CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from and the benefit of U.S. Provisional Application Serial No. 62/611,412, entitled “SYSTEMS AND METHODS FOR PURGING A CHILLER SYSTEM,” filed December 28, 2017, which is herein incorporated by reference in its entirety for all purposes.

BACKGROUND

[0002] This application relates generally to purging systems for chiller systems.

[0003] Chiller systems, or vapor compression systems, utilize a working fluid, typically referred to as a refrigerant that changes phases between vapor, liquid, and combinations thereof in response to being subjected to different temperatures and pressures associated with operation of the vapor compression system. In low-pressure chiller systems, some components of the low-pressure chiller systems operate at a lower pressure than the surrounding atmosphere. Due to the pressure differential, non-condensable gases (NCG) such as ambient air may migrate into these low-pressure components, which may cause inefficiencies in the low-pressure chiller system. Accordingly, the low-pressure chiller system may be purged of the NCG to run more effectively. However, traditional purge systems used to remove the NCG may utilize additional refrigerant with medium or high global warming potential (GWP).

SUMMARY

[0004] In an embodiment of the present disclosure, a heating, ventilation, and air conditioning (HVAC) system includes a refrigerant loop configured to flow a refrigerant and a purge system configured to purge the HVAC system of non-condensable gases (NCG). The purge system includes a purge heat exchanger configured to receive a mixture of the NCG and the refrigerant. The purge heat exchanger is configured to separate the NCG of the mixture from the refrigerant of the mixture utilizing a non- refrigerant fluid. The purge system also includes a thermoelectric assembly configured to remove heat from the non-refrigerant fluid.

[0005] In another embodiment of the present disclosure, a heating, ventilation, and air conditioning (HVAC) system includes a refrigerant loop, a compressor disposed along the refrigerant loop and configured to circulate refrigerant through the refrigerant loop, an evaporator disposed along the refrigerant loop and configured to place the refrigerant in a heat exchange relationship with a first cooling fluid, a condenser disposed along the refrigerant loop and configured to place the refrigerant in a heat exchange relationship with a second cooling fluid, and a purge system configured to purge the HVAC system of non-condensable gases (NCG). The purge system includes a purge heat exchanger configured to separate a mixture drawn from the condenser utilizing a first refrigerant flow of the refrigerant drawn from the evaporator and utilizing a non-refrigerant fluid. The mixture includes the NCG and a second refrigerant flow of the refrigerant drawn from the condenser. The purge heat exchanger is configured to separate the NCG of the mixture from the second refrigerant flow of the mixture. The purge system also includes thermoelectric assemblies configured to remove thermal energy from the first refrigerant flow and the non-refrigerant fluid.

[0006] In another embodiment of the present disclosure, a heating, ventilation, and air conditioning (HVAC) system includes a refrigerant loop, a compressor disposed along the refrigerant loop and configured to circulate refrigerant through the refrigerant loop, an evaporator disposed along the refrigerant loop and configured to place the refrigerant in a heat exchange relationship with a first cooling fluid, a condenser disposed along the refrigerant loop and configured to place the refrigerant in a heat exchange relationship with second cooling fluid, and a purge system configured to purge the HVAC system of non-condensable gases (NCG). The purge system includes a purge heat exchanger configured to receive a mixture of the NCG and the refrigerant. The purge heat exchanger is configured to separate the NCG of the mixture from the refrigerant of the mixture utilizing a chilled fluid of a chilled fluid loop. The purge system also includes a thermoelectric assembly configured to chill the chilled fluid in conjunction with an intermediate fluid of an open fluid loop. BRIEF DESCRIPTION OF THE FIGURES

[0007] FIG. 1 is a perspective view of an embodiment of a building that may utilize a heating, ventilation, and air conditioning, (HVAC) system in a commercial setting, in accordance with an aspect of the present disclosure;

[0008] FIG. 2 is a perspective view of an embodiment of an HVAC system, in accordance with an aspect of the present disclosure;

[0009] FIG. 3 is a schematic of an embodiment of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure;

[0010] FIG. 4 is a schematic of an embodiment of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure;

[0011] FIG. 5 is a schematic of a thermoelectric assembly of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure;

[0012] FIG. 6 is a schematic of a thermoelectric assembly of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure.

[0013] FIG. 7 is a schematic of an embodiment of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure;

[0014] FIG. 8 is a schematic of an embodiment of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure;

[0015] FIG. 9 is a schematic of an embodiment of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure;

[0016] FIG. 10 is a schematic of an embodiment of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure;

[0017] FIG. 11 is a schematic of an embodiment of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure; [0018] FIG. 12 is a schematic of an embodiment of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure;

[0019] FIG. 13 is a schematic of an embodiment of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure;

[0020] FIG. 14 is a schematic of an embodiment of a heat exchanger of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure; and

[0021] FIG. 15 is a schematic of an embodiment of a heat exchanger of the HVAC system of FIG. 2, in accordance with an aspect of the present disclosure.

DETAILED DESCRIPTION

[0022] Embodiments of the present disclosure include a purge system that may improve an efficiency of purging in a heating, ventilation, and air conditioning (HVAC) system. For example, in certain low-pressure HVAC systems an evaporator may draw in non condensable gases (NCG) such as ambient air from the atmosphere due to a pressure differential between the evaporator and the atmosphere. The NCG may travel through the HVAC system to ultimately collect within the condenser. These NCG may be detrimental to the overall performance of the HVAC system, and as such, should be removed. Accordingly, the presently-disclosed embodiments may efficiently purge the HVAC system of the NCG via the purge system. For example, the purge system may pull a mixture of the NCG and refrigerant from the condenser. The purge system may then utilize a purge heat exchanger (e.g., a purge coil in a purge chamber) to decrease a temperature of, or remove heat from, the mixture to condense the refrigerant, thereby separating the refrigerant from the NCG due to the increase in density of the refrigerant as a byproduct of the refrigerant condensing. Particularly, the purge system may run a chilled fluid through the purge coil of the heat exchanger to condense the refrigerant and separate the mixture. In certain embodiments, the chilled fluid may be chilled via one or more thermoelectric assemblies. Further, in certain embodiments, the chilled fluid may also be chilled via a secondary chilled fluid that was also chilled via thermoelectric assemblies. In some embodiments, the purge heat exchanger may include two separate purge coils that may chill the mixture with separate chilled fluids.

