Patent Application
20230258349
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, commercial, and industrial customers expect indoor spaces to be climate controlled. Heating, ventilation, and air conditioning (“HVAC”) systems often 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, an 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.
An HVAC system may also provide outdoor air into a structure for ventilation. In some instances, an HVAC system includes a ventilation unit, such as a dedicated outdoor air system, for delivering outdoor air to indoor spaces. The humidity of the outdoor air provided by the HVAC system to the indoor spaces may be controlled to improve indoor air quality and comfort.
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.
Some embodiments of the present disclosure generally relate to HVAC systems that provide outdoor air to indoor spaces for ventilation. More specifically, some embodiments relate to an HVAC system having electronic expansion valves and an associated electronic expansion valve controller that facilitate use of a ventilation unit with an outdoor unit. In some instances, the electronic expansion valves and associated controller enable connection between a ventilation unit made by one manufacturer and a variable refrigerant flow outdoor unit made by a different manufacturer.
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 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
The HVAC system 10 of
The depicted HVAC system 10 also includes a ventilation unit 26 that provides outdoor air to the interior of the structure 12. The ventilation unit 26 includes an air handler and, in at least some instances, may be a dedicated outdoor-air supply (DOAS) air handler unit or an outdoor-air processing unit. As shown in
In certain embodiments, the ventilation unit 26 provides outdoor air mixed with return air from inside the structure (e.g., air passing from an indoor space 14 through return ductwork 32). As an example, the ventilation unit 26 can include a mixing box with one or more louvers that control the amount of indoor air that is mixed with the outdoor air. In other instances, the ventilation unit 26 provides only outdoor air to the indoor spaces 14. The ductwork 28 and 32 can include rigid or flexible ducts.
Fluid refrigerant circulates between the outdoor unit 16 and the ventilation unit 26 through the network 20 of refrigerant lines generally depicted in
As shown in
As also shown in
The branch selector boxes 46, 48, and 50 direct liquid refrigerant or gas refrigerant to connected units for cooling or heating. For instance, in
For cooling an indoor space 14 with an indoor unit 18, liquid refrigerant may flow from the branch selector box 46 to the heat exchanger 54 of the indoor unit 18 to absorb heat from airflow generated by the fan 56 across the heat exchanger 54. For heating, hot gas refrigerant may flow from the branch selector box 46 to a heat exchanger 54 of an indoor unit 18 to add heat to airflow generated by the fan 56 across the heat exchanger 54. In some instances, the indoor units 18 may be operated in different modes simultaneously. That is, one or more of the indoor units 18 may be operated in a cooling mode while at least one of the other indoor units 18 is operated in a heating mode.
The branch selector boxes 48 and 50 of
Refrigerant may be passed through the dehumidifying coil 62 and the reheat coil 64 to condition air flowing through the housing 70. More particularly, the dehumidifying coil 62 can be used as a cooling coil to decrease humidity of the flowing air by lowering its temperature to remove moisture through condensation (i.e., by chilling the air passing the dehumidifying coil 62 to a temperature below the dew point of the incoming air). This dehumidified air then passes across the reheat coil 64, which can be operated to raise the temperature of the flowing air before discharge from the housing 70. The reheat coil 64 can be used to heat the flowing air to various temperatures, but in some embodiments the reheat coil 64 heats the chilled, dehumidified air to a neutral temperature, such as 65-75° F. (18-24° C.) that may be comfortable for occupants of the structure 12.
The ventilation unit 26 may also include additional components. As shown in
In some instances, an HVAC system 10 includes an outdoor unit 16 and a ventilation unit 26 that are made by the same manufacturer. In others, however, the outdoor unit 16 and the ventilation unit 26 are made by different manufacturers. In at least some embodiments of the present technique, the HVAC system 10 includes an electronic expansion valve (EEV) controller 90 that controls operation of electronic expansion valves that control flow of refrigerant into the dehumidifying coil 62 and the reheat coil 64. This allows use of an outdoor unit 16 made by one manufacturer with a ventilation unit 26 made by either the same manufacturer or a different manufacturer. Because the EEV controller 90 and the electronic expansion valves controlling refrigerant into the dehumidifying coil 62 and the reheat coil 64 enable integration of a ventilation unit 26 from one manufacturer into an HVAC system 10 with an outdoor unit 16 from a different manufacturer, these electronic expansion valves and the EEV controller 90 may be considered an expansion valve adapter kit.
