Patent Description:
Heating, ventilation, and/or air conditioning (HVAC) systems for residential or commercial buildings typically include an outdoor unit and an indoor unit. The indoor unit contains an indoor heat exchanger, which absorbs heat from the air being passed through the system using a refrigerant when the system is operating in cooling mode. The outdoor unit contains an outdoor heat exchanger, which cools and condenses the gaseous refrigerant when the system is operating in cooling mode. This refrigerant, historically, has been provided as a fluid with a high GWP value such as R134A or R410A. Although these refrigerants are effective coolants, the effect they can have on the environment has led to the institution of requirements that new refrigerants, which have moderate-to-low GWP values, be employed instead.

Moderate-to-low GWP refrigerants can be mildly flammable or flammable, (i.e. A2L and/or A3 refrigerants), however, and thus their use in HVAC systems can present risks that needs to be addressed. In particular, to the extent that refrigerant leaks are possible in HVAC systems, it may be desirable to both promptly detect any leak and/or separate any leak from any potential ignition sources. Potential ignition sources may include any component with an open electrical circuit that has enough energy to potentially ignite the refrigerant. One component of conventional HVAC systems that has a traditionally open electrical circuit is a contactor. These contactors are typically housed within the control box of an outdoor HVAC unit.

Potential solutions currently being considered to mitigate the potential ignition of A2L and/or A3 refrigerants include either (i) redesigning the ignition components (e.g., the contactors), and/or (ii) completely sealing the areas with ignition components (e.g., the control box). However, each of these potential solutions may significantly increase the cost of the unit, and may not aid in the detection of refrigerant leaks.

<CIT> discloses a system comprising a baffle connected to a coil of a heat exchanger assembly, wherein the baffle captures any liquid refrigerant that leaks from the coil and directs said refrigerant toward a drain pan.

Accordingly, there remains a need to for a heating, ventilation, and/or air conditioning (HVAC) system with a more easily implementable solution that mitigates the potential ignition of A2L and/or A3 refrigerants while also aiding in the detection of refrigerant leaks.

According to a first aspect of the invention, a heating, ventilation, and/or air conditioning (HVAC) system including a heat exchanger and a baffle is provided. The heat exchanger can be used for transferring heat between a refrigerant and a fluid medium. The heat exchanger includes a lateral side where a bend in the heat exchanger is located. The baffle may be disposed vertically adjacent to the lateral side of the heat exchanger, vertically being defined from a lower surface of the HVAC system. The baffle comprises a fishbone configuration or a helical configuration and is configured to direct at least a portion of a refrigerant leak.

Optionally, the baffle is disposed within at least one of an outdoor unit and an indoor unit.

Optionally, the baffle is disposed less than one (<NUM>) inch (<NUM>) from the lateral side of the heat exchanger.

Optionally, at least a portion of the refrigerant leak is directed downward by the baffle toward a nondispersive infrared sensor.

Optionally, the nondispersive infrared sensor is disposed adjacent to a distal end of the baffle.

Optionally, the refrigerant includes at least one of an A2L refrigerant and an A3 refrigerant.

Optionally, the A2L refrigerant is R454B.

Optionally, the HVAC system further includes a control box disposed within at least one of the outdoor unit and the indoor unit, the control box including at least one electrical component for controlling the supply of an electrical power to the HVAC system.

Optionally, the baffle directs substantially all of the refrigerant leak away from the control box.

According to another aspect of the invention, a method for controlling the flow of a refrigerant leak of a heating, ventilation, and/or air conditioning (HVAC) system is provided. The method provides for the operating of a pump to circulate a refrigerant between an indoor heat exchanger and an outdoor heat exchanger, a baffle disposed vertically adjacent to a lateral side of at least one of: the indoor heat exchanger and the outdoor heat exchanger, the lateral side being defined where a bend in the heat exchanger is located, vertically being defined from a lower surface of the HVAC system. The method also provides for the directing of at least a portion of a refrigerant leak, with the baffle, downward toward a nondispersive infrared sensor, the baffle comprising a fishbone configuration or a helical configuration.

