The present disclosure relates generally to heating, ventilating, and air conditioning (HVAC) systems, and more particularly to refrigerant leak management for HVAC systems.
Residential, light commercial, commercial, and industrial HVAC systems are used to control temperatures and air quality in residences and buildings. Generally, the HVAC systems may circulate a refrigerant through a closed refrigeration circuit between an evaporator, where the refrigerant absorbs heat, and a condenser, where the refrigerant releases heat. The refrigerant flowing within the circuit is generally formulated to undergo phase changes within the normal operating temperatures and pressures of the system so that quantities of heat can be exchanged by virtue of the latent heat of vaporization of the refrigerant. As such, the refrigerant flowing within a HVAC system travels through multiple conduits and components of the circuit. Inasmuch as refrigerant leaks compromise system performance or result in increased costs, it is accordingly desirable to provide detection and response systems and methods for the HVAC system to reliably detect and respond to any refrigerant leaks of the HVAC system.
In one embodiment of the present disclosure, a refrigerant leak management system for a heating, ventilation, and air conditioning (HVAC) system includes a sleeve member having an inner surface, the sleeve member configured to be disposed over an outer surface of a length of a refrigerant conduit of the HVAC system such that a gap is defined between the inner surface of the sleeve member and the outer surface of the refrigerant conduit. The refrigerant leak management system also includes a fluid moving device configured to fluidly couple to the gap and configured to maintain a sub-barometric pressure within the gap. Additionally, the refrigerant leak management system includes a sensor fluidly coupled to the gap and configured to detect a concentration of a leaked refrigerant in the gap.
In another embodiment of the present disclosure, a heating, ventilation, and air conditioning (HVAC) system includes a refrigerant conduit of a refrigeration circuit and a sleeve member configured to be disposed circumferentially around a length of the refrigerant conduit having an outer surface. A gap is defined between an inner surface of the sleeve member and the outer surface of the refrigerant conduit. The refrigerant sleeve system also includes a fluid moving device fluidly coupled to the gap and configured to maintain a sub-barometric pressure within the gap. Additionally, the refrigerant leak management system includes a sensor fluidly coupled to the gap and configured to detect a concentration of a leaked refrigerant in the gap.
In a further embodiment of the present disclosure, a method of operating a refrigerant leak management system of a heating, ventilation, and air conditioning (HVAC) system of a building includes operating, via a HVAC controller, a fluid moving device to maintain a sub-barometric pressure within a gap defined between an inner surface of a sleeve member and an outer surface of a refrigerant conduit of the HVAC system. The sleeve member circumferentially surrounds a length of the refrigerant conduit of the HVAC system. The method includes determining, via the HVAC controller, a concentration of a leaked refrigerant within the gap based on input from a sensor. Additionally, the method includes modifying, via the HVAC controller, operation of the HVAC system in response to determining that the concentration of the leaked refrigerant is greater than a predefined concentration threshold.
Other features and advantages of the present application will be apparent from the following, more detailed description of the embodiments, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the application.
As discussed above, a HVAC system generally includes a refrigerant flowing within a refrigeration circuit. However, the refrigerant may inadvertently leak from a flow path of the refrigeration circuit due to wear or damage to components, or faulty joints or connections within the refrigeration circuit at some point after installation. If undetected, leaking refrigerant may compromise system performance or result in increased costs. As such, present techniques enable HVAC systems to reliably detect and manage refrigerant leaks.
With the foregoing in mind, present embodiments are directed to a refrigerant leak management system that is capable of detecting and/or mitigating refrigerant leaking from a refrigeration circuit of a HVAC system. The disclosed refrigerant leak management system includes at least one refrigerant conduit sleeve positioned around at least one refrigerant conduit of the refrigeration circuit of the HVAC system. A gap or space is defined between an interior surface or boundary of the sleeve and an exterior surface or boundary of the refrigerant conduit. A fan or other suitable fluid moving device is fluidly coupled to, and maintains a sub-barometric pressure within, this gap. The fan generally draws air from the gap of the sleeve near a refrigerant gas concentration sensor, or other suitable detection mechanism, before driving the air into an environment outside of the sleeve. A controller is communicatively coupled to the refrigerant gas concentration sensor and generally determines whether a refrigerant leak is present in the HVAC system based on measurement data received from the refrigerant gas concentration sensor. Additionally, the controller may instruct portions of the refrigerant leak management system and/or the HVAC system to take corrective action to mitigate the refrigerant leak. For example, in response to a refrigerant leak, the controller may increase air flow through the sleeve to drive leaked refrigerant from the gap. In this manner, the disclosed techniques enable detection of refrigerant leak within the HVAC system, and enable response via any combination of suitable control actions to address the leaked refrigerant.
