U.S. patent application number 12/040697 was filed with the patent office on 2008-06-26 for multi-function multichannel heat exchanger.
This patent application is currently assigned to JOHNSON CONTROLS TECHNOLOGY COMPANY. Invention is credited to Mahesh Valiya-Naduvath, Mustafa K. Yanik.
Application Number | 20080148746 12/040697 |
Document ID | / |
Family ID | 39276218 |
Filed Date | 2008-06-26 |
United States Patent
Application |
20080148746 |
Kind Code |
A1 |
Yanik; Mustafa K. ; et
al. |
June 26, 2008 |
Multi-Function Multichannel Heat Exchanger
Abstract
Heating, ventilation, air conditioning, and refrigeration
(HVAC&R) systems and heat exchangers are provided which contain
integrated auxiliary cooling loops. The heat exchangers include
multiple sets of multichannel tubes located on independent closed
refrigeration loops. One closed loop functions as the main
refrigeration loop of the system while another closed loop provides
auxiliary cooling to system components. The closed loops are
contained within the same heat exchanger, thus, allowing the
auxiliary cooling loop to be integrated into an existing
system.
Inventors: |
Yanik; Mustafa K.; (York,
PA) ; Valiya-Naduvath; Mahesh; (Lutherville,
MD) |
Correspondence
Address: |
Johnson Controls, Inc.;c/o Fletcher Yoder PC
P.O. Box 692289
Houston
TX
77269
US
|
Assignee: |
JOHNSON CONTROLS TECHNOLOGY
COMPANY
Holland
MI
|
Family ID: |
39276218 |
Appl. No.: |
12/040697 |
Filed: |
February 29, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/US07/85277 |
Nov 20, 2007 |
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12040697 |
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60951599 |
Jul 24, 2007 |
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60914589 |
Apr 27, 2007 |
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60882033 |
Dec 27, 2006 |
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60867043 |
Nov 22, 2006 |
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Current U.S.
Class: |
62/115 ; 165/174;
62/498 |
Current CPC
Class: |
F28D 2021/0071 20130101;
F25B 39/00 20130101; F28D 1/05391 20130101; F25B 31/004 20130101;
F28F 2009/0287 20130101; F24F 2221/36 20130101; F28D 1/0443
20130101; F28D 2021/007 20130101 |
Class at
Publication: |
62/115 ; 62/498;
165/174 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F28F 9/02 20060101 F28F009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 20, 2007 |
US |
PCT/US07/85277 |
Claims
1. A heating, ventilating, air conditioning or refrigeration system
comprising: a compressor configured to compress a gaseous
refrigerant; a condenser configured to receive and to condense the
compressed refrigerant; an expansion device configured to reduce
pressure of the condensed refrigerant; and an evaporator configured
to evaporate the refrigerant prior to returning the refrigerant to
the compressor; wherein at least one of the condenser and the
evaporator includes a heat exchanger comprising a first manifold, a
second manifold, a first baffle separating the first manifold into
a first side and a second side, a second baffle separating the
second manifold into a first side and a second side, a first
plurality of multichannel tubes in fluid communication with the
first side of the first manifold and with the first side of the
second manifold, and a second plurality of multichannel tubes in
fluid communication with the second side of the first manifold and
the second side of the second manifold.
2. The system of claim 1, wherein the first plurality of
multichannel tubes receives the refrigerant, and the second
plurality of multichannel tubes receives a fluid other than the
refrigerant.
3. The system of claim 2, wherein the second plurality of
multichannel tubes receives a lubricant from the compressor.
4. The system of claim 2, wherein the second plurality of
multichannel tubes receives a cooling fluid from a power electronic
circuit.
5. The system of claim 4, wherein the power electronic circuit is
part of a variable speed drive providing drive signals to a motor
coupled to the compressor.
6. The system of claim 1, wherein the tubes of the first and second
pluralities of multichannel tubes are substantially identical.
7. A heating, ventilating, air conditioning or refrigeration system
comprising: a compressor configured to compress a gaseous
refrigerant; a condenser configured to receive and to condense the
compressed refrigerant; an expansion device configured to reduce
pressure of the condensed refrigerant; and an evaporator configured
to evaporate the refrigerant prior to returning the refrigerant to
the compressor; wherein at least one of the compressor and the
evaporator includes a heat exchanger having multiple fluid
separated sets of multichannel tubes, one set of multichannel tubes
receiving the refrigerant, and another set of multichannel tubes
receiving another system fluid that is heated or cooled in the heat
exchanger.
8. The system of claim 7, wherein the heat exchanger includes two
fluid separated sets of multichannel tubes.
9. The system of claim 7, wherein the other system fluid is a
lubricant from the compressor.
10. The system of claim 7, wherein the other system fluid is a
cooling fluid from a power electronic circuit.
