Note: Descriptions are shown in the official language in which they were submitted.
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WATER RECOVERY IN DESICCANT ENHANCED EVAPORATIVE COOLING SYSTEMS
BACKGROUND
[0001] There are many applications for which controlling the environmental
conditions
within an enclosed space is important - for example, cooling data centers. A
data center usually
consists of computers and associated components operating 24 hours a day, 7
days a week. The
electrical components in data centers produce a lot of heat, which needs to be
removed from the
space. Air-conditioning systems in data centers can consume as much as 40% of
the total energ
[0002] Comfort cooling of residential, commercial and institutional
buildings is
predominantly done using vapor-compression cooling equipment. Many process
applications,
such as data centers, also use mechanical cooling for primary or supplemental
cooling. In most
of these applications, the required cooling temperature is moderate (for
example, 50 F - 85 F;
C - 30 C). Mechanical cooling equipment can produce high cooling capacities,
operate
reliably and can have acceptable cost due to mass production of compressors,
exchangers and
other components. However, these systems require significant amounts of high
grade electrical
energy to operate. For example, about 15% of the total annual US domestic
electricity
production is consumed by air conditioning units. Moreover, about one-third of
the peak
demand in hot summer months is driven by air conditioning units, leading to
issues with power
grid loading and stability. The production of electricity remains carbon
intensive, so electricity
driven cooling systems can contribute significantly to emissions and global
warming.
[0003] Thermoelectric power production requires vast amounts of water for
cooling, and
the US average water consumption (evaporated water) for combined
thermoelectric and
hydroelectric power production is about 2 gallons/kWh. The water consumed to
produce the
electricity required by an EER 11 air conditioner is about equivalent to the
water consumed by
an evaporative cooling system producing an equivalent amount of cooling.
However,
evaporative cooling systems consume far less electricity. Vapor-compression
also typically
requires synthetic refrigerants operating at high pressures. The deployment of
large quantities
of refrigerants in air conditioning and refrigeration systems has resulted in
safety, health and
environmental concerns. Modern high efficiency refrigerants, such as HFCs, can
have high
global warming potential and are being phased out There is currently no direct
replacement
refrigerant option that has all the desired properties in terms of efficiency,
stability,
flammability, toxicity, and environmental impact.
[0004] Evaporative cooling systems are used successfully in many
applications, especially
in dry climates. Direct evaporative coolers (DEC) can be simple in design and
efficient,
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compared to, for example, vapor compression systems. However, conventional
DECs can have
some drawbacks. The supply air temperature coming out of the cooler may be
challenging to
control and is dependent on the outdoor air temperature and humidity level.
The supply air may
be excessively humid. These systems need careful maintenance to ensure that
bacteria, algae,
fungi and other contaminants do not proliferate in the water system and
transfer into the
supply air stream. Since these systems utilize direct contact between the
evaporating liquid
water and supply air, carryover of contaminants into the air stream can occur,
which can, in
turn, lead to reduced indoor air quality, odors and "sick building syndrome."
Also, buildup of
mineral deposits in the unit and on the evaporative pads can reduce
performance and require
maintenance.
[0005] Indirect evaporative coolers address the humidity problem but
typically operate at
lower wet bulb efficiencies. State-of-the-art dew-point evaporative coolers
can deliver lower
cooling temperatures than conventional direct or indirect evaporative systems
and can
maintain cooling power to higher outdoor wet bulb temperatures. However, all
evaporative
cooling technologies lose cooling performance as the working air humidity
rises and cannot be
used in humid climates without supplemental (usually vapor compression)
cooling equipment.
The water usage efficiency of evaporative cooling systems also varies widely
depending on the
system design and control characteristics. The water usage of evaporative
coolers can be a
problem, or at least a perceived problem. For example, large scale data
centers may consume
large quantities of potable water. Moreover, for those locations in which
evaporative cooling
works best (dry climates), the water demand may not be sustainable.
[0006] There remains a need for alternative cooling technologies for
comfort conditioning
applications, which can largely replace mechanical cooling. The growing
awareness of
environmental impacts, including water consumption, are pressing challenges
for current HVAC
cooling equipment
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] In the drawings, which are not necessarily drawn to scale, like
numerals may
describe similar components in different views. Like numerals having different
letter suffixes
may represent different instances of similar components, sub-components of a
larger logical or
physical system, or the like. The drawings illustrate generally, by way of
example, but not by
way of limitation, various examples described in the present disclosure.
[0008] FIG. 1 schematically depicts an example regeneration system for use
in a
conditioning system with a desiccant dryer LAMEE and an evaporative cooler.
[0009] FIG. 2 schematically depicts another example conditioning system
including a
regeneration system having a heat recovery exchanger (HRE).
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[0010] FIG. 3 schematically depicts a portion of the regeneration system of
FIG. 2.
[0011] FIG. 4 schematically depicts another example conditioning system
including a
regeneration system.
[0012] FIG. 5 schematically depicts another example conditioning system
including a
centralized regeneration system.
[0013] FIG. 6 schematically depicts another example regeneration system for
use in a
conditioning system.
[0014] FIG. 7 is a flowchart depicting a method of operating a conditioning
system in
accordance with this disclosure.
OVERVIEW
[0015] The inventor(s) recognize, among other things, an opportunity for
improved
performance in providing cooling to an enclosed space through design of a
conditioning system
using a first Liquid-to-Air Membrane Energy Exchanger (LAMEE) as a
dehumidifier to dry the
air in an air stream passing through the first LAMEE, thus lowering the
enthalpy and dew point
of the air, and then passing the air through a second LAMEE (or another type
of evaporative
cooler). In an example, the second LAMEE can be used to condition the air
stream so that the
conditioned air can be provided to the enclosed space. In another example, the
second LAMEE
can be used to cool a water stream flowing through the LAMEE such that the
water stream can
be delivered to a second plenum for cooling a process air stream. The
inventor(s) also
recognize an opportunity to use the water removed from the process air stream
by the first
LAMEE as a source of water supply for evaporative coolers in the system,
including, for example,
the second LAMEE (or other evaporative cooler) downstream, to reduce or
eliminate the need
for an external water supply.
[0016] Examples according to the present application can include a system
for conditioning
air for an enclosed space and the system can include a LAMEE, arranged inside
a plenum
configured to direct an air flow path from an inlet to an outlet, and a
regeneration system in
fluid connection with the LAMEE. The system can also include one or more
cooling components
arranged inside the plenum. The LAMEE can comprise a desiccant flow path
separated from an
air flow path by a membrane and the desiccant can remove water from the air in
the air flow
path. The regeneration system can be configured to separate a portion of the
water from the
desiccant such that the regeneration system can output a concentrated
desiccant stream and a
distilled water stream. The concentrated desiccant stream can be returned for
recirculation
through the LAMEE. In an example, only a portion of the dilute desiccant from
the LAMEE is
regenerated. The one or more cooling components can utilize at least a portion
of the distilled
water stream recovered in regeneration for use as make up water. This can
reduce or eliminate
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an external water supply for the conditioning system. In an example, the one
or more cooling
components can include an evaporative cooler arranged inside the plenum
downstream of the
dryer LAMEE. In an example, the downstream evaporative cooler can be a second
LAMEE.
[0017] The dryer LAMEEs disclosed herein are designed such that the
desiccant can remove
at least one of moisture and heat from the air stream. Essentially all of the
energy removed
from the air stream can be transferred to the desiccant. The LAMEE can thus be
a two-fluid
design with the first fluid being the air and the second fluid being the
desiccant.
[0018] In an example, the conditioning system can include a liquid to
liquid heat exchanger
(LLHX) or a liquid to air heat exchanger (LAHX) configured to cool the
desiccant prior to
circulating the desiccant through the LAMEE. In an example, the LAHX or LLHX
can be
configured outside of the plenum. In an example, the LAHX can include
evaporative cooling
capabilities and can use water from the regenerator as make up water. In an
example, the LAHX
can use outdoor air to cool the desiccant
[0019] In an example, the regeneration system can include a thermally
driven regeneration
unit. In an example, the regeneration system can use non-thermal sources of
energy to separate
the water and the desiccant in the desiccant stream.
[0020] In an example, the conditioning system can include a single plenum
and a single
working air stream. The air stream can be hot process air from the enclosed
space and the air
can be conditioned inside the plenum such that the process air can be returned
to the enclosed
space at a reduced temperature or humidity. The air stream can be outdoor air
that can be
conditioned such that it can be delivered to the enclosed space at a reduced
temperature or
humidity. The air stream can be a combination of outdoor air and process air.
[0021] In an example, the conditioning system can include two plenums and
two working
air streams. A first plenum can receive a scavenger air stream and direct the
scavenger air
through a dryer LAMEE and an evaporative cooler downstream of the dryer LAMEE.
The
evaporative cooler can produce reduced-temperature water for cooling. The
second plenum
can receive a process air stream from the enclosed space and direct the
process air through an
LAHX in the second plenum, using the reduced-temperature water from the first
plenum to cool
the process air. The process air can then be returned to the enclosed space.
[0022] Examples according to the present application can include a system
for conditioning
air for an enclosed space and the system can include a desiccant dryer LAMEE
arranged inside a
plenum, the desiccant dryer LAMEE configured for air to pass there through and
use a desiccant
flowing there through to remove water from the air. The desiccant and air can
be separated in
the LAMEE by a membrane and the LAMEE can facilitate an energy exchange
between the air
and the desiccant such that the desiccant collects essentially all of the
energy removed from the
air. The conditioning system can also include an evaporative cooler arranged
inside the plenum
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downstream of the desiccant dryer LAMEE and configured to cool at least one of
the air and
water circulating through the evaporative cooler. The conditioning system can
also include a
fluid circuit coupled to the desiccant dryer LAMEE and the evaporative cooler,
and including a
regenerator configured to separate water and desiccant in a desiccant stream.
The fluid circuit
is configured to transport at least a portion of the water removed from the
air by the desiccant
dryer LAMEE and separated in the regenerator to the evaporative cooler for use
as make up
water for operation of the evaporative cooler. In an example, the regenerator
comprises a
thermal separation unit In an example, the regenerator comprises one or more
heat sources to
heat the desiccant prior to passing the desiccant into the thermal separation
unit. In an
example, the regenerator comprises a separation unit that is driven by a non-
thermal energy
source.
[0023] Examples according to the present application can include a method
of conditioning
air for an enclosed space and the method can include directing air through a
process plenum,
directing the air through a LAMEE inside the plenum and directing a desiccant
through the
LAMEE, the desiccant and air separated by a membrane of the LAMEE. The method
can include
transferring energy in the LAMEE from the desiccant to the air, an energy
reduction of the air
between a LAMEE inlet and outlet being about equal to an energy gain of the
desiccant between
the LAMEE inlet and outlet. The energy transfer includes removing water from
the air using the
desiccant such that a first concentration of water in the desiccant is lower
at a LAMEE inlet
compared to a second concentration of water in the desiccant at a LAMEE outlet
The method
can include regenerating a portion of the dilute desiccant in a regenerator to
separate the water
from the desiccant, directing a concentrated desiccant exiting the regenerator
to a fluid circuit
for the desiccant dryer LAMEE, and directing distilled water from the
regenerator to one or
more evaporative coolers in the conditioning system. The method can include
regulating the
portion of the dilute desiccant (from the dryer LAMEE) that is regenerated.
The one or more
evaporative coolers in the conditioning system can include an evaporative
cooler arranged
downstream of the dryer LAMEE and configured to cool the air passing through
the plenum. In
an example, the downstream evaporative cooler can be a second LAMEE.
[0024] The methods disclosed herein can markedly reduce or eliminate an
external water
supply for operation of the conditioning system. In an example, the enclosed
space can be a data
center. In an example, the conditioning systems disclosed herein can be used
in residential and
commercial applications.
