U.S. patent application number 11/351677 was filed with the patent office on 2006-08-10 for system and method for operating a condenser at low ambient conditions.
Invention is credited to Curtis W. Caskey, Douglas A. Kester, Anthony J. Reardon.
Application Number | 20060174640 11/351677 |
Document ID | / |
Family ID | 36570311 |
Filed Date | 2006-08-10 |
United States Patent
Application |
20060174640 |
Kind Code |
A1 |
Caskey; Curtis W. ; et
al. |
August 10, 2006 |
System and method for operating a condenser at low ambient
conditions
Abstract
A condenser arrangement for control of condenser temperature and
condenser pressure. The condenser arrangement includes a condenser
coil and a plurality of fans disposed adjacent to the condenser
coil. The plurality of fans are arranged and disposed to circulate
air through the condenser coil. At least one baffle is positioned
between adjacent fans of the plurality of fans and forms a
plurality of channels extending from a surface of the condenser
coil. The channels include a variable flow channel having a
plurality of adjacent fans of the plurality of fans. The condenser
arrangement also includes a control system to control operation of
the plurality of fans. The control system is configured to
independently control each fan of the plurality of fans in response
to a sensed condition.
Inventors: |
Caskey; Curtis W.; (York,
PA) ; Kester; Douglas A.; (York, PA) ;
Reardon; Anthony J.; (Columbia, PA) |
Correspondence
Address: |
MCNEES, WALLACE & NURICK LLC
100 PINE STREET
P.O. BOX 1166
HARRISBURG
PA
17108-1166
US
|
Family ID: |
36570311 |
Appl. No.: |
11/351677 |
Filed: |
February 10, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60651723 |
Feb 10, 2005 |
|
|
|
Current U.S.
Class: |
62/183 ;
62/507 |
Current CPC
Class: |
F25B 2700/21161
20130101; Y02B 30/743 20130101; F25B 49/027 20130101; F25B 2600/111
20130101; F25B 2400/075 20130101; Y02B 30/70 20130101; F25B
2700/2106 20130101 |
Class at
Publication: |
062/183 ;
062/507 |
International
Class: |
F25B 39/04 20060101
F25B039/04 |
Claims
1. A condenser arrangement comprising: a condenser coil; a
plurality of fans disposed adjacent to the condenser coil, the
plurality of fans being arranged and disposed to circulate air
through the condenser coil; at least one baffle positioned between
adjacent fans of the plurality of fans, the at least one baffle is
configured and disposed to form a plurality of channels extending
from a surface of the condenser coil, the plurality of channels
including at least one variable flow channel having two or more
fans of the plurality of fans to control airflow through the at
least one variable flow channel; and a control system to control
operation of the plurality of fans; the control system being
configured to independently control each fan of the plurality of
fans in response to a sensed condition to obtain a desired
condenser operating condition.
2. The condenser arrangement of claim 1, wherein the at least on
baffle forms a plurality of variable flow channels having two or
more fans of the plurality of fans to control airflow through the
plurality of variable flow channels.
3. The condenser arrangement of claim 1, wherein the condenser
arrangement includes a plurality of baffles.
4. The condenser arrangement of claim 1, wherein the sensed
conditions are selected from the group consisting of refrigerant
pressure, refrigerant temperature, inlet air temperature, outlet
air temperature, and combinations thereof.
5. The condenser arrangement of claim 1, wherein the control system
activates and deactivates a predetermined combination of the
plurality of fans in response to the sensed condition.
6. The condenser arrangement of claim 1, further comprising at
least one constant flow channel formed by the at least one baffle,
wherein the constant flow channel includes an airflow that is
substantially constant in a substantially singular direction when
the fan or fans arranged to circulate air through the constant flow
channel are operating.
7. An HVAC system comprising: a compressor, an evaporator and a
condenser arrangement connected in a closed refrigerant loop; the
condenser arrangement includes a condenser coil and a plurality of
fans disposed adjacent to the condenser coil, the plurality of fans
being arranged and disposed to circulate air through the condenser
coil; at least one baffle positioned between adjacent fans of the
plurality of fans, the at least one baffle is configured and
disposed to form a plurality of channels extending from a surface
of the condenser coil, the plurality of channels including at least
one variable flow channel having two or more fans of the plurality
of fans to control airflow through the at least one variable flow
channel; and a control system to control operation of the plurality
of fans; the control system being configured to independently
control each fan of the plurality of fans in response to a sensed
condition to obtain a desired condenser operating condition.
