US20150354862A1

US20150354862A1 - Heat Pump Desuperheater and Charge Robber

Info

Publication number: US20150354862A1
Application number: US14/720,363
Authority: US
Inventors: Stephen Stewart Hancock
Original assignee: Trane International Inc
Current assignee: Trane International Inc
Priority date: 2014-06-10
Filing date: 2015-05-22
Publication date: 2015-12-10
Also published as: CN105157283A; CN105157283B

Abstract

Systems and methods are disclosed which may include providing a desuperheater/charge robber (DSHCR) system in a heating, ventilation, and/or air-conditioning (HVAC) system, wherein the DSHCR system is configured to selectively allow a flow of refrigerant through a desuperheater heat exchanger when the HVAC system is operated in a cooling mode and selectively prevent the flow of refrigerant through the desuperheater heat exchanger from a refrigerant fluid circuit when the HVAC system is operated in a heating mode. The desuperheater heat exchanger may also be configured to function as a charge robber and store at least a portion of the refrigerant when the HVAC system is operated in the heating mode.

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. 62/010,341 filed on Jun. 10, 2014 by Stephen Stewart Hancock and entitled “Heat Pump Desuperheater and Charge Robber,” 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

Heating, ventilation, and/or air conditioning (HVAC) systems may generally be used in residential and/or commercial structures to provide heating and/or cooling to climate-controlled areas within these structures. Some HVAC systems may be heat pump systems that include both an indoor unit and an outdoor unit. In a heat pump system, refrigerant charge management remains a critical part of the heat pump design because a majority of the heat pump system's refrigerant charge may reside in the condenser, the condenser being the outdoor coil when operated in a cooling mode and the indoor coil when operated in a heating mode. In high efficiency heat pump systems, the outdoor coil is often much larger than the indoor coil and capable of holding a larger volume of refrigerant. In such systems, a heat pump system charged with an adequate subcooling in the cooling mode may often experience an excessive amount of subcooling in the heating mode, since much of the indoor coil may fill with liquid refrigerant. Traditional heat pump systems often utilize a cylinder, sometimes referred to as a “charge robber,” that may fill with liquid refrigerant during operation of the heat pump system in the heating mode to sequester excess liquid refrigerant which would otherwise flow to the indoor coil.

SUMMARY

In some embodiments of the disclosure, a heating, ventilation, and/or air-conditioning (HVAC) system is disclosed as comprising a desuperheater/charge robber (DSHCR) system configured to (1) selectively allow a flow of refrigerant through a desuperheater heat exchanger when the HVAC system is operated in a cooling mode and (2) selectively prevent the flow of refrigerant through the desuperheater heat exchanger from a refrigerant fluid circuit while keeping the desuperheater heat exchanger in fluid communication with a high pressure side of the refrigerant fluid circuit when the HVAC system is operated in a heating mode.
In other embodiments of the disclosure, a method of operating an HVAC system is disclosed as comprising: flowing refrigerant through a desuperheater heat exchanger when the HVAC system is operated in a cooling mode; switching the HVAC system from the cooling mode to a heating mode; and preventing refrigerant from flowing through the desuperheater heat exchanger while keeping the desuperheater heat exchanger in fluid communication with a high pressure side of the refrigerant fluid circuit when the HVAC system is operated in the heating mode.

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 HVAC system comprising a desuperheater/charge robber system and configured in a cooling mode according to an embodiment of the disclosure;

FIG. 2 is a schematic diagram of the HVAC system of FIG. 1 comprising the desuperheater/charge robber system of FIG. 1 and configured in a heating mode according to an embodiment of the disclosure;

FIG. 3 is a schematic diagram of an HVAC system comprising a desuperheater/charge robber system and configured in a cooling mode according to another embodiment of the disclosure;

FIG. 4 is a schematic diagram of the HVAC system of FIG. 3 comprising the desuperheater/charge robber system of FIG. 3 and configured in a heating mode according to another embodiment of the disclosure;

FIG. 5 is a flowchart of a method of operating an HVAC system according to an embodiment of the disclosure; and

FIG. 6 is a flowchart of a method of operating an HVAC system according to another embodiment of the disclosure.

