CONTROL SYSTEM FOR AN HVAC SYSTEM

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Application No. 63/727,607, entitled “A CONTROL SYSTEM FOR AN HVAC SYSTEM,” filed Dec. 3, 2024, which is hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. 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 disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

A heating, ventilation, and air conditioning (HVAC) system may be used to thermally regulate an environment, such as a space within a building, home, or other structure. The HVAC system generally includes a vapor compression system having heat exchangers, such as a condenser and an evaporator, which transfer thermal energy between the HVAC system and the environment. Typically, a compressor is fluidly coupled to a refrigerant circuit of the vapor compression system and is configured to circulate a working fluid (e.g., refrigerant) between the condenser and the evaporator. In this way, the compressor facilitates heat exchange between the refrigerant, the condenser, and the evaporator. In some instances, one or more components of the HVAC system may be controlled to achieve desired or target operating parameter values of the working fluid at various locations along the refrigerant circuit, and the HVAC system may include a control system configured to control operation of the one or more components. Unfortunately, many control systems for HVAC systems are expensive and/or difficult to implement.

SUMMARY

In one embodiment, a heating, ventilation, and air conditioning (HVAC) system includes a working fluid circuit configured to direct a working fluid therethrough, a compressor disposed along the working fluid circuit, a condenser disposed along the working fluid circuit and configured to receive the working fluid from the compressor, a fan configured to direct an air flow across the condenser, a temperature sensor coupled to the condenser, and a controller communicatively coupled to the compressor, the fan, and the temperature sensor. The controller is configured to receive data indicative of a temperature of the working fluid from the temperature sensor, determine a pressure of the working fluid based on the data, and control operation of the compressor, the fan, or both based on the pressure.

In another embodiment, a control system for a heating, ventilation, and air conditioning (HVAC) system includes a temperature sensor coupled to a coil of a condenser of the HVAC system and a controller communicatively coupled to the temperature sensor. The controller is configured to receive, via the temperature sensor, data indicative of a temperature of a working fluid directed through the coil of the condenser, determine a saturated pressure of the working fluid based on the data, and compare the saturated pressure to a threshold value. In response to a determination that the saturated pressure exceeds the threshold value, the controller is configured to adjust a frequency of a compressor of the HVAC system, adjust a speed of a fan configured to force an air flow across the coil of the condenser, or both.

In a further embodiment, a controller of a heating, ventilation, and air conditioning (HVAC) system includes a non-transitory, computer-readable medium having instructions stored thereon. The instructions, when executed by processing circuitry of the controller, are configured to cause the controller to receive, via a temperature sensor coupled to a condenser of the HVAC system, data indicative of a temperature of a working fluid directed through the condenser, determine a saturated pressure of the working fluid based on the data and based on working fluid reference data stored on the non-transitory, computer-readable medium, and compare the saturated pressure to a threshold value. In response to a determination that the saturated pressure exceeds the threshold value, the controller is configured to reduce a frequency of a compressor of the HVAC system, increase a speed of a fan configured to force an air flow across the condenser, or both.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a building incorporating a heating, ventilation, and air conditioning (HVAC) system in a commercial setting, in accordance with an aspect of the present disclosure;

FIG. 2 is a perspective view of an embodiment of a packaged HVAC unit, in accordance with an aspect of the present disclosure;

FIG. 3 is a perspective view of an embodiment of a split HVAC system, in accordance with an aspect of the present disclosure;

FIG. 4 is a schematic diagram of an embodiment of a vapor compression system used in an HVAC system, in accordance with an aspect of the present disclosure;

FIG. 5 is a schematic diagram of an embodiment of an HVAC system including a control system, in accordance with an aspect of the present disclosure; and

FIG. 6 is a schematic of an embodiment of a controller of a control system for an HVAC system, in accordance with an aspect of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. 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 of the present disclosure, the articles “a,” “an,” and “the” 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. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

As used herein, the terms “approximately,” “generally,” and “substantially,” and so forth, are intended to convey that the property value being described may be within a relatively small range of the property value, as those of ordinary skill would understand. For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to) a given value, this is intended to mean that the property value may be within +/−5%, within +/−4%, within +/−3%, within +/−2%, within +/−1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” to another feature, “generally perpendicular” to another feature, and so forth, this is intended to mean that the given feature is within +/−5%, within +/−4%, within +/−3%, within +/−2%, within +/−1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular to another feature, and so forth. Further, it should be understood that mathematical terms, such as “planar,” “slope,” “perpendicular,” “parallel,” and so forth are intended to encompass features of surfaces or elements as understood to one of ordinary skill in the relevant art, and should not be rigidly interpreted as might be understood in the mathematical arts. For example, a “planar” surface is intended to encompass a surface that is machined, molded, or otherwise formed to be substantially flat or smooth (within related tolerances) using techniques and tools available to one of ordinary skill in the art. Similarly, a surface having a “slope” is intended to encompass a surface that is machined, molded, or otherwise formed to be oriented at an angle (e.g., incline) with respect to a point of reference using techniques and tools available to one of ordinary skill in the art.

As briefly discussed above, a heating, ventilation, and air conditioning (HVAC) system may be used to thermally regulate a space or other load within a building, home, or other suitable structure. For example, the HVAC system may include a vapor compression system that transfers thermal energy between a working fluid, such as a refrigerant, and a fluid to be conditioned, such as air or water. The vapor compression system includes heat exchangers, such as a condenser and an evaporator, which are fluidly coupled to one another via one or more conduits of a working fluid loop or circuit (e.g., refrigerant circuit). A compressor may be implemented to circulate the working fluid through the conduits and other components of the working fluid circuit (e.g., an expansion device) and, thus, enable the transfer of thermal energy between components of the working fluid circuit (e.g., between the condenser and the evaporator) and one or more thermal loads (e.g., an environmental air flow, a supply air flow, a supply water flow). The HVAC system may be configured to operate in a cooling mode to enable cooling of a thermal load. In some embodiments, the HVAC system may also be configured to operate in a heating mode to provide heating to the thermal load.

In many HVAC systems, the working fluid directed along the working fluid circuit may be a two-phase working fluid (e.g., two-phase refrigerant). The working fluid may therefore undergo one or more phase changes (e.g., between a liquid phase and a gas phase) as the working fluid is circulated through the HVAC system. For example, the working fluid may transition from one phase to another during pressurization of the working fluid (e.g., via the compressor), during expansion of the working fluid (e.g., via an expansion device), in response to transfer of heat to and/or from the working fluid, or any combination thereof. As will be appreciated, one or more components of the working fluid circuit may be configured or designed to operate with the working fluid having certain characteristics, properties, attributes, and/or operating parameter values. For example, some compressors may be designed to operate with the working fluid in a gaseous phase (e.g., vapor phase). Introduction of working fluid in a liquid phase to the compressor may cause wear and/or degradation to the compressor. Additionally or alternatively, one or more components of the working fluid circuit may be configured to operate more efficiently with the working fluid having certain characteristics, properties, attributes, and/or operating parameter values. For example, an expansion device of the working fluid circuit may operate more efficiently when the expansion device receives the working fluid in a liquid phase instead of a gaseous phase. Accordingly, HVAC systems may include a control system configured to operate the working fluid circuit to achieve one or more desired characteristics, properties, attributes, and/or operating parameter values of the working fluid at different locations along the working fluid circuit.