Optionally, the method further includes the triggering of a response with the nondispersive infrared sensor when the nondispersive infrared sensor detects at least a <NUM>% lower flammability limit.

Optionally, the at least <NUM>% lower flammability limit is reached by a leak of at least one of an A2L refrigerant and an A3 refrigerant.

Optionally, the nondispersive infrared sensor triggers the response within ten seconds of being exposed to <NUM>% lower flammability limit.

Optionally, the response includes at least one of: an alarm signal, stopping operation of the pump, opening a damper, and operating an indoor fan of the HVAC system.

The following descriptions of exemplary embodiments are by way of example only and should not be considered limiting in any way.

As will be described below, a heating, ventilation, and/or air conditioning (HVAC) system including a baffle disposed vertically adj acent to a lateral side of a heat exchanger, and a method of controlling the flow of a refrigerant leak using the baffle are provided. The baffle may direct a refrigerant leak to a refrigerant detection assembly and/or away from a control box. Directing the refrigerant leak toward the refrigerant detection assembly may enable the refrigerant detection assembly to more quickly detect a refrigerant leak. The refrigerant detection assembly may utilize a nondispersive infrared (NDIR) sensor to detect refrigerant leaks. Directing the refrigerant leak away from the control box may help mitigate the potential ignition of the refrigerant. This may be because the control box may include at least one electrical component (e.g., a contactor), which may have an open electrical circuit that has enough energy to potentially ignite the refrigerant. The use of this baffle to control the flow of a refrigerant leak may be especially useful when a flammable refrigerant, such as an A2L refrigerant (e.g., R454B) and/or an A3 refrigerant, is used within the HVAC system.

The classification of refrigerant is based upon American Society of Heating, Refrigerating and Air-Conditioning (ASHRAE) Standard <NUM>. The standard evaluates each refrigerant's flammability and toxicity and gives it a class referenced as a letter and number combination. The letter refers to the refrigerants toxicity, and is based on the particular refrigerant's occupational exposure limit (OEL). An "A" is given to refrigerants with a <NUM> ppm or greater OEL. A "B" is given to refrigerants with less than <NUM> ppm OEL. The number adjacent to the letter refers to the refrigerants flammability, and is based on the burning velocity (BV), heat of combustion (HOC), and lower flammability limits (LFL) of the particular refrigerant. A flammability of "<NUM>" is the lowest, with a "<NUM>" being the highest. Recently the second class was broken into "<NUM>" and "<NUM>". A rating of "<NUM>" indicates that while the refrigerant is still considered flammable, its flammability is much lower than that of class <NUM> or <NUM>. It should be appreciated that the use of the baffle to direct refrigerant leaks may be useful in the detection and/or ignition mitigation of any flammable refrigerant (e.g., A2L, A2, and/or A3 refrigerants). Depending on the classification of the refrigerant however different mitigation strategies may be necessitated (e.g., additional measures may be needed for A2 and/or A3 refrigerants) due, at least in part, to the particular lower flammability limit (LFL) of the refrigerant being utilized.

A lower flammability limit (LFL) of a refrigerant is the minimum concentration limit that is required for the refrigerant to become potentially combustible. For example, R-<NUM>, which is an A2L refrigerant, has a LFL of <NUM>%. A <NUM>% LFL value is one quarter of the value of the LFL. For example, R-<NUM> has a <NUM>% LFL value of <NUM>%. For illustrative purposes, if the R-<NUM> were used as the refrigerant in the HVAC system, the refrigerant detection assembly may be configured to trigger a response when the refrigerant detection assembly detects at least <NUM>% of R-<NUM> in the sample. In certain instances, the refrigerant detection assembly may be capable of triggering a response within ten seconds of the refrigerant detection assembly being exposed to <NUM>% LFL. For example, if using R-<NUM> as the refrigerant, the refrigerant detection assembly may be capable of triggering a response within ten seconds of being exposed to <NUM>% R-<NUM>.

