Patent Publication Number: US-2016223239-A1

Title: Indoor Liquid/Suction Heat Exchanger

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 62/110,496 filed on Jan. 31, 2015 by Stephen Stewart Hancock, and entitled “Indoor Liquid/Suction Heat Exchanger,” the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     BACKGROUND 
     Air conditioning (A/C) systems may generally be used in residential and/or commercial areas cooling to create comfortable temperatures inside those areas. Some A/C systems may generally be capable of cooling a comfort zone by transferring heat from a comfort zone to an ambient zone using a refrigeration cycle. To facilitate efficient and effective heat transfer in the heat pump system, refrigerant temperature management remains a critical part of the A/C system design. 
     SUMMARY 
     In some embodiments of the disclosure, an indoor unit of an air conditioning (A/C) system is disclosed as comprising a liquid/suction heat exchanger (LSHX) and a superheat sensor configured to monitor the amount of superheat in refrigerant exiting the LSHX. 
     In other embodiments of the disclosure, an air conditioning (A/C) system is disclosed as comprising: an outdoor unit; and an indoor unit, comprising: a liquid/suction heat exchanger (LSHX); and a superheat sensor configured to monitor the amount of superheat in refrigerant exiting the LSHX. 
     In yet other embodiments of the disclosure, a method of operating an air conditioning (A/C) system is disclosed as comprising: providing an A/C system comprising an outdoor unit and an indoor unit comprising an indoor metering device and a liquid/suction heat exchanger (LSHX); monitoring the amount of superheat in refrigerant exiting the LSHX; and adjusting a position of the indoor metering device to control the amount of superheat in the refrigerant exiting the LSHX. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description: 
         FIG. 1  is a schematic diagram of an air conditioning (A/C) system according to an embodiment of the disclosure; 
         FIG. 2  is a schematic diagram of an air conditioning (A/C) system according to another embodiment of the disclosure; 
         FIG. 3  is a flowchart of a method of operating an air conditioning (A/C) system according to an embodiment of the disclosure; and 
         FIG. 4  is a schematic diagram of a general-purpose processor according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , a schematic diagram of an air conditioning (A/C) system  100  is shown according to an embodiment of the disclosure. Most generally, A/C system  100  may be selectively operated to implement a closed thermodynamic refrigeration cycle to provide a cooling functionality (hereinafter, “cooling mode”). The A/C system  100  generally comprises an indoor unit  102 , an outdoor unit  104 , and a system controller  106  that may generally control operation of the indoor unit  102  and/or the outdoor unit  104 . 
     Indoor unit  102  generally comprises an indoor heat exchanger  108 , an indoor fan  110 , an indoor metering device  112 , and an indoor controller  124 . The indoor heat exchanger  108  may generally be configured to promote heat exchange between refrigerant carried within internal tubing of the indoor heat exchanger  108  and an airflow that may contact the indoor heat exchanger  108  but that is segregated from the refrigerant. In some embodiments, indoor heat exchanger  108  may comprise a plate-fin heat exchanger. However, in other embodiments, indoor heat exchanger  108  may comprise a spine fin heat exchanger, a microchannel heat exchanger, or any other suitable type of heat exchanger. 
     The indoor fan  110  may generally comprise a centrifugal blower comprising a blower housing, a blower impeller at least partially disposed within the blower housing, and a blower motor configured to selectively rotate the blower impeller. The indoor fan  110  may generally be configured to provide airflow through the indoor unit  102  and/or the indoor heat exchanger  108  to promote heat transfer between the airflow and a refrigerant flowing through the indoor heat exchanger  108 . The indoor fan  110  may also be configured to deliver temperature-conditioned air from the indoor unit  102  to one or more areas and/or zones of a climate controlled structure. The indoor fan  110  may generally comprise a centrifugal, mixed-flow fan and/or any other suitable type of fan. The indoor fan  110  may generally be configured as a modulating and/or variable speed fan capable of being operated at many speeds over one or more ranges of speeds. In other embodiments, the indoor fan  110  may be configured as a multiple speed fan capable of being operated at a plurality of operating speeds by selectively electrically powering different ones of multiple electromagnetic windings of a motor of the indoor fan  110 . In yet other embodiments, however, the indoor fan  110  may be a single speed fan. 