To enable operational control of the components of the working fluid circuit, control systems in HVAC systems may be configured to receive data and/or feedback from one or more sensors and/or other components of the HVAC system. Unfortunately, many components incorporated with HVAC systems to enable control of HVAC system components are expensive and/or difficult to implement. For example, some HVAC control systems include a high pressure sensor configured to detect a pressure (e.g., discharge pressure) of the working fluid discharged by the compressor. Unfortunately, high pressure sensors are costly and/or may not be suitable for implementation in some HVAC system.

Accordingly, embodiments of the present disclosure are directed to an HVAC system having a control system configured to operate one or more components of the HVAC system utilizing data and/or feedback from one or more devices that are more cost-effective and/or that may be implemented in HVAC systems with reduced complications. For example, the control system may include a controller and a temperature sensor communicatively coupled to the controller. The temperature sensor may be implemented with a condenser and/or outdoor heat exchanger of the HVAC system. In particular, the temperature sensor may be coupled to (e.g., directly coupled to, attached to) a tube of the condenser. The controller may receive data indicative of a temperature of the condenser and/or working fluid within the condenser (e.g., saturated working fluid temperature) and may adjust operation of one or more components of the HVAC system (e.g., compressor, condenser fan) based on the data (e.g., temperature data). In some implementations, the controller may be configured to manipulate the temperature data to calculate or otherwise determine a pressure (e.g., saturated pressure, condensing pressure, discharge pressure) of the working fluid and then adjust operation of the one or more components of the HVAC system based on the calculated pressure. Additionally or alternatively, the controller may be configured to adjust operation of the one or more components of the HVAC system based on the temperature data and without calculating a pressure of the working fluid. In any case, the disclosed techniques enable desired operational control of the HVAC system without use of costly high-pressure sensors typically included in many HVAC systems.

Turning now to the drawings, FIG. 1 illustrates an embodiment of a heating, ventilation, and air conditioning (HVAC) system for environmental management that employs one or more HVAC units in accordance with the present disclosure. As used herein, an HVAC system includes any number of components configured to enable regulation of parameters related to climate characteristics, such as temperature, humidity, air flow, pressure, air quality, and so forth. For example, an “HVAC system” as used herein is defined as conventionally understood and as further described herein. Components or parts of an “HVAC system” may include, but are not limited to, all, some of, or individual parts such as a heat exchanger, a heater, an air flow control device, such as a fan, a sensor configured to detect a climate characteristic or operating parameter, a filter, a control device configured to regulate operation of an HVAC system component, a component configured to enable regulation of climate characteristics, or a combination thereof. An “HVAC system” is a system configured to provide such functions as heating, cooling, ventilation, dehumidification, pressurization, refrigeration, filtration, or any combination thereof. The embodiments described herein may be utilized in a variety of applications to control climate characteristics, such as residential, commercial, industrial, transportation, or other applications where climate control is desired.

In the illustrated embodiment, a building 10 is air conditioned by a system that includes an HVAC unit 12 in accordance with present embodiments. The building 10 may be a commercial structure, a residential structure, or other suitable structure. As shown, the HVAC unit 12 is disposed on the roof of the building 10; however, the HVAC unit 12 may be located in other equipment rooms or areas adjacent the building 10. The HVAC unit 12 may be a single package unit containing other equipment, such as a blower, integrated air handler, and/or auxiliary heating unit. In other embodiments, the HVAC unit 12 may be part of a split HVAC system, such as the system shown in FIG. 3, which includes an outdoor HVAC unit 58 and an indoor HVAC unit 56.

The HVAC unit 12 is an air-cooled system that implements a refrigeration cycle to provide conditioned air to the building 10. Specifically, the HVAC unit 12 may include one or more heat exchangers across which an air flow is passed to condition the air flow before the air flow is supplied to the building. In the illustrated embodiment, the HVAC unit 12 is a rooftop unit (RTU) that conditions a supply air stream, such as environmental air and/or a return air flow from the building 10. After the HVAC unit 12 conditions the air, the air is supplied to the building 10 via ductwork 14 extending throughout the building 10 from the HVAC unit 12. For example, the ductwork 14 may extend to various individual floors or other sections of the building 10. In certain embodiments, the HVAC unit 12 may be a heat pump that provides both heating and cooling to the building with one working fluid circuit configured to operate in different modes. In other embodiments, the HVAC unit 12 may include one or more working fluid circuits for cooling an air stream and a furnace for heating the air stream.

A control device 16, one type of which may be a thermostat, may be used to designate the temperature of the conditioned air. The control device 16 also may be used to control the flow of air through the ductwork 14. For example, the control device 16 may be used to regulate operation of one or more components of the HVAC unit 12 or other components, such as dampers and fans, within the building 10 that may control flow of air through and/or from the ductwork 14. In some embodiments, other devices may be included in the system, such as pressure and/or temperature transducers or switches that sense the temperatures and pressures of the supply air, return air, and so forth. Moreover, the control device 16 may include computer systems that are integrated with or separate from other building control or monitoring systems, and even systems that are remote from the building 10.

FIG. 2 is a perspective view of an embodiment of the HVAC unit 12. In the illustrated embodiment, the HVAC unit 12 is a single package unit that may include one or more independent working fluid circuits and components that are tested, charged, wired, piped, and ready for installation. The HVAC unit 12 may provide a variety of heating and/or cooling functions, such as cooling only, heating only, cooling with electric heat, cooling with dehumidification, cooling with gas heat, or cooling with a heat pump. As described above, the HVAC unit 12 may directly cool and/or heat an air stream provided to the building 10 to condition a space in the building 10.

As shown in the illustrated embodiment of FIG. 2, a cabinet 24 encloses the HVAC unit 12 and provides structural support and protection to the internal components from environmental and other contaminants. In some embodiments, the cabinet 24 may be constructed of galvanized steel and insulated with aluminum foil faced insulation. Rails 26 may be joined to the bottom perimeter of the cabinet 24 and provide a foundation for the HVAC unit 12. In certain embodiments, the rails 26 may provide access for a forklift and/or overhead rigging to facilitate installation and/or removal of the HVAC unit 12. In some embodiments, the rails 26 may fit into “curbs” on the roof to enable the HVAC unit 12 to provide air to the ductwork 14 from the bottom of the HVAC unit 12 while blocking elements such as rain from leaking into the building 10.