With reference now to the Figures, a heating, ventilation, and/or air conditioning (HVAC) system <NUM> is schematically shown in <FIG>. The HVAC system <NUM> may be provided for use within a building, such as a residential or commercial building, and may be configured as a ductless or ducted system. For purposes of clarity and brevity, however, the following description will relate to the exemplary use of the HVAC system <NUM> as a ducted system. The HVAC system <NUM> may include an indoor unit <NUM> and an outdoor unit <NUM>. When operating in cooling mode, the indoor heat exchanger <NUM> absorbs heat from the air being passed through the HVAC system <NUM>. The cooled air is then circulated into the building by way of the air ducts. The outdoor unit <NUM>, in addition to including an outdoor heat exchanger <NUM>, may also include a fan and a pump <NUM>. When operating in cooling mode, the outdoor heat exchanger <NUM>, in combination with the fan, operates to absorb heat from the refrigerant being passed through the outdoor unit <NUM>. The pump in the outdoor unit <NUM> pumps the refrigerant in a cyclical manner through the HVAC system <NUM>. This refrigerant may, in rare instances, leak into the HVAC system <NUM> (e.g., through one or more crack in a heat exchanger <NUM>, <NUM>). When utilizing a flammable refrigerant in the HVAC system <NUM>, a leak of refrigerant could lead to undesirable consequences due to the flammable nature of the refrigerant.

As described above, both the outdoor heat exchanger <NUM> and the indoor heat exchanger <NUM> may be capable of transferring heat between a refrigerant and a fluid medium (e.g., transferring heat to or from air, water, etc.). To circulate air through the indoor unit <NUM> (e.g., to transfer heat between the air and the refrigerant in the indoor heat exchanger <NUM>), the indoor unit <NUM> may include a fan <NUM>. To control the supply of power (e.g., to the pump <NUM>), the outdoor unit <NUM> may include an electrical component <NUM>. As mentioned above, the electrical component <NUM> may contain enough energy to potentially ignite a flammable refrigerant (e.g., an A2L and/or A3 refrigerant). This may be especially possible when the electrical component <NUM> makes or breaks the circuit. For example, when the electrical component <NUM> either connects or disconnects power from the power grid to one or more load devices, such as, a pump <NUM>. In certain instances, the electrical component <NUM> is housed within a control box <NUM>. It should be appreciated that the outdoor unit <NUM> and the indoor unit <NUM> each may respectively have a control box <NUM>, which may house at least one electrical component <NUM>. To mitigate the potential ignition of refrigerant in the event of a refrigerant leak, the HVAC system <NUM> may be designed in such a way that if a refrigerant leak occurs, the refrigerant is directed away from the electrical component <NUM> and/or the control box <NUM>. This directing of the refrigerant leak may be completed using a baffle <NUM> (shown in <FIG>). This baffle <NUM> may be disposed vertically adjacent to the indoor heat exchanger <NUM> and/or the outdoor heat exchanger <NUM>.

<FIG> depicts the baffle <NUM> disposed vertically adjacent to the lateral side <NUM> of the outdoor heat exchanger <NUM>. Vertically adjacent may be interpreted to mean that the baffle <NUM> is configured approximately perpendicular to the lower surface of the unit of which it is incorporated (e.g., the lower surface of the indoor unit <NUM> and/or lower surface of the outdoor unit <NUM>). Being approximately perpendicular may mean that the baffle <NUM> and the lower surface of the unit form an angle of approximately <NUM>° (e.g., +/- <NUM>°). It is envisioned that the baffle <NUM> may be disposed at any angle so long as the baffle <NUM> is capable of directing at least a portion of a refrigerant leak.

