Note: Descriptions are shown in the official language in which they were submitted.
MULTI-STAGE SYSTEM FOR COOLING A REFRIGERANT
IECHNICAL FIELD
Certain embodiments of the present disclosure relate, in general, to a multi-
stage system
for cooling a refrigerant.
BACKGROUND
Air conditioners provide cool air by evaporating cool liquid refrigerant. Cool
refrigerant is
provided to evaporators by condensers, during operation. The temperature of
the cool liquid
refrigerant provided by the condenser is dependent on the ambient temperature.
The condensers
condense hot gaseous refrigerant delivered from a compressor to a cooler
liquid refrigerant. A
condenser fan may blow air on the hot gaseous refrigerant to remove heat from
the gaseous
refrigerant.
Refrigeration systems are similar to air conditioners in the sense that both
systems supply
cool refrigerant to an evaporator in order to cool a space. As examples, the
space being cooled
may be a home or other building in the case of an air conditioner, or a
refrigerated case or freezer
in the case of a refrigeration system. Refrigerant discharged from the
evaporator is compressed
and cooled so that the refrigerant can again be circulated to the evaporator
for continued cooling.
SUMMARY
In certain implementations, a refrigeration system comprises first and second
evaporators,
first and second compressors, and a gas cooler. The first and second
evaporators receive liquid
refrigerant from a flash tank and evaporate the refrigerant to cool a first
case and a second case,
respectively. The second case has a higher temperature set point than the
first case. The first
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compressor compresses the refrigerant discharged from the first evaporator.
The second
compressor compresses the refrigerant discharged from the first compressor,
the flash gas from
the flash tank, and the refrigerant discharged from the second evaporator. The
gas cooler
comprises an air-cooled stage that cools the refrigerant discharged from the
second compressor
and an evaporative stage that cools the refrigerant discharged from the air-
cooled stage. The gas
cooler further comprises an outlet that supplies the cooled refrigerant to the
flash tank through an
expansion valve.
In various implementations, a system may include an auxiliary heat exchanger.
The
auxiliary heat exchanger may include a first surface and an opposing second
surface. Fluid
retention member(s) may be coupled to at least a portion of the first surface
and/or a refrigerant
conduit may be coupled to at least a portion of the second surface. A
temperature of at least a
part of the refrigerant in the refrigerant conduit may be reduced by heat
transfer from the
refrigerant to at least one of the fluid retention members.
Implementations may include one or more of the following features. The
auxiliary heat
exchanger may include a condensate line coupled to at least one of the fluid
retention members.
The auxiliary heat exchanger may include a container coupled to at least one
of an evaporator or
a water line. A fluid leaving the container may flow to at least one of the
fluid retention
members. The container may automatically allow water to flow from the water
line into the
container when a fluid level in the container is less than a predeteimined
fluid level. The system
may include an air conditioner that includes a switch. The switch may control
the operation of
the auxiliary heat exchanger. The auxiliary heat exchanger reduces a
temperature of at least a
portion of the refrigerant leaving a condenser of the air conditioner. At
least one of the fluid
retention members may include channels. The channels may retain fluid at least
partially in the
channels. Air may flow proximate the channels and at least partially evaporate
the fluid at least
partially retained in the channels to reduce a temperature of at least a part
of the refrigerant.
In various implementations, a system may include an auxiliary heat exchanger.
The
auxiliary heat exchanger may include a first surface and a second opposing
surface. The
auxiliary heat exchanger may include thermoelectric cooler(s) coupled to at
least a portion of the
first surface of the auxiliary heat exchanger and/or a refrigerant conduit
coupled to at least a
portion of the second surface of the auxiliary heat exchanger. A temperature
of at least a part of
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the refrigerant in the refrigerant conduit may be reduced by heat transfer to
at least one of the
thermoelectric coolers.
Implementations may include one or more of the following features. A
temperature of a
refrigerant leaving the auxiliary heat exchanger may be less than
approximately 3 F. above an
ambient temperature. The auxiliary heat exchanger may include an air inlet and
an air outlet. At
least a portion of the air from the condenser blower may flow through the air
inlet to the air
outlet. A portion of the air may remove heat from at least one of the
thermoelectric coolers. The
system may include an air conditioner and the air conditioner may include the
auxiliary heat
exchanger. The auxiliary heat exchanger may reduce a temperature of at least a
portion of the
refrigerant leaving the condenser of the air conditioner. The auxiliary heat
exchanger may be at
least partially coupled to the condenser of the air conditioner. The auxiliary
heat exchanger may
include a converter to convert alternating current to direct current. The
converter may provide
direct current to at least one of the thermoelectric coolers. The system may
be a retrofit kit to
couple to an air conditioner.
Various implementations may include providing refrigerant to a condenser of an
air
conditioner and condensing the refrigerant to a liquid at a first temperature
using the condenser.
A determination may be made whether a request to operate the auxiliary heater
has been
received. If the request for operation of the auxiliary heat exchanger has
been received: the liquid
refrigerant may be provided at the first temperature to the auxiliary heat
exchanger; the auxiliary
heat exchanger may be allowed to reduce the temperature of the refrigerant in
the auxiliary heat
exchanger to a second temperature; and at least a portion of the refrigerant
may be provided at
the second temperature to the evaporator.
Implementations may include one or more of the following features. Allowing
the
auxiliary heat exchanger to reduce the temperature of the refrigerant in the
auxiliary heat
exchanger to a second temperature may include: allowing a fluid to flow to one
or more fluid
retention members at least partially coupled to a first surface of the
auxiliary heat exchanger;
allowing the refrigerant to flow through a refrigerant conduit at least
partially coupled to a
second surface of the auxiliary heat exchanger; and/or allowing heat to
transfer between the
refrigerant in the refrigerant conduit and at least one of the fluid retention
members. A
temperature of the refrigerant may be reduced to the second temperature by the
heat transfer
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from the refrigerant to at least one of the fluid retention members. The
second surface may be
opposed to the first surface of the auxiliary heat exchanger. Condensate from
the evaporator of
the air conditioner may be allowed to flow into a container. A determination
may be made
whether to allow water from a water line to flow into the container. The water
may be allowed to
flow into the container if the deteimination is made to allow water from the
water line to flow
into the container. A fluid may be allowed to flow from the container to at
least one of the fluid
retention members.
Allowing the auxiliary heat exchanger to reduce the temperature of the
refrigerant in the
auxiliary heat exchanger to a second temperature may include: allowing one or
more
thermoelectric coolers at least partially coupled to a first surface of the
auxiliary heat exchanger
to operate; allowing the refrigerant to flow through a refrigerant conduit at
least partially coupled
to a second surface of the auxiliary heat exchanger; and allowing heat to
transfer between the
refrigerant and at least one of the thermoelectric coolers. A temperature of
at least a part of the
refrigerant in the refrigerant conduit may be reduced to a second temperature
by the heat transfer
.. from the refrigerant to at least one of the thermoelectric coolers. At
least a portion of the liquid
refrigerant at the first temperature may be provided to an evaporator of the
air conditioner, if the
request to operate the auxiliary heater has not been received. When the
request to operate the
auxiliary heater has been received, a temperature of the refrigerant may be
reduced to a second
temperature that may be less than approximately 3 F. above an ambient
temperature. The air
conditioner may include a default setting to request operation of the
auxiliary heat exchanger.
The details of one or more implementations are set forth in the accompanying
drawings
and the description below. Certain embodiments may have one or more technical
advantages. As
an example, certain embodiments may provide a two-stage gas cooler comprising
an air-cooled
stage and an evaporative stage. The two-stage gas cooler may provide water
savings compared
to a gas cooler that uses only evaporative type cooling. The two-stage gas
cooler may consume
less energy compared to a gas cooler that uses only air-cooled type cooling.
The two-stage gas
cooler may be particularly well-suited to hot and dry climates that would
otherwise require a lot
of energy and/or water to cool refrigerant. Certain embodiments may have all,
some, or none of
these advantages. Other features, objects, and advantages of the
implementations will be
apparent from the description and drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of this disclosure and its features,
reference is now
made to the following description, taken in conjunction with the accompanying
drawings, in
which:
FIG. 1 illustrates an implementation of an example of an air conditioner.
FIG. 2A illustrates a cross-sectional view of an implementation of an example
auxiliary
heat exchanger.
FIG. 2B illustrates a cross-sectional view of an implementation of an example
auxiliary
heat exchanger.