8. The condenser arrangement of claim 7, wherein the at least on
baffle forms a plurality of variable flow channels having two or
more fans of the plurality of fans to control airflow through the
plurality of variable flow channels. The system of claim 7, wherein
the condenser arrangement includes a plurality of baffles.
9. The system of claim 7, wherein the sensed conditions are
selected from the group consisting of refrigerant pressure,
refrigerant temperature, inlet air temperature, outlet air
temperature, and combinations thereof.
10. The system of claim 7, wherein the control system activates and
deactivates a predetermined combination of the plurality of fans in
response to the sensed condition.
11. The system of claim 7, wherein the system comprises a plurality
of compressors connected in the closed refrigerant loop.
12. The system of claim 7, wherein the system comprises a plurality
of closed refrigerant loops, wherein each of the plurality of
closed refrigerant loops includes the condenser arrangement.
13. The system of claim 7, further comprising at least one constant
flow channel formed by the at least one baffle, wherein the
constant flow channel includes an airflow that is substantially
constant in a substantially singular direction when the fan or fans
arranged to circulate air through the constant flow channel are
operating.
14. A method for controlling a condenser operating condition
comprising: providing a condenser arrangement having a condenser
coil, a plurality of fans disposed adjacent to the condenser coil,
and a plurality of channels extending from a surface of the
condenser coil, the channels including a variable flow channel
having two or more fans of the plurality of fans to control airflow
through the variable flow channel; circulating air through the
condenser coil by activating one or more of the plurality of fans;
sensing a condition of refrigerant in the condenser coil or a
condition of inlet air to the condenser coil; and deactivating at
least one fan of the two or more fans of the variable flow channel
in response to sensed condition to provide a mixture of air being
discharged from the variable flow channel comprising air through
the condenser coil and bypass air from an area adjacent a
deactivated fan.
15. The method of claim 15, wherein the sensing step includes
sensing conditions selected from the group consisting of
refrigerant pressure, refrigerant temperature, inlet air
temperature, outlet air temperature, and combinations thereof.
16. The method of claim 16, wherein the step of deactivating is in
response to a sensed refrigerant pressure.
17. The method of claim 16, wherein the step of deactivating is in
response to a sensed inlet air temperature
18. The method of claim 15, wherein the step of deactivating
includes deactivation of a predetermined combination of two or more
fan of the variable flow channel.
19. The method of claim 15, further comprising circulating air
through at least one constant flow channel formed by the at least
one baffle, wherein the constant flow channel provides airflow that
is substantially constant in a substantially singular direction.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a condenser
arrangement for a heating, ventilation, and air conditioning (HVAC)
system.
BACKGROUND OF THE INVENTION
[0002] An HVAC system generally includes a closed loop
refrigeration system with at least one evaporator, at least one
condenser and at least one compressor. As the refrigerant travels
through the evaporator, it absorbs heat from a heat transfer fluid
to be cooled and changes from a liquid to a vapor phase. After
exiting the evaporator, the refrigerant proceeds to a compressor,
then a condenser, then an expansion valve, and back to the
evaporator, repeating the refrigeration cycle. The fluid to be
cooled passes through the evaporator in a separate fluid channel
and is cooled by the evaporation of the refrigerant. The cooled
fluid can then be sent to a distribution system for cooling the
spaces to be conditioned, or it can be used for other refrigeration
purposes.
[0003] High capacity HVAC systems may include multiple refrigerant
circuits or multiple compressors connected in the refrigerant loop.