11. The system of claim 10, wherein the power electronic circuit is
part of a variable speed drive providing drive signals to a motor
coupled to the compressor.
12. The system of claim 7, wherein at least one of the condenser
and the evaporator includes multiple heat exchangers each having
multiple fluid separated sets of multichannel tubes.
13. The heat exchanger of claim 7, wherein the tubes of the first
and second pluralities of multichannel tubes are substantially
identical.
14. A heat exchanger comprising: a first manifold; a second
manifold; a first baffle separating the first manifold into a first
side and a second side; a second baffle separating the second
manifold into a first side and a second side; a first plurality of
multichannel tubes in fluid communication with the first side of
the first manifold and with the first side of the second manifold;
and a second plurality of multichannel tubes in fluid communication
with the second side of the first manifold and the second side of
the second manifold.
15. The heat exchanger of claim 14, wherein at least one of the
first and second manifolds includes an additional baffle to direct
flow in multiple passes through one of the first or second
plurality of multichannel tubes.
16. A method for operating a heating, ventilating, air conditioning
or refrigeration system comprising: circulating a refrigerant in a
closed loop including a condenser and an evaporator, at least one
of the compressor and the evaporator including a heat exchanger
having multiple fluid separated sets of multichannel tubes, one set
of multichannel tubes receiving the refrigerant; circulating
another system fluid other than the refrigerant through another of
the fluid separated sets of multichannel tubes.
17. The method of claim 16, wherein the other system fluid is a
lubricant from a refrigerant compressor.
18. The method of claim 16, wherein the other system fluid is a
cooling fluid from a power electronic circuit.
19. The method of claim 18, wherein the power electronic circuit is
part of a variable speed drive providing drive signals to a motor
coupled to a refrigerant compressor.
20. A heating, ventilating, air conditioning or refrigeration
system comprising: a compressor configured to compress a gaseous
refrigerant; a condenser configured to receive and to condense the
compressed refrigerant; an expansion device configured to reduce
pressure of the condensed refrigerant; an evaporator configured to
evaporate the refrigerant prior to returning the refrigerant to the
compressor; a fan configured to draw cooling air across the
condenser; and an auxiliary heat exchanger section disposed
adjacent to the condenser and cooled by the condenser fan for
cooling a fluid other than the refrigerant.
21. The system of claim 20, wherein the other system fluid is a
lubricant from the compressor.
22. The system of claim 20, wherein the other system fluid is a
cooling fluid from a power electronic circuit.
23. The system of claim 22, wherein the power electronic circuit is
part of a variable speed drive providing drive signals to a motor
coupled to the compressor.
24. The system of claim 20, wherein at least one of the condenser,
the evaporator and the auxiliary heat exchanger includes a
plurality of multichannel tubes.
25. The system of claim 20, wherein the auxiliary heat exchanger
shares a common manifold with the condenser, and the common
manifold includes a baffle to separate a flow of refrigerant from a
flow of the fluid other than refrigerant.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from and the benefit of
U.S. Provisional Application Ser. No. 60/867,043, entitled
MICROCHANNEL HEAT EXCHANGER APPLICATIONS, filed Nov. 22, 2006, U.S.
Provisional Application Ser. No. 60/882,033, entitled MICROCHANNEL
HEAT EXCHANGER APPLICATIONS, filed Dec. 27, 2006, U.S. Provisional
Application Ser. No. 60/914,589, entitled SYSTEMS AND METHODS FOR
REFRIGERANT DISTRIBUTION, filed Apr. 27, 2007, and U.S. Provisional
Application Ser. No. 60/951,599, entitled EFFECTIVE AUXILIARY
COOLING SYSTEMS FOR MODULAR AIR-COOLED CHILLERS, filed Jul. 24,
2007, which are hereby incorporated by reference.
BACKGROUND
[0002] The invention relates generally to multichannel heat
exchangers.
[0003] Heat exchangers are used in heating, ventilation, air
conditioning, and refrigeration (HVAC&R) systems. Multichannel
heat exchangers generally include multichannel tubes for flowing
refrigerant through the heat exchanger. Each multichannel tube may
contain several individual flow channels. Fins may be positioned
between the tubes to facilitate heat transfer between refrigerant
contained within the tube flow channels and external air passing
over the tubes. Multichannel heat exchangers may be used in small
tonnage systems, such as residential systems, or in large tonnage
systems, such as industrial chiller systems.
[0004] In general, heat exchangers transfer heat by circulating a
refrigerant through a cycle of evaporation and condensation.