The HVAC unit 12 includes heat exchangers 28 and 30 in fluid communication with one or more working fluid circuits. Tubes within the heat exchangers 28 and 30 may circulate working fluid, such as R-410A, through the heat exchangers 28 and 30. The tubes may be of various types, such as multichannel tubes, conventional copper or aluminum tubing, and so forth. Together, the heat exchangers 28 and 30 may implement a thermal cycle in which the working fluid undergoes phase changes and/or temperature changes as it flows through the heat exchangers 28 and 30 to produce heated and/or cooled air. For example, the heat exchanger 28 may function as a condenser where heat is released from the working fluid to ambient air, and the heat exchanger 30 may function as an evaporator where the working fluid absorbs heat to cool an air stream. In other embodiments, the HVAC unit 12 may operate in a heat pump mode where the roles of the heat exchangers 28 and 30 may be reversed. That is, the heat exchanger 28 may function as an evaporator and the heat exchanger 30 may function as a condenser. In further embodiments, the HVAC unit 12 may include a furnace for heating the air stream that is supplied to the building 10. While the illustrated embodiment of FIG. 2 shows the HVAC unit 12 having two of the heat exchangers 28 and 30, in other embodiments, the HVAC unit 12 may include one heat exchanger or more than two heat exchangers.

The heat exchanger 30 is located within a compartment 31 that separates the heat exchanger 30 from the heat exchanger 28. Fans 32 draw air from the environment through the heat exchanger 28. Air may be heated and/or cooled as the air flows through the heat exchanger 28 before being released back to the environment surrounding the HVAC unit 12. A blower assembly 34, powered by a motor 36, draws air through the heat exchanger 30 to heat or cool the air. The heated or cooled air may be directed to the building 10 by the ductwork 14, which may be connected to the HVAC unit 12. Before flowing through the heat exchanger 30, the conditioned air flows through one or more filters 38 that may remove particulates and contaminants from the air. In certain embodiments, the filters 38 may be disposed on the air intake side of the heat exchanger 30 to prevent contaminants from contacting the heat exchanger 30.

The HVAC unit 12 also may include other equipment for implementing the thermal cycle. Compressors 42 increase the pressure and temperature of the working fluid (e.g., refrigerant) before the working fluid enters the heat exchanger 28. The compressors 42 may be any suitable type of compressors, such as scroll compressors, rotary compressors, screw compressors, or reciprocating compressors. In some embodiments, the compressors 42 may include a pair of hermetic direct drive compressors arranged in a dual stage configuration 44. However, in other embodiments, any number of the compressors 42 may be provided to achieve various stages of heating and/or cooling. As may be appreciated, additional equipment and devices may be included in the HVAC unit 12, such as a solid-core filter drier, a drain pan, a disconnect switch, an economizer, pressure switches, phase monitors, and humidity sensors, among other things.

The HVAC unit 12 may receive power through a terminal block 46. For example, a high voltage power source may be connected to the terminal block 46 to power the equipment. The operation of the HVAC unit 12 may be governed or regulated by a control board 48. The control board 48 may include control circuitry connected to a thermostat, sensors, and alarms. One or more of these components may be referred to herein separately or collectively as the control device 16. The control circuitry may be configured to control operation of the equipment, provide alarms, and monitor safety switches. Wiring 49 may connect the control board 48 and the terminal block 46 to the equipment of the HVAC unit 12.

FIG. 3 illustrates a split heating and cooling system 50 (e.g., split HVAC system), also in accordance with present techniques. The split heating and cooling system 50 may provide heated and cooled air to a structure, such as a home or residence, as well as provide outside air for ventilation and provide improved indoor air quality (IAQ) through devices such as ultraviolet lights and air filters. In general, a structure 52 (e.g., thermal load) conditioned by the split heating and cooling system 50 may include working fluid conduits 54 (e.g., refrigerant conduits) that operatively couple the indoor unit 56 to the outdoor unit 58. The indoor unit 56 may be positioned in a utility room, an attic, a basement, and so forth. The outdoor unit 58 is typically situated adjacent to a side of the structure 52 and is covered by a shroud to protect the system components and to prevent leaves and other debris or contaminants from entering the outdoor unit 58. The working fluid conduits 54 transfer working fluid between the indoor unit 56 and the outdoor unit 58, typically transferring primarily liquid working fluid in one direction and primarily vaporized working fluid in an opposite direction.

When the split heating and cooling system 50 operates as an air conditioner, a heat exchanger 60 in the outdoor unit 58 serves as a condenser for re-condensing vaporized working fluid flowing from the indoor unit 56 to the outdoor unit 58 via one of the working fluid conduits 54. During such operation, a heat exchanger 62 of the indoor unit functions as an evaporator. Specifically, the heat exchanger 62 receives liquid working fluid, which may be expanded by an expansion device, and evaporates the working fluid before returning it to the outdoor unit 58.

The outdoor unit 58 draws environmental air through the heat exchanger 60 using a fan 64 and expels the air above the outdoor unit 58. When operating as an air conditioner, the air is heated by the heat exchanger 60 within the outdoor unit 58 and exits the unit at a temperature higher than it entered. The indoor unit 56 includes a blower or fan 66 that directs air through or across the indoor heat exchanger 62, where the air is cooled when the system is operating in the air conditioning (e.g., cooling) mode. Thereafter, the air is passed through ductwork 68 that directs the air to the structure 52. The overall system operates to maintain a desired temperature as set by a system controller. When the temperature sensed inside the structure 52 is higher than the set point on the thermostat, or the set point plus a small amount, the split heating and cooling system 50 may become operative to refrigerate additional air for circulation through the structure 52. When the temperature reaches the set point, or the set point minus a small amount, the split heating and cooling system 50 may stop the refrigeration cycle temporarily.

The split heating and cooling system 50 may be configured as a heat pump. When operating as a heat pump in a heating mode, the roles of heat exchangers 60 and 62 are reversed. That is, the heat exchanger 60 of the outdoor unit 58 will serve as an evaporator to evaporate working fluid and thereby cool air entering the outdoor unit 58 as the air passes over the outdoor heat exchanger 60. The indoor heat exchanger 62 will receive a stream of air blown over it and will heat the air by condensing the working fluid.

In some embodiments, the indoor unit 56 may include a furnace system 70. For example, the indoor unit 56 may include the furnace system 70 when the split heating and cooling system 50 is not configured to operate as a heat pump. For example, the furnace system 70 may include an electric heating coil, separate from heat exchanger 62, such that air directed by the blower 66 passes over the electric heating coil and extracts heat from the electric heating coil. The heated air may then be routed from the furnace system 70 to the ductwork 68 for heating the structure 52.

FIG. 4 is an embodiment of a vapor compression system 72 that can be used in any of the systems described above. The vapor compression system 72 may circulate a working fluid (e.g., refrigerant) through a circuit starting with a compressor 74. The circuit may also include a condenser 76, an expansion valve(s) or device(s) 78, and an evaporator 80. The vapor compression system 72 may further include a control panel 82 that has an analog to digital (A/D) converter 84, a microprocessor 86, a non-volatile memory 88, and/or an interface board 90. The control panel 82 and its components may function to regulate operation of the vapor compression system 72 based on feedback from an operator, from sensors of the vapor compression system 72 that detect operating conditions, and so forth.

