The application generally relates to a heat exchanger support and more specifically, to a support for a multichannel heat exchanger in a heating, ventilation, air conditioning and refrigeration (HVAC&R) system.
Multichannel heat exchangers may include a series of tube sections that circulate a fluid, for example, water or refrigerant. The tube sections are physically and thermally connected by fins. The fins permit airflow through the heat exchanger for heat transfer between the airflow and the circulating fluid.
Due to the thermal performance of a multichannel heat exchanger, the multichannel heat exchanger may operate at a low condensing temperature and reduce the temperature differential between the liquid refrigerant and air, thereby resulting in an efficient heat exchanging system.
A multichannel heat exchanger may be susceptible to corrosion when attached directly to a frame composed of dissimilar material, which may reduce the useful life of the multichannel heat exchanger. Separating the multichannel heat exchanger from the frame may reduce the possibility of corrosion.
One embodiment of the present application relates to a heating, ventilation, air conditioning and refrigeration (HVAC&R) system having a compressor, a heat exchanger, an expansion device, and a multichannel heat exchanger connected in a closed refrigerant loop. The system also includes a base for providing support to the multichannel heat exchanger, and at least one body disposed on the base. The at least one body provides support the multichannel heat exchanger and separates the multichannel heat exchanger from the base.
Another embodiment relates to a heating, ventilation, air conditioning and refrigeration (HVAC&R) system having a compressor, a heat exchanger, an expansion device and a multichannel heat exchanger connected in a closed refrigerant loop. The system also includes a base for providing support to the multichannel heat exchanger and at least one body and at least one retainer. The at least one body and at least one retainer are disposed on the base. The at least one body supports the multichannel heat exchanger and separates the multichannel heat exchanger from the base. The at least one retainer substantially prevents a manifold of the multichannel heat exchanger from contacting the base.
Yet another embodiment relates to a heating, ventilation, air conditioning and refrigeration (HVAC&R) system having a compressor, a heat exchanger, an expansion device and a multichannel heat exchanger connected in a closed refrigerant loop. The system also includes a base for providing support to the multichannel heat exchanger and at least one body, at least one retainer, and at least one grommet. The at least one body, at least one retainer, and at least one grommet are disposed on the base. The at least one body supports the multichannel heat exchanger and separates the multichannel heat exchanger from the base. The at least one retainer substantially prevents a manifold of the multichannel heat exchanger from contacting the base. The at least one grommet substantially isolates the multichannel heat exchanger from the base.
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HVAC&R system 10 circulates refrigerant within closed refrigeration loop 60 through a compressor 66, a condenser 64, an electronic expansion device 68, and an evaporator 70. Compressed refrigerant vapor enters condenser 64 and flows through condenser 64. A fan 72, which is driven by a motor 74, circulates air across condenser 64. Fan 72 may push or pull air across condenser 64. The refrigerant vapor exchanges heat with the air 76 and condenses into a liquid. The liquid refrigerant then flows into expansion device 68, which lowers the pressure of the refrigerant. Expansion device 68 may be a thermal expansion valve (TXV) or any other suitable expansion device, orifice or capillary tube. After the refrigerant exits expansion device 68, some vapor refrigerant may be present along with the liquid refrigerant.
From expansion device 68, the refrigerant enters evaporator 70. A fan 78, which is driven by a motor 80, circulates air across evaporator 70. Liquid refrigerant in evaporator 70 absorbs heat from the circulated air and undergoes a phase change to a refrigerant vapor. Fan 78 may be replaced by a pump, which draws fluid across evaporator 70.
The refrigerant vapor then flows to compressor 66. Compressor 66 reduces the volume of the refrigerant vapor and increases the pressure and temperature of the vapor refrigerant. Compressor 66 may be any suitable compressor such as a screw compressor, reciprocating compressor, rotary compressor, swing link compressor, scroll compressor, or turbine compressor. Compressor 66 is driven by a motor 84, which receives power from a variable speed drive (VSD) or an alternating current (AC) or direct current (DC) power source. In an exemplary embodiment, motor 84 receives fixed line voltage and frequency from an AC power source. In some applications, the motor may be driven by a variable voltage or frequency drive. The motor may be a switched reluctance (SR) motor, an induction motor, an electronically commutated permanent magnet motor (ECM), or any other suitable motor type.
The operation of HVAC&R system 10 is controlled by control devices 62. Control devices 62 include control circuitry 86, a sensor 88, and a temperature sensor 90. Control circuitry 86 is coupled to motors 74, 80 and 84, which drive condenser fan 72, evaporator fan 78 and compressor 66, respectively. Control circuitry 86 uses information received from sensor 88 and temperature sensor 90 to determine when to operate motors 74, 80 and 84. For example, in a residential air conditioning system, sensor 88 may be a programmable twenty-four volt thermostat that provides a temperature set point to control circuitry 86. Sensor 90 may determine the ambient air temperature and provide the temperature to control circuitry 86. Control circuitry 86 may compare the temperature value received from the sensor to the temperature set point received from the thermostat. If the temperature value from the sensor is higher than the temperature set point, control circuitry 86 may turn on motors 74, 80 and 84, to operate HVAC&R system 10. Additionally, control circuitry 86 may execute hardware or software control algorithms to regulate HVAC&R system 10. Control circuitry 86 may include an analog to digital (A/D) converter, a microprocessor, a non-volatile memory, and an interface board. Other devices may be included in HVAC&R system 10, 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.