[0023] Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, and air conditioning (HVAC) system 10 in a building 12 for a typical commercial setting. The HVAC system 10 may include a vapor compression system 14 that supplies a chilled liquid, which may be used to cool the building 12. The HVAC system 10 may also include a boiler 16 to supply warm liquid to heat the building 12 and an air distribution system which circulates air through the building 12. The air distribution system can also include an air return duct 18, an air supply duct 20, and/or an air handler 22. In some embodiments, the air handler 22 may include a heat exchanger that is connected to the boiler 16 and the vapor compression system 14 by conduits 24. The heat exchanger in the air handler 22 may receive either heated liquid from the boiler 16 or chilled liquid from the vapor compression system 14, depending on the mode of operation of the HVAC system 10. The HVAC system 10 is shown with a separate air handler on each floor of building 12, but in other embodiments, the HVAC system 10 may include air handlers 22 and/or other components that may be shared between or among floors.

[0024] FIGS. 2 and 3 are embodiments of the vapor compression system 14 that can be used in the HVAC system 10. The vapor compression system 14 may circulate a refrigerant through a circuit starting with a compressor 32. The circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and a liquid chiller or an evaporator 38. The vapor compression system 14 may further include a control panel 40 (e.g., controller) that has an analog to digital (A/D) converter 42, a microprocessor 44, a non volatile memory 46, and/or an interface board 48.

[0025] Some examples of fluids that may be used as refrigerants in the vapor compression system 14 are hydrofluorocarbon (HFC) based refrigerants, for example, R- 410A, R-407, R-l34a, hydrofluoro-olefin (HFO),“natural” refrigerants like ammonia (NH ₃ ), R-717, carbon dioxide (CO2), R-744, or hydrocarbon based refrigerants, water vapor, refrigerants with low global warming potential (GWP), or any other suitable refrigerant. In some embodiments, the vapor compression system 14 may be configured to efficiently utilize refrigerants having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit or less) at one atmosphere of pressure, also referred to as low pressure refrigerants, versus a medium pressure refrigerant, such as R-l34a. As used herein,“normal boiling point” may refer to a boiling point temperature measured at one atmosphere of pressure.

[0026] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSDs) 52, a motor 50, the compressor 32, the condenser 34, the expansion valve or device 36, and/or the evaporator 38. The motor 50 may drive the compressor 32 and may be powered by a variable speed drive (VSD) 52. The VSD 52 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 may be powered directly from an AC or direct current (DC) power source. The motor 50 may include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

[0027] The compressor 32 compresses a refrigerant vapor and delivers the vapor to the condenser 34 through a discharge passage. In some embodiments, the compressor 32 may be a centrifugal compressor. The refrigerant vapor pumped by the compressor 32 to the condenser 34 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34. The refrigerant vapor may condense to a refrigerant liquid in the condenser 34 as a result of thermal heat transfer with the cooling fluid. The refrigerant liquid from the condenser 34 may flow through the expansion device 36, for the purposes of reducing the temperature and pressure of the refrigerant liquid, to the evaporator 38. In the illustrated embodiment of FIG. 3, the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies the cooling fluid to the condenser.

[0028] The refrigerant liquid delivered to the evaporator 38 may absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in the condenser 34. The refrigerant liquid in the evaporator 38 may undergo a phase change from the refrigerant liquid to a refrigerant vapor. As shown in the illustrated embodiment of FIG. 3, the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to a cooling load 62. The cooling fluid of the evaporator 38 (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 38 via return line 60R and exits the evaporator 38 via supply line 60S. The evaporator 38 may reduce the temperature of the cooling fluid in the tube bundle 58 via thermal heat transfer with the refrigerant. The tube bundle 58 in the evaporator 38 can include a plurality of tubes and/or a plurality of tube bundles. In any case, the refrigerant vapor exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.

[0029] FIG. 4 is a schematic of the vapor compression system 14 with an intermediate circuit 64 incorporated between condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly coupled to the condenser 34. As shown in the illustrated embodiment of FIG. 4, the inlet line 68 includes a first expansion device 66 positioned upstream of an intermediate vessel 70. In some embodiments, the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate vessel 70 may be configured as a heat exchanger or a "surface economizer." In the illustrated embodiment of FIG. 4, the intermediate vessel 70 is used as a flash tank, and the first expansion device 66 is configured to lower the pressure of (e.g., expand) the refrigerant liquid received from the condenser 34. During the expansion process, a portion of the liquid may vaporize, and thus, the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66. Additionally, the intermediate vessel 70 may provide for further expansion of the refrigerant liquid because of a pressure drop experienced by the refrigerant liquid when entering the intermediate vessel 70 (e.g., due to a rapid increase in volume experienced when entering the intermediate vessel 70). The vapor in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32, or through a centrifugal compressor. In other embodiments, the vapor in the intermediate vessel may be drawn to an intermediate stage of the compressor 32 (e.g., not the suction stage). The liquid that collects in the intermediate vessel 70 may be at a lower enthalpy than the refrigerant liquid exiting the condenser 34 because of the expansion in the expansion device 66 and/or the intermediate vessel 70. The liquid from intermediate vessel 70 may then flow in line 72 through a second expansion device 36 to the evaporator 38.

[0030] In some embodiments, when the vapor compression system 14 is in operation, the evaporator 38 may function at a pressure that is lower than the ambient pressure. As such, NCG may be drawn into the evaporator 38 and move through the compressor 32 to gather in the condenser 34. These NCG may cause the vapor compression system 14 to operate inefficiently because the NCG may act as insulators preventing effective heat transfer from the refrigerant to the cooling fluid (e.g., water or air) within the condenser 34. Accordingly, the vapor compression system 14 may include features to purge the vapor compression system 14 of the NCG.

