METHOD AND APPARATUS FOR CONDITIONING AIR
TECHNICAL FIELD
Various embodiments o f the invention relate t o
dehumif ication and humidif ication in heating, ventilating, and
air conditioning systems.
BACKGROUND
Heating, ventilating, and air-conditioning (HVAC)
systems provide temperature and humidity controlled air t o
residential, commercial, and industrial buildings. Air
provided b y the HVAC system may need t o b e a t a specified
temperature o r humidified o r dehumidified t o meet comfort
levels for occupancy, o r t o b e within a range for electronics,
o r the like. Typically outside air i s dehumidified and cooled
i f using an air conditioning system, and i t i s humidified and
heated i f using a heating system. The temperature and
humidity mechanisms may b e integrated o r separate.
For example, with some conventional air conditioning
systems, air i s cooled below its dew point b y passing i t over
cooling coils such that water i s condensed out o f the air.
This usually results in air a t a temperature below a comfort
zone temperature. The air i s then heated t o bring i t t o a
desired comfort zone temperature b y mixing i t with warmer air
already in the space being cooled o r b y passing i t over a
heating coil. The excess cooling used t o dehumidif y the air
decreases efficiency.
I f a desiccant type dehumidifier i s used in an air
conditioning system, the desiccant removes water t o dehumidify
air in the dehumidif ication section. The dried air can then
b e cooled using a cooling coil t o a desired comfort zone
temperature. The desiccant i s regenerated in a regeneration
section where water i s removed from the desiccant. The
desiccant can then b e reused in the dehumidif ication section.
Depending on the capacity and type o f the dehumidif ication and
regeneration sections, desiccant can b e blown out o f the
sections a t high air flow rates. A high flow rate o f air
flowing through the chamber containing the desiccant contacts
the desiccant, entrains desiccant droplets o r vapor, and
causes desiccant t o b e lost from the HVAC system. The loss o f
desiccant through blow-out from the chamber during high air
flow rate conditions can impair the function o f the
dehumidifier i f insufficient desiccant i s present, o r can
cause other problems .
SUMMARY
In some embodiments o f the invention, an apparatus
for conditioning air i s provided with a quantity o f liquid
desiccant. A first contact volume i s provided in which a
first portion o f a first airflow i s received such that i t
contacts a first portion o f the liquid desiccant. A second
contact volume i s in parallel with the first contact volume in
which a second portion o f the first airflow i s received. A
third contact volume i s provided in which a t least a portion
o f a second airflow i s brought into contact with a second
portion o f the liquid desiccant. A first heat exchanger i s
associated with the first portion o f the liquid desiccant and
configured t o transfer heat between the first portion o f the
liquid desiccant and a first medium. A second heat exchanger
i s associated with the second portion o f the liquid desiccant
and configured t o transfer heat between the second portion o f
the liquid desiccant and a second medium.
In another embodiment, an apparatus for conditioning
air i s provided with a first chamber having an inlet and an
outlet for a first flow o f a first fluid. The first chamber
contains a first portion o f a liquid desiccant for removing
water from the first flow moving through the chamber. A
second chamber has an inlet and an outlet for a first flow o f
a second fluid and contains a second portion o f the liquid
desiccant for evaporating water from the desiccant t o the
second fluid. The second chamber i s in fluid communication
with the first chamber such that the desiccant i s capable o f
flowing between the first and second chambers. A third
chamber has an inlet and an outlet for a second flow o f the
second fluid, and i s in parallel with the second chamber.
In yet another embodiment, a method o f conditioning
a fluid using a system having a first chamber, a second
chamber, and a third chamber i s provided. A first portion o f
a first fluid flows through the first chamber. The first
portion o f the first fluid interacts with a portion o f a
desiccant and transfers water between the first portion o f the
first fluid and the portion o f the desiccant. A second
portion o f a first fluid flows through the second chamber.
The second portion o f the first fluid bypasses the first
chamber. A second fluid flows through the third chamber. The
second fluid interacts with a t least a portion o f the
desiccant and transfers water between the second fluid and the
a t least a portion o f the desiccant. The first and second
portions o f the first fluid are combined after the first
portion o f the first fluid exits the first chamber and the
second portion o f the first fluid exits the second chamber.
