Patent Application
20230314052
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Modern residential and industrial customers expect indoor spaces to be climate controlled. In general, heating, ventilation, and air conditioning (“HVAC”) systems circulate an indoor space's air over low-temperature (for cooling) or high-temperature (for heating) sources, thereby adjusting the indoor space's ambient air temperature. HVAC systems generate these low- and high-temperature sources by, among other techniques, taking advantage of a well-known physical principle: a fluid transitioning from gas to liquid releases heat, while a fluid transitioning from liquid to gas absorbs heat. Within a typical HVAC system, a fluid refrigerant circulates through a closed loop of tubing that uses a compressor and other flow-control devices to manipulate the refrigerant's flow and pressure, causing the refrigerant to cycle between the liquid and gas phases. Generally, these phase transitions occur within the HVAC's heat exchangers, which are part of the closed loop and designed to transfer heat between the circulating refrigerant and flowing ambient air.
In some instances, a HVAC system is a split system having indoor and outdoor units, each having a heat exchanger, connected in fluid communication. As would be expected in such cases, the heat exchanger providing heating or cooling to the climate-controlled space or structure is described adjectivally as being “indoors,” and the heat exchanger transferring heat with the surrounding outdoor environment is described as being “outdoors.” The refrigerant circulating between the indoor and outdoor heat exchangers—transitioning between phases along the way—absorbs heat from one location and releases it to the other. Those in the HVAC industry describe this cycle of absorbing and releasing heat as “pumping.” To cool the climate-controlled indoor space, heat is “pumped” from the indoor side to the outdoor side. And the indoor space is heated by doing the opposite, pumping heat from the outdoors to the indoors.
In some other instances, a packaged HVAC system is a self-contained unit including two heat exchangers (e.g., an evaporator coil and a condenser coil), a blower, a compressor, and a refrigerant circuit installed in a shared cabinet. A packaged HVAC system can be installed at any suitable location but is often installed outside, such as on the ground or on the roof of a building. Heated or cooled air is provided from the packaged HVAC system to the indoor space of a building, such as through a supply duct, and air is drawn from the indoor space to the packaged HVAC system, such as through a return duct.
Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.
Certain embodiments of the present disclosure generally relate to refrigerant expansion devices for HVAC systems. More specifically, some embodiments relate to a fixed orifice expansion device having multiple fixed orifices. In one embodiment, a fixed orifice expansion device includes a manifold and a fixed orifice distributor having multiple fixed orifices in a shared body. The multiple fixed orifices are aligned with refrigerant distribution tubes to an evaporator coil. The fixed orifices restrict flow and create pressure drop of refrigerant flowing from the manifold into the refrigerant distribution tubes through the orifices. Different distributors and orifices may be used with the manifold to provide desired pressure drop for refrigerant flowing to the evaporator coil. The fixed orifice expansion device may be installed in a packaged system, a split system, or any other suitable HVAC system.
Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of some embodiments without limitation to the claimed subject matter.
These and other features, aspects, and advantages of certain embodiments will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Specific embodiments of the present disclosure are described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be 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 to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that 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.
When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
By way of example, and turning now to the figures,
Many North American residences, as well as some commercial and industrial buildings, employ “ducted” systems, in which a structure's ambient air is circulated over a central indoor heat exchanger and then routed back through relatively large ducts (or ductwork) to multiple climate-controlled indoor spaces. However, the use of a central heat exchanger can limit the ducted system's ability to vary the temperature of the multiple indoor spaces to meet different occupants' needs. This is often resolved by increasing the number of separate systems within the structure—with each system having its own outdoor unit that takes up space on the structure's property, which may not be available or at a premium.
Some buildings also or instead employ “ductless” systems, in which refrigerant is circulated between an outdoor unit and one or more indoor units to heat and cool specific indoor spaces. Unlike ducted systems, ductless systems route conditioned air to the indoor space directly from the indoor unit—without ductwork.
