Patent Application
20220307740
The presently disclosed embodiments generally relate to heating, ventilation, air conditioning, and refrigeration (HVAC) systems, and more particularly, to a system and method for mitigating risk from a leaked refrigerant, wherein the indoor section of a unit that could leak into the occupied space.
Refrigeration systems, as used in HVAC applications, utilize a closed loop refrigerant circuit to condition air inside an interior space of a building. Over the years, the HVAC industry has been using refrigerants with high Global Warning Impact (GWP) levels; however, the use of these refrigerants are currently being phased out by environmental regulations like the Kigali agreement due to their inherent high Global Warming Impact (GWP).
New refrigerants have been developed to comply with environmental regulations relating to global warming potential (GWP). In order to comply with the proposed GWP regulations, hydrofluorocarbon (HFC) and Hydrofluro-Olefins (HFO) that are mildly flammable are being developed and are being considered for use in lower GWP refrigerant HVAC systems.
As with any system, there is a potential fir the low flammability refrigerants used in HVAC applications to leak and migrate to undesirable areas in the vicinity of the HVAC system and building. When the flammable refrigerants, in the presence of air or another oxidizer, are exposed to an ignition source, the potential for a combustion event may be minimized if the mixture is kept below a lower flammability limit (LFL).
Disclosed is a heat exchanger assembly including: a coil; one baffle connected to a first end of the coil, the one baffle being configured to capture a liquid refrigerant that has leaked from the coil, the one baffle being configured to direct the liquid refrigerant toward a first end of a drain pan.
In addition to one or more of the above disclosed aspects or as an alternate the heat exchange assembly includes another baffle connected to a second end of the coil, the other baffle being configured to direct the liquid refrigerant toward a second end of the drain pan.
In addition to one or more of the above disclosed aspects or as an alternate the first end of the coil includes a coil header and the second end of the coil includes a hairpin.
In addition to one or more of the above disclosed aspects or as an alternate the heat exchange assembly includes a first baffle at the first end of the coil and a second baffle at the second end of the coil, wherein the one baffle is a third baffle and the another baffle is a fourth baffle.
In addition to one or more of the above disclosed aspects or as an alternate the first baffle is connected to a top side of the coil at the first side of the coil, and the third baffle is connected to a bottom side of the coil at the first side of the coil; and the second baffle is connected to the top side of the coil at the second side of the coil, and the fourth baffle is connected to the bottom side of the coil at the second side of the coil.
In addition to one or more of the above disclosed aspects or as an alternate in an end-to-end direction for the coil, the third baffle has a span that is less than a span of the baffle, thereby exposing at least a portion of the coil header.
In addition to one or more of the above disclosed aspects or as an alternate in the end-to-end direction for the coil, the fourth baffle has a span that is the same as or greater than a span of the second baffle.
In addition to one or more of the above disclosed aspects or as an alternate one or both of the third baffle and the fourth baffle is a flat plate.
In addition to one or more of the above disclosed aspects or as an alternate the heat exchange assembly includes a drain pan, the coil being seated in the drain pan, the drain pan configured to receive the liquid refrigerant from the third baffle and the fourth baffle when the liquid refrigerant has leaked from the first end or the second end of the coil and is captured by the third baffle or the fourth baffle.
In addition to one or more of the above disclosed aspects or as an alternate floor of the drain pan is skewed at an angle so that the first end of the drain pan is lower than the second end of the drain pan, whereby when liquid refrigerant has drained into the second end of the drain pan, the liquid refrigerant is directed to the first end of the drain pan.
In addition to one or more of the above disclosed aspects or as an alternate the heat exchange assembly includes a sensor operationally connected to the first end of the coil, the sensor configured for sensing the liquid refrigerant.
In addition to one or more of the above disclosed aspects or as an alternate the sensor is disposed at the header between the third baffle and the first baffle, whereby the sensor is configured to sense liquid refrigerant captured at the third baffle.
In addition to one or more of the above disclosed aspects or as an alternate the sensor is disposed proximate the first end of the drain pan, whereby the sensor is configured to sense liquid refrigerant captured by the fourth baffle that has been received at the second end of the drain pan and directed within the drain pan to the first end of the drain pan.
Further disclosed is an indoor HVAC assembly including: a housing, and a heat exchanger assembly having one or more of the above disclosed aspects.