FIG. 3 illustrates a perspective view of an implementation of an example
auxiliary heat
exchanger.
FIG. 4 illustrates a cross-sectional view of an implementation of a portion of
an example
auxiliary heat exchanger.
FIG. 5 illustrates a perspective view of an implementation of an example
auxiliary heat
exchanger.
FIG. 6 illustrates an implementation of an example process for operation of an
air
conditioner.
FIG. 7 illustrates an implementation of a portion of an example air
conditioner.
FIG. 8 illustrates an implementation of an example process for operation of an
auxiliary
heat exchanger.
FIG. 9 illustrates an implementation of a portion of an example air
conditioner.
FIG. 10 illustrates an implementation of an example process for operation of
an auxiliary
heat exchanger.
FIG. I 1 illustrates an implementation of an example refrigeration system
comprising a
multi-stage cooler.
FIG. 12 illustrates an implementation of an example refrigeration system
comprising a
multi-stage cooler.
FIG. 13 illustrates an example of a method cooling a refrigerant using a multi-
stage
system.
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FIG. 14 illustrates an example of enthalpy of a refrigeration system that uses
multi-stage
cooling.
Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION
In various implementations, the temperature of refrigerant in an air
conditioner may be
reduced using an auxiliary heat exchanger. For example, an auxiliary heat
exchanger may reduce
the temperature of refrigerant exiting a condenser of the air conditioner
using fluid retention
member(s), thermoelectric cooler(s), and/or other appropriate heat
exchanger(s).
FIG. 1 illustrates an implementation of an example air conditioner 100. The
air
conditioner 100 may include components such as an evaporator 105, evaporator
fan 110,
compressor 115, condenser 120, condenser fan 125, and auxiliary heat exchanger
130. The air
conditioner 100 may include a theimal expansion valve (not shown) and/or
control system (not
shown) to manage operations of the air conditioner. One or more of the
components may be
.. coupled through refrigerant lines 135 (e.g., conduit between components at
least partially
containing refrigerant during use). During use, the evaporator 105 allows
liquid refrigerant (e.g.,
R-22 and/or R-410A) to evaporate to form a gaseous refrigerant that is
provided to the
compressor 115. At least a portion of the air from the evaporator fan 110 may
flow at least
partially through the evaporator 105 and the cooler air exiting the evaporator
may be provided
(e.g., via ducting) to a location.
The compressor 115 may increase the pressure of the gaseous refrigerant and
the higher
pressure gas is provided to the condenser 120. The condenser 120 allows at
least a portion of the
gaseous refrigerant to condense into a liquid. At least a portion of the air
from the condenser fan
125 may flow at least partially through the condenser 120 and absorb heat from
the refrigerant,
which may allow at least portions of the gaseous refrigerant to liquefy.
At least a portion of the liquid refrigerant from the condenser 120 may be
allowed to flow
to the auxiliary heat exchanger 130. For example, the air conditioner 100 may
include a switch
140 that allows fluid flow (e.g., at least a part of the refrigerant from the
condenser and/or at
least a part of the air from the condenser fan) to be directed to and/or
bypass the auxiliary heat
.. exchanger 130. A controller (e.g., a computer) may determine whether to
allow fluid flow to the
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auxiliary heat exchanger 130. For example, a controller may respond to a user
request for
operation of the auxiliary heat exchanger 130. In some implementation, a
controller may
determine whether to operate the auxiliary heat exchanger 130 based on a
request from a user
(e.g., when cooling is requested by a user during high ambient temperatures,
such as above 85
F.). An air conditioner may include a default setting, such as to allow
operation of the auxiliary
heat exchanger 130 and/or to restrict operation of the air conditioner without
use of the auxiliary
heat exchanger. In some implementations, at least a part of the refrigerant
may bypass the
auxiliary heat exchanger and flow to the evaporator. In some implementations,
the air
conditioner 100 may include a metering device (not shown), such as a thermal
expansion valve.
The liquid refrigerant may be allowed to at least partially pass from the
auxiliary heat exchanger
130 and/or condenser 120 through the thermal expansion valve. The thermal
expansion valve
may allow and/or restrict fluid flow through the valve at least partially
based on the automatic
adjustment of the thermal expansion valve and/or the control system.
The auxiliary heat exchanger 130 may reduce the temperature of at least a part
of the
refrigerant from the condenser 120. When the refrigerant leaves the auxiliary
heat exchanger
130, the refrigerant may be at an exit temperature less than a predetermined
temperature. For
example, the exit temperature of the refrigerant may be: less than
approximately one degree
Fahrenheit above ambient temperature (e.g., Ambient temperature+approximately
1 F.); and/or
less than approximately three degrees Fahrenheit above ambient temperature
(e.g., Ambient
temperature+approximately 3 F.). The exit temperature of the refrigerant may
be less than or
approximately equal to ambient temperature.
Ambient temperature may be a temperature proximate at least a portion of the
auxiliary
heat exchanger 130, the condenser 120, and/or the condenser fan 125 (e.g.,
ambient temperature
may be a temperature proximate an opening of an auxiliary heat exchanger). A
sensor may be
positioned proximate =the condenser 120 and a controller may be coupled to the
sensor to
determine the ambient temperature.
By reducing the temperature of the refrigerant entering the evaporator 105,
the capacity
of the evaporator may be increased. When the capacity of the evaporator 105 is
increased, the
EER (energy efficiency ratio) may be increased. For example, since the
temperature of the
refrigerant is cooler (e.g., than in a system without an auxiliary heat
exchanger), more heat may
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be transferred from air proximate the evaporator 105 and thus, more cool air
can be provided to a
location in response to a user request. The boost in capacity of the
evaporator 105 may allow an
air conditioner to operate more effectively (e.g., more responsive to a user
request, be able to
provide cooler air, and/or operation may be less likely to cause mechanical
failure). An air
conditioner with an auxiliary heat exchanger may have a higher EER rating than
a similar air
conditioner without an auxiliary heat exchanger (e.g., an air conditioner with
at least some
similarly sized components) because the cooling capacity of the air
conditioner may be increased
with little and/or no increase in energy use, in some implementations.
In some implementations, auxiliary heat exchanger 130 may be similar to the
condenser
120. For example, the auxiliary heat exchanger 130 may be a heat exchanger
similar to and
smaller in scale (e.g., in output capabilities) than the condenser 120. For
example, the auxiliary
heat exchanger 130 may include a second refrigerant that cools the refrigerant
from the
condenser 120. The second refrigerant may be the same and/or different from
the refrigerant
from the condenser 120. Mixing between the refrigerant from the condenser 120
and the second
refrigerant may be inhibited. A second compressor of the auxiliary heat
exchanger 130 may
compress the second refrigerant. The compressor of the auxiliary heat
exchanger 130 may be
separate from the compressor 120 of the air conditioner. The compressed second
refrigerant may
be allowed to flow to a second condenser (e.g., a second condenser unit and/or
a portion of the
condenser of the air conditioner) to cool the first refrigerant (e.g., the
refrigerant flowing from
the condenser 120 to the evaporator 105 of the air conditioner 100).
In some implementations, the auxiliary heat exchanger 130 may include
components,
such as fluid retention member(s) and/or thermoelectric cooler(s). FIG. 2A
illustrates a cross-
sectional view of an implementation of an example of an auxiliary heat
exchanger 200. FIG. 213
illustrates a cross-sectional view of an implementation of an example
auxiliary heat exchanger
250. FIG. 3 illustrates a perspective view of an implementation of an example
of an auxiliary
heat exchanger 200.
The auxiliary heat exchanger may include a housing. The housing may include
thermally
conductive material. The auxiliary heat exchanger and/or housing may have a
cross-sectional
shape similar to a circle, oval, line, c-shaped, and/or any other appropriate
shape. For example,
as illustrated in FIGS. 2A and 3, a housing 202 of the auxiliary heat
exchanger 200 may have a
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rectangular cross-sectional shape. The auxiliary heat exchanger may be
tubular. As illustrated in
FIG. 2B, a housing 252 of the auxiliary heat exchanger 250 may be a plate
(e.g., with planar
and/or curved sections). In some implementations, the auxiliary heat exchanger
may include two
plates (e.g., with planar and/or curved sections) and an opening disposed
between the plates. In
some implementations, a shape of an auxiliary heat exchanger may be selected
to control air
flow. For example, as illustrated in FIGS. 2A and 3, the rectangular cross-
sectional shape of the
housing 202 may restrict airflow to the opening 245 disposed in the housing.