Turning now to the drawings,
The HVAC unit 12 is an air cooled device 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 refrigeration circuit configured to operate in different modes. In other embodiments, the HVAC unit 12 may include one or more refrigeration 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.
As shown in the illustrated embodiment of
The HVAC unit 12 includes heat exchangers 28 and 30 in fluid communication with one or more refrigeration circuits. Tubes within the heat exchangers 28 and 30 may circulate refrigerant through the heat exchangers 28 and 30. For example, the refrigerant may be R-410A. 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 refrigerant 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 refrigerant to ambient air, and the heat exchanger 30 may function as an evaporator where the refrigerant 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
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 rooftop 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 refrigerant before the refrigerant 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.
When the system shown in
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 air conditioning mode. Thereafter, the air is passed through ductwork 68 that directs the air to the residence 52. The overall system operates to maintain a desired temperature as set by a system controller. When the temperature sensed inside the residence 52 is higher than the set point on the thermostat, or the set point plus a small amount, the residential heating and cooling system 50 may become operative to refrigerate additional air for circulation through the residence 52. When the temperature reaches the set point, or the set point minus a small amount, the residential heating and cooling system 50 may stop the refrigeration cycle temporarily.
The residential heating and cooling system 50 may also operate as a heat pump. When operating as a heat pump, 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 refrigerant and thereby cool air entering the outdoor unit 58 as the air passes over outdoor the 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 refrigerant.
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 residential heating and cooling system 50 is not configured to operate as a heat pump. The furnace system 70 may include a burner assembly and heat exchanger, among other components, inside the indoor unit 56. Fuel is provided to the burner assembly of the furnace 70 where it is mixed with air and combusted to form combustion products. The combustion products may pass through tubes or piping in a heat exchanger that is separate from heat exchanger 62, such that air directed by the blower 66 passes over the tubes or pipes and extracts heat from the combustion products. The heated air may then be routed from the furnace system 70 to the ductwork 68 for heating the residence 52.
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 refrigerant 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 refrigerant 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 refrigerant vapor may condense to a refrigerant liquid in the condenser 76 as a result of thermal heat transfer with the environmental air 96. The liquid refrigerant from the condenser 76 may flow through the expansion device 78 to the evaporator 80.
The liquid refrigerant 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 residence 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 refrigerant in the evaporator 80 may undergo a phase change from the liquid refrigerant to a refrigerant vapor. In this manner, the evaporator 38 may reduce the temperature of the supply air stream 98 via thermal heat transfer with the refrigerant. Thereafter, the vapor refrigerant exits the evaporator 80 and returns to the compressor 74 by a suction line to complete the cycle.
In some embodiments, the vapor compression system 72 may further include a reheat coil in addition to the evaporator 80. For example, the reheat coil may be positioned downstream of the evaporator relative to the supply air stream 98 and may reheat the supply air stream 98 when the supply air stream 98 is overcooled to remove humidity from the supply air stream 98 before the supply air stream 98 is directed to the building 10 or the residence 52.
It should be appreciated that any of the features described herein may be incorporated with the HVAC unit 12, the residential heating and cooling system 50, or other HVAC systems. Additionally, while the features disclosed herein are described in the context of embodiments that directly heat and cool a supply air stream provided to a building or other load, embodiments of the present disclosure may be applicable to other HVAC systems as well. For example, the features described herein may be applied to mechanical cooling systems, free cooling systems, chiller systems, or other heat pump or refrigeration applications.