In addition to one or more of the above disclosed aspects or as an alternate the assembly includes a fan disposed with the housing, the fan configured to provide an airflow across the heat exchanger assembly.
In addition to one or more of the above disclosed aspects or as an alternate the assembly includes a system controller that communicates with the sensor, the system controller configured to: receive a signal from the sensor, wherein the signal is indicative of a refrigerant leak; and operate the fan responsive to receiving the signal.
In addition to one or more of the above disclosed aspects or as an alternate the system controller is configured to deactivate a compressor responsive to receiving the signal.
Further disclosed is a method of operating an air conditioning system, including: receiving a signal from a sensor disposed on a heat exchanger assembly, the signal being indicative of a refrigerant leak, wherein the sensor is disposed adjacent to one baffle at a fan coil header of a coil, the one baffle being configured to capture refrigerant that has leaked from the coil, the one baffle being configured to direct the refrigerant toward a first end of a drain pan; and activate the fan responsive to receiving the signal.
In addition to one or more of the above disclosed aspects or as an alternate the method includes deactivating a compressor responsive to receiving the signal.
In addition to one or more of the above disclosed aspects or as an alternate the heat exchanger assembly includes another baffle connected to a second end of the coil, the other baffle being configured to direct the refrigerant toward a second end of the drain pan.
The embodiments and other features, advantages and disclosures contained herein, and the manner of attaining them, will become apparent and the present disclosure will be better understood by reference to the following description of various exemplary embodiments of the present disclosure taken in conjunction with the accompanying drawings, wherein:
For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of this disclosure is thereby intended.
The indoor HVAC assembly 30 includes an indoor heat exchanger (coil) 40, a blower 45, and evaporator drain lines 70. The indoor heat exchanger 40 may be formed from a microchannel heat exchanger or a round tube plate fin heat exchanger and may be configured as a slab coil as shown, an A-coil configuration or other configuration. The indoor heat exchanger 40 is disposed over a drain pan 50, which may also he referred to as a condensate receptor, and configured to collect condensate from the indoor heat exchanger 40.
With the requirements to move to lower GWP refrigerants it is likely that mildly flammable refrigerants, referred to in the art as “A2L refrigerants” and defined in standards like ASHRAE 34, will be used. New safety standard and building code that have been developed for the use of A2L refrigerants require utilizing a refrigerant sensor that should respond to low as well as high leaks. A2L refrigerants as well as most refrigerants are heavier than air and tend to drop in the unit, but also as the refrigerant leaks it can induce airflow as well as change the average density of the air refrigerant mixture and cause airflow and the refrigerant not to concentrate impacting the ability to detect low leak refrigerant leaks. A structure is needed to prevent such refrigerants from being drawn out of the area where the sensor is located due the above mentioned induced airflow and migration of the heavier than air refrigerant.
Turning to
The heat exchanger assembly 100 includes a coil 110. The coil 110 may be round tube plate fin or microchannel coil. It is to be appreciated that benefits of the disclosed embodiments may be applied to all types of heat exchangers. The coil 110 includes a first end 120a and a second end 120b. Both ends are illustrated in
A first baffle 125a is attached to a bottom side 145 of the coil 110 at the first end 120a of the coil 110. A second baffle 125b is attached to the bottom side 145 the coil 110 at the second end 120b of the coil 110. A drain pan 130 is disposed below the coil 110. It will be appreciated that the drain pain 130 may be positioned in different locations based on the orientation of the indoor HVAC assembly 104, The drain pan 130 includes a first end 140a and a second end 140b extending between the first end 120a and the second end 120b of the coil 110. A floor 148 of the drain pan 130 is skewed at an angle. Thus the first end 140a of the drain pan 130 is lower than the second end 140b of the drain pan 130. From this, when fluid has drained into the other end 140b of the drain pan 130, the fluid is directed to the first end 140a of the drain pan 130.
According to an embodiment the assembly 100 may include a third baffle 150a and a fourth baffle 150b (alternatively referred one baffle and another baffle). The third baffle 150a may be connected to a top side 155 of the coil 110 at the first end 120a, of the fan coil 110. The third baffle 150a may be connected to structure of the coil 110, including coil tube-sheets or other typical fan coil structure. The connection maybe a first clip 160a.