The lateral side <NUM> of the heat exchanger <NUM> is shown in <FIG>. The lateral side <NUM> of the heat exchanger <NUM> may be interpreted to mean the location at which the heat exchanger <NUM> terminates. For example, when the heat exchanger <NUM> is made of one or more coil(s), the heat exchanger <NUM> may terminate where the coil stops and/or forms a bend <NUM>. It being noted that both the indoor heat exchanger <NUM> and the outdoor heat exchanger <NUM> may include one or more lateral side(s) of which a baffle <NUM> may be disposed vertically adjacent to. In certain instances the baffle <NUM> is disposed less than one (<NUM>) inch (<NUM>) from the lateral side <NUM> of the heat exchanger <NUM> so as to be capable of directing at least a portion of a refrigerant leak. It should be appreciated that the baffle <NUM> may be placed farther than one (<NUM>) inch (<NUM>) from the lateral side <NUM> of the heat exchanger <NUM>. Placing the baffle <NUM> vertically adjacent to the lateral side <NUM> (e.g., where a bend <NUM> in a coil may be found) may increase the ability of the baffle <NUM> to direct a refrigerant leak, as leaks may be more likely to occur along the lateral side <NUM> of the heat exchanger <NUM>.

The placement of the baffle <NUM> vertically adjacent to the lateral side <NUM> of the heat exchanger <NUM> may enable the baffle <NUM> to direct at least a portion of a refrigerant leak downward (e.g., toward a refrigerant detection assembly <NUM>). The refrigerant detection assembly <NUM> may be disposed adjacent to a distal end <NUM> of the baffle <NUM>. The distal end <NUM> of the baffle <NUM> may be interpreted to be the end of the baffle <NUM> opposite of the proximal end <NUM> of the baffle <NUM>. In certain instances, the distal end <NUM> of the baffle <NUM> is located near the lower surface of the unit of which the baffle <NUM> is incorporated. In certain instances, the refrigerant detection assembly <NUM> may be disposed on the lower surface of the unit of which it is incorporated (e.g., the lower surface of the indoor unit <NUM> and/or lower surface of the outdoor unit <NUM>) and/or attached to the sheet metal of the unit of which it is incorporated (e.g., adjacent to the lateral side <NUM> of the heat exchanger <NUM>).

When refrigerant leaks from a heat exchanger <NUM>, the refrigerant exits the heat exchanger <NUM> (e.g., through a crack in the coil) at a high velocity (e.g., as a stream of liquid refrigerant) due to the refrigerant being under pressure. This pressure may be caused, at least in part, by the pump <NUM>. The baffle <NUM>, by being disposed vertically adjacent to the lateral side <NUM> of the heat exchanger <NUM>, may stop the stream of refrigerant from shooting into the control box <NUM> (e.g., where the electrical component <NUM> may be) by coming into contact with the refrigerant. In certain instances, the baffle <NUM> stops substantially all of the refrigerant leak (e.g., keeping substantially all the refrigerant leak from entering the control box <NUM>).

Once the refrigerant comes into contact with the baffle <NUM>, the refrigerant may be directed downward, as shown in <FIG> and <FIG>. In certain instances, the baffle <NUM> directs the refrigerant downward due, at least in part, to the shape of the baffle <NUM>. A first embodiment of a baffle <NUM> in a helical configuration is shown in <FIG>. The helical configuration may be any configuration that has a surface that extends around a central axis (e.g., in a screw-like or spiral manner). In certain instances, the refrigerant, once coming into contact with the baffle <NUM>, flows around the helical configuration downward toward a refrigerant detection assembly <NUM>. A second embodiment of a baffle <NUM> in a fishbone configuration is shown in <FIG>. The fishbone configuration may be any configuration that has a surface that causes a liquid to flow in a back and forth, downward manner. In certain instances, the fishbone configuration includes a series of holes and flaps to cause the refrigerant to flow in a back and forth, downward manner (e.g., from one flap to another all the way down the baffle <NUM>). To get the refrigerant to flow from one flap to another, each flap may have an opposite slanting orientation relative to the above/below flap. In certain instances, the refrigerant, once coming into contact with the baffle <NUM>, flows down the fishbone configuration toward a refrigerant detection assembly <NUM>.

