U.S. patent application number 14/241254 was filed with the patent office on 2015-09-17 for desiccant-based cooling system.
This patent application is currently assigned to DUCOOL, LTD.. The applicant listed for this patent is Dan Forkosh. Invention is credited to Dan Forkosh.
Application Number | 20150260420 14/241254 |
Document ID | / |
Family ID | 46796786 |
Filed Date | 2015-09-17 |
United States Patent
Application |
20150260420 |
Kind Code |
A1 |
Forkosh; Dan |
September 17, 2015 |
DESICCANT-BASED COOLING SYSTEM
Abstract
A desiccant-based system and method for conditioning air
includes a first unit remotely located from an area whose
environment is to be controlled. Additional units are respectively
located within areas where air conditioning is desired. Each of the
additional units is connected to the first unit such that desiccant
can be transferred between each of the additional units and the
first unit. Cool, undiluted desiccant can be transferred from the
first unit to at least one of the additional units so that ambient
air at the location of the additional unit can be dehumidified and
cooled. Each of the additional units are separately controllable,
such that the respective environments surrounding the additional
units can be maintained at different levels of humidity and
temperature.
Inventors: |
Forkosh; Dan; (Atlit,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Forkosh; Dan |
Atlit |
|
IL |
|
|
Assignee: |
DUCOOL, LTD.
Hoff Hacarmel
IL
|
Family ID: |
46796786 |
Appl. No.: |
14/241254 |
Filed: |
August 27, 2012 |
PCT Filed: |
August 27, 2012 |
PCT NO: |
PCT/US2012/052431 |
371 Date: |
April 8, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61527904 |
Aug 26, 2011 |
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Current U.S.
Class: |
62/94 ;
62/271 |
Current CPC
Class: |
B01D 2252/10 20130101;
B01D 53/263 20130101; F24F 2003/1458 20130101; B01D 2259/4508
20130101; B01D 53/1425 20130101; F24F 3/1417 20130101 |
International
Class: |
F24F 3/14 20060101
F24F003/14 |
Claims
1. A system for conditioning air, comprising: a first unit housing
a regenerator operable to receive a first airflow and bring the
first airflow into contact with a liquid desiccant to transfer
water from the liquid desiccant to the first airflow, the
regenerator including a regenerator sump for collecting the liquid
desiccant after water is transferred to the liquid desiccant from
the first airflow, the first unit further housing a first portion
of a process sump fluidly connected to the regenerator sump; and a
second unit remotely located from the first unit and configured to
receive a second airflow and bring the second airflow into contact
with the liquid desiccant, the second unit housing a second portion
of the process sump for collecting the liquid desiccant after it
contacts the second airflow, the first unit being in selective
fluid communication with the second unit such that the liquid
desiccant can be selectively transferred between the first and
second portions of the process sump, and the liquid desiccant
transferred from the second portion of the process sump to the
first portion of the process sump can be admixed with the liquid
desiccant in the regenerator sump prior to the liquid desiccant
being returned to the second unit.
2. The system of claim 1, wherein the regenerator sump and the
first portion of the process sump are separated by a divider having
an aperture disposed therein for facilitating diffusion of the
liquid desiccant therebetween.
3. The system of claim 1, wherein the first unit is located outside
a building and is configured to receive and exhaust the first
airflow from and to an ambient outdoor environment, and the second
unit is located inside the building and is configured to receive
and exhaust the second airflow from and to an ambient environment
inside the building.
4. The system of claim 1, wherein the first and second units are
operable in a first mode of operation to transfer water from the
second airflow to the liquid desiccant, and in a second mode of
operation to transfer water from the liquid desiccant to the second
airflow, when the second airflow is brought into contact with the
liquid desiccant in the second unit.
5. The system of claim 4, wherein the regenerator is configured to
be shut down during the second mode of operation to inhibit
evaporation of water from the liquid desiccant in the regenerator
sump.
6. The system of claim 4, wherein the first unit further houses at
least a portion of a refrigeration system configured to selectively
heat and cool the liquid desiccant through heat transfer with a
refrigerant.
7. The system of claim 6, wherein the first unit houses at least an
evaporator of the refrigeration system, and includes a first
process pump configured to pump the liquid desiccant from the first
portion of the process sump through the evaporator during the first
mode of operation to transfer heat from the liquid desiccant to the
refrigerant prior to the liquid desiccant being transferred to the
second unit and brought into contact with the second airflow.