The desired operating parameters and component characteristics of the HVAC system 10 may vary based on the purpose and location of the ventilated structure. For instance, an HVAC system in a humid place may benefit from a large dehumidification capacity and use a large dehumidifying coil 62, while an HVAC system in a dry place may be designed with a smaller dehumidification capacity and dehumidifying coil 62. Assorted options may be included in ventilation units, some of which may not be useful or desirable in certain conditions. The EEV controller 90 and associated electronic expansion valves facilitate connection of a wide array of ventilation units 26 from various manufacturers to an outdoor unit 16, allowing selection of a ventilation unit 26 that is more particularly suited to a given set of design conditions and applications.
To facilitate use with a third-party ventilation unit 26 (i.e., a ventilation unit made by a manufacturer that did not make the outdoor unit 16), the HVAC system 10 is shown in
Although refrigerant lines are generically shown in
The valve boxes 82 are mounted to an exterior surface of the housing 70 of the ventilation unit 26 in some embodiments, although the valve boxes 82 can be installed inside the housing 70 (space permitting) or at another location apart from the housing 70. The valve boxes 82 may include mounting features, such as mounting holes or hanger brackets, to facilitate attachment to the housing 70 or to some other surface. In
The EEV controller 90 includes control circuitry connected in communication with the valve boxes 82 to control operation of the electronic expansion valves 84 and flow of refrigerant to the coils 62 and 64. In
The first and second printed circuit boards 92 and 94 may be connected in communication with one another inside the housing 98. The EEV controller 90 can also have a communication adapter 96 (which may also be referred to as a gateway) to facilitate communication between components using different communication protocols. For instance, in one embodiment the EEV controller 90 is connected in communication with an additional controller 100 that uses a first communication protocol, such as MODBUS, that is different from a second communication protocol used by the printed circuit boards 92 and 94, such as a manufacturer's proprietary communication protocol. The communication adapter 96 can be used to translate between the different communication protocols. In one embodiment, for example, the additional controller 100 is a direct digital control (DDC) controller using the MODBUS communication protocol and the circuit boards 92 and 94 of the EEV controller 90 communicate with each other using a manufacturer's proprietary communication protocol. The communication adapter 96 translates data and command signals passing between the additional controller 100 and the circuit boards 92 and 94 to enable communication between these components.
The additional controller 100 can be connected to a building management system 102. In some cases, the building management system 102 communicates with a different protocol than the additional controller 100. Another communication gateway may be used to allow communication between the additional controller 100 and the building management system 102.
Various data or command signals may be communicated between the EEV controller 90 and the additional controller 100. In one embodiment, a technique for controlling humidity of outdoor air discharged from the ventilation unit 26 includes measuring a dew point temperature of the outdoor air downstream of the dehumidifying coil 62 and comparing the measured dew point temperature to a target dew point temperature for the outdoor air downstream of the dehumidifying coil 62. The magnitude of the difference between the measured dew point temperature and the target dew point temperature can then be reduced by sending a control signal from the EEV controller 90 (e.g., from the printed circuit board 92) to the electronic expansion valve 84 connected to the dehumidifying coil 62 to change a rate of refrigerant flow into the dehumidifying coil 62. Measuring the dew point temperature of the outdoor air downstream of the dehumidifying coil 62 may include determining the dew point temperature based on measured temperature and relative humidity downstream of the dehumidifying coil 62, which may be measured with temperature and humidity sensors downstream of the coil 62 (e.g., in the housing 70 of the ventilation unit 26).