DETAILED DESCRIPTION

In some cases, it may be desirable to provide a desuperheater/charge robber (DSHCR) system in a heating, ventilation, and/or air conditioning (HVAC) system. For example, in high efficiency heat pump systems comprising both an indoor and an outdoor unit, where the outdoor coil of the outdoor unit is often much larger than the indoor coil of the indoor unit and capable of holding a larger volume of refrigerant, it may be desirable to provide a DSHCR system to improve cooling performance when the heat pump system is operated in a cooling mode and to sequester excess liquid refrigerant during operation of the heat pump system in a heating mode. In some embodiments, systems and methods are disclosed that comprise providing a DSHCR system in an outdoor unit of a heat pump system that functions as a desuperheater in a cooling mode and a charge robber in a heating mode.
Referring now to FIG. 1, a schematic diagram of an HVAC system 100 comprising a DSHCR system 106 is shown configured in a cooling mode according to an embodiment of the disclosure. Most generally, HVAC system 100 comprises a heat pump system that may be selectively operated to implement one or more substantially closed thermodynamic refrigeration cycles to provide a cooling functionality (hereinafter, “cooling mode”) and/or a heating functionality (hereinafter, “heating mode”). Most generally, HVAC system 100, configured as a heat pump system, generally comprises both an indoor unit 102 and an outdoor unit 104. It will be appreciated that, although not pictured, the HVAC system 100 may also comprise a system controller that is configured to generally communicate with an indoor controller of the indoor unit 102 and/or an outdoor controller of the outdoor unit 104 and/or control operation of the indoor unit 102 and/or the outdoor unit 104. Additionally, the system controller may comprise a temperature sensor and may further be configured to control heating and/or cooling of zones associated with the HVAC system 100.
Indoor unit 102 generally comprises an indoor heat exchanger 108, an indoor fan 110, and an indoor metering device 112. 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 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 electronically-controlled motor driven electronic expansion valve (EEV). In some embodiments, however, the indoor metering device 112 may comprise a thermostatic expansion valve, a capillary tube assembly, and/or any other suitable metering device. 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 metering device 120. Additionally, as will be discussed later herein, the outdoor unit 104 also comprises the DSHCR system 106. Further, it will be appreciated that while the reversing valve 122 may generally be associated with the outdoor unit 104, the reversing valve 122 may be described as being a component of the DSHCR system 106, since operation of the DSHCR system 106 relies heavily on the operation of the reversing valve 122. 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 multiple 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, 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. In some embodiments, and as will be discussed later herein, the outdoor fan 118 may also be configured to provide airflow through a desuperheater heat exchanger 124. 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 be configured 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 outdoor metering device 120 may generally comprise a thermostatic expansion valve. In some embodiments, however, the outdoor metering device 120 may comprise an electronically-controlled motor driven EEV similar to indoor metering device 112, a capillary tube assembly, and/or any other suitable metering device. In some embodiments, while the outdoor metering device 120 may be configured to meter the volume and/or flow rate of refrigerant through the outdoor metering device 120, the outdoor metering device 120 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 outdoor metering device 120 is such that the outdoor metering device 120 is not intended to meter or otherwise substantially restrict flow of the refrigerant through the outdoor metering device 120.
DSHCR system 106 generally comprises a reversing valve 122, a desuperheater heat exchanger 124, and a three-way valve 126. As previously stated, it will be appreciated that while the reversing valve 122 may generally be associated with the outdoor unit 104, the reversing valve 122 may be described herein as being a component of the DSHCR system 106, since operation of the DSHCR system 106 relies heavily on the operation of the reversing valve 122. The reversing valve 122 may generally comprise a four-way reversing valve. The reversing valve 122 comprises a main inlet port 136, a first variable port 130, a main outlet port 132, and a second variable port 134. As will be discussed later herein, the reversing valve 122 may generally be selectively controlled to alter a flowpath of refrigerant in the HVAC system 100 by selectively altering a refrigerant flowpath through the main inlet port 136, the first variable port 130, the main outlet port 132, and the second variable port 134. In some embodiments, the reversing valve 122 may be selectively controlled by an outdoor controller of the outdoor unit 104 and/or a system controller of the HVAC system 100. The reversing valve 122 may also comprise an electrical solenoid, relay, and/or other device configured to selectively move a component of the reversing valve 122 between operational positions to alter the flowpaths through the reversing valve 122 and consequently the HVAC system 100.