In some embodiments, the vapor compression system 72 may use one or more of a variable speed drive (VSDs) 92, a motor 94, the compressor 74, the condenser 76, the expansion valve or device 78, and/or the evaporator 80. The motor 94 may drive the compressor 74 and may be powered by the variable speed drive (VSD) 92. The VSD 92 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 94. In other embodiments, the motor 94 may be powered directly from an AC or direct current (DC) power source. The motor 94 may include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

The compressor 74 compresses a working fluid vapor and delivers the vapor to the condenser 76 through a discharge passage. In some embodiments, the compressor 74 may be a centrifugal compressor. The working fluid vapor delivered by the compressor 74 to the condenser 76 may transfer heat to a fluid passing across the condenser 76, such as ambient or environmental air 96. The working fluid vapor may condense to a working fluid liquid in the condenser 76 as a result of thermal heat transfer with the environmental air 96. The liquid working fluid from the condenser 76 may flow through the expansion device 78 to the evaporator 80.

The liquid working fluid delivered to the evaporator 80 may absorb heat from another air stream, such as a supply air stream 98 provided to the building 10 or the structure 52. For example, the supply air stream 98 may include ambient or environmental air, return air from a building, or a combination of the two. The liquid working fluid in the evaporator 80 may undergo a phase change from the liquid working fluid to a working fluid vapor. In this manner, the evaporator 80 may reduce the temperature of the supply air stream 98 via thermal heat transfer with the working fluid. Thereafter, the vapor working fluid exits the evaporator 80 and returns to the compressor 74 by a suction line to complete the cycle. In accordance with the present techniques, the condenser 76 of the vapor compression system 72 may include a temperature sensor 99 (e.g., thermocouple) configured to detect a temperature of a component of the condenser 76 and/or a temperature the working fluid within the condenser 76. The temperature sensor 99 may provide data indicative of the temperature to a control system (e.g., control board 82), which may be configured to regulate operation of one or more components of the vapor compression system 72 based on the data. Details of the present techniques are described further below.

It should be appreciated that any of the features described herein may be incorporated with the HVAC unit 12, the split heating and cooling system 50, or other HVAC systems. Additionally, while the features disclosed herein are described in the context of embodiments that heat and cool a supply air stream provided to a building or other load, embodiments of the present disclosure may be incorporated with other HVAC systems as well. For example, the features described herein may be applied to mechanical cooling systems, free cooling systems, chiller systems, and/or other heat pump or refrigeration applications.

As briefly discussed above, embodiments of the present disclosure are directed to an HVAC system having a control system configured to operate one or more components of the HVAC system utilizing data and/or feedback from one or more devices that are more cost-effective and/or that may be implemented in HVAC systems with reduced complications. For example, the control system may include a controller and a temperature sensor communicatively coupled to the controller. The temperature sensor may be implemented with a condenser and/or outdoor heat exchanger of the HVAC system, and the controller may receive data indicative of a temperature of the condenser and/or working fluid within the condenser (e.g., saturated working fluid temperature) and may adjust operation of one or more components of the HVAC system (e.g., compressor, condenser fan) based on the data (e.g., temperature data). As will be appreciated, the disclosed techniques enable desired operational control of the HVAC system without use of costly high-pressure sensors typically included in many HVAC systems but may nevertheless enable desired operation of the HVAC system and, for example, mitigate operation of the HVAC system with the working fluid exceeding one or more threshold pressure levels.

To provide context for the following discussion, FIG. 5 is a schematic of an embodiment of an HVAC system 100 in accordance with present embodiments. The HVAC system 100 may include one or more components of the vapor compression system 72 discussed above and/or may be included in any of the systems described above (e.g., HVAC unit 12, split heating and cooling system 50). The HVAC system 100 includes a working fluid circuit 102 (e.g., one or more conduits, refrigerant circuit) having a first heat exchanger 104 and a second heat exchanger 106 that are fluidly coupled to one another via the working fluid circuit 102. The first heat exchanger 104 may be in thermal communication with (e.g., fluidly coupled to) a thermal load 108 (e.g., a room, space, and/or device) serviced by the HVAC system 100, and the second heat exchanger 106 may be in thermal communication with an ambient environment 110 (e.g., atmosphere, outdoor environment) surrounding the HVAC system 100.

In some embodiments, a first fan 114 (e.g., blower) may direct a first air flow 116 across the first heat exchanger 104 to facilitate heat exchange between working fluid within the first heat exchanger 104 and the thermal load 108. The HVAC system 100 may also include a second fan 118 configured to direct a second air flow 120 across the second heat exchanger 106 to facilitate heat exchange between working fluid within the second heat exchanger 106 and the ambient environment 110. In some embodiments, the first heat exchanger 104 may include one or more tubes 122 (e.g., a plurality of tubes, at least one tube, circuit, rows, first tubes, conduits, one or more coils, one or more passes, evaporator coil) configured to direct working fluid through the first heat exchanger 104. The first fan 114 may induce flow of the first air flow 116 across the tubes 122, and the first heat exchanger 104 may thereby place the first air flow 116 in a heat exchange relationship with the working fluid flowing through the tubes 122. In some embodiments, the first heat exchanger 104 may be configured to operate as an evaporator (e.g., in a cooling mode of the HVAC system 100), and the first heat exchanger 104 may therefore enable transfer of heat from the first air flow 116 to the working fluid to cool the first air flow 116 and vaporize the working fluid within the first heat exchanger 104. It should be appreciated that the first heat exchanger 104 may include additional and/or alternative components (e.g., fins, shell, plates, etc.), configurations (e.g., slab), operating modes, and so forth.

As shown in the illustrated embodiment, the second heat exchanger 106 also includes include one or more tubes 124 (e.g., a plurality of tubes, at least one tube, circuit, rows, second tubes, conduits, one or more coils, one or more passes, condenser coil) configured to direct working fluid through the second heat exchanger 106. The second fan 118 may induce flow of the second air flow 120 across the tubes 124, and the second heat exchanger 106 may thereby place the second air flow 120 in a heat exchange relationship with the working fluid flowing through the tubes 124. In accordance with the present techniques, the second heat exchanger 106 may be configured to operate as a condenser (e.g., in a cooling mode of the HVAC system 100), and the second heat exchanger 106 may enable transfer of heat from the working fluid to the second air flow 120 to the working fluid to heat the second air flow 120 and condense the working fluid within the second heat exchanger 106. It should be appreciated that the second heat exchanger 106 may include additional and/or alternative components (e.g., fins, shell, plates, etc.), configurations (e.g., slab), operating modes, and so forth.

In the illustrated embodiment, the HVAC system 100 (e.g., working fluid circuit 102) also includes an expansion device 126 (e.g., throttling device, electronic expansion valve [EEV]) disposed along the working fluid circuit 102. The expansion device 126 is positioned between the first heat exchanger 104 and the second heat exchanger 106 and is configured to regulate (e.g., throttle) a flow of working fluid and/or a working fluid pressure differential between the first heat exchanger 104 and the second heat exchanger 106.