     The indoor metering device  112  may generally comprise an active expansion valve. More specifically, the indoor metering device  112  may comprise an electronically-controlled motor-driven electronic expansion valve (EEV). In some embodiments, however, the indoor metering device  112  may comprise a thermostatic expansion valve. In some embodiments, while the indoor metering device  112  may be configured to meter the volume and/or flow rate of refrigerant through the indoor metering device  112 , the indoor metering device  112  may also comprise and/or be associated with a refrigerant check valve and/or refrigerant bypass configuration when the direction of refrigerant flow through the indoor metering device  112  is such that the indoor metering device  112  is not intended to meter or otherwise substantially restrict flow of the refrigerant through the indoor metering device  112 . 
     Outdoor unit  104  generally comprises an outdoor heat exchanger  114 , a compressor  116 , an outdoor fan  118 , and an outdoor controller  126 . In some embodiments, the outdoor unit  104  may also comprise a plurality of temperature sensors for measuring the temperature of the outdoor heat exchanger  114 , the compressor  116 , and/or the outdoor ambient temperature. The outdoor heat exchanger  114  may generally be configured to promote heat transfer between a refrigerant carried within internal passages of the outdoor heat exchanger  114  and an airflow that contacts the outdoor heat exchanger  114  but that is segregated from the refrigerant. In some embodiments, outdoor heat exchanger  114  may comprise a plate-fin heat exchanger. However, in other embodiments, outdoor heat exchanger  114  may comprise a spine-fin heat exchanger, a microchannel heat exchanger, or any other suitable type of heat exchanger. 
     The compressor  116  may generally comprise a variable speed scroll-type compressor that may generally be configured to selectively pump refrigerant at a plurality of mass flow rates through the indoor unit  102 , the outdoor unit  104 , and/or between the indoor unit  102  and the outdoor unit  104 . In some embodiments, the compressor  116  may comprise a rotary type compressor configured to selectively pump refrigerant at a plurality of mass flow rates. In alternative embodiments, however, the compressor  116  may comprise a modulating compressor that is capable of operation over a plurality of speed ranges, a reciprocating-type compressor, a single speed compressor, and/or any other suitable refrigerant compressor and/or refrigerant pump. 
     The outdoor fan  118  may generally comprise an axial fan comprising a fan blade assembly and fan motor configured to selectively rotate the fan blade assembly. The outdoor fan  118  may generally be configured to provide airflow through the outdoor unit  104  and/or the outdoor heat exchanger  114  to promote heat transfer between the airflow and a refrigerant flowing through the indoor heat exchanger  108 . The outdoor fan  118  may generally be configured as a modulating and/or variable speed fan capable of being operated at a plurality of speeds over a plurality of speed ranges. In other embodiments, the outdoor fan  118  may comprise a mixed-flow fan, a centrifugal blower, and/or any other suitable type of fan and/or blower, such as a multiple speed fan capable of being operated at a plurality of operating speeds by selectively electrically powering different multiple electromagnetic windings of a motor of the outdoor fan  118 . In yet other embodiments, the outdoor fan  118  may be a single speed fan. Further, in other embodiments, however, the outdoor fan  118  may comprise a mixed-flow fan, a centrifugal blower, and/or any other suitable type of fan and/or blower. 
     The system controller  106  may generally be configured to selectively communicate with an indoor controller  124  of the indoor unit  102 , an outdoor controller  126  of the outdoor unit  104  and/or other components of the A/C system  100 . In some embodiments, the system controller  106  may be configured to control operation of the indoor unit  102  and/or the outdoor unit  104 . In some embodiments, the system controller  106  may be configured to monitor and/or communicate with a plurality of temperature sensors associated with components of the indoor unit  102 , the outdoor unit  104 , and/or the ambient outdoor temperature. Additionally, in some embodiments, the system controller  106  may comprise a temperature sensor and/or may further be configured to control heating and/or cooling of zones associated with the A/C system  100 . In other embodiments, however, the system controller  106  may be configured as a thermostat for controlling the supply of conditioned air to zones associated with the A/C system  100 . 