8. The system of claim 7, further comprising a bypass valve
configured to return a portion of the liquid desiccant leaving the
evaporator to the first portion of the process sump prior to the
liquid desiccant being transferred to the second unit.
9. The system of claim 6, wherein the first unit includes a
regenerator pump configured to pump the liquid desiccant from the
regenerator sump through a condenser of the refrigeration system
during the first mode of operation to receive heat from the
refrigerant prior to being brought into contact with the first
airflow.
10. The system of claim of claim 9, wherein the refrigeration
system further includes a second condenser configured to further
cool the refrigerant prior to an expansion phase of the
refrigerant.
11. A system for conditioning air, comprising: a first unit
remotely located from an indoor space; and a second unit located
within the indoor space and in selective fluid communication with
the first unit, the first unit including a regeneration chamber
into which a first airflow is introduced and contacted with a
liquid desiccant to transfer water from the liquid desiccant to the
first airflow, the regeneration chamber including a regenerator
sump for collecting the liquid desiccant after water is transferred
to the liquid desiccant from the first airflow, the first unit
further including a first process chamber separated from the
regenerator chamber such that the first airflow is inhibited from
entering the first process chamber, the first process chamber
including a first portion of a process sump fluidly connected to
the regenerator sump, the second unit including a second process
chamber into which a second airflow is introduced and contacted
with the liquid desiccant to transfer water between the second
airflow and the liquid desiccant prior to the second airflow being
discharged into the indoor space, the second process chamber
including a second portion of the process sump for collecting the
liquid desiccant after it contacts the second airflow, the
selective fluid communication between the first and second units
providing selective transfer of the liquid desiccant between the
first and second portions of the process sump.
12. The system of claim 11, further comprising a plurality of the
second units, each located within a respective indoor space and
each in selective fluid communication with the first unit.
13. The system of claim 11, wherein the regenerator chamber and the
first process chamber are separated by a divider having an aperture
disposed between the regenerator sump and the first portion of the
process sump for facilitating diffusion of the liquid desiccant
therebetween.
14. The system of claim 11, wherein the first and second units are
operable in a first mode of operation to transfer water from the
second airflow to the liquid desiccant, and in a second mode of
operation to transfer water from the liquid desiccant to the second
airflow, when the second airflow is brought into contact with the
liquid desiccant in the second unit.
15. The system of claim 14, wherein the first unit further houses
at least a portion of a refrigeration system configured to
selectively heat and cool the liquid desiccant through heat
transfer with a refrigerant.
16. The system of claim 15, wherein the first unit houses at least
an evaporator of the refrigeration system, the first process
chamber including a first process pump configured to pump the
liquid desiccant from the first portion of the process sump through
the evaporator during the first mode of operation to transfer heat
from the liquid desiccant to the refrigerant prior to the liquid
desiccant being transferred to the second unit and brought into
contact with the second airflow.
17. The system of claim 16, further comprising a bypass valve
configured to return a portion of the liquid desiccant leaving the
evaporator to the first portion of the process sump prior to the
liquid desiccant being transferred to the second unit, thereby
allowing the first portion of the process sump to retain the cooled
desiccant.
18. The system of claim 17, wherein the regeneration chamber
includes a regenerator pump configured to pump the liquid desiccant
from the regenerator sump through a condenser of the refrigeration
system during the first mode of operation to receive heat from the
refrigerant prior to being brought into contact with the first
airflow.
19. A method for conditioning air, comprising: bringing a first
airflow into contact with a liquid desiccant in a regeneration
chamber to transfer water from the liquid desiccant to the first
airflow during a first mode of operation; collecting the liquid
desiccant in a regenerator sump after water is transferred from the
liquid desiccant to the first airflow; admixing the liquid
desiccant in the regenerator sump with liquid desiccant in a first
portion of a process sump disposed in a first process chamber
adjacent the regeneration chamber; transferring some of the liquid
desiccant from the first portion of the process sump to a second
portion of the process sump disposed in a second process chamber
located remotely from the first process chamber; bringing a second
airflow into contact with the liquid desiccant in the second
process chamber to transfer water from the second airflow to the
liquid desiccant during the first mode of operation; and exhausting
the second airflow from the second process chamber into an ambient
environment having air to be conditioned, after the second airflow
has contacted the liquid in the second process chamber.