Chiller systems use heat exchangers to provide cooled air or liquid
to a conditioned space. In many systems, components that are not in
the conditioned space require cooling. For example, the compressor,
which drives the refrigeration cycle, may require cooling,
especially if the compressor utilizes an oil separator. In another
example, the variable speed drive, which powers the compressor
motor, may require cooling of its heat generating components, such
as transistors, inductors, and resistors. The process of removing
heat from these components is referred to as auxiliary cooling. The
auxiliary cooling may be provided by ambient air, refrigerant, oil,
chilled water, or another suitable fluid.
[0005] In general, refrigeration systems use a closed refrigeration
loop for circulating the refrigerant through a cycle of evaporation
and condensation. However, in order to provide auxiliary cooling, a
second closed refrigeration loop with its own heat exchangers may
be needed. The second closed refrigeration loop may require
additional mechanical space for the equipment and piping, and its
integration may pose design and manufacturing challenges. For
example, existing chiller systems may need to be redesigned to
integrate an auxiliary cooling system.
SUMMARY
[0006] In accordance with aspects of the invention, a heating,
ventilating, air conditioning, or refrigeration system is presented
that includes a compressor configured to compress a gaseous
refrigerant, a condenser configured to receive and to condense the
compressed refrigerant, an expansion device configured to reduce
pressure of the condensed refrigerant, and an evaporator configured
to evaporate the refrigerant prior to returning the refrigerant to
the compressor. At least one of the condenser and the evaporator
includes a heat exchanger with a first manifold, a second manifold,
a first baffle, a second baffle, a first plurality of multichannel
tubes, and a second plurality of multichannel tubes. The first
baffle separates the first manifold into a first side and a second
side, and the second baffle separates the second manifold into a
first side and a second side. The first plurality of tubes is in
fluid communication with the first side of the first manifold and
with the first side of the second manifold. The second plurality of
tubes is in fluid communication with the second side of the first
manifold and the second side of the second manifold.
[0007] In accordance with further aspects of the invention a
heating, ventilating, air conditioning, or refrigeration system is
presented that includes a compressor configured to compress a
gaseous refrigerant, a condenser configured to receive and to
condense the compressed refrigerant, an expansion device configured
to reduce pressure of the condensed refrigerant, and an evaporator
configured to evaporate the refrigerant prior to returning the
refrigerant to the compressor. At least one of the compressor and
the evaporator includes a heat exchanger with multiple fluid
separated sets of multichannel tubes. One set of tubes receives the
refrigerant and another set of tubes receives another system fluid
that is heated or cooled in the heat exchanger.
[0008] In accordance with yet further aspects of the invention, a
method for operating a heating, ventilating, air conditioning, or
refrigeration system is provided. The method includes circulating a
refrigerant in a closed loop including a condenser and an
evaporator and circulating another system fluid other than the
refrigerant. At least one of the compressor and the evaporator
include a heat exchanger with multiple fluid separated sets of
multichannel tubes. One set of multichannel tubes receives the
refrigerant and another set of multichannel tubes circulates the
system fluid other than the refrigerant.
DRAWINGS
[0009] FIG. 1 is a perspective view of an exemplary commercial or
industrial HVAC&R system that employs a chiller and air
handlers to cool a building and that may also employ heat
exchangers.
[0010] FIG. 2 is a diagrammatical overview of an exemplary chiller
system which may employ one or more heat exchangers containing
auxiliary cooling tubes.
[0011] FIG. 3 is a perspective view of an exemplary heat exchanger
containing auxiliary cooling tubes.
[0012] FIG. 4 is a detail perspective view of the heat exchanger of
FIG. 3 sectioned through the multichannel tubes.
[0013] FIG. 5 is a perspective view of an exemplary chiller system
which may employ one or more heat exchangers containing auxiliary
cooling tubes.
[0014] FIG. 6 is a right elevational view of the chiller system
shown in FIG. 5 which shows an exemplary coil configuration.
[0015] FIG. 7 is a right elevational view of the chiller system
shown in FIG. 5 which shows another exemplary coil
configuration.
[0016] FIG. 8 is a right elevational view of the chiller system
shown in FIG. 5 which shows yet another exemplary coil
configuration.
[0017] FIG. 9 is a right elevational view of the chiller system
shown in FIG. 5 which shows still another exemplary coil
configuration.
[0018] FIG. 10 is a right elevational view of the chiller system
shown in FIG. 5 which shows a further exemplary coil
configuration.
[0019] FIG. 11 is a right elevational view of the chiller system
shown in FIG. 5 which shows a still further exemplary coil
configuration.
DETAILED DESCRIPTION
[0020] FIG. 1 depicts an exemplary application for multi-function
heat exchangers. Such systems, in general, may be applied in a
range of settings, both within the HVAC&R field and outside of
that field. In presently contemplated applications, however, the
heat exchanges may be used in residential, commercial, light
industrial, industrial and in any other application for heating or
cooling a volume or enclosure, such as a residence, building,
structure, and so forth. Typically, the heat exchanges may be used
in industrial applications, where appropriate, for basic
refrigeration and heating of various fluids.
