extending vertically and spaced
apart from one another. A plurality of fins 40 extends back and
forth between the evaporative cooler tubes 38 to define a primary
channel extending along the fins 40 and perpendicularly to the
evaporative cooler tubes 38. A plurality of internal dividers 42
extends within the evaporative cooler tubes 38 to define a
secondary channel extending perpendicularly to the primary channel.
A water tank 44 is disposed about an end of the evaporative cooler
tubes 38, and a wicking coating 46 extends along the evaporative
cooler tubes 38 for wicking water by capillary action from the
water tank 44 into contact with the secondary channel.
[0017] Referring to FIGS. 1 and 3, a first conduit 48 connects the
condenser air passage in airflow communication with the primary
channel of the evaporative cooler assembly 36. A first portion of
the exhaust airstream flows through the first conduit 48 to the
primary channel. A plurality of apertures 50 are disposed along the
evaporative cooler tubes 38 for splitting the airstream between the
primary and secondary channels. Therefore, a fraction of the first
portion of the exhaust airstream enters the apertures 50 and flows
into the secondary channel and flows over the wet surfaces. The air
in the secondary channel evaporates the water along the sides of
the evaporative cooler tubes 38 to produce a moisture-laden
airstream. The evaporation draws the latent heat of vaporization
away from the first portion of the exhaust airstream to produce an
evaporatively cooled airstream flowing through the primary channel
and having a lower dry bulb temperature than the ambient air. This
cooler airstream lowers the sensible load on the evaporator
assembly 22, thereby reducing the cooling load exerted by the
system 20. The moisture-laden airstream flowing through the
secondary channel can simply exit the evaporative cooler assembly
36 through the openings of the evaporative cooler tubes 38.
[0018] Referring to FIGS. 1 and 2, a desiccant wheel 52 is
provided. The desiccant wheel 52 includes a housing 54 having a
pair of end plates 56 spaced apart from one another. A plurality of
desiccant tubes 58 extend between the end plates 56, and a pair of
trunnions 60 each extend from one of the end plates 56 to define an
axis Z. A solid desiccant material extends within each of the
desiccant tubes 58. The housing 54 of the desiccant wheel 52
includes a first air inlet 62 in airflow communication with the
primary channel of the evaporative cooler for receiving the
evaporatively cooled airstream. The first air inlet 62 directs the
evaporatively cooled airstream through a first sector of the
desiccant tube 58 to pass over the solid desiccant material. The
presence of the evaporatively cooled airstream causes an exothermic
reaction with the solid desiccant material. As a result, moisture
from the evaporatively cooled airstream is adsorbed by the solid
desiccant material, thereby producing the dehumidified airstream.
The reaction is governed according to equation (1), wherein M
refers to the solid desiccant material, and the reaction adsorbs n
molecules of water vapor nH.sub.2O into the solid desiccant
material, forming a complex M.nH.sub.2O and liberating heat
Q.sub.o. This liberated heat can raise the temperature of air
flowing through the first section of the desiccant wheel 52.
M ( s ) + n H 2 O exothermic adsorption M n H 2 O + Q o ( 1 )
##EQU00001##
[0019] A first air outlet 64 is provided in airflow communication
with the evaporator air passage for directing the dehumidified
airstream over the evaporator tubes 24. This reaction leaves less
water vapor in the airstream that will condense in the evaporator
assembly 22, thereby reducing the latent load on the evaporator and
further reducing the overall cooling load on the system 20.
[0020] However, once the solid desiccant material absorbs the water
vapor, it must be regenerated. Therefore, a second air inlet 66 is
in airflow communication with the condenser air passage to receive
a second portion of the exhaust airstream. A second conduit 68
connects the condenser air passage with second air inlet 66 for
directing the second portion of the exhaust airstream to the
desiccant tubes 58. An exhaust flow divider 70 connects the
condenser air passage in airflow communication with the first and
second conduits 48, 68 for dividing the exhaust airstream into the
first portion and the second portion. According to the exemplary
embodiment, the exhaust flow divider 70 is a Y-shaped conduit that
connects the first and second conduits 48, 68 with the condenser
air passage. A heater 72 is provided in airflow communication
between the condenser air passage and the second air inlet 66 of
the desiccant wheel 52 for adding heat to the second portion of the
exhaust airstream.