The desuperheater heat exchanger 124, also commonly referred to as simply a desuperheater, may generally be described as comprising a desuperheater heat exchanger inlet 127 and a desuperheater heat exchanger outlet 129. The desuperheater heat exchanger inlet 127 may generally be connected in fluid communication with a first outlet port 125 of a three-way valve 126, while the desuperheater heat exchanger outlet 129 may generally be connected in fluid communication between a second outlet port 128 of the three-way valve 126 and the main inlet port 136 of the reversing valve 122. When the HVAC system 100 is operated in the cooling mode, the desuperheater heat exchanger 124 may generally be configured to promote heat transfer between a refrigerant carried within internal passages of the desuperheater heat exchanger 124 and an airflow that contacts the desuperheater heat exchanger 124 but that is segregated from the refrigerant. However, when the HVAC system 100 is operated in the heating mode, the desuperheater heat exchanger 124 may, in conjunction with other components of the DSHCR system 106, be removed from the refrigerant fluid circuit and perform the function of a traditional charge robber to store excess liquid refrigerant. In some embodiments, desuperheater heat exchanger 124 may comprise a plate-fin heat exchanger. However, in other embodiments, desuperheater heat exchanger 124 may comprise a spine fin heat exchanger, a microchannel heat exchanger, or any other suitable type of heat exchanger.
The three-way valve 126 may generally comprise a solenoid-actuated valve, a relay-controlled valve, and/or any other valve that is configured to selectively alter a flow of fluid through at least a first and a second flowpath. The three-way valve 126 may generally comprise an inlet port 123, a first outlet port 125, and a second outlet port 128. The inlet port 123 of the three-way valve 126 may be connected in fluid communication with a discharge side of the compressor 116. The first outlet port 125 of the three-way valve 126 may generally be selectively connected in fluid communication with the desuperheater heat exchanger inlet 127, while the second outlet port 128 may generally be selectively connected in fluid communication with the main inlet port 136 of the reversing valve 122. The three-way valve 126 may generally be configured to receive a flow of refrigerant from the compressor 116 that enters the three-way valve 126 through the inlet port 123. Additionally, the three-way valve 126 may be selectively controlled to divert refrigerant entering the inlet port 123 to the first outlet port 125 or the second outlet port 128, depending on the configuration of the three-way valve 126 and/or the HVAC system 100. In some embodiments, the three-way valve 126 may be selectively controlled by an outdoor controller of the outdoor unit 104 and/or a system controller of the HVAC system 100.
Still referring to FIG. 1, the HVAC system 100 is shown configured for operating in a cooling mode. When the HVAC system 100 is operated in the cooling mode, heat may generally be absorbed by refrigerant at the indoor heat exchanger 108 and rejected from the refrigerant at the outdoor heat exchanger 114 and/or the desuperheater heat exchanger 124. Starting at the compressor 116, the compressor 116 may be operated to compress refrigerant and pump the relatively high temperature and high pressure refrigerant to the inlet port 123 of the three-way valve 126, where the three-way valve 126 may be selectively configured to divert the refrigerant to the first outlet port 125. Because the first outlet port 125 is connected in fluid communication with the desuperheater heat exchanger inlet 127, refrigerant exiting the three-way valve 126 through the first outlet port 125 may enter the desuperheater heat exchanger 124 through the desuperheater heat exchanger inlet 127.