The refrigerant detection assembly <NUM> may include a nondispersive infrared (NDIR) sensor and a controller operatively connected to the nondispersive infrared sensor (e.g., using one or more wireless and/or wired connection) to receive output signals from the NDIR sensor and determine whether a response should be triggered. The controller may be configured to trigger a response when the refrigerant detection assembly <NUM> detects at least <NUM>% lower flammability limit (LFL). In instances where the refrigerant detection assembly <NUM> detects a leak (ex. when the refrigerant detection assembly <NUM> detects at least <NUM>% LFL) in the HVAC system <NUM>, the response triggered by the controller may include at least one of: an alarm signal, stopping operation of the pump <NUM>, opening a damper <NUM> (as shown in <FIG>), and operating an indoor fan <NUM> of the HVAC system <NUM>. The response may encourage the dilution of refrigerant in the building or HVAC system <NUM> by directing (e.g., using the damper <NUM>) the air from the HVAC system <NUM> outside the building. In certain instances, the response includes both opening the damper <NUM> and operating the indoor fan <NUM> of the HVAC system <NUM> to direct the air from the HVAC system <NUM> outside the building. By utilizing a damper <NUM>, the HVAC system <NUM> may be capable of redirecting air outside the building when potentially hazardous conditions are present.

As described above, the configuration of the HVAC system <NUM> may allow for refrigerant leaks to be controlled in a manner that both mitigates the potential ignition of the refrigerant (e.g., by directing leaking refrigerant away from the control box <NUM>, which may contain one or more electrical component <NUM>) while also aiding in the detection of refrigerant leaks (e.g., by directing leaking refrigerant toward a refrigerant detection assembly <NUM>).

The method <NUM> for controlling the flow of a refrigerant leak is illustrated in <FIG>. This method <NUM> may be done, for example, using the exemplary HVAC system <NUM>, as shown in <FIG>, which includes a baffle <NUM> disposed vertically adjacent to a lateral side <NUM> of a heat exchanger <NUM>. As shown in <FIG>, the method <NUM> includes step <NUM> of operating a pump <NUM> to circulate a refrigerant between an indoor heat exchanger <NUM> and an outdoor heat exchanger <NUM>, a baffle <NUM> disposed vertically adj acent to at least one of the indoor heat exchanger <NUM> and the outdoor heat exchanger <NUM>. The method <NUM> further includes step <NUM> of directing at least a portion of a refrigerant leak, with the baffle <NUM>, downward toward a refrigerant detection assembly <NUM>. The refrigerant detection assembly <NUM> may include a nondispersive infrared (NDIR) sensor capable of detecting refrigerant (e.g., an A2L refrigerant, such as R454B, and/or an A3 refrigerant). The method <NUM> may further include step <NUM> for triggering a response (e.g., with a controller of the refrigerant detection assembly <NUM>) when the refrigerant detection assembly <NUM> detects at least a <NUM>% lower flammability limit. The <NUM>% lower flammability limit may be reached by a leak of at least one A2L and/or A3 refrigerant. In certain instances, the refrigerant detection assembly <NUM> triggers the response within ten (<NUM>) seconds of being exposed to <NUM>% lower flammability limit. As described above, the response triggered by the refrigerant detection assembly <NUM> may include at least one of an alarm signal, stopping operation of the pump <NUM>, opening a damper <NUM>, and operating an indoor fan <NUM> of the HVAC system <NUM>.

Claim 1:
A heating, ventilation, and/or air conditioning (HVAC) system (<NUM>) comprising:
a heat exchanger (<NUM>, <NUM>) for transferring heat between a refrigerant and a fluid medium, the heat exchanger comprising a lateral side (<NUM>) where a bend in the heat exchanger is located; and
a baffle (<NUM>) disposed vertically adjacent to the lateral side of the heat exchanger,
vertically being defined from a lower surface of the HVAC system, the HVAC system characterized by the baffle
comprising a fishbone configuration or a helical configuration configured to direct at least a portion of a refrigerant leak.