[0031] Particularly, the vapor compression system 14 may include a purge system 80 to purge the vapor compression system 14 of NCG. As mentioned above, the purge system 80 may purge the vapor compression system 14 at least in part by reducing a temperature of, or removing heat from, a mixture of NCG and refrigerant vapor that is pulled from the condenser 34, thereby condensing the refrigerant vapor and separating the refrigerant from the NCG. Specifically, the purge system 80 may remove heat from the mixture via a chilled fluid, which may become chilled through utilization of one or more thermoelectric assemblies 82, as shown in FIGS. 5 and 6. Each thermoelectric assembly 82 may include a set of conductive plates, such as a hot side 84 and a cold side 86, and a thermoelectric device 88, such as a set of semiconductors. The conductive plates may be coupled to the thermoelectric device 88 via thermal paste. The thermoelectric device 88 may include a set of extrinsic, doped semiconductors with an electric imbalance, such as positive (P-type) or negative (N-type) semiconductors, which may carry positive or negative charges, respectively. For example, heat may be absorbed through the cold side 86, transferred through the thermoelectric device 88, and released through the hot side 84. Indeed, the thermoelectric assembly 82 may create a temperature difference, or a thermal gradient, between the cold side 86 and the hot side 84, from an electrical energy difference. Further, higher temperature differences may decrease the heat removal capability of the thermoelectric assembly 82, while smaller temperature differences may increase the heat removal capability of the thermoelectric assembly 82. Each thermoelectric assembly 82 may utilize a power source 90 to induce an electrical power gradient within the thermoelectric assembly 82. The power source 90 may be any suitable power source, such as a power grid, a battery, a solar panel, an electrical generator, a gas engine, the vapor compression system 14, or any combination thereof. The thermoelectric assembly 82 may convert the electrical power gradient to a thermal gradient through a thermoelectric effect, or Peltier-Seebeck effect.

[0032] The thermoelectric assemblies 82 may utilize the thermal gradient to absorb heat from fluid 92 flowing and/or disposed within a conduit 94. The cold side 86 of the thermoelectric assembly 82 may be coupled to the conduit 94 via a heat sink 96 and/or heat paste 98, which may conduct, or transfer, heat from the fluid 92 to the thermoelectric device 88, thereby chilling the fluid 92 within the conduit 94. Further, the hot side 84 of the thermoelectric assembly 82 may be coupled to another heat sink 96, which may be configured to remove heat from the hot side 84. To this end, the thermoelectric assembly 82 may also include a fan 100 configured to draw ambient air 102 in through sides of the heat sink 96 and expel heated ambient air 102 to the surroundings. In this manner, the ambient air 102 may remove heat from the heat sink 96 as the fan 100 draws the ambient air 102 in through the heat sink 96 and forces the ambient air 102 in the form of heated air out of the thermoelectric assembly 82 with an increase in temperature.

[0033] As discussed herein, in some embodiments, the hot side 84 of the thermoelectric assembly 82 may additionally, or in the alternative, be coupled to another conduit 94 with another fluid 92, which may also be chilled some amount and configured to remove heat from the hot side 84. In this manner, a temperature of the cold side 86 may be reduced due to the fact that the hot side 84 may be chilled to some temperature below a temperature of the ambient air 102. Indeed, due at least in part to the reduced temperatures and temperature differential of the cold side 86 and the hot side 84, the heat- removal capabilities of the thermoelectric assembly 82 may be increased. Further still, in some embodiments the thermoelectric assembly 82 may include more than one set of the cold side 86, the thermoelectric device 88, and the hot side 84. For example, the conduit 94 may be coupled to a first cold side 86, which is coupled to a first hot side 84 via a first thermoelectric device 88. The first hot side 84 may additionally be coupled to a second cold side 86, which is in turn coupled to a second hot side 84 via a second thermoelectric device 88. The second hot side 84 may then be coupled to any suitable heat-removing system, such as heat sinks 96, fans 100, and/or conduits 94 as discussed above. Indeed, there may be any suitable number of sets of the cold side 86, the thermoelectric device 88, and the hot side 84 stacked within the thermoelectric assembly 82.

[0034] As illustrated in FIGS. 7-13, the vapor compression system 14 may include the purge system 80, which is configured to remove NCG, such as ambient air, from the vapor compression system 14. To this end, the purge system 80 may include one or more thermoelectric assemblies 82, one or more pumps 110, such as vacuum pumps, liquid pumps, and/or compressors one or more stop valves 112, and a purge heat exchanger 114. The purge heat exchanger 114 may further include one or more purge coils 116 in a purge chamber 118. Further, it should be noted that the conduits discussed in FIGS. 7-13 may be similar to the conduit 94 of FIGS. 5 and 6.

[0035] Further, the vapor compression system 14 may utilize a controller 120 to control certain aspects of operation of the purge system 80. The controller 120 may be any device employing a processor 122 (which may represent one or more processors), such as an application-specific processor. The controller 120 may also include a memory device 124 for storing instructions executable by the processor 122 to perform the methods and control actions described herein for the purge system 80. The processor 122 may include one or more processing devices, and the memory device 124 may include one or more tangible, non-transitory, machine-readable media. By way of example, such machine- readable media can include RAM, ROM, EPROM, EEPROM, CD-ROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by the processor 122 or by any general purpose or special purpose computer or other machine with a processor. [0036] To this end, the controller 120 may be communicatively coupled to one or more components of the purge system 80 through a communication system 126. In some embodiments, the communication system 126 may communicate through a wireless network (e.g., wireless local area networks [WLAN], wireless wide area networks [WWAN], near field communication [NFC]). In some embodiments, the communication system 126 may communicate through a wired network (e.g., local area networks [LAN], wide area networks [WAN]). For example, as shown in FIGS. 7-13, the controller 120 may communicate to a number of elements of the purge system 80 such as the pumps 110, the thermoelectric assemblies 82, the stop valves 112, and other components. In some embodiments, functions of the controller 120 and the control panel 40 (FIGS. 3 and 4) as described herein may be controlled through a single controller. In some embodiments, the single controller may be the control panel 40 or the controller 120.