[0025] Examples according to the present application can include a system
for conditioning
air for an enclosed space and the system can comprise a plurality of
conditioning units. Each
conditioning unit can include a plenum having a LAMEE and an evaporative
cooler downstream
of the LAMEE. The system can comprise a regeneration system in fluid
connection with the
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LAMEE outlet of each conditioning unit such that the regeneration system can
regenerate at
least a portion of the dilute desiccant from the outlet of the LAMEE of each
unit. The system can
comprise a concentrated desiccant storage system to receive and store the
concentrated
desiccant from the regenerator system and a distilled water storage system to
receive and store
the distilled water from the regenerator system. Concentrated desiccant can be
supplied to
each conditioning unit as needed for operation of the LAMEE of each
conditioning unit Distilled
water can be supplied to an evaporative cooler of each unit as needed for
operation of the
evaporative cooling component. The system can markedly reduce or eliminate an
external
water supply for operation of multiple conditioning units.
[0026] This overview is intended to provide an overview of subject matter
of the present
patent application. It is not intended to provide an exclusive or exhaustive
explanation of the
invention. The detailed description is included to provide further information
about the present
patent application.
DETAILED DESCRIPTION
[0027] The present application relates to systems and methods for
conditioning air for an
enclosed space, and includes using a liquid to air membrane energy exchanger
(LAMEE) as a
desiccant dryer in combination with a regeneration system to collect water
from an air stream
for use as make up water for one or more evaporative coolers in the
conditioning system. This
can reduce or eliminate an external water supply for operation of the
conditioning system and
markedly improve the water usage efficiency as compared to existing designs of
evaporative
coolers. The desiccant dryer LAMEE can circulate a liquid desiccant, such as
for example,
lithium chloride, to remove moisture from the air stream passing through the
LAMEE. The
liquid desiccant and the LAMEE are described in further detail below. In an
example, the
conditioning system can include an evaporative cooler (arranged in a plenum
downstream of
the desiccant dryer LAM EE and the evaporative cooler can be configured to
provide cooling to
the air stream passing through the plenum or to a water stream passing through
the
evaporative cooler. The evaporative cooler can use the water from the air
stream, recovered in
regeneration, as the make up water for the evaporative cooler. In an example,
the evaporative
cooler can be a LAMEE, operating as an evaporative cooler. In such an example,
the desiccant
dryer LAMEE is a first LAMEE and the evaporative cooler LAMEE is a second
LAMEE.
[0028] In an example, the conditioning system can include a liquid to air
heat exchanger
(LAHX), such as a cooling coil, arranged between the desiccant dryer LAMEE and
the
evaporative cooler, and configured to pre-cool the air stream prior to passing
the air stream
through the evaporative cooler. In an example, the LAHX/pre-cooler can use the
water from the
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air stream, recovered in regeneration, as the cooling fluid for circulation
through the LAHX/pre-
cooler.
[0029] The desiccant exiting the LAM EE can be a dilute desiccant stream.
The conditioning
system can operate effectively with only a portion of the dilute desiccant
going through the
regeneration system. In an example, a desiccant storage tank can be used to
mix the dilute
desiccant (exiting the LAMEE) with a concentrated desiccant stream from the
regeneration
system.
[0030] In an example, the conditioning system can be configured to
condition hot process
air (return air) from an enclosed space and return the process air to the
enclosed space as cold,
or reduced temperature process air (supply air). In another example, the
conditioning system
can condition outdoor air and deliver the conditioned air to an enclosed
space. In yet another
example, the conditioning system can condition a combination of process air
and outdoor (make
up) air for delivery to an enclosed space.
[0031] A liquid to air membrane energy exchanger (LAMEE) can be used as
part of a
conditioning system to transfer heat and moisture between a liquid and an air
stream, both
flowing through the LAMEE, in order to condition the temperature and humidity
of the air or to
reduce a temperature of the liquid. In an example, the membrane in the LAMEE
can be a non-
porous film having selective permeability for water, but not for other
constituents that may be
present in the liquid. Many different types of liquids can be used in
combination with the non-
porous membrane, including, for example, water, liquid desiccants, glycols. In
an example, the
membrane in the LAMEE can be semi-permeable or vapor permeable, and generally
anything in
a gas phase can pass through the membrane and generally anything in a liquid
phase cannot
pass through the membrane. In an example, the membrane in the LAM EE can be
micro-porous
such that one or more gases can pass through the membrane. In an example, the
membrane can
be a selectively-permeable membrane such that some constituents, but not
others, can pass
through the membrane. It is recognized that the LAMEEs included in the
conditioning systems
disclosed herein can use any type of membrane suitable for use with an
evaporative cooler
LAMEE or a desiccant dryer LAMEE.
[0032] In an example, the LAM EE can use a flexible polymer membrane, which
is vapor
permeable, to separate air and water. Relative to other systems/devices, the
water flow rate
and air flow rate through the LAMEE may not be limited by concerns such as
droplet carryover
at high face velocities. In addition, the LAMEE can operate with water flow
rates that enable the
transport of thermal energy into the cooler similar to a cooling tower, and
the elevated inlet
water temperatures can boost the evaporative cooling power of the LAMEE.
[0033] The desiccant dryer LAMEE can circulate any type of liquid desiccant
suitable for
removing moisture from the air. In an example, the cooling fluid is a liquid
desiccant that is a
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high concentration salt solution. The presence of salt can sanitize the
cooling fluid to prevent
microbial growth. In addition, the desiccant salt can affect the vapor
pressure of the solution
and allow the cooling fluid to either release or absorb moisture from the air.
Examples of salt-
based desiccants usable herein include lithium chloride, magnesium chloride,
calcium chloride,
lithium bromide, lithium iodide, potassium fluoride, zinc bromide, zinc
iodide, calcium bromide,
sodium iodide and sodium bromide. In an example, the liquid desiccant can
include an acetate
salt, such as, but not limited to, an aqueous potassium acetate and an aqueous
sodium acetate.
[0034] In an example, the liquid desiccant can include a glycol or glycol-
water solution.
Glycols can be unsuitable for use in a direct contact exchanger because the
glycol can evaporate
into the air stream. A glycol based liquid desiccant can be used here with a
non-porous
membrane since the membrane can prevent the transfer of the glycol into the
air. In an
example, the liquid desiccant can include glycols, or glycol-based solutions,
such as triethylene
glycol and propylene glycol, which are non-toxic, compatible with most metals
and
comparatively low in cost. Glycols can be strongly hygroscopic at higher
concentrations. For
example, a 95% solution of triethylene glycol has a comparable
drying/dehumidification
potential to lithium chloride near saturation. Triethylene glycol and
tripropylene glycol can
have low vapor pressures, but can be expensive. Less expensive and higher
vapor pressure
glycols, such as ethylene glycol, diethylene glycol, propylene glycol and
dipropylene glycol, can
be used herein.
[0035] Other examples of liquid desiccants usable in the desiccant dryer
LAMEE described
herein include, but are not limited to, hygroscopic polyol based solutions,
sulfuric acid and
phosphoric acid. Glycerol is an example of a hygroscopic polyol usable herein.
It is recognized
that mixtures of desiccants can be used as the liquid desiccant in the
desiccant dryer LAMEEs
described herein. In addition to the desiccants listed above, the liquid
desiccant can include,
but is not limited to, an acetate salt solution, a halide salt solution, a
hygroscopic polyol based
solution, a glycol based solution, a sulfuric acid solution, a phosphoric acid
solution, and any
combinations thereof
[0036] In an example, the conditioning system can include a regeneration
system
configured to increase a concentration of the liquid desiccant exiting the
desiccant dryer
LAMEE, prior to recirculating the liquid desiccant through the desiccant dryer
LAMEE. The
present application discloses systems and methods for recovering the water
from the air stream
(which is absorbed by the liquid desiccant in the desiccant dryer LAMEE) and
using the
recovered water as make up water for one or more cooling devices in the
system, including, for
example, the evaporative cooler located downstream of the desiccant dryer
LAMEE. The
systems and methods disclosed herein can eliminate or markedly reduce an
external water
consumption of the evaporative cooler
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[0037] In an example, a LAMEE can circulate an evaporative cooling fluid
through the
LAMEE and the LAMEE can operate as an evaporative cooler, using the cooling
potential in both
air and the cooling fluid (for example, water) to reject heat As described
above, the evaporative
cooler located downstream of the desiccant dryer LAMEE can be an evaporative
cooler LAMEE.
In an example in which the LAMEE is an evaporative cooler, as air flows
through the LAMEE,
water, or both the air and the water, can be cooled to temperatures
approaching the inlet air
wet bulb (VVB) temperature. Due to the evaporative cooling process in the
LAMEE, a
temperature of the water at the outlet of the LAMEE can be less than a
temperature of the water
at the inlet, or the temperature of the water may not be changed, but the air
may be cooled.
Other types of evaporative cooling fluids, including those listed above, can
be used in
combination with water or as an alternative to water.
[0038] A LAMEE can offer advantages over conventional cooling systems, such
as cooling
towers, for example. The membrane separation layer in the LAMEE can reduce
maintenance,
can eliminate the requirement for chemical treatments, and can reduce the
potential for
contaminant transfer to the liquid loop. The use of LAMEEs along with an
upstream and/or
downstream cooling coil (or other LAHX) can result in a lower temperature of
the water leaving
the LAMEE and a higher cooling potential. Various configurations of
conditioning systems
having one or more LAMEEs are described herein and can boost performance in
many climates.
[0039] FIG. 1 depicts an example regeneration system 11, which can be part
of a
conditioning system 10 to condition air for delivery to an enclosed space. The
conditioning
system 10 can be used in commercial and industrial applications, as well as
residential
applications. The conditioning system 10 can be used for cooling air that is
hot because of
surrounding equipment and conditions in the enclosed space. The conditioning
system 10 can
be used for comfort cooling in residential and commercial applications. The
conditioning
system 10 can receive hot process air from the enclosed space and condition
the process air
such that it can be returned to the enclosed space as reduced-temperature or
reduced-humidity
supply air. The conditioning system 10 can receive outdoor air and condition
the outdoor air
prior to delivering the outdoor air to the enclosed space. In other examples,
the conditioning
system 10 can receive a mix or combination of outdoor air and process air.
[0040] In an example in which the conditioning system 10 receives process
air from the
enclosed space, the conditioning system 10 can sometimes be referred to as a
100%
recirculation system, which generally means that the air within the enclosed
space recirculates
through the conditioning system 10 in a continuous cycle of being cooled by
the system 10 to a
target supply air temperature, supplied to the space, heated by elements in
the space (for
example, computers, servers, and other electronics), and returned to the
system 10 for cooling.
Although not shown or described in detail, in such an example, the
conditioning system 10 can
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include a make-up air unit or system, to continuously or periodically refresh
the air within the
space to satisfy ventilation requirements.
[0041] The conditioning system 10 can include a desiccant dryer LAMEE 6
arranged in a
plenum 4 and an evaporative cooler (EC) 8 arranged in the plenum 4 downstream
of the LAM EE
6. The plenum 4 can be configured to receive an air stream through a plenum
inlet 12 and
release the air stream through a plenum outlet 14. Associated and generally
collocated with the
inlet 12 and outlet 14 can be dampers 18 and 20, respectively. Although not
shown in FIG. 1, a
fan can be arranged inside the plenum 4 upstream of the desiccant dryer LAMEE
6 or in some
other location. In an example, the conditioning system 10 can be configured to
receive a
scavenger air stream if the system 10 has two working air streams (and two
plenums) or to
receive a return air stream (from an enclosed space) if the system 10 has one
working air
stream (and one process plenum). In another example, the air entering the
process plenum 4
can be outdoor air. In yet another example, the air entering the process
plenum 4 can be a
mixture of outdoor air and process air from the enclosed space.
[0042] The regeneration system 11 can be configured for use with a variety
of conditioning
systems that include a desiccant dryer LAMEE 6 in combination with an
evaporative cooler 8
downstream of the dryer LAMEE 6; such conditioning systems can include
additional
components not shown in FIG. 1. The conditioning system 10 can include one or
more features,
such as dampers, that can facilitate bypass of the desiccant dryer LAM EE 6.
