ENERGY RECOVERY IN A MAKE-UP AIR MODULE OF AN AIR CONDITIONER APPLIANCE

Abstract

An air conditioner unit includes a bulkhead defining an indoor portion and an outdoor portion, an intake aperture and an exhaust aperture defined in the bulkhead, an intake fan fluidly coupled to the intake aperture for urging a flow of make-up air through the intake aperture into the indoor portion and an exhaust fan fluidly coupled to the exhaust aperture for urging a flow of exhaust air through the exhaust aperture into the outdoor portion, and a heat transfer assembly extending between the intake aperture and the exhaust aperture for transferring thermal energy between the flow of make-up air and the flow of exhaust air.

Claims

1. An air conditioner unit, comprising: a bulkhead defining an indoor portion and an outdoor portion; an intake aperture and an exhaust aperture defined in the bulkhead; an intake fan fluidly coupled to the intake aperture for urging a flow of make-up air through the intake aperture into the indoor portion and an exhaust fan fluidly coupled to the exhaust aperture for urging a flow of exhaust air through the exhaust aperture into the outdoor portion; and a heat transfer assembly extending between the intake aperture and the exhaust aperture for transferring thermal energy between the flow of make-up air and the flow of exhaust air.

2. The air conditioner unit of claim 1, wherein the heat transfer assembly comprises: a heat pipe that extends from the intake aperture to the exhaust aperture.

3. The air conditioner unit of claim 2, wherein the heat transfer assembly further comprises: a plurality of heat exchange fins thermally coupled to the heat pipe and extending across both the intake aperture and the exhaust aperture.

4. The air conditioner unit of claim 1, wherein the heat transfer assembly is positioned on the bulkhead in the outdoor portion.

5. The air conditioner unit of claim 1, wherein the heat transfer assembly further comprises: an intake housing positioned over the intake fan and the intake aperture; and an exhaust housing positioned over the exhaust fan and the exhaust aperture.

6. The air conditioner unit of claim 1, wherein the intake fan and the exhaust fan are axial fans.

7. The air conditioner unit of claim 1, wherein the intake aperture and the exhaust aperture are positioned on opposite sides of the bulkhead along a lateral direction.

8. The air conditioner unit of claim 1, further comprising: an intake door pivotally mounted over the intake aperture and being movable between an open position to permit the flow of make-up air and a closed position to restrict the flow of make-up air; and an exhaust door pivotally mounted over the exhaust aperture and being movable between an open position to permit the flow of exhaust air and a closed position to restrict the flow of exhaust air.

9. The air conditioner unit of claim 1, wherein the heat transfer assembly further comprises: a filter positioned over the intake aperture for filtering the flow of make-up air.

10. The air conditioner unit of claim 1, further comprising: a controller operably coupled to the intake fan and the exhaust fan, the controller being configured to operate the intake fan and the exhaust fan at a target fan speed for generating a target flow rate.

11. The air conditioner unit of claim 10, wherein the target flow rate is between about 30 and 40 cubic feet per minute.

12. The air conditioner unit of claim 1, further comprising: an occupancy detection sensor; and a controller operably coupled to the occupancy detection sensor, the controller being configured to: detect occupant presence using the occupancy detection sensor; and operate the intake fan and the exhaust fan in response to detecting occupant presence.

13. A heat transfer assembly for an air conditioner unit, the air conditioner unit comprising a bulkhead defining an indoor portion, an outdoor portion, an intake aperture, and an exhaust aperture, the heat transfer assembly comprising: an intake fan fluidly coupled to the intake aperture for urging a flow of make-up air through the intake aperture into the indoor portion and an exhaust fan fluidly coupled to the exhaust aperture for urging a flow of exhaust air through the exhaust aperture into the outdoor portion; and a heat pipe that extends from the intake aperture to the exhaust aperture for transferring thermal energy between the flow of make-up air and the flow of exhaust air.

14. The heat transfer assembly of claim 13, further comprising: a plurality of heat exchange fins thermally coupled to the heat pipe and extending across both the intake aperture and the exhaust aperture.

15. The heat transfer assembly of claim 13, wherein the heat transfer assembly is positioned on the bulkhead in the outdoor portion.

16. The heat transfer assembly of claim 13, further comprising: an intake housing positioned over the intake fan and the intake aperture; and an exhaust housing positioned over the exhaust fan and the exhaust aperture.

17. The heat transfer assembly of claim 13, wherein the intake fan and the exhaust fan are axial fans.

18. The heat transfer assembly of claim 13, wherein the intake aperture and the exhaust aperture are positioned on opposite sides of the bulkhead along a lateral direction.