[0021] FIG. 1 illustrates an application for industrial heating and
cooling, specifically an HVAC&R system for building
environmental management. A building BL is cooled by a system that
includes a chiller CH which is typically disposed on or near the
building, or in an equipment room or basement. Chiller CH is an
air-cooled device that implements a refrigeration cycle to cool
water. The water is circulated to a building through water conduits
WC. Water conduits WC are routed to air handlers AH at individual
floors or sections of the building. Air handlers AH are also
coupled to ductwork DU that is adapted to blow air from an outside
intake OI.
[0022] The chiller, which includes heat exchangers for both
evaporating and condensing a refrigerant as described above, cools
water that is circulated to the air handlers. Air blown over
additional coils that receive the water in the air handlers causes
the water to increase in temperature and the circulated air to
decrease in temperature. The cooled air is then routed to various
locations in the building via additional duct work. Ultimately,
distribution of the air is routed to diffusers that deliver the
cooled air to offices, apartments, hallways, and any other interior
spaces within the building. In many applications, thermostats or
other command devices (not shown in FIG. 1) will serve to control
the flow of air through and from the individual air handlers and
duct work to maintain desired temperatures at various locations in
the structure.
[0023] FIG. 2 illustrates a chiller system 10, which uses
multichannel tubes. Refrigerant flows through system 10 within
closed refrigeration loop 12. The refrigerant may be any fluid that
absorbs and extracts heat. For example, the refrigerant may be
hydrofluorocarbon (HFC) based R-407C, R-22, or R-134a, or it may be
carbon dioxide (R-744a) or ammonia (R-717). Chiller system 10
includes control devices 14, which enable system 10 to cool an
environment to a prescribed temperature.
[0024] System 10 cools an environment by cycling refrigerant within
closed refrigeration loop 12 through a condenser 16, a compressor
18, an expansion device 20, and an evaporator 22. In some
embodiments, the chiller system may include multiple condensers,
compressors, expansions devices, and evaporators, or combinations
thereof. The refrigerant enters condenser 16 as a high pressure and
temperature vapor and flows through the multichannel tubes of
condenser 16. A fan 24, which is driven by a motor 26, draws air
across multichannel tubes. The fan may push or pull air across the
tubes. Heat transfers from the refrigerant vapor to the air
producing heated air 28 and causing the refrigerant vapor to
condense into a liquid. The liquid refrigerant then flows into
expansion device 20 where the refrigerant expands to become a low
pressure and temperature liquid. Typically, the expansion device
will be a thermal expansion valve (TXV); however, in other
embodiments, the expansion device may be an orifice or a capillary
tube. After the refrigerant exits expansion device 20, some vapor
refrigerant may be present in addition to the liquid
refrigerant.
[0025] From expansion device 20, the refrigerant enters evaporator
22 and flows through the evaporator multichannel tubes. A pump 30,
which is driven by a motor 32, draws fluid across the multichannel
tubes. In some embodiments, the pump may be replaced by a fan that
draws air across the multichannel tubes. Heat transfers from the
fluid to the refrigerant liquid producing cooled fluid 34 and
causing the refrigerant liquid to boil into a vapor. The cooled
fluid may be any liquid, but typically may be brine, water, or
water mixed with glycol. The cooled fluid may be used to cool
machinery, lab equipment, ambient air, or other industrial or
commercial applications.
[0026] The refrigerant within closed loop 12 then flows to
compressor 18 as a low pressure and temperature vapor. The
compressor reduces the volume available for the refrigerant vapor,
consequently, increasing the pressure and temperature of the vapor
refrigerant. The compressor may be any suitable compressor such as
a screw compressor, reciprocating compressor, rotary compressor,
swing link compressor, scroll compressor, or turbine compressor. In
one embodiment, the compressor may be a rotary screw compressor
which uses oil for cooling, sealing, and lubricating. The
refrigerant exits compressor 18 as a high temperature and pressure
vapor that is ready to enter the condenser and begin the
refrigeration cycle again.
[0027] Compressor 18 is driven by a motor 36 that receives power
from a variable speed drive (VSD) 38. VSD 38 receives a fixed line
voltage and frequency from an AC power source, varies the voltage
and frequency based on system requirements, and provides the
voltage and frequency to motor 36. The AC power source may be
single phase or multi-phase. Typically, the motor is an induction
motor that may be operated at variable speeds. However, the motor
also may be a switched reluctance (SR) motor, an electronically
commutated permanent magnet motor (ECM), or any other suitable
motor type. In other embodiments, the motor may receive power
directly from an AC or DC power source so that the VSD component is
not used.