The HVAC system 100 (e.g., working fluid circuit 102) further includes a compressor 128 disposed along the working fluid circuit 102. The compressor 128 is configured to direct working fluid flow along the working fluid circuit 102. Specifically, the compressor 128 is configured (e.g., in a cooling mode of the HVAC system 100) to direct the working fluid to the second heat exchanger 106 (e.g., outdoor heat exchanger, condenser). From the second heat exchanger 106, the working fluid circuit 102 may direct the working fluid through the expansion device 126, the first heat exchanger 104, and back to the compressor 128. To this end, the working fluid circuit 102 includes a discharge conduit 130 extending from the compressor 128 (e.g., an outlet 132 or discharge port of the compressor 128) to the second heat exchanger 106. The working fluid circuit 102 also includes a liquid conduit 134 extending between first heat exchanger 104 and the second heat exchanger 106, with the expansion device 126 disposed along the liquid conduit 134. The working fluid circuit 102 also includes a suction conduit 136 (e.g., one or more conduits) that extends from the first heat exchanger 104 to the compressor 128 (e.g., an inlet 138 or suction port of the compressor 128). Therefore, the compressor 128 may operate to draw (e.g., intake) the working fluid (e.g., low pressure working fluid) from the first heat exchanger 104 (e.g., via the suction conduit 136), compress the working fluid, and discharge (e.g., output) the working fluid (e.g., high pressure working fluid) to the second heat exchanger 106 (e.g., via the discharge conduit 130).

As mentioned above, one or more components of the working fluid circuit 102 may be configured or designed to operate with the working fluid having certain characteristics, properties, attributes, and/or operating parameter values. For example, some embodiments of the compressor 128 may be designed to operate with the working fluid in a gaseous phase (e.g., vapor phase). In certain embodiments, introduction of working fluid in a liquid phase to the compressor 128 may cause wear and/or degradation to the compressor. As another example, the expansion device 126 may be configured to designed to operate more efficiently and/or effectively when the working fluid received by the expansion device 126 (e.g., via the liquid conduit 134) is in a liquid phase. As a further example, it may be desirable to maintain a pressure (e.g., discharge pressure, saturation pressure) of the working fluid discharged by the compressor 128 at or below one or more threshold levels (e.g., threshold pressure levels). Such operations may be desirable to protect one or more components of the HVAC system 100 (e.g., compressor 128, working fluid circuit 102) from unintended wear and/or degradation, mitigate instances of unscheduled maintenance and/or operational downtime, and so forth.

Accordingly, the HVAC system 100 includes a control system 140 configured to regulate operation of one or more components of the HVAC system 100. In particular, the control system 140 may be configured to enable operational adjustments to one or more components of the HVAC system 100 in order to maintain and/or achieve desired characteristics, properties, attributes, and/or operating parameter values of the working fluid along one or more portions of the working fluid circuit 102 (e.g., discharge conduit 130). Many existing HVAC systems include a high-pressure sensor (e.g., high-pressure switch), which may be disposed downstream of a compressor and along a discharge conduit, in order detect and monitor a pressure of working fluid discharged by the compressor and avoid excessive pressures of the working fluid. Unfortunately, high-pressure sensors are expensive and may be unsuitable for incorporation into certain HVAC systems. Embodiments of the HVAC system 100 disclosed herein do not include a high-pressure sensor (e.g., disposed along the discharge conduit 130) and are nevertheless configured to enable operational control of the HVAC system 100 to maintain and/or achieve desired characteristics, properties, attributes, and/or operating parameter values of the working fluid along one or more portions of the working fluid circuit 102 (e.g., avoid excessive pressures of the working fluid along the discharge conduit 130) and implement corresponding control actions to these ends. Present embodiments therefore enable such benefits for a wider range of configurations of the HVAC system 100 and at substantially reduced costs (e.g., production costs, maintenance costs, operating costs).

The control system 140 may include a controller 142 (e.g., control panel, control circuitry, automation controller) that is communicatively coupled to one or more components of the HVAC system 100 and is configured to monitor, adjust, and/or otherwise control operation of the components of the HVAC system 100. For example, one or more control transfer devices, such as wires, cables, wireless communication devices, and the like, may communicatively couple the compressor 128, the expansion device 126, the first and/or second fans 114, 118, the control device 16 (e.g., thermostat), and/or any other suitable components of the HVAC system 100 to the controller 142. The compressor 128, the expansion device 126, the first and/or second fans 114, 118, the control device 16 (e.g., thermostat), respective components thereof, and/or any other suitable components of the HVAC system 100 may each have one or more communication components that facilitate wired or wireless (e.g., via a network) communication with the controller 142. In some embodiments, the communication components may include a network interface that enables the components of the HVAC system 100 to communicate via various protocols such as EtherNet/IP, ControlNet, DeviceNet, or any other communication network protocol. Alternatively, the communication components may enable the components of the HVAC system 100 to communicate via mobile telecommunications technology, Bluetooth®, near-field communications technology, and the like. As such, compressor 128, the expansion device 126, the first and/or second fans 114, 118, the control device 16 (e.g., thermostat), respective components thereof, and/or any other suitable components of the HVAC system 100 may wirelessly communicate data between each other. In other embodiments, operational control of certain components of the HVAC system 100 may be regulated by one or more relays or switches (e.g., a 24 volt alternating current [VAC] relay).

In some embodiments, the controller 142 may be a component of or may include the control panel 82. In other embodiments, the controller 142 may be a standalone controller, a dedicated controller, or another suitable controller included in the HVAC system 100. In any case, the controller 142 is configured to control components of the HVAC system 100 in accordance with the techniques discussed herein. The controller 142 includes processing circuitry 144, such as a microprocessor, which may execute software for controlling the components of the HVAC system 100. The processing circuitry 144 may include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICS), or some combination thereof. For example, the processing circuitry 144 may include one or more reduced instruction set (RISC) processors.

The controller 142 may also include a memory device 146 (e.g., a memory) that may store information, such as instructions, control software, lookup tables, configuration data, etc. The memory device 146 may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as read-only memory (ROM). The memory device 146 may store a variety of information and may be used for various purposes. For example, the memory device 146 may store processor-executable instructions including firmware or software for the processing circuitry 144 execute, such as instructions for controlling components of the HVAC system 100. In some embodiments, the memory device 146 is a tangible, non-transitory, machine-readable-medium that may store machine-readable instructions for the processing circuitry 144 to execute. The memory device 146 may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The memory device 146 may store data, instructions, and any other suitable data. The memory device 146 (e.g., memory, memory unit, storage device, etc.) may include one or more devices (e.g., RAM, ROM, flash memory, hard disk storage, etc.) storing data and/or computer code for completing or facilitating one or more of the various processes, layers, and modules described herein. The memory device 146 may include database components, object code components, script components, any other type of information structure, or a combination thereof configured to support the various activities and information structures described herein. Indeed, it should be appreciated that the memory device 146 may include executable instructions for performing any of the techniques disclosed herein.