19. The heat transfer assembly of claim 13, further comprising: an intake door pivotally mounted over the intake aperture and being movable between an open position to permit the flow of make-up air and a closed position to restrict the flow of make-up air; and an exhaust door pivotally mounted over the exhaust aperture and being movable between an open position to permit the flow of exhaust air and a closed position to restrict the flow of exhaust air.

20. The heat transfer assembly of claim 13, further comprising: an occupancy detection sensor; and a controller operably coupled to the occupancy detection sensor, the controller being configured to: detect occupant presence using the occupancy detection sensor; and operate the intake fan and the exhaust fan in response to detecting occupant presence.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

[0011] FIG. 1 provides a perspective view of an air conditioner unit, with part of an indoor portion exploded from a remainder of the air conditioner unit for illustrative purposes, in accordance with one exemplary embodiment of the present disclosure.

[0012] FIG. 2 is another perspective view of components of the indoor portion of the exemplary air conditioner unit of FIG. 1.

[0013] FIG. 3 is a schematic view of a refrigeration loop in accordance with one embodiment of the present disclosure.

[0014] FIG. 4 is a rear perspective view of an outdoor portion of the exemplary air conditioner unit of FIG. 1, illustrating a vent aperture in a bulkhead in accordance with one embodiment of the present disclosure.

[0015] FIG. 5 is a front perspective view of the exemplary bulkhead of FIG. 4 with a primary vent door illustrated in the open position in accordance with one embodiment of the present disclosure.

[0016] FIG. 6 is a rear perspective view of the exemplary air conditioner unit and bulkhead of FIG. 4 including a heat transfer assembly in accordance with one embodiment of the present disclosure.

[0017] FIG. 7 is another rear perspective view of the exemplary air conditioner unit and bulkhead of FIG. 4 including the example heat transfer assembly of FIG. 6.

[0018] FIG. 8 is another rear perspective view of the exemplary air conditioner unit and bulkhead of FIG. 4 including the example heat transfer assembly of FIG. 6.

[0019] FIG. 9 is a front view of the exemplary air conditioner unit and bulkhead of FIG. 4 including the example heat transfer assembly of FIG. 6.

[0020] FIG. 10 is an exploded view of the example heat transfer assembly of FIG. 6.

[0021] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

DETAILED DESCRIPTION

[0022] Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0023] As used herein, the term or is generally intended to be inclusive (i.e., A or B is intended to mean A or B or both). The terms first, second, and third may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms upstream and downstream refer to the relative flow direction with respect to fluid flow in a fluid pathway. For example, upstream refers to the flow direction from which the fluid flows, and downstream refers to the flow direction to which the fluid flows. Furthermore, as used herein, terms of approximation, such as approximately, substantially, or about, refer to being within a ten percent margin of error.

[0024] Referring now to FIGS. 1 and 2, an air conditioner unit 10 is provided. The air conditioner unit 10 is a one-unit type air conditioner, also conventionally referred to as a room air conditioner or a packaged terminal air conditioner (PTAC). The unit 10 includes an indoor portion 12 and an outdoor portion 14, and generally defines a vertical direction V, a lateral direction L, and a transverse direction T. Each direction V, L, T is perpendicular to each other, such that an orthogonal coordinate system is generally defined. Although aspects of the present subject matter are described with reference to PTAC unit 10, it should be appreciated that aspects of the present subject matter may be equally applicable to other air conditioner unit types and configurations, such as single package vertical units (SPVUs) and split heat pump systems.

[0025] A housing 20 of the unit 10 may contain various other components of the unit 10. Housing 20 may include, for example, a rear grill 22 and a room front 24 which may be spaced apart along the transverse direction T by a wall sleeve 26. The rear grill 22 may be part of the outdoor portion 14, and the room front 24 may be part of the indoor portion 12. Components of the outdoor portion 14, such as an outdoor heat exchanger 30, an outdoor fan 32, and a compressor 34 may be housed within the wall sleeve 26. A fan shroud 36 may additionally enclose outdoor fan 32, as shown.

[0026] Indoor portion 12 may include, for example, an indoor heat exchanger 40, a blower fan or indoor fan 42, and a heating unit 44. These components may, for example, be housed behind the room front 24. Additionally, a bulkhead 46 may generally support and/or house various other components or portions thereof of the indoor portion 12, such as indoor fan 42 and the heating unit 44. Bulkhead 46 may generally separate and define the indoor portion 12 and outdoor portion 14.