HVAC&R system 10 includes an outdoor coil 96 and an indoor coil 98 that operate as heat exchangers. As noted above, the coils 96 and 98 may function as an evaporator or a condenser depending on the operational mode of HVAC&R system 10. For example, when system 10 is operating in a cooling (or air conditioning) mode, outdoor coil 96 functions as a condenser, releasing heat to the outside air, while indoor coil 98 functions as an evaporator, absorbing heat from the inside air. When HVAC&R system 10 is operating in a heating mode, outdoor coil 96 functions as an evaporator, absorbing heat from the outside air, while indoor coil 98 functions as a condenser, releasing heat to the inside air. A reversing valve 104 is positioned in reversible loop 94 between coils 96 and 98 to control the direction of refrigerant flow from compressor 66 and to switch HVAC&R system 10 between heating mode and cooling mode.
HVAC&R system 10 also includes two metering devices 100 and 102 for decreasing the pressure and temperature of the refrigerant before the refrigerant enters the heat exchanger operating as the evaporator. Metering devices 100 and 102 regulate refrigerant flow into the evaporator so that the amount of refrigerant entering the evaporator equals the amount of refrigerant exiting the evaporator. Metering devices 100 and 102 are used depending on the operational mode of HVAC&R system 10. For example, when HVAC&R system 10 is operating in a cooling mode, metering device 100 does not monitor the refrigerant as the refrigerant flows through metering device 100 and on to metering device 102. Metering device 102 monitors the refrigerant before the refrigerant enters indoor coil 98, which operates as an evaporator. When HVAC&R system 10 is operating in heating mode, metering device 102 does not monitor the refrigerant as the refrigerant flows through metering device 102. Metering device 100 monitors the refrigerant as the refrigerant flows from indoor coil 98 to outdoor coil 96. A single metering device may be used for both heating mode and cooling mode. Metering devices 100 and 102 typically are TXVs, but may be any suitable expansion device, orifice or capillary tubes.
In a heating mode of operation, the evaporator is outdoor coil 96 and in a cooling mode of operation, the evaporator is the indoor coil 98. Vapor refrigerant may be present in the refrigerant as a result of the expansion process that occurs in metering device 100 and 102. The refrigerant flows through the evaporator and absorbs heat from the air and undergoes a phase change into a vapor. In addition, the air passing over the evaporator may be dehumidified. The moisture from the air may be removed by condensing on the outer surface of the tubes. After exiting the evaporator, the refrigerant passes through reversing valve 104 and flows into compressor 66.
From compressor 66, the vapor refrigerant flows into a condenser. In cooling mode of operation, the condenser is the outdoor coil 96, and in the heating more of operation, the condenser is the indoor coil 98. In the cooling mode of operation, a fan 72 is powered by a motor 74 and circulates air over the condenser. The heat from the refrigerant is transferred to the outside air causing the refrigerant to undergo a phase change into a liquid. In heating mode of operation, a fan 78 is powered by a motor 80 and circulates air over the condenser. The heat from the refrigerant is transferred to the inside air causing the refrigerant to undergo a phase change into a liquid.
After exiting the condenser, the refrigerant flows through the metering device (100 in heating mode and 102 in cooling mode) and returns to the evaporator (outdoor coil 96 in heating mode and indoor coil 98 in cooling mode) where the process begins again. In both heating and cooling modes of operation, a motor 106 drives compressor 66 and compressor 66 circulates refrigerant through the reversible loop 94. Motor 106 may receive power either directly from an AC or DC power source or from a VSD.
Operation of motor 106 is controlled by control circuitry 86. Control circuitry 86 receives information from a sensor 88 and sensors 108, 110 and 112 and uses the information to control the operation of HVAC&R system 10 in both cooling mode and heating mode. For example, in cooling mode, sensor 88 may be a thermostat and may provide a temperature set point to control circuitry 86. Sensor 112 measures the ambient indoor air temperature and communicates the indoor air temperature level to control circuitry 86. If the air temperature is above the temperature set point, the HVAC&R system may operate in the cooling mode of operation. Control circuitry 86 may compare the air temperature to the temperature set point and engage compressor motor 106 and fan motors 74 and 80 to operate the HVAC&R system in a cooling mode. If the air temperature is below the temperature set point, the HVAC&R system may operate in the heating mode of operation. Control circuitry 86 may compare the air temperature from sensor 112 to the temperature set point from sensor 88 and engage motors 74, 80 and 106 to operate the HVAC&R system 10 in a heating mode.