Air-cooled refrigeration systems that utilize multiple compressors,
arranged in tandem (parallel), typically utilize a single condenser
coil that is sized to handle the load of all of the compressors
operating simultaneously. This results in a condenser that has
excessive heat exchange capacity when less than all of the
compressors in the system are operating, essentially making the
condenser coils oversized for the system operating. Making this
problem worse, condenser coils are often manufactured oversized,
with corresponding increased airflows, with respect to the system
full load requirements, in order to meet the ever-increasing
efficiency requirements for modern refrigeration systems. The
condensers present in these systems are typically installed
outdoors and/or in locations subject to outdoor ambient conditions,
particularly temperature. When the outdoor ambient temperature
falls, the amount of heat being removed from the refrigerant in the
condenser increases. The increased heat removal in the condenser
can result in a decrease in the refrigerant pressure at the suction
line to the compressor. A decrease in suction pressure to the
compressor results in a lowering of the temperature of the
refrigerant at the evaporator. However, when the temperature of the
refrigerant at the evaporator becomes too low, system performance
suffers. If the suction pressure falls too low, the system may
experience problems, such as evaporator freezing, liquid slugging
at the compressor and/or system instability.
[0004] In addition to the problem of an oversized condenser coil,
there is a need to decrease the condenser "capacity" in order to
maintain proper system operation. One approach to provide good
system control and offset the excessive cooling that may result
from an oversized coil includes a variable speed condenser fan used
to control airflow over the condenser coil. As the amount of air
passing over the coil decreases, the amount of heat transfer taking
place at the coil decreases. Therefore, the temperature of the
refrigerant in the condenser and the pressure of the system
increase to allow the evaporator to cool the heat transfer fluid
without system performance problems. The use of the variable speed
condenser fan has the drawback that it is expensive and requires
complicated wiring and controls. An alternate method used for
condenser airflow control is to utilize multiple small condenser
fans that may be cycled on and off as necessary. However, the flow
resulting from multiple small condensers is stepped and provides
predetermined levels of cooling capacity at the condenser based
upon the number of fans activated. To provide adequate control a
very large number of fans and independent controls for each fan are
required, which is expensive and requires complicated wiring and/or
controls.
[0005] Air-cooled condensers that are oversized often result in a
system performance that degrades rapidly as the ambient temperature
of the condenser air decreases. In order for these types of systems
to operate effectively and reliably, the amount of cooling taking
place at the condenser has to be reduced as the ambient temperature
decreases. As discussed above, a common way to vary the performance
of the condenser coil at lower ambient temperatures is to use
multiple condenser fans controlled in such a way as to decrease the
number of fans that are operating. As the number of fans in
operation decreases, the volume of air drawn through the condenser
coil is likewise decreased. Unfortunately, to provide sufficient
control, particularly at low ambient temperature conditions, there
must be a large number of condenser fans used, or excessive fan
cycling will occur. Excessive fan cycling increases the amount of
energy required to operate the condenser and increases the wear on
the fans, which increases maintenance costs. This excessive fan
cycling is due to the fact that the operating ambient temperature
range when a fan is activated versus when the same fan is
deactivated can have a significant gap. For example, the operating
ambient temperature range for one system having a single fan
activated may be 20.degree. F.-35.degree. F. However, the same
system may include an operating ambient temperature range of
45.degree. F.-60.degree. F. for two fans activated. Operational
problems occur for this condenser system if the ambient temperature
is between about 35.degree. F. and 45.degree. F. In this
temperature range, the second condenser fan may be cycled
repeatedly with relatively small changes in temperature.
[0006] Therefore, what is needed is a method and apparatus for
improving low ambient temperature operation and reliability in a
high efficiency condenser, while not sacrificing high ambient
temperature performance and overall system efficiency.
SUMMARY OF THE INVENTION
[0007] The present invention includes a condenser arrangement for
control of condenser temperature and condenser pressure and an HVAC
system employing the condenser arrangement. The condenser
arrangement includes a condenser coil and a plurality of fans
disposed adjacent to the condenser coil. The plurality of fans are
arranged and disposed to circulate air through the condenser coil.
At least one baffle extending from a surface of the condenser coil
is positioned between adjacent fans of the plurality of fans and
forms a plurality of channels. The plurality of channels include a
variable flow channel having a plurality of adjacent fans of the
plurality of fans to control airflow through the channel. The
condenser arrangement also includes a control system to control
operation of the plurality of fans. The control system is
configured to independently control each fan of the plurality of
fans in response to a sensed condition.