[0027] Outdoor and indoor heat exchangers 30, 40 may be components of a sealed system or refrigeration loop 48, which is shown schematically in FIG. 3. Refrigeration loop 48 may, for example, further include compressor 34 and an expansion device 50. As illustrated, compressor 34 and expansion device 50 may be in fluid communication with outdoor heat exchanger 30 and indoor heat exchanger 40 to flow refrigerant therethrough as is generally understood. More particularly, refrigeration loop 48 may include various lines for flowing refrigerant between the various components of refrigeration loop 48, thus providing the fluid communication there between. Refrigerant may thus flow through such lines from indoor heat exchanger 40 to compressor 34, from compressor 34 to outdoor heat exchanger 30, from outdoor heat exchanger 30 to expansion device 50, and from expansion device 50 to indoor heat exchanger 40. The refrigerant may generally undergo phase changes associated with a refrigeration cycle as it flows to and through these various components, as is generally understood. Suitable refrigerants for use in refrigeration loop 48 may include pentafluoroethane, difluoromethane, or a mixture such as R410a, although it should be understood that the present disclosure is not limited to such examples and rather that any suitable refrigerant may be utilized.

[0028] As is understood in the art, refrigeration loop 48 may be alternately operated as a refrigeration assembly (and thus perform a refrigeration cycle) or a heat pump (and thus perform a heat pump cycle). As shown in FIG. 3, when refrigeration loop 48 is operating in a cooling mode and thus performing a refrigeration cycle, the indoor heat exchanger 40 acts as an evaporator and the outdoor heat exchanger 30 acts as a condenser. Alternatively, when the assembly is operating in a heating mode and thus performs a heat pump cycle, the indoor heat exchanger 40 acts as a condenser and the outdoor heat exchanger 30 acts as an evaporator. The outdoor and indoor heat exchangers 30, 40 may each include coils through which a refrigerant may flow for heat exchange purposes, as is generally understood.

[0029] According to an example embodiment, compressor 34 may be a variable speed compressor. In this regard, compressor 34 may be operated at various speeds depending on the current air conditioning needs of the room and the demand from refrigeration loop 48. For example, according to an exemplary embodiment, compressor 34 may be configured to operate at any speed between a minimum speed, e.g., 1500 revolutions per minute (RPM), to a maximum rated speed, e.g., 3500 RPM. Notably, use of variable speed compressor 34 enables efficient operation of refrigeration loop 48 (and thus air conditioner unit 10), minimizes unnecessary noise when compressor 34 does not need to operate at full speed, and ensures a comfortable environment within the room.

[0030] Specifically, according to an exemplary embodiment, compressor 34 may be an inverter compressor. In this regard, compressor 34 may include a power inverter, power electronic devices, rectifiers, or other control electronics suitable for converting an alternating current (AC) power input into a direct current (DC) power supply for the compressor. The inverter electronics may regulate the DC power output to any suitable DC voltage that corresponds to a specific operating speed of compressor. In this manner compressor 34 may be regulated to any suitable operating speed, e.g., from 0% to 100% of the full rated power and/or speed of the compressor. This may facilitate precise compressor operation at the desired operating power and speed, thus meeting system needs while maximizing efficiency and minimizing unnecessary system cycling, energy usage, and noise.

[0031] In exemplary embodiments as illustrated, expansion device 50 may be disposed in the outdoor portion 14 between the indoor heat exchanger 40 and the outdoor heat exchanger 30. According to the exemplary embodiment, expansion device 50 may be an electronic expansion valve (EEV) that enables controlled expansion of refrigerant, as is known in the art. According to alternative embodiments, expansion device 50 may be a capillary tube or another suitable expansion device configured for use in a thermodynamic cycle.

[0032] More specifically, according to exemplary embodiments, electronic expansion device 50 may be configured to precisely control the expansion of refrigerant to maintain, for example, a desired temperature differential of the refrigerant across the evaporator (i.e., the outdoor heat exchanger 30 in heat pump mode). In other words, electronic expansion device 50 throttles the flow of refrigerant based on the reaction of the temperature differential across the evaporator or the amount of superheat temperature differential, thereby ensuring that the refrigerant is in the gaseous state entering compressor 34.

[0033] In general, the terms superheat, operating superheat, or the like are generally intended to refer to the temperature increase of the refrigerant past the fully saturated vapor temperature in the evaporator. In this regard, for example, the superheat may be quantified in degrees Fahrenheit, e.g., such that 1 F. superheat means that the refrigerant exiting the evaporator is 1 F. higher than the saturated vapor temperature. It should be appreciated that the operating superheat may be measured and monitored by controller 64 in any suitable manner. For example, controller 64 may be operably coupled to a pressure sensor for measuring the refrigerant pressure exiting the evaporator, may convert that pressure to the saturated vapor temperature, and may subtract that temperature from the measured refrigerant temperature at the evaporator outlet to determine superheat.