     The system controller  106  may also generally comprise a touchscreen interface for displaying information and for receiving user inputs. The system controller  106  may display information related to the operation of the A/C system  100  and may receive user inputs related to operation of the A/C system  100 . However, the system controller  106  may further be operable to display information and receive user inputs tangentially and/or unrelated to operation of the A/C system  100 . In some embodiments, however, the system controller  106  may not comprise a display and may derive all information from inputs from remote sensors and remote configuration tools. 
     The indoor controller  124  may be carried by the indoor unit  102  and may generally be configured to receive information inputs, transmit information outputs, and/or otherwise communicate with the system controller  106 , the outdoor controller  126 , and/or any other device via any suitable medium of communication. In some embodiments, the indoor controller  124  may be configured to receive information related to a speed of the indoor fan  110 , transmit a control output to an electric heat relay, transmit information regarding an indoor fan  110  volumetric flow-rate, and communicate with an indoor EEV controller  128  configured to control operation of the indoor metering device  112 . In some embodiments, the indoor controller  124  may be configured to communicate with an indoor fan controller and/or otherwise affect control over operation of the indoor fan  110 . 
     The indoor EEV controller  128  may be configured to receive information regarding temperatures and/or pressures of the refrigerant in the indoor unit  102 . More specifically, the indoor EEV controller  128  may be configured to receive information regarding temperatures and pressures of refrigerant entering, exiting, and/or within the indoor heat exchanger  108 . Further, the indoor EEV controller  128  may be configured to communicate with the indoor metering device  112  and/or otherwise affect control over the indoor metering device  112 . 
     The outdoor controller  126  may be carried by the outdoor unit  104  and may be configured to receive information inputs, transmit information outputs, and/or otherwise communicate with the system controller  106 , the indoor controller  124 , and/or any other device via any suitable medium of communication. In some embodiments, the outdoor controller  126  may be configured to receive information related to an ambient temperature associated with the outdoor unit  104 , information related to a temperature of the outdoor heat exchanger  114 , and/or information related to refrigerant temperatures and/or pressures of refrigerant entering, exiting, and/or within the outdoor heat exchanger  114  and/or the compressor  116 . In some embodiments, the outdoor controller  126  may be configured to transmit information related to monitoring, communicating with, and/or otherwise affecting control over the compressor  116 , the outdoor fan  118 , a relay associated with adjusting and/or monitoring a refrigerant charge of the A/C system  100 , and/or a position of the indoor metering device  112 . The outdoor controller  126  may further be configured to communicate with and/or control a compressor drive controller that is configured to electrically power and/or control the compressor  116 . 
     The A/C system  100  is shown configured for operating in the cooling mode in which heat is absorbed by refrigerant at the indoor heat exchanger  108  and heat is rejected from the refrigerant at the outdoor heat exchanger  114 . In some embodiments, the compressor  116  may be operated to compress refrigerant and pump the relatively high temperature and high pressure compressed refrigerant from the compressor  116  to the outdoor heat exchanger  114 . As the refrigerant is passed through the outdoor heat exchanger  114 , the outdoor fan  118  may be operated to move air into contact with the outdoor heat exchanger  114 , thereby transferring heat from the refrigerant to the air surrounding the outdoor heat exchanger  114  (condenser in cooling mode). The refrigerant may primarily comprise liquid phase refrigerant and the refrigerant may flow from the outdoor heat exchanger  114  to the indoor metering device  112 . The indoor metering device  112  may meter passage of the refrigerant through the indoor metering device  112  so that the refrigerant downstream of the indoor metering device  112  is at a lower pressure than the refrigerant upstream of the indoor metering device  112 . The pressure differential across the indoor metering device  112  allows the refrigerant downstream of the indoor metering device  112  to expand and/or at least partially convert to a two-phase (vapor and gas) mixture. The two phase refrigerant may enter the indoor heat exchanger  108  (evaporator in cooling mode). As the refrigerant is passed through the indoor heat exchanger  108 , the indoor fan  110  may be operated to move air into contact with the indoor heat exchanger  108 , thereby transferring heat to the refrigerant from the air surrounding the indoor heat exchanger  108 , and causing evaporation of the liquid portion of the two phase mixture. The refrigerant may thereafter re-enter the compressor  116 . 