[0028] The operation of the refrigeration cycle is governed by
control devices 14 that include control circuitry 40, an input
device 42, and a temperature sensor 44. In some applications, the
input device may be a conventional thermostat. However, the input
device is not limited to thermostats, and more generally, any
source of a fixed or changing set point may be employed. These may
include local or remote command devices, computer systems and
processors, and mechanical, electrical, and electromechanical
devices that manually or automatically set a temperature-related
signal that the system receives. Control circuitry 40 is coupled,
directly or indirectly, to motors 26 and 30, which drive condenser
fan 24 and evaporator pump 30, respectively. Control circuitry 40
is also coupled to VSD 38, which drives the motor for the
compressor. Control circuitry 40 uses information received from
input device 42 and sensor 44 to determine when to operate the
motors 26, 32, and 36 that drive the refrigeration system. The
control system may also send signals to VSD 38 designating the
voltage and frequency to send to motor 36. In some embodiments, the
output speed of the motor may control the output capacity of the
compressor. Other devices may, of course, be included in the
system, such as additional pressure and/or temperature transducers
or switches that sense temperatures and pressures of the
refrigerant, the heat exchangers, the inlet and outlet air, and so
forth.
[0029] For example, in a chiller system, the input device may be a
digital input device that provides a cooled fluid temperature set
point to control circuitry 38. In some embodiments, the input
device may include an interactive LED display capable of receiving
set-points and displaying data such as temperatures, pressures,
electrical values, and past data points. Sensor 42 determines the
current cooled fluid temperature and provides it to control
circuitry 38. Control circuitry 38 then compares the temperature
received from the sensor to the temperature set point received from
the input device. If the temperature is higher than the set point,
the control circuitry may turn on motors 26, 32, and 36 to run
chiller system 10. The control circuitry may execute hardware or
software control algorithms to regulate the air chiller system. In
some embodiments, the control circuitry may include an analog to
digital (A/D) converter, a microprocessor, a non-volatile memory,
and an interface board. Furthermore, the control circuitry and the
VSD may be housed in an electrical control panel in order to
isolate the controls from the outside environment.
[0030] In addition to closed refrigeration loop 12, the chiller
system may also contain a secondary closed loop for providing
auxiliary cooling. The secondary closed loop is independent from
refrigerant loop 12; however, it may share condenser 16 and its fan
24. For example, compressor 18 may use oil for cooling, sealing,
and lubricating. The oil is circulated through the compressor with
the refrigerant and, consequently, becomes heated. A heated oil
flow 46 may be separated from the compressor using a device such as
an oil separator. The oil separator may be an external device or
may be integrated within the refrigeration system. After passing
through the oil separator, heated oil flow 46 may flow within a
closed loop to an auxiliary cooling inlet 48 of the condenser. As
the oil passes through the multichannel coils of condenser 16, the
oil transfers heat to the ambient air that is directed over the
coils by fan 24. Consequently, the oil exiting the auxiliary
cooling condenser outlet 49 is a cooled oil flow 50. Cooled oil
flow 50 is directed through the auxiliary cooling loop back to the
compressor where it may again provide cooling, sealing, and
lubricating.
[0031] In other embodiments, the components of a power electronic
circuit, such as the VSD, may be cooled using the auxiliary cooling
loop. The VSD may contain high power density components used to
store energy and convert power from AC to DC, such as insulated
gate bipolar transistors (IGBT's), silicon controlled rectifiers
(SCR's), and diode rectifiers. The VSD also may contain low power
density components such as inductors resistors, transformers, and
central processing unit chips. The high and low power density
components may require cooling to protect them from heat damage.
Such cooling may be provided by an auxiliary cooling loop
containing an electrical coolant that absorbs and transfers heat
such as water, glycol, refrigerant, ammonia, ethyl chloride, Freon,
CFC's, HFC's, or any other suitable electrical coolant.
[0032] The electrical coolant may be routed through a cooling coil
or chill plate within VSD 38. In some embodiments, a fan may be
included to circulate the air within the VSD enclosure. The
electrical coolant absorbs heat from the components as it flows
through VSD 38. Heated electrical coolant 52 may exit VSD 38
through the auxiliary cooling loop and flow to condenser inlet 48.
As the coolant passes through the multichannel coils of the
condenser 16, the coolant transfers heat to the ambient air that is
directed over the coils by fan 24. Consequently, the coolant
exiting the condenser outlet 49 is cooled electrical coolant 54.
Cooled electrical coolant 54 is directed through the auxiliary
cooling loop and back to VSD 38.