[0034] According to exemplary embodiments, expansion device or electronic expansion valve 50 may be driven by a stepper motor or other drive mechanism to any desirable position between a fully closed position (e.g., when no refrigerant passes through EEV 50) to a fully open position (e.g., when there is little or no restriction through the EEV 50). For example, controller 64 may be operably coupled to EEV 50 and may regulate the position of the EEV 50 through a control signal to achieve a target superheat, a target restriction/expansion, etc.

[0035] More specifically, the control signal communicated from controller 64 may specify the number of control steps (or simply steps) and a corresponding direction (e.g., counterclockwise toward the closed position or clockwise toward the open position). Each EEV 50 may have a physical stroke span equal to the difference between the fully open position and the fully closed position. In addition, the EEV 50 may include a step range or range of control steps that correspond to the number adjustment steps it takes for the EEV 50 to travel from the fully closed position to the fully open position.

[0036] Each step may refer to a predetermined rotation of the drive mechanism, e.g., such as a stepper motor, which may in turn move the EEV 50 a fixed linear distance toward the open or closed position (depending on the commanded step direction). For example, according to the exemplary embodiment, the EEV 50 may have a step range of 500 steps, with 0 steps corresponding to fully closed and 500 steps corresponding to fully open. However, it should be appreciated that according to alternative embodiments, any given electronic expansion valve may include a different number of control steps, and the absolute step adjustments described herein may be varied accordingly.

[0037] In addition, as used herein, the position of EEV 50 may be expressed as a percentage, e.g., where 0% corresponds to a fully closed position and 100% corresponds to a fully open position. According to exemplary embodiments, this percentage representation may also refer to the percentage of total control steps taken from the closed position, e.g., with 10% referring to 50 steps (e.g., 10% of the 500 total steps), 100% referring to 400 steps (e.g., 100% of 500 total steps), etc.

[0038] According to the illustrated exemplary embodiment, outdoor fan 32 is an axial fan and indoor fan 42 is a centrifugal fan. However, it should be appreciated that according to alternative embodiments, outdoor fan 32 and indoor fan 42 may be any suitable fan type. In addition, according to an exemplary embodiment, outdoor fan 32 and indoor fan 42 are variable speed fans, e.g., similar to variable speed compressor 34. For example, outdoor fan 32 and indoor fan 42 may rotate at different rotational speeds, thereby generating different air flow rates. It may be desirable to operate fans 32, 42 at less than their maximum rated speed to ensure safe and proper operation of refrigeration loop 48 at less than its maximum rated speed, e.g., to reduce noise when full speed operation is not needed. In addition, according to alternative embodiments, fans 32, 42 may be operated to urge make-up air into the room.

[0039] According to the illustrated embodiment, indoor fan 42 may operate as an evaporator fan in refrigeration loop 48 to encourage the flow of air through indoor heat exchanger 40. Accordingly, indoor fan 42 may be positioned downstream of indoor heat exchanger 40 along the flow direction of indoor air and downstream of heating unit 44. Alternatively, indoor fan 42 may be positioned upstream of indoor heat exchanger 40 along the flow direction of indoor air and may operate to push air through indoor heat exchanger 40.

[0040] Heating unit 44 in exemplary embodiments includes one or more heater banks 60. Each heater bank 60 may be operated as desired to produce heat. In some embodiments as shown, three heater banks 60 may be utilized. Alternatively, however, any suitable number of heater banks 60 may be utilized. Each heater bank 60 may further include at least one heater coil or coil pass 62, such as in exemplary embodiments two heater coils or coil passes 62. Alternatively, other suitable heating elements may be utilized.

[0041] The operation of air conditioner unit 10 including compressor 34 (and thus refrigeration loop 48 generally) indoor fan 42, outdoor fan 32, heating unit 44, expansion device 50, and other components of refrigeration loop 48 may be controlled by a processing device such as a controller 64. Controller 64 may be in communication (via for example a suitable wired or wireless connection) to such components of the air conditioner unit 10. Controller 64 may include a memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of unit 10. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor.

[0042] Unit 10 may additionally include a control panel 66 and one or more user inputs 68, which may be included in control panel 66. The user inputs 68 may be in communication with the controller 64. A user of the unit 10 may interact with the user inputs 68 to operate the unit 10, and user commands may be transmitted between the user inputs 68 and controller 64 to facilitate operation of the unit 10 based on such user commands. A display 70 may additionally be provided in the control panel 66 and may be in communication with the controller 64. Display 70 may, for example be a touchscreen or other text-readable display screen, or alternatively may simply be a light that can be activated and deactivated as required to provide an indication of, for example, an event or setting for the unit 10.