[0043] The evaporative cooler 8 can be any type of evaporative cooler
suitable for use
inside the process plenum 4 for cooling an air stream or cooling an
evaporative fluid circulating
through the evaporative cooler 8 such that the fluid can be used to condition
a separate air
stream in a second plenum. In an example, the evaporative cooler 8 can be a
LAMEE, also
referred to herein as an evaporative cooler LAMEE. The evaporative cooler
LAMEE is a non-
contact evaporative cooler because the membrane in the LAM EE separates (and
maintains
separation between) the evaporative fluid (water) and the air. In such an
example in which the
evaporative cooler 8 is a LAMEE, the desiccant dryer LAMEE 6 can also be
referred to herein as
a first LAMEE 6 and the evaporative cooler LAMEE 8 can also be referred to
herein as a second
LAMEE 8. In other examples, the evaporative cooler 8 can include, but is not
limited to, a wetted
media or spray atomizer system, both of which are examples of direct-contact
evaporative
coolers since the evaporative fluid (water) directly contacts the air to cool
the air. In another
example, the evaporative cooler 8 can include a wet deck or other flooded fill
material (similar
to what can be used in a cooling tower) - these are additional examples of
direct-contact coolers
since the evaporative fluid directly contacts the air.
[0044] The conditioning system 10 can circulate a liquid desiccant through
the LAMEE 6 to
reduce a humidity level of the air stream entering the plenum 4, prior to
passing the air stream
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through the evaporative cooler 8. After circulating through the LAMEE 6, the
liquid desiccant
can be diluted due to absorbed moisture from the air. A reduction in the
concentration of the
desiccant can thereby reduce the drying ability of the LAMEE 6. The
regeneration system 11,
which can include a regenerator 52, can be configured to regenerate the liquid
desiccant prior
to recirculating the liquid desiccant back through the LAMEE 6.
[0045] After the liquid desiccant exits the LAMEE 6 at a LAMEE outlet 28,
the liquid
desiccant can be discharged into a desiccant tank 26 configured for storage of
the liquid
desiccant. The desiccant can be transported from the desiccant tank 26, via a
pump 42, to the
regenerator 52 and a liquid to air heat exchanger (LAHX) or a liquid to liquid
heat exchanger
(LLHX) 32. The LAHX or LLHX 32 can be configured to reduce a temperature of
the desiccant
prior to passing the desiccant into the LAMEE 6 at a LAMEE inlet 34. The LAHX
or LLHX 32 and
the regenerator 52, in combination, can thus decrease a temperature and
increase a
concentration of the liquid desiccant prior to circulating the desiccant
through the LAMEE 6.
Both capabilities can be important in order for the desiccant to effectively
remove moisture
from the air stream passing through the LAMEE 6. A modulating valve 68 can
control and vary a
distribution of the desiccant from the tank 26 to the regenerator 52 and the
LAHX or LLHX 32,
as described further below.
[0046] The regeneration system 11 can include a portion of a first
desiccant circuit 24 and a
second desiccant circuit 66 in fluid connection with the first desiccant
circuit 24. The LAHX or
LLHX 32 can be part of the first desiccant circuit 24. The tank 26 can be part
of the first
desiccant circuit 24 and the second desiccant circuit 66. The regenerator 52
can be part of the
second desiccant circuit 66. The regenerator 52 can include an energy input to
facilitate
separation of the water and desiccant. For example, such energy input can
include, but is not
limited to, heat, mechanical power, electrical power, or a combination thereof
[0047] The desiccant exiting the tank 26 can be transported to the
regenerator 52 via the
second desiccant circuit 66 and enter the regenerator 52 at an inlet 70. The
regenerator 52 can
separate a portion of the water from the desiccant such that a first exit
stream 71 exiting the
regenerator 52 at a first outlet 72 can be concentrated desiccant and a second
exit stream 73
exiting the regenerator 52 at a second outlet 74 can be distilled water.
(Concentration levels
C1-C3 of the desiccant are described below.) The first exit stream 71 can be
part of the second
desiccant circuit 66. In an example, the first exit stream 71 can be
transported back to the tank
26 via a pump 76.
[0048] The second exit stream 73 (distilled water) can be transported to a
tank 36 for the
evaporative cooler 8, via a pump 78, and used in a first water circuit 30 for
the evaporative
cooler 8. Thus the water in the air stream passing through the plenum 4 can be
absorbed by the
desiccant in the desiccant dryer LAMEE 6, separated from the desiccant in the
regenerator 52,
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and then used as make up water for the evaporative cooler 8. The evaporative
cooler 8 can still
be connected to an external water supply - this is shown in FIG. 1 as external
water supply to
the tank 36. External water can be provided to the evaporative cooler 8 as
needed; however the
use by the evaporative cooler 8 of the recovered water from the desiccant can
result in a
significant reduction or elimination of water for operation of the evaporative
cooler 8. In other
examples, the water in the second exit stream 73 can be used by more than one
cooling unit in a
conditioning system.
[0049] The dilute desiccant exiting the LAMEE 6 at the LAMEE outlet 28 can
have a first
desiccant concentration Cl. The dilute desiccant can be mixed with existing
desiccant in the
tank 26 such that a concentration of desiccant in the tank 26 can be at a
second concentration
C2 that is greater than the first concentration Cl. In an example, a
difference in concentration
between the first concentration Cl and the second concentration C2 can be
small. The desiccant
at the second concentration C2 can be regenerated in the regenerator 52 such
that a third
concentration C3 of the desiccant in the first exit stream 71 can be markedly
greater than the
second concentration C2. The concentrated desiccant in the first exit stream
71 (at the third
concentration C3) can then be mixed with the dilute desiccant exiting the
LAMEE 6 (at the first
concentration Cl), and with the desiccant already in the tank 26, to increase
the second
concentration C2 of the mixed desiccant. As such, the second concentration C2
in the tank 26
can depend on the concentrations Cl and C3, and the volume/flow rate of each,
as well as the
volume of desiccant in the tank 26.
[0050] Even though the mixed desiccant in the tank 26 can be at the second
concentration
C2, which is higher than the first concentration Cl of the dilute desiccant
exiting the LAMEE 6,
the mixed desiccant can be referred to herein as "dilute desiccant" relative
to the concentrated
desiccant exiting the regenerator 52 at the concentration C3. Similarly, the
desiccant entering
the LAMEE can be referred to herein as "concentrated desiccant" relative to
the dilute desiccant
exiting the LAMEE 6, even though the concentration C2 of the desiccant
entering the LAMEE can
be less than the concentration C3 of the desiccant exiting the regenerator 52.
[0051] FIG. 1 shows an exemplary design for the regeneration system 11 in
which the dilute
desiccant exiting the LAMEE 6 can be mixed with the concentrated desiccant
from the
regenerator 52, and a portion of the desiccant exiting the tank 26 can be
circulated back through
the LAMEE 6 and a portion can be regenerated. The valve 68 can control a
distribution of the
desiccant exiting the tank 26 to the LAMEE 6 and to the regeneration system
11. In other
examples, the conditioning system 10 can be configured such that all or a
portion of the dilute
desiccant exiting the LAMEE 6 can be transported directly to the regenerator
52, rather than
mixing the dilute desiccant in the tank 26 with the concentrated desiccant
coming back from the
regenerator 52. This is shown in FIG. 6 and described below.
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[0052] A dehumidification capacity of the LAMEE 6 can depend on a flow
rate, a
temperature, and a concentration of the liquid desiccant passing through the
LAMEE 6. In an
example, the conditioning system 10 can operate with a set point temperature
and a set point
concentration of the liquid desiccant at the LAMEE inlet 34; the flow rate of
the desiccant
through the LAM EE 6 can be generally constant The load on the LAMEE 6 can
vary as the
conditions of the air stream passing through the plenum 4 vary. If the air
stream increases in
humidity, the load on the LAM EE 6 can increase. As a result, the liquid
desiccant exiting the
LAMEE 6 at the outlet 28 can require more regeneration, relative to if the
LAMEE 6 receives a
low humidity air stream. The regeneration system 11 can be configured such
that as additional
regeneration of the desiccant is required, the flow rate of liquid desiccant
to the regenerator 52
can be increased via the modulating valve 68. In an example, the modulating
valve 68 can be
controlled by a system controller 50, described below.
[0053] An increase in the flow rate of liquid desiccant to the regenerator
52 can result in an
increase in the flow rate of concentrated liquid desiccant back to the tank 26
at the
concentration C3. The increased amount of concentrated liquid desiccant can
mix with the
liquid desiccant in the tank 26 to increase the concentration C2 of the liquid
desiccant that is
transported back to the LAMEE 6 (after passing through the LAHX or LLHX 32).
The flow rate of
desiccant to the regenerator 52 can be controlled such that the concentration
C2 can be at or
near the set point concentration for the LAMEE 6 at the LAM EE inlet 34. In an
example, the
concentration C2 can vary (up or down) depending, at least in part, on the
load of the system
(i.e. the outdoor air conditions).
[0054] As an alternative or in addition to using a regeneration system, the
concentration of
the liquid desiccant in the first desiccant circuit 24 can be increased by
introducing a
concentrated desiccant into the desiccant tank 26. This can be done
intermittently as needed or
throughout operation of the system 10.
[0055] The system 10 can be designed such that only a portion of the
desiccant is
regenerated in the regenerator 52. Thus, in an example, the system 10 can
continue operating
efficiently without requiring all of the desiccant to flow through the
regenerator 52. The valve
68 can direct all or a portion of the desiccant from the tank 26 directly back
to the LAMEE 6.
This is a result in part to the mixing in the tank 26 of concentrated
desiccant from the
regeneration system with dilute desiccant from the LAMEE 6. This is also a
result of the design
of the LAM EE 6 which operates at high flow rates of liquid desiccant through
the LAMEE 6.
Because the flow rate of liquid desiccant through the LAMEE 6 is high, a
concentration decrease
of the desiccant in the desiccant stream between the inlet 34 and the outlet
28 of the LAMEE 6 is
small, compared to if the desiccant flow rate was low. As such, in an example,
only a minor
portion of the desiccant from the tank 26 can be diverted for regeneration.
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[0056] The LAMEE 6 is configured such that the desiccant removes at least
one of water and
heat from the air stream. It is recognized that if the desiccant only removes
water from the air
(i.e. the air remains at a generally constant temperature between the LAMEE
inlet and outlet), a
temperature of the desiccant at an outlet of the LAMEE 6 can still be higher
than a temperature
of the desiccant at an inlet of the LAMEE 6. The temperature increase of the
desiccant is due to
the latent heat of condensation of the moisture from the air.
[0057] The design of the LAMEE 6 allows for the desiccant to not only
remove water from
the air stream, but the desiccant can also remove heat from the air stream.
The LAMEE 6 can be
configured such that essentially all of the energy removed from the air stream
is transferred to
the desiccant stream. In other words, an energy reduction of the air in the
air stream between
the LAMEE inlet and outlet can be about equal to an energy gain of the liquid
desiccant in the
desiccant stream between the LAMEE inlet and outlet. It is recognized that
there may be some
loss inherent in the system and 100% of the energy removed from the air stream
may not be
transferred to the desiccant stream. For purposes herein, the term
"essentially all of the energy"
or "all of the energy" recognizes and accounts for such losses in the system.
Similarly, for
purposes herein, "about equal" in reference to the energy reduction of the air
relative to the
energy gain of the desiccant recognizes and accounts for the system not being
100% efficient
and having some loss. The LAMEE 6 can be configured such that a single fluid
(the desiccant)
can be used to remove heat and water from the air. Thus the LAMEE 6 can be a
two-fluid design
- the first fluid is the air stream and the second fluid is the desiccant
Additional fluids are not
included for reducing the energy of the air, and the single desiccant stream
in the LAMEE 6 can
sufficiently remove heat and water from the air stream passing there through.
The heat from
the air stream can primarily be latent heat, although some sensible heat can
also be removed
from the air by the desiccant Because the flow rate of liquid desiccant
through the LAMEE 6 is
high, a temperature increase of the desiccant stream between the inlet 34 and
the outlet 28 of
the LAMEE 6 is small, compared to if the flow rate was low.