[0008] The present invention also includes a method for controlling
condenser pressure. The method includes providing a condenser
arrangement having a condenser coil, a plurality of fans disposed
adjacent to the condenser coil, and a plurality of channels
extending from a surface of the condenser coil. The plurality of
channels include a variable flow channel having a plurality of
adjacent fans of the plurality of fans to control airflow through
the channel. Air is circulated through the condenser coil by
activating one or more of the plurality of fans. A condition of
refrigerant in the condenser coil or a condition of inlet air to
the condenser coil is sensed. At least one fan of the plurality of
fans of the variable flow channel is deactivated in response to the
sensed condition to lower airflow through the condenser coil. At
least one active fan of the plurality of fans draws bypass air from
an area adjacent to the at least one deactivated fan to further
lower airflow through the condenser coil.
[0009] One advantage of the present invention is that condenser fan
cycling is significantly reduced or even eliminated at all but the
lowest ambient temperatures.
[0010] Another advantage of the present invention is improved
system control by improving the overlaps in condenser performance
between condenser fan stages.
[0011] Still another advantage of the present invention is that
fewer condenser fans can be used resulting in a lower system
cost.
[0012] Other features and advantages of the present invention will
be apparent from the following more detailed description of the
preferred embodiment, taken in conjunction with the accompanying
drawings which illustrate, by way of example, the principles of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates an embodiment of the present invention
used in an HVAC or chiller system.
[0014] FIG. 2 illustrates an embodiment of the condenser
arrangement of the present invention.
[0015] FIG. 3 illustrates the embodiment of the condenser
arrangement shown in FIG. 2 operating according to an embodiment of
the invention.
[0016] FIG. 4 illustrates the embodiment of the condenser
arrangement shown in FIG. 2 operating according to another
embodiment of the invention.
[0017] FIG. 5 illustrates the embodiment of the condenser
arrangement shown in FIG. 2 operating according to still anther
embodiment of the invention.
[0018] FIG. 6 illustrates the embodiment of the condenser
arrangement shown in FIG. 2 operating according to still anther
embodiment of the invention.
[0019] FIG. 7 illustrates an alternate embodiment of the condenser
arrangement of the present invention.
[0020] Wherever possible, the same reference numbers will be used
throughout the drawings to refer to the same or like parts.
DETAILED DESCRIPTION OF THE INVENTION
[0021] A general system to which the invention can be applied is
illustrated in FIG. 1. As shown, the HVAC, refrigeration or liquid
chiller system 100 has two compressors incorporated in a
corresponding refrigerant circuit, but it is to be understood that
the system 100 can have more than two compressors for providing the
desired system load. The system 100 includes a first compressor 102
and a second compressor 103 operating in tandem or parallel, a
condenser arrangement 108, expansion devices, a water chiller or
evaporator arrangement 110 and a control panel 112. The control
panel 112 can include an analog to digital (A/D) converter, a
microprocessor, a non-volatile memory, and an interface board to
control operation of the system 100. The control panel 112 receives
input signals from the system 100, e.g., temperature and pressure
measurements, that indicate the performance of the system 100, and
also receives input signals corresponding to the surrounding
ambient conditions, e.g., outdoor air temperature measurements, and
then transmits signals to components of the system 100 to control
the operation of the system 100. The present invention is not
limited to the control panels discussed above and may include any
suitable control system, capable of providing condenser fan
control. A conventional HVAC, refrigeration or liquid chiller
system 100 includes many other features that are not shown in FIG.
1. These features have been purposely omitted to simplify the
drawing for ease of illustration. While the following description
of system 100 is in terms of a HVAC system, it is to be understood
that the invention could be applied to any refrigeration system or
any liquid chiller system.
[0022] The first and second compressors 102 and 103 compress a
refrigerant vapor and deliver it to the condenser arrangement 108
by discharge lines that are combined into a single line. In another
embodiment of the present invention, separate discharge lines are
used to deliver refrigerant vapor to the condenser arrangement 108,
where the refrigerant vapor is combined. The first and second
compressors 102 and 103 are preferably screw compressors or
centrifugal compressors, however the compressors can be any
suitable type of compressor including reciprocating compressors,
scroll compressors, rotary compressors or other type of compressor.