[0033] In some embodiments the auxiliary cooling loop only may be
used to cool the compressor oil. In other embodiments, the
auxiliary cooling loop only may be used to cool the electrical
coolant from the VSD. In yet other embodiments, two or more
auxiliary cooling loops may be provided to cool oil from one or
more compressors, electrical coolant from one or more VSD's, or any
combinations of and electrical coolant thereof. The auxiliary
cooling loop also may be routed through an electrical enclosure
containing the control circuitry to provide cooling for the control
circuitry components. The refrigerant system may have any
combination of a plurality of compressors, condensers, refrigerant
loops, and auxiliary cooling loops.
[0034] FIG. 3. is a perspective view of an exemplary heat exchanger
used in condenser 16. Refrigerant from the closed refrigeration
loop enters a first manifold 56 and flows to a second manifold 58
within refrigeration tubes 60. The refrigerant then returns to
first manifold 56 within refrigeration tubes 60. As the refrigerant
flows between the manifolds, it generally transfers heat to the
ambient air. The refrigerant may change phases as it gives off
heat. For example, as the refrigerant flows to second manifold 58
it may condense into a liquid. Then, as the refrigerant returns to
first manifold 56, the liquid may be subcooled.
[0035] The auxiliary coolant, which may be electrical coolant from
the VSD or oil from the compressor, enters first manifold 56 and
flows to second manifold 58 within auxiliary cooling tubes 62. The
auxiliary cooling tubes may be multichannel tubes or of another
style or configuration (e.g., conventional refrigeration heat
exchanger tubes). As the auxiliary coolant flows through tubes 62,
it transfers heat to the external air. The coolant may condense
from a vapor to a liquid, or the heat transfer may occur within a
single phase, such as cooling a liquid.
[0036] Although 25 refrigerant tubes and 5 auxiliary cooling tubes
are shown in FIG. 4, the number of tubes and tube length within
each section may vary. The manifolds and tubes may be constructed
of aluminum or any other material that allows heat transfer.
Although the tubes are depicted as having an oblong shape in both
the refrigerant and auxiliary cooling sections, the tubes may be
any shape, such as tubes with a cross-section in the form of a
rectangle, square, circle, oval, ellipse, triangle, trapezoid, or
parallelogram. The tube shapes may be the same for both sections,
or each section may have tubes of a different shape. The tube
shapes may vary within a section.
[0037] A baffle 64 separates the fluid flowing to second manifold
58 from the fluid returning from second manifold 58. The
refrigerant typically enters first manifold 56 as a vapor (or a
mixture of vapor and liquid). Baffle 64 directs the vapor
refrigerant toward second manifold 58. As the vapor flows through
tubes 60 it transfers heat to the ambient air flowing across the
tubes, causing it to be de-superheated and to condense to a liquid.
Once the refrigerant reaches second manifold 58, it returns through
the refrigeration tubes back to first manifold 56. As the fluid
returns, the liquid gives off additional heat causing it to be
subcooled.
[0038] A baffle 66, within first manifold 56, separates the fluid
within refrigerant tubes 60 from the fluid within auxiliary cooling
tubes 62. Likewise, a baffle 68, within second manifold 58,
separates these two independent fluids. The baffles may be
constructed of any material that provides a thermal barrier between
the sections. Double baffles may be used to create an internal
volume between the baffles to act as a thermal barrier.
[0039] Although the refrigeration tubes and the auxiliary cooling
tubes are contained within the same heat exchanger, they function
as independent loops. Refrigeration tubes 60 have a refrigerant
inlet 70 which receives refrigerant from the compressor. After
flowing through the heat exchanger, the refrigerant exits through
refrigerant outlet 72 and is directed to the expansion valve of
system 10. The auxiliary cooling tubes have a separate inlet and
outlet separated from the refrigerant tubes by baffles 66 and 68.
Auxiliary cooling tubes 62 receive the cooling fluid through the
cooling fluid inlet 74 from either the compressor or the VSD (or
any other system component in need of heat exchanging
capabilities). After flowing through the tubes and cooling, the
fluid flows out auxiliary cooling outlet 78 and is directed back to
its source, either the VSD or the compressor.
[0040] Fins 80 are located between refrigeration tubes 60 of the
refrigeration section and auxiliary cooling tubes 62 of the
auxiliary cooling section to promote the transfer of heat between
the tubes and the ambient air. However, fins may be eliminated
between the refrigeration section and the auxiliary cooling
section, where desired. In one embodiment, the fins are constructed
of aluminum, brazed to the tubes, and located perpendicular to the
flow of refrigerant. However, in other embodiments, the fins may be
made of other materials that facilitate heat transfer and may
extend parallel to the flow of the refrigerant. The fins may be
louvered fins, corrugated fins, or any other suitable type of fins.
The fin types and materials may vary between the refrigerant
section and the auxiliary cooling section.