The control system 140 also includes a temperature sensor 148 (e.g., sensor, thermocouple, temperature sensor 99) communicatively coupled to the controller 142. More specifically, the temperature sensor 148 is implemented (e.g., integrated) with the second heat exchanger 106 (e.g., condenser). The temperature sensor 148 may therefore be coupled to the second heat exchanger 106. As shown, the temperature sensor 148 may be attached to (e.g., directly coupled to, in direct contact with, mounted to) one of the tubes 124 of the second heat exchanger 106. Accordingly, the temperature sensor 148 is implemented to detect, measure, collect, and/or capture data indicative of a temperature of the working fluid directed through the second heat exchanger 106 (e.g., tube 124, condenser coil). For example, the temperature sensor 148 may detect a temperature of a surface of the tube 124. Additionally or alternatively, the temperature sensor 148 may extend at least partially into the tube 124 and may directly detect a temperature of the working fluid therein. In some embodiments, the control system 140 may include multiple temperature sensors 148 implemented with the second heat exchanger 106. For example, multiple temperature sensors 148 may be coupled to (e.g., directly coupled to) one of the tubes 124, different tubes 124 of the second heat exchanger 106, or a combination of both.

The controller 142 is configured to receive data from the temperature sensor 148. In particular, the controller 142 is configured to receive the data indicative of the temperature of the working fluid directed through the second heat exchanger 106 (e.g., saturated temperature) from the temperature sensor 148. The controller 142 may utilize the data to evaluate one or more operational parameters, qualities, characteristics, and/or statuses of the HVAC system 100 and, if desired, implement a corresponding control action in the HVAC system 100. In some embodiments, the controller 142 may be configured to implement one or more control actions (e.g., operational adjustments) in the HVAC system 100 based directly on the data indicative of the temperature of the working fluid directed through the second heat exchanger 106. As discussed in further detail below, the controller 142 may be configured to determine (e.g., calculate, estimate, derive, automatically determine) another operating parameter value or characteristic of the HVAC system 100 (e.g., working fluid) based on the data. For example, the controller 142 may be configured to determine a pressure (e.g., pressure value, determined pressure, calculated pressure) of the working fluid (e.g., saturated pressure, discharge pressure, condensing pressure) based on the data received from the temperature sensor 148. The controller 142 may be further configured to implement one or more control actions (e.g., operational adjustments) in the HVAC system 100 based on the pressure determined via the data received from the temperature sensor 148. Indeed, the present techniques enable such operations without reliance on data from an expensive high-pressure sensor implemented with the HVAC system 100.

In response to a determination that the pressure of the working fluid (e.g., calculated and/or otherwise determined via the data from the temperature sensor 148, pressure within the second heat exchanger 106, pressure along the discharge conduit 130) is above one or more threshold levels (e.g., threshold pressure values), the controller 142 may implement one or more control actions to adjust operation of one or more components of the HVAC system 100. It should be appreciated that the such a determination may be made based on a comparison of the pressure of the working fluid to the one or more threshold values (e.g., via the controller 142). For example, to reduce the pressure of the working fluid, the controller 142 may be configured to adjust operation of the compressor 128. Specifically, the controller 142 may be configured to reduce a frequency (e.g., rotational speed) of the compressor 128 and/or suspend operation of the compressor 128. In the illustrated embodiment, the compressor 128 includes a motor 150 and a VSD 152, either or both of which may be communicatively coupled to the controller 142. In some embodiments, the controller 142 may be configured to adjust operation (e.g., reduce a frequency, reduce a speed, reduce a stage, suspend operation) of the compressor 128 via control of the motor 150, the VSD 152, or both. To this end, the controller 142 may be configured to output one or more control signals to the motor 150, the VSD 152, or both. For example, to reduce the pressure (e.g., determined pressure, saturated pressure, calculated pressure, exhaust pressure) of the working fluid, such that the pressure falls one below one or more threshold values, the controller 142 may be configured to decrease the frequency of the compressor 128 (e.g., via control of the motor 150 and/or the VSD 152) to cause reduced pressurization of the working fluid via the compressor 128.

Additionally or alternatively, the controller 142 may be configured to adjust operation of the second fan 118 (e.g., condenser fan, one or more fans), such as in response to a determination that the pressure of the working fluid (e.g., calculated and/or otherwise determined via the data from the temperature sensor 148, pressure within the second heat exchanger 106, pressure along the discharge conduit 130) is above one or more threshold levels (e.g., threshold pressure values). The controller 142 may be communicatively coupled to a fan motor 154 of the second fan 118, and the fan motor 154 may be configured to drive operation (e.g., rotation) of the second fan 118 to force the second air flow 120 across the second heat exchanger 106. The controller 142 may be configured to output control signals to the fan motor 154 to adjust a speed (e.g., operating speed, rotational speed) of the second fan 118 and thereby adjust a flow rate (e.g., mass flow rate, amount) of the second air flow 120 directed across the second heat exchanger 106 (e.g., tubes 124) and adjust an amount of heat transfer between the second air flow 120 and the working fluid within the second heat exchanger 106. For example, to reduce the pressure (e.g., determined pressure, saturated pressure, calculated pressure) of the working fluid, such that the pressure falls one below one or more threshold values, the controller 142 may be configured to increase a speed of the second fan 118 (e.g., via control of the fan motor 154) to cause an increase in heat transfer between the second air flow 120 and the working fluid within the second heat exchanger 106 and a reduction in the temperature and/or pressure of the working fluid. It should be noted that the controller 142 may be communicatively coupled to the temperature sensor 148, the motor 150, the VSD 152, and/or the fan motor 154 via wireless connections, wired connections, and/or any combination of communicative coupling techniques described herein. Additional details of the control schemes that may be implemented via the control system 140 are described below.

To facilitate the following discussion, FIG. 6 is a schematic of a portion of an embodiment of the HVAC system 100, including the control system 140. For example, the illustrated embodiment includes an embodiment of the controller 142 having additional features that may be implemented in the control system 140 to enable one or more of the functionalities described herein. Although such features are illustrated as elements of the controller 142, it should be appreciated that one or more of the elements and/or features described below may be implemented as an element of another controller and/or may be physically arranged in different configurations (e.g., as respective elements of different controllers and/or control systems). For example, one or more of the elements may be incorporated with the control system 140 of the HVAC system 100 (e.g., control board 82), and one or more elements may be implemented with a building management system configured to control and/or regulate overall operation of the HVAC system 100 in which the control system 140 is implemented.

As described above, the controller 142 may be communicatively coupled to the temperature sensor 148, the compressor 128 (e.g., motor 150, VSD 152), and the second fan 118 (e.g., fan motor 154). In some embodiments, the temperature sensor 148 (e.g., one or more temperature sensors) may periodically establish communication with the controller 142, such as in accordance with a defined or predetermined interval (e.g., once every few seconds, once every few minutes, once every few hours) to transmit data detected by the temperature sensor 148 (e.g., data indicative of a temperature of the working fluid, a temperature of the tube 124). The temperature sensor 148 may be configured to communicate with the controller 142 at different times separated by a predetermined time difference and/or interval. In this way, the controller 142 may more accurately assess and/or evaluate the data received from the temperature sensor 148 and/or parameters derived from the data. The predetermined time difference and/or interval may be defined by an operator and/or user of the HVAC system 100. In some embodiments, the controller 142 may periodically send signals to temperature sensor 148 to request transmission of sensed data from the temperature sensor 148 to the controller 142.