     Referring now to  FIG. 2 , an A/C system  200  is shown according to another embodiment of the disclosure. A/C system  200  may generally be substantially similar to A/C system  100  and comprise outdoor unit  104  and system controller  106 . A/C system  200  also comprises an indoor unit  202  that is substantially similar to indoor unit  102 . However, indoor unit  202  comprises a Liquid/Suction Heat Exchanger (LSHX)  230  and a superheat sensor  240 . Generally, the LSHX  230  may be coupled between the outdoor heat exchanger  114  and the indoor metering device  112  on a so-called “liquid” line. Additionally, the LSHX  230  may be coupled between the indoor heat exchanger  108  and the compressor  116  on a so-called “vapor” line. The LSHX  230  may generally be configured to increase the efficiency of the A/C system  200  by providing optimal system subcooling and/or superheat in the refrigerant of the A/C system  200  as compared to A/C system  100  that does not include an LSHX  230  and must accomplish said subcooling and superheat in the outdoor and indoor heat exchangers, respectively. Subcooling refers to the number of degrees that liquid refrigerant is below the refrigerant saturation temperature (when condenses to a liquid), while superheat refers to the number of degrees that vapor refrigerant is above the refrigerant saturation temperature. 
     The superheat sensor  240  may generally be disposed on the so-called suction line at a location downstream from the LSHX  230  and configured to measure the temperature and/or the pressure of the refrigerant exiting the LSHX  230 . In alternative embodiments, the superheat sensor  240  may be disposed upstream of the LSHX  230  between the LSHX  230  and the indoor heat exchanger  108  and configured to measure and/or monitor the temperature and/or the pressure of the refrigerant entering the LSHX  230 . Generally, the indoor controller  124  may be configured to monitor the temperature of the vapor refrigerant exiting the LSHX  230  via the superheat sensor  240  and communicate with the indoor EEV controller  128  to control the position of and/or operation of the indoor metering device  112 . By monitoring the superheat sensor  240  and controlling the indoor metering device  112 , the indoor controller  124  may control the amount of superheat in the refrigerant exiting the indoor heat exchanger  108  and/or exiting the LSHX  230 . Alternatively, the temperature of the vapor refrigerant leaving the LSHX  230  could be monitored with a sensing bulb of a thermostatic expansion valve, the superheat thereby being controlled by the thermostatic expansion valve. 
     When the A/C system  200  is operated in the cooling mode, the LSHX  230  may receive subcooled refrigerant from the outdoor heat exchanger  114 . Generally, the amount of subcooling in the refrigerant entering the LSHX  230  may be at least about 1 degree Fahrenheit. However, in other embodiments, the amount of subcooling in the refrigerant received by the LSHX  230  may be at least about 2 degrees Fahrenheit, at least about 3 degrees Fahrenheit, at least about 5 degrees Fahrenheit, at least about 7 degrees Fahrenheit, and/or at least about 10 degrees Fahrenheit. The subcooled refrigerant may pass through the LSHX  230  and be further cooled within the LSHX  230 . Accordingly, the LSHX  230  may be configured to further increase the amount of subcooling within the refrigerant passing though the LSHX  230 . In some embodiments, the LSHX  230  may increase the amount of subcooling to at least about 2 degrees Fahrenheit, at least about 3 degrees Fahrenheit, at least about 5 degrees Fahrenheit, at least about 7 degrees Fahrenheit, at least about 10 degrees Fahrenheit, and/or at least about 12 degrees Fahrenheit. Because some of the subcooling is performed by the LSHX  230 , the outdoor heat exchanger  114  may transfer heat more efficiently and/or effectively, thereby increasing the efficiency of the A/C system  200 . 
     The LSHX  230  receives refrigerant that exits the indoor heat exchanger  108  after having passed through the indoor heat exchanger  108 . In some embodiments, refrigerant leaving the indoor heat exchanger  108  may be superheated by at least about 1 degree Fahrenheit. However, in other embodiments, the refrigerant leaving the indoor heat exchanger  108  may comprise a superheat of at least about 2 degrees Fahrenheit, at least about 3 degrees Fahrenheit, at least about 5 degrees Fahrenheit, at least about 7 degrees Fahrenheit, and/or at least about 10 degrees Fahrenheit. The superheated refrigerant may pass through the LSHX  230  and be further superheated within the LSHX  230 . Accordingly, the LSHX  230  may be configured to further increase the amount of superheat within the refrigerant passing though the LSHX  230 . In some embodiments, the LSHX  230  may increase the amount of superheat to at least about 2 degrees Fahrenheit, at least about 3 degrees Fahrenheit, at least about 5 degrees Fahrenheit, at least about 7 degrees Fahrenheit, at least about 10 degrees Fahrenheit, and/or at least about 12 degrees Fahrenheit. Because the majority of the superheat is performed by the LSHX  230 , the indoor heat exchanger  108  may transfer heat more efficiently and/or effectively, thereby increasing the efficiency of the A/C system  200 . 