The refrigerant vapor delivered to the condenser 108 enters into a
heat exchange relationship with a fluid, which is preferably air,
and undergoes a phase change to a refrigerant liquid as a result of
the heat exchange relationship with the fluid. The condensed liquid
refrigerant from condenser arrangement 108 flows through
corresponding expansion devices to an evaporator 110.
[0023] The refrigerant liquid delivered to the evaporator 110
enters into a heat exchange relationship with a fluid, e.g., air,
water or secondary liquid, and undergoes a phase change to a
refrigerant gas as a result of the heat exchange relationship with
the fluid. The evaporator 110 can include connections for a supply
line and a return line of the fluid. The fluid travels into the
evaporator 110 via the return line and exits the evaporator 110 via
the supply line. The liquid refrigerant in the evaporator 110
enters into a heat exchange relationship with the fluid to remove
heat from the fluid. The vapor refrigerant in the evaporator 110
then returns to the first and second compressors 102 and 103 to
complete the cycle. The vapor refrigerant in the evaporator 110 can
be combined into a single line exiting the evaporator 110 that then
splits or branches to deliver refrigerant vapor to the first and
second compressors 102 and 103. In another embodiment of the
present invention, the vapor refrigerant then returns to the first
and second compressors 102 and 103 by separate suction lines to
complete the cycle. It is to be understood that any suitable
configuration of evaporator 110 can be used in the system 100,
provided that the appropriate phase change of the refrigerant in
the evaporator 110 is obtained.
[0024] To drive the first and second compressors 102 and 103, the
system 100 includes a motor or drive mechanism for the first and
second compressors 102 and 103. While the term "motor" is used with
respect to the drive mechanism for the first and second compressors
102 and 103, it is to be understood that the term "motor" is not
limited to a motor, but is intended to encompass any component that
can be used in conjunction with the driving of motor, such as a
variable speed drive and a motor starter. In a preferred embodiment
of the present invention, the motor or drive mechanism is an
electric motor and associated components. However, other drive
mechanisms, such as steam or gas turbines or engines and associated
components can be used to drive the first and second compressors
102 and 103.
[0025] FIG. 2 illustrates schematically the condenser arrangement
108 of the present invention. The condenser arrangement 108
includes a condenser coil 202 disposed in a housing 204. The
refrigerant vapor delivered to the condenser coil 202 enters
through an coil inlet connection 220 and the condensed liquid
refrigerant exiting the condenser coil 202 flows through a coil
outlet connection 222. The condenser coil 202 can be any suitable
type of coil arrangement that may be used for providing heat
transfer with a circulating air or gas that passes through the coil
and is preferably sized to accommodate the maximum output capacity
of the first and second compressors 102 and 103. In addition, the
condenser arrangement 108 includes first fan 231, second fan 233,
third fan 235, fourth fan 237 and fifth fan 239 mounted in the
housing 204. The first through fifth fans 231, 233, 235, 237 and
239 are positioned substantially transverse to the condenser coil
202 to draw air substantially perpendicularly through a face 240 of
condenser coil 202. The substantially perpendicular flow of air
through the condenser coil 202 permits the air to enter into a heat
exchange relationship with the refrigerant in the condenser coil
202. In addition, while FIG. 2 illustrates 5 fans, it is to be
understood that as few as 3 fans may be used and that as many as 10
or more fans could be used. While FIG. 2 shows the first through
fifth fans 231, 233, 235, 237 and 239 mounted in the housing 204,
it is to be understood that the first through fifth fans 231, 233,
235, 237 and 239 may be mounted in any suitable manner such that
air is drawn through the coil 202 flows in a substantial
perpendicular manner to face 240 of condenser coil 202.