[0037] As discussed in further detail below, as chilled fluid flows through the purge coil 116 of the purge heat exchanger 114, the chilled fluid may exchange heat with a mixture of refrigerant vapor and NCG that has been pulled from the condenser 34 or from another part of the system. As mentioned above, due to the low pressures of the vapor compression system 14 while in operation relative to ambient pressures, the NCG may be drawn into the evaporator 38 and travel through the vapor compression system 14 to accumulate in the condenser 34. Specifically, the NCG may accumulate in one or more portions of the condenser 34. Accordingly, the mixture of the NCG and the refrigerant vapor may be pulled from the one or more portions of the condenser 34. Generally, during normal operation, one or more portions in which the NCG accumulate may be substantially below a discharge baffle, near the middle of the condenser 34, near an outlet of the condenser 34, near a top of the condenser 34, or any combination thereof.

[0038] The NCG that have accumulated in the condenser 34 may be mixed with refrigerant vapor. The NCG and refrigerant vapor mixture may be drawn through a conduit 128 into the purge chamber 118 of the purge heat exchanger 114, which may be due at least in part to a temperature and/or pressure differential created by the chilled fluid passing through the purge coil 116 of the purge heat exchanger 114. In some embodiments, a compressor 129 may be disposed along the conduit 128. The compressor 129 may pump the NCG and refrigerant vapor mixture from the condenser 34 into the purge chamber 118 of the purge heat exchanger 114. Particularly, the compressor 129 is configured to increase a pressure of the mixture before the mixture enters the purge heat exchanger 114. In this manner, the temperature at which the refrigerant vapor of the mixture condenses in the purge heat exchanger 114 is increased, thereby reducing a load on the purge system 80.

[0039] As the NCG and refrigerant vapor mixture comes into contact with the low temperature surface of the purge coil 116, the refrigerant vapor will condense into refrigerant liquid and create a partial vacuum within the purge chamber 118 of the purge heat exchanger 114, thereby drawing in more of the NCG and refrigerant vapor mixture from the condenser 34 through the conduit 128. In some embodiments, as mentioned above, the NCG and refrigerant vapor mixture may be drawn through the conduit 128 and into the purge heat exchanger 114 due to the compressor 129. Further, as the NCG and refrigerant vapor mixture enters the purge heat exchanger 114 and the refrigerant vapor condenses into refrigerant liquid, the refrigerant liquid will gather in the bottom of the purge heat exchanger 114. Indeed, due at least partially to a density difference between the condensed refrigerant liquid and the NCG, the NCG and other uncondensed refrigerant vapor will collect towards the top of the purge heat exchanger 114, while the condensed refrigerant liquid will collect at the bottom of the purge heat exchanger 114. Accordingly, as more of the refrigerant vapor of the NCG and refrigerant vapor mixture condenses within the purge heat exchanger 114, a liquid level of the refrigerant liquid within the purge heat exchanger 114 will rise.

[0040] Once the liquid level of the refrigerant liquid has reached a predetermined threshold in the purge heat exchanger 114, the refrigerant liquid will be drained through a conduit 130 to the condenser 34, the evaporator 38, or both, and the NCG will be pumped out of the purge heat exchanger 114 by a vacuum pump 132 through a conduit 134. The vacuum pump 132 may then expel the NCG into the atmosphere. In some embodiments, the NCG may be at a high pressure within the purge heat exchanger 114 relative to a pressure of the atmosphere due to the compressor 129 increasing a pressure of the NCG and refrigerant vapor mixture prior to the mixture entering the purge heat exchanger 114. Accordingly, due to the pressure differential between the NCG within the purge heat exchanger 114 and the atmosphere, the NCG may expelled into the atmosphere through a stop valve 112 of the conduit 134 without use of the vacuum pump 132.

[0041] In some embodiments, the purge heat exchanger 114 may be disposed vertically above the condenser 34 and the evaporator 38. In this manner, the refrigerant liquid may flow to the condenser 34, the evaporator 38, or both, due at least in part to the head pressure differential created by the height differential of the purge heat exchanger 114 relative to the condenser 34 and the evaporator 38. In some embodiments, the condenser 34 may be disposed vertically above the evaporator 38, thereby allowing the refrigerant liquid to flow more easily to the evaporator 38 relative to the condenser 34 from the purge heat exchanger 114.

[0042] In some embodiments, the purge heat exchanger 114 may include one or more sensors 138, which may include one or more temperature sensors, pressure sensors, liquid level sensors, ultrasonic sensors, or any combination thereof. For example, one sensor 138 of the one or more sensors 138 may measure the liquid level of the refrigerant liquid within the purge heat exchanger 114 and send data regarding the liquid level to the controller 120. If the liquid level is approaching, matching, and/or exceeding the predetermined liquid level threshold, the controller 120 may send a signal to one or more of the stop valves 112 to allow the refrigerant liquid to drain to the condenser 34, the evaporator 38, or both, as described above. Similarly, the controller 120 may send a signal to the pump 132 and/or one or more of the stop valves 112 to release the NCG through the pump 132 into the atmosphere.

[0043] In some embodiments, the controller 120 may determine whether there is a significant or predetermined amount of NCG within the condenser 34 before allowing the NCG and refrigerant vapor mixture to enter the purge heat exchanger 114, such as by activating one or more of the stop valves 112. To determine whether there is a significant or predetermined amount of NCG within the condenser 34, another sensor 138 of the one or more sensors 138 may measure one or more parameters related to a performance of the vapor compression system 14 and send data indicative of the one or more parameters to the controller 120 to analyze and process. Specifically, the controller 120 may determine a performance level of the vapor compression system 14 based on the one or more parameters. If the controller 120 determines that the performance level of the vapor compression system 14 is below a predetermined threshold, the controller 120 may allow the condenser 34 to be purged as described above by opening an appropriate stop valve 112 and allowing the mixture of NCG and refrigerant vapor to flow to the purge heat exchanger 114 from the condenser 34. In some embodiments, the controller 120 may purge the condenser 34 as described above based on a predetermined schedule.