As similarly discussed above, the controller 142 of the illustrated embodiment includes embodiments of the processing circuitry 144 and the memory device 146. The memory device 146 also includes elements and/or features to enable one or more of the functionalities described herein. However, it should be appreciated that one or more elements described below may be implemented with the control system 140 (e.g., controller 142) separately from the memory device 146. As shown, the memory device 146 includes a signal conditioner 180 configured to convert or transform data (e.g., one or more values, one or more temperature values) received from the temperature sensor 148. For example, the signal conditioner 180 may include one or more analogue to digital converters configured to convert analogue values (e.g., temperature values) received from the temperature sensor 148 into digital temperature values.

The memory device 146 may also include a temperature determination module 182 configured to determine temperature of the tube 124 (e.g., one or more tubes) of the second heat exchanger 106 (e.g., condenser). In some embodiments, the HVAC system 100 may include one temperature sensor 148 implemented with second heat exchanger 106 (e.g., condenser). In such embodiments, the temperature determination module 182 may determine that a value received from the temperature sensor 148 is a temperature of the tube 124. In other embodiments, the HVAC system 100 may include multiple temperature sensors 148 implemented with second heat exchanger 106 (e.g., condenser). In such embodiments, the temperature determination module 182 may calculate an average and/or mean value (e.g., average temperature value) of multiple temperature value values received from the multiple temperature sensors 148. The controller 142 may then utilize the calculated average value to derive additional metrics (e.g., pressure value, saturated pressure), evaluate operation of the HVAC system 100, and/or implement subsequent control actions (e.g., adjustments to the compressor 128 and/or the second fan 116). Additionally or alternatively, the temperature determination module 182 may implement any other suitable method (e.g., calculation of weighted averages) to determine and/or produce data (e.g., one or more values) indicative of a temperature of the working fluid and/or indicative of a temperature of the tube 124 based on received temperature values from the temperature sensors 148. Such determined data may then be further utilized to implement one or more of the techniques described herein.

The memory device 146 may include a pressure determination module 184 configured to determine (e.g., derive, calculate, estimate, automatically determine) one or more pressure values of the working fluid (e.g., saturation pressure value) based on the temperature value received via the temperature sensor 148 and/or determined by the temperature determination module 182. In some embodiments, the memory device 146 and/or other portion of the controller 142 may include a database 186 with working fluid reference data stored therein. For example, the working fluid reference data stored in the database 186 may include one or more lookup tables, charts, graphs, and/or other reference data. The working fluid reference data may associate temperature values (e.g., saturated temperature values) and pressure values (e.g., saturated pressure values) for a particular type of the working fluid circulated through the HVAC system 100. In some embodiments, the working fluid reference data may include associated temperature values and pressure values for multiple different types of the working fluid. The pressure determination module 184 may reference the working fluid reference data stored in the database 186 (e.g., stored on the memory device 146) to determine (e.g., calculate, automatically determine, derive) a pressure value (e.g., saturated pressure value) corresponding to the temperature value received via the temperature sensor 148 and/or determined by the temperature determination module 182. As discussed herein, in some embodiments, the temperature sensor 148 may detect and transmit a temperature of the tube 124, which may be considered indicative of (e.g., substantially equivalent to) a saturation temperature of the working fluid directed through the second heat exchanger 106. The pressure determination module 184 may utilize the detected and/or determined saturation temperature of the working fluid and may reference the working fluid reference data stored in the database 186 to determine a corresponding pressure value (e.g., saturated pressure) of the working fluid. In some embodiments, the pressure determination module 184 may implement (e.g., apply) a correction factor and/or may execute arithmetic operations using the temperature value received via the temperature sensor 148 and/or determined by the temperature determination module 182 to determine the saturation temperature and/or the saturation pressure of the working fluid. The correction factor and/or arithmetic operations (e.g., expression(s), formula(s)) may be stored in the database 186, in some embodiments.

The memory device 146 may include a compressor and fan control module 188 configured to control operation of the compressor 128 (e.g., motor 150, VSD 152) and the second fan 118 (e.g., fan motor 154, condenser fan). The control module 188 may execute code and/or implement logic to adjust a frequency (e.g., speed) of the compressor 128 and/or to adjust a speed of the second fan 118. The frequency and/or speed adjustments may be determined by the control module 188 and may correspond to the pressure of the working fluid (e.g., saturation pressure) determined by the pressure determination module 184. In some embodiments, respective adjustments (e.g., adjustment amounts, adjustment values) to the frequency of the compressor 128 and/or the speed of the second fan 118 may be determined based on a comparison of the pressure of the working fluid to one or more threshold values (e.g., threshold pressure values). For example, in response to a determination that the pressure is above a threshold value (e.g., one or more threshold values), the control module 188 may determine that the frequency of the compressor 128 should be reduced and/or the speed of the second fan 118 should be increased. In some embodiments, a frequency reduction amount to be applied to the frequency of the compressor 128 and/or a speed increase amount to be applied to the speed of the second fan 118 may be determined based on (e.g., corresponding to) an amount by which the pressure exceeds a particular threshold value. For example, in response to a determination that the working fluid pressure is above a threshold value, the control module 188 (e.g., controller 142) may determine an amount by which the working fluid pressure exceeds the threshold value, determine a speed increase amount corresponding to the amount by which the pressure exceeds the threshold value, and increase the speed of the second fan 118 by the speed increase amount. Additionally or alternatively, in response to a determination that the working fluid pressure is above a threshold value, the control module 188 (e.g., controller 142) may determine an amount by which the working fluid pressure exceeds the threshold value, determine a frequency reduction amount corresponding to the amount by which the pressure exceeds the threshold value, and reduce the frequency of the compressor 128 by the frequency reduction amount.

Additional examples of control logic that may be implemented are described below.

In some embodiments, a data table may be stored in the database 186. The data table may include instructions (e.g., executable instructions) regarding adjustments (e.g., decreases) to the frequency of the compressor 128 and/or adjustments (e.g., increases) to the speed of the second fan 116 corresponding to various values and/or trends in the pressure of the working fluid. For example, the instructions may include various frequency reduction amounts (e.g., values, adjustments) for the compressor 128 and/or various speed increase amounts (e.g., values, adjustments) for the second fan 118 for different intervals and/or time periods (e.g., threshold time periods) during which the pressure (e.g., saturated pressure) is determined to be above different threshold values, where corresponding values of the frequency reduction amount, speed increase amount, and threshold time period vary as the threshold value varies. In some embodiments, the control module 188 may include mathematical formulae configured to be applied using the working fluid pressure as an input to determine corresponding values of the frequency of the compressor 128 and the speed of the second fan 118 (e.g., condenser fan). The control module 188 may generate control signals for the controller 142 to send to the compressor 40 (e.g., motor 150, VSD 152) and the second fan 118 (e.g., fan motor 154) to reduce the frequency of the compressor 128 and increase the speed of the second fan 118 based on values (e.g., adjustment values, increased values, decreased values) of the frequency of the compressor 128 and the speed of the second fan 118 determined by the controller 142.