As illustrated in FIGS. 2A, 2B, and 3, the auxiliary heat exchanger 200, 250
may include
two opposing surfaces, a first surface 205 and a second surface 210. For
example, as illustrated
in FIGS. 2A and 3, the first surface 205 may be at least a portion of an inner
surface of the
auxiliary heat exchanger 200 and/or the second surface 210 may be at least a
portion of the outer
surface of the auxiliary heat exchanger. As illustrated in FIG. 2B, the first
surface 205 and the
second surface 210 may be opposing sides of a plate (e.g., a plate with curved
and/or planar
portions) of the auxiliary heat exchanger 250.
The auxiliary heat exchanger 200, 250 may include a refrigerant line 215
disposed
proximate the second surface 210. The refrigerant line 215 may be coupled to
at least a portion
of the second surface 210. For example, the refrigerant line 215 may be
coupled to at least a
portion of the second surface 210 using clips, soldering, brazing, and/or
welding. The refrigerant
line 215 may include a refrigerant inlet 220 and a refrigerant outlet 225.
The auxiliary heat exchanger 200, 250 may include fluid retention member(s)
230
disposed proximate the first surface 205. The fluid retention member(s) 230
may be coupled to at
least a portion of the first surface 205. The fluid retention member 230 may
be glued to a portion
of the first surface 205, for example. In some implementations, the fluid
retention member 230
may be a portion of and/or integrated with the first surface 205 of the
auxiliary heat exchanger
200, 250.
As illustrated in FIGS. 2A and 3, the auxiliary heat exchanger 200 may include
an air
inlet 235 and an air outlet 240. Air may flow at least partially through an
opening 245 disposed
between the opposing first surfaces 205. The air flow may be generated by the
condenser fan.
For example. a portion of the air flow generated by the condenser fan may be
directed to the
auxiliary heat exchanger 200. The air flow may enter the auxiliary heat
exchanger 200 at and/or
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proximate to the air inlet 235 and leave the auxiliary heat exchanger at
and/or proximate to the
air outlet 240.
As illustrated in FIGS. 2A and 3 the air flow (e.g., from a condenser fan)
through the
opening 245 of the auxiliary heat exchanger 200 may remove heat (e.g., from
the first surface
205 and/or a fluid retention member 230) As illustrated in FIG. 2B, air (e.g.,
from a condenser
fan) may flow proximate a surface of the fluid retention member 230. A fluid,
such as water
from condensate and/or a water line, may be disposed and/or retained at least
partially on the
fluid retention member 230. The water may have a lower temperature than the
refrigerant in the
refrigerant line 215. Heat from the refrigerant may be transferred to the
refrigerant conduit 215.
The heat from the refrigerant conduit 215 may be transferred through a housing
202, 252 of the
auxiliary heat exchanger 200, 250 to fluid retention member(s) 230. The heat
from a fluid
retention member 230 may be transferred to the fluid at least partially
retained by the fluid
retention member. As the air flow proximate the fluid retention member 230, at
least a portion of
the fluid in the fluid retention member may evaporate. The fluid may evaporate
due to the heat
transfer from refrigerant, refrigerant conduit 215, housing 202, 252, fluid
retention member 230,
and/or air flow. Approximately 1000 BTUs of energy may be absorbed by
evaporation of each
pound of the fluid (e.g., water) and so, heat may be removed from the
refrigerant and the
temperature of the refrigerant may be reduced.
In some implementations, as illustrated in FIGS. 2A, 2B, and 3, the first
surface 205 may
be cooled (e.g., a temperature may be reduced) by the evaporation of the fluid
at least partially
retained by the fluid retention member(s) 230. The cooling of the first
surface 205 may cool the
second surface 210, the housing 202, 252, the refrigerant conduit 215, and/or
the refrigerant.
Thus, the evaporation of fluid from the fluid retention members 230 may cool
and/or reduce the
temperature of the refrigerant.
In some implementations, the fluid retention members 230 may at least
partially absorb
fluid and/or at least partially retain fluid. The fluid retention member 230
may retain fluid for a
period of time and then allow fluid to flow from the fluid retention member.
For example, the
fluid retention member 230 may retain a fluid and allow the fluid to evaporate
from the fluid
retention member.
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The fluid retention members 230 may include an absorbent pad (e.g., a cloth),
a coated
member, a plate with bristles, fins, channels, tubing, and/or a flocked plate.
For example, a
flocked plate may include a plate with fibers coupled in a normal direction to
the plate. FIG. 4
illustrates an implementation of a portion 400 of an auxiliary heat exchanger.
As illustrated, the
fluid retention member 405 includes flocking 410. The flocking 410 may include
fibers 415. The
fibers 415 may be coupled to the plate 420 such that the fibers are normal to
the plate. The fibers
415 may retain fluid in and/or within the fluid retention member 405. The
flocking 410 may
include polyester fibers coupled to a surface of the fluid retention member
405, as an example. In
some implementations, the fluid retention member 405 may include channels
(e.g., disposed
between fibers 415 and/or formed in the fluid retention members) and/or
recesses to at least
partially retain (e.g., temporarily retain and/or retain a portion of) the
fluid).
The fluid retention member 405 may be coupled to a portion of the first
surface 425 of
the auxiliary heat exchanger. In some implementations, the fluid retention
member 405 may be a
portion of and/or formed in the first surface 425 of the auxiliary heat
exchanger. The fluid
retention member 405 may be glued to a first surface 425 of the auxiliary heat
exchanger 405, for
example. In some implementations, the fibers 415 may be glued directly to the
first surface 425
of the auxiliary heat exchanger.
The auxiliary heat exchanger may include a conduit 430 coupled to a
distributer 435 to
deliver a fluid to the fluid retention member 405. The distributer 435 may
include a plurality of
openings 440. During use, a fluid, such as water (e.g., from condensate and/or
water from a
water line), may be delivered to the auxiliary heat exchanger via the conduit
430. The distributer
435 may deliver fluid from the conduit 430 to the fluid retention member 405.
The openings 440
may provide the fluid across a surface of the fluid retention member 405. For
example, the fluid
may flow from the openings 440 and be at least partially retained by the
fibers 415 and/or
channels of the fluid retention member 405.
Various implementations of auxiliary heat exchangers have been described as
including a
housing to which fluid retention members and/or refrigerant conduit are
coupled, as examples. In
some implementations, the fluid retention member may be directly coupled to a
refrigerant
conduit such that a first surface and a second surface are surfaces of the
refrigerant conduit. In
some implementations, the refrigerant conduit may be coupled to a portion of
the fluid retention
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member (e.g., a plate of the fluid retention member). In some implementations,
the fluid
retention member may include flocked vertical fins proximate a refrigerant
conduit.
In some implementations, the auxiliary heat exchanger may include
thermoelectric
cooler(s). FIG. 5 illustrates an implementation of an example auxiliary heat
exchanger 500
comprising a thermoelectric cooler 510. The auxiliary heat exchanger 500 may
include a housing
502, such as a plate. The thermoelectric cooler 510 may be disposed in an
auxiliary heat
exchanger similarly to a fluid retention member. The thermoelectric cooler 510
may be coupled
to at least a portion of the first surface 205 of the housing 502 of the
auxiliary heat exchanger
500 and the refrigerant line 215 may be coupled at least partially to the
second surface 210 of the
housing 502. In some implementations, the thermoelectric cooler 510 may
include a portion
configured to couple to a portion of the condenser (e.g., a portion of the
condenser may function
as the auxiliary heat exchanger and reduce the temperature of the refrigerant
lower than the
condenser could without the auxiliary heat exchanger). For example, a heat
resistant coupling
may be included on a surface of the thermoelectric cooler 510 to affix the
thermoelectric cooler
to a part of the condenser.
The thermoelectric cooler may include any appropriate thermoelectric cooler,
such as a
thermoelectric cooler commercially available from Marlow Industries (Dallas,
Tex.) and/or
devices that utilize Peltier effects. The thermoelectric cooler may be coupled
to a battery or other
power source (e.g., through wires 525 coupled to the thermoelectric cooler).
In some
implementations, a converter (e.g., AC to DC) may be coupled to the
thermoelectric cooler so
that the thermoelectric cooler may operate using the same power source as the
air conditioner.