20. The method of claim 19, further comprising inhibiting the first
airflow from contacting the liquid desiccant in the regeneration
chamber during a second mode of operation; and bringing a second
airflow into contact with the liquid desiccant in the second
process chamber to transfer water from the liquid desiccant to the
second airflow during the second mode of operation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
patent application No. 61/527,904 filed 26 Aug. 2011, which is
hereby incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a system and method of
desiccant-based air conditioning.
BACKGROUND
[0003] Air conditioning systems may utilize any of a variety of
processes for heating, cooling, dehumidifying, and humidifying air.
For example, a vapor-compression system may take advantage of the
expansion and compression of a refrigerant to provide cooling
and/or heat into different ambient spaces. Another type of air
conditioning system uses a hygroscopic material, such as a
desiccant, to remove or add water to an airstream, and to cool or
heat an ambient environment. Examples of such systems are described
in the following patent: U.S. Pat. No. 6,487,872, issued on 3 Dec.
2002, which is hereby incorporated herein by reference.
[0004] Typically desiccant-based systems employ a central unit that
uses a desiccant to remove moisture from one airstream, which
dilutes the desiccant, and to give up moisture from the desiccant
to another airstream, thereby concentrating or regenerating the
diluted desiccant. The central unit then provides the conditioned
air to an ambient environment, which may be, for example, one or
more rooms within a building.
[0005] One limitation of this type of desiccant system is that it
may not allow for individual control of the ambient environment
within different rooms in a building. Remotely locating different
portions of a desiccant system--for example, by having a
regenerator outdoors and a process portion indoors--can require a
complex system for balancing the concentration of the desiccant
between the regeneration and process activities. Thus, a need
exists for a desiccant-based air conditioning system that provides
individual control for one or more rooms in a building, without an
unduly complex system for desiccant balance.
SUMMARY
[0006] Embodiments of the present invention provide a system and
method for conditioning air using a desiccant-based system that
allows individual control of the environment in one or more rooms
in a building.
[0007] Embodiments of the invention include a system having a first
subsystem disposed outside a building whose environment is to be
controlled. A second subsystem is located inside the building, in a
room where it is desired to control the environment. The second
subsystem is connected to the first subsystem, such that desiccant
is transferred between the first and second subsystems as required
to provide the desired environment within the room.
[0008] Embodiments of the invention also include a desiccant-based
air conditioning system having a first subsystem, or outdoor unit,
and multiple second subsystems, or indoor units. Each of the indoor
units is connected to the outdoor unit, such that desiccant can
flow to and from each of the indoor units individually as required
to provide separate environmental control for each of the rooms.
One way this can be accomplished is by using a float-actuated valve
to control the flow of desiccant into the indoor units. A
temperature sensor can also be connected to the valve to provide
further control so that flow of desiccant into the indoor unit can
be a function of both mass and temperature of the desiccant. In
this way, a computer algorithm can be employed to control the flow
of desiccant into and out of the indoor units individually so that
different environmental conditions can be maintained in the
respective spaces where the indoor units are located.
[0009] For purposes of cooling and dehumidification, the indoor
units will receive cool, concentrated desiccant from the outdoor
unit, which is then brought into contact with an airflow from the
inside space. The airflow may enter one portion of the indoor unit,
where it gives up water to the desiccant and is simultaneously
cooled. The dry, cool air is then exhausted into the ambient
environment to provide the desired conditions.
[0010] The diluted desiccant may be gathered in a sump in the
indoor unit and transferred back to the outdoor unit, for example,
by gravity or a pump system. The diluted desiccant is regenerated
in the outdoor unit, where it can be exposed to a combination of
heat and a relatively dry airflow that removes water from the
desiccant. In some embodiments of the invention, the heat may be
provided through one or more heat exchangers that are part of a
vapor-compression system. The vapor-compression system also
includes at least one evaporator, and this can be the source of
cooling for the desiccant that is provided to the indoor units.
[0011] The outdoor unit itself may be divided into separate
chambers, a first of which, a first process chamber, receives the
diluted desiccant from the indoor units and transfers regenerated
desiccant to the indoor units. The second chamber in the outdoor
unit performs the regeneration of the diluted desiccant by adding
an airflow and/or heat to remove the water from the desiccant. The
two chambers may be connected, for example, through an orifice, or
some other mechanism effective to transfer the desiccant between
the chambers.