[0026] The condenser arrangement 108 also includes a baffle 206
positioned between the fourth and fifth fans 237 and 239. "Baffle"
as used herein includes a barrier having a structure configured to
substantially prevent flow of air through the baffle and capable of
channeling air in a direction from coil 202. Baffle 206 extends
from the coil 202 towards the fourth and fifth fans 237 and 239 for
a sufficient length to form a constant or fixed flow channel 210
for airflow between the baffle 206 and the housing 204. "Constant
flow" as used herein indicates that the flow of air through channel
210 is substantially constant when the fifth fan 239 is operating,
i.e., the flow of air in channel 210 is either occurring at a
substantially constant rate based on operation of fifth fan 239 or
no flow is occurring. Airflow through channel 210 and the channeled
portion 242 of the condenser coil 202 corresponding to the channel
210 is isolated from the airflow through the remainder of the
condenser arrangement 108, if any, by baffle 206. In addition, for
channel 210, the flow of air through the channeled portion 242 of
condenser coil 202 is substantially equal to the flow of air from
the channel 210. In other words, the flow of air in channel 210 is
limited to a single direction with a single entrance and single
exit. The arrangement of channel 210 in this embodiment results in
a substantially constant ratio of airflow to condenser coil surface
area. For example, in the embodiment shown in FIG. 2, the airflow
drawn when fifth fan 239 is operating passes through about 1/5 of
the coil surface area condenser. Although FIG. 2 includes a single
fifth fan 239 in channel 210, the present invention may include a
plurality of fans within channel 210, provided that the fans are
all activated and deactivated together or simultaneously.
[0027] In addition to channel 210, the present invention further
includes a variable flow channel 211, which draws air from mixed
airflow portion 244 of the condenser coil 202. "Variable flow" as
used herein indicates that flow in the channel 211 may be varied by
selective activation and/or deactivation of one or more of the
first through fourth fans 231, 233, 235 and 237 disposed in the
channel 211. Unlike the constant flow channel 210, which provides a
predetermined fraction or substantially constant ratio of airflow
to condenser coil surface area, the variable flow channel 211
allows the fraction of airflow to be based upon the combination of
fans activated or deactivated within the variable flow channel 211.
Channel 211 includes the first through fourth fans 231, 233, 235
and 237, each of which are independently controlled and operated.
Further, one or more of the first through fourth fans 231, 233, 235
and 237 may be deactivated, permitting air to enter channel 211
from the area of the deactivated fan(s) to provide a mixed airflow
exiting channel 211. In an alternate embodiment of the invention,
first through fourth fans 231, 233, 235 and 237 each include a
plurality of fans, such as fan pairs, which may be dependently or
independently activated and deactivated with the first through
fourth fans 231, 233, 235 and 237. The mixed airflow includes a
mixture of air drawn through the coil 202 and air drawn into
channel 211 from the areas of the one or more deactivated fans (see
e.g. FIGS. 4-6). Although FIG. 2 shows a constant flow channel 210
and a variable flow channel 211, in an alternate embodiment of the
invention, the condenser arrangement 108 includes a plurality of
variable flow channels 211, wherein the condenser arrangement 108
does not include a constant flow channel 210. In still another
embodiment of the invention, the condenser arrangement 108 includes
a plurality of variable flow channels 211, wherein the condenser
arrangement 108 includes one or more constant flow channels
210.
[0028] FIG. 3 shows the condenser arrangement 108 operating
according to an embodiment of the invention. FIG. 3 shows each of
the first through fifth fans 231, 233, 235, 237 and 239 being
activated to provide a maximum airflow through condenser coil 202.
The airflow through channel 210 includes airflow provided by fifth
fan 239. The airflow through channel 211 includes airflow provided
by a combination of first through fourth fans 231, 233, 235 and
237. When desirable to provide maximum airflow through the
condenser coil 202, such as at times of higher ambient temperatures
and/or during times of higher cooling requirements at the
evaporator, each of the first through fifth fans 231, 233, 235, 237
and 239 may be activated. Inlet air 301 is drawn through the
condenser coil 202 into the condenser arrangement 108 and into
channels 211 and 210. The heated air 303 present in channels 210
and 211 is drawn by the first through fifth fans 231, 233, 235, 237
and 239 and are exhausted from condenser arrangement 108 as exhaust
air 305.