According to an embodiment a sensor 170 is operationally connected to the first end 120a of the coil 110. The sensor 170 configured for sensing vapor refrigerant. The sensor 170 is disposed between the third baffle 150a and the first baffle 125a at the header 122.
The third baffle 150a is configured to focus or concentrate at the sensor 170 any refrigerant that has leaked in the form of vapor from the fan coil 110, which may otherwise be carried away by action of the fan 106 or natural convection.
The sensor 170 is effective when the indoor HVAC assembly 104, including the fan 106, is off as once the fan 106 is energized the air dilutes the refrigerant. If the indoor HVAC assembly 104 is off and there is a leak the sensor 170 will detect the leak. The baffles focus the leaking refrigerant to the area of the sensor 170 and increase the sensitivity. Once the sensor 170 has detected the leak the fan 106 is energized and the compressor, e.g., in the outdoor HVAC assembly 20 is prevented from running to purge and dilute the refrigerant. The baffles help concentrate the leaking refrigerant and accelerate and improve the detection of leaking refrigerant.
The fourth baffle 150 may be connected to the top side 155 of the coil 110 at the second end 120b of the coil 110. The fourth baffle 150b may be connected to structure of the coil 110, including coil tube-sheets or other typical fan coil structure. The connection may be by a second clip 160b. The fourth baffle 150b is configured to capture refrigerant that has leaked from the coil 110 and otherwise may be carried away by action of the fan 106 or natural convection. Once captured, the fourth baffle 150b is configured to direct the fluid downwardly, toward the second end 140b of the drain pan 130. In addition, fluid not directed downwardly by the fourth baffle 150b will flow downwardly by gravity into the second end 140b of the drain pan 130. From there, due to the skewed angle of the floor 148 of the drain pan 130, the fluid that drains into the second end 140b of the drain pan 130 will be directed to the first end 140a of the drain pan 130.
According to an embodiment, in end-to-end direction D1 for the fan coil 110, the third baffle 150a has a span S1 that is less than a span S2 of the first baffle 125a. This configuration exposes at least a portion of the fan coil header 122 in the end-to-end direction D1 the housing 102 that is exposed to the fan 106 for cooling purposes, e.g., to receive a natural or forced cooling airflow.
In the end-to-end direction D1 for the coil 110, the fourth baffle 150b has a span S3 that is the same as or greater than a span (not labeled) of the hairpin 124. This enables capturing a relative maximum amount of fluid that may be leaking from the second end of the fan coil 110. Due to the sizing of the second baffle 125b and the fourth baffle 150b, the hairpin side is fully enclosed so that refrigerant that leaks will fall down into the drain pain and run the along the hairpin side. With the partial width of the third baffle 150a relative to the first baffle 125a when the fan is running it will slowly vent the area. In addition, there is some leakage thru the first and second baffles 125a, 125b and there is a pressure drop thru the coil 110a, so some air will bypass the coil thru these baffles.
According to an embodiment, one or both of the third baffle 150a and the fourth baffle 150b may be a flat plate. The one or both of the third baffle 150a and the fourth baffle 150b may be plastic.
The sensor 170 may be disposed proximate the first end 140a of the drain pan 130. From this configuration the sensor 170 is configured to sense fluid captured by the fourth baffle 150b that has been received at the second end 140b of the drain pan 130 and directed within the drain pan 130 to the first end 140a of the drain pan 130.
A system controller 180 illustrated schematically is provided for the air conditioning system 10. The system controller 180 may communicate with the sensor 170. The system controller 180 may be configured to receive a signal from the sensor 170 when the sensor 170 senses a fluid leak. The system controller 180 may he configured to shut-off the system 10 responsive to receiving the signal. This would minimize or prevent further fluid leakage.
As shown in
The above disclosed embodiments enable leaking refrigerant to concentrate relatively quickly, improving a response time of the sensor 170.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.
Those of skill in the art will appreciate that various example embodiments are shown and described herein, each having certain features in the particular embodiments, but the present disclosure is not thus limited. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions, combinations, sub-combinations, or equivalent arrangements not heretofore described, but which are commensurate with the scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
This application claims the benefit of U.S. Application Ser. No. 62/898,818, filed on Sep. 11, 2019, which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2020/050035 | 9/10/2020 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62898818 | Sep 2019 | US |
