Patent Publication Number: US-2023160588-A1

Title: System and method for identifying clogged evaporator coil

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 63/282,277 filed Nov. 23, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Embodiments of the present disclosure relate to the art of air conditioning systems, and more particularly, to the condition of a heat exchanger of an air conditioning system. 
     Most air conditioning systems typically include one or more filters operable to capture dust, dirt, debris, and other particles within the air flow of the system. However, these filters are not able to trap all of the particulate matters within the air flow. As a result, over time, this particulate matter can accumulate on the exterior of the heat exchanger, such as the fins thereof. Because this particulate matter makes the heat exchanger less efficient in absorbing heat from the air, the remainder of the air conditioning system must compensate by running at a high power and consuming more energy. 
     BRIEF DESCRIPTION 
     According to an embodiment, a method for evaluating a heat exchanger of an air conditioning system includes measuring a pH level of a condensate of the heat exchanger and determining a condition of the heat exchanger in response to the pH level. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments comprising operating an indicator in response to the pH level to indicate a need for service. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments the indicator is associated with a component of the air conditioning system that is visible by a user. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments the component is a thermostat. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments the indicator is associated with a component of the air conditioning system that is visible by a service man. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments measuring the pH level of the condensate of the heat exchanger is performed automatically by a pH sensor. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments comprising comparing the pH level to a first threshold and in response to determining that the pH level is less than the first threshold, comparing the pH level to a second threshold. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments in response to determining that the pH level is less than or equal to the second threshold, communicating with a remote system a need for immediate service. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments in response to determining that the pH level is between the first threshold and the second threshold, estimating a date by which service will be required. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments measuring the pH level of the condensate of the heat exchanger is performed manually. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments measuring the pH level of the condensate is performed using one of a pH test strip, a pH meter, and a colorimeter. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments determining the condition of the heat exchanger in response to the pH level further comprises comparing the pH level to a correlated table. 
     According to an embodiment, an air conditioning system includes a heat exchanger, a pH sensor operable to monitor a pH level of a condensate from the heat exchanger, and a controller configured to receive the pH level of the condensate from the pH sensor and compare the pH level to at least one threshold to determine a condition of the heat exchanger. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments comprising a condensate drain pan disposed vertically beneath the heat exchanger. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments the pH sensor is arranged within the condensate drain pan. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments the controller is further configured to operating an indicator in response to the pH level to indicate a need for service. 
     In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments the controller is further configured to communicate a need for immediate maintenance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG.  1    is a front view of an example of a heat exchanger of an air conditioning system; 
         FIG.  2    is a perspective view of a portion of an air conditioning system including a heat exchanger according to an embodiment; 
         FIG.  3    is a perspective view of an air conditioning system including a heat exchanger according to an embodiment; 
         FIG.  4    is a detailed perspective view of a heat exchanger and a condensate drain pan according to an embodiment; and 
         FIG.  5    is a schematic diagram of a control system of an air conditioning system according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     With reference now to  FIG.  1   , an example of a portion of an air conditioning system  20  is illustrated. As used herein, the term “air conditioning system” is intended to include a heating, ventilation and air conditioning (HVAC) system and/or a refrigeration system including both single unit and split package systems. As shown, the portion of the air conditioning system  20  includes a heat exchanger  22  having at least one heat exchanger coil  24 . In an embodiment, the heat exchanger  22  may be configured as an evaporator within the air conditioning system  20 . It should be understood that embodiments where the heat exchanger is configured as a condenser are also contemplated herein. 
     In the illustrated, non-limiting embodiment, the heat exchanger  22  includes a plurality of heat exchanger coils  24  configured as a V-coil. However, it should be understood that a heat exchanger  22  having any number of coils  24 , such as a single coil, or more than two coils for example, is within the scope of the disclosure. Further, in embodiments having multiple coils  24 , it should be understood that coils  24  configured in an A-shape (see  FIG.  2   ), a W-shape, an M-shape, or another suitable shape are also contemplated herein. The plurality of coils  24 , may be fluidly coupled to one another, or alternatively, may be separate from one another. 
     The heat exchanger  22  may be any suitable type of heat exchanger configured to transfer heat between a refrigerant and air or another medium. For example, the heat exchanger  22  may include one or more coils of thermally conductive material, such as copper, aluminum, alloys thereof, or combinations thereof. In other embodiments, the heat exchanger  22  may be a shell-and tube heat exchanger, a printed circuit heat exchanger, a plate-fin heat exchanger, a microchannel heat exchanger, or any combination thereof. 
     A movement mechanism  26 , such as a fan or blower for example, is configured to move a cooling medium, such as a flow of air A for example, across the one or more coils  24  of the heat exchanger  22 . Although the movement mechanism  26  is illustrated as being disposed vertically above the heat exchanger  22 , and therefore in a draw-through configuration, it should be understood that embodiments where the movement mechanism  26  is positioned in a blow-through configuration, such as a blower  26  disposed vertically beneath a furnace  28  operably coupled to the heat exchanger  22  (see  FIG.  2   ) for example, are also within the scope of the disclosure. Although a residential air conditioning system  20  is illustrated in  FIG.  2   , it should be understood that the heat exchanger illustrated and described herein may also be used in a commercial air conditioning system, such as shown in  FIG.  3    for example. 