In another embodiment, an apparatus for conditioning
air i s provided with a quantity o f liquid desiccant, a first
contact volume in which a first portion o f a first airflow i s
received such that i t contacts a first portion o f the liquid
desiccant, a second contact volume in parallel with the first
contact volume in which a second portion o f the first airflow
i s received, and a third contact volume in which a t least a
portion o f a second airflow i s brought into contact with a
second portion o f the liquid desiccant. A first heat
exchanger i s in contact with the first portion o f the liquid
desiccant and configured t o transfer heat between the first
portion o f the liquid desiccant and a first medium. A second
heat exchanger i s in contact with the second portion o f the
liquid desiccant and configured t o transfer heat between the
second portion o f the liquid desiccant and a second medium. A
vapor compression system includes a compressor, a third heat
exchanger not in contact with the liquid desiccant, and a
refrigerant .
BRIEF DESCRIPTION O F THE DRAWINGS
FIGURE 1 i s a schematic o f a unit for conditioning
air according t o an embodiment o f the invention; and
FIGURE 2 i s a schematic o f unit for conditioning air
according t o another embodiment o f the invention.
DETAILED DESCRIPTION
A s required, detailed embodiments o f the present
invention are disclosed herein; however, i t i s t o b e
understood that the disclosed embodiments are merely exemplary
o f the invention that may b e embodied in various and
alternative forms. The figures are not necessarily t o scale;
some features may b e exaggerated o r minimized t o show details
o f particular components. Therefore, specific structural and
functional details disclosed herein are not t o b e interpreted
a s limiting, but merely a s a representative basis for the
claims and/or a s a representative basis for teaching one
skilled in the art t o variously employ the present invention.
A heating, ventilating, and air conditioning (HVAC)
system 1 0 i s shown schematically in Figure 1 . The system 1 0
has a dehumidif ication section o r side 1 4 and a regeneration
section o r side 16, and uses a desiccant system 1 2 t o change
the humidity level o f air flowing through the system 10. The
dehumidif ication side 1 4 may b e used a s a dehumidifier t o
provide drier air, o r a s an air conditioner t o provide drier,
cooler air. Alternatively, the regeneration side 1 6 may b e
used a s a heating system t o provide warmer, higher humidity
air. The desiccant i s a lithium chloride salt solution.
Alternatively, the desiccant includes lithium bromide,
magnesium chloride, calcium chloride, sodium chloride, o r the
like .
The desiccant system 1 2 has a dehumidif ication
chamber 1 8 on the dehumidif ication side 1 4 o f the system 10,
where a desiccant within the chamber 1 8 absorbs water from air
flowing through the chamber 1 8 and contacting the desiccant.
The air flowing through the chamber 1 8 i s provided through an
air inlet 2 0 t o the dehumidif ication side 14. Only a portion
o f air entering through inlet 2 0 flows through the
dehumidif ication chamber 18, and the remainder o f air bypasses
the chamber 1 8 and flows through ducting parallel t o the
dehumidif ication chamber 1 8 thus allowing for higher flow
rates required t o achieve the desired cooling in a given space
o r better control o f the humidity level o f the air exiting the
dehumidif ication side 14. Alternatively, all o f the air
entering through inlet 2 0 flows through the dehumidif ication
chamber 18 .
The desiccant system 1 2 also has a regeneration
chamber 2 2 on the regeneration side 1 6 o f the system 10, where
water i s removed from the desiccant through absorption into
air flowing through the chamber 22. The air flowing through
the chamber 2 2 i s provided through an air inlet 2 4 t o the
regeneration side 16. Only a portion o f air entering through
inlet 2 4 flows through the regeneration chamber 22, and the
remainder o f air bypasses the chamber 2 2 and flows through
ducting parallel t o the chamber 22, thus allowing for higher
air flow rates o r better control o f the humidity o f air
exiting the regeneration side 16. Alternatively, all o f the
air entering through inlet 2 4 flows through the regeneration
chamber 2 2 .
The dehumidif ication chamber 1 8 and the regeneration
chamber 2 2 are connected such that a liquid desiccant may flow
between the two. The desiccant with a higher water content
from the dehumidif ication chamber 1 8 i s exchanged with
desiccant with a lower o r n o water content from the
regeneration chamber 22. The desiccant i s transported via
diffusion flow from differences in desiccant concentration,
pumped flow using one o r more pumps, gravitational flow using
a controlled overflow, o r the like.
Moist air flows through inlet 2 0 and through the
dehumidif ication, o r process, side 14. Inlet 2 0 draws air
from inside a building o r draws outside air t o add t o a
building HVAC system. A fan (not shown) o r other device i s
used t o create a pressure difference t o provide the air flow
through the side 14. A set o f dampers, o r additional fans,
divides and controls the air flow from the inlet 2 0 into two
air streams.