Moreover, the illustrated embodiment of the HVAC system 100 conditions a building 10, such as the residence 52 discussed above, by providing conditioned air to an interior of the building 10. As shown, the expansion device 78 and the evaporator 80 are located or positioned within the building 10 and the compressor 74 and the condenser 76 are located or positioned outside of the building 10. For example, the expansion device 78 and the evaporator may be part of the indoor HVAC unit 56, while the compressor 74 and the condenser 76 may be part of the outdoor HVAC unit 58 of the residential heating and cooling system 50, as discussed above with respect to
Additionally, the illustrated embodiment of the refrigerant leak management system 102 in
The disclosed sleeves 112 may be any suitable tubular members or conduits of sufficient size for receiving the conduits 110 therein. In embodiments in which one of the sleeves 112 extends over other components such as the expansion device 78, a portion of the sleeve extending over the other component may have an increased circumferential size as compared to other portions of the sleeves 112 of the refrigerant leak management system 102. Thus, the sleeves 112 may circumferentially surround the conduits 110 to capture a leak of the refrigerant 104 therein. In particular, a gap 145 is defined between an interior surface or boundary of each sleeve and an exterior surface or boundary of the conduit. In some embodiments, this gap 145 between respective sleeves and respective conduits includes an interior volume 146 therein. Under certain conditions, refrigerant 104 leaking from the conduits 110 thus enters the gap 145 of the sleeves 112.
In some embodiments, the sleeves 112 may be formed of a strong and/or rigid material, such as plastic, metal, alloy, concrete, ceramic, or the like. Thus, the sleeves 112 may protect the conduits 110 from structural damage via puncturing, compressing, crimping, vibrations, or the like. Additionally or alternatively, in some embodiments, the sleeves 112 may be formed from or include a thermally insulated material to further reduce heat transfer between the conduits 110 and an environment around the conduits 110, as compared to thermal insulation provided by air within the gap between the sleeves 112 and the conduits 110. For example, the sleeves 112 may include insulation disposed around an outer surface of the sleeves 112, or may be entirely formed from a thermally insulated material. The insulation or the thermally insulated materials may be formed of such materials as foam, fiberglass, rubber, plastic, or the like.
Additionally, the illustrated embodiment of the refrigerant leak management system 102 employs suitable fluid moving devices, such as illustrated fans 140 that are communicatively coupled to an electronic controller 144, or other suitable control circuitry, to maintain a target sub-barometric pressure within the sleeves 112. In certain embodiments, the fans 140 are free of activation sources and/or are driven by motors that are free of activation sources, such as sparks. It is to be understood that the sub-barometric pressure may include any suitable pressure less than barometric pressure at a location having the refrigerant leak management system 102, including negative or vacuum pressures. For example, the fans 140 may maintain the sub-barometric pressure within the sleeves 112 at 99.5 percent of the barometric pressure, 99.0 percent of the barometric pressure, 98.5 percent of the barometric pressure, 98.0 percent of the barometric pressure, 95.0 percent of the barometric pressure, 90.0 percent of the barometric pressure, or lower; or at 0.995 atm, 0.990 atm, 0.985 atm, 0.980 atm, 0.950 atm, 0.900 atm, or lower. Focusing the discussion on the first sleeve 116, the fan 140 may be embedded in a surface of the first sleeve 116, or otherwise fluidly coupled to the first sleeve 116. By drawing air from the gap 145 or annular space defined between the inner surface of the first sleeve 116 and the outer surface of the first conduit 118, the fan 140 maintains the sub-barometric pressure within this gap 145 of the first sleeve 116. Then, the air passes through the fan 140 and into an external environment 150.
By transmitting control signals to the fan 140, the illustrated controller 144 operates the fan to maintain the sub-barometric pressure within the first sleeve 116. As illustrated, the fans 140 are similarly fluidly coupled to the respective gap 145 of other sleeves 112 of the refrigerant leak management system 102 to maintain a sub-barometric pressure within the other sleeves 112 as well. In some embodiments, a common or shared sub-barometric pressure is maintained in each of the sleeves 112 using a common or shared fluid moving device. However, the target sub-barometric pressure for each of the sleeves 112 may be predetermined based on relevant parameters of the HVAC system 100, such as flowrates, pressures, temperatures, outside air temperature, etc. Although described herein as employing fans 140, the refrigerant leak management system 102 may, additionally or alternatively, use other fluid moving devices, such as blowers, vacuum pumps, compressors, or other devices capable of moving any suitable fluid from one environment to another environment. Further, in certain embodiments, a pressure sensor or a flowrate sensor communicatively coupled to the controller 144 is fluidly coupled to the gap 145 of each of the sleeves 112 to transmit signals indicative of the pressure within each of the sleeves 112. In such embodiments, the controller 144 may verify the pressure within the gap 145 and adjust the pressure to be within a threshold of the target sub-barometric pressure based on sensor feedback. In certain embodiments, the refrigerant leak management system 102 may also include pressure-relief devices, such as rupture discs and/or pressure relief valves, coupled to the sleeves 112 at positions that are outside of the building 10. As such, in response to the pressure within the sleeves 112 exceeding a predetermined pressure threshold, the pressure-relief devices may open due to over pressuring and fluidly couple the gap 145 to the external environment 108.