[0058] In an example, the flow of liquid desiccant to the LAHX or LLHX 32
can be relatively
constant and the flow of liquid desiccant through the modulating valve 68 can
be variable. It is
recognized that in other examples the flow of liquid desiccant to the LAHX or
LLHX 32 can also
be variable.
[0059] The regenerator 52 can include any type of device capable of
separating liquid water
from the liquid desiccant. For example, the regenerator 52 can include, but is
not limited to,
vacuum multi-effect membrane distillation (VMEMD), electro-dialysis, reverse
osmosis
filtration, a gas boiler with condenser, a vacuum assisted generator, multi-
stage flash,
membrane distillation, and combinations thereof The type of energy input to
the regenerator
52 can include, for example, electrical power, mechanical power, or heat. The
type of energy
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input depends on the technology used for regeneration of the liquid desiccant.
Although the
regenerator 52 is shown as a single unit in FIG. 1, the regenerator 52 can
represent more than
one unit operation. For example, the regeneration system 11 can include a heat
recovery unit
upstream of the regeneration unit This is described further below in reference
to FIGS. 2 and 4.
[0060] The LAHX or LLHX 32 can include any type of device suitable for
cooling the liquid
desiccant For example, the LAHX or LLHX 32 can include, but is not limited to,
a polymer fluid
cooler (with evaporative cooling capability), a plate exchanger, and
combinations thereof In an
example, the LAHX or LLHX 32 can provide air cooling to the liquid desiccant,
using the outdoor
air outside of the conditioning system 10. In another example, the LAHX or
LLHX 32 can
provide liquid cooling to the liquid desiccant using another cooling fluid. In
an example, the
LAHX or LLHX 32 can be located external to the process plenum 4 or the other
components of
the conditioning system 10. In an example, the LAHX or LLHX 32 can be
supplemented with an
evaporative cooler for use as needed, depending on outdoor air conditions. For
example, the
LAHX can be supplemented with evaporative cooling sprays such that the tubes
can be sprayed
with water to enhance the cooling. In an example, an evaporative cooler LAHX
32 can use
water recovered from the regeneration system 11 as make up water for the LAHX
32.
[0061] The design of the regeneration system 11 in combination with the
desiccant dryer
LAMEE 6 can facilitate operation of the conditioning system 10 with little to
no external water
consumption. The LAMEE 6 can remove the water from the air stream and use that
water
(which is separated from the desiccant for regeneration of the desiccant) as
the make up water
supply for one or more evaporative coolers in the conditioning system 10. The
recovered water
can be stored in the tank 36 and can be used as needed. Operation of
evaporative coolers, like
the evaporative cooler 8, can commonly require a significant amount of water.
The conditioning
system 10 having the regeneration system 11 can eliminate or markedly decrease
the external
water needed to operate the system 10. In an example, the system 10 can be
generally water
neutral. In an example, the system 10 can include an external water supply as
back up in the
event that additional water is needed.
[0062] In an example, the LAHX or LLHX 32 may require make up water in an
example in
which the LAHX or LLHX 32 includes evaporative cooling for use as needed. The
evaporative
cooling can be utilized when the outdoor air is at high dry bulb temperatures
and air cooling of
the liquid desiccant is not sufficient to meet a set point temperature for the
desiccant delivered
to the LAMEE 6. It is recognized that the recovered water from the regenerator
system 11 can
be sufficient in some cases to provide the make up water requirements for the
evaporative
cooler 8, as well as an evaporative cooler LAHX 32.
[0063] The design of the regeneration system 11 in combination with the
desiccant dryer
LAMEE 6 can also improve operation of the evaporative cooler 8 since water can
be collected
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directly from the atmosphere. As such, the water recovered from the liquid
desiccant in the
regenerator 52 can be high quality water, which can be ideal for many cooling
applications,
including evaporative coolers. Such high quality water can increase the
lifespan of the media in
the evaporative cooler 8 and can decrease required maintenance on the cooler.
In contrast, if
the water supplied to the evaporative cooler 8 is potable water from wells or
surface water
sources, in some cases, mineral build up or scaling can occur, which may
require the system 10
to include management of mineral concentrations or other water treatment
units. In summary,
the design described herein can reduce or eliminate overall water consumption
of the
conditioning system 10, as well as improve operation of the evaporative cooler
8.
[0064] The system controller 50 can manage operation of the conditioning
system 10,
including the regeneration system 11. The system controller 50 can include
hardware,
software, and combinations thereof to implement the functions attributed to
the controller
herein. The system controller 50 can be an analog, digital, or combination
analog and digital
controller including a number of components. As examples, the controller 50
can include ICB(s),
PCB(s), processor(s), data storage devices, switches, relays, etcetera.
Examples of processors
can include any one or more of a microprocessor, a controller, a digital
signal processor (DSP),
an application specific integrated circuit (ASIC), a field-programmable gate
array (FPGA), or
equivalent discrete or integrated logic circuitry. Storage devices, in some
examples, are
described as a computer-readable storage medium. In some examples, storage
devices include a
temporary memory, meaning that a primary purpose of one or more storage
devices is not long-
term storage. Storage devices are, in some examples, described as a volatile
memory, meaning
that storage devices do not maintain stored contents when the computer is
turned off
Examples of volatile memories include random access memories (RAM), dynamic
random
access memories (DRAM), static random access memories (SRAM), and other forms
of volatile
memories known in the art The data storage devices can be used to store
program instructions
for execution by processor(s) of the controller 50. The storage devices, for
example, are used by
software, applications, algorithms, as examples, running on and/or executed by
the controller
50. The storage devices can include short-term and/or long-term memory, and
can be volatile
and/or non-volatile. Examples of non-volatile storage elements include
magnetic hard discs,
optical discs, floppy discs, flash memories, or forms of electrically
programmable memories
(EPROM) or electrically erasable and programmable (EEPROM) memories.
[0065] The system controller 50 can be configured to communicate with
conditioning
system 10 and components thereof via various wired or wireless communications
technologies
and components using various public and/or proprietary standards and/or
protocols. For
example, a power and/or communications network of some kind may be employed to
facilitate
communication and control between the controller 50 and the conditioning
system 10. In one
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example, the system controller 50 may communicate with the conditioning system
10 via a
private or public local area network (LAN), which can include wired and/or
wireless elements
functioning in accordance with one or more standards and/or via one or more
transport
mediums. In one example, the system 10 can be configured to use wireless
communications
according to one of the 802.11 or Bluetooth specification sets, or another
standard or
proprietary wireless communication protocol. Data transmitted to and from
components of the
system 10, including the controller 50, can be formatted in accordance with a
variety of
different communications protocols. For example, all or a portion of the
communications can be
via a packet-based, Internet Protocol (IP) network that communicates data in
Transmission
Control Protocol/Internet Protocol (TCP/IP) packets, over, for example,
Category 5, Ethernet
cables.
[0066] The system controller 50 can include one or more programs, circuits,
algorithms or
other mechanisms for controlling the operation of the conditioning system 10.
For example, the
system controller 50 can be configured to control the valve 68 in order to
regulate, and vary, as
needed, a volume of desiccant diverted to the regeneration system. In an
example, the system
controller 50 can control the components to maintain a low humidity level or
low temperature
of the supply air. Such control can be based on variable sensible and latent
loads in the enclosed
space. The controller 50 can respond to changing outdoor air conditions or
changing
requirements for ventilation to the enclosed space. In an example, the system
controller 50 can
control or vary an amount of outdoor air added to the plenum 4.
[0067] FIG. 2 depicts another example conditioning system 100 including a
regeneration
system 111. The conditioning system 100 can include many of the components and
functions of
the conditioning system 10 of FIG. 1. The conditioning system 100 can include
a heat recovery
exchanger (HRE) 180, in combination with a regenerator or regeneration unit
152, both of
which can be part of the regeneration system 111. The HRE 180 is not required
for operation of
the conditioning system 100, but, as described below, can facilitate improved
efficiency and
performance of the regeneration system 111. A second desiccant circuit 166 can
include the
HRE 180 and the regenerator 152.
[0068] As stated above in reference to FIG. 1, the regenerator 152 can
include any type of
device capable of separating water from the desiccant. An example is described
below and
illustrated in FIG. 3 which uses a thermally driven separation process. The
regenerator 152 can
include a heat source 151 configured to heat up the desiccant in order to
vaporize the water in
the desiccant. (See FIG. 3.) The HRE 180 can pre-heat the desiccant before the
desiccant is
heated up by the heat source 151. Given the inclusion of the HRE 180, less
heat may be required
from the heat source 151 to vaporize the water in the desiccant stream, as
compared to if the
regenerator 152 operated without the HRE 180.
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[0069] In FIG. 2, the desiccant from the tank 126 passes through the HRE
180 prior to
passing into the regenerator 152. In contrast, the regenerator 52 in FIG. 1 is
shown receiving
the desiccant directly from the tank 26 at the inlet 70. The HRE 180 can be
configured to
exchange heat between the concentrated desiccant exiting the regenerator 152
and the
desiccant entering the regenerator 152. The desiccant can enter the HRE 180 at
an inlet 181
and a temperature Ti. The desiccant can exit the HRE 180 at an outlet 182 and
at a temperature
T2 which can be higher than the temperature Ti. The concentrated desiccant can
enter the HRE
180 at an inlet 183 and a temperature T3. The concentrated desiccant can exit
the HRE 180 at
an outlet 184 and a temperature T4 that can be lower than the temperature T3.
In other words,
the HRE 180 can be configured for the concentrated desiccant coming from the
regenerator 152
to reject heat to the mixed desiccant coming from the tank 126. As a result,
the mixed desiccant
exiting the HRE 180 at the outlet 182 can be pre-heated prior to entering the
regenerator 152.
[0070] The concentrated desiccant exiting the HRE 180 at the outlet 184 can
be
transported to the tank 126 for storage and for circulation back to the LAMEE
106. It can be
advantageous for the concentrated desiccant to be at a reduced temperature T4
to decrease or
maintain a temperature of the desiccant in the tank 126. The temperature of
the desiccant in
the tank 126 can directly impact an amount of heat that has to be rejected
from the desiccant in
the heat exchanger 132. Thus the HRE 180 can serve two benefits - heating the
mixed desiccant
prior to regeneration and cooling the concentrated desiccant prior to
circulation through the
heat exchanger 132 and the LAMEE 106.
[0071] The heat source 151 is shown generally as being provided to the
regenerator 152.
FIG. 3 shows an exemplary heat source and the path of the desiccant through
the HRE 180 and
then through the one or more heat sources 151, prior to entering the
regenerator 152.
[0072] As described above, the conditioning system 100 can receive a
scavenger air stream
or a process air stream, or a combination thereof In an example, the
conditioning system 100
can include two working air streams (and two plenums) or one working air
stream and one
plenum. In such an example with two working air streams, the outdoor
(scavenger) air can be
used to produce cold water in the evaporative cooler (EC) 108 (arranged in the
first plenum
104) and such cold water can be used to provide cooling to a process air
stream passing through
a second (process air) plenum.
[0073] The following numbers are example conditions for the conditioning
system 100,
based on a modeled conditioning system.
[0074] The outdoor air enters the plenum 104 at a dry bulb temperature of
90 degrees
Fahrenheit (32.2 degrees Celsius), a wet bulb temperature of 85 degrees
Fahrenheit (29.4
degrees Celsius), a moisture content of 25.2 g/kg, and a flow rate of 30,000
SCFM. The liquid
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desiccant enters the desiccant dryer LAMEE 106 at the inlet 134 at a
temperature of 34 degrees
Celsius, a concentration of 38% lithium chloride (LiC1) and a flow rate of 250
GPM.
[0075] After exiting the desiccant dryer LAMEE 106, the scavenger air is at
a dry bulb
temperature of 35.6 degrees Celsius and a moisture content of 15.2 g/kg. The
moisture removal
rate is 613.4 kg/hr (0.170 kg/s) and the total cooling is 377 kW.