Within the desuperheater heat exchanger 124, the relatively high temperature refrigerant may transfer heat to an airflow passed through and/or into contact with the desuperheater heat exchanger 124 by the outdoor fan 118. After passing through the desuperheater heat exchanger 124, refrigerant may exit the desuperheater heat exchanger 124 through the desuperheater heat exchanger outlet 129 and flow to a junction of the second outlet port 128 of the three-way valve 126 and the main inlet port 136 of the reversing valve 122. Because the HVAC system 100 is configured for operation in the cooling mode, refrigerant may be prevented by the three-way valve 126 from entering the second outlet port 128. Accordingly, refrigerant may enter the reversing valve 122 through the main inlet port 136, where the reversing valve 122 may be selectively configured to divert the refrigerant to the second variable port 134.
Refrigerant may exit the reversing valve 122 through the second variable port 134 and flow to the outdoor heat exchanger 114, where the refrigerant may transfer additional heat to the airflow that is passed through and/or into contact with the outdoor heat exchanger 114 by the outdoor fan 118, thereby condensing to a subcooled liquid-phase refrigerant before exiting the outdoor heat exchanger 114 and flowing to the outdoor metering device 120. By passing the heated refrigerant through the desuperheater heat exchanger 124 prior to passing the refrigerant through the outdoor heat exchanger 114 and by contacting the outdoor heat exchanger 114 with an ambient airflow generated by the outdoor fan 118 prior to the heated airflow encountering the relatively higher temperature desuperheater heat exchanger 124, the temperature differentials between the airflow generated by the outdoor fan 118 and the respective heat exchangers 124, 114 may be maximized. Accordingly, the desuperheater heat exchanger 124 and/or the DSHCR system 106 may increase cooling performance and/or the efficiency of the HVAC system 100 as compared to a traditional system that may not comprise a desuperheater heat exchanger 124 and/or a DSHCR system 106.
After exiting the outdoor heat exchanger 114, the refrigerant may flow through and/or bypass the outdoor metering device 120, such that refrigerant flow is not substantially restricted by the outdoor metering device 120. Refrigerant generally exits the outdoor metering device 120 and flows to the indoor metering device 112, which may meter the flow of refrigerant through the indoor metering device 112, such 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. From the indoor metering device 112, the two-phase refrigerant may enter the indoor heat exchanger 108. As the refrigerant is passed through the indoor heat exchanger 108, heat may be transferred to the refrigerant from an airflow that is passed through and/or into contact with the indoor heat exchanger 108 by the indoor fan 110, thereby causing evaporation of the liquid-phase portion of the two-phase refrigerant mixture. The refrigerant may exit the indoor heat exchanger 108 and flow to the first variable port 130 of the reversing valve 122. In the cooling mode, the reversing valve 122 may be selectively configured to divert the refrigerant back to the compressor 116 through the main outlet port 132. At the compressor 116, the compressor 116 may increase the pressure of the refrigerant and the refrigeration cycle may begin again.
Referring now to FIG. 2, a schematic diagram of the HVAC system 100 of FIG. 1 comprising the DSHCR system 106 of FIG. 1 is shown configured in a heating mode according to an embodiment of the disclosure. When the HVAC system 100 is operated in the heating mode, heat may generally be absorbed by refrigerant at the outdoor heat exchanger 114 and rejected from the refrigerant at the indoor heat exchanger 108. Starting at the compressor 116, the compressor 116 may similarly be operated to compress refrigerant and pump the relatively high temperature and high pressure compressed refrigerant to the inlet port 123 of the three-way valve 126. However, in a heating mode configuration, the three-way valve 126 may be selectively configured to divert the refrigerant entering the inlet port 123 to the second outlet port 128 as opposed to the first outlet port 125. Refrigerant exiting the second outlet port 128 may encounter the junction of the desuperheater heat exchanger outlet 129 and the main inlet port 136 of the reversing valve 122. Because the HVAC system 100 may be configured for operation in the heating mode, refrigerant may not enter through the first outlet port 125 of the three-way valve 126, and thus not enter the desuperheater heat exchanger 124 through the desuperheater heat exchanger outlet 129. Accordingly, the desuperheater heat exchanger 124 is effectively removed from the refrigerant fluid circuit.