[0044] Additionally, or in the alternative, one of the sensors 138 may measure a saturation temperature and an actual temperature within the condenser 34 and send data indicative of the saturation and actual temperatures to the controller 120 to analyze and process. The controller 120 may then determine whether the saturation temperature substantially matches the actual temperature. If the saturation temperature does not substantially match the actual temperature, the controller 120 may allow the condenser 34 to be purged as described above by opening an appropriate stop valve 112 and allowing the mixture of NCG and refrigerant vapor to flow to the purge heat exchanger 114 from the condenser 34.

[0045] As discussed herein, the purge heat exchanger 114 may receive a chilled fluid that flows through the purge coil 116 to condense the refrigerant vapor pulled from the condenser 34. In some embodiments, the purge coil 116 may include internal and/or external fins configured to increase a rate of heat transfer between the purge coil 116, the fluid within the purge coil 116, and/or the fluid that is external to the purge coil 116 and internal to the purge heat exchanger 114. FIGS. 7-13 depict embodiments of the purge system 80 used to chill the fluid flowing through the purge coil 116. For example, as shown in FIG. 7, the purge system 80 may include a closed fluid loop 160 configured to chill a fluid and flow the chilled fluid through the purge coil 116 to condense the refrigerant vapor within the purge heat exchanger 114. Particularly, the fluid within closed fluid loop 160 may be a brine and/or a water/glycol mixture with a low freezing point. [0046] The closed fluid loop 160 may utilize a liquid pump 162 to pump the fluid through a conduit 164 and the purge coil 116 of the closed fluid loop 160. Indeed, the liquid pump 162 may be a modified pump that is configured to pump brine and/or a water/glycol mixture. Further, as shown in the figure, multiple thermoelectric assemblies 82 may be coupled to the conduit 164 and configured to remove heat from the fluid as it flows through the conduit 164, as described above in reference to FIGS. 5 and 6. There may be any suitable number of thermal electric assemblies 82 coupled to the conduit 164.

[0047] In certain embodiments, as shown in FIG. 8, the purge system 80 may utilize fluid from another source such as the cooling fluid of the cooling load 62 (FIGS. 3 and 4). In other words, the purge system 80 may utilize fluid from a cooling system of a building, such as the building 12 (FIG. 1) through an open fluid loop 165. In certain embodiments, the fluid may be water, brine, or a water/glycol mixture. Particularly, a liquid pump 162 of the open fluid loop 165 may draw fluid from the supply line 60S through a conduit 166 and supply the fluid to the purge coil 116 of the purge heat exchanger 114. As the fluid flows through the conduit 166 to the purge coil 116, the fluid may be chilled via thermoelectric assemblies 82 that are coupled to the conduit 166 and configured to remove heat from the fluid, as discussed above. In this manner, the purge coil 116 may receive fluid that has been chilled via the thermoelectric assemblies 82. As the chilled fluid flows through the purge coil 116, the refrigerant vapor from the condenser 34 may condense within the purge chamber 118. After flowing through the purge coil 116, the fluid may be returned to the supply line 60S. Indeed, the amount of fluid drawn from the supply line 60S may be negligible relative to the overall mass flowrate of the fluid through the supply line 60S. Further, the fluid that is drawn from the supply line 60S and routed to the purge coil 116 may be at a temperature that is lower than the ambient temperature due at least in part to the heat exchange process within the evaporator 38 described above. Therefore, the thermoelectric assemblies 82 may remove a reduced amount of heat from the fluid of the open fluid loop 165 for the fluid to be at an adequately low temperature to condense the refrigerant vapor within the purge heat exchanger 114. [0048] In certain embodiments, as shown in FIG. 9, the purge system 80 may utilize chilled fluid from the closed fluid loop 160 and chilled fluid from the open fluid loop 165, which may function similar to embodiments discussed in reference to FIGS. 7 and 8, respectively. Particularly, the closed fluid loop 160 may utilize the liquid pump 162 to flow the fluid through the conduit 168 and through the purge coil 116. As the fluid flows through the conduit 168, the thermoelectric assemblies 82 that are coupled to the conduit 168 may remove heat from the fluid, thereby chilling the fluid. Indeed, the fluid may be a brine, water, and/or a water/glycol mixture. Accordingly, the liquid pump 162 of the closed fluid loop 160 may be a modified pump that is configured to pump water, brine, and/or a water/glycol mixture.

[0049] The purge system 80, as shown in the embodiment of FIG. 9, may also include the open fluid loop 165, which may utilize fluid from the cooling system of a building, such as the building 12 (FIG. 1). Particularly, the liquid pump 162 of the open fluid loop 165 may draw fluid from the supply line 60S and pump the fluid through a conduit 170 to the purge coil 116 of the purge heat exchanger 114. As the fluid flows through the conduit 170 to the purge coil 116, thermoelectric assemblies 82 that are coupled to the conduit 170 may remove heat from the fluid, thereby further chilling the fluid. In certain embodiments, the fluid drawn from the supply line 60S may be water, brine, or a water/glycol mixture. Accordingly, in such embodiments, the liquid pump 162 of the open fluid loop 165 may be configured to pump water, brine, or a water/glycol mixture, respectively.

[0050] As discussed above, the closed fluid loop 160 and the open fluid loop 165 may flow chilled fluid through the purge coil 116 of the purge heat exchanger 114. Specifically, in certain embodiments, the purge heat exchanger 114 may include two separate purge coils 116, which may separately receive chilled fluid from separate fluid loops, such as from the closed fluid loop 160 and from the open fluid loop 165, as discussed in further detail below in FIG. 14. Further, as discussed in further detail below, the purge heat exchanger 114 may include a single purge coil 116 that is configured to receive chilled fluid from separate fluid loops, such as from both the closed fluid loop 160 and the open fluid loop 165, at separate times based on operation of one or more stop valves 112, as discussed in further detail below in FIG. 15. Additionally, or in the alternative, the purge coil 116 may receive a mixture of fluid from separate fluid loops based on operation of one or more stop valves 112, also as discussed in further detail below in FIG. 15. Particularly, the controller 120 may send one or more signals to the appropriate stop valves 112 to control the flow of chilled fluids through the purge heat exchanger 114 as discussed above.