[0043] Referring now generally to FIGS. 1 through 5, operation of unit 10 will be described according to an exemplary embodiment. More specifically, the operation of components within indoor portion 12 will be described during a cooling operation or cooling cycle of unit 10. Although a cooling cycle will be described, it should be further appreciated that indoor heat exchanger 40 and/or heating unit 44 be used to heat indoor air according to alternative embodiments. Moreover, although operation of unit 10 is described below for the exemplary packaged terminal air conditioner unit, it should be further appreciated that aspects the present subject matter may be used in any other suitable air conditioner unit, such as a heat pump or split unit system.

[0044] As illustrated, room front 24 of unit 10 generally defines an intake vent 80 and a discharge vent 82 for use in circulating a flow of air throughout a room. In this regard, indoor fan 42 is generally configured for drawing in air through intake vent 80 and urging the flow of air through indoor heat exchanger 40 before discharging the air out of discharge vent 82. According to the illustrated embodiment, intake vent 80 is positioned proximate a bottom of unit 10 and discharge vent 82 is positioned proximate a top of unit 10. However, it should be appreciated that according to alternative embodiments, intake vent 80 and discharge vent 82 may have any other suitable size, shape, position, or configuration.

[0045] During a cooling cycle, refrigeration loop 48 is generally configured for urging cold refrigerant through indoor heat exchanger 40 in order to lower the temperature of the flow of air before discharging it back into the room. Specifically, during a cooling operation, controller 64 may be provided with a target temperature, e.g., as set by a user for the desired room temperature. In general, components of refrigeration loop 48, outdoor fan 32, indoor fan 42, and other components of unit 10 operate to continuously cool the flow of air.

[0046] In order to facilitate operation of refrigeration loop 48 and other components of unit 10, unit 10 may include a variety of sensors for detecting conditions internal and external to the unit 10. These conditions can be fed to controller 64 which may make decisions regarding operation of unit 10 to rectify undesirable conditions or to otherwise condition the flow of air into the room. For example, unit 10 may include an indoor temperature sensor 86 which is positioned and configured for measuring the indoor temperature within the room. In addition, unit 10 may include an indoor humidity sensor 88 which is positioned and configured for measuring the indoor humidity within the room. In this manner, unit 10 may be used to regulate the flow of air into the room until the measured indoor temperature reaches the desired target temperature and/or humidity level. According to exemplary embodiments, unit 10 may further include an outdoor temperature sensor for measuring ambient outdoor temperatures.

[0047] As used herein, temperature sensor or the equivalent is intended to refer to any suitable type of temperature measuring system or device positioned at any suitable location for measuring the desired temperature. Thus, for example, temperature sensor 86 may each be any suitable type of temperature sensor, such as a thermistor, a thermocouple, a resistance temperature detector, a semiconductor-based integrated circuit temperature sensor, etc. In addition, temperature sensor 86 may be positioned at any suitable location and may output a signal, such as a voltage, to a controller that is proportional to and/or indicative of the temperature being measured. Although exemplary positioning of temperature sensors is described herein, it should be appreciated that unit 10 may include any other suitable number, type, and position of temperature, and/or other sensors according to alternative embodiments.

[0048] As used herein, the terms humidity sensor or the equivalent may be intended to refer to any suitable type of humidity measuring system or device positioned at any suitable location for measuring the desired humidity. Thus, for example, humidity sensor 88 may refer to any suitable type of humidity sensor, such as capacitive digital sensors, resistive sensors, and thermal conductivity humidity sensors. In addition, humidity sensor 88 may be positioned at any suitable location and may output a signal, such as a voltage, to a controller that is proportional to and/or indicative of the humidity being measured. Although exemplary positioning of humidity sensors is described herein, it should be appreciated that unit 10 may include any other suitable number, type, and position of humidity sensors according to alternative embodiments.

[0049] Referring again to FIG. 1, a schematic diagram of an external communication system 90 will be described according to an exemplary embodiment of the present subject matter. In general, external communication system 90 is configured for permitting interaction, data transfer, and other communications between air conditioner unit 10 and one or more external devices. For example, this communication may be used to provide and receive operating parameters, user instructions or notifications, performance characteristics, user preferences, or any other suitable information for improved performance of air conditioner unit 10. In addition, it should be appreciated that external communication system 90 may be used to transfer data or other information to improve performance of one or more external devices or appliances and/or improve user interaction with such devices.