[0041] FIG. 4 shows the heat exchanger of FIG. 3 sectioned through
refrigerant tubes 60 to illustrate the internal configuration of
the refrigerant tubes. Refrigerant flows through flow channels 82
contained within tubes 60. The direction of fluid flow 84 is from
manifold 56 shown in FIG. 3 to manifold 58. As the refrigerant
flows toward manifold 58, the refrigerant begins to change phases.
Once the fluid reaches manifold 58, the fluid returns to manifold
56 through other refrigeration tubes 60, not shown in FIG. 4. The
tubes within the refrigeration section may all have the same
internal configuration or different configurations may be used. The
tubes within the auxiliary cooling section may have the same
internal configuration as the refrigerant tubes, or they may have a
different internal configuration such as flow channels with an oval
or square cross-section.
[0042] FIG. 5 is a perspective view of chiller system 10. A frame
88 supports and houses condensers 16, fans 24, other equipment 90,
and a control panel 92. In this embodiment, chiller system 10
contains four condensers; however, other embodiments may contain
any number of condensers. The other equipment may be any equipment
utilized in the chiller system, such as compressors, oil
separators, evaporators, motors, and pumps. Control panel 92
provides access to the input device and control circuitry. In some
embodiments, control panel 92 may house the VSD(s) which run the
compressor motor(s). In these embodiments, the auxiliary cooling
loop may be routed through the control panel to provide cooling to
the VSD components.
[0043] Condensers 16 are positioned adjacent to one another to
support a V-shaped configuration 94 for cooling coils 96. Cooling
coils 96 are inclined from the vertical to form a series of
V-shapes. The fluid flows within cooling coils 96 in a horizontal
direction between manifolds as shown in FIG. 4. The fans draw
ambient air in through the frame to pass over cooling coils 96 and
receive heat from the coils. The V-shaped configuration allows
cooling coils to be added or removed from the refrigeration system
as needed based on capacity. For example, to increase capacity the
number of cooling coils may be increased from the eight cooling
coils shown to twelve cooling coils by adding two additional
modular sections. Typically, each V-shaped section has its own
compressor and dedicated refrigeration closed loop, providing
redundancy in the system. However, the cooling coils of multiple
V-shaped sections may be connected to form larger closed loops.
Each closed loop usually is routed through a shared evaporator;
however, multiple evaporators may be included in some embodiments.
System 10 includes one or more auxiliary cooling loops. Cooling
coils 96 may contain auxiliary cooling sections for these loops as
further illustrated in FIGS. 6 to 11.
[0044] FIG. 6 depicts a side view of chiller system 10 in
accordance with one embodiment. V-shaped configuration 94 includes
eight cooling coils 96, each with an auxiliary cooling section 100
and a refrigerant cooling section 102. In some embodiments, the
auxiliary cooling sections 100 may be connected in series to
provide auxiliary cooling for a single auxiliary cooling loop,
which may be used to cool oil from the compressor or to coil the
VSD components (or other components). Although auxiliary cooling
section 100 is shown at the bottom of the cooling coils, the
auxiliary cooling section may be positioned anywhere along the coil
height. For example, the auxiliary cooling section may be
positioned within tubes that receive less airflow from the
fans.
[0045] In addition to being connected in series, the auxiliary
cooling sections 100 may be connected independently of one another
to form eight individual closed cooling loops which are routed to
separate sections of chiller system 10 to provide auxiliary
cooling. For example, some of the closed cooling loops may be used
to coil oil from compressors, while other closed cooling loops may
be used to cool VSD's. In other embodiments, some of the cooling
sections may be connected in series while others are maintained as
independent loops. Furthermore, in other embodiments, the auxiliary
cooling capacity may be increased or decreased by disconnecting
auxiliary cooling coils. For example, the auxiliary cooling loops
of the rightmost cooling coils 96 may not be connected to any
cooling loops when they are not needed to meet the auxiliary
cooling needs of the system.
[0046] FIG. 7 depicts an alternate coil configuration 104. The
leftmost V-shaped configuration includes dual-function cooling
coils 106 that contain refrigerant cooling sections 108 and
auxiliary cooling sections 110. The auxiliary cooling sections may
be connected in series to provide cooling for one part of the
chiller such as the VSD or the compressor oil. Alternatively, the
auxiliary cooling sections may function as independent loops
directed to different areas of the chiller. The remaining
condensers contain single function cooling coils 112 that provide
refrigerant cooling with refrigerant flowing through all of the
multichannel tubes contained in the coil. Although the
dual-function cooling coils are shown in FIG. 7 as the leftmost
coils, the dual function cooling coils may be located in any one of
the V-shaped configurations. In other embodiments, the system may
contain any number of dual-function cooling coils used within the
V-shaped configurations.
[0047] FIG. 8 depicts another alternate coil configuration 114.
