Patent Publication Number: US-11397017-B2

Title: System and method for sealing and supporting external pipe connections in fluid lines and directing escaped fluids to a cabinet in an HVAC system

Description:
TECHNICAL FIELD 
     This disclosure relates generally to heating, ventilation and air conditioning (HVAC) systems such as heat pumps and air handling systems. More specifically, this disclosure relates to a system and method for sealing external pipe connections to prevent fluid leakage and ensuring all system fluids remain contained within the system. 
     BACKGROUND 
     Heating, ventilation, and air conditioning (“HVAC”) systems can be used to regulate the environment within an enclosed space. Frequently, components are housed in a cabinet to protect the components and to present a more aesthetically appearance for customers, and a technician brazes connections between external pipes to stub pipes extending from the HVAC cabinet to interconnect internal components with other equipment in the HVAC system. 
     SUMMARY OF THE DISCLOSURE 
     HVAC systems rely on pressure and temperature differentials related to refrigerants in a refrigeration cycle to efficiently heat and cool air. Traditional refrigerants, although great for the HVAC system, have been scrutinized for their impact on the environment and are presently being replaced by newer refrigerants called A2L refrigerants. New Underwriter Laboratories (UL) safety standards are being updated with requirements to address the use of A2L refrigerants in air conditioning and refrigeration systems. While these new refrigerants may be beneficial to the environment, they also present an increased flammability risk. A proposed regulation would require all connections be contained within the confines of an HVAC cabinet, where sensors and mitigation systems can be implemented to address the flammability risk. However, this proposed solution is likely to cause cabinets to be larger to accommodate the connections and the additional sensors and mitigation systems for the A2L refrigerants. In certain placements, this proposed solution will require modification of an area in which an older HVAC system is replaced and/or will require modification of existing fluid lines and structures through which fluid lines run. 
     Embodiments disclosed herein are generally directed to system and methods for sealing external pipe connections in HVAC systems and ensuring any fluid that escapes near the connection is directed into a cabinet to facilitate detection and mitigation of risks related to the presence of the fluids. 
     Embodiments disclosed herein are generally directed to a stub pipe housing for preventing fluid escaping a connection in a fluid line. The stub pipe housing has a first end for sealed contact with a cabinet and a second end configured for sealed contact with an external pipe connected to the stub pipe. The first end comprises an inner diameter greater than at least an opening for a stub pipe extending from the cabinet and the stub pipe housing comprises a non-permeable inner surface formed between the first end and the second end such that the sealed contact between the first end and the cabinet, the sealed contact between the second end and the external pipe and the non-permeable inner surface of the stub pipe housing direct fluid escaping the connection into an opening in the cabinet. In some embodiments, the first end comprises a flange extending radially outward as a surface and the stub pipe extends through a stub pipe opening in the cabinet such that sealed contact between the stub pipe housing and the cabinet comprises contact between the surface of the flange and an external surface of the cabinet. The sealed contact between the flange and the external surface of the cabinet, the sealed contact between the second end and the external pipe and the non-permeable inner surface of the stub pipe housing direct fluid escaping the connection into an opening in the cabinet. In some embodiments, the first end comprises a flange extending radially outward as an edge and the stub pipe extends through a stub pipe opening in the cabinet such that sealed contact between the stub pipe housing and the cabinet comprises contact between the edge of the flange and an external surface of the cabinet. The sealed contact between the flange and the cabinet comprises a seal positioned in the stub pipe opening and the edge of the flange seated in the seal. In some embodiments, the stub pipe extends through a first opening in the cabinet, the external surface comprises a second opening separate from the first opening and the first end of the stub pipe housing comprises an inner diameter adapted for sealed contact with an external surface of the cabinet relative to one or more of the first opening and the second opening. In some embodiments, the non-permeable inner surface comprises an elastomeric material. In some embodiments, the second end comprises one of a compliant seal formed with an inner diameter less than an outer diameter of the external pipe, a compliant seal and hardware for clamping the compliant seal to the external pipe, or a compliant seal and a circumferential groove or rib for seating the compliant seal against the external pipe. In some embodiments, the stub pipe housing comprises a rigid material and the second end comprises a compliant seal. The stub pipe housing prevents bending at the connection between the stub pipe and the external pipe. 