[0050] For example, external communication system 90 permits controller 64 of air conditioner unit 10 to communicate with a separate device external to air conditioner unit 10, referred to generally herein as an external device 92. As described in more detail below, these communications may be facilitated using a wired or wireless connection, such as via a network 94. In general, external device 92 may be any suitable device separate from air conditioner unit 10 that is configured to provide and/or receive communications, information, data, or commands from a user. In this regard, external device 92 may be, for example, a personal phone, a smartphone, a tablet, a laptop or personal computer, a wearable device, a smart home system, or another mobile or remote device.

[0051] In addition, a remote server 96 may be in communication with air conditioner unit 10 and/or external device 92 through network 94. In this regard, for example, remote server 96 may be a cloud-based server 96, and is thus located at a distant location, such as in a separate state, country, etc. According to an exemplary embodiment, external device 92 may communicate with a remote server 96 over network 94, such as the Internet, to transmit/receive data or information, provide user inputs, receive user notifications or instructions, interact with or control air conditioner unit 10, etc. In addition, external device 92 and remote server 96 may communicate with air conditioner unit 10 to communicate similar information.

[0052] In general, communication between air conditioner unit 10, external device 92, remote server 96, and/or other user devices or appliances may be carried using any type of wired or wireless connection and using any suitable type of communication network, non-limiting examples of which are provided below. For example, external device 92 may be in direct or indirect communication with air conditioner unit 10 through any suitable wired or wireless communication connections or interfaces, such as network 94. For example, network 94 may include one or more of a local area network (LAN), a wide area network (WAN), a personal area network (PAN), the Internet, a cellular network, any other suitable short- or long-range wireless networks, etc. In addition, communications may be transmitted using any suitable communications devices or protocols, such as via Wi-Fi, Bluetooth, Zigbee, wireless radio, laser, infrared, Ethernet type devices and interfaces, etc. In addition, such communication may use a variety of communication protocols (e.g., TCP/IP, HTTP, SMTP, FTP), encodings or formats (e.g., HTML, XML), and/or protection schemes (e.g., VPN, secure HTTP, SSL).

[0053] External communication system 90 is described herein according to an exemplary embodiment of the present subject matter. However, it should be appreciated that the exemplary functions and configurations of external communication system 90 provided herein are used only as examples to facilitate description of aspects of the present subject matter. System configurations may vary, other communication devices may be used to communicate directly or indirectly with one or more associated appliances, other communication protocols and steps may be implemented, etc. These variations and modifications are contemplated as within the scope of the present subject matter.

[0054] As explained briefly above, it may be desirable to periodically supplement the indoor air with make-up air from the outdoors. Accordingly, referring briefly to FIG. 4, an intake aperture 100 may be defined in bulkhead 46 for providing fluid communication between indoor portion 12 and outdoor portion 14. In addition, an exhaust aperture 102 may be defined in bulkhead 46 for providing fluid communication between outdoor portion 12 and indoor portion 14. According to the illustrated example embodiment, intake aperture 100 and exhaust aperture 102 are positioned on opposite sides of the bulkhead along a lateral direction L, thereby ensuring that the two flows are separated from each other.

[0055] Specifically, as described in more detail below, a flow of intake air or make-up air (e.g., identified by arrow 104 in FIG. 6) may pass into indoor portion 12 through intake aperture 100. In this regard, in some cases it may be desirable to allow outside air (i.e., make-up air) to flow into the room in order, e.g., to meet government regulations, to compensate for negative pressure created within the room, etc. In addition, a flow of exhaust air (e.g., identified by arrow 106 in FIG. 6) may pass into outdoor portion 14 through exhaust aperture 102. As will be described in more detail below, the flow of exhaust air may be used for transferring thermal energy between the two flows of air for improved occupant comfort.

[0056] As shown in FIGS. 5 and 9, vent doors may be pivotally mounted to the bulkhead 46 proximate intake aperture 100 and exhaust aperture 102. These doors may selectively open and close these apertures and regulate airflow therethrough. More specifically, as illustrated, an intake door 110 is pivotally mounted over intake aperture 100 and is movable between an open position to permit the flow of make-up air 104 and a closed position to restrict the flow of make-up air 104. Similarly, an exhaust door 112 is pivotally mounted over exhaust aperture 102 and is movable between an open position to permit the flow of exhaust air 106 and a closed position to restrict the flow of exhaust air 106. As shown, intake door 110 and exhaust door 112 are mounted to the indoor facing surface of indoor portion 12. According to the illustrated embodiment intake door 110 and exhaust door 112 may be pivoted between the open and closed position by one or more electric motors 114 (see, e.g., FIG. 5) controlled by controller 64, or by any other suitable method.