One o f the air streams from the inlet 2 0 flows
through the dehumidif ication chamber 1 8 where water i s removed
from the air b y the desiccant. The desiccant i s a liquid
desiccant and may b e sprayed, contained on a sponge like
material, o r used a s i s known in the art t o dehumidify the air
stream. The stream o f air flowing through the
dehumidif ication chamber 1 8 leaves the chamber 1 8 with a lower
water content, a s a dry air portion.
The other portion o f air from inlet 2 0 i s cooled b y
a heat exchanger 26, such a s a cold water coil o r a glycol
coil. The heat exchanger 2 6 may b e directly connected t o a
groundwater source, o r may b e integrated into a larger cooling
system 2 8 o r thermodynamic system 29, such a s a vapor
compression cycle. The dry air portion and the other cooled
portion o f air are recombined before exiting the
dehumidif ication side 14. Heat exchanger 3 0 i s a part o f the
vapor compression cycle 29, o r alternatively, i s connected t o
a ground water source and integrated into cooling system 28.
The heat exchanger 3 0 i s located on the regeneration side 1 6
t o keep the lines in vapor compression cycle 2 9 on the
regeneration side 16, and out o f the dehumidif ication side 14.
The air flow i s conditioned on the dehumidif ication side 1 4
through cooling and the removal o f water moisture. Vapor
compression cycle 2 9 has a compressor 3 1 t o circulate a
refrigerant fluid through the cycle 29, and additionally has a
throttle (not shown) . The heat exchangers described within
the system 1 0 are associated with a medium such a s various
flows o f air, desiccant, o r circulating fluids, meaning that
there i s either direct heat transfer between a fluid flowing
through the heat exchanger and the medium o r there i s indirect
heat transfer between the fluid flowing through the heat
exchanger and the medium using intermediary heat exchangers o r
additional mediums.
Alternatively, after the water removal in the
dehumidif ication chamber 18, the dry air portion and the other
portion o f air from inlet 2 0 are recombined and then flow
across and are cooled b y a medium flowing in the heat
exchanger 26.
B y reducing the air flow through the chamber 1 8 b y
providing a bypassed air portion, blow-out o f desiccant from
the chamber 1 8 i s prevented o r reduced and higher flow rates
are attainable. The flow rate through the chamber 1 8 i s
limited based on when the air flowing through the chamber
begins t o entrain desiccant. The flow rate o f air through the
dehumidif ication side 1 4 i s increased b y bypassing air around
the chamber 18, thereby providing an air flow that i s greater
than what i s attainable using the chamber 1 8 alone.
I f a cooling system 2 8 i s present, a flow o f cooling
fluid, such a s glycol o r another refrigerant, leaves the heat
exchanger 3 0 and flows in parallel o r in series t o heat
exchanger 2 6 and heat exchanger 32. The cooling fluid in heat
exchanger 3 2 may b e used t o cool the desiccant before use in
the dehumidif ication chamber 18, which additionally cools the
air .
A second flow o f air enters through inlet 2 4 and
through the regeneration side 1 6 o f the system 10. Inlet 2 4
may draw air from outside a building i f the system 1 0 i s used
a s an air conditioning system. A fan (not shown) o r other
device i s used t o create a pressure difference t o provide the
air flow through side 16. The air i s preheated b y a medium in
heat exchanger 3 4 before i t enters the regeneration chamber 2 2
containing the desiccant. The air i s preheated t o increase
the amount o f water that may b e evaporated into the air from
the desiccant. Heat exchanger 3 4 i s a part o f the vaporcompression cycle 29, o r alternatively, i s connected t o an
external heat source. The air flows through the regeneration
chamber 2 4 where water i s removed from the desiccant. The
desiccant may b e sprayed, contained on a sponge like material,
o r used otherwise a s i s known in the art. The desiccant i s
heated b y a medium in heat exchanger 3 6 before entering the
regeneration chamber 2 2 t o aid in the evaporation water from
the desiccant. Heat exchanger 3 6 i s connected into vapor
compression cycle 29, o r alternatively, i s connected t o an
external heat source. The heated air flowing through the
regeneration chamber 2 2 leaves the chamber 2 2 a s moist air
with an increased water content.