As a result of removing the desuperheater heat exchanger 124 from the refrigerant fluid circuit when the HVAC system 100 is operated in a heating mode, the desuperheater heat exchanger 124 remains functionally idle with respect to refrigerant flow. However, the desuperheater heat exchanger 124 may be configured to sequester excess liquid refrigerant that is not needed for a heating operation in HVAC system 100. Therefore, the desuperheater heat exchanger 124 may perform the function of a traditional charge robber in the heating mode by sequestering excess liquid refrigerant that traditionally may backup in the indoor heat exchanger 108 and reduce the efficiency of the HVAC system 100. Additionally, as a result of the location of the desuperheater heat exchanger 124 in the refrigeration circuit, the desuperheater heat exchanger 124 and/or DSHCR system 106 may sequester excess liquid refrigerant at a location that is as far upstream from the compressor 116 as possible. Accordingly, the desuperheater heat exchanger 124 and/or the DSHCR system 106 may prevent excess liquid refrigerant that poses a potential damage risk to the compressor 116 from entering the compressor 116, thereby increasing the reliability of the compressor 116 and/or preventing damage to the compressor 116.
Additionally, by locating the desuperheater heat exchanger 124 on the high pressure side of the reversing valve 122, air passing over the desuperheater heat exchanger 124 may be below saturation temperature, which may condense refrigerant in the desuperheater heat exchanger 124 into liquid refrigerant. As such, by removing the desuperheater heat exchanger 124 from the refrigerant fluid circuit, liquid refrigerant that may condense in the desuperheater heat exchanger 124 may further be sequestered from the indoor heat exchanger 108 and/or the compressor 116. Further, in addition to increasing the cooling performance and/or efficiency of the HVAC system 100 when the HVAC system 100 is operated in the cooling mode, the desuperheater heat exchanger 124 and/or the DSHCR system 106 may improve heating performance by performing the function of a traditional charge robber by sequestering the excess liquid refrigerant without the additional cost and complexity of adding a traditional charge robbing system.
Refrigerant exiting the three-way valve 126 through the second outlet port 128 may thus enter the reversing valve 122 through the main inlet port 136. In a heating mode configuration, the reversing valve 122 may be selectively configured to divert the refrigerant entering the main inlet port 136 to the first variable port 130 as opposed to the second variable port 134 during operation of the HVAC system 100 in a cooling mode. Refrigerant may exit the reversing valve 122 through the first variable port 130 and flow to the indoor heat exchanger 108. By diverting the incoming flow to the first variable port 130 and to the indoor heat exchanger 108 prior to the outdoor heat exchanger 114, it will be appreciated that refrigerant flow through the HVAC system 100 is effectively reversed.
The high temperature refrigerant may then flow to the indoor heat exchanger 108 where it may transfer heat to an airflow that is passed through and/or into contact with the indoor heat exchanger 108. After exiting the indoor heat exchanger 108, the refrigerant may flow through and/or bypass the indoor metering device 112, such that refrigerant flow is not substantially restricted by the indoor metering device 112. Refrigerant generally exits the indoor metering device 112 and flows to the outdoor metering device 120, which may meter the flow of refrigerant through the outdoor metering device 120, such that the refrigerant downstream of the outdoor metering device 120 is at a lower pressure than the refrigerant upstream of the outdoor metering device 120. From the outdoor metering device 120, the refrigerant may enter the outdoor heat exchanger 114. As the refrigerant is passed through the outdoor heat exchanger 114, heat may be transferred to the refrigerant from an airflow that is passed through and/or into contact with the outdoor heat exchanger 114 by the outdoor fan 118. Refrigerant leaving the outdoor heat exchanger 114 may enter the second variable port 134 of the reversing valve 122, where the reversing valve 122 may be selectively configured to divert the refrigerant to the main outlet port 132 and consequently back to the compressor 116, where the refrigeration cycle may begin again.
Referring now to FIG. 3, a schematic diagram of an HVAC system 200 comprising a DSHCR system 206 is shown configured in a cooling mode according to another embodiment of the disclosure. Most generally, HVAC system 200 may comprise a heat pump system and be substantially similar to HVAC system 100 of FIGS. 1-2 in that HVAC system 200 generally comprises an indoor unit 202 and an outdoor unit 204. Accordingly, indoor unit 202 may be substantially similar to indoor unit 102 and generally comprises an indoor heat exchanger 208, an indoor fan 210, and an indoor metering device 212. Further, outdoor unit 204 may be substantially similar to outdoor unit 104 and generally comprises an outdoor heat exchanger 214, a compressor 216, an outdoor fan 218, and an outdoor metering device 220. However, outdoor unit 204 comprises an alternatively-configured DSHCR system 206. Further, it will be appreciated that while the reversing valve 222 may