[0057] As best illustrated in FIGS. 6 through 10, air conditioner unit 10 may further include one or more fan assemblies for selectively urging the flow of make-up air 104 and the flow of exhaust air 106. In this regard, as illustrated, air conditioner unit 10 may generally include an intake fan 120 fluidly coupled to intake aperture 100 for urging the flow of makeup air 104 into indoor portion 12 through intake aperture 100. Similarly, air conditioner unit 10 may generally include an exhaust fan 122 fluidly coupled to exhaust aperture 102 for urging the flow of exhaust air 106 into outdoor portion 14 through exhaust aperture 102.

[0058] For example, according to the illustrated embodiment, intake fan 120 and exhaust fan 122 are positioned on bulkhead 46 within outdoor portion 14 over intake aperture 100 and exhaust aperture 102, respectively. In addition, according to an example embodiment, the flow of exhaust air 106 may be routed through a duct directly to a condenser shroud or fan shroud 36 that is positioned around outdoor heat exchanger 30. In this manner, the flow of exhaust air 106 may be fluidly isolated or separated from the flow of makeup air 104. In addition, the flow of exhaust air 106 may transfer thermal energy with outdoor heat exchanger 30.

[0059] According to the illustrated embodiment, both intake fan 120 and exhaust fan 122 are axial fans (e.g., muffin fans). However, it should be appreciated that any other suitable number, type, and configuration of fan or blower could be used to urge a flow of makeup air 104 and exhaust air 106 according to alternative embodiments. In addition, intake fan 120 and exhaust fan 122 may be positioned in any other suitable location within air conditioner unit 10. The embodiments described herein are only exemplary and are not intended to limit the scope of the present subject matter.

[0060] According to example embodiments, controller 64 of unit 10 may be operably coupled to intake fan 120 and exhaust fan 122 for regulating the flow of make-up air 104 and the flow of exhaust air 106, respectively. It should be appreciated that these fans may be operated at the same speed or at a different speed depending on ambient conditions in the room or outside conditions. For example, the flow rate of the flow of make-up air 104 is typically dictated by the make-up air needs within the room, e.g., based on government regulations, occupancy, bathroom fan operation, etc. Similarly, the outside temperature and humidity may require different flow rates of the flow of exhaust air 106 to suitably condition the flow of make-up air 104 prior to introduction into the room.

[0061] Thus, according to example embodiments, controller 64 may dynamically adjust the flow rates of each of the flow of make-up air 104 and the flow of exhaust air 106 depending on various atmospheric and operating conditions. According to an example embodiment, it may be desirable to operate the intake fan 120 and exhaust fan 122 at the same flow rate. In general, the target flow rate for the flow of make-up air 104 and the flow of exhaust air 106 may be between about 10 and 60 cubic feet per minute (cfm), between about 20 and 50 cfm, between about 30 and 40 cfm, or about 35 cfm.

[0062] According to the illustrated embodiment, air conditioner unit 10 may further include an intake housing 124 positioned over intake fan 120 and intake aperture 100. In addition, air conditioner unit 10 may further include an exhaust housing 126 positioned over exhaust fan 122 and exhaust aperture 102. For example, intake housing 124 and exhaust housing 126 may generally be configured to contain system components and prevent undesirable air leakage.

[0063] Referring now specifically to FIG. 10, it may be desirable to filter the flow of makeup air 104 before introducing it into indoor portion 12. Accordingly, air conditioner unit 10 may further include a filter 130 that is positioned within intake housing 124 over intake aperture for filtering the flow of makeup air 104. It should be appreciated that filter 130 may be any suitable type, position, and configuration of filtering mechanisms. For example, filter 130 may be a screen filter, a pleated filter, an electrostatic filter, a carbon filter, a fiber glass filter, or any other suitable type of filter. Although filter 130 is illustrated as being positioned upstream of intake fan 120, it should be appreciated that filter 130 may alternatively be positioned at any other suitable location within the flow path of the flow of make-up air 104.

[0064] In some cases, it may be desirable to treat or condition make-up air flowing through intake aperture 100 prior to blowing it into the room. For example, outdoor air which has a relatively low or high temperature or humidity may require treating before passing into the room. In this regard, if it is very cold outside, the flow of makeup air 104 may be cool or frigid, and injecting such air into the flow of indoor air may result in poor system efficiency and user dissatisfaction. By contrast, if it is very warm outside, it may be desirable to lower the temperature of the flow of makeup air 104 before injecting it into the room. Therefore, as illustrated in FIGS. 6 through 10, unit 10 may further include a heat transfer assembly 140 extending between intake aperture 100 and exhaust aperture 102 for transferring thermal energy between the flow of make-up air 104 and the flow of exhaust air 106, as will be described in more detail below.