In an embodiment, a set o f dampers, o r additional
fans, divides the air flow through inlet 2 4 into two air
streams, often after the heat exchanger 34. One o f the air
streams flows through the regeneration chamber 22, while the
other air stream bypasses the chamber 22. B y limiting the air
flow through the chamber 22, blow-out o f desiccant from the
chamber 2 2 i s prevented o r reduced. The flow rate o f air
through the regeneration side 1 6 i s increased b y bypassing air
around the chamber 22, thereby providing an air flow that i s
greater than what i s attainable using the chamber 2 2 alone.
The two air streams may b e recombined in a mixing chamber o r
the like downstream o f the regeneration chamber 22.
The system 1 0 i s described previously a s an air
conditioning unit where the dehumidif ication side 1 4 provides
a high flow rate o f cooler air a t an appropriate humidity
level t o a building, and the regeneration side 1 6 i s used t o
cycle desiccant for reuse in the desiccant system 12. In
other embodiments, the system 1 0 a s described above i s used a s
a heating unit with the regeneration side 1 6 providing a high
flow rate o f warmer air a t an appropriate humidity level t o a
building, and the dehumidif ication side cycling the desiccant
for reuse in the desiccant system 12. The system 1 0 may b e
used t o provide air a s a HVAC system using the side 14, 1 6
which corresponds t o the HVAC purpose o r requirements.
Figure 2 illustrates another HVAC system 5 0 having a
dehumidif ying chamber 5 2 and a regenerator unit 54. The
dehumidif ying chamber 5 2 and the regenerator unit 5 4 provide
chambers o r contact volumes where air interacts and comes into
contact with a desiccant. In one embodiment, the system 5 0
provides cooler, drier, conditioned air from the dehumidif ying
chamber 52, while the desiccant i s regenerated in unit 5 4 for
reuse. In another embodiment, the system 5 0 provides warmer,
moister, conditioned air from the regenerator unit 54, while
the desiccant i s regenerated using the chamber 5 2 for reuse.
The system 5 0 i s described below a s an air conditioning unit;
however, the use o f the system a s a heater o r ventilator i s
contemplated and functionally would also operate a s described
below. Differences between the system 5 0 a s an air
conditioner and a s a heater are the sources o f inlet air for
the chamber 5 2 and the unit 54, and where the air from the
chamber 5 2 and unit 5 4 i s directed after leaving the system
5 0 .
Moist air enters the dehumidif ying chamber 5 2
through a moist air inlet 56, and cooler, dried air o r
partially dried air exits chamber 5 2 through a dry air outlet
58. A bypass duct 6 0 allows a portion o f the air entering
through inlet 5 6 t o b e bypassed around the dehumidif ying
chamber 52. The bypass duct 6 0 acts a s a chamber o r contact
volume for the bypassed portion o f air. A series o f fan o r
dampers 6 2 control the relative portions o f air flowing
through the chamber 5 2 and the duct 60. The respective
portions o f air may b e recombined using a mixing chamber 6 4
downstream o f the chamber 5 2 and the duct 60. The bypass duct
6 0 allows for a higher flow rate o f air (cubic feet per
minute, cfm) t o b e provided b y outlet 5 8 and t o flow through
the system 50. The addition o f the duct 6 0 provides a
mechanism t o obtain higher overall flow rates a t outlet 58,
while maintaining air flow through the chamber 5 2 a t a lower
flow rate. The flow rate through chamber 5 2 i s limited b y
when the desiccant begins t o b e entrained b y the air flowing
through the chamber 52. Without a bypass duct 6 0 and a t high
flow rates, desiccant from chamber 5 2 blows out o f the chamber
and i s entrained in the exiting air a t outlet 58.
Desiccant 6 6 i s pumped from a desiccant reservoir 7 0
through a pipe 7 2 t o a series o f nozzles 7 4 using a pump 68.
The nozzles 7 4 spray the desiccant into the interior o f
chamber 52. The chamber 5 2 may b e filled with a cellulose
sponge material through which the desiccant percolates
downward t o the reservoir 70. The portion o f moist air
entering the chamber 5 2 through inlet 5 6 contacts the
desiccant droplets. The hygroscopic desiccant absorbs water
vapor from the moist air. Drier air exits the chamber 52,
mixes with the bypass air from duct 60, and exits through
outlet 58.