[0012] In addition to the foregoing, embodiments of the present
invention also provide a mechanism for humidifying and warming the
indoor air that is processed by the indoor units. This can be
accomplished, for example, by adding water to the desiccant in the
outdoor unit so that desiccant being transferred to the indoor
units contains a relatively high percentage of water. Thus, when
the indoor air is processed by one of the indoor units, it picks up
water from the desiccant and exhausts moist air back into the
indoor environment. This may be particularly helpful in the winter
in cold climates when the air is generally very dry. In this same
way, the desiccant in the outdoor unit can be heated so that in
addition to providing moisture to the indoor air, it warms the air
as it is processed through the indoor unit.
[0013] At least some embodiments of the invention include a system
for conditioning air. The system includes a first unit housing a
regenerator operable to receive a first airflow and bring the first
airflow into contact with a liquid desiccant to transfer water from
the liquid desiccant to the first airflow. The regenerator includes
a regenerator sump for collecting the liquid desiccant after water
is transferred to the liquid desiccant from the first airflow, the
first unit further housing a first portion of a process sump
fluidly connected to the regenerator sump. A second unit is
remotely located from the first unit and is configured to receive a
second airflow and bring the second airflow into contact with the
liquid desiccant. The second unit houses a second portion of the
process sump for collecting the liquid desiccant after it contacts
the second airflow. The first unit is in selective fluid
communication with the second unit such that the liquid desiccant
can be selectively transferred between the first and second
portions of the process sump, and the liquid desiccant transferred
from the second portion of the process sump to the first portion of
the process sump can be admixed with the liquid desiccant in the
regenerator sump prior to the liquid desiccant being returned to
the second unit.
[0014] At least some embodiments of the invention include a system
for conditioning air that includes a first unit remotely located
from an indoor space, and a second unit located within the indoor
space and in selective fluid communication with the first unit. The
first unit includes a regeneration chamber into which a first
airflow is introduced and contacted with a liquid desiccant to
transfer water from the liquid desiccant to the first airflow. The
regeneration chamber includes a regenerator sump for collecting the
liquid desiccant after water is transferred to the liquid desiccant
from the first airflow. The first unit further includes a first
process chamber separated from the regenerator chamber such that
the first airflow is inhibited from entering the first process
chamber. The first process chamber includes a first portion of a
process sump fluidly connected to the regenerator sump. The second
unit includes a second process chamber into which a second airflow
is introduced and contacted with the liquid desiccant to transfer
water between the second airflow and the liquid desiccant prior to
the second airflow being discharged into the indoor space. The
second process chamber includes a second portion of the process
sump for collecting the liquid desiccant after it contacts the
second airflow. The selective fluid communication between the first
and second units providing selective transfer of the liquid
desiccant between the first and second portions of the process
sump.
[0015] At least some embodiments of the invention include a method
for conditioning air that includes bringing a first airflow into
contact with a liquid desiccant in a regeneration chamber to
transfer water from the liquid desiccant to the first airflow
during a first mode of operation. The liquid desiccant is collected
in a regenerator sump after water is transferred from the liquid
desiccant to the first airflow. The liquid desiccant in the
regenerator sump is admixed with liquid desiccant in a first
portion of a process sump disposed in a first process chamber
adjacent the regeneration chamber. Some of the liquid desiccant
from the first portion of the process sump is transferred to a
second portion of the process sump disposed in a second process
chamber located remotely from the first process chamber. A second
airflow is brought into contact with the liquid desiccant in the
second process chamber to transfer water from the second airflow to
the liquid desiccant during the first mode of operation. The second
airflow is exhausted from the second process chamber into an
ambient environment having air to be conditioned, after the second
airflow has contacted the liquid in the second process chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic representation of an embodiment of the
present invention having an outdoor unit and three indoor units
located in separate rooms in a building;
[0017] FIG. 2 is a schematic representation of an outdoor unit in
accordance with an embodiment of the present invention shown as
operational in a first mode of operation;
[0018] FIGS. 3A and 3B respectively show front and side schematic
views of an indoor unit in accordance with an embodiment of the
present invention; and
[0019] FIG. 4 is a schematic representation of an outdoor unit in
accordance with an embodiment of the present invention shown as
operational in a second mode of operation.
DETAILED DESCRIPTION
[0020] As required, detailed embodiments of the present invention
are disclosed herein; however, it is to be understood that the
disclosed embodiments are merely exemplary of the invention that
may be embodied in various and alternative forms. The figures are
not necessarily to scale; some features may be exaggerated or
minimized to show details of particular components. Therefore,
specific structural and functional details disclosed herein are not
to be interpreted as limiting, but merely as a representative basis
for teaching one skilled in the art to variously employ the present
invention.