     After the refrigerant is further superheated within the LSHX  230 , the superheated refrigerant may exit the LSHX  230 . The superheat sensor  240  may continuously monitor the temperature and/or the pressure of the superheated refrigerant exiting the LSHX  230 . Generally, the position of the indoor metering device  112  may be controlled by the indoor EEV controller  128  in response to the superheat sensor  240  communicating the temperature and/or pressure of the superheated refrigerant exiting the LSHX  230  to the indoor controller  124 . To increase the superheat in the refrigerant exiting the LSHX  230 , the indoor metering device  112  may be adjusted to reduce the pressure of the refrigerant exiting the indoor metering device  112  and entering the indoor heat exchanger  108 . Alternatively, to reduce the superheat in the refrigerant exiting the LSHX  230 , the indoor metering device  112  may be adjusted to increase the pressure of the refrigerant exiting the indoor metering device  112  and entering the indoor heat exchanger  108 . Accordingly, the position of the indoor metering device  112  may be continuously adjusted to maintain a specified and/or predetermined amount of superheat in the refrigerant leaving the LSHX  230 . 
     From the LSHX  230 , superheated refrigerant may then exit the indoor unit  202  and enter the outdoor unit  104 , where it may then pass to the compressor  116 . Since the refrigerant entering the compressor  116  is superheated, substantially no liquid-phase refrigerant may pass to the compressor  116 . As such, substantially all of the refrigerant that passes to the compressor  116  may be in a superheated, vapor phase. Because liquid refrigerant may cause damage to the compressor  116 , the LSHX  230  prevents liquid-phase refrigerant from entering the compressor  116  by superheating the refrigerant that passes through the LSHX  230 . 
     Additionally, after refrigerant has been compressed by the compressor  116  and passed through the outdoor heat exchanger  114 , the refrigerant may be passed from the outdoor heat exchanger  114  to the LSHX  230  through liquid line  250 . In some embodiments, liquid line  250  may be about 30 feet long. Because much of the subcooling is performed by the LSHX  230  as opposed to the outdoor heat exchanger  114  as in A/C system  100 , refrigerant in the liquid line  250  may be about 5 to about 6 degrees Fahrenheit warmer than in a liquid line of A/C system  100 . Accordingly, the liquid line  250  may promote heat transfer between the refrigerant in the liquid line  250  and the surrounding ambient environment, thereby further increasing the efficiency of the AC system  200 . 
     The LSHX  230  may generally be configured to increase the efficiency of the A/C system  200  by reducing the amount of subcooling in the refrigerant leaving the outdoor heat exchanger  118  (condenser) and reducing the amount of superheat in the refrigerant leaving the indoor heat exchanger  114  (evaporator). In order to effectively boost the efficiency of the A/C system  200 , refrigerant entering the LSHX  230  in the liquid line must always be at least slightly subcooled, and refrigerant entering the LSHX  230  on the vapor line must always be at least slightly superheated. If two-phase refrigerant enters either side of the LSHX  230 , excessive heat exchange may occur in LSHX  230  and degrade efficiency of the LSHX  230  and/or the A/C system  200 . Additionally, two-phase refrigerant entering the LSHX  230  may also cause the indoor metering device  112  to operate unstably, thereby making it difficult to control the superheat through the superheat sensor  240 . 