[0076] The desiccant exits the LAMEE 106 at the outlet 128 at a temperature
of 40.4
degrees Celsius and the concentration Cl is 37.7% LiCl. The dilute desiccant
enters the tank
126 at the concentration Cl and mixes with desiccant in the tank 126. The
concentration C2 of
the mixed desiccant exiting the tank 126 is 38.0% LiC1 and the mixed desiccant
is transported
from the tank 126, via the pump 142, at a flow rate of 275 GPM. A modulating
valve 168 can
divert 25 GPM or 1.58 L/s of desiccant to the HRE 180. The remaining 250 GPM
(15.8 L/s) of
desiccant can flow to the heat exchanger 132 (and then to the LAMEE 106). In
this particular
example, nine percent (9%) of the desiccant exiting the tank 126 is diverted
to the regenerator
152. As described above, in an example, the flow to the heat exchanger 132 can
be generally
constant and a flow to the HRE 180 can be variable, depending, for example, on
the regeneration
load.
[0077] The heat exchanger 132 can decrease a temperature of the desiccant
in the first
desiccant circuit 124 such that the temperature of the desiccant at the inlet
134 is 34 degrees
Celsius.
[0078] The desiccant (at the concentration C2) entering the HRE 180 at the
inlet 181 is
heated up in the HRE 180 from the temperature Ti (40.6 degrees Celsius) to the
temperature
T2 (55.3 degrees Celsius) at the outlet 182. The increased-temperature
desiccant then enters
the regenerator 152 at an inlet 153. As a result of the separation process
that occurs in the
regenerator 152 (see FIG. 3 and description below), the desiccant exits the
regenerator 152 at
an outlet 155 with the concentration C3 equal to 41.7% LiC1 and the
temperature T3 (60.0
degrees Celsius) greater than the temperature T2. The concentrated desiccant
stream (C3) can
be transported to the tank 126 via the pump 176. The temperature Ti (40.6
degrees Celsius) at
the inlet 181 of the HRE 180 can be slightly higher than the temperature at
the LAMEE outlet
128 (40.4 degrees Celsius) because the desiccant from the outlet 128 mixes
with the hot,
concentrated desiccant coming back to the tank 126 at the temperature T4 (43.5
degrees
Celsius). The values provided above for the temperatures T1-T4 are exemplary
based on the
modeled system. It is recognized that temperatures can depend on, at least in
part, the
concentration C2, the concentration C1 and the concentration target for the
inlet 134 to the
LAMEE 106.
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[0079] The collected water can exit the regenerator 152 at the outlet 174
at a rate of 0.17
L/s or 2.7 GPM. The water can be transported to the tank 136, via the pump
178, for use as
make up water by the evaporative cooler 108.
[0080] The concentrated desiccant at the concentration C3 can exit the HRE
180 at the
outlet 184 and at the temperature T4 (43.5 degrees Celsius) and can then be
delivered back to
the tank 126 at a rate of 1.41 L/s or 22.3 GPM. The concentrated desiccant
(C3) at 41.7% LiC1
mixes with the dilute desiccant (Cl) at 37.7% LiC1 to produce the
concentration C2 at 38.0%
LiCl.
[0081] These are exemplary values. It is recognized that the capacity for
the heat exchanger
132, HRE 180 and regenerator 152 can vary depending on the load on the
desiccant dryer
LAMEE 106. Operation of the system 100 can be controlled, in an example, by a
system
controller 150 that can operate similar to the system controller 50 described
above. As
described above in reference to FIG. 1, the modulating valve 168 can be used
to control the flow
or desiccant from the tank 126 through the regenerator and thereby control the
concentration
C2, including maintaining the concentration C2 at or near a target
concentration for the inlet
134.
[0082] FIG. 3 depicts a portion of the regeneration system 111 of FIG. 2
that includes the
HRE 180, the regeneration unit 152 and one or more heat sources 151. As
described above in
reference to FIG. 2, the HRE 180 can receive the mixed desiccant (from the
tank 136) at the inlet
181 (at an increased temperature) and the concentrated desiccant (from the
regenerator 152)
at the inlet 183. The concentrated, increased-temperature desiccant exiting
the regenerator
152 (C3, T3) can transfer heat to the mixed desiccant from the tank 136 (C2,
Ti). The
concentrated desiccant at the outlet 184 (C3, T4) can flow back to the tank
136. The mixed
desiccant at the outlet 182 (C2, T2) can flow to the regeneration unit 152.
[0083] In an example, the one or more heat sources 151 can include solar
collectors 185
and an auxiliary heater 187. Prior to passing into the regeneration unit 152,
the mixed
desiccant can flow through the one or more solar collectors 185 that can use
energy from the
sun 186 to further increase a temperature of the desiccant before the
desiccant flows through
the regenerator 152. In an example, the two collectors 185 of FIG. 3 can be
evacuated tube solar
collectors that can circulate the desiccant through the tubes prior to passing
the desiccant to the
regenerator 152. In another example, the solar collectors can be a flat plate
design.
[0084] The regeneration system 111 can include an auxiliary heater 187
located between
the solar collectors 185 and the regeneration unit 152. The auxiliary heater
187 can use various
sources to increase a temperature of the desiccant before the desiccant enters
the regeneration
unit 152. Such sources can include, but are not limited to, gas, waste heat,
and combustion of a
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fuel. The auxiliary heater 187 can run intermittently depending on, at least
in part, the load of
the regeneration unit 152 and heating (if any) provided by the solar
collectors 185.
[0085] The solar collectors 185 and the heater 187 can increase a
temperature of the
desiccant prior to separating the water and the desiccant in the regeneration
unit 152. The
vapor pressure can increase quickly as the desiccant temperature increases,
resulting in a large
flux of water vapor out of the desiccant stream. It is not required that the
regeneration system
111 include both the tube collectors 185 and the auxiliary heater 187. In
other examples, either
the tube collectors 185 or the auxiliary heater 187 can be used. In other
examples, other forms
of heating can be used for heat sources 151 in addition or as an alternative
to the tube collectors
185 and auxiliary heater 187.
[0086] The desiccant exiting the auxiliary heater 187 can enter the
regeneration unit 152 as
hot desiccant. In an example, a temperature at an inlet of the regenerator 152
can be
approximately 80 degrees Celsius. In order for the regenerator 152 to be
effective, the desiccant
stream has to be hot enough to vaporize the water from the desiccant stream.
In an example,
the regeneration unit 152 can separate the water and desiccant using a
membrane distillation
separation process. In such an example, and as detailed below, the
regeneration unit 152 can
include a vaporizing section 188 and a condensing section 179.
[0087] The vaporizing section 188 can have a plurality of channels 189 and
a corresponding
membrane 190 for each of the channels 189. The desiccant can be directed into
each of the
channels and can flow inside and down the channels 189. The materials that
form the
membrane can be permeable to water but not permeable for the desiccant. Each
membrane
190 can contact an exterior of its corresponding channel such that the
membrane 190 creates a
seal around the channel 189. As the hot desiccant travels down the channels
189, water can be
released from the desiccant, as water vapor. The water vapor can permeate
through the
membranes 190, and thus out of the channels 189. The desiccant, which can
remain in liquid
form, can be contained inside the channels 189 by the membranes 190 and can
travel down the
channels to the manifold 191. The manifold 191 can transport the increased
concentration
desiccant (C3) out of the regenerator 152 and to the HRE 180. As discussed
above, the
increased concentration desiccant can be cooled in the HRE 180 prior to being
transported to
the tank 136.
[0088] The water vapor from the vaporizing section 188 can travel to the
condensing
section 179, which can include a plurality of channels 192 that function as
cooling channels 192.
Although not shown in FIG. 3, the regeneration unit 152 can include an inlet
to and an outlet
from the channels 192 for the air source used to provide cooling to the water
vapor. The water
vapor can pass over the outside of the channels 192 and the water vapor can
condense on the
surface of the cooling channels 192 as a result of a cooling fluid flowing
inside the channels 192.
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The cooling fluid can be any fluid (liquid or gas) suitable for cooling the
surrounding material
such that the water vapor condenses on the exterior surfaces that form the
channels 192. In an
example, the cooling fluid can be air. The air can be from any source that is
at favorable
conditions for providing air cooling to the water vapor. Examples of the air
source can include,
but are not limited to, outdoor air or exhaust air from an outlet of the heat
exchanger 132. In an
example, a regeneration unit similar to unit 152 can be used in a conditioning
system for a
process air stream and such conditioning system can include an exhaust air
stream that includes
an exhaust LAMEE. In such an example, the exhaust air from the exhaust LAMEE
outlet can be
used as the air source for the air cooling channels 192. The air circulating
through the channels
192 can be relatively humid, so long as the air is still relatively cool. In
an example, the cooling
fluid can be water.
[0089] The condensate (distilled water) can be collected through gravity by
a water
collection sump 193 at the bottom of the regeneration unit 152. The sump 193
can be at the
bottom of or connected to the outlet 174 of the regeneration unit 152 and the
distilled water can
be transported from the sump 193 to other parts of the conditioning system,
such as, for
example, one or more evaporative coolers. In an example, as shown in FIG. 3,
the water can be
delivered to the tank 136 for use as make up water for the evaporative cooler
108. This can
reduce or eliminate an external water supply for operating the conditioning
system 100.
[0090] FIG. 3 illustrates one example of a regeneration unit that can
include a thermally-
driven separation process. It is recognized that other types of regeneration
can be used to
separate the desiccant from the water, including, but not limited to, those
listed above in
reference to FIG. 1.
[0091] FIG. 4 depicts another example conditioning system 200 including a
regeneration
system 211. FIG. 4 illustrates exemplary sources of heat that can be used to
drive operation of a
regenerator 252 in the regeneration system 211. FIG. 4 also illustrates an
exemplary design
having a concentrated desiccant storage tank 294 and a distilled water storage
tank 296,
described further below.
[0092] A desiccant dryer LAMEE 206 is shown in FIG. 4 and, in an example,
can be used in
combination with an evaporative cooler located downstream of the LAMEE 206, as
described
above in reference to FIGS. 1 and 2. In other examples, other coolers can be
included in the
system 200, such as, for example, a liquid to air heat exchanger (LAHX)
located between the
desiccant dryer LAMEE and the evaporative cooler.
[0093] As described above in reference to FIGS. 2 and 3, the desiccant from
the LAMEE 206
can be directly heated (using any type of heat source) prior to circulating
the desiccant through
the regeneration unit 152. In another example, the desiccant can be heated up
using a heat
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transfer fluid. The heat transfer fluid can be heated and then transfer heat
to the desiccant -
this is shown in FIG. 4.
[0094] The conditioning system 200 can include a heating fluid circuit 298
for circulating a
heating fluid through the regenerator 252 of the regeneration system 211. The
heating fluid
circuit 298 can include a solar thermal array 285 and an auxiliary heater 287.
In an example,
the solar thermal array 285 can be configured similar to the solar collectors
185 of FIG. 3. The
solar thermal array 285 can include first and second solar devices 285a and
285b, which can
include, for example, flat plate collectors or evaluated tube collectors. The
auxiliary heater 287
can be similar to the auxiliary heater 187 of FIG. 3.
[0095] The regenerator or regeneration unit 252 can be similar to the unit
152 shown in
FIG. 3, but can also include a liquid-to-liquid heat exchanger (LLHX)
contained within the
heating fluid circuit 298. The LLHX can be inside the regenerator unit 252
upstream of the
vaporizing section (see section 188 of FIG. 3) or the LLHX can be external to
the regeneration
unit 252 and located upstream of the desiccant inlet to the regeneration unit.
Instead of heating
up the desiccant with the solar thermal array 285 or auxiliary heater 287, the
solar thermal
array 285 or auxiliary heater 287 can heat up the heating fluid and then the
heating fluid can
transfer heat to the desiccant in the LLHX. The hot desiccant can then be
processed through the
regenerator 252 as described above in reference to FIG. 3.
[0096] In an example, the heating fluid can be a glycol solution. The
heating fluid can be any
type of liquid suitable for transferring heat to the desiccant such that the
desiccant is heated up
prior to passing through the vaporizing section in the regenerator 252. Other
examples include,
but are not limited to, water and oil.