Control circuitry 86 may use information received from sensor 88 to switch HVAC&R system 10 between heating mode and cooling mode. For example, if sensor 88 is set to cooling mode, control circuitry 86 may send a signal to a solenoid 82 to place reversing valve 104 in the air conditioning or cooling position. The refrigerant may then flow through reversible loop 94 as follows. The refrigerant exits compressor 66 and flows to outdoor coil 96, which is operating as a condenser. The refrigerant is then expanded by metering device 102, and flow to indoor coil 98, which is operating as an evaporator. If sensor 88 is set to heating mode of operation, control circuitry 86 may send a signal to solenoid 82 to place reversing valve 104 in the heating position. The refrigerant may then flow through reversible loop 94 as follows. The refrigerant exits compressor 66 and flows to indoor coil 98, which is operating as an evaporator. The refrigerant is then expanded by metering device 100, and flows to outdoor coil 96, which is operating as a condenser. Control circuitry 86 may execute hardware or software control algorithms to regulate HVAC&R system 10. Control circuitry 86 may include an A/D converter, a microprocessor, a non-volatile memory, and an interface board.
Control circuitry 86 also may initiate a defrost cycle for outside coil 96 when HVAC&R system 10 is operating in heating mode. When the outdoor temperature approaches freezing, that is, thirty-two deg. F., moisture in the outside air that is directed over outdoor coil 96 may condense and then freeze on the coil. Sensor 108 measures the outside air temperature, and sensor 110 measures the temperature of outdoor coil 96. The temperature information gathered by sensors 108 and 110 are provided to control circuitry 86, which determines when to initiate a defrost cycle for outdoor coil 96. For example, if sensor 108 or sensor 110 provides a temperature below freezing to the control circuitry, system 10 may initiate a defrost cycle for outdoor coil 96. In a defrost cycle, solenoid 82 is actuated to place reversing valve 104 to air conditioning position, and motor 74 is shut off to discontinue airflow over outside coil 96. HVAC&R system 10 operates in cooling mode until the “warm” refrigerant from compressor 66 defrosts outdoor coil 96. Once sensor 110 detects that outdoor coil 96 is defrosted by monitoring a parameter of outdoor coil 96, such as the temperature, control circuitry 86 returns reversing valve 104 to heating position. The defrost cycle may also be set to occur at various predetermined time and temperature combinations with or without relying on sensors 108 and 110.
In some embodiments, the construction of first tubes 128 may differ from the construction of second tubes 130. Tubes 126 may also differ within each section. For example, tubes 126 may all have identical cross sections, or first tubes 128 may be rectangular while second tubes 130 may be oval.
Refrigerant enters multichannel heat exchanger 120 through an inlet 132 and exits multichannel heat exchanger 120 through an outlet 134. Although
Fins 138 are located between multichannel tubes 126 to promote heat transfer between tubes 126 and the environment. Fins 138 may be constructed of aluminum, may be brazed or otherwise joined to tubes 126, and disposed generally perpendicular to the flow of refrigerant. Fins 138 may also be made of other suitable materials that facilitate heat transfer and may extend parallel or at varying angles with respect to the flow of the refrigerant. Fins 138 may be louvered fins, corrugated fins, or any other suitable type of fin.
In an evaporator heat exchanger application, at least a portion of the heat transfer occurs during a phase change of the refrigerant. Refrigerant exits expansion device 68 (see, for example,
In
Block 140 has a pair of projections, such as feet 150, extending away from the underside 152 of interior surface 146. Projections or feet 150 are located on opposite sides 148 of block 140, and define a passageway 154 for draining liquid accumulating along base 142. Passageway 154 may have a semi-circular shape, or any other suitable shape for draining accumulated liquid from the base 142. Feet 150 may have a shape similar to an “L”, as shown in the figures. Feet 150 may have any suitable shape. Block 140 provides a vertical spacing between base 142 and multichannel heat exchanger 120. Feet 150 may have a textured bottom for providing a friction surface to prevent slipping or movement of the feet when multichannel heat exchanger 120 is in place.
Block 140 may be manufactured from rubber or any other suitable elastomeric and non-conductive material. Block 140 can provide electrical isolation between multichannel heat exchanger 120 and base 142. The electrical isolation reduces and/or eliminates the susceptibility of multichannel heat exchanger 120 to corrosion caused by circulating currents in base 142. Block 140 raises multichannel heat exchanger 120 to provide a drainage space for liquid from multichannel heat exchanger 120. Block 140 may include one or more tabs (not shown). The tabs may be inserted into corresponding slots (not shown) in base 142, multichannel heat exchanger 120, or both, to hold block 140 in position.
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While only certain features and embodiments of the invention have been illustrated and described, many modifications and changes may occur to those skilled in the art (for example, variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (for example, temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. 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 (that is, those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the claimed invention). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may 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, without undue experimentation.
This application claims priority from and the benefit of U.S. Provisional Application No. 60/952,280, entitled MICROCHANNEL HEAT EXCHANGER APPLICATIONS, filed on Jul. 27, 2007, which is hereby incorporated by reference in its entirety into this application.
Number | Date | Country | |
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60952280 | Jul 2007 | US |