generally be associated with the outdoor unit 204, the reversing valve 222 may be described as being a component of the DSHCR system 206, since operation of the DSHCR system 206 relies heavily on the operation of the reversing valve 222. It will also be appreciated that, although not pictured, the HVAC system 200 may also comprise a system controller that is configured to generally communicate with an indoor controller of the indoor unit 202 and/or an outdoor controller of the outdoor unit 204 and/or control operation of the indoor unit 202 and/or the outdoor unit 204. Additionally, the system controller may comprise a temperature sensor and may further be configured to control heating and/or cooling of zones associated with the HVAC system 200.
DSHCR system 206 may be substantially similar to DSHCR system 106 and generally comprises a reversing valve 222 and a desuperheater heat exchanger 224. As opposed to the four-way reversing valve 122 used in DSHCR 106, reversing valve 222 may generally comprise a five-way reversing valve that may be substantially similar to the five-way reversing valve disclosed in U.S. patent application Ser. No. 14/720,170, filed on May 22, 2015 by Hancock and entitled “Five-Way Heat Pump Reversing Valve,” the disclosure of which is hereby incorporated by reference in its entirety. In some embodiments, the five-way reversing valve 222 may provide additional functionality that may eliminate the need for additional components, i.e. three-way valve 126 used in DSHCR 106 in FIGS. 1-2. The five-way reversing valve 222 comprises a first inlet port 236, a second inlet port 238, a first variable port 230, a main outlet port 232, and a second variable port 234. As will be discussed later herein, the reversing valve 222 may generally be selectively controlled to alter a flowpath of refrigerant in the HVAC system 200 by selectively altering a refrigerant flowpath through the first inlet port 236, the second inlet port 238, the first variable port 230, the main outlet port 232, and the second variable port 234. The reversing valve 222 may also comprise an electrical solenoid, relay, and/or other device configured to selectively move a component of the reversing valve 222 between operational positions to alter the flowpaths through the reversing valve 222 and consequently the HVAC system 200. Additionally, the reversing valve 222 may be selectively controlled by a system controller and/or an outdoor controller.
The desuperheater heat exchanger 224 may generally be described as comprising a desuperheater inlet 227 and a desuperheater outlet 229. The desuperheater inlet 227 may generally be selectively connected in fluid communication with a discharge side of the compressor 216 and the first inlet port 236 of the reversing valve 222, while the desuperheater outlet 229 may be connected in fluid communication with the second inlet port 238 of the reversing valve 222. When the HVAC system 200 is operated in the cooling mode, the desuperheater heat exchanger 224 may generally be configured to promote heat transfer between a refrigerant carried within internal passages of the desuperheater heat exchanger 224 and an airflow that contacts the desuperheater heat exchanger 224 but that is segregated from the refrigerant. However, when the HVAC system 200 is operated in the heating mode, the desuperheater heat exchanger 224 may perform the function of a traditional charge robber to store excess liquid refrigerant. In some embodiments, desuperheater heat exchanger 224 may comprise a plate-fin heat exchanger. However, in other embodiments, desuperheater heat exchanger 224 may comprise a spine fin heat exchanger, a microchannel heat exchanger, or any other suitable type of heat exchanger.
Still referring to FIG. 3, the HVAC system 200 is shown configured for operating in a cooling mode. When the HVAC system 200 is operated in the cooling mode, heat may generally be absorbed by refrigerant at the indoor heat exchanger 208 and rejected from the refrigerant at the outdoor heat exchanger 214 and/or the desuperheater heat exchanger 224. Starting at the compressor 216, the compressor 216 may be operated to compress refrigerant and pump the relatively high temperature and high pressure refrigerant to the desuperheater inlet 227. In this embodiment, and when the HVAC system 200 is operated in the cooling mode, the reversing valve 222 may be configured such that refrigerant flow from the compressor 216 does not enter the first inlet port 236 of the reversing valve 222 and flow through the reversing valve 222. The compressor 216 instead delivers refrigerant to the desuperheater heat exchanger 224 through the desuperheater heat exchanger inlet 227, where the refrigerant may flow through the desuperheater heat exchanger 224.
Within the desuperheater heat exchanger 224, the relatively high temperature refrigerant may transfer heat to an airflow passed through and/or into contact with the desuperheater heat