The thermoelectric cooler 510 may include opposing hot 515 and cold 520 sides.
For
example, during use the thermoelectric cooler 510 may generate a cold side 520
and a hot side
515. The temperature of the cold side 520 may be less than a temperature of
the hot side 515.
The cold side 520 of the thermoelectric cooler may be coupled to the first
surface 205 of the
housing 502 of the auxiliary heat exchanger 500 and the refrigerant line 215
may be coupled to
the second surface 210 of the housing 502 of the auxiliary heat exchanger 500.
During use, heat
may transfer from the refrigerant in the refrigerant line 215, to the housing
502, and/or to the
cold side 520 of the thermoelectric cooler 510. Air from a condenser fan may
direct air towards
the hot side 515 of the thermoelectric cooler and/or remove heat from the hot
side. Thus, the
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temperature of the refrigerant may be reduced by the thermoelectric cooler, in
some
implementations.
FIG. 6 illustrates an implementation of an example process 600 for operation
of an air
conditioner. A request for operation of an air conditioner may be received
(operation 605). For
example, a user may request that cold air be delivered to a location.
A gaseous refrigerant may be provided to a condenser (operation 610). During
operation
of the air conditioner, refrigerant may provide cool air to a location using
the evaporator and
ducting to a location (e.g., cool air provided by the evaporator and
evaporator blower may be
transported to the location using the ducting). The refrigerant may leave the
evaporator as a gas,
be at least partially compressed, and provided to the condenser.
The refrigerant may be at least partially condensed to a liquid refrigerant at
a first
temperature (operation 615). For example, the condenser may condense the
gaseous refrigerant
that has been compressed. The liquid refrigerant leaving the condenser may be
at a first
temperature. Since the heat exchange in the condenser is between the air at
ambient temperature
.. and the refrigerant, the temperature to which the refrigerant can be
lowered may be restricted by
the temperature of the air. The first temperature may be, for example, at
least ten degrees
Fahrenheit greater than ambient temperature (e.g., 10 F.+Ambient
temperature).
Whether a request to operate the auxiliary heat exchanger has been received
may be
determined (operation 620). For example, the controller of an air conditioner
may monitor
.. ambient temperatures and automatically allow the auxiliary heat exchanger
to operate during a
predetermined temperature range (e.g., temperatures greater than 82 F.,
temperatures greater
than 116 F.). As another example, a default setting of an air conditioner may
include a request
that an auxiliary heat exchanger operation be allowed and/or restricted. In
some
implementations, a user may request operation of the auxiliary heat exchanger.
At least a part of the refrigerant at the first temperature may be provided to
the evaporator
of the air conditioner, if a determination has been made that a request to
operate the auxiliary
heat exchanger has not been received (operation 625). For example, the
auxiliary heat exchanger
may be bypassed and the refrigerant may flow from the condenser to an
expansion valve and/or
evaporator. In some implementations, the auxiliary heat exchanger may be
turned off or remain
off when the request to operate the auxiliary heat exchanger has not been
received. For example,
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the air flow to the auxiliary heat exchanger may be turned off, and/or water
flow from the
condensate and/or other source may be restricted. Thus, even though the
refrigerant at the first
temperature flows through the auxiliary heat exchanger, the auxiliary heat
exchanger does not
substantially lower the temperature of the refrigerant.
In some implementations, operation of an auxiliary heat exchanger may be not
requested
and/or the auxiliary heat exchanger may be bypassed. For example, to increase
the length of a
cooling cycle, the operation of the auxiliary heat exchanger may be
restricted. For example,
when the auxiliary heat exchanger is used in conjunction with the condenser on
cold days (e.g.,
65 degrees Fahrenheit), the air conditioner may quickly reach a temperature
requested by the
user and quickly cycle on and off. The quick cycle (e.g., short and repetitive
cycles) may stress
the air conditioner and/or may lead to premature mechanical failure of the air
conditioner. Thus,
an auxiliary heat exchanger may be bypassed and the air conditioner may
operate for longer
cycles (e.g., compared to operations using the auxiliary heat exchanger) using
the condenser and
restricting use of the auxiliary heat exchanger (e.g., bypass the auxiliary
heat exchanger).
At least a part of the liquid refrigerant at the first temperature may be
provided to the
auxiliary heat exchanger, if a determination has been made that a request to
operate the auxiliary
heat exchanger was received (operation 630). For example, a user may request
operation of the
auxiliary heat exchanger. When temperatures are high (e.g., greater than 82
F.), the auxiliary
heat exchanger may allow the evaporator to have a greater capacity (e.g.,
because a temperature
of the refrigerant provided to the evaporator is lower than the temperature of
the refrigerant
exiting the condenser) when compared to a similar air conditioner without an
auxiliary heat
exchanger (e.g., an air conditioner with one or more similarly sized
components, such as a
condenser).
The auxiliary heat exchanger may be allowed to reduce the temperature of the
liquid
refrigerant to a second temperature (operation 635). Since heat is transferred
between a cold zone
in the auxiliary heat exchanger and the refrigerant, a lower temperature may
be obtained in the
refrigerant (e.g., when compared with the refrigerant temperature exiting the
condenser and/or
when use of the auxiliary heat exchanger is restricted). For example, the
auxiliary heat exchanger
may be allowed to reduce the temperature of the liquid refrigerant to a
temperature
approximately equal to and/or less than ambient temperature (e.g., a
temperature proximate at
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least a portion of the condenser). The temperature of the refrigerant leaving
the auxiliary heat
exchanger may be less than or approximately equal to 3 F. more than ambient
temperature. In
some implementations, the auxiliary heat exchanger may reduce the temperature
of the
refrigerant by a predetermined amount (e.g., reduce the temperature
approximately 3 F., 5 F.,
and/or 10 F.). The auxiliary heat exchanger may reduce the temperature of the
refrigerant to
approximately equal to ambient temperature or less than ambient temperature,
in some
implementations.
A cold zone may be generated proximate a surface of an auxiliary heat
exchanger using a
thermoelectric cooler and/or a fluid retention member (operation 640). For
example, a
thermoelectric cooler and/or fluid retention member may be coupled to a
surface of the auxiliary
heat exchanger. The thermoelectric cooler and/or fluid retention member may be
allowed to
operate such that the surface of the auxiliary heat exchanger proximate the
thermoelectric cooler
and/or fluid retention member (e.g., first surface) is colder than ambient
temperature. Thus, heat
from the refrigerant may be transferred to the cold zone and/or removed from
the cold zone, in
some implementations. When a thermoelectric cooler is used, the air flows
across the hot side
and may allow the thermoelectric cooler to continue to operate properly (e.g.,
inhibit
overheating). The refrigerant may leave the auxiliary heat exchanger (e.g.,
via the refrigerant line
outlet) at a second temperature. The second temperature may be less than the
temperature that at
which the refrigerant entered the auxiliary heat exchanger (e.g., via the
inlet of the refrigerant
line).
At least a part of the liquid refrigerant at the second temperature may be
provided to the
evaporator of the air conditioner (operation 640). For example, the liquid
refrigerant may flow
from the auxiliary heat exchanger to the evaporator. In some implementations,
a thermal
expansion valve may be included to control flow of the refrigerant to the
evaporator. The thermal
expansion valve may be disposed on a refrigerant line such that refrigerant
enters the thermal
expansion valve (e.g., from the auxiliary heat exchanger and/or from the
condenser, when
bypassing the auxiliary heat exchanger) prior to entering the evaporator.
Providing cooled
refrigerant at a second temperature may increase a capacity of the evaporator
(e.g., when
compared with the capacity of the evaporator when cooled refrigerant at the
first temperature is
provided).
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Process 600 may be implemented by various systems, such as system 100, 200,
250, 400,
500, 700 (illustrated in FIG. 7), and/or 900 (illustrated in FIG. 9). In
addition, various operations
may be added, deleted, or modified. For example, sensors may be used to
deteimine
temperature(s). As another example, an auxiliary heat exchanger may be a
second condenser
system (e.g., a condenser, a compressor, and/or second refrigerant). A switch
may allow the
second condenser system to function as an auxiliary heat exchanger and be
utilized when
requested by the system and/or users (e.g., the second condenser may be turned
on and/or off).