[0029] FIG. 4 shows the condenser arrangement 108 operating
according to another embodiment of the invention. FIG. 4 shows the
first and fifth fans 231 and 239 activated and the second through
the fourth fans 233, 235 and 237 inactivated. The combination of
activated and inactivated fans provides for a mixture of air within
channel 211. As in FIG. 3, airflow through channel 210 includes
airflow provided by the fifth fan 239. However, in FIG. 4, airflow
through channel 211 includes airflow provided by the first fan 231
only. Exhaust air 305 from fan 231 includes a mixture of heated air
303 drawn through the coil 202 and bypass or supplemental air 307,
which is drawn from an exterior area of the condenser arrangement
108 through the areas of the deactivated second through fourth fans
233, 235 and 237. The operation shown in FIG. 4 includes the method
for controlling the refrigerant conditions within the condenser
coil 202 when the ambient temperature is low or the heat load on
the system is reduced. One benefit of this arrangement is that a
substantially quantity of air exhausted from channel 211 by the
first fan 231 is now drawn through the condenser coil 202 and a
reduced amount of air is used to remove heat from the system
100.
[0030] FIG. 5 shows the condenser arrangement 108 operating
according to still another embodiment of the invention. FIG. 5
shows the first, second and fifth fans 231, 233 and 239 activated
and the third and fourth fans 235 and 237 inactivated. The
combination of activated and inactivated fans provides for a
mixture of air within channel 211. As in FIG. 3, airflow through
channel 210 includes airflow provided by the fifth fan 239.
However, in FIG. 5, airflow through channel 211 includes airflow
provided by the first and second fans 231 and 233. Exhaust air 305
from fans 231 and 233 include a mixture of heated air 303 drawn
through the condenser coil 202 and bypass air 307, which is drawn
from an exterior area of the condenser arrangement 108 through the
areas of the deactivated third and fourth fans 235 and 237. The
operation shown in FIG. 5 includes the method for controlling the
refrigerant conditions within the condenser coil 202 when the
ambient temperature is low or the heat load on the system is
reduced.
[0031] FIG. 6 shows the condenser arrangement 108 operating
according to still another embodiment of the invention. FIG. 6
shows the first through third and fifth fans 231, 233, 235 and 239
activated and the fourth fan 237 inactivated. The combination of
activated and inactivated fans provides for a mixture of air within
channel 211. As in FIG. 3, airflow through channel 210 includes
airflow provided by the fifth fan 239. However, in FIG. 6, airflow
through channel 211 includes airflow provided by the first through
third fans 231, 233 and 235. Exhaust air 305 from the first through
third fans 231, 233 and 235 include a mixture of heated air 303
drawn through the condenser coil 202 and bypass air 307, which is
drawn from an exterior area of the condenser arrangement 108
through the areas of the deactivated fourth fan 237. The operation
shown in FIG. 6 includes the method for controlling the refrigerant
conditions within the condenser coil 202 when the ambient
temperature is low or the heat load on the system 100 is
reduced.
[0032] FIG. 7 shown an alternate embodiment of the present
invention including a second baffle 208 can be positioned between
the third and fourth fans 235 and 237. The second baffle 208
extends from the coil 202 towards the third and fourth fans 235 and
237 to form a channel 212 for airflow between the first baffle 206,
the second baffle 208 and the housing 204. Airflow through the
channel 212 and the portion of the condenser coil 202 corresponding
to the channel 212 is isolated from the airflow through the
remainder of the condenser arrangement 108, if any, and is
controlled by the operation of the fourth fan 237. Like with the
arrangement of channel 210 and first baffle 206, second baffle 208
is configured to substantially prevent any airflow through the
channel 212 when the fourth fan 237 is deactivated. Also, like
channel 210 described above, channel 212 may include a plurality of
fans. Although FIGS. 2-7 show embodiments with the first or second
baffles 206 and/or 208, any number of baffles may be used provided
that at least one channel formed by the baffles include a plurality
of fans. Further, although the condenser arrangement 108 shown in
FIG. 7 includes channels 211, 212 and 210, wherein channel 211 is
the only channel subject to variable airflows through the condenser
coil 202, any combination of variable flow channels, such as
channel 211 and constant flow channels, such as channels 210 and
212 may be utilized with the invention. Further still, the
arrangement of fans and channels are not limited to the geometry
shown in FIGS. 2-7, but may include any geometry and arrangement of
fans that provides an airflow through the coil, and having a
combination of constant flow channels and variable flow
channels.