The described HVAC system 10 of
Focusing on the ducted indoor unit 16, it has an air-handler unit (or AHU) 24 that provides airflow circulation, which in the illustrated embodiment draws ambient indoor air via a return vent 26, passes that air over one or more heating/cooling elements (i.e., sources of heating or cooling), and then routes that conditioned air, whether heated or cooled, back to the various climate-controlled spaces 20 through supply vents 28. As depicted in
As shown, the ducted indoor unit 16 is a “dual-fuel” system that has multiple heating elements. A gas furnace 34, which may be located downstream (in terms of airflow) of the blower 32, combusts natural gas to produce heat in furnace tubes (not shown) that coil through the furnace. These furnace tubes act as a heating element for the ambient indoor air being pushed out of the blower 32, over the furnace tubes, and into supply ducts 30 to supply vents 28. In other instances, the furnace 34 is an electric furnace, with one or more heat strips or other electric heating elements for heating air passing through the AHU 24, rather than a gas furnace. Whether gas or electric, the furnace 34 is generally operated when robust heating is desired. During conventional heating and cooling operations, air from the blower 32 is routed over an indoor heat exchanger 36 and into the supply ducts 30.
The blower 32, furnace 34, and indoor heat exchanger 36 may be packaged as an integrated AHU, or those components may be modular. Moreover, it is envisaged that the positions of the furnace, indoor heat exchanger, and blower can be reversed or rearranged. Internal components of the blower 32, the furnace 34, and the indoor heat exchanger 36 can be positioned within one or more casings, cabinets, or other housings (integrated or modular).
The indoor heat exchanger 36—which in this embodiment for the ducted indoor unit 16 is an A-coil 38 (
In the illustrated embodiment of
The outdoor unit 14 is a side-flow unit that houses, within a plastic or metal casing or housing 50, the various components that manage the refrigerant's flow and pressure. This outdoor unit 14 is described as a side-flow unit because the airflow across the outdoor heat exchanger 42 is motivated by a fan that rotates about an axis that is non-perpendicular with respect to the ground. In contrast, “up-flow” devices generate airflow by rotating a fan about an axis generally perpendicular to the ground. (As illustrated, the Y-axis is perpendicular to the ground.) In one embodiment, the side-flow outdoor unit 14 may have a fan 52 that rotates about an axis that is generally parallel to the ground. (As illustrated, the X- and Z-axes are parallel to the ground.) It is envisaged that either up-flow or side-flow units could be employed. Advantageously, the side-flow outdoor unit 14 provides a smaller footprint than traditional up-flow units, which are more cubic in nature.
In addition to the ducted indoor unit 16, the illustrated HVAC system has ductless indoor units 18 that also circulate refrigerant, via the refrigerant lines 40, between the outdoor heat exchanger 42 and the ductless indoor unit's heat exchanger. The ductless indoor units 18 may work in conjunction with or independent of the ducted indoor unit 16 to heat or cool the given indoor space 20. That is, the given indoor space 20 may be heated or cooled with the structure's air that has been conditioned by the ductless indoor unit 18 and by the air routed through the ductwork 30 after being conditioned by the A-coil 38, or it may be entirely conditioned by the ductless indoor unit or the ducted indoor unit working independent of one another. As another embodiment, the A-coil refrigerant loop may be operated to provide cooling or heating only—and the ductless indoor units may also be designed to provide cooling or heating only.
As is well known, the HVAC system may be in communication with a thermostat 54 that senses the indoor space's temperature and allows the structure occupants to “set” the desired temperature for that sensed indoor space. The thermostat may operate using a simple on/off protocol that sends 24V signals, for example, to the HVAC system to either activate or deactivate various components; or it may be a more complex thermostat that uses a “communicating protocol,” such as ClimateTalk or a proprietary protocol, that sends and receives data signals and can provide more complex operating instructions to the HVAC system.
To cool the structure, the high-pressure gas is routed to the outdoor heat exchangers 42, where airflow generated by the fans 52 aids the transfer of heat from the refrigerant to the environment—causing the refrigerant to condense into a liquid that is at high-pressure. As shown, the outdoor unit 14 has multiple heat exchangers 42 and fans 52 connected in parallel, to aid the HVAC system's operation.