The second condenser may generate a cold zone that allows heat transfer from
the refrigerant
from the first condenser (e.g., to a second refrigerant). The temperature of
the refrigerant from
the first condenser may be lower when exiting the second condenser than when
entering the
second condenser. For example, the temperature of the refrigerant from the
first condenser may
be reduced by at least approximately two degrees and/or approximately 3
degrees. In some
implementations, the auxiliary heat exchanger may not include a fluid
retention member or
thermoelectric cooler. The auxiliary heat exchanger may include a second
refrigerant, which is
evaporated, compressed and/or condensed to provide a cool zone in the
auxiliary heat exchanger
and cool the refrigerant from the condenser.
In some implementations, a fluid retention member may be utilized to generate
a cold
zone proximate a surface of the auxiliary heat exchanger. FIG. 7 illustrates
an implementation of
an example of a portion 700 of an air conditioner system. The auxiliary heat
exchanger 770 may
include a fluid retention member 730 and a refrigerant line 715 coupled to
opposing surfaces
(e.g., first surface 705 and second surface 710) of a housing 707 (e.g., a
plate) of the auxiliary
heat exchanger. At least a portion of an air flow generated by a fan 720
(e.g., condenser blower
fan and/or a separate auxiliary heat exchanger fan) may be directed across the
fluid retention
member 730. The air flow may facilitate heat transfer between the fluid
retention member 730
and/or fluids 732 residing at least partially in the fluid retention member
and the refrigerant in
the refrigerant line 715. For example, the air flow may cool the fluid
retention member 730
and/or first surface 705 of the housing 707 by allowing evaporation of at
least a part of the fluid
at least partially retained by the fluid retention member. The cooling of the
first surface 705 may
facilitate heat transfer from the refrigerant to the refrigerant conduit,
housing, and/or fluid
retention member, in some implementations.
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Fluids 732 may be delivered to the fluid retention member through distributer
725
coupled to conduit 760. The distributor 725 coupled to the conduit 760 (e.g.,
fluid line from the
container 750) may promote distribution of the condensate approximately evenly
across at least a
portion of the fluid retention member 730. The fluids 732 may include
condensate from the
evaporator 735 and/or water from a water line 740 (e.g., a water line may
connect to a main
water line of the house and/or a municipal water supply). The evaporator
condensate outlet may
be coupled to a sewer line.
The condensate from the evaporator 735 may be collected in a container 750
(e.g., vessel
and/or tank) and/or flow directly through the conduit 760 to the fluid
retention member 730.
The container 750 may be coupled to the evaporator 735 and/or the water line
740. The
container 750 may restrict and/or allow flow from the evaporator 735 and/or
the water line 740.
For example, the container 750 may include sensors that open and close
valve(s) coupled to
line(s) from the evaporator 735 and/or the water line 740. The sensors may
determine a fluid
level in the container 750 and determine whether to allow fluid to enter the
container based on
the determined fluid level. In some implementations, float valve(s) may be
utilized to restrict
and/or allow fluid flow into the container 750 (e.g., a float valve may open
the valve to allow
water from a water line to enter the container when a predetermined low level
is detected by the
float valve and/or the float valve may close the valve to restrict water from
the water line when a
predetermined high level is detected by the float valve).
In some implementations, a pump 755 may be coupled to an exit line (e.g.,
conduit 760)
from the container 750 to deliver fluid to the distributer 755. The evaporator
735 and/or
container 750 may be located at a level below the fluid retention member 730
and the pump may
deliver fluid from the container as desired. For example, the evaporator
and/or container may be
located below grade (e.g., in a basement) and the fluid retention member may
be located at
ground level. The pump may be utilized to deliver fluid to the fluid retention
member. In some
implementations, the evaporator 735 may be located in an attic, for example,
and gravity may
allow the fluid to flow from the container to the fluid retention member
proximate ground level.
FIG. 8 illustrates an example process 800 for operating an auxiliary heat
exchanger that
includes a fluid retention member. A request for the operation of the
auxiliary heat exchanger
may be received (operation 805). For example, a user may request operation of
the auxiliary heat
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exchanger. The air conditioner may include default settings, such as allowing
the auxiliary heat
exchanger to operate unless other instructions are received and/or allowing
the auxiliary heat
exchanger to operate under predetermined circumstances (e.g., at predetermined
temperatures,
the auxiliary heat exchanger may operate or be restricted from operating).
At least a part of the condensate from the evaporator may be allowed to flow
from the
evaporator to the container (operation 810). For example, condensate from the
evaporator may
be collected and flow through a line to a container (e.g., a container
containing condensate and/or
water from other sources) and/or a sewer line.
A determination may be made whether water from the water line should be
allowed to
flow to the container (operation 815). For example, a tank level may be
determined and the
determination whether to open the water line valve to allow fluid flow into
the container may be
made based on the determined tank level. As another example, a tank level may
be determined
and if the tank level is greater than a predetermined maximum tank level, the
condensate from
the evaporator may be restricted from flowing into a container and flow into a
sewer line. The
use of a water line may be based at least partially on operating conditions.
For example, in high
humidity environments, the fluid from the evaporator may satisfy the fluid
needs of the auxiliary
heat exchanger and water from a water line may not be utilized. In less humid
environments, the
water line may be utilized to supplement the condensate collected.
If the determination is made that the water should not be allowed to flow into
the
container from the water line (e.g., the liquid level of fluid in the
container is high), fluid from
the container may be allowed to flow to the fluid retention member (operation
820). For
example, a valve may restrict water flow from the water line. A pump and/or
gravity may deliver
the fluid from the container to the fluid retention member.
If the determination is made that water from the water line should be allowed
to flow to
the container, the water line may be allowed to flow to the container
(operation 825) and fluid
from the container may be allowed to flow to the fluid retention member
(operation 820). For
example, a valve may automatically open and/or close based on a level of the
container and
allow water from the water line to flow and/or be restricted from flowing into
the container. In
some implementations, a valve may not be positioned in the line from the
evaporator and
condensate may not be restricted from flowing into the container.
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At least a part of the liquid refrigerant may be provided from the condenser
to the
auxiliary heat exchanger (operation 830). For example, liquid refrigerant may
be allowed to flow
through a conduit coupled to and/or proximate to a surface of the auxiliary
heat exchanger (e.g.,
a second surface opposed to the first surface proximate the fluid retention
member).
Air flow may be allowed to flow across at least a portion of the fluid
retention member
(operation 835). For example, an opening may be disposed in a housing of the
auxiliary heat
exchanger and air may flow at least partially through the opening and across
at least a portion of
the fluid retention member. The opening may be an opening in a tube (e.g., a
tube with a round,
oval, or other appropriately shaped cross-section) of the auxiliary heat
exchanger. At least
partially controlling the direction of the air flow (e.g., through the opening
and/or design of the
auxiliary heat exchanger) may allow control of the release of the air
processed by the auxiliary
heat exchanger. For example, controlling the air flow through the auxiliary
heat exchanger may
allow the air to return to approximately ambient temperature prior to release.
Heat transfer may be allowed between the refrigerant and the fluid retention
member
(operation 840). In some implementations, the fluid retention member and/or
fluid (e.g.,
condensate and/or water from the water line) may be at a lower temperature
than ambient
temperature (e.g., a temperature proximate a condenser and/or auxiliary heat
exchanger). The
refrigerant may be at a higher temperature than ambient temperature. Heat may
transfer from the
higher temperature refrigerant to the fluid in the fluid retention member by
the air flow across the
fluid retention member (e.g., air flow through the opening in the auxiliary
heat exchanger). Air
flow across the fluid retention member may cool the fluid retention member
(e.g., due to the
evaporation of the fluid at least partially retained). Heat from the
refrigerant may be transferred
to the cooler fluid retention member and thus heat may be removed from the
refrigerant, in some
implementations.
At least a portion of the cooled refrigerant from the auxiliary heat exchanger
may be
provided to the evaporator (operation 845). For example, the air conditioner
may include a
thermal expansion valve that automatically regulates the amount of refrigerant
allowed to enter
the evaporator. The cooled refrigerant from the auxiliary heat exchanger may
flow to the thermal
expansion valve and then the evaporator.
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Process 800 may be implemented by various systems, such as system 100, 200,
250, 400,
500, 700, and/or 900 (illustrated in FIG. 9). In addition, various operations
may be added,
deleted, or modified. For example, refrigerant from the auxiliary heat
exchanger may flow
directly to the evaporator. As another example, the air conditioner may be
allowed to bypass the
auxiliary heat exchanger and flow from the condenser to the thermal expansion
valve and/or
evaporator. In some implementations, a container may not be included.