     The LSHX  230  may effectively boost the efficiency of the A/C system  200  by at least about 5% as compared to A/C system  100 . However, in some embodiments, the LSHX  230  may provide an increase in efficiency of at least about 10% as compared to A/C system  100 . For example, if A/C system  100  comprises a 25 Seasonal Energy Efficiency Ratio (SEER) rating, A/C system  200  may comprise a 27.5 Seasonal Energy Efficiency Ratio (SEER) rating. In part, the increase in efficiency may be attributed to the LSHX  230  providing at least about 5 degrees Fahrenheit less subcooling leaving the outdoor heat exchanger  118  (condenser) and/or at least about 10 degrees less superheat leaving the indoor heat exchanger  114  (evaporator) as compared to A/C system  100  while the subcooling entering the indoor metering device  112  and the superheat entering compressor  116  remain substantially the same. However, in some embodiments, the LSHX  230  may provide at least about 10 degrees Fahrenheit more subcooling and/or at least about 10 degrees more superheat as compared to A/C system  100 . In other embodiments, the LSHX  230  may provide at least about 15 degrees Fahrenheit more subcooling and/or at least about 15 degrees more superheat as compared to A/C system  100 . 
     It will be appreciated that although the LSHX  230  is depicted as being installed in an air conditioning (A/C) system  200 , the LSHX  230  may also be configured to be installed in the indoor unit of a reversible heating, ventilation and/or air conditioning (HVAC) heat pump system. When the HVAC heat pump system is operated in a cooling mode, the LSHX  230  and/or the superheat sensor  240  would operate substantially similar to A/C system  200 . However, it will be appreciated that the HVAC system may comprise a reversing valve installed in the outdoor unit  124  that is configured to reverse the flow of refrigerant through the HVAC heat pump system. Thus, when the HVAC heat pump system is operated in a heating mode, the flow of refrigerant through the HVAC heat pump system will be reversed as compared to the flow of refrigerant in the cooling mode. Accordingly, the HVAC heat pump system may comprise a plurality of check valves, solenoid valves, and/or any other suitable configuration of valves that would effectively remove the LSHX  230  from the fluid circuit during operation in the heating mode. As such, any configuration of electronic solenoids and/or electrically controlled valves may be controlled by the system controller  106 , the indoor controller  124 , and/or the outdoor controller  126  to remove the LSHX  230  from the fluid circuit. Additionally, the HVAC heat pump may also comprise a bypass line and/or a plurality of bypass lines that operate in conjunction with the valves to remove the LSHX  230  from the fluid circuit when the HVAC heat pump system is operated in the heating mode. 
     Referring now to  FIG. 3 , a flowchart of a method  300  of operating an A/C system  200  is shown according to an embodiment of the disclosure. The method  300  may begin at block  302  by providing an A/C system  200  comprising a Liquid/Suction Heat exchanger (LSHX)  230  in an indoor unit  202  of the A/C system  200 . Generally, the LSHX  230  may be coupled between an outdoor heat exchanger, such as outdoor heat exchanger  118 , and an indoor metering device, such as indoor metering device  112 , on a so-called “liquid” line. Additionally, the LSHX  230  may be coupled between an indoor heat exchanger, such as indoor heat exchanger  108 , and a compressor, such as compressor  116 , on a so-called “vapor” line. The method  300  may continue at block  304  by operating the A/C system  200  in a cooling mode. The method may continue at block  306  by increasing the amount of subcooling in the refrigerant by passing the refrigerant through a liquid line of the LSHX  230 . The method  300  may continue at block  308  by passing the higher subcooled refrigerant through an expansion device  112  and an indoor heat exchanger  108 . The method may continue at block  310  by increasing the amount of superheat in the refrigerant by passing the refrigerant through a vapor line of the LSHX  230 . The method may continue at block  312  by monitoring the amount of superheat in the higher superheated refrigerant exiting the LSHX  230 . The method  300  may conclude at block  314  by controlling the position of the indoor metering device  112  in response to monitoring the amount of superheat in the higher superheated refrigerant exiting the LSHX  230  to control the amount of superheat in the refrigerant exiting the LSHX  230 . In some embodiments, the temperature of the superheated refrigerant may be monitored via a superheat sensor  240  disposed downstream of the LSHX  230 . In alternative embodiments, the temperature of the superheated refrigerant may be monitored via a superheat sensor  240  disposed upstream of the LSHX  230  and downstream from the indoor heat exchanger  108 . 