[0021] FIG. 1 shows a desiccant-based air conditioning system 10 in
accordance with an embodiment of the present invention. The system
10 includes a first unit, or outdoor unit 12, and three "second
units", or indoor units 14, 16, 18, remotely located from the
outdoor unit 12. Each of the indoor units 14, 16, 18 is located in
a respective room 20, 22, 24 within a building 26. Although at
least some of the indoor units 14, 16, 18 appear to be located a
relatively long distance from the outdoor unit 12, embodiments of
the invention may have first and second units remotely located from
each other, but still within a relatively close distance of each
other. In general, the term "remotely located" refers to the first
and second units being at least substantially located in and
working on different ambient environments--e.g., an outdoor and
indoor environment.
[0022] As shown in FIG. 1, a supply line 28 provides desiccant from
the outdoor unit 12 to each of the indoor units 14, 16, 18;
similarly, a return line 30 receives desiccant from each of the
indoor units 14, 16, 18 and returns it to the outdoor unit 12.
Although three indoor units are shown in FIG. 1, other embodiments
may include more or less than three indoor units. As used herein,
the words "indoor" and "building" generally refer to any structure
that defines an at least partially enclosed space and separates it
from an ambient outdoor environment. For example, a "building"
could be a tent or other temporary, partially enclosed
structure.
[0023] FIG. 2 shows a schematic representation of the outdoor unit
12 shown in FIG. 1. The outdoor unit 12 houses a first process
chamber 32 where desiccant 34 is transferred to and from the indoor
units 14, 16, 18. Any desiccant material effective to produce the
desired result may be used, including liquids in the form of pure
liquids, solutions, aqueous solutions, mixtures, and combinations
thereof. Lithium chloride (LiCl) and calcium chloride (CaCl.sub.2)
are typical of liquid desiccant solutions, but other liquid
desiccants may be employed. The outdoor unit 12 also houses a
regenerator 35, which includes a regeneration chamber 36 where the
desiccant 34 may be regenerated. In the embodiment shown in FIG. 2,
the desiccant 34 transfers between the first process chamber 32 and
the regeneration chamber 36 via an aperture, which may be an
orifice 38. In other embodiments, the transfer can be controlled
through a float and pump mechanism, or any other method or system
effective to transfer the desiccant as desired. More specifically,
the desiccant 34 transfers between a first portion of a process
sump 42 and a regenerator sump 43, which are separated by a divider
39 having the orifice 38 disposed therein, which allows diffusion
of the desiccant 34 between the sumps 42, 43 based on a
concentration gradient. As explained in more detail below, the
indoor units each include a second portion of the process sump,
each of which is in selective fluid communication with the first
portion of the process sump 42.
[0024] As shown in FIG. 2, the first chamber 32 receives desiccant
34 from the indoor units 14, 16, 18, as indicated by dashed line
40. In this embodiment, the desiccant 34 is held in the first
portion of the process sump 42 at the bottom of the first process
chamber 32 housed within outdoor unit 12. A first process pump 44
is used to pump the desiccant 34 from the first portion of the
process sump 42 through a heat exchanger 46 and then to the indoor
units, as indicated by the dashed line 48. In the embodiment shown
in FIG. 2, the heat exchanger 46 is an evaporator that is part of a
refrigeration system, based on a vapor-compression cycle, including
a compressor 50, a first condenser 52, a second condenser 54, and a
thermal expansion valve 55. In other embodiments, a desiccant may
be cooled and heated by other sources, such as a cold water
reservoir, solar heat, etc. A bypass valve 57 allows some of the
cooled desiccant 34 to be reintroduced into the first process
chamber 32, as indicated by the dashed line 59. The addition of the
cooled desiccant 34 back into the first portion of the process sump
42 effectively allows the sump 42 to retain cooled desiccant 34 and
act as a cold liquid storage which can be drawn from when one or
more of the indoor units 14, 16, 18 calls for cooling.