In some embodiments, the control module 188 may implement artificial intelligence and/or machine learning techniques to control operation of the compressor 128 and the second fan 118. The control module 188 may determine whether the pressure of the working fluid, the temperature of the tube 124, and/or the temperature of the working fluid exceeds a corresponding limit value (e.g., upper limit value, maximum value). In some embodiments, the control module 188 may vary one or more of the corresponding limit valued (e.g., dynamic limit values) based on various parameters including, but not limited to, service history of the HVAC system 100 and/or components thereof, repair and/or replacement history of the HVAC system 100 and/or components thereof, operational timelines and/or history of the HVAC system 100 and/or components thereof, and so forth. In some embodiments, in response to a determination that the working fluid pressure exceeds a preset (e.g., user defined) threshold value, the control module 188 may refer to the dynamic threshold value for comparison. In some embodiments, the control module 188 may generate and/or report one or more alerts indicating that a threshold value set by the user is exceeded, but that an actual value of the working fluid pressure is within permissible range when factors related to an operational history of the HVAC system 100 and/or components thereof are considered.

In some embodiments, the control module 188 may control operation of the compressor 128 and/or the second fan 118 in response to a determination that the working fluid pressure is approaching a particular threshold value. In some embodiments, the control module 188 may suspend operation of the compressor 128 in response to a determination that the working fluid pressure exceeds a particular threshold value (e.g., upper threshold value, second threshold value greater than a first threshold value, third threshold value greater than a second threshold value) in order to mitigate potential wear and/or degradation to the compressor 128 that may be induced via continued operation of the compressor 128.

In some embodiments, the control module 188 (e.g., controller 142) may be configured to generate control signals to reduce the frequency of the compressor 128 and increase the speed of the second fan 118 simultaneously (e.g., in response to a determination that a saturated pressure of the working fluid exceeds a threshold value). In some embodiments, the control module 188 (e.g., controller 142) may be configured to generate control signals to control the compressor 128 or the second fan 118 according to a hierarchy and/or progressive control scheme. For example, in response to a determination that the pressure of the working fluid (e.g., saturated pressure) exceeds a threshold value, the control module 188 (e.g., controller 142) may initially increase the speed of the second fan 118. Subsequently, the controller 142 may initiate (e.g., start, activate) a timer 190 of the controller 142 to track a threshold time period. The length of the threshold time period may be determined based on a comparison of the threshold value to a desired operation range of the working fluid pressure. In response to lapse of the threshold time period without the working fluid pressure falling below the threshold value, the control module 188 (e.g., controller 142) may implement an adjustment (e.g., decrease) to the frequency of the compressor 128 (e.g. via control of the VSD 152 and/or motor 150).

As discussed herein, the controller 142 may be configured to compare the working fluid pressure (e.g., determined via the pressure determination module 184) with one or more threshold values. In some embodiments, the controller 142 may be configured to implement different control actions (e.g., frequency adjustments, speed adjustments) in response to the working fluid pressure exceeding different threshold values. For example, the controller 142 may be configured to compare the working fluid pressure to a first threshold value and a second threshold value greater than the first threshold value. The controller 142 may be configured to increase the speed of the second fan 118 at a first rate of change in response to a determination that the working fluid pressure is above the first threshold value and below the second threshold value, and the controller 142 may be configured to increase the speed of the second fan 118 at a second rate of change, greater than the first rate of change, in response to a determination that the working fluid pressure is above the second threshold value. Additionally or alternatively, the controller 142 may be configured to reduce the frequency of the compressor 128 at a first (e.g., third) rate of change in response to the determination that the working fluid pressure is above the first threshold value and below the second threshold value, and the controller 142 may be configured to reduce the frequency of the compressor 128 at a second (e.g., fourth) rate of change, greater than the first (e.g., third) rate of change, in response to a determination that the working fluid pressure is above the second threshold value. In some embodiments, the controller 142 may be further configured to compare the working fluid pressure to an additional (e.g., third) threshold value greater than another (e.g., first, second) threshold value and suspend operation of the compressor 128 in response to a determination that the pressure is above the additional threshold value.

In some embodiments, in response to a determination that the working fluid pressure exceeds a threshold value, the controller 142 may be configured to reduce the frequency of the compressor 128 by an amount corresponding to a difference value by which the working fluid pressure exceeds the threshold value. Additionally or alternatively, in response to a determination that the working fluid pressure exceeds a threshold value, the controller 142 may be configured to increase the speed of the second fan 118 by an amount corresponding to a difference value by which the working fluid pressure exceeds the threshold value.

The controller 142 may communicate with a building management system (BMS) associated with the HVAC system 100 or another control system to notify changes in the frequency of the compressor 128 and/or changed in the speed of the second fan 228. The BMS or the HVAC system 100 may display such changes on a user interface or a display unit. In other embodiments of the present disclosure, the controller 142 may utilize directly the temperature data received from the temperature sensor 148 to determine desired changes to the frequency of the compressor 128 and/or to the speed of the second fan 118. For example, the controller 142 may utilize a logic that suggests changes in the frequency of the compressor 128 and/or the speed of the second fan 118 corresponding to the temperature of the tube 124 and/or the temperature (e.g., saturated temperature) of the working fluid.

As set forth above, embodiments of the present disclosure are directed to an HVAC system having a control system configured to operate one or more components of the HVAC system utilizing data and/or feedback from one or more devices that are more cost-effective and/or that may be implemented in HVAC systems with reduced complications. For example, the control system may include a controller and a temperature sensor communicatively coupled to the controller. The temperature sensor may be implemented with a condenser and/or outdoor heat exchanger of the HVAC system. In particular, the temperature sensor may be coupled to (e.g., directly coupled to, attached to) a tube of the condenser. The controller may receive data indicative of a temperature of the condenser and/or working fluid within the condenser (e.g., saturated working fluid temperature) and may adjust operation of one or more components of the HVAC system (e.g., compressor, condenser fan) based on the data (e.g., temperature data). In some implementations, the controller may be configured to manipulate the temperature data to calculate or otherwise determine a pressure (e.g., saturated pressure, condensing pressure, discharge pressure) of the working fluid and then adjust operation of the one or more components of the HVAC system based on the calculated pressure. Additionally or alternatively, the controller may be configured to adjust operation of the one or more components of the HVAC system based on the temperature data and without calculating a pressure of the working fluid. In any case, the disclosed techniques enable desired operational control of the HVAC system without use of costly high-pressure sensors typically included in many HVAC systems. The disclosed techniques also enable a reduction in costs and complexity associated with manufacture, operation, and/or maintenance of the HVAC system. It should be understood that the technical effects and technical problems in the specification are examples and are not limiting. Indeed, it should be noted that the embodiments described in the specification may have other technical effects and can solve other technical problems.

While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, such as temperatures and pressures, mounting arrangements, use of materials, colors, orientations, and so forth, 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 disclosure.

Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode, or those unrelated to enablement. 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.

The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function]. . . ” or “step for [perform]ing [a function]. . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).