     Embodiments disclosed herein are also generally directed to a method for directing fluid escaping a connection between an external pipe and a stub pipe to a cabinet in an HVAC system. The method comprises positioning a stub pipe housing on the external pipe, wherein the stub pipe housing comprises an inner diameter greater than at least an opening for a stub pipe extending from the cabinet and a second end adapted for contact with the external pipe. Once the connection between the stub pipe and the external pipe is formed, the method comprises forming a sealed contact between the first end of the stub pipe housing and the cabinet. The sealed contact between the first end and the cabinet, the sealed contact between the second end and the external pipe and the non-permeable inner surface of the stub pipe housing direct fluid escaping the connection into an opening in the cabinet. In some embodiments, the first end comprises a flange extending radially outward as a surface and the stub pipe extends through a stub pipe opening in the cabinet and sealing the connection comprises coupling the surface of the flange to an external surface of the cabinet. In some embodiments, the first end comprises a flange extending radially outward as an edge, the stub pipe extends through a stub pipe opening in the cabinet and sealing the connection comprises positioning a seal in the stub pipe opening and seating the edge of the flange in the seal. In some embodiments, configuring the stub pipe housing for sealed contact with the external pipe comprises one of positioning the second end on the external pipe, wherein the second end of the stub pipe housing comprises a compliant seal formed with an inner diameter less than an outer diameter of the external pipe, clamping a compliant seal to the external pipe, or seating a compliant seal in a circumferential groove or against a circumferential rib. 
     Embodiments disclosed herein are also generally directed to an HVAC system with a compressor, an evaporator and a condenser forming a refrigeration cycle and a plurality of fluid lines coupled to the compressor, the evaporator and the condenser, wherein each connection between a fluid line and one of the compressor, the evaporator and the condenser represents a point at which fluid can escape the HVAC system. For each stub pipe in the HVAC system a stub pipe housing is coupled to prevent fluid leakage and to direct any fluids escaping connections between the stub pipes and the external pipes. Each stub pipe housing comprises a first end for sealed contact with a cabinet, wherein the first end comprises an inner diameter greater than at least an opening for a stub pipe extending from the cabinet; and a second end configured for sealed contact with an external pipe connected to the stub pipe. The stub pipe housing comprises a non-permeable inner surface formed between the first end and the second end such that the sealed contact between the first end and the cabinet, the sealed contact between the second end and the external pipe and the non-permeable inner surface of the stub pipe housing direct fluid escaping the connection into an opening in the cabinet. In some embodiments, the first end of at least one stub pipe housing comprises a flange extending radially outward as a surface, the stub pipe extends through a stub pipe opening in the cabinet and sealed contact between the stub pipe housing and the cabinet comprises contact between the surface of the flange and an external surface of the cabinet. In some embodiments, the first end comprises a flange extending radially outward as an edge, the stub pipe extends through a stub pipe opening in the cabinet and sealed contact between the stub pipe housing and the cabinet comprises a seal positioned in the stub pipe opening and the edge of the flange seated in the seal. In some embodiments, the second end comprises one of a compliant seal formed with an inner diameter less than an outer diameter of the external pipe, a compliant seal and hardware for clamping the compliant seal to the external pipe, or a compliant seal and a circumferential groove or rib for seating the compliant seal against the external pipe. In some embodiments, at least one stub pipe housing comprises a rigid material and a respective second end of the stub pipe housing comprises a compliant seal such that coupling the second end of the stub pipe housing to an external pipe prevents bending at the connection between the stub pipe and the external pipe. 