Moreover, the embodiment of the refrigerant leak management system 102 illustrated in
The concentration sensors 142 may be any type of concentration sensors, including electrochemical gas detectors, catalytic bead sensors, photoionization detectors, infrared point sensors, infrared imaging sensors, semiconductor sensors, ultrasonic gas detectors, holographic gas sensors, or any other suitable concentration sensor capable of detecting a concentration of the refrigerant 104. Additionally, each of the sleeves 112 may include a different concentration sensor 142 that is preselected based on parameters of the HVAC system, such as nearby equipment, available power supply, or other considered parameters. Moreover, although discussed herein as having concentration sensors 142, the refrigerant leak management system 102 may, additionally or alternatively, include other sensors suitable for detecting a presence of the refrigerant 104 within the sleeves 112, such as temperature sensors, pressure sensors, acoustic sensors, flowrate sensors, etc.
The controller 144 receives the signals from the concentration sensors 142 indicative of the concentration of the refrigerant 104 within the gap 145 defined between the conduits 110 and the sleeves 112. Then, based on the signals, the controller 144 determines the concentration of the refrigerant 104. For example, during operation of the HVAC system 100, a leak of the refrigerant 104 may not be present. Thus, if no leak of the refrigerant 104 is present, the controller 144 may determine that the concentration of the refrigerant 104 is below a lower management limit of the concentration sensors 142. However, when refrigerant 104 leaks from a conduit 110 and is drawn across the concentration sensor 142 by the fan 140, the controller 144 receives the signals and determines a non-zero concentration of the refrigerant 104 within the sleeves 112 around the conduits 110.
Additionally, the controller 144 compares the concentration of the refrigerant 104 to a predefined concentration threshold. The predefined concentration threshold may be a user-set, technician-set, or distributor-set value that is stored within the controller 144, either before or after the controller 144 is placed into operation within the HVAC system 100. In response to determining that the concentration of the refrigerant 104 is less than or equal to the predefined concentration threshold, the controller 144 continues to operate the fans 140 to maintain the sub-barometric pressure, and continues to determine the concentration of the refrigerant 104. In some embodiments, rather than continuously measure, the controller 144 and the concentration sensors 142 may also wait a predefined time threshold before determining the concentration of the refrigerant 104 again, thus enhancing sensor life. In certain embodiments, the predefined time threshold is set as 1 minute, 5 minutes, 10 minutes, 60 minutes, or more.
In certain embodiments, in response to determining that the concentration of the refrigerant 104 is greater than the predefined concentration threshold, the controller 144 provides a control signal modifying operation of the HVAC system 100. The control signal modifies the HVAC system 100 to provide alerts and/or perform mitigating actions in response to a detected refrigerant leak. For example, the control signal may instruct the HVAC system 100 to stop operating or to stop driving the compressor 74. Suitable alerts may include notice of the concentration of the refrigerant 104 that is greater than the predefined concentration threshold. Additionally, the controller 144 may transmit the control signal to instruct a device, such as a thermostat, a user device, and/or a service technician workstation, to generate an alert indicative of the detected refrigerant leak, which includes instructions to deactivate activation sources and/or to instruct users to respond appropriately. Once informed of the detected refrigerant leak, users may perform manual control actions, such as shutting off the HVAC system 100 or repairing a conduit 110 responsible for the detected refrigerant leak.