The desiccant in the sump 7 0 connected t o chamber 5 2
increases in water content a s air i s dried. The desiccant i s
regenerated for reuse b y having water removed from i t in a
regeneration unit 54. Air enters through inlet 7 6 o f the
regeneration unit 5 4 and exits through outlet 78. The air
flow may b e divided into two portions, with one portion
flowing through the regeneration unit 54, and the other
portion flowing through a bypass duct 80. The bypass duct 8 0
acts a s a chamber o r contact volume for the bypassed portion
o f air. A series o f dampers 8 2 o r fans are used t o control
the relative portions o f air between the unit 5 4 and the duct
80. The portion o f air flowing through the unit 5 4 carries
away moisture evaporated from the desiccant through outlet 78.
The portions o f air flowing through the unit 5 4 and the bypass
duct 6 0 may b e recombined in a mixing chamber 8 4 before
exiting the outlet 78.
Desiccant 6 6 i s pumped b y a pump 8 6 from a desiccant
reservoir 8 8 through a pipe 9 0 t o a series o f nozzles 92. The
nozzles 9 2 spray the desiccant into the interior o f unit 54,
which may b e filled with a cellulose sponge material through
which the desiccant percolates downward t o reservoir 88. The
portion o f air entering the unit 5 4 through inlet 7 6 contacts
the moisture laden desiccant droplets. Water vapor i s
evaporated from the desiccant into the drier air, and moist
air exits the chamber 54, mixes with the bypass air, and exits
through outlet 78. B y reducing the water content in the
desiccant, the desiccant 6 6 i s regenerated for reuse in the
dehumidif ying chamber 52.
The bypass duct 8 0 allows for a higher flow rate o f
air (cubic feet per minute, cfm) t o b e provided b y outlet 78.
The addition o f the duct 8 0 provides a mechanism t o obtain
higher overall flow rates a t outlet 78, while maintaining air
flow through the unit 5 4 a t a lower flow rate which prevents
desiccant from becoming entrained into the air flowing through
the unit 54. Without a bypass duct 8 0 and a t high air flow
rates, desiccant may blow-out o f unit 5 4 and b e entrained in
the exiting air.
A heat transfer mechanism often occurs between the
desiccant flowing through the dehumidif ying side and the
regenerative side. For example, a vapor compression cycle 94,
such a s a heat pump o r refrigeration cycle, i s used for the
heat transfer between the high and low water content
desiccants and i s additionally used t o cool o r heat air
flowing through the system 50. O f course, other cycles o r
heat exchangers operating independently using heat sources and
sinks are also contemplated. The heat exchangers described
within the system 5 0 are associated with a medium such a s
various flows o f air, desiccant, o r circulating fluids,
meaning that there i s either direct heat transfer between two
mediums flowing through the heat exchanger o r there i s
indirect heat transfer between two mediums flowing through the
heat exchanger through intermediary heat exchangers o r
additional mediums.
The vapor compression cycle 9 4 includes a compressor
96, a first condenser 98, a second condenser 100, a throttle
o r expansion valve 102, and an evaporator 102. The heat pump
9 4 uses a refrigerant such a s R-134a, R-1234, o r others a s are
known in the art. The compressor 9 6 circulates the
refrigerant through the cycle 94. The first condenser 9 8 acts
a s a heat exchanger t o heat the desiccant in pipe 98. B y
preheating the desiccant before regenerating i t in unit 54,
water i s more easily evaporated from the desiccant. The
second condenser 100 acts a s a heat exchanger t o heat the air
flowing through inlet 76. Warmer air flowing through unit 5 4
i s able t o retain a higher level o f moisture o r water a t a
higher temperature, which additionally assists regeneration o f
the desiccant 66. The evaporator 104 provides a heat
exchanger which acts a s a heat sink t o directly o r indirectly
cool desiccant and air on the dehumidif ying side o f the system
5 0 .
The order o f the first and second condensers 98, 100
may b e reversed depending on the heating requirements o f the
air and the desiccant. Additionally, the second heat
exchanger 100 could b e positioned t o heat only the portion o f
air flowing through the unit 54, a s opposed t o the air flowing
through inlet 76.
The evaporator 104 may b e a two-stage evaporator, o r
two evaporators in series t o directly cool the desiccant and
the air on the dehumidif ying side o f the system 50.
Alternatively, the evaporator 104 i s connected t o a cooling
loop 106, which contains glycol, water, o r another fluid.