     Certain embodiments may include none, some, or all of the above technical advantages. One or more other technical advantages may be readily apparent to one skilled in the art from the figures, descriptions, and claims included herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  depicts an architectural diagram of an exemplary heating, ventilation, and air conditioning (“HVAC”) system; 
         FIG. 2  depicts a perspective view of an exemplary cabinet in an HVAC system, illustrating a positioning of selected HVAC components and their proximity to stub pipes; 
         FIG. 3  depicts a cross-section view of one embodiment of a stub pipe housing for preventing fluid from escaping a connection and directing fluid escaping a connection between a stub pipe and an external pipe to a cabinet; and 
         FIG. 4  depicts a perspective view of embodiments of a stub pipe housing relative to an exemplary HVAC cabinet, illustrating a stub pipe housing system capable of supporting external pipes relative to stub pipes to prevent bending of connections between the stub pipes and the external pipes and for directing fluid escaping from the connections to the cabinet. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure and its advantages are best understood by referring to  FIGS. 1 through 4  of the drawings, like numerals being used for like and corresponding parts of the various drawings. 
       FIG. 1  depicts an architectural diagram of an exemplary heating, ventilation, and air condition (“HVAC”) system, illustrating a refrigeration cycle. HVAC system  5  includes a compressor  110 , a condenser  120 , an expansion valve  130  and an evaporator  140 . Refrigerant flows through HVAC system  100  undergoing changes to its temperature, pressure, and phase. Compressor  110  receives heated gaseous refrigerant from evaporator  140  and compresses it such that the refrigerant changes phases to become a hot, high-pressure gas. The hot, high-pressure gas refrigerant is discharged from the compressor and received by condenser  120 . Fan  125  draws air flow across condenser  120 , which condenses the received hot, high-pressure gas into hot, high-pressure liquid. This hot, high-pressure liquid is expelled from condenser  120  to expansion valve  130 . Expansion valve  130  allows reduction of the pressure of the refrigerant, thereby producing a combination of refrigerant vapor and cold, low-pressure liquid refrigerant. The cold, low-pressure liquid refrigerant is then directed to evaporator  140  to be used to condition air of an enclosed space. For example, air received from a return duct (not illustrated) is blown over circuits  145  of evaporator  140  through which the cold, low-pressure liquid refrigerant is circulated. Due to heat-exchange principles, heat is transferred from the return air to circuits  145 , thereby cooling the air and warming the refrigerant in circuits  145 . The cooled air is then directed to the enclosed space and the superheated gaseous refrigerant is expelled to the compressor(s)  110 . 
     Although this disclosure describes and depicts HVAC system  5  including particular components, this disclosure recognizes that HVAC system  5  may include (or exclude) other components. Embodiments of HVAC system  5  are usable in commercial systems or residential systems, and can be part of a split system air conditioning system, a heat pump, or a refrigeration unit for example. 
     When connecting evaporator  140  to fluid lines in a refrigeration cycle, evaporator  140  is typically housed in a cabinet.  FIG. 2  depicts a perspective view of an exemplary evaporator cabinet in an HVAC system, illustrating the complexity of HVAC systems and the proximity of internal components to stub pipes. As depicted in  FIG. 2 , a typical evaporator cabinet  200  is configured to maximize the capacity of the system with a minimal volume, with stub pipes  10  extending from an evaporator  140 . To connect evaporator  140  to a fluid line, a technician typically brazes the connections between stub pipes extending from the cabinet and external pipes in the fluid lines. These brazed connections are reliable for preventing fluid leakage from the fluid lines. However, the distance that stub pipes  10  extend from cabinet  200  affects how easily the connections can be brazed. For example, if the stub pipes do not extend (or extend a negligible amount) from a back panel, brazing the connection could damage an expansion valve  130 , circuits  145 , electronic controls, and sensors that are typically positioned in cabinet  200  with minimal clearance relative to a back panel (not shown) and frame  220 . Furthermore, modifying the design of the cabinet to include the connections has drawbacks. For example, making the cabinet larger might require modifications to an environment in which the HVAC cabinet is to be installed, and if the stub pipes are located within the cabinet  200 , brazing connections becomes more difficult due to the limited space in the cabinet and the close proximity to the expansion valve  130 , circuits  145 , electronic controls, and sensors. Even a skilled technician will have more trouble getting a good brazed connection as access to the stub pipes decreases. 
     Accordingly, embodiments disclosed herein allow technicians to use existing skills for brazing reliable connections between stub pipes and external pipes as a solution for providing safe handling of refrigerants and other fluids. Embodiments can seal an external connection between a stub pipe and an external pipe and support the connection to prevent leakage and, in the event any fluid escapes the connection, these same embodiments can direct fluid to a cabinet for detection and mitigation. 