[0051] In certain embodiments, as shown in FIG. 10, the purge system 80 may include a refrigerant loop 172 that is configured to flow chilled refrigerant through the purge coil 116 to condense the vapor refrigerant pulled from the condenser 34. Particularly, a liquid pump 162 of the refrigerant loop 172 that is configured to pump liquid refrigerant may pull liquid refrigerant from the evaporator 48 through a conduit 174. In some embodiments, the liquid refrigerant pulled from the evaporator 38 may include a portion of vapor refrigerant. In other words, the liquid pump 162 may pull a two-phase mixture of vapor refrigerant and liquid refrigerant from the evaporator 38. Accordingly, in some embodiments, the purge system 80 may include a flash tank, such as the intermediate vessel 70 (FIG. 4), which is disposed along the conduit 174 between the liquid pump 162 and the evaporator 38. To this end, the liquid refrigerant may be separated from the vapor refrigerant within the flash tank. The liquid refrigerant may be drawn from the flash tank by the liquid pump 162 along the conduit 174, and the vapor refrigerant may be routed from the flash tank to an outlet side of the evaporator 38. The liquid pump 162 of the refrigerant loop 172 may then pump the liquid refrigerant through the purge coil 116 and back to the evaporator 38. Before reaching the purge coil 116, the liquid refrigerant may traverse one or more portions of the conduit 174 to which thermoelectric assemblies 82 are coupled. Specifically, the thermoelectric assemblies 82 may remove heat from the liquid refrigerant as it flows through the conduit 174, thereby chilling the liquid refrigerant to a subcooled state. In this manner, the refrigerant may remain in a liquid state as it flows through the purge coil 116, transfers heat to the mixture of refrigerant vapor and NCG, and flows back to the evaporator 38. Indeed, the liquid pump 162 of the refrigerant loop 172 may be a modified pump that is configured to pump refrigerant liquid. [0052] Further, in certain embodiments, as shown in FIG. 11, the purge system 80 may include the refrigerant loop 172 and the open fluid loop 165 which may both flow chilled fluid into the purge heat exchanger 114 to separate the mixture of refrigerant vapor and NCG that is pulled from the condenser 34 by condensing refrigerant vapor of the mixture. Indeed, the refrigerant loop 172 may function as described above in reference to FIG. 10, and the open fluid loop 165 may function as described above in reference to FIG. 9. Further, also as discussed above, the refrigerant loop 172 and the open fluid loop 165 may flow chilled fluid through separate respective purge coils 116 in certain embodiments, or may flow chilled fluid through a single purge coil 116. Particularly, the purge coil 116 may receive a mixture of fluid from separate fluid loops based on operation of one or more stop valves 112 (shown in FIGS. 14 and 15). Specifically, the controller 120 may send one or more signals to the appropriate stop valves 112 to control the flow of chilled fluids through the purge heat exchanger 114.

[0053] Further, in all of the embodiments discussed herein, the purge system 80 may utilize adsorption chambers 180 to remove NCG from the vapor compression system 14. For example, as discussed above, the vacuum pump 132 may remove gases from the purge chamber 118 of the purge heat exchanger 114. Particularly, in certain embodiments, the vacuum pump 132 may remove NCG and refrigerant vapor from the purge chamber 118. Accordingly, the adsorption chambers 180 may remove a portion of refrigerant vapor drawn in by the vacuum pump 132 before expelling the NCG into the atmosphere. To illustrate, the vacuum pump 132 may pump the mixture of NCG and refrigerant vapor, or“mixture,” through a conduit 182 to one or more of the adsorption chambers 180. As the mixture traverses through one of the adsorption chambers 180, the mixture may be passed through a modified material 184 of the adsorption chamber 180, and the refrigerant vapor may be adsorbed, or attracted, into and/or onto the modified material 184 due to the properties of the modified material 184 and the refrigerant vapor. For example, electrochemical properties may aid in adsorption as described herein. Further, as the mixture traverses through the adsorption chamber 180, the NCG may not be adsorbed into the modified material 184 also due at least in part to the properties of the NCG and/or the modified material 184. Accordingly, the NCG may pass through the modified material 184 and continue through an air outlet valve 186 to be expelled into the atmosphere.

[0054] As the modified material 184 adsorbs the refrigerant, the modified material 184 may eventually become saturated with the refrigerant and may no longer efficiently adsorb additional refrigerant. Accordingly, heaters 188, such as immersion heaters, outer cable heaters, or band heaters, may be activated to provide thermal energy to the modified material 184 to heat the refrigerant. In this manner, the heaters 188 will help the refrigerant overcome the bonds of the modified material 184, such that the modified material 184 releases the refrigerant in a vapor state. Once released from the modified material 184, the refrigerant vapor may have a high pressure relative to pressures within the evaporator 38 such that the refrigerant vapor flows to the evaporator 38 through a conduit 190.