The refrigerant leaving the heat exchangers 42 is or is almost entirely in the liquid state and flows through or bypasses a metering device 74. From there, the high-pressure liquid refrigerant flows into a series of receiver check valves 76 that manage the flow of refrigerant into the receiver 78. The receiver 78 stores refrigerant for use by the system and provides a location where residual high-pressure gaseous refrigerant can transition into liquid form. The receiver may be located within the casing 50 of the outdoor unit or may be external to the casing 50 of the outdoor unit (or the system may have no receiver at all). From the receiver 78, the high-pressure liquid refrigerant flows to the indoor units 16, 18, specifically to metering devices 80 that restrict the flow of refrigerant into each heat exchanger of the indoor units 16, 18, to reduce the refrigerant's pressure. The refrigerant leaves the indoor metering devices 80 as a low-pressure liquid (or mostly liquid). The metering device 80 may take any suitable form. The metering device 80 may be an electronic expansion valve, for instance, but other types of metering devices—like capillaries, thermal expansion valves, pistons, or reduced orifice tubing—are also envisaged. In at least some embodiments, and as described in greater detail below, the metering device 80 is a fixed orifice expansion device (e.g., expansion device 116 of
Low-pressure liquid refrigerant is then routed to the indoor heat exchangers 36. As illustrated, the indoor heat exchanger 36 for the ducted indoor unit 16 is an “A-coil” style heat exchanger 38. But the heat exchanger 38 can be an “N-coil” (or “Z-coil”) style heat exchanger or a slab coil or can take any other suitable form. Airflow generated by the blower 32 aids in the absorption of heat from the flowing air by the refrigerant, causing the refrigerant to transition from a low-pressure liquid to a low-pressure gas as it progresses through the indoor heat exchanger 36. And the airflow generated by the blower 32 drives the now cooled air into the ductwork 30 (specifically the supply ducts), cooling the indoor spaces 20. In a similar fashion, the low-pressure liquid refrigerant is routed to the indoor heat exchangers 36 of the ductless indoor units 18, where it is evaporated, causing the refrigerant to absorb heat from the environment. However, unlike the ducted indoor unit, the ductless indoor units circulate air without ductwork, using a local fan 52, for example.
The refrigerant leaving the indoor heat exchangers 36, which is now entirely or mostly a low-pressure gas, is routed to the reversing valve 64 that directs refrigerant to the accumulator 82. Any remaining liquid in the refrigerant is separated in the accumulator, ensuring that the refrigerant reaching the compressor inlet 70 is almost entirely in a gaseous state. The compressor 46 then repeats the cycle, by compressing the refrigerant and expelling it as a high-pressure gas.
For heating the structure 12, the process is reversed. High-pressure gas is still expelled from the compressor outlet 60 and through the oil separator 66 and flow meter 62. However, for heating, the reversing valve 64 directs the high-pressure gas to the indoor heat exchangers 36. There, the refrigerant—aided by airflow from the blower 32 or the fans 52—transitions from a high-pressure gas to a high-pressure liquid, rejecting heat. And that heat is driven by the airflow from the blower 32 into the ductwork 30 or by the fans 52 in the ductless indoor units 18, heating the indoor spaces 20. If more robust heating is desired, the gas furnace 34 may be ignited, either supplementing or replacing the heat from the heat exchanger. That generated heat is driven into the indoor spaces by the airflow produced by the blower 32. In other instances, electric heating elements (e.g., of an electric furnace 34 of the indoor units 16 or 18) may also or instead be used to provide heat to the indoor spaces 20.
The high-pressure liquid refrigerant leaving each indoor heat exchanger 36 is routed through or past the given metering device 80. Using the refrigerant lines 40, the high-pressure liquid refrigerant is routed to the receiver check valves 76 and into the receiver 78. As described above, the receiver 78 stores liquid refrigerant and allows any refrigerant that may remain in gaseous form to condense. From the receiver, the high-pressure liquid refrigerant is routed to an outdoor metering device 74, which lowers the pressure of the liquid. Like the indoor metering device 80, the illustrated outdoor metering device 74 may take any suitable form. It is envisaged that the outdoor metering device could be any number of devices, including capillaries, electronic expansion valves, thermal expansion valves, pistons, or reduced orifice tubing, for example. In some embodiments, the metering device 74 is a fixed orifice expansion device (e.g., expansion device 116 of
The lower-pressure liquid refrigerant is then routed to the outdoor heat exchangers 42, which are acting as evaporators. That is, the airflow generated by the fans 52 aids the transition of low-pressure liquid refrigerant to a low-pressure gaseous refrigerant, absorbing heat from the outdoor environment in the process. The low-pressure gaseous refrigerant exits the outdoor heat exchanger 42 and is routed to the reversing valve 64, which directs the refrigerant to the accumulator 82. The compressor 46 then draws in gaseous refrigerant from accumulator 82, compresses it, and then expels it via the outlet 60 as high-pressure gas, for the cycle to be repeated.