[0025] The vapor-compression system shown in FIG. 2 may use any
fluid, such as a refrigerant, effective to allow the
vapor-compression system to selectively heat and cool the desiccant
34 through heat transfer to and from the refrigerant. FIG. 2 shows
the outdoor unit 12 in a first mode of operation, which may be used
effectively in warm, humid conditions. In this mode, heat from the
first condenser 52 is transferred to the desiccant 34 as indicated
by the dashed line 56. The desiccant 34 is pumped through the
condenser 52 by a regenerator pump 58. After leaving the condenser
52, the desiccant 34 is sprayed over media 60, which may include
one or more porous materials that allow the desiccant 34 to flow
through them. The second condenser 54 may have associated with it a
fan (not shown) for transferring some of the heat from the
vapor-compression system into an ambient environment outside of the
outdoor unit 12, thereby further cooling the refrigerant prior to
the expansion phase of the cycle. Although the compressor 50 and
condenser 52 are shown within the regeneration chamber 36, in other
embodiments, they may be located outside of a regeneration chamber
and either inside another portion of a first unit, or outside of
the first unit entirely. Having these components within the
regeneration chamber 36 provides additional heat to the
regeneration process, thereby helping to evaporate even more water
from the desiccant 34.
[0026] As noted above, the desiccant 34 receives heat from the heat
exchanger 52, and this process helps to regenerate the desiccant 34
by driving off some of the water that has been picked up by the
indoor units 14, 16, 18 from the air in their respective indoor
spaces 20, 22, 24. In addition to using heat to drive off some of
the moisture from the desiccant 34, the outdoor unit 12 also uses
an airflow to further remove moisture. As shown in FIG. 2, a first
airflow 62 from an ambient outdoor environment enters the second
chamber 36 through an intake 64. The airflow 62 is drawn in by a
fan 66, which moves the air into the second chamber 36, across the
desiccant-laden media 60, and out through an exhaust port 68, where
the airflow 62 is now shown as 62', indicating that it is now
moisture-laden as it leaves the second chamber 36. Because the
orifice 38 is located below the level of the desiccant in the sumps
42, 43, the first process chamber 32 is effectively sealed from any
contact with the airflow 62.
[0027] FIGS. 3A and 3B respectively show front and side views of
one of the indoor units 14 shown in FIG. 1. As shown in FIG. 3A, a
valve 70 receives desiccant 34 from the outdoor unit 12 as shown by
dashed line 72, and in particular, it receives the desiccant 34
from the first portion of the process sump 42. The valve 70 is
connected to a float system 74, which indicates the level of the
desiccant 34 in a second portion of the process sump 76 at the
bottom of a second process chamber 77 housed within the indoor unit
14. Thus, in the embodiment illustrated and described herein, the
process side of the system 10 is a split between the outdoor unit
12 and the indoor units 14, 16, 18. Having a portion of the process
side located within the same unit that houses the regeneration
portion of the system 10 significantly reduces the complexity of
mass and energy transfer related to balancing the desiccant 34
between the dilute process side desiccant and the more concentrated
regenerator side desiccant. Moreover, having another portion of the
process side housed within the indoor units allows for individual
control over conditioning of the ambient air in different
spaces.
[0028] In addition to receiving information regarding the level of
the desiccant 34, the valve 70 also receives information from a
temperature sensor 78, which measures the temperature of the
desiccant 34 in the sump 76. The valve 70 may be, for example, a
three-way electronically actuated solenoid valve, which responds to
certain inputs, including inputs from the float system 74 and the
temperature sensor 78. Control of the valve 70 may be part of a
larger control system that also coordinates and controls the
operation of the various components of the outdoor unit shown in
FIG. 2. Such a control system may contain one or more algorithms
that allow each of the indoor units 14, 16, 18 to be operated
independently of each other to provide for independent control of
the environment in their respective rooms 20, 22, 24.
[0029] When the inputs to the valve 70, such as the level of the
desiccant 34 indicated by the float system 74 and/or the
temperature of the desiccant 34 as indicated by the temperature
sensor 78, indicate that the valve 70 should be opened, desiccant
from the outdoor unit 12 is provided to the indoor unit 14, as
shown by the dashed line 80. In warm, humid environments, the
desiccant 34 entering the indoor unit 14 from the outdoor unit 12
will be cool and relatively dry--i.e., undiluted by water. As
explained below, this allows the ambient air in the room 20 to be
dehumidified and cooled to a desired level.
[0030] FIG. 3B shows the indoor unit 14 from a side view, and
indicates how air flows through and is processed by the unit 14.