Additionally, the control signal may automatically modify operation of the refrigerant leak management system 102 to mitigate the detected refrigerant leak. For example, the control signal may instruct the fans 140 at an increased flowrate compared to a normal flowrate of the fans 140 used to maintain the sub-barometric pressure within the sleeves 112. Thus, the fans 140 may drive more air through the gap 145 of the sleeves 112 and direct the resulting mixture of air and leaked refrigerant 106 into the external environment 150, which may be outside the building 10 associated with the HVAC system 100. In this manner, control signals provided by the controller 144 may operate the refrigerant leak management system 102 to dilute, remove, or mitigate refrigerant 104 sourced from the detected refrigerant leak until the detected refrigerant leak is resolved. Moreover, one or more of the above modifications to the refrigerant leak management system 102 and/or the HVAC system 100 may be performed simultaneously or within a time threshold to more rapidly respond to the detected refrigerant leak. Additionally, in some embodiments, the controller 144 may block the HVAC system 100 from operating or entering ON-cycle until after the concentration of the refrigerant is again within the predefined concentration threshold, or until after the detected refrigerant leak is repaired.
In some embodiments, the controller 144 may employ a feedback loop to adjust the modifications to the HVAC system 100. That is, the controller 144 may implement a dynamic response strategy that monitors the concentration of the refrigerant 104 after the refrigerant leak is detected to evaluate an effectiveness of the modifications to the HVAC system 100, and the controller 144 may further modify and/or adjust operation of the HVAC system 100 based on the determined effectiveness. For example, in certain embodiments, after determining that the concentration of the refrigerant 104 in the first sleeve 116 is above the predefined concentration threshold, the controller 144 may instruct the fan 140 of the first sleeve 116 to increase a flowrate of air through the fan 140 and the first sleeve 116. Then, the controller 144 may receive additional signals indicative of the concentration of the refrigerant 104 in the first sleeve 116 from the concentration sensor 142. Such signals may be received, for example, continuously, at regular intervals, every minute, every ten minutes, or the like. If the controller 144 determines that the concentration of the refrigerant 104 has dropped or is dropping below the predefined concentration threshold, the controller 144 may instruct the fan 140 to return to a normal operating flowrate. However, if the controller 144 determines that the concentration of the refrigerant 104 is still above the predefined concentration threshold, or determines that the concentration is still increasing after a threshold amount of time, the controller 144 may instruct the fan 140 and/or other features of the sleeve 116 to further increase the flowrate of air therethrough. The dynamic response strategy may be implemented across any range of flowrates that the fans 140 may produce. Thus, the controller 144 controls the refrigerant leak management system 102 to both detect and mitigate detected refrigerant leaks from the HVAC system 100 to block or prevent the refrigerant 104 from reaching the predefined concentration threshold.
In the embodiment illustrated in
The processor 156 illustrated in
Although the controller 144 has been described as having the processor 156 and the memory 158, it should be noted that the controller 144 may include or be communicatively coupled to a number of other computer system components to enable the controller 144 to control the operations of the HVAC system 100 and the related components. For example, the controller 144 may include a communication component that enables the controller 144 to communicate with other computing systems. The controller 144 may also include an input/output component that enables the controller 144 to interface with users via a graphical user interface or the like. In addition, the communication between the controller 144 and other components of HVAC system 100 may be via a wireless connection, such as through Bluetooth® Low Energy, ZigBee®, WiFi®, or may be a or wired connection, such as through Ethernet. In some embodiments, the controller 144 may include a laptop, a smartphone, a tablet, a personal computer, a human-machine interface, or the like. In some embodiments, the embodiments disclosed herein may be at least partially embodied using hardware implementations. For example, logic elements of the controller 144 may include a field-programmable gate array (FPGA), or other specific circuitry.
For the illustrated embodiment, a fan 220 is embedded within the sleeve 200, such that the fan 220 maintains the sub-barometric pressure within the gap 145. For example, the fan 220 extends through or traverses the sleeve 200 to fluidly couple the gap 145 of the sleeve and the external environment 108. Moreover, a concentration sensor 222 is embedded within or disposed within and extending through a wall of the sleeve 200 to transmit signals to the controller 144 of
In certain situations, as discussed above, the refrigerant 104 may leak from the conduit 202 as leaked refrigerant 106 that enters the gap 145 within the sleeve 200. As discussed, the sub-barometric pressure within the gap 145 encourages the leaked refrigerant 106 to flow an axial direction 206 within the sleeve 200, proximate the concentration sensor 222, through the fan 220, and into the external environment 108. Thus, the refrigerant leak management system 102 detects and mitigates the leaked refrigerant 106 concentration before a buildup to the predefined concentration threshold may occur.