In some cases, the additional controller 100 (e.g., a DDC controller) compares the measured dew point temperature to the target dew point temperature to determine a target dew point temperature difference, in which the target dew point temperature difference is the difference between the target dew point temperature and the current dew point temperature downstream from the dehumidifying coil 62. The additional controller 100 communicates the target dew point temperature difference to the EEV controller 90. If this difference indicates that the current heat transfer capability of the dehumidifying coil 62 is insufficient (i.e., the coil 62 is not sufficiently dehumidifying the air), the EEV controller 90 (e.g., the printed circuit board 92) sends a control signal to operate the electronic expansion valve 84 connected to the dehumidifying coil 62 to increase a rate of refrigerant flow into the dehumidifying coil 62 so as to increase the cooling capability of the coil 62 and provide further dehumidification of the air routed through the ventilation unit 26. If the target dew point temperature difference instead indicates that the current heat transfer capability of the dehumidifying coil 62 exceeds that needed to reach the target dew point temperature (i.e., the coil 62 is removing too much moisture from the air), the EEV controller 90 can send a control signal to the electronic expansion valve 84 to decrease the rate of refrigerant flow into the dehumidifying coil 62. In this example, control of the electronic expansion valve 84 by the EEV controller 90 is based on the target dew point temperature difference provided from the additional controller 100; the EEV controller 90 does not need to know the temperature between the dehumidifying coil 62 and the reheat coil 64. Further, in at least some instances, the target dew point temperature difference is calculated using sensors already installed in the ventilation unit 26 (e.g., by the manufacturer) without the addition of extra sensors.
In another embodiment, a technique for controlling a blowout temperature of the ventilation unit 26 (i.e., the temperature of air discharged from the ventilation unit 26) includes both controlling a heat exchanging capacity of the outdoor unit 16 and controlling a heat exchanging capacity of the dehumidifying coil 62. The heat exchanging capacity of the outdoor unit 16 is controlled by changing an evaporation temperature of the refrigerant toward a target evaporation temperature, or by changing a condensation temperature of the refrigerant toward a target condensation temperature, through changing an operating speed of the compressor 36. This may be referred to as evaporation temperature/condensation temperature control. The heat exchanging capacity of the dehumidifying coil 62 is controlled through operation of an electronic expansion valve 84 to change an amount of superheating of the refrigerant by the dehumidifying coil 62 or an amount of supercooling of the refrigerant by the dehumidifying coil 62; the heat exchanging capacity of the reheat coil 64 is controlled through operation of an electronic expansion valve 84 to change an amount of supercooling of the refrigerant by the reheat coil 64. This may be referred to as subcool/superheat control. In at least one embodiment, when reducing a heat exchanging capacity, the HVAC system 10 first tries to perform evaporation temperature/condensation temperature control to reduce the rotational speed of the compressor 36 efficiently. If evaporation temperature/condensation temperature control does not sufficiently reduce the capacity, the HVAC system 10 may change to subcool/superheat control, such as raising the subcool or superheat (e.g., by operating an electronic expansion valve 84 to reduce refrigerant flow through the coil 62) to decrease the heat exchanging capacity of the dehumidifying coil 62.
While a single EEV controller 90 is depicted in
Another embodiment of an HVAC system having multiple EEV controllers 90 is shown in
In some instances, the HVAC system 10 can include decentralized ventilation with multiple ventilation units 26 to provide outdoor air to a structure. By way of example,
Finally, those skilled in the art will appreciate that a processor-based controller can be programmed to facilitate performance of the above-described processes. By way of example, the printed circuit boards 92 and 94 of the EEV controller 90 and the additional controller 100 may include a processor-based controller. One example of such a controller 130 is generally depicted in
An interface 146 of the controller 130 enables communication between the processor 132 and various input devices 148 and output devices 150. The interface 146 can include any suitable device that enables this communication, such as a modem or serial port. In some embodiments in which the controller 130 is part of the EEV controller 90, the additional controller 100, or some other component of the HVAC system 10, the input devices 148 can include sensors, other HVAC components, and user-input devices, and the output devices 150 can include displays, lights, and other HVAC components.
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.