[0055] In some embodiments, the stop valves 112 may allow the mixture to flow to only certain adsorption chambers 180 at a time. In this manner, the adsorption chambers 180 may continuously receive and filter the mixture as described above. For example, the controller 120 may control the stop valves 112 to allow the mixture to be filtered by one or more specific adsorption chambers 180 of the adsorption chambers 180. Once the specific adsorption chamber 180 becomes saturated with the refrigerant, the controller 120 may stop flow of the mixture to the specific adsorption chamber 180 and allow the mixture to flow to a different adsorption chamber 180. Once the controller 120 has stopped flow to the specific adsorption chamber 180, the controller may activate the heater 188 associated with the specific adsorption chamber 180 to allow the refrigerant vapor to flow to the evaporator 38 as described above. Indeed, while the specific adsorption chamber 180 is being heated, the different adsorption chamber 180 may continue to filter the mixture. Once the specific adsorption chamber 180 is sufficiently unsaturated with the refrigerant, the controller 120 may once again activate one or more of the stop valves 112 to allow the mixture to flow the specific adsorption chamber 180. To this end, the purge system 80 may include 1, 2, 3, 4, 5, 6, or any other suitable number of individual adsorption chambers 180 to allow continuous filtration of the mixture. [0056] Further, in certain embodiments, as shown in FIG. 12, the purge system 80 may include the closed fluid loop 160 and an open intermediate fluid loop 200, such as an open fluid loop. Particularly, the closed fluid loop 160 may utilize the liquid pump 162 to flow a fluid, which may be water, brine, or a water/glycol mixture, through a conduit 201 and the purge coil 116. Indeed, the liquid pump 162 may be a modified pump that is configured to pump water, brine, or a water/glycol mixture. As the liquid pump 162 pumps the fluid of the closed fluid loop 160 through the conduit 201, a first set of thermoelectric assemblies 82a may chill the fluid as discussed above. In this manner, as the chilled fluid of the closed fluid loop 160 flows through the purge coil 116, the chilled fluid may separate the mixture of NCG and refrigerant vapor by condensing the refrigerant vapor within the purge chamber 118 as discussed above.

[0057] Further, it should be noted that the cold side 86 of the first set of thermoelectric assemblies 82a may be coupled to the conduit 201 while the hot side 84 of the first set of thermoelectric assemblies 82a may be coupled to a conduit 202 configured to flow another chilled fluid. Specifically, the conduit 202, which is coupled to the hot side 84 of the first set of thermoelectric assemblies 82a, may be part of the open intermediate fluid loop 200.

[0058] To illustrate, the liquid pump 162 of the open intermediate fluid loop 200 may draw a fluid, which may be water, brine, a water/glycol mixture, or a combination thereof, from the supply line 60S of the cooling load 62 (FIG. 3 and 4) through a conduit 204. Particularly, in certain embodiments, the liquid pump 162 of the open intermediate fluid loop 200 may utilize fluid from a cooling system of a building, such as the building 12 (FIG. 1). Indeed, the fluid pumped from the supply line 60S may be water, brine, or a water/glycol mixture and the liquid pump 162 of the open intermediate fluid loop 200 may be configured to pump water, brine, or a water/glycol mixture, respectively. The liquid pump 162 of the open intermediate fluid loop 200 may then pump the fluid through a conduit 206, to which a second set of thermoelectric assemblies 82b may be coupled. As the fluid of the open intermediate fluid loop 200 passes through the conduit 206, the second set of thermoelectric assemblies 82b may remove heat from the fluid. After passing through the conduit 206, the fluid of the open intermediate fluid loop 200 may pass through the conduit 202. Particularly, as mentioned above, the conduit 202 may be coupled to the hot sides 84 of the first set of thermoelectric assemblies 82a. In this manner, as the fluid passes through the conduit 202 of the second set of thermoelectric assemblies 82b, the fluid may absorb some heat from the hot sides 84 of the thermoelectric assemblies 82b.

[0059] Indeed, the first set of thermoelectric assemblies 82a may utilize the chilled fluid flowing through the conduit 202 in place of a fan 100 (FIGS. 4 and 5) to increase the capability of the second thermoelectric assemblies 82a to chill the fluid in the closed fluid loop 160 to a lower temperature. For example, the chilled fluid flowing through the conduit 202 may be at a lower temperature than ambient air, which the fan 100 may otherwise utilize to cool the hot side 84. Therefore, by utilizing the chilled fluid within the conduit 202, the temperature difference between the cold side 86 and the hot side 84 may be reduced, thereby increasing the heat transfer effectiveness of the purge system 80.

[0060] After the fluid of the open intermediate fluid loop 200 flows through the conduit 202 to cool the hot side 84 of the first set of thermoelectric assemblies 82a, the fluid may flow to the return line 60R via a conduit 208 to once again be chilled within the evaporator 38 as discussed above.

[0061] In certain embodiments, as shown in FIG. 13, the purge system 80 may utilize the refrigerant loop 172 to condense the refrigerant vapor within the purge heat exchanger and utilize the intermediate cooling fluid loop 200 to cool the thermoelectric assemblies 82a that are used to cool the fluid in the refrigerant loop 172 that is chilling the purge coil 116. For example, as discussed previously in FIG. 10, the purge system 80 may utilize the refrigerant loop 172 to flow refrigerant from the evaporator 38 to the purge coil 116 of the purge heat exchanger 114 in order to separate the mixture of NCG and refrigerant vapor that is pulled from the condenser 34.

[0062] For example, the liquid pump 162 of the refrigerant loop 172 may pump refrigerant from the evaporator 38 through a conduit 210 and through the purge coil 116 of the purge heat exchanger 114. Further, as shown, a first set of thermoelectric assemblies 82a may be coupled to the conduit 210. Therefore, as the refrigerant flows through the conduit 210 to the purge coil 116, the first set of thermoelectric assemblies 82a may chill, or subcool, the refrigerant. Particularly, the thermoelectric assemblies 82a may chill the refrigerant such that the refrigerant remains in a liquid state throughout the refrigerant loop 172.

[0063] Further, it should be noted that the cold side 86 of the first set of thermoelectric assemblies 82a may be coupled to the conduit 210 while the hot side 84 of the first set of thermoelectric assemblies 82a may be coupled to a conduit 212 configured to flow another chilled fluid. Specifically, the conduit 212, which is coupled to the hot side 84 of the first set of thermoelectric assemblies 82a, may be part of the open intermediate fluid loop 200.