Looking along the 7-7 line of
To also fluidly couple the gap 145 to the external environment 108, the embodiment of the refrigerant leak management system 102 illustrated in
Upon instruction from the controller 144, the air intake regulation device 252 may adjust a position of the slats 254 to vary the size of an intake opening between the external environment 108 and the gap 145. In some embodiments, the slats 254 are adjustable between completely closed, partially opened, and/or completely open positions. When in a completely or partially open state, air removed from the gap 145 by the fan 220 is replaced by air drawn in through the air intake regulation device 252. For example, when the slats 254 are in a fully open position, the intake opening between the external environment 108 and the gap has a maximum size, such that more air is replaced through the opening than when the slats 254 were in a partially open position or a fully closed position. Moreover, in certain embodiments, even when the air intake regulation device 252 is in the fully closed position, the air intake regulation device 252 the sleeve 200, and/or joints of the sleeve 200 may enable a limited amount of air to enter the sleeve 200, such that the fan 220 is capable of maintaining the sub-barometric pressure in such embodiments. Although discussed as the air intake regulation device 252, any suitable component for fluidly coupling the gap 145 to the external environment 108 may be provided in place of the air intake regulation device 252, including a cutout from the sleeve 200, an opening, a port, static louvers, jalousies, a mechanically controlled hatch, a valve, etc. Additionally, the air intake regulation device 252 may be fluidly coupled to the sleeve 200 by any suitable means instead of being embedded within the sleeve 200, such as by an adjoining sleeve fluidly coupled to the sleeve 200.
For the embodiment illustrated in
Additionally, in various embodiments, the sleeve 200 may be installed around the conduit 202 by one of multiple processes. As discussed, the conduit 202 is fluidly coupled to other components of the refrigeration system, and thus, is rigidly attached at both ends 258 of the conduit 202 to the other components. In some embodiments, the sleeve 200 may be loosely disposed around the conduit 202 before the ends 258 of the conduit 202 are coupled to the other components. Additionally, in some embodiments, the sleeve 200 may be separable into multiple longitudinal sections 270 which snap or fasten together at corresponding ends of the longitudinal sections to form the continuous sleeve 200, and the longitudinal sections 270 of the sleeve 200 are snapped together around the conduit 202 before or after the ends 258 of the conduit 202 are coupled to the other components. In certain embodiments, the longitudinal sections 270 are coupled together at a joint 272. The joint 272 may be formed from any suitable coupling means, including corresponding threaded portions disposed on the longitudinal sections 270, an outer cuff disposed over end portions of the longitudinal sections 270 to couple the longitudinal sections 270 together, etc. Additionally, the sleeve 200 may be secured around the conduit 202 via any suitable mating/attachment features, such as raised alignment features coupled to or integrally formed with the conduit 202, and corresponding recessed alignment features disposed within the sleeve 200.
As discussed herein, a proximate portion 259 of the sleeve 200 includes the fan 220 and the concentration sensor 222, while a distal portion 261 of the sleeve 200 includes the air intake regulation device 252. Additionally, ends 260 of the sleeve 200 may remain unattached from the other components of the refrigeration circuit and the conduit 202 to enable the conduit 202 to thermally expand relative to the sleeve 200 based on operation of the HVAC system 100. For example, the illustrated conduit 202 has a conduit length 264 that is longer than a sleeve length 262 of the sleeve 200. The difference between the conduit length 264 and the sleeve length 262 may be preselected based on thermal expansion properties of the conduit 202 and the sleeve 200, and based on properties of the refrigerant within the conduit 202. For example, if the conduit 202 is capable of contracting in size during operation of the HVAC system 100, such as due to cold and/or condensed refrigerant flowing through the conduit 202, the difference between the conduit length 264 and the sleeve length 262 may be designed such that contraction of the conduit 202 does not affect placement of the sleeve 200. Moreover, the ends 260 of the sleeve 200 may be sealed by any suitable means, including sealing members 280 such as annular sealing members, gaskets, caps, epoxy deposits, or the like.