       FIG. 3  depicts a cross-section view of one embodiment of a stub pipe housing for sealing an external connection to prevent fluid leakage and directing any fluid that might leak from a connection between a stub pipe and an external pipe to a cabinet. As depicted in  FIG. 3 , a stub pipe housing  300  comprises end  310  configured for sealed contact with back panel or other external surface  221  of cabinet  200  and an inner surface  305  formed with a non-permeable material extending to end  330  adapted for sealed contact with the external pipe  20  at a distance beyond a connection  25  between a stub pipe  10  and the external pipe  20 . 
     In some embodiments, end  310  comprises a flange configured to surround any openings in cabinet  200 . In some embodiments, cabinet  200  comprises only a stub pipe opening  215  and end  310  is configured to surround stub pipe opening  215  such that all fluid escaping from a connection between an external pipe  20  and a stub pipe  10  is contained within volume  340  where it is directed through the stub pipe opening  215  into cabinet  200 . In other embodiments, cabinet  200  comprises perforations or other openings  216  and end  310  is configured to surround stub pipe opening  215  and openings  216  such that any fluid escaping the connection is routed through the stub pipe opening  215  or the other openings  216 . One or more of openings  215 ,  216  are formed to allow fluid flow toward a sensor for detecting fluid leaks or a fan or other system for dissipating fluid buildup or otherwise mitigating fluid leaks. 
     In some embodiments, stub pipe housing  300  is formed with non-permeable material for supporting a connection between an external pipe  20  and stub pipe  10 . In some of these embodiments, stub pipe housing  300  is formed with resilient material, wherein end  330  forms sealed contact with external pipe  20 . The resilient material determines the amount of support possible by the stub pipe housing  300 . Elastomeric materials are examples of a resilient material capable of sealed contact with external pipe  20  and capable of supporting the connection between external pipe  20  and stub pipe  10 . In other embodiments, stub pipe housing  300  is formed with rigid material and end  330  is formed with compliant material for sealed contact with external pipe  20 . Advantageously, stub pipe housing  300  configured to support the connection between external pipe  20  and stub pipe  10  reduces the likelihood that fluid escapes. 
     Stub pipe housing  300  is formed to contain any fluid escaping connection between external pipe  20  and a stub pipe  10  and direct the escaped fluid to the cabinet  200 . Embodiments of stub pipe housing  300  is formed with a uniform cross-section, graduated cross-section, or stepped cross-section. The size and cross-section can be selected based on the size of external pipe  20  or based on available clearance. For example, a pressurized line typically has a smaller diameter and may be better supported with a stub pipe housing with a more rigid material formed into a smaller cross-section, whereas a return line typically has a larger diameter and may be better supported with a stub pipe housing having a more resilient material but formed with a larger cross-section. In the event fluid does escape from the connection, sealed contact between external pipe  20  and end  330  ensures any fluid leakage is contained within volume  340  of stub pipe housing  300 , wherein stub pipe housing  300  directs fluid escaping the connection to flow through opening  215  and/or openings  216  into cabinet  200 . In some embodiments, end  330  comprises compliant or elastomeric material. 
     Embodiments of a system for preventing fluid escaping from any of multiple fluid lines are configured with a stub pipe housing for preventing fluid leakage from a pressurized line and a stub pipe housing for preventing fluid loss from a return or non-pressurized line.  FIG. 4  depicts a perspective view of one embodiment of a stub pipe housing system for use in a system such as an HVAC system, in which components can have a high pressure line and a low pressure line. The pressurized line is generally smaller in diameter but has a higher pressure and may have a thicker wall thickness to handle the increased pressure. Embodiments disclosed herein include systems with stub pipe housings capable of supporting external pipes relative to stub pipes for a pressurized line and a non-pressurized line. Each stub pipe housing  300 - 1 ,  300 - 2  is configured to prevent bending of a connection between the stub pipe and the external pipe and for directing fluid escaping from the connection to a cabinet. Furthermore, any material used to form stub pipe housings  300  may be selected to withstand low or high pressures and/or temperatures depending on the position in a refrigeration cycle. 