[0021] The second portion of the exhaust airstream is directed from
the second air inlet 66 through a second sector of the desiccant
tubes 58. When the warm air from the heater 72 comes into contact
with the solid desiccant material, an endothermic reaction results,
which removes the water vapor molecules from the solid desiccant
material. This reaction is governed according to equation (2),
where the heat from the second portion of the exhaust airstream
replaces the heat Q.sub.o liberated during the exothermic
reaction:
M ( s ) + n H 2 O endothermic desportion M n H 2 O + Q o ( 2 )
##EQU00002##
[0022] A second air outlet 74 is provided to discharge the second
portion of the exhaust airstream after the endothermic
reaction.
[0023] The desiccant wheel 52 is supported by the trunnions 60 for
rotation about the axis Z to alternately move the solid desiccant
material between the first and second sectors to successively
expose the solid desiccant material to the second portion of the
exhaust airstream and to the evaporatively cooled airstream. This
cycle allows the solid desiccant material to be continually used
and regenerated. According to the exemplary embodiment, the
desiccant wheel 52 rotates at a speed of about 5-6 RPM. In
addition, the amount of moisture that can be absorbed by the
desiccant wheel 52 is proportional to the rotational speed, so the
humidity of the dehumidified airstream can be controlled simply by
altering the speed.
[0024] Referring to FIG. 4, the psychrometric properties of air
flowing through the system 20 are shown. The letters designating
points throughout the psychrometric chart of FIG. 4 correspond to
positions within the system 20 of FIG. 1. To wit, ambient air
enters the system 20 at point A, having an ambient temperature
T.sub.i and an absolute humidity .omega..sub.i. The ambient air is
heated in the condenser air passage, and leaves as exhaust
airstream at point B, having the same absolute humidity, and an
increased temperature T.sub.s, which increases the water vapor
uptake capacity of air both in the evaporative cooler assembly 36
and the desiccant wheel 52. The first portion of the exhaust
airstream then flows into the evaporative cooler and exits as the
evaporatively cooled airstream at point C, having the same absolute
humidity and reduced temperature T.sub.p. The moisture-laden
airstream exits the evaporative cooler assembly 36 through the
secondary channel at point D, having a slightly lower temperature
T.sub.SE, due to direct evaporative cooling in the secondary
channels, and increased absolute humidity .omega..sub.s. The
evaporatively cooled airstream in the primary channels then flows
into the desiccant wheel 52 and exits as the dehumidified airstream
at point E with an increased temperature that does not exceed the
ambient temperature T.sub.i, and a lower absolute humidity
.omega..sub.o. The dehumidified airstream then enters the
evaporator air passage and is further cooled to point F, having the
same absolute humidity and lower temperature T.sub.e. The second
portion of the exhaust airstream leaves the condenser air passage
and enters the heater 72. The second portion of the exhaust
airstream exits the heater 72 at point G, having the same absolute
humidity .omega..sub.i, and an increased temperature T.sub.d. The
second portion of the exhaust airstream then enters the desiccant
wheel 52 to dry the solid desiccant material, receives the moisture
from the solid desiccant material, and exits the desiccant wheel 52
at point H, having substantially the same temperature T.sub.d, and
higher absolute humidity .omega..sub.d.
[0025] The air conditioning system 20 utilizes the waste heat from
the condenser airstream to increase the water vapor uptake capacity
of air. Additionally, the condenser fan 33 performs multiple
functions, including directing air through the condenser assembly
30, evaporative cooler assembly 36, and the desiccant wheel 52,
rather than using a separate fan for each assembly.
[0026] Within the evaporative cooler assembly 36, the higher water
vapor uptake capacity of air flowing through the first conduit 48
and into the evaporative cooler assembly 36 increases the
evaporation rate of water in the secondary channel. A higher
evaporation rate translates into a more efficient evaporative
cooling process. Within the desiccant wheel 52 the higher water
vapor uptake capacity of air flowing through the second conduit 68
increases the desiccant material regeneration rate by absorbing a
greater amount of moisture from the solid desiccant material. Both
of these factors increase the overall efficiency of the air
conditioning system 20. The evaporatively cooled airstream leaving
the primary channel of the evaporative cooler assembly 36 absorbs
the heat of the exothermic reaction occurring within the desiccant
wheel 52 thereby delivering the dehumidified air to the evaporator
assembly 22 at or below ambient air temperature T.sub.i. Thus, the
evaporative cooler assembly 36 operating in conjunction with the
desiccant wheel 52 completely handles the latent load of the
evaporator assembly 22 with the expenditure of waste heat only,
thereby increasing the overall efficiency of the air conditioning
system 20. The load reduction achieved by the use of this waste
heat could be substantial, typically amounting to about 40% of the
total load.
[0027] While the invention has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
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