In case of a refrigerant leak, the refrigerant is expected to be denser than the ambient air within the sleeve 200, and sink to the bottom portion 304 of the sleeve 200. As such, placing the fan 220 in the bottom portion 304 of the sleeve 200 may enable the fan 220 to more rapidly purge the leaked refrigerant 106 to the external environment 108. However, because the fan 220 maintains a sub-barometric pressure within the sleeve 200, the fan 220 may be fluidly coupled to the gap 145 within the sleeve 200 from any position. That is, the fan 220 may be powerful enough to remove the leaked refrigerant 106 from the sleeve 200 from any suitable, fluidly coupled location.
Indeed, for the embodiment of the sleeve 200 illustrated in
As shown, a lower inner portion 322 of the sleeve 200 may be in contact with a lower outer portion 324 of the conduit 202. In such embodiments, the lower inner portion 322 of the sleeve 200 may be attached to the lower outer portion 324 of the conduit 202 by any suitable attachment means, such as via fasteners, adhesive, etc. In some embodiments, the distal ends of the sleeve 200 and the distal ends of the conduit 202 may be attached to the other components of the HVAC system 100, such that attachment between the sleeve 200 and the conduit 202 is not necessary to maintain the lower inner portion 322 of the sleeve 200 and the lower outer portion 324 of the conduit 202 in contact.
As previously mentioned, the refrigerant leak management system 102 may also serve as insulation and/or physical protection for the conduit 202. For example, as shown in
Moreover, in some embodiments, the HVAC system 100 may be retrofitted with the refrigerant leak management system 102. For example, the thick sleeve 350 may be installed around an existing conduit 202 of the HVAC system 100, and then a fan 358 and a concentration sensor 222 may be embedded or otherwise fluidly coupled to a first end of the thick sleeve 350, while the air intake regulation device 252 or another suitable air inlet may be disposed at a second end of the thick sleeve 350. Additionally, the thick sleeve 350 may protect the conduit 202 from damage by impact, punctures, vibrations, etc. However, an outer layer of structural supporting material, such as metal or plastic, may also be used to increase a damage resistance of the thick sleeve 350.
Looking now to
To begin the illustrated process 400, the controller 144 provides a control signal to activate a fluid moving device, such as the fan 140, fluidly coupled to the gap 145 of the first sleeve 116, as indicated in block 402. For example, the controller 144 may instruct the fan 140 to operate at a predetermined speed or rotational rate to move air out of the gap 145 of first sleeve 116 disposed around the first conduit 118. By moving the air out of the first sleeve 116, the fan 140 maintains the sub-barometric pressure within the gap 145 of the sleeve. Moreover, in certain embodiments, the refrigerant leak management system 102 includes a pressure or flowrate sensor that measures the pressure within the gap 145 of the first sleeve 116, so that the controller 144 can verify and adjust the pressure within the gap 145 to the target sub-barometric pressure.
As indicated in block 404, the controller 144 receives a signal indicative of a concentration of leaked refrigerant 106 within the gap 145 of the first sleeve 116. The concentration sensor 142 fluidly coupled to the gap 145 of the first sleeve 116 may transmit the signal indicative of the concentration of the refrigerant 104 to the controller 144. Indeed, the concentration sensor 142 may transmit the signal continuously, at regular intervals, or after detecting a change in the concentration of the refrigerant 104 within the gap 145 of the first sleeve 116. Following the process 400, the controller 144 also determines the concentration of leaked refrigerant 106 within the gap 145 of the first sleeve 116, as indicated in block 406. For example, the controller 144 may determine the concentration of leaked refrigerant 106 within the gap 145 of the first sleeve 116 based on the signal transmitted from the concentration sensor 142.
The illustrated process 400 further includes the controller 144 determining whether the concentration of leaked refrigerant 106 within the gap 145 is greater than the predefined concentration threshold, as indicated in block 408. For example, the predefined concentration threshold may be a parameter stored within the memory 158 of the controller 144, as discussed above. In response to determining that the concentration of the refrigerant 104 is less than the predefined concentration threshold, the controller 144 may return to block 404 to continue receiving the signal indicative of the concentration of the refrigerant.