[0097] One or both of the solar thermal array 285 and the heater 287 can be
an intermittent
or continuous heat source. In an example, the auxiliary heater 287 can use
waste heat from
another source within the system 200. In another example, the auxiliary heater
287 can use gas
as a heat source.
[0098] In an example, the regenerator system 211 can operate when heat
(solar heat, waste
heat, etc.) is available to operate the regenerator and separate the water
from the desiccant.
The concentrated desiccant from the regenerator 252 can be transported to a
concentrated
desiccant storage tank 294. Similarly, the distilled water from the
regenerator 252 can be
transported to a distilled water storage tank 296. The concentrated desiccant
can be drawn
from the storage tank 294 as needed and supplied to a desiccant tank 226 (as
shown in FIG. 4)
via a pump 295. Alternatively, the concentrated desiccant can be transported
directly to the
heat exchanger 232 or to the LAMEE 206. Similarly, the distilled water can be
drawn from the
storage tank 296 as needed and supplied to one or more evaporative coolers in
the conditioning
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system 200 via a pump 297. One or both of the tanks 294 and 296 can be
included in the other
conditioning systems described herein and shown in FIGS. 1 and 2.
[0099] The
regeneration system 211 can operate similar to the regen systems 11 and 111 of
FIGS. 1 and 2, respectively, and a portion of the desiccant from the tank 226
can be transported
to the regenerator 252 for regeneration. A larger portion of the desiccant
from the tank 226 can
be transported to the heat exchanger 232 and back to the LAMEE 206. Instead of
a modulating
valve (see valves 68 and 168) as shown in FIGS. 1 and 2, the system 200 can
include two pumps
in fluid connection with the desiccant tank 226. A first pump 242 can deliver
desiccant from the
tank 226 to the LAMEE 206 and a second pump 243 can deliver desiccant from the
tank 226 to
the regenerator 252. This two pump design of FIG. 4 can also be used in the
design of FIGS. 1
and 2. Similarly, the modulating valve design of FIGS. 1 and 2 can also be
used in the design of
FIG. 4. A system controller can control a flow rate of the desiccant to the
LAMEE 206 and a flow
rate of the desiccant to the regenerator 252. One or both of such flow rates
can be constant or
variable.
[00100] Although a heat recovery exchanger is not shown in FIG. 4, it is
recognized that an
HRE could be included in the conditioning system 200 upstream of the
regenerator 252 and
operate similar to the HRE 180 of FIG. 2.
[00101] FIG. 5 depicts an example system 300, which can include a plurality of
desiccant
dryer LAMEEs 306. Each of the desiccant dryer LAMEEs 306a, 306b and 306c can
be part of a
conditioning unit 301a, 301b and 301c, respectively, that can include an air
plenum containing
the desiccant dryer LAMEE and an evaporative cooler (EC) downstream of the
desiccant dryer
LAMEE. Each conditioning unit 301a, 301b and 301c can thus function similar to
any of the
conditioning systems described herein, including the conditioning systems 10
and 100 of FIGS. 1
and 2, respectively.
[00102] Instead of each conditioning unit 301a, 301b and 301c having its own
regeneration
system, the system 300 can include a centralized regenerator plant 303 having
capacity to
regenerate a portion of the desiccant from each of the LAMEEs 306a, 306b and
306c. The
regenerator plant 303 can include some or all of the components described
herein such as a
heat recovery exchanger, heating fluid, solar thermal array, etc. For
simplicity, these additional
components are not specifically shown in FIG. 5, but rather a heat input to
the plant 303 is
generically shown in the schematic.
[00103] Each conditioning unit 301a, 301b and 301c can have a desiccant
circuit 366a, 366b
and 366c in fluid connection with a tank 326a, 326b and 326c and with the
centralized
regenerator plant 303. The desiccant in the desiccant circuits 366a, 366b and
366c can be at a
concentration C2 at an inlet 370 to the regenerator plant 303. The desiccant
can be regenerated
in the plant 303 (as described above) such that a first outlet stream 371
exiting the plant 303 at
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an outlet 372 can be concentrated desiccant at a concentration C3 and a second
outlet stream
373 exiting the plant 303 at an outlet 374 can be distilled water. The
concentrated desiccant
can be transported to a concentrated desiccant storage tank 394 and the
distilled water can be
transported to a distilled water storage tank 396.
[00104] As described above in reference to FIG. 4, the concentrated desiccant
from the
storage tank 394 can be transported back to each of the units 301 via a
centralized output
stream 367 from the tank 394. The stream 367 can be fluidly connected to an
input stream that
forms part of the desiccant circuit 366 for each of the units 301. In an
example, the
concentrated desiccant at the concentration C3 can be delivered back to the
tank 326 for each
conditioning unit 301. The distilled water from the storage tank 396 can be
supplied to each
conditioning unit 301 via a water stream 375 from the storage tank 396. As
described above,
the distilled water can be used as make up water for one or more evaporative
coolers in the
conditioning units 301. The system 300 can also include an external water
supply of
potable/treated water which can be delivered via a water stream 377 that is in
fluid connection
with the water stream 375. Such external water can be used as backup for the
conditioning
system 300 if and when the distilled water is not sufficient as the make up
water for the
conditioning units 301.
[00105] In an example, the conditioning units 301 can be used to provide
cooling for a data
center, and the conditioning units 301 can be located on a roof of the data
center. The example
of FIG. 5 shows three conditioning unit 301. It is recognized that the system
300 can include
any number of conditioning units. Depending on the number of conditioning
units 301, more
than one regenerator plant 303 can be used in combination with the
conditioning units 301. In
one example, the regenerator plant 303 can be housed within a desiccant
treatment room that
can be contained within the data center or external to the data center.
[00106] As shown in FIG. 5, each conditioning unit 301 can receive
concentrated desiccant
from the tank 394 and distilled water from the tank 396. In another example,
each conditioning
unit 301 can have a dedicated desiccant tank and dedicated water tank.
[00107] FIG. 6 shows an example conditioning system 400 that can be similar to
the
conditioning systems 10, 100 and 200 but can include an alternative design for
the fluid circuits
for regeneration. Only a portion of the system 400 is shown in FIG. 6 for
simplicity and it is
recognized that additional components can be included. For example, only a
portion of a system
cabinet 402 and plenum 404 is shown in FIG. 6, but it is recognized that the
plenum 404 can
include some or all of the additional components shown and described above in
reference to
FIGS. 1, 2 and 4.
[00108] The desiccant dryer LAMEE 406 can operate similar to the desiccant
dryer LAMEEs
described above. The dilute desiccant exiting the desiccant dryer LAMEE 406 at
an outlet 428
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can be split into two flow paths - a first flow path to a tank 426 or a second
flow path directly to
a regenerator 452 (via a desiccant circuit 466). The regenerator 452 can
operate similar to the
regenerators described above. The desiccant entering the regenerator 452 at an
inlet 470 can
be at a first concentration Cl. The concentrated desiccant exiting the
regenerator 452 at an
outlet 472 can be at a third concentration C3 and can be transported to the
tank426 for mixing
with the desiccant already in the tank 426. As such, the desiccant in the tank
426 can be at a
second concentration C2 that is greater than the first concentration Cl and
less than the third
concentration C3.
[00109] In contrast to the designs shown in FIGS. 1,2 and 4, instead of the
dilute desiccant
(at the concentration Cl) mixing with the desiccant in the tank and then
flowing to the
regenerator (at the second concentration C2), the dilute desiccant exiting the
LAMEE 406 in FIG.
6 is transported directly to the regenerator 452 at the first concentration Cl
(via a pump 467).
All of the desiccant exiting the tank 426 at the second concentration C2 is
circulated through the
heat exchanger 432 and back through the LAMEE 406, rather than selectively
directing a
portion of the desiccant at the second concentration C2 to the regenerator
452. Thus in the
design of FIG. 6 the split of the desiccant flow path is at the outlet 428 of
the LAMEE 406, rather
than at an outlet of the tank 426.
[00110] The pump 467 is shown in the desiccant circuit 466 and is an example
of a device for
regulating or controlling a flow of the dilute desiccant to the regenerator
452. As described
above in reference to the other example conditioning systems, in an example,
generally during
operation of the system only a portion of the dilute desiccant exiting the
LAMEE 406 is sent to
the regenerator 452. The amount of desiccant transported to the regenerator
452 can be
variable and a percentage of the desiccant at the outlet 428 can be directed
to the regenerator
and a remaining percentage of the desiccant at the outlet 428 can be directed
to the tank 426.
Such percentages can depend in part on a load of the conditioning system 400.
[00111] FIG. 7 illustrates an example method 700 for conditioning air for
delivery to an
enclosed space according to the example conditioning systems described above.
The method
700 can reduce or eliminate an external water supply to the conditioning
systems. The method
700 can include at 702 directing air through a desiccant dryer LAMEE arranged
in a process
plenum and at 704 directing a concentrated desiccant into and through the
LAMEE to remove
moisture from the air. In an example, the LAMEE at 702 can also be configured
such that the
desiccant can also remove heat from the air, such that a temperature of the
desiccant at the
LAMEE outlet is higher than a temperature of the desiccant at the LAMEE inlet
The air stream
flowing through the LAMEE can be outdoor air, hot supply air from the enclosed
space, or a
combination thereof The conditioning systems can include one working air
stream (which
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passes through the process plenum) or two working air streams - a first air
stream containing
scavenger air and a second air stream containing process air.
[00112] The method 700 can include at 706 regenerating the diluted desiccant
exiting the
LAMEE to separate the water from the desiccant, before recirculating the
desiccant back
through the LAMEE. In an example, only a portion of the desiccant exiting the
LAMEE can be
regenerated. The regeneration step can result in a concentrated desiccant
output stream and a
distilled water output stream.
[00113] The method 700 can include at 708 directing concentrated desiccant
from the
regenerator back to a fluid circuit for the desiccant dryer LAMEE. In an
example, the
concentrated desiccant can be directed to a desiccant tank which can also
receive the diluted
desiccant exiting the LAMEE. The diluted desiccant and concentrated desiccant
can mix such
that the desiccant in the tank can be at a concentration higher than the
diluted desiccant exiting
the LAMEE and lower than the concentrated desiccant exiting the regenerator.
The desiccant
tank can be contained within the desiccant fluid circuit that passes through
the LAMEE.
[00114] The method 700 can include at 710 directing distilled water from the
regenerator to
one or more evaporative coolers in the conditioning system. In an example, the
one or more
evaporative coolers can include an evaporative cooler arranged in the plenum
downstream of
the desiccant dryer LAMEE, and the recovered water from the regenerator can be
used as make
up water for operation of the evaporative cooler. In an example in which the
conditioning
system uses two working air streams and two plenums, the evaporative cooler in
the first
plenum can be used to cool the water passing there through and the cooled
water can delivered
to an LAHX in the second plenum to cool a process air stream passing through
the second
plenum. In an example, the one or more evaporative coolers can include a LAHX
in the
desiccant circuit, which can be configured to cool the desiccant prior to
flowing the desiccant
through the desiccant dryer LAMEE. The LAHX can be internal or external to the
plenum
containing the desiccant dryer LAMEE. The LAHX can include evaporative cooling
capabilities
and can use recovered water from the regenerator as make up water for
operation of the
evaporative cooler LAHX. The use of the water recovered from regeneration by
one or more
evaporative coolers in the system can markedly reduce or eliminate the
external water supply
for operation of the conditioning system.
[00115] It is recognized that the method 700 for conditioning the air can
include other steps
not included in FIG. 7. Such other steps can include, but are not limited to,
directing air through
a pre-cooler or LAHX arranged in the process plenum downstream of the LAMEE
and upstream
of the evaporative cooler. In an example, directing air through the LAMEE in
702 can include
mixing process air with outdoor air upstream of the LAMEE to create a mixed
air stream that
passes through the process plenum. In an example, the method 700 can include
removing a
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portion of the air in the mixed stream, at a location downstream of the pre-
cooler and upstream
of the evaporative cooler, to create an exhaust air stream and utilizing the
exhaust air stream to
cool the cooling fluid circulating through the pre-cooler. In an example, the
method 700 can
include directing cooled water from the evaporative cooler in the first plenum
to an LAHX in the
second plenum to cool process air passing through the second plenum.