As illustrated in
In many instances, the structure 12 may have had a previous HVAC system with pre-existing refrigerant piping at least partially built into the structure's interior walls. For example, the pre-existing system may be a traditional HVAC unit that uses circulating refrigerant for cooling only and a gas furnace for heating, with all of the conditioned air delivered to the interior spaces via the ductwork. And the pre-existing refrigerant lines—which are built into the walls of the structure—may have a gas line with a 6/8-inch, ⅞-inch, or 9/8-inch outer diameter gas line. However, in certain embodiments, the outdoor unit 14 may have more modern refrigerant piping, which tends to be smaller in outer diameter. For example, the outdoor unit 14 may be 2-, 3-, or 4-Ton unit that has a gas line diameter of ⅝ inch. It would be laborious and cost ineffective to replace the pre-existing gas line in the structure with ⅝-inch diameter tubing. Accordingly, the illustrated HVAC system includes a coupler 88 that helps couple the varying diameter gas lines to one another. For example, the coupler 88 may facilitate coupling of the outdoor unit's ⅝-inch diameter gas line to the structure's pre-existing 6/8-inch, ⅞-inch, or 9/8-inch diameter gas line. In another embodiment, the outdoor unit 14 may be a 5-Ton unit with a gas line having a diameter of 6/8 inch. The coupler could facilitate coupling of this outdoor unit with a pre-existing gas line of ⅞-inch or 9/8-inch diameter.
In another embodiment depicted in
Heat exchangers 108 and 110 within the cabinet 102 facilitate heat transfer and allow ambient air received through the return duct opening 106 to be treated (e.g., heated or cooled) and supplied to the structure via the supply duct opening 104. The packaged system 100 can include multiple heat exchangers 110, and fan vents 112 facilitate heat transfer and airflow from the cabinet 102 to the surrounding environment. The heat exchanger 108 is an evaporator coil and the heat exchanger 110 is a condenser coil in at least some instances. Like described above with respect to the split system 10, fluid refrigerant is circulated through and between the heat exchangers 108 and 110 to cause the refrigerant to cycle between the liquid and gas phases and transfer heat with ambient air.
It will be appreciated that other components are also installed within the cabinet 102, such as a blower, compressors 114, and tubing for routing the refrigerant between the compressors 114 and the heat exchangers 108 and 110. The blower generates airflow through the heat exchanger 108, which can condition the air via heat transfer, such as described above. Although two compressors 114 are depicted in
Still further, a metering device 116 is shown installed within the cabinet 102 in
An example of the metering device 116 in the form of a fixed orifice expansion device is illustrated in
In at least some instances, the evaporator coil 118 includes multiple refrigerant circuits 124 that are independent of one another in the evaporator coil 118 and that each receive refrigerant from the expansion device 116 through at least one refrigerant distribution tube 122. In
The refrigerant distribution tubes 122 can be connected to the expansion device 116 in any suitable manner. As shown in
The fixed orifice distributor 130 includes fixed orifices 132 in a shared body. The orifices 132 restrict flow of refrigerant (generally referred to by reference numeral 134 in
The fixed orifice distributor 130, which may also be referred to as a flow restrictor 130, can have any suitable shape and configuration. By way of example, the flow restrictor 130 can include a round tube body 136 having the orifices 132, such as shown in
The manifold 120 can receive various flow restrictors with orifices of different shapes and sizes. In
The different sizes of the orifices 132 and 142 will cause different amounts of pressure drop for refrigerant passing through the orifices. The size of an orifice in a flow restrictor is inversely related to the amount of pressure drop of refrigerant passing through that orifice. As such, using the flow restrictor 130 with the smaller orifices 132 will provide a larger pressure drop for refrigerant passing through the orifices than would using the flow restrictor 140 with the larger orifices 142.
As shown in
While the flow restrictors of
As a further example, a flow restrictor 180 is depicted in
Although the flow restrictors of
In still other instances, flow restrictors with orifices may be provided outside of the manifold 120 to restrict flow of refrigerant from the manifold 120 toward the evaporator coil 118 through the orifices. In
Fixed orifice flow restrictors, such as those described above, can include any suitable positioning features to facilitate alignment and installation of the flow restrictors at (e.g., within or on) an evaporator inlet manifold. The positioning features can provide one or both of angular alignment or longitudinal alignment of the flow restrictor and its orifices with respect to the outlets of the evaporator inlet manifold. Examples of positioning features that could be used include keys, slots, holes, guides, other protrusions or indents, or combinations of these or other positioning features. Each positioning feature could be provided on the evaporator inlet manifold or on the flow restrictor in accordance with the present techniques.
By way of example, a portion of the flow restrictor 130 is shown in
Finally, as noted above, the spacings between the flow restrictor orifices and their angular positions within the manifold can be different in some embodiments. For instance, a flow restrictor 130 is shown in
While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