In response to determining that the concentration of leaked refrigerant 106 within the gap 145 is greater than the predefined concentration threshold, the controller 144 provides a control signal to modify operation of the HVAC system 100, as indicated in block 410. For example, the control signal from the controller 144 may cause the components of the HVAC system 100 to perform any suitable control actions, such as transmitting an alert indicative of the concentration of leaked refrigerant 106 to a user or to a service technician, ceasing operation of the HVAC system 100, and/or increasing a speed of the fan 140. In general, a concentration of leaked refrigerant 106 that exceeds the predefined concentration threshold is indicative of a leak of the refrigerant 104 from the refrigeration circuit 72. Thus, the control signal from the controller 144 instigates control actions which inform users or service technicians of the refrigerant leak and/or control actions that address the leaked refrigerant 106.
To perform feedback control of the refrigerant leak management system 102, the controller 144 determines the concentration of leaked refrigerant 106 in the gap 145 again, as indicated in block 412. In certain embodiments, the controller 144 determines the concentration of leaked refrigerant 106 in the gap 145 again after a threshold amount of time has passed, after receiving another signal from the concentration sensor 142, etc. Then, the controller 144 determines whether the concentration of the refrigerant 104 is improving, as indicated in block 414. For example, the concentration of the refrigerant 104 may be improving when the concentration of the refrigerant 104 is decreasing from the initial detected concentration, decreasing below the predefined concentration threshold, and/or has a rate of change greater than a rate of change threshold.
In response to determining that the concentration of the refrigerant is improving, the controller 144 continues to provide control signals to modify operations of the HVAC system 100, such as instructing the supply fan to purge the first sleeve 116, as indicated in block 416. In response to determining that the concentration of the refrigerant is not improving, the controller 144 provides control signals to escalate the response to further modify operation of the HVAC system 100, as seen in block 418. For example, the escalating response may include increasing the flowrate through the first sleeve 116 by instructing the fan 140 to increase a speed thereof or instructing an air intake regulation device to enable more air to enter the first sleeve, thus increasing a rate at which the leaked refrigerant is purged from the first sleeve 116. Accordingly, as discussed above, the control signals from the controller 144 are capable of escalating control actions to detect and mitigate leaks of the refrigerant 104 of varying severities.
The present disclosure is directed to a refrigerant leak management system for detecting and mitigating refrigerant leaks. The refrigerant leak management system includes at least one sleeve disposed around one or more refrigerant conduits that fluidly couple components of a HVAC system. The refrigerant leak management system may include thermally insulating and/or structurally sound materials to enhance the efficiency, strength, and/or operational lifetime of the HVAC system. The refrigerant leak management system also includes a fan fluidly coupled to a gap defined between a respective sleeve and a respective conduit, and a concentration sensor that transmits signals indicative of the concentration of the refrigerant within the gap to a controller. The controller monitors the concentration of the refrigerant, and in response to determining that the concentration exceeds a predetermined concentration threshold, the controller provides a control signal to modify operation of the HVAC system. For example, the control signal may cause a device to transmit an alert indicative of the concentration of the refrigerant, stop operation of the HVAC system, and/or cause the fan and/or louvers to increase a flowrate of air therethrough. In this manner, the refrigerant leak management system may improve operation of the HVAC system while enabling the detection and mitigation of refrigerant leaks substantially before the refrigerant may reach the predefined concentration threshold.
While only certain features and embodiments of the present disclosure 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 including temperatures, pressures, etc., mounting arrangements, use of materials, orientations, etc., without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure. Furthermore, in an effort to provide a concise description of the embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode of carrying out the disclosure, or those unrelated to enabling the claimed features. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.
This application is a Non-Provisional application claiming priority to U.S. Provisional Application No. 62/593,557, entitled “SYSTEMS AND METHODS FOR LEAK MANAGEMENT UTILIZING SUB-BAROMETRIC REFRIGERANT CONDUIT SLEEVES,” filed Dec. 1, 2017, which is hereby incorporated by reference in its entirety for all purposes.
Number | Date | Country | |
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62593557 | Dec 2017 | US |