Condensate and/or water
from the water line may be provided directly to the auxiliary heat exchanger.
In some
implementations, water from the water line may be allowed to flow into the
container and flow
from the evaporator may be restricted.
In some implementations, a thermoelectric cooler may be utilized to generate a
cold zone
proximate a surface of the auxiliary heat exchanger. FIG. 9 illustrates an
implementation of a
portion 900 of an air conditioner. As illustrated, an auxiliary heat exchanger
950 may be coupled
to a power source 932 and a condenser 955. A fan 920 may provide air flow to
the auxiliary heat
exchanger 950 and/or the condenser 955. The power source 932 may be the same
power source
for the air conditioner and/or a different power source. The auxiliary heat
exchanger may include
a converter 925 coupled to the theimoelectric cooler 930. The converter 925
may convert, for
example, alternating current from the power source 932 to a direct current for
the thermoelectric
cooler 930. The thermoelectric cooler 930 may be coupled to a housing 940,
such as a plate, of
the auxiliary heat exchanger 950. The thermoelectric cooler 930 may generate a
temperature
proximate a first surface 905 of the housing 940 of the auxiliary heat
exchanger 950 that is lower
than ambient temperature (e.g., temperature proximate the condenser 955 and/or
auxiliary heat
exchanger). The refrigerant in the refrigerant conduit 915 may be coupled to a
second surface
910 of the housing 940 of the auxiliary heat exchanger 950 that is opposed to
the first surface
905. The refrigerant in the refrigerant line 915 may be at a temperature
higher than ambient
temperature. Air may flow across a hot side of the thermoelectric cooler. The
air may remove
heat from the thermoelectric cooler and/or inhibit overheating. This may
facilitate heat transfer
between the thermoelectric cooler 930 and the refrigerant in the refrigerant
conduit 915.
FIG. 1000 illustrates an implementation of an example process 1000 for
operation of an
auxiliary heat exchanger that includes a thermoelectric cooler. A request for
operation of the
auxiliary heat exchanger may be received (operation 1005). For example, an air
conditioner may
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have a predetermined setting that allows operation of the auxiliary heat
exchanger. The request
for operation may include an initial installation design (e.g., a default .
setting) that directs
refrigerant flow to the auxiliary heat exchanger.
A current from a power source may be provided (operation 1010). For example,
the
power source may be a 240V alternating current power source. The power source
may be a
battery. The power source may provide power to the thermoelectric cooler. A
current from the
power source may be converted (operation 1015). For example, an AC-DC
converter may be
utilized. The converted current may be provided to the thermoelectric cooler
(operation 1020).
For example, wires may couple the power source, converter, and/or
thermoelectric cooler(s).
At least a part of the liquid refrigerant from the condenser may be provided
to the
auxiliary heat exchanger (operation 1025). For example, a line may couple the
condenser and a
portion of the auxiliary heat exchanger. Refrigerant may be allowed to flow
through an inlet of
the refrigerant line in the auxiliary heat exchanger and out of an outlet of
the refrigerant line in
the auxiliary heat exchanger.
Air may be allowed to flow across at least a portion of the thermoelectric
cooler
(operation 1030). For example, air may flow across at least a portion of a hot
side of a
thermoelectric cooler.
Heat transfer may be allowed between the refrigerant in the auxiliary heat
exchanger and
the thermoelectric cooler (operation 1035). The refrigerant may be at a higher
temperature than
the theimoelectric cooler and thus heat may be transferred to the
theimoelectric cooler from the
refrigerant in the refrigerant conduit. The refrigerant may exit the auxiliary
heat exchanger at a
temperature at or below approximately ambient temperature.
Cooled refrigerant maybe provided to the evaporator (operation 1040). For
example, the
refrigerant may flow to a thermal expansion valve and/or to the evaporator
from the auxiliary
heat exchanger. The cooled refrigerant may have a temperature of at least
three degrees
Fahrenheit above an ambient temperature (e.g., proximate the auxiliary heat
exchanger and/or
the temperature of the air disposed in the opening in the auxiliary heat
exchanger). As another
example, the cooled refrigerant may have a temperature below ambient
temperature.
Process 1000 may be implemented by various systems, such as system 100, 200,
250,
400, 500, 700, and/or 900. In addition, various operations may be added,
deleted, or modified.
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For example, an auxiliary heat exchanger may include a fluid retention member
and a
thermoelectric cooler and various operations of' process 1000 and 900 may be
performed. As
another example, a converter may not be utilized. In some implementations, a
determination may
be made whether a request for operation of the auxiliary heat exchanger has
been received. If the
detemiination has been made that the request for operation of the auxiliary
heat exchanger has
not been received, the auxiliary heat exchanger may be bypassed. In some
implementations, the
refrigerant may flow though the auxiliary heat exchanger, but the auxiliary
heat exchanger may
be turned off (e.g., air flow from fan may be inhibited and/or the
thermoelectric cooler may be
turned off). When the auxiliary heat exchanger is turned off, the temperature
of the refrigerant
entering the auxiliary heater exchanger may not be substantially reduced.
In some implementations, the auxiliary heat exchanger and/or portions thereof
may be a
retrofit kit. The retrofit kit may allow existing air conditioners without
auxiliary heat exchangers
to be altered to include auxiliary heat exchangers. A user may couple the
auxiliary heat
exchanger to at least a portion of the air conditioner. A refrigerant line
between a condenser and
thermal expansion valve and/or evaporator may be altered such that the
refrigerant flows through
the auxiliary heat exchanger prior to flowing through the thermal expansion
valve and/or
evaporator.
In some implementations, the auxiliary heat exchanger may be provided in an
air
conditioner prior to operation and/or installation at a location. The air
conditioner may restrict
use of the air conditioner without the auxiliary heat exchanger operation, in
some
implementations.
In some implementations, various described system(s) and/or operation of the
various
described process(es) may increase an EER (energy efficiency ratio) rating
and/or SEER
(seasonal energy efficiency ratio) rating by at least approximately 0.5 point.
The EER and/or
SEER rating may be increased by from approximately 0.5 to approximately 1
point.
In various implementations, fluid, such as air from a condenser fan is
described as being
provided to various components of the air conditioner, such as the auxiliary
heat exchanger. In
some implementations, the auxiliary heat exchanger may include a fan separate
from the
condenser fan.
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Although various lines (e.g., refrigerant line) have been described, a line
may include any
appropriate conduit for transporting fluids, such as tubes, pipes, and/or
ducts. Although various
fans have been described, any appropriate fan may be utilized, such as axial,
centrifugal, etc.
Although a specific implementation of the system is described above, various
components may be added, deleted, and/or modified. In addition, the fluids are
described for
exemplary purposes. Fluids may vary, as appropriate. For example, a
refrigerant may include any
appropriate heat transfer fluid. Although air has been described as provided
by various fans to
component(s), any appropriate fluid may be utilized. Although water has been
described as being
provided to a fluid retention member, container, and/or distributer, any
appropriate fluid may be
utilized. For example, water from the condensate and/or sewer line may include
various
impurities. A fluid may be a gas and/or a liquid. For example, although the
refrigerant has been
described as gaseous and/or liquid, the refrigerant may include gas and/or
liquid in various
portions of the air conditioner and/or auxiliary heat exchanger.
Although a cooling cycle has been described, the air conditioner may be
operable when
flow is reversed (e.g., a reversible valve may be included to reverse the flow
of refrigerant in the
system), in some implementations, to provide a heating cycle. In some
implementations, one or
more of the various described systems may be utilized and/or processes may be
performed in
conjunction with a system that allows cooling and/or heating, as appropriate.
Although fans have been described, any appropriate blower may be utilized
(e.g.,
centrifugal fan, cross-flow Ian, and/or axial fan). A controller may include
any appropriate
computing device such as a server and/or any other appropriate programmable
logic device.
Although processes 600, 800, and 1000 have been described separately, various
operations from processes 600, 800, and 1000 may be combined, deleted, and/or
modified. For
example, one or more of the operations in process 600 and one or more of the
operations from
process 800 may be combined. As another example, one or more of the operations
from process
800 and one or more of the operations from process 1000 may be combined.
The systems and methods discussed above allow for cooling refrigerant in two
stages
using condenser 120 and auxiliary heat exchanger 130. Additional examples of
two-stage
cooling are further described with respect to FIGURES 11-14 below.