Flow within the cooling loop 106 leaves the evaporator 104,
and divides a t valve 108. One line in the cooling loop 106
flows through a heat exchanger 110, which i s directly o r
indirectly in contact with the desiccant in the pipe 7 2 t o
pre-cool the desiccant before i t enters chamber 52. The other
line in the cooling loop 106 flows through a heat exchanger
112, in parallel with the first heat exchanger 110. The
medium in the heat exchanger 112 cools the air in the bypass
duct 60. B y cooling the air in the bypass duct, cooler moist
air from duct 6 0 i s mixed with drier air from chamber 5 2 a t
mixing chamber 64, which allows for control over the air
temperature and humidity level a t outlet 5 8 through use o f the
dampers 62, fans, and a controller (not shown) . Heat
exchanger 112 may also b e positioned a t inlet 5 6 t o cool all
o f the air flowing through the dehumidif ying side o f the
system 50. Other cooling loops 106 are also contemplated,
such a s those having heat exchangers in series.
Cooling the desiccant on the dehumidif ying side with
heat exchanger 110, reduces the temperature o f the desiccant
in chamber 52, which contacts the air being dried in the
chamber 5 2 and additionally reduces the temperature o f the
dried air.
Alternatively, the heat exchangers in the vapor
compression cycle 9 4 and cooling loop 106 may b e directly
plumbed t o heat sinks o r sources, such a s groundwater o r waste
heat from an associated air-conditioner o r other system.
Desiccant may b e transferred between the two
reservoirs 70, 8 8 using a diffusive aperture 114, pumps, a
float system, o r the like. Desiccant in reservoir 7 0
increases in water content a s the dehumidif ying chamber 5 2
operates compared t o the desiccant in reservoir 88, which
equates t o a higher concentration o f desiccant in reservoir 8 8
than in reservoir 70. The desiccant needs t o b e regenerated
for the efficiency and drying capacity o f the dehumidif ying
chamber 5 2 .
In the system 5 0 a s shown in Figure 2 , the desiccant
i s transferred between the dehumidif ying reservoir 7 0 and the
regeneration reservoir 8 8 through diffusion transport.
Alternatively, pumping o r another system may b e used.
Aperture 114 allows for transfer o f ions o f water and
desiccant salt between the reservoirs while minimizing the
amount o f heat transfer between the reservoirs. The
dehumidif ying chamber 5 2 continuously adds water content t o
the desiccant 6 6 in the reservoir 70. The regenerating unit
5 4 continuously removes water from the desiccant. During
operation, the concentration o f salt ions in the reservoir 8 8
i s generally higher than that in reservoir 7 0 because the
desiccant the regeneration reservoir 8 8 i s being concentrated
while the desiccant in reservoir 7 0 i s being diluted. The
difference in concentration causes a flow o f salt ions from
reservoir 8 8 t o reservoir 7 0 b y diffusive transport, through
aperture 114, which i s balanced b y the flow o f water ions from
reservoir 7 0 t o reservoir 8 8 caused b y the flow o f solution in
this direction. This results in steady state levels o f
desiccant concentrations, although during changing air flow
rate, start up conditions, o r other system 5 0 transients,
there will b e corresponding transient period for the desiccant
concentrations.
In one embodiment, the system 5 0 has a dehumidif ying
chamber (or contact volume) 5 2 and a regeneration chamber 54.
A bypass duct (or contact volume) 6 0 i s provided in parallel
with the dehumidif ying chamber 52. Liquid desiccant 6 6 i s
used in the chambers 52, 5 4 t o change the humidity level o f
air flowing through the chambers 52, 54. A portion o f an
airflow entering inlet 5 6 flows into chamber 5 2 such that i t
contacts a first portion o f the liquid desiccant 6 6 and i s
dehumidified. A second portion o f an airflow entering inlet
5 6 flows through the bypass duct 60. A t least a portion o f a
second airflow entering through inlet 7 6 flows into chamber 5 4
such that i t contact a second portion o f the liquid desiccant
6 6 and water i s removed from the desiccant t o regenerate the
desiccant. The system 5 0 has a heat exchanger 110 in contact
with the first portion o f the liquid desiccant 66. Another
heat exchanger 9 8 i s in contact with the second portion o f the
liquid desiccant 66. Yet another heat exchanger 112 i s not in
contact with the liquid desiccant 66. In one embodiment, the
heat exchanger 112 i s in contact with the second portion o f
the first airflow in bypass duct 60. In some embodiments, the
system has a vapor compression system 9 4 including heat
exchangers 110, 98, 112, a compressor 96, and a refrigerant.
In other embodiments, the heat exchangers 110, 112, 9 8 may b e
run t o independent heat sources o r sinks. Alternatively, the
heat exchangers 110, 112 are a part o f a cooling loop 106 in
communication with the vapor compression cycle 94. Heat
exchangers 110, 112 are arranged in parallel such that the
refrigerant o r cooling fluid flows in parallel t o the heat
exchangers 100, 112.
