US20080148746A1

US20080148746A1 - Multi-Function Multichannel Heat Exchanger

Info

Publication number: US20080148746A1
Application number: US12/040,697
Authority: US
Inventors: Mustafa K. Yanik; Mahesh Valiya-Naduvath
Original assignee: Johnson Controls Technology Co
Current assignee: Johnson Controls Technology Co
Priority date: 2006-11-22
Filing date: 2008-02-29
Publication date: 2008-06-26
Also published as: WO2008064247A1

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.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

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

The invention relates generally to multichannel heat exchangers.
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.
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.
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

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.
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.
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

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.

FIG. 2 is a diagrammatical overview of an exemplary chiller system which may employ one or more heat exchangers containing auxiliary cooling tubes.

FIG. 3 is a perspective view of an exemplary heat exchanger containing auxiliary cooling tubes.

FIG. 4 is a detail perspective view of the heat exchanger of FIG. 3 sectioned through the multichannel tubes.

FIG. 5 is a perspective view of an exemplary chiller system which may employ one or more heat exchangers containing auxiliary cooling tubes.

FIG. 6 is a right elevational view of the chiller system shown in FIG. 5 which shows an exemplary coil configuration.

FIG. 7 is a right elevational view of the chiller system shown in FIG. 5 which shows another exemplary coil configuration.

FIG. 8 is a right elevational view of the chiller system shown in FIG. 5 which shows yet another exemplary coil configuration.

FIG. 9 is a right elevational view of the chiller system shown in FIG. 5 which shows still another exemplary coil configuration.

FIG. 10 is a right elevational view of the chiller system shown in FIG. 5 which shows a further exemplary coil configuration.

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

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

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;

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;

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.