     Referring now to  FIG. 4 , a schematic diagram of a general-purpose processing (e.g., electronic controller or computer) system  1300  is shown according to an embodiment of the disclosure. In some embodiments, processing system  1300  may be system controller  106 , indoor controller  124 , and/or outdoor controller  126  and be suitable for implementing one or more embodiments disclosed herein. In addition to the processor  1310  (which may be referred to as a central processor unit or CPU), the system  1300  may comprise network connectivity devices  1320 , random access memory (RAM)  1330 , read only memory (ROM)  1340 , secondary storage  1350 , and input/output (I/O) devices  1360 . In some cases, some of these components may not be present or may be combined in various combinations with one another or with other components not shown. These components may be located in a single physical entity or in more than one physical entity. Any actions described herein as being taken by the processor  1310  might be taken by the processor  1310  alone or by the processor  1310  in conjunction with one or more components of the processor system  1300 . 
     The processor  1310  generally executes algorithms, instructions, codes, computer programs, and/or scripts that it might access from the network connectivity devices  1320 , RAM  1330 , ROM  1340 , or secondary storage  1350  (which might include various disk-based systems such as hard disk, floppy disk, optical disk, or other drive). While only one processor  1310  is shown, processor system  1300  may comprise multiple processors  1310 . Thus, while instructions may be discussed as being executed by a processor  1310 , the instructions may be executed simultaneously, serially, or otherwise by one or multiple processors  1310 . The processor  1310  may be implemented as one or more CPU chips. 
     The network connectivity devices  1320  may take the form of modems, modem banks, Ethernet devices, universal serial bus (USB) interface devices, serial interfaces, token ring devices, fiber distributed data interface (FDDI) devices, wireless local area network (WLAN) devices, radio transceiver devices such as code division multiple access (CDMA) devices, global system for mobile communications (GSM) radio transceiver devices, worldwide interoperability for microwave access (WiMAX) devices, Bluetooth, CAN (Controller Area Network) and/or other well-known technologies, protocols and standards for connecting to networks. These network connectivity devices  1320  may enable the processor  1310  to communicate with the Internet or one or more telecommunications networks or other networks from which the processor  1310  might receive information or to which the processor  1310  might output information. 
     The network connectivity devices  1320  might also include one or more transceiver components  1325  capable of transmitting and/or receiving data wirelessly in the form of electromagnetic waves, such as radio frequency signals or microwave frequency signals. Alternatively, the data may propagate in or on the surface of electrical conductors, in coaxial cables, in waveguides, in optical media such as optical fiber, or in other media. The transceiver component  1325  might include separate receiving and transmitting units or a single transceiver. Information transmitted or received by the transceiver component  1325  may include data that has been processed by the processor  1310  or instructions that are to be executed by processor  1310 . Such information may be received from and outputted to a network in the form, for example, of a computer data baseband signal or signal embodied in a carrier wave. The data may be ordered according to different sequences as may be desirable for either processing or generating the data or transmitting or receiving the data. The baseband signal, the signal embedded in the carrier wave, or other types of signals currently used or hereafter developed may be referred to as the transmission medium and may be generated according to several methods well-known to one skilled in the art. 
     The RAM  1330  might be used to store volatile data and perhaps to store instructions that are executed by the processor  1310 . The ROM  1340  is a non-volatile memory device that typically has a smaller memory capacity than the memory capacity of the secondary storage  1350 . ROM  1340  might be used to store instructions and perhaps data that are read during execution of the instructions. Access to both RAM  1330  and ROM  1340  is typically faster than access to secondary storage  1350 . The secondary storage  1350  is typically comprised of one or more disk drives or tape drives and might be used for non-volatile storage of data or as an over-flow data storage device if RAM  1330  is not large enough to hold all working data. Secondary storage  1350  may be used to store programs or instructions that are loaded into RAM  1330  when such programs are selected for execution or information is needed. 
     The I/O devices  1360  may include liquid crystal displays (LCDs), touch screen displays, keyboards, keypads, switches, dials, mice, track balls, voice recognizers, card readers, paper tape readers, printers, video monitors, transducers, sensors, or other well-known input or output devices. Also, the transceiver component  1325  might be considered to be a component of the I/O devices  1360  instead of or in addition to being a component of the network connectivity devices  1320 . Some or all of the I/O devices  1360  may be substantially similar to various components disclosed herein. 
     At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R 1 , and an upper limit, R u , is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R 1 +k*(R u −R 1 ), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Unless otherwise stated, the term “about” shall mean plus or minus 10 percent of the subsequent value. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present invention.