Heat exchanger 110 transfers heat from the desiccant
6 6 t o the vapor compression cycle 94. Heat exchanger 112
transfers heat from the bypass air in duct 6 0 t o the vapor
compression cycle 94. This provides two sources o f heat t o
the vapor compression cycle 94, the bypass air in duct 6 0 and
the desiccant flowing through piping 72. The increased energy
transferred into the vapor compression leads t o additional
energy (or heat) that may b e transferred o r used on the
regeneration side, increasing the heat capacity available for
regeneration. This additionally increases the system 5 0
efficiency and allows for higher airflows through the system
50. B y arranging the heat exchangers 110, 112 in parallel, a
higher airflow may b e attained through inlet 5 6 and outlet 5 8
without blow-out o f the desiccant 6 6 from the chamber 52.
While embodiments o f the invention have been
illustrated and described, i t i s not intended that these
embodiments illustrate and describe all possible forms o f the
invention. Rather, the words used in the specification are
words o f description rather than limitation, and i t i s
understood that various changes may b e made without departing
from the spirit and scope o f the invention. Additionally,
features o f various implementing embodiments may b e combined
t o form further embodiments o f the invention.
WHAT I S CLAIMED:
1 . Apparatus for conditioning air comprising:
a quantity o f liquid desiccant;
a first contact volume in which a first portion o f a
first airflow i s received such that i t contacts a first
portion o f the liquid desiccant;
a second contact volume in parallel with the first
contact volume in which a second portion o f the first airflow
i s received;
a third contact volume in which a t least a portion
o f a second airflow i s received such that i t contacts a second
portion o f the liquid desiccant;
a first heat exchanger associated with the first
portion o f the liquid desiccant and configured t o transfer
heat between the first portion o f the liquid desiccant and a
first medium; and
a second heat exchanger associated with the second
portion o f the liquid desiccant and configured t o transfer
heat between the second portion o f the liquid desiccant and a
second medium.
2 . The apparatus o f claim 1 further comprising
fourth contact volume in parallel with the third contact
volume in which a second portion o f the second airflow i s
received .
3 . The apparatus o f claim 1 further comprising a t
least one damper t o control relative amounts o f the first and
second portions o f the first airflow flowing t o the first and
second contact volumes, respectively.
. The apparatus o f claim 1 wherein the first heat
exchanger i s also associated with the second portion o f the
first airflow in the second contact volume and configured t o
transfer heat between the second portion o f the first airflow
and the first medium.
5 . The apparatus o f claim 1 further comprising a
vapor compression system including the first heat exchanger,
the second heat exchanger, and a compressor;
wherein the first medium i s the same a s the second
medium.
6 . The apparatus o f claim 1 further comprising a
cooling loop having a cooling fluid circulating therethrough,
the cooling loop being in communication with the first heat
exchanger, the cooling loop having:
a third heat exchanger in communication with
the first portion o f the liquid desiccant and configured t o
transfer heat between the first portion o f the liquid
desiccant and the cooling fluid; and
a fourth heat exchanger in communication with
the second portion o f the first airflow and configured t o
transfer heat between the second portion o f the first airflow
and the cooling fluid.
7 . The apparatus o f claim 1 further comprising
mixing chamber downstream o f the first and second contact
volumes for combining the first and second portions o f the
first airflow.
8 . The apparatus o f claim 1 further comprising a
third heat exchanger in communication with the a t least a
portion o f the second airflow before i t flows into the third
contact volume, the third heat exchanger configured t o
transfer heat between the a t least a portion o f the second
airflow and a third medium.
9 . The apparatus o f claim 1 further comprising a
third heat exchanger associated with the second portion o f the
first airflow and configured t o transfer heat between the
second portion o f the first airflow and a third medium.
10. Apparatus for conditioning air comprising:
a first chamber having an inlet and an outlet for a
first flow o f a first fluid, the first chamber containing a
first portion o f a liquid desiccant for removing water from
the first flow moving through the chamber;
a second chamber having an inlet and an outlet for a
first flow o f a second fluid, the second chamber containing a
second portion o f the liquid desiccant for evaporating water
from the desiccant t o the second fluid, the second chamber in
fluid communication with the first chamber such that the
desiccant i s capable o f flowing between the first and second
chambers; and
a third chamber having an inlet and an outlet for a
second flow o f the second fluid, the third chamber in parallel
with the second chamber.