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FIGURE 11 illustrates an implementation of an example refrigeration system
comprising
a multi-stage cooler. The refrigeration system comprises a flash tank 1105,
one or more
evaporator valves 1110 corresponding to one or more evaporators 1115, one or
more
compressors 1120, an oil separator 1125, a gas cooler 1130, an expansion valve
1150, and a flash
gas bypass valve 1155. As depicted in FIGURE 11, the refrigeration system
includes two
evaporator valves (1110A and 1110B) corresponding to two evaporators (1115 A
and 1115B),
and two compressors (1120A and 1120B). Each component may be installed in any
suitable
location, such as a mechanical room (e.g., the flash tank 1105 and compressors
1120 may be in a
mechanical room), in a consumer-accessible location (e.g., evaporators 1115
may be located on a
sales floor), or outdoors (e.g., gas cooler 1130 may be located on a rooftop).
In general, flash tank 1105 supplies liquid refrigerant to first evaporator
1115A and
second evaporator 1115B via evaporator valves 1110A and 1110B, respectively.
Evaporator
valves 1110A and 1110B may comprise expansion valves. Valves 1110A and 1110B
may
receive the liquid refrigerant from the flash tank 1105 at the same
temperature and pressure, and
each valve 1110 may be controlled (e.g., by a controller) to adjust the
pressure of the liquid
refrigerant in order to control the temperature of the refrigerant supplied to
its respective
evaporator 1115.
In certain embodiments, first evaporator 1115A is operable to evaporate the
refrigerant in
order to cool a first case (or set of cases). As an example, the first case
may be a low-
temperature ("LT") case, such as a grocery store display case used to store
frozen food. In
certain embodiments, second evaporator 1115B is operable to evaporate the
refrigerant in order
to cool a second case (or set of cases). As an example, the second case may be
a medium-
temperature ("MT") case, such as a grocery store display case used to store
fresh food. Thus, the
second case (MT case) has a higher temperature set point than the first case
(LT case). As an
example, the MT case may be set to -6 C and the LT case may be set to -30 C.
In some embodiments, first evaporator 1115A may be configured to discharge
warm
refrigerant vapor to first compressor 1120A (also referred to herein as an LT
compressor
1120A). First compressor 1120A provides a first stage of compression to the
warmed refrigerant
from the first evaporator 1115A and discharges the compressed refrigerant to
second compressor
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1120B for further compression. Second evaporator 1115B also discharges warm
refrigerant
vapor to second compressor 1120B (also referred to herein as an MT compressor
1120B).
Second compressor 1120B discharges compressed refrigerant to gas cooler 1130
for
cooling. In some embodiments, refrigeration system may include an oil
separator 1125 that
separates compressor oil from the refrigerant prior to flowing the refrigerant
to gas cooler 1130.
Gas cooler may include multiple stages, such as an air-cooled stage 1132 and
an evaporative
stage 1134. The air-cooled stage 1132 is operable to apply a first cooling
stage to the refrigerant
discharged from the second compressor 1120B. The evaporative stage 1134 is
operable to apply
a second cooling stage to the refrigerant discharged from the air-cooled stage
1132. The air-
cooled stage 1132 and evaporative stage 1134 may be arranged in any suitable
manner. For
example, the air-cooled stage 1132 and evaporative stage 1134 can be contained
within the same
housing. Alternatively, the air-cooled stage 1132 and the evaporative stage
1134 could be
contained in separate housings, in which case the outlet of the air-cooled
stage 1132 may connect
to the inlet of the evaporative stage 1134 through any suitable conduit.
The air-cooled stage 1132 may comprise one or more fans (e.g., fan 1136A)
operable to
circulate ambient air over a conduit that circulates the refrigerant through
the air-cooled stage.
As an example, in certain embodiments, the air-cooled stage 1132 may be an air-
cooled
condenser (e.g., if the ambient temperature is low, the refrigerant pressure
could be lower than
the critical point) or an air-cooled gas cooler (e.g., if the ambient
temperature is high, the
refrigerant pressure could be higher than the critical point). The condenser
utilizes fans and
vents to pull in surrounding air and circulate the air around condenser coils
that have been heated
by the warm refrigerant received from compressor 1120B. The heat from the
refrigerant is
transferred to the circulating air, and the hot air is vented away from the
refrigerant.
Because the air-cooled stage uses ambient air to cool the refrigerant, it is
able to cool the
refrigerant to a temperature near the dry bulb ambient temperature. For
example, in certain
embodiments, the temperature of the refrigerant may decrease to a value, for
example, 5 F above
dry bulb ambient temperature. If the surrounding air is warm or hot, the fans
and vents of the
air-cooled condenser will suck the warm air into the unit and try to cool off
the condenser with
that warm air. Thus, particularly in warm or hot environments, the refrigerant
discharged from
the air-cooled stage 1132 may still be relatively warm. The refrigerant may
proceed to the
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evaporative cooling stage 1134 to further cool the refrigerant to a
temperature at which the
refrigeration system may run more efficiently.
The evaporative stage 1134 comprises one or more nozzles (e.g., 1138A-C)
operable to
dispense water over a conduit that circulates the refrigerant through the
evaporative stage. The
evaporative stage 1134 may also comprise one or more fans (e.g., 1136B) that
may direct the
water (and ambient air) toward the conduit in order to facilitate the
evaporative cooling. In
certain embodiments, the water is supplied to nozzles 1138 from a tap 1140.
Condensate from
the evaporator and/or water that passes over the conduit without evaporating
can be collected in
a reservoir 1142 and discharged through a drain 1144 (for example, to a
sewer). In certain
embodiments, the evaporative stage 1134 of gas cooler 1130 decreases the
temperature of the
refrigerant further, for example, to 5 F below the dry bulb ambient
temperature.
Gas cooler 1130 may further comprise an outlet operable to discharge the
cooled
refrigerant to an expansion valve 1150 that supplies refrigerant to the flash
tank 1105 from which
first evaporator 1115A and the second evaporator 1115B receive refrigerant.
Expansion valve
1150 may be configured to reduce the pressure of refrigerant and reduce flash
gas flow rate to
the flash tank 1105. In some embodiments, this reduction in pressure causes
some of the
refrigerant to vaporize. As a result, mixed-state refrigerant (e.g.,
refrigerant vapor and liquid
refrigerant) is discharged from expansion valve 1150 to flash tank 1105. Flash
tank 1105 may be
configured to receive mixed-state refrigerant and separate the received
refrigerant into flash gas
and liquid refrigerant. The liquid refrigerant flows from flash tank 1105 to
evaporators 1115,
and the flash gas flows through flash gas bypass valve 1155 to one or more
compressors (e.g.,
MT compressor 1220B) for compression.
In some embodiments, refrigeration system 100 may be configured to circulate
natural
refrigerants such as carbon dioxide (CO2), water, air, and hydrocarbon (HC)
(e.g., propane
(C3H8) or isobutane (C4I-110)). Natural refrigerants may be associated with
various
environmentally conscious benefits (e.g., they do not contribute to ozone
depletion and/or global
warming effects). As an example, certain embodiments can be implemented in a
transcritical
refrigeration system (i.e., a refrigeration system in which the heat rejection
process occurs above
the critical point). In a transcritical refrigeration system, first compressor
1120A can comprise a
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subcritical compressor and second compressor 1120B can comprise a
transcritical compressor.
Other embodiments may use different types of refrigerant, such as
hydrofluorocarbon (HFC).
FIGURE 12 illustrates an implementation of an example refrigeration system
comprising
a multi-stage cooler. The refrigeration system depicted in FIGURE 12 is
generally similar to the
refrigeration system discussed above with respect to FIGURE 11. For example,
the refrigeration
system depicted in FIGURE 12 includes a flash tank 1205 (similar to flash tank
1105 of FIG.
11), evaporator valves 1210 (similar to evaporator valves 1110 of FIG. 11),
evaporators 1215
(similar to evaporators 1115 of FIG. 11), compressors 1220 (similar to
compressors 1120 of FIG.
11), oil separator 1225 (similar to oil separator 1125 of FIG. 11), gas cooler
1230 (discussed
below), expansion valve 1250 (similar to expansion valve 1150 of FIG. 11) and
flash gas bypass
valve 1255 (similar to flash gas bypass valve 1155 of FIG. 11).