     As depicted in  FIG. 4 , stub pipes  10 - 1  and  10 - 2  extend from cabinet  200  for connecting to external pipes  20 - 1  and  20 - 2  respectively. To prevent fluid escaping either connection, each connection is protected by a stub pipe housing  300 - 1  or  300 - 2 . Generally, both stub pipe housings  300 - 1 ,  300 - 2  comprise ends  310 - 1 ,  310 - 2  for sealed contact with cabinet  200  and second ends  20 - 1  and  20 - 2  extending a distance beyond connections to external pipes  20 - 1  and  20 - 2 . However, external pipe  20 - 1  may be a high pressure line whereas external line  20 - 2  may be a low pressure line. Accordingly, stub pipe housing  300 - 1  is formed from a first material with first end  310 - 1  adapted for sealed contact with a cabinet, wherein stub pipe housing  300 - 1  extends a first distance to a second end  330 - 1 , and stub pipe housing  300 - 2  is formed from a second material with first end  310 - 2  adapted for sealed contact with the cabinet, wherein stub pipe housing  300 - 2  extends a first distance to a second end  330 - 2 . 
     Material used to form stub pipe housings  300  depend on the size of the system, fluid pressures in the fluid lines, fluid characteristics in the fluid lines, the environment in which the system is utilized. For example, material used to form a stub pipe housing to protect a connection on a fluid line outside a building may need to function in temperatures below freezing, withstand heat and sunlight, and other weather factors that could degrade material at a faster rate than material used indoors. Material used to form a stub pipe housing to protect a connection on a fluid line in a commercial or manufacturing environment may need to function in areas in which other chemicals are present, HVAC requirements are tightly controlled such that any HVAC system is operating at higher pressures, increased fluid flow rates or other demands on the HVAC system not present in a residential system. 
     Sealed contact between first end  310 - 1  or  310 - 2  and cabinet  200  may be achieved by direct contact between first end  310 - 1  or  310 - 2  and an external surface or opening or cabinet  200  or a gasket, seal, o-ring or other intermediate component may be interposed between first end  310 - 1  or  310 - 2  and an external surface or opening in cabinet  200  to ensure sealed contact. In some embodiments, first end  310 - 1  or  310 - 2  comprises a flange extending radially outward as a surface, wherein sealed contact between the stub pipe housing  300 - 1  or  300 - 2  comprises contact between the surface of the flange and the external surface of the cabinet, and hardware or an adhesive is used to ensure sealed contact. In other embodiments, first end  310 - 1  or  310 - 2  comprises a flange extending radially outward as an edge, wherein sealed contact between the stub pipe housing  300 - 1  or  300 - 2  and the cabinet comprises positioning a seal on the cabinet and seating the flange in the seal. 
     In some embodiments, supporting a high pressure fluid line comprises limiting the degree angle to which connection  45  can be bent. In various embodiments, stub pipe housing  300 - 1  is formed as a rigid member to prevent external pipe  20 - 1  bending relative to stub pipe  10 - 1 . In various embodiments, stub pipe housing  300 - 1  spans a longer distance across a connection to reduce the angle to which the connection may bend. In various embodiments, sealed contact between a first end  310 - 1  and cabinet  200  limits the angle to which the connection may bend. For example, embodiments with first end  310 - 1  formed with a large inner diameter and rigidly coupled to cabinet  200  prevents substantially any bending or rotation of the fluid line and prevents any bending of a connection. In other embodiments, first end  310 - 1  formed with a small inner diameter and a resilient seal allows some movement or rotation of the fluid line while still preventing bending of the connection. 
     For a high pressure fluid line, embodiments disclosed herein ensure fluid escaping a connection are directed to cabinet  200 . In some embodiments, second end  330 - 1  comprises a compliant seal that is clamped to external pipe  20  using hardware. In other embodiments, second end  330 - 1  comprises a compliant seal having an inner diameter slightly smaller than an outer diameter of external pipe  20 - 1 , wherein resistance between the compliant seal and external pipe  20  results in sealed contact between stub pipe housing  300 - 1  and external pipe  20 - 1 . In some embodiments, external pipe  20  comprises a circumferential groove or rib (not shown), wherein a compliant seal is adapted to seat in the groove or against the rib for sealed contact between stub pipe housing  300 - 1  and external pipe  20 - 1 . 