First, a second airflow 86 from an ambient indoor environment
enters the indoor unit 14; once inside, the airflow 86 is brought
into contact with the desiccant 34 as it passes over media 84, as
indicated by the arrow 88. The flow of air is controlled by a fan
90, which exhausts the second airflow 86 back into the ambient
environment after it has been cooled and dehumidified, now
indicated by the label 86'. As the desiccant 34 in the indoor unit
14 continues to collect water, the level of the desiccant 34 in the
sump 76 will rise. In addition, the temperature of the desiccant 34
in the second portion of the process sump 76 will increase.
[0031] At some point, some of the desiccant 34 will be pumped back
into the outdoor unit as indicated by the dashed line 94 shown in
FIG. 3A. The desiccant 34 in the indoor unit 14 may flow to the
outdoor unit via a gravity feed, or it may be pumped. Thus, the
apparatus 96 illustrated schematically in FIG. 3A may be, for
example, a valve that allows the desiccant 34 to automatically flow
out of the indoor unit 14 when it reaches a certain level.
Alternatively, the apparatus 96 may be an electronically actuated
valve, such as the valve 70 described above. In such a case, the
valve 96 may be opened upon the occurrence of certain input
signals, such as the temperature and/or level of the desiccant 34
in the sump 76. Upon returning to the outdoor unit 12, the
desiccant 34 is regenerated in accordance with the procedures
described above.
[0032] Because the indoor units 14, 16, 18 are separately
controlled and serve spaces that may have different requirements,
the float system 74 may be actuated frequently in some units, while
in other units it is actuated very infrequently. In at least some
situations, the airflow 86, 86' may recirculate many times through
a particular indoor unit before the float system 74 is actuated.
This is another advantage of having the process side of a
desiccant-based air conditioning system split between the outdoor
unit and the individual indoor units--i.e., transfer of desiccant
from the indoor units does not need to be based on the
concentration of the desiccant in the indoor unit sump (although it
can be); rather, it can be based on a temperature or strictly on a
volume of liquid in the indoor sump. In this way, the more complex
control of balancing the concentration of the desiccant is handled
entirely in the outdoor unit, independent of the indoor units.
[0033] The air conditioning described above operates in a first
mode of operation to cool and dehumidify ambient air inside a room.
The system 10 can, however, also condition air to have an opposite
effect--i.e., the system 10 can be operated in a second mode of
operation to warm and increase the humidity of ambient air within a
space. One way that this can be accomplished is to provide
additional water directly to the outdoor unit 12. This is
illustrated in FIG. 4, by the dashed line 98, which shows the
addition of water directly to the first portion of the process
sump, labeled in FIG. 4 as 42', with the prime symbol (')
indicating like components from the other drawing figures, which
showed components of the system 10 in a first mode of operation.
The regenerator 35' is shut down, and in particular the pump 58'
and fan 66' are not operated, so the addition of the water to the
outdoor unit 12 directly results in an increased dilution of the
desiccant 34 in the sump 42', and water is not evaporated from the
desiccant in the regenerator sump 43'.
[0034] In addition to adding water to the desiccant 34, it is also
possible to add heat to the desiccant 34 so that a warm, dilute
desiccant can be provided to the indoor units 14, 16, 18. Heat can
be added by any method effective to achieve the desired result,
such as operating the vapor-compression system in reverse. As shown
in FIG. 4, the compressor 50' now pumps refrigerant to the first
condenser 52', which is used to exchange heat with the desiccant 34
being pumped by the first process pump 44' from the first portion
of the process sump 42' to the indoor units 14, 16, 18. In this
second mode of operation, which may be considered in some cases a
"winter mode", the refrigerant can optionally be pumped through a
second condenser 54', and although not shown in FIG. 4, the
desiccant 34 can be pumped through both condensers 52', 54' to pick
up additional heat.
[0035] Alternatively, the system 10 can be provided with solar
collectors that are either physically attached or remotely operated
to provide heat and/or electricity to the system 10. When this
process is followed, the warm, dilute desiccant 34 is passed over
the media 84--see FIG. 3A--where moisture and heat are collected by
the second airflow 86--see FIG. 3B--prior to its being exhausted
back into the ambient environment.
[0036] While exemplary embodiments are described above, it is not
intended that these embodiments describe all possible forms of the
invention. Rather, the words used in the specification are words of
description rather than limitation, and it is understood that
various changes may be made without departing from the spirit and
scope of the invention. Additionally, the features of various
implementing embodiments may be combined to form further
embodiments of the invention.
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