Refrigerant cooling coils 116, without any auxiliary cooling
sections, are used in the generally V-shaped configurations. An
auxiliary cooling coil 118 is located in a horizontal position
between the leftmost refrigerant cooling coils 116. Auxiliary
cooling coil 118 shares a fan 24 with a refrigerant cooling coil
116. In other embodiments, the auxiliary cooling coil may be
positioned at an angle or may have a different geometry such as a
curve or an S-shape. The auxiliary cooling coil also may be located
within any of the V-shaped configurations by substituting the
auxiliary cooling coil for a refrigerant coil. The system may
contain any number of auxiliary cooling coils.
[0048] FIG. 9 illustrates an alternate coil configuration 120 that
uses an independent coil to provide auxiliary cooling. Refrigerant
cooling coils 122 are devoted entirely to refrigerant cooling,
containing no auxiliary cooling sections. An auxiliary cooling coil
124 is located below the refrigerant coils next to equipment 90.
Auxiliary cooling coil 124 has its own fan 126 which draws air over
the auxiliary cooling coil. In other embodiments, the auxiliary
cooling coil may be located at different positions next to the
equipment. The auxiliary cooling coil may be inclined at an angle
or configured in a different geometry such as an S-shape. In other
embodiments, one or more auxiliary cooling coils may be used and
connected in series or independently to form separate loops.
[0049] FIG. 10 depicts an alternate coil configuration 128 that
nests the auxiliary cooling coils within the refrigerant cooling
coils. Refrigerant cooling coils 130 are configured in V-shapes and
the auxiliary cooling coils 132 are nested within one of the
V-shaped configurations. The auxiliary cooling coils may be
positioned at any angle as long as they are contained within the
refrigeration cooling coils 130. The auxiliary cooling coils may be
any geometry that allows air from fan 24 to circulate over both the
refrigeration coils and the auxiliary cooling coils. In other
embodiments, the auxiliary cooling coils may be nested within
multiple V-shaped configurations and connected in series or
independently to form separate loops.
[0050] FIG. 11 illustrates an alternate coil configuration 134 that
uses an independent coil for auxiliary cooling. Refrigerant cooling
coils 136 are configured in V-shapes, and an auxiliary cooling coil
138 is positioned perpendicular to a refrigeration cooling coil
136. Auxiliary cooling coil 138 shares a fan 24 with the
refrigerant cooling coils 136 and is fitted within a V-shaped panel
140 located between refrigeration cooling coils 136. V-shaped
panels 140 generally are metal or similar structures installed
between each set of two coils to prevent air from bypassing
refrigeration cooling coils 136. A portion of panel 140 may be
removed so that auxiliary cooling coil 138 may be fitted within the
panel opening. In other embodiments, one or more auxiliary cooling
coils may be placed in the panels to meet the auxiliary cooling
requirements.
[0051] The coil configurations described herein may find
application in a variety of heat exchangers and HVAC&R systems
containing integrated auxiliary cooling systems. However, the
configurations are particularly well-suited to cooling compressor
oil for a rotary screw compressor used in an industrial chiller.
The configurations are also particularly well-suited to cooling the
variable speed drives (VSD's) used to power compressor motors for
industrial chillers. The coil configurations are intended to
facilitate integration of auxiliary cooling systems within existing
heat exchanger systems.
[0052] It should be noted that the present discussion makes use of
the term "multichannel" tubes or "multichannel heat exchanger" to
refer to arrangements in which heat transfer tubes include a
plurality of flow paths between manifolds that distribute flow to
and collect flow from the tubes. A number of other terms may be
used in the art for similar arrangements. Such alternative terms
might include "microchannel" and "microport." The term
"microchannel" sometimes carries the connotation of tubes having
fluid passages on the order of a micrometer and less. However, in
the present context such terms are not intended to have any
particular higher or lower dimensional threshold. Rather, the term
"multichannel" used to describe and claim embodiments herein is
intended to cover all such sizes. Other terms sometimes used in the
art include "parallel flow" and "brazed aluminum." However, all
such arrangements and structures are intended to be included within
the scope of the term "multichannel." In general, such
"multichannel" tubes will include flow paths disposed along the
width or in a plane of a generally flat, planar tube, although,
again, the invention is not intended to be limited to any
particular geometry unless otherwise specified in the appended
claims.
[0053] While only certain features of the invention have been
illustrated and described herein, many modifications and changes
will occur to those skilled in the art. It is, therefore, to be
understood that the appended claims are intended to cover all such
modifications and changes as fall within the true spirit of the
invention. Furthermore, in an effort to provide a concise
description of the exemplary embodiments, all features of an actual
implementation may not have been described. It should be
appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation specific decisions must be made. Such a development
effort might be complex and time consuming, but would nevertheless
be a routine undertaking of design, fabrication, and manufacture
for those of ordinary skill having the benefit of this
disclosure.
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