Gas cooler 1230 includes an air-cooled stage 1232 similar to the air-cooled
stage 1132 of
FIG. 11. For example, the air-cooled stage 1232 may comprise one or more fans
(e.g., fan
1236A) operable to cool the refrigerant by circulating ambient air over a
conduit that flows the
refrigerant through the air-cooled stage.
Gas cooler 1230 also includes an evaporative stage 1234. The evaporative stage
1234
comprises one or more nozzles (e.g., 1238A-C) operable to dispense water over
a conduit that
circulates the refrigerant through the evaporative stage. The evaporative
stage 1234 may also
comprise one or more fans (e.g., 1236B) that may direct the water (and ambient
air) toward the
conduit in order to facilitate the evaporative cooling. In certain
embodiments, the water is
supplied to nozzles 1238 from a pump 1246. Condensate from the evaporator
and/or water that
passes over the conduit without evaporating can be collected in a reservoir
1142 and re-
circulated to nozzles 1238 via pump 1246. In certain embodiments, the
evaporative stage 1134
of gas cooler 1130 decreases the temperature of the refrigerant further, for
example, to 5 F
below the dry bulb ambient temperature.
This disclosure recognizes that a refrigeration system, such as that depicted
in FIGURE
11 and FIGURE 12, may comprise one or more other components. As an example,
the
refrigeration system may comprise one or more parallel compressors, ejectors,
sensors,
desuperheaters, and/or other components in some embodiments. As another
example, the
refrigeration system may comprise a controller operable to control the
operation of the system.
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The controller may include any suitable interface (e.g., wired or wireless
interfaces), processing
circuitry (e.g., one or more computers, one or more central processing units
(CPUs), one or more
microprocessors, one or more applications, one or more application specific
integrated circuits
(ASICs), one or more field programmable gate arrays (FPGAs), and/or other
logic), memory
(e.g., Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage
media (for
example, a hard disk), removable storage media (for example, a Compact Disk
(CD) or a Digital
Video Disk (DVD)), database and/or network storage (for example, a server),
and/or other
computer-readable medium), etc. for performing the described functionality.
One of ordinary
skill in the art will appreciate that the refrigeration system may include
other components not
mentioned herein.
A two-stage gas cooler similar to the one depicted in FIGURES 11-12 could be
used in
various environments, such as a CO2 transcritical refrigeration system for a
supermarket (or for
an industrial application) in a hot and dry climate, an HFC refrigeration
system for a supermarket
(or for an industrial application ) in a hot and dry climate, an air
conditioning system with direct
condenser cooling in a hot and dry climate, or other suitable environment.
FIGURE 13 illustrates an example of a method cooling a refrigerant using a
multi-stage
system. At step 1305, the method applies a first cooling stage to refrigerant
discharged from a
compressor. The refrigerant may comprise carbon dioxide (CO2),
hydrofluorocarbon (HFC), or
other suitable refrigerant. The first cooling stage comprises air-cooling,
such as described with
respect to the air-cooled stage 1132 and 1232 above. In certain embodiments,
the air-cooled
stage decreases the temperature of the refrigerant to a value, for example, 5
F above dry bulb
ambient temperature.
Certain embodiments of the method may optionally include step 1310. At step
1310, the
method determines whether the refrigerant discharged from the first cooling
stage is greater than
or less than a pre-determined threshold. In response to determining that the
refrigerant
discharged from the first cooling stage is greater than the pre-determined
threshold, the method
may proceed to step 1315. At step 1315, the method applies a second cooling
stage to the
refrigerant discharged from the first cooling stage. The second cooling stage
comprises
evaporative cooling, such as described with respect to the evaporative stage
1134 and 1234
discussed above. The evaporative stage may comprise cooling the refrigerant
through the
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evaporation of water dispensed via one or more nozzles. The water may be
supplied to the
nozzles from a tap (e.g., FIG. 11) or from a pump that pumps water from a
reservoir that collects
condensate or run-off from the nozzles (e.g., FIG. 12). In certain
embodiments, the evaporative
stage decreases the temperature of the refrigerant to, for example, 5 F below
the dry bulb
ambient temperature.
At step 1320, the method supplies the cooled refrigerant to expansion valve
(e.g., 1150 or
1250) with less vapor at outlet. The flash tank (e.g., 1105 or 1205) may
receive the refrigerant
from the gas cooler outlet via the expansion valve and may flow the
refrigerant to the evaporator
(e.g., 1115) via an evaporator valve (e.g., 1110). The evaporator is operable
to cool a space. As
an example, the evaporator may be a component of an air conditioner operable
to cool a building.
As another example, the evaporator may be a component of a refrigeration
system operable to
cool a refrigerated case or a freezer.
Referring back to step 1310, if it had been determined that the refrigerant
discharged
from the first cooling stage is less than the pre-determined threshold, the
method may be further
operable to bypass the second cooling stage (skip step 1315) and proceed
directly to step 1320.
As an example, at cool ambient temperatures, the air-cooled stage may provide
adequate
efficiency on its own such that it may make sense to bypass the evaporative
stage in order to
conserve water. In some embodiments, the threshold may be determined at least
in part based on
whether the system is located in a dry climate. If the refrigerant discharged
from the first cooling
stage subsequently increases above the threshold, the method may resume use of
the second
cooling stage.
In certain embodiments, the determination whether to use or bypass the second
cooling
stage may be performed by a controller operable to determine the temperature
of refrigerant
discharged from the first cooling stage (e.g., based on information from a
sensor that measures
the air-cooler outlet temperature or the dry bulb ambient temperature),
compare the temperature
to the pre-determined threshold (e.g., the threshold may be determined based
on a parameter
setting or based on applying a rule to information obtained from one or more
sensors), and turn
the second stage cooling on or off depending on whether the temperature is
greater than or less
than the threshold.
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Modifications, additions, or omissions may be made to the method of FIGURE 13
without departing from the scope of the disclosure. The method may include
more, fewer, or
other steps. Additionally, steps may be performed in any suitable order.
A multi-stage gas cooler, such as gas cooler 1130 or 1230 of FIG. 11 or 12,
may allow
for more energy efficient cooling compared to refrigeration systems that only
use air-cooling and
may allow for more water-efficient cooling compared to refrigeration systems
that only use
evaporative cooling. In certain embodiments, the multi-stage gas cooler can
save 50-80% of
water compared to an evaporative type gas cooler. In certain embodiments, the
multi-stage gas
cooler can improve system efficiency 10-20% at the design condition compared
to existing air
cooled systems. An example of the efficiencies that can be realized using the
multi-stage gas
cooler is provided in FIGURE 14. FIGURE 14 provides a graph depicting enthalpy
(Btu/1pm)
along the x-axis and temperature ( F) along the y-axis. In the example, CO2
refrigerant is cooled
to approximately 95 F during the air cooled stage and is further cooled to
approximately 80 F
during the evaporative stage.
It is to be understood the implementations are not limited to particular
systems or
processes described which may, of course, vary. It is also to be understood
that the terminology
used herein is for the purpose of describing particular implementations only,
and is not intended
to be limiting. As used in this specification, the singular forms "a", "an"
and "the" include plural
referents unless the content clearly indicates otherwise. Thus, for example,
reference to "a
surface" includes a combination of two or more surfaces and reference to "a
fluid" includes
different types and/or combinations of fluids. As another example, "water" may
include
components other than water and/or in addition to water. Coupling may include
direct and/or
indirect coupling. Although a system with one auxiliary heat exchanger and/or
one type of
auxiliary heat exchanger has been described, a system may include more than
one auxiliary heat
exchanger and/or type of heat exchanger.
Although the present disclosure has been described in detail, it should be
understood that
various changes, substitutions and alterations may be made herein without
departing from the
spirit and scope of the disclosure as defined by the appended claims.
Moreover, the scope of the
present application is not intended to be limited to the particular
embodiments of the process,
machine, manufacture, composition of matter, means, methods and steps
described in the
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specification. As one of ordinary skill in the art will readily appreciate
from the disclosure,
processes, machines, manufacture, compositions of matter, means, methods, or
steps, presently
existing or later to be developed that perform substantially the same function
or achieve
substantially the same result as the corresponding embodiments described
herein may be utilized
according to the present disclosure. Accordingly, the appended claims are
intended to include
within their scope such processes, machines, manufacture, compositions of
matter, means,
methods, or steps.
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