     With continued reference to  FIGS.  1 - 3   , and further reference to  FIG.  4   , disposed vertically beneath the heat exchanger  22  is a condensate drain pan  30 . The drain pan  30  is configured to capture or collect condensation that accumulates on and/or drips from the one or more heat exchanger coils  24  of the heat exchanger  22 . One or more conduits or channels  32  fluidly coupled to or formed in the drain pan  30  are configured to direct the condensate collected within the drain pan  30  outside of the air conditioning system  20  or to another component within the air conditioning system  20 . 
     With continued operation of the air conditioning system  20 , dirt, debris, and other particles may collect on the exterior surface of the heat exchanger  22 , such as between the fins of the or more heat exchanger coils  24 , thereby blocking, at least partially, the flow path through or across the heat exchanger  22 . As this particulate matter accumulates and clogs the flow path, the heat transfer between the refrigerant within the heat exchanger  22  and the air A is hindered, thereby lowering the efficiency of the air conditioning system  20 . In instances where no or minimal particulate matter is present on the heat exchanger  22 , the condensate that falls from the heat exchanger  22  to the drain pan  30  is primarily water having a generally neutral pH level. However, as the particulate matter accumulates on the heat exchanger  22 , the condensate that drips from the heat exchanger  22  to the drain pan  30  is a mixture of water and the particulate matter. As a result, the pH level of the condensate within the drain pan  30  will change due to the presence of the particulate matter therein. 
     With reference now to  FIG.  5   , the air conditioning system  20  includes a controller  40  having one or more of a microprocessor, microcontroller, application specific integrated circuit (ASIC), or any other form of electronic controller known in the art. The controller  40  is operably coupled to one or more components of the air conditioning system  20 , such as the movement mechanism  26  or a compressor (not shown) for example, to control operation thereof. A thermostat  42  for selecting a temperature demand of the area to be conditioned by the air conditioning system  20  is arranged in communication with the controller  40 . In an embodiment, the controller  40  is configured to control operation of the air conditioning system  20  in response to the temperature setting of the thermostat  42 . 
     In an embodiment, the air conditioning system  20  additionally includes at least one sensor  44  operable to automatically monitor a pH level of the condensate within the drain pan  30 . The sensor  44  may be mounted directly within the condensate drain pan  30  or within a conduit fluidly coupled to the drain pan  30 . Alternatively, the sensor  44  may be mounted at any other suitable location, including at a location external to air conditioning system  20  where condensate is collected, such as the condensate line or drain pipe  32  for example. The sensor  44  may be configured to continuously monitor and communicate the pH level of the condensate to the controller  40 , or alternatively, may be configured to intermittently monitor and communicate the pH level of the condensate to the controller  40 . 
     In response to a signal from the pH sensor  44 , the controller  40  may be configured to evaluate a condition of the heat exchanger  22 , such as the blockage of the flow across or through the fins of the heat exchanger  22 . In an embodiment, the pH level is compared to at least one threshold. If the sensed pH level is above a first threshold, such as above a pH level of 6 for example, the controller  40  may be configured to determine that the heat exchanger  22  is in an acceptable condition. In such embodiments, the air conditioning system  20  will continue to operate normally. 
     However, if the sensed pH level is below the first threshold, the pH level may indicate that particulate matter has accumulated on the heat exchanger  22 . In such instances, the controller  40  may be configured to indicate a need for service. The indicator may be associated with a component of the air conditioning system  20  that is visible by a user. For example, the controller  40  may display a message on the thermostat that service of the air conditioning system  20 , and in some embodiments heat exchanger  22 , is required. In another embodiment, the controller  40  may operate an indicator associated with a component of the air conditioning system  20  that is typically visible by a service man during a maintenance operation. For example, the controller  40  may energize a light that indicates to the service man that maintenance of the heat exchanger  22  is required. 
     The controller  40  may alternatively or additionally be configured to either directly or indirectly place a request for service. In an embodiment, the controller  40  is able to communicate with a remote system, such as a cloud-based system (illustrated schematically at  46 ) for example, the need for service. Based on the sensed pH level, the controller  40  will determine the urgency of the service. For example, if the sensed pH level is below a second threshold, the controller  40  may be configured to request immediate service of the air conditioning system  20 . The second threshold may correspond to instances when the air flow at the heat exchanger  22  is reduced by at least 50%. However, it should be understood that any suitable threshold is within the scope of the disclosure. 
     In embodiments where the sensed pH level is between the first threshold and the second threshold, the controller  40  may determine an approximate date by which service is required in the future. In an embodiment, the future service date is based on an estimation of when the pH level of the particulate matter will fall below the second threshold. 
     Alternatively, or in addition, a service man may be able to manually determine a condition of the heat exchanger  22  without actually seeing the heat exchanger  22 . In an embodiment, during a maintenance operation, a service man will measure the pH level of the condensate within the condensate drain pan  30  using a commercially available standard pH test strip, a pH meter, and/or a colorimeter. The service man will then compare the pH level indicated by the test strip to a correlated table, which will identify a condition of heat exchanger  22  and whether maintenance of the heat exchanger, specifically cleaning of the debris accumulated of the exterior of the heat exchanger  22 , is required. In an embodiment, the service man may perform maintenance in response to the condition of the heat exchanger  22 . However, in other embodiments, the table may indicate or suggest a future date by which maintenance of the heat exchanger  22  should be performed. 
     Monitoring of the pH level of the condensate of a heat exchanger  22 , such as an evaporator for example, provides a cost effective mechanism for accurately indicating the condition of the particulate matter accumulated on the evaporator. By actively identifying clogging, maintenance of the heat exchanger can be expedited, thereby minimizing the wear and tear on the remainder of the air conditioning system  20 , and reducing the operating costs of the air conditioning system  20 . 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. 
     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. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.