[00116] The above detailed description includes references to the accompanying
drawings,
which form a part of the detailed description. The drawings show, by way of
illustration,
specific embodiments in which the invention can be practiced. These
embodiments are also
referred to herein as "examples." Such examples can include elements in
addition to those
shown or described. However, the present inventors also contemplate examples
in which only
those elements shown or described are provided. Moreover, the present
inventors also
contemplate examples using any combination or permutation of those elements
shown or
described (or one or more aspects thereof), either with respect to a
particular example (or one
or more aspects thereof), or with respect to other examples (or one or more
aspects thereof)
shown or described herein.
[00117] All publications, patents, and patent documents referred to in this
document are
incorporated by reference herein in their entirety, as though individually
incorporated by
reference. In the event of inconsistent usages between this document and those
documents so
incorporated by reference, the usage in the incorporated reference (s) should
be considered
supplementary to that of this document; for irreconcilable inconsistencies,
the usage in this
document controls.
[00118] In this document, the terms "a" or "an" are used, as is common in
patent documents,
to include one or more than one, independent of any other instances or usages
of "at least one"
or "one or more." In this document, the term "or" is used to refer to a
nonexclusive or, such that
"A or B" includes "A but not B," "B but not A," and "A and B," unless
otherwise indicated. In this
document, the terms "including" and "in which" are used as the plain-English
equivalents of the
respective terms "comprising" and "wherein." Also, in the following claims,
the terms
"including" and "comprising" are open-ended, that is, a system, device,
article, or process that
includes elements in addition to those listed after such a term in a claim are
still deemed to fall
within the scope of that claim. Moreover, in the following claims, the terms
"first," "second," and
"third," etc. are used merely as labels, and are not intended to impose
numerical requirements
on their objects.
[00119] Method examples described herein can be machine or computer-
implemented at
least in part. Some examples can include a computer-readable medium or machine-
readable
medium encoded with instructions operable to configure an electronic device to
perform
methods as described in the above examples. An implementation of such methods
can include
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code, such as microcode, assembly language code, a higher-level language code,
or the like. Such
code can include computer readable instructions for performing various
methods. The code
may form portions of computer program products. Further, the code can be
tangibly stored on
one or more volatile or non-volatile tangible computer-readable media, such as
during
execution or at other times. Examples of these tangible computer-readable
media can include,
but are not limited to, hard disks, removable magnetic disks, removable
optical disks (e.g.,
compact disks and digital video disks), magnetic cassettes, memory cards or
sticks, random
access memories (RAMs), read only memories (ROMs), and the like.
[00120] Examples, as described herein, may include, or may operate on, logic
or a number of
components, modules, or mechanisms. Modules may be hardware, software, or
firmware
communicatively coupled to one or more processors in order to carry out the
operations
described herein. Modules may hardware modules, and as such modules may be
considered
tangible entities capable of performing specified operations and may be
configured or arranged
in a certain manner. In an example, circuits may be arranged (e.g., internally
or with respect to
external entities such as other circuits) in a specified manner as a module.
In an example, the
whole or part of one or more computer systems (e.g., a standalone, client or
server computer
system) or one or more hardware processors may be configured by firmware or
software (e.g.,
instructions, an application portion, or an application) as a module that
operates to perform
specified operations. In an example, the software may reside on a machine-
readable medium.
In an example, the software, when executed by the underlying hardware of the
module, causes
the hardware to perform the specified operations. Accordingly, the term
hardware module is
understood to encompass a tangible entity, be that an entity that is
physically constructed,
specifically configured (e.g., hardwired), or temporarily (e.g., transitorily)
configured (e.g.,
programmed) to operate in a specified manner or to perform part or all of any
operation
described herein. Considering examples in which modules are temporarily
configured, each of
the modules need not be instantiated at any one moment in time. For example,
where the
modules comprise a general-purpose hardware processor configured using
software; the
general-purpose hardware processor may be configured as respective different
modules at
different times. Software may accordingly configure a hardware processor, for
example, to
constitute a particular module at one instance of time and to constitute a
different module at a
different instance of time. Modules may also be software or firmware modules,
which operate
to perform the methodologies described herein.
[00121] The above description is intended to be illustrative, and not
restrictive. For
example, the above-described examples (or one or more aspects thereof) may be
used in
combination with each other. Other embodiments can be used, such as by one of
ordinary skill
in the art upon reviewing the above description. Also, in the above Detailed
Description, various
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features may be grouped together to streamline the disclosure. This should not
be interpreted
as intending that an unclaimed disclosed feature is essential to any claim.
Rather, inventive
subject matter may lie in less than all features of a particular disclosed
embodiment. Thus, the
following claims are hereby incorporated into the Detailed Description, with
each claim
standing on its own as a separate embodiment, and it is contemplated that such
embodiments
can be combined with each other in various combinations or permutations. The
scope of the
invention should be determined with reference to the appended claims, along
with the full
scope of equivalents to which such claims are entitled.
[00122] The present application provides for the following exemplary
embodiments or
examples, the numbering of which is not to be construed as designating levels
of importance:
[00123] Example 1 provides a system for conditioning air for an enclosed
space. The system
can include a plenum having a plenum inlet and outlet, the plenum configured
to direct an air
flow path from the plenum inlet to the plenum outlet, and a liquid-to-air
membrane energy
exchanger (LAMEE) arranged inside the plenum. The LAMEE can comprise a
desiccant flow
path separated from the air flow path by a membrane. The LAMEE can be
configured to
circulate a desiccant through the desiccant flow path and remove water from
air in the air flow
path. An energy reduction of the air in the air flow path between a LAMEE
inlet and outlet can
be about equal to an energy gain of the desiccant in the desiccant flow path
between the LAMEE
inlet and outlet, and essentially all of the energy removed from the air is
transferred to the
desiccant. The system can also include a regeneration system in fluid
connection with the
LAMEE and having a regeneration inlet configured to receive a dilute desiccant
stream. The
regeneration system can be configured to separate water from desiccant in the
dilute desiccant
stream, the regeneration system having a first outlet for discharging a
concentrated desiccant
stream and a second outlet for discharging a water stream. The system can also
include one or
more cooling components arranged inside the plenum, and at least a portion of
the water
stream from the regeneration system can be used by the one or more cooling
components as
make up water for operation of the one or more cooling components.
[00124] Example 2 provides the system of Example 1 optionally configured such
that the
regeneration system comprises a regeneration unit that thermally separates the
water and the
desiccant in the dilute desiccant stream.
[00125] Example 3 provides the system of Example 2 optionally configured such
that the
regeneration system comprises a heat exchanger arranged upstream of the
regeneration unit
and configured to increase a temperature of the dilute desiccant stream before
the dilute
desiccant stream enters the regeneration unit
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[00126] Example 4 provides the system of Example 3 optionally configured such
that the
heat exchanger receives the concentrated desiccant stream from the
regeneration unit and uses
the concentrated desiccant stream to transfer heat to the dilute desiccant
stream.
[00127] Example 5 provides the system of any of Examples 2-4 optionally
configured such
that the regeneration system comprises a heat source to increase a temperature
of the dilute
desiccant stream.
[00128] Example 6 provides the system of Example 5 optionally configured such
that the
heat source is solar.
[00129] Example 7 provides the system of Example 1 optionally configured such
that the
regeneration system comprises a regeneration unit that utilizes non-thermal
energy to separate
the water and the desiccant in the dilute desiccant stream.
[00130] Example 8 provides the system of any of Examples 1-7 optionally
configured such
that the concentrated desiccant stream is transported to a desiccant tank
configured to receive
the concentrated desiccant stream and a dilute desiccant stream exiting the
LAMEE.
[00131] Example 9 provides the system of Example 8 optionally configured such
that an
output stream from the desiccant tank is at a concentration higher than a
concentration of the
desiccant in the dilute desiccant stream and lower than a concentration of the
desiccant in the
concentrated desiccant stream.
[00132] Example 10 provides the system of Example 9 optionally configured such
that the
output stream from the desiccant tank is transported to at least one of the
regeneration system
and to the LAMEE for recirculation.
[00133] Example 11 provides the system of Example 10 optionally further
comprising a
modulating valve configured to control a distribution of the output stream
from the desiccant
tank to the regeneration system and to the LAMEE.
[00134] Example 12 provides the system of Example 11 optionally configured
such that less
than 50 percent by volume of the output stream from the desiccant tank is
transported to the
regeneration system.
[00135] Example 13 provides the system of Example 11 optionally configured
such that less
than 25 percent by volume of the output stream from the desiccant tank is
transported to the
regeneration system.
[00136] Example 14 provides the system of any of Examples 10-13 optionally
configured
such that a portion of the output stream from the desiccant tank being
transported to the
LAMEE passes through a heat exchanger prior to being circulated through the
LAMEE. The heat
exchanger can reduce a temperature of the output stream from the desiccant
tank.
[00137] Example 15 provides the system of Example 8 optionally configured such
that a first
portion of the dilute desiccant stream exiting the LAMEE is transported to the
desiccant tank
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and a second portion of the dilute desiccant stream exiting the LAMEE is
transported to the
regeneration system.
[00138] Example 16 provides the system of Example 15 optionally configured
such that the
first and second portions are variable during operation of the system.
[00139] Example 17 provides the system of any of Examples 1-16 optionally
configured such
that a concentration of water in the desiccant at the LAMEE outlet is higher
than a concentration
of water in the desiccant at the LAMEE inlet.
[00140] Example 18 provides the system of any of Examples 1-17 optionally
configured such
that a temperature of the desiccant at the LAMEE outlet is higher than a
temperature of the
desiccant at the LAMEE inlet
[00141] Example 19 provides the system of any of Examples 1-18 optionally
configured such
that the LAMEE is a two-fluid LAMEE having a first fluid and a second fluid,
and wherein the
first fluid is the air in the air flow path and the second fluid is the
desiccant in the desiccant flow
path.
[00142] Example 20 provides the system of any of Examples 1-19 optionally
configured such
that the one or more cooling components comprises an evaporative cooler
arranged
downstream of the LAMEE.
[00143] Example 21 provides the system of any of Examples 1-20 optionally
configured such
that a quantity of water from the regeneration system is sufficient as the
make up water for
operation of the evaporative cooler such that the evaporative cooler operates
without an
external water supply.
[00144] Example 22 provides the system of any of Example 20 or 21 optionally
configured
such that
[00145] the LAMEE arranged inside the plenum is a first LAMEE, and the
evaporative cooler
arranged downstream is a second LAMEE.
[00146] Example 23 provides the system of Example 22 optionally configured
such that the
second LAMEE adiabatically cools the air passing through the process plenum
such that the air
exiting the second LAMEE is conditioned air for delivery to an enclosed space.
[00147] Example 24 provides the system of any of Examples 1-23 optionally
configured such
that the one or more cooling components comprises an evaporative cooler
configured to cool
the desiccant prior to circulating the desiccant through the LAMEE.
[00148] Example 25 provides the system of Example 24 optionally configured
such that the
evaporative cooler is external to the plenum.
[00149] Example 26 provides the system of any of Examples 21-25 optionally
further
comprising a liquid to air heat exchanger (LAHX) arranged between the LAMEE
and the
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evaporative cooler, the LAHX configured to pre-cool the air prior to passing
the air through the
evaporative cooler.
[00150] Example 27 provides the system of any of Examples 1-26 optionally
configured such
that the plenum is a first plenum configured to receive a scavenger air
stream, and the system
further comprises a second plenum configured to receive a process air stream
from an enclosed
space.
[00151] Example 28 provides the system of Example 27 optionally configured
such that the
one or more cooling components comprises an evaporative cooler arranged
downstream of the
LAMEE in the first plenum, the evaporative cooler configured to produce
reduced temperature
water. The reduced temperature water can be transported to an LAHX arranged in
the second
plenum, and the reduced temperature water can be used to cool the process air
stream flowing
through the LAHX.