11. The apparatus o f claim 1 0 further comprising
common inlet for the second fluid; and
a flow divider positioned within the common inlet
for the second fluid, and being adapted t o partition the
second fluid between the first flow o f the second fluid
through the inlet t o the second chamber and the second flow o f
the second fluid through the inlet t o the third chamber.
12. The apparatus o f claim 1 0 further comprising a
fourth chamber having an inlet and an outlet for a second flow
o f the first fluid, the fourth chamber in parallel with the
first chamber.
13. The apparatus o f claim 1 2 further comprising a
common inlet for the first fluid; and
a flow divider positioned within the common inlet
for the first fluid, and being adapted t o partition the first
fluid between the first flow o f the first fluid through the
inlet t o the first chamber and the second flow o f the first
fluid through the inlet t o the fourth chamber.
14. The apparatus o f claim 1 2 further comprising a
mixing chamber in communication with the outlet o f the first
chamber and the outlet o f the fourth chamber for combining the
first flow and the second flow o f the first fluid.
15. The apparatus o f claim 1 0 further comprising:
a first heat exchanger associated with the first
portion o f the liquid desiccant and configured t o transfer
heat between the first portion o f the liquid desiccant and a
first medium; and
a second heat exchanger associated with the second
portion o f the liquid desiccant and configured t o transfer
heat between the second portion o f the liquid desiccant and a
second medium.
16. The apparatus o f claim 1 5 further comprising a
cooling loop containing a cooling fluid circulating
therethrough, the cooling loop being associated with the first
heat exchanger, the cooling loop having:
a third heat exchanger in communication with
the first portion o f the liquid desiccant and configured t o
transfer heat between the first portion o f the liquid
desiccant and the cooling fluid; and
a fourth heat exchanger in communication with
the second flow o f the first fluid and configured t o transfer
heat between the second flow o f the first fluid and the
cooling fluid.
17. The apparatus o f claim 1 6 wherein the fourth
heat exchanger i s in parallel with the third heat exchanger in
the cooling loop.
18. The apparatus o f claim 1 6 wherein the cooling
loop has a valve configured t o vary the amount o f cooling
fluid flowing t o the third and fourth heat exchangers.
19. The apparatus o f claim 1 6 further comprising a
fifth heat exchanger associated with the first flow and second
flow o f the second fluid and configured t o transfer heat
between the first flow and second flow o f the second fluid and
a third medium.
20. A method o f conditioning a fluid using a system
having a first chamber, a second chamber, and a third chamber,
the method comprising:
flowing a first portion o f a first fluid through the
first chamber, the first portion o f the first fluid
interacting with a portion o f a desiccant and transferring
water between the first portion o f the first fluid and the
portion o f the desiccant;
flowing a second portion o f a first fluid through
the second chamber, the second portion o f the first fluid
bypassing the first chamber;
flowing a second fluid through the third chamber,
the second fluid interacting with a t least a portion o f the
desiccant and transferring water between the second fluid and
the a t least a portion o f the desiccant; and
combining the first and second portions o f the first
fluid after the first portion o f the first fluid exits the
first chamber and the second portion o f the first fluid exits
the second chamber.
21. Apparatus for conditioning air comprising:
a quantity o f liquid desiccant;
a first contact volume in which a first portion o f a
first airflow i s received such that i t contacts a first
portion o f the liquid desiccant;
a second contact volume in parallel with the first
contact volume in which a second portion o f the first airflow
i s received;
a third contact volume in which a t least a portion
o f a second airflow i s brought into contact with a second
portion o f the liquid desiccant;
a first heat exchanger in contact with the first
portion o f the liquid desiccant and configured t o transfer
heat between the first portion o f the liquid desiccant and a
first medium;
a second heat exchanger in contact with the second
portion o f the liquid desiccant and configured t o transfer
heat between the second portion o f the liquid desiccant and a
second medium; and
a vapor compression system including a compressor, a
third heat exchanger not in contact with the liquid desiccant,
and a refrigerant.
22. The apparatus o f claim 2 1 wherein the third
heat exchanger i s in contact with the second portion o f the
first airflow and i s configured t o transfer heat between the
second portion o f the first airflow and the refrigerant.
23. The apparatus o f claim 2 1 wherein the vapor
compression system includes the first heat exchanger and the
second heat exchanger;
wherein the refrigerant i s the first medium and the
second medium.
24. The apparatus o f claim 2 3 wherein the
refrigerant flows in parallel t o the second heat exchanger and
the third heat exchanger.