[0065] As best illustrated in FIG. 10, heat transfer assembly 140 may generally include a heat pipe 142 that extends from intake aperture 100 to exhaust aperture 102. In general, heat pipe 142 is intended to transfer thermal energy between the flow of make-up air 104 and the flow of exhaust air 106. As used herein, the term heat pipe and the like are intended to refer to any suitable device or heat exchanger for transferring thermal energy through the evaporation and condensation of a working fluid within a cavity. In this regard, heat pipes 142 may provide thermal communication between intake aperture 100 and exhaust aperture 102, e.g., by harnessing and transferring thermal energy from airflows passing therethrough.

[0066] In general, heat pipe 142 may include a sealed casing containing a working fluid. The casing is preferably constructed of a material with a high thermal conductivity, such as a metal, such as copper or aluminum. In some embodiments, the working fluid may be water. In other embodiments, suitable working fluids for heat pipe 142 includes acetone, methanol, ethanol, or toluene. Any suitable fluid may be used for the working 154, e.g., any fluid that is compatible with the material of the casing 152 and is suitable for the desired operating temperature range.

[0067] According to the illustrated embodiment, heat pipe 142 generally extends between a condenser section at one end of heat pipe 142 and an evaporator section at an opposite end of heat pipe 142 (e.g., with the evaporator/condenser section being dependent on the relative indoor/outdoor temperatures). The working fluid contained within the casing of heat pipe 142 absorbs thermal energy at the evaporator section, whereupon the working fluid travels in a gaseous state from the evaporator section to the condenser section. At the condenser section, the gaseous working fluid condenses to a liquid state and thereby releases thermal energy.

[0068] According to exemplary embodiments, heat pipe 142 may further include an internal wick structure to transport liquid the working fluid from the condenser section to the evaporator section by capillary flow. According to an exemplary embodiment, heat pipe 142 may include a plurality of surface aberrations, protrusions, or fins (not shown) for increasing the rate of thermal transfer. In this regard, heat transfer assembly 140 may include a plurality of heat transfer fins 144 that extend across both intake aperture 100 and exhaust aperture 104. Such heat exchange fins 144 may provide an increased contact area between the heat pipe 142, the flow of make-up air 104, and the flow of exhaust air 106.

[0069] According to example embodiments, the operation of air conditioner unit 10 and heat transfer assembly 140 may depend on the presence of occupants within the room being conditioned. Accordingly, unit 10 may further include an occupancy detection sensor 160 for detecting room occupancy. For example, occupancy detection sensor 160 may be a motion sensor, a proximity sensor, or any other suitable sensor positioned on the room front 24 of unit 10. According to still other embodiments, occupancy detection sensor 160 may be a thermostat, a room door sensor, a keycard access pad, or any other suitable device capable of detecting room occupancy and communicating such a status to controller 64 of unit 10.

[0070] According to an example embodiment, controller 64 may generally be configured to detect occupant presence using the occupancy detection sensor 160 and operate the heat transfer assembly 140 in response to detecting occupant presence. In this regard, for example, when an occupant is detected, controller 64 may operate intake fan 120 at a target air flow rate (e.g., 35 cfm). If it is cool outside and the flow of air is too cool for occupant comfort, e.g., as measured by a temperature sensor (e.g., indoor temperature sensor 86), controller 64 may operate exhaust fan 122 at a target flow rate (e.g., also 35 cfm), thereby passing relatively warm air through the heat transfer assembly 140 to heat the flow of make-up air 104.

[0071] As explained herein, aspects of the present subject matter are generally directed to a PTAC unit enhanced with heat recovery ventilation (HRV) or energy recovery ventilation (ERV) technology. This improvement aims to boost the efficiency of the unit, particularly when it incorporates makeup air functionality. To achieve this energy recovery, a second vent hole may be added to the mouse hole area of the PTAC bulkhead. This new opening may serve as a fresh air exhaust directed towards the condenser. On the rear side of the bulkhead, a compact heat pipe system may be fitted between the existing make up air opening and the new exhaust vent hole. This exhaust vent hole could be employed with a muffin fan or rely on the suction of the condenser fan so that to provide airflow across the heat pipe. The functioning of this system may depend on the settings chosen by the occupant.

[0072] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.