[00152] Example 29 provides a system for conditioning air for an enclosed
space, the system
can include a plenum configured to direct air from an inlet to an outlet
thereof, a desiccant dryer
liquid-to-air membrane energy exchanger (LAMEE) arranged inside the plenum and
configured
for the air to pass there through, the desiccant dryer LAMEE configured to use
a desiccant
flowing there through to remove water from the air. The desiccant and air can
be separated in
the LAMEE by a membrane. The LAMEE can facilitate an energy exchange between
the air and
the desiccant, and the desiccant can collect essentially all of the energy
removed from the air.
The system can also include an evaporative cooler arranged inside the plenum
downstream of
the desiccant dryer LAM EE and configured for the air to pass there through,
the evaporative
cooler configured to cool at least one of the air and water circulating
through the evaporative
cooler. The system can also include a fluid circuit coupled to the desiccant
dryer LAMEE and the
evaporative cooler. The fluid circuit can comprise a regenerator configured to
separate water
and desiccant in a desiccant stream. The fluid circuit can be configured to
transport at least a
portion of the water removed from the air by the desiccant dryer LAMEE and
separated in the
regenerator to the evaporative cooler for use as make up water for operation
of the evaporative
cooler.
[00153] Example 30 provides the system of Example 29 optionally configured
such that the
fluid circuit receives an output desiccant stream from a desiccant tank in
fluid connection with
an outlet of the LAMEE.
[00154] Example 31 provides the system of Example 30 optionally configured
such that the
desiccant tank is in fluid connection with an outlet of the regenerator such
that the desiccant
tank receives a concentrated input desiccant stream discharged from the
regenerator and a
dilute input desiccant stream exiting the LAMEE.
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[00155] Example 32 provides the system of Example 31 optionally configured
such that the
fluid circuit is a first desiccant circuit and the system further comprises a
second desiccant
circuit, the LAMEE being contained within the second desiccant circuit The
output desiccant
stream from the desiccant tank can be directed to a modulating valve
configured to distribute
the output desiccant stream to the first desiccant circuit and the second
desiccant circuit
[00156] Example 33 provides the system of Example 32 optionally configured
such that a
larger percentage by weight of the output desiccant stream is directed to the
second desiccant
circuit compared to the first desiccant circuit
[00157] Example 34 provides the system of any of Examples 29-33 optionally
configured
such that the regenerator comprises a thermal separation unit.
[00158] Example 35 provides the system of Example 34 optionally configured
such that the
regenerator comprises one or more heat sources to increase a temperature of
the desiccant
stream prior to passing the desiccant stream into the thermal separation unit
[00159] Example 36 provides the system of Example 35 optionally configured
such that the
one or more heat sources includes solar energy.
[00160] Example 37 provides the system of Example 35 or 36 optionally
configured such
that the one or more heat sources includes a heat exchanger configured to use
a liquid to
transfer heat to the desiccant stream.
[00161] Example 38 provides the system of Example 37 optionally configured
such that the
liquid is a concentrated desiccant stream exiting the regenerator, and the
concentrated
desiccant stream increases a temperature of the desiccant stream prior to
passing the desiccant
stream into the thermal separation unit.
[00162] Example 39 provides the system of Example 37 optionally configured
such that the
liquid is a heat transfer fluid configured to transfer heat to the desiccant
stream prior to passing
the desiccant stream into the thermal separation unit
[00163] Example 40 provides the system of any of Examples 29-39 optionally
configured
such that the fluid circuit comprises a concentrated desiccant storage tank
configured to receive
a concentrated desiccant stream output from the regenerator.
[00164] Example 41 provides the system of Example 40 optionally configured
such that the
concentrated desiccant storage tank delivers concentrated desiccant to at
least one of a mixing
tank and the LAMEE.
[00165] Example 42 provides the system of Example 41 optionally configured
such that the
concentrated desiccant is delivered intermittently as needed to increase a
concentration of the
desiccant in an input stream to the LAMEE.
[00166] Example 43 provides the system of any of Examples 29-42 optionally
configured
such that the fluid circuit comprises a distilled water storage tank
configured to receive a
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distilled water output stream from the regenerator and store the distilled
water for delivery to
the evaporative cooler as needed for make up water.
[00167] Example 44 provides the system of any of Examples 29-43 optionally
configured
such that the energy gain of the desiccant between the LAMEE inlet and outlet
results in a
temperature of the desiccant at an outlet of the LAMEE being higher than a
temperature of the
desiccant at an inlet of the LAMEE.
[00168] Example 45 provides the system of any of Examples 29-44 optionally
configured
such that the desiccant dryer LAMEE is a first LAMEE and the evaporative
cooler is a second
LAMEE.
[00169] Example 46 provides a method of conditioning air for an enclosed
space, and the
method can include directing air through a process plenum having a plenum
inlet and outlet,
directing the air through a liquid-to-air energy exchanger (LAMEE) arranged
inside the plenum,
and directing a desiccant through the LAMEE, the desiccant and air separated
by a membrane of
the LAMEE. The method can also include transferring energy in the LAMEE from
the desiccant
to the air, an energy reduction of the air between a LAMEE inlet and outlet
being about equal to
an energy gain of the desiccant between the LAMEE inlet and outlet.
Transferring energy in the
LAMEE can include removing water from the air using the desiccant. A first
concentration of
water in the desiccant can be lower at a LAMEE inlet compared to a second
concentration of
water in the desiccant at a LAMEE outlet, and the desiccant at the LAMEE
outlet can be a dilute
desiccant. The method can also include regenerating a portion of the dilute
desiccant in a
regenerator to separate the water from the desiccant, directing a concentrated
desiccant exiting
the regenerator to a fluid circuit for the desiccant dryer LAMEE, and
directing distilled water
from the regenerator to one or more evaporative coolers in the conditioning
system.
[00170] Example 47 provides the method of Example 46 optionally configured
such that
directing the concentrated desiccant exiting the regenerator to a fluid
circuit for the desiccant
dryer LAMEE includes transporting the concentrated desiccant to a mixing tank
that receives
the dilute desiccant from the LAMEE outlet
[00171] Example 48 provides the method of Example 47 optionally further
comprising
directing a first portion of the dilute desiccant from the LAMEE outlet to the
mixing tank and
directing a second portion of the dilute desiccant from the LAMEE outlet to
the regenerator.
[00172] Example 49 provides the method of Example 48 optionally configured
such that the
first portion is greater than the second portion.
[00173] Example 50 provides the method of Example 48 or 49 optionally further
comprising
regulating and varying the first and second portions.
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[00174] Example 51 provides the method of any of Examples 47-50 optionally
further
comprising directing the concentrated desiccant to a concentrated desiccant
storage tank prior
to transporting the concentrated desiccant to the mixing tank.
[00175] Example 52 provides the method of Example 47 optionally further
comprising
mixing the dilute desiccant and the concentrated desiccant in the mixing tank
to form a mixed
desiccant having a concentration of desiccant higher than a concentration of
the dilute desiccant
and lower than a concentration of the concentrated desiccant.
[00176] Example 53 provides the method of Example 52 optionally configured
such that
regenerating a portion of the dilute desiccant includes transporting a first
portion of the mixed
desiccant to the LAMEE and transporting a second portion of the mixed
desiccant to the
regenerator.
[00177] Example 54 provides the method of Example 53 optionally further
comprising
regulating a volume of the second portion of the mixed desiccant transported
to the regenerator
relative to a volume of the first portion of the mixed desiccant transported
to the LAMEE.
[00178] Example 55 provides the method of Example 54 optionally configured
such that
regulating the volume of the second portion of the mixed desiccant transported
to the
regenerator comprises transporting less than 25 percent by volume of the mixed
desiccant
exiting the tank to the regenerator.
[00179] Example 56 provides the method of any of Examples 46-55 optionally
configured
such that the one or more evaporative coolers comprises an evaporative cooler
arranged in the
plenum downstream of the desiccant dryer LAMEE.
[00180] Example 57 provides the method of Example 56 optionally configured
such that the
desiccant dryer LAMEE is a first LAMEE and the evaporative cooler downstream
is a second
LAMEE.
[00181] Example 58 provides the method of Example 56 or 57 optionally further
comprising
using the distilled water from the regenerator as make up water for operation
of the
evaporative cooler.
[00182] Example 59 provides the method of any of Examples 56-58 optionally
configured
such that directing air through a process plenum includes directing scavenger
air through a first
plenum. The method can also include directing process air through a second
plenum, the
process air coming from an enclosed space at an increased-temperature, the
second plenum
configured to cool the process air for delivery back to the enclosed space at
a reduced-
temperature.
[00183] Example 60 provides the method of Example 59 optionally further
comprising
delivering reduced-temperature water exiting the evaporative cooler to an LAHX
arranged in
the second plenum to cool the process air being directed through the second
plenum.
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[00184] Example 61 provides a system for conditioning air for an enclosed
space and the
system can comprise a plurality of conditioning units. Each conditioning unit
can comprise a
liquid-to-air membrane energy exchanger (LAMEE) arranged inside a plenum
configured to
pass an air stream there through and an evaporative cooling component arranged
inside the
plenum downstream of the LAMEE. The LAMEE can comprise a desiccant flow path
separated
from the air flow path by a membrane. The LAMEE can be configured to circulate
a desiccant
through the desiccant flow path and remove water from the air stream, a
concentration of water
in the desiccant at a LAMEE outlet being higher than a concentration of water
in the desiccant at
a LAMEE inlet The system can further comprise a regeneration system in fluid
connection with
the LAMEE outlet of each conditioning unit, the regeneration system having a
regeneration inlet
configured to receive a dilute desiccant stream, the regeneration system
configured to separate
water from desiccant in the dilute desiccant stream, the regeneration system
having a first
outlet for discharging a concentrated desiccant stream and a second outlet for
discharging a
distilled water stream. The system can further comprise a concentrated
desiccant storage
system configured to receive and store the concentrated desiccant stream from
the regenerator
system, the concentrated desiccant storage system supplying concentrated
desiccant to each
conditioning unit as needed for operation of the LAMEE of each conditioning
unit. The system
can further comprise a distilled water storage system configured to receive
and store the
distilled water stream from the regenerator system, the distilled water
storage system
supplying water to the evaporative cooling component of each conditioning unit
as needed for
operation of the evaporative cooling component.
[00185] Example 62 provides the system of Example 61 optionally configured
such that each
conditioning unit further comprises a mixing tank configured to receive the
concentrated
desiccant from the concentrated desiccant storage system and a dilute
desiccant from the
LAMEE outlet.
[00186] Example 63 provides the system of Example 62 optionally configured
such that a
first portion of a desiccant output stream from the mixing tank of each
conditioning unit is
transported back to the LAMEE inlet for recirculation and a second portion of
the desiccant
output stream from the mixing tank of each conditioning unit is transported to
the regeneration
system.
[00187] Example 64 provides the system of Example 63 optionally configured
such that a
volume of the first portion is greater than a volume of the second portion.
[00188] Example 65 provides the system of any of Examples 61-64 optionally
configured
such that the enclosed space is a data center.
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[00189] Example 66 provides the system of any of Examples 61-65 optionally
configured
such that each conditioning unit receives process air from the enclosed space
at an increased-
temperature and delivers the process air back to the enclosed space at a
reduced-temperature.
[00190] Example 67 provides the system of any of Examples 61-66 optionally
further
comprising an external source of treated water for delivery to the
conditioning units as needed
for backup.
[00191] Example 68 provides the system of any of Examples 61-67 optionally
configured
such that the LAMEE of each conditioning unit is a first LAMEE and the
evaporative cooling
component of each conditioning unit is a second LAMEE.
[00192] Example 69 provides the system of Example 68 optionally configured
such that the
plenum of each conditioning unit is a first plenum and each conditioning unit
further comprises
a second plenum configured to pass a process air stream there through. The
second LAMEE can
produce reduced-temperature water and the reduced temperature water can be
transported to
the second plenum to cool process air in the process air stream.
[00193] Example 70 provides a system or method of any one or any combination
of
Examples 1-69, which can be optionally configured such that all steps or
elements recited are
available to use or select from.
[00194] Various aspects of the disclosure have been described. These and other
aspects are
within the scope of the following claims.
38