     A low pressure fluid line may have a larger diameter and less pressure and may also have a smaller wall thickness. In some embodiments, supporting a fluid line comprises stabilizing a connection between the external pipe  20  and stub pipe  10  and absorbing vibrations, forces or torques to which the connection may be exposed. In various embodiments, stub pipe housing  300 - 2  is formed as a resilient member to resist external pipe  20 - 1  moving or twisting relative to stub pipe  10 - 1  and absorb vibrations in the HVAC system. In various embodiments, sealed contact between a first end  310 - 2  and cabinet  200  limits the angle to which the connection external pipe  20  can move or twist relative to stub pipe  10 - 2 . For example, embodiments of stub-pipe housing  300 - 2  formed from a resilient material having a large wall thickness and rigidly coupled to cabinet  200  prevents substantially any bending or rotation of the fluid line near cabinet  200  and resists bending or twisting of external pipe  20 - 2  relative to stub pipe  10 - 2  but allows more freedom at second end  330 - 2 . In other embodiments, stub pipe housing  300 - 2  formed with a stepped or graduated cross-sectional profile and rigidly coupled to cabinet  200  prevents substantially any bending or rotation of the fluid line near cabinet  200  and resists bending or twisting of external pipe  20 - 2  relative to stub pipe  10 - 2  but allows more freedom at second end  330 - 2 . In some embodiments, stub pipe housing  300  is formed from an elastomeric material compound capable of providing support to a connection over a wide range of temperatures and adapted for non-permeability. 
     For a low pressure line, embodiments disclosed herein ensure fluid escaping a connection are directed to cabinet  200 . In some embodiments, second end  330 - 1  comprises a compliant seal that is clamped to external pipe  20  using hardware. In other embodiments, second end  330 - 1  comprises a compliant seal having an inner diameter slightly smaller than an outer diameter of external pipe  20 - 1 , wherein resistance between the compliant seal and external pipe  20  results in sealed contact between stub pipe housing  300 - 1  and external pipe  20 - 1 . In some embodiments, external pipe  20  comprises a circumferential groove or rib (not shown), wherein a compliant seal is adapted to seat in the groove or against the rib for sealed contact between stub pipe housing  300 - 1  and external pipe  20 - 1 . An advantage to embodiments such as depicted in  FIG. 4  include the ability to customize each stub pipe housing  300 - 1 ,  300 - 2  for a particular application. If a stub pipe housing  300 - 1 ,  300 - 2  has an associated sensor for detecting the presence of fluid, an advantage is the ability to determine if fluid is escaping from a connection or from some component in the cabinet, or determine from which connection fluid is escaping in embodiments with multiple sensors. 
     In various embodiments, portions of stub pipe housing  300 - 1  and  300 - 2  are integrated into a single housing  300  (not shown). For example, in some embodiments, stub pipe housing  300  comprises a first end  310  adapted for sealed contact with an external surface of cabinet  200  and having an inner diameter or shape to accommodate both stub pipe openings, wherein any fluid escaping a connection is directed into cabinet  200 . In various embodiments, stub pipe housing  300  comprises separate second ends  330 - 1 ,  330 - 2  to accommodate fluid lines of different diameters. Advantages to this design may include the ability to direct fluid escaping from either connection to a single point for detection and the additional support each fluid line can provide for supporting another fluid line. 
     Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. For example, refrigeration system may include any suitable number of compressors, condensers, condenser fans, evaporators, valves, sensors, controllers, and so on, as performance demands dictate. One skilled in the art will also understand that refrigeration system  100  can include other components that are not illustrated but are typically included with refrigeration systems. Additionally, operations of the systems and apparatuses may be performed using any suitable logic comprising software, hardware, and/or other logic. As used in this document, “each” refers to each member of a set or each member of a subset of a set. 
     Modifications, additions, or omissions may be made to the methods described herein without departing from the scope of the disclosure. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. 
     Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the spirit and scope of this disclosure.