[0033] In addition to the positioning of the first baffle 206,
and/or second baffle 208, the first through fifth fans 231, 233,
235, 237 and 239 may be controlled by the control panel 112 to
generate a desired condenser temperature and/or condenser pressure
when the condenser arrangement is operated at lower ambient
conditions and lower load conditions. A reduction in outdoor
ambient temperature and/or a decrease in system load reduces the
number of the first through fifth condenser fans 231, 233, 235, 237
and 239 that remain activated by the control panel 112.
[0034] In one embodiment of the invention, the control panel 112
executes a control system that preferably uses control algorithm(s)
or software to control operation of the system 100 and to determine
and implement an operating configuration for the first through
fifth fans 231, 233, 235, 237 and/or 239 of the condenser
arrangement 108 to control the condenser temperature and/or
condenser pressure. The control algorithm(s) may include computer
programs or software stored in the non-volatile memory of the
control panel and can include a series of instructions executable
by the microprocessor of the control panel. While it is preferred
that the control algorithm be embodied in a computer program(s) and
executed by the microprocessor, it is to be understood that the
control algorithm may be implemented and executed using digital
and/or analog hardware by those skilled in the art. If hardware is
used to execute the control algorithm, the corresponding
configuration of the control panel can be changed to incorporate
the necessary components and to remove any components that may no
longer be required.
[0035] The control algorithm may sense system parameters and/or
system conditions to generate the appropriate control signals for
the first through fifth fans 231, 233, 235, 237 and/or 239 to
obtain a desired condenser temperature and/or condenser pressure.
Conditions sensed may include, but are not limited to refrigerant
pressure, refrigerant temperature, inlet air temperature, outlet
air temperature, or combinations thereof. For example, a
predetermined set of conditions may allow the control algorithm to
determine that the fifth fan 239 should be operated and the
remaining first through fourth fans 231, 233, 235 and 237 should
not be operated because the airflow through the predetermined ratio
of condenser coil 202 resulting from operation of the fifth fan 239
provides the desired condenser temperature and/or condenser
pressure. However, for another set of inputs the control algorithm
may determine that the first fan 231 should be operated and the
second through fifth fans 233, 235, 237 and 239 should not be
operated because the airflow resulting from operation of the first
fan 231 through channel 211 of condenser coil 202 not isolated from
airflow by first baffle 206 provides the desired condenser
temperature and/or condenser pressure. The control algorithm is not
limited to the combinations above and may include any combination
of the first through fifth fans 231, 233, 235, 237 and /or 239 to
obtain the desired condenser coil temperature and/or condenser
pressure.
[0036] In one embodiment of the invention, the control of the
condenser arrangement 108 may include sensing an ambient
temperature and utilizing a lookup table or similar control scheme
that contains a predetermined combination of fans that corresponds
to the ambient temperature sensed. For example, if the ambient
temperature is between 15.degree. F. and 25.degree. F., the control
panel 112 may deactivate fifth fan 239 and activate first fan 231.
In addition, for ambient temperatures between 25.degree. F. and
35.degree. F. the control panel 112 may activate fifth fan 239 and
activate first fan 231.
[0037] In another embodiment of the present invention, the control
of the condenser arrangement may include sensing condensing
pressure with a pressure sensing device, such as a pressure
transducer, and providing a predetermined combination of fans
corresponding to a condensing pressure range for a lookup table or
similar control scheme. For example, if the pressure falls below a
minimum pressure in a particular capacity step range, the
combination of fans corresponding to the lower capacity are
activated. Likewise, if the pressure rises above a maximum pressure
in a particular capacity step range, the combination of fans
corresponding to the higher capacity are activated.
[0038] While the invention has been described with reference to a
preferred embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
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