[0064] To illustrate, the liquid pump 162 of the open intermediate fluid loop 200 may draw a fluid, which may be water, brine, a water/glycol mixture, or a combination thereof, from the supply line 60S of the cooling load 62 (FIG. 3 and 4) through a conduit 214. Particularly, in certain embodiments, the liquid pump 162 of the open intermediate fluid loop 200 may utilize fluid from a cooling system of a building, such as the building 12 (FIG. 1). Indeed, the fluid pumped from the supply line 60S may be water, brine, or a water/glycol mixture and the liquid pump 162 of the open intermediate fluid loop 200 may be configured to pump water, brine, or a water/glycol mixture, respectively. The liquid pump 162 of the open intermediate fluid loop 200 may then pump the fluid through a conduit 216, to which a second set of thermoelectric assemblies 82b may be coupled. As the fluid of the open intermediate fluid loop 200 passes through the conduit 216, the second set of thermoelectric assemblies 82b may remove heat from the fluid. After passing through the conduit 216, the fluid of the open intermediate fluid loop 200 may pass through the conduit 212. Particularly, as mentioned above, the conduit 212 may be coupled to the hot sides 84 of the first set of thermoelectric assemblies 82a. In this manner, as the fluid of the intermediate fluid loop 200 passes through the conduit 212 of the first set of thermoelectric assemblies 82a, the fluid may absorb some heat from the hot sides 84 of the first set of thermoelectric assemblies 82a. [0065] Indeed, the first set of thermoelectric assemblies 82a may utilize the chilled fluid flowing through the conduit 212 in place of the fan 100 (FIGS. 4 and 5) to increase the heat removal capabilities of the second thermoelectric assemblies 82a. For example, the chilled fluid flowing through the conduit 212 may be at a lower temperature than ambient air, which the fan 100 may otherwise utilize to cool the hot side 84. Therefore, by utilizing the chilled fluid within the conduit 212, the temperature difference between the cold side 86 and the hot side 84 may be reduced, thereby increasing the heat transfer effectiveness of the purge system 80.

[0066] After the fluid of the open intermediate fluid loop 200 flows through the conduit 212 to cool the hot side 84 of the first set of thermoelectric assemblies 82a, the fluid may flow to the return line 60R via a conduit 220 to once again be chilled within the evaporator 38 as discussed above.

[0067] As discussed above, the purge heat exchanger 114 may receive chilled fluid from more than one fluid loop, such as the closed fluid loop 160, the open fluid loop 165, and/or the refrigerant loop 172. Particularly, the heat exchanger 114 may receive chilled fluid from two separate fluid loops. Accordingly, in certain embodiments, as shown in FIG. 14, the purge heat exchanger 114 may include a first purge coil 1 l6a, which may be part of a first fluid loop 222a, and may also include a second purge coil 1 l6b, which may be part of a second fluid loop 222b. Indeed, in certain embodiments, the first and second fluid loops 222a, 222b may be part of the closed fluid loop 160, the open fluid loop 165, or the refrigerant loop 172. Particularly, in the illustrated embodiment, the first purge coil 116a and the first fluid loop 222b may be separate from the second purge coil 116b and the second fluid loop 222. In such embodiments, the controller 120 may operate one or more of the stop valves 112 to flow chilled fluid through the first fluid loop 222a, the second fluid loop 222a, or both, through the purge heat exchanger 114.

[0068] Further, in certain embodiments, as shown in FIG. 15, the purge heat exchanger 114 may include a single purge coil H6c, which may receive chilled fluid from the first fluid loop 222a, the second fluid loop 222b, or both. Indeed, the single purge coil 116c may be part of the first fluid loop 222a, the second fluid loop 222b, or both. That is, the controller 120 may operate the appropriate stop valves 112 to flow chilled fluid from the first fluid loop 222a, the second fluid loop 222b, or both as a mixture, through the single purge coil 116c of the purge heat exchanger 114.

[0069] Indeed, as discussed above in reference to FIGS. 14 and 15, the purge heat exchanger 114 may receive chilled fluid from two separate fluid loops, such as the first fluid loop 222a and the second fluid loop 222b. In certain embodiments, the first and second fluid loops 222a, 222b may flow different types of fluid. For example, the first fluid loop 222a may utilize water as a chilled fluid while the second fluid loop 222b may utilize brine, refrigerant, or a water/glycol mixture. In such embodiments, the water within the first fluid loop 222a may have a first freezing temperature and the brine, refrigerant, or water/glycol mixture within the second fluid loop 222b may have a second freezing temperature that is lower than the first freezing temperature. Accordingly, the fluid within the second fluid loop 222b may be chilled to a lower temperature than the fluid with the first fluid loop 222a before the fluids start to solidify, or freeze. Therefore, in certain embodiments, the controller 120 may operate the stop valves 112 accordingly to only utilize the chilled fluid in either the first fluid loop 222a, the second fluid loop 222b, or both, depending on the type of chilled fluid and the amount of cooling that may be used to sufficiently condense the refrigerant vapor within the purge heat exchanger 114.

[0070] Further, it should be noted that embodiments discussed herein with respect to FIG. 7-13, specifically the thermoelectric assemblies 82 may be utilized if the vapor compression system 14 is in operation or if the vapor compression system 14 is not in operation. Yet further, as shown in FIGS. 7-13, in some embodiments, the liquid pumps 162 and/or the vacuum pump 132 may be powered by one or more motors 240, which may be any suitable motor. In some embodiments, the controller 120 may control the liquid pump 162 and/or the vacuum pump 132 through communication with the one or more motors 240. Particularly, the controller 120 may operate the pumps 162, 132 based on temperature and/or pressure data obtained from the one or more sensors 138 of the purge system 30. In some embodiments, the one or more motors 240 may receive power from the power source 90. Moreover, in some embodiments, the controller 120 may control the amount of power sent from the power source 90 to the thermoelectric assemblies 82 to set an appropriate heat removal amount. For example, in some embodiments, the controller 120 may decrease the amount of power sent to the thermoelectric assemblies 82 to save in power costs or to decrease an amount of heat removal performed by the thermoelectric assemblies 82.

[0071] Accordingly, the present disclosure is directed to providing systems and methods for purging a low-pressure HVAC system (e.g., chiller system, vapor compression system) of NCG that may have entered during operation. Specifically, a purge system may purge the HVAC system of NCG by utilizing a chilled fluid that has been chilled via thermoelectric assemblies. The disclosed embodiments enable the HVAC system to be purged of the NCG without using additional refrigerant, which may have a high GWP. Moreover, it should also be understood that features of any of the embodiments discussed herein may be combined with any other embodiments or features discussed herein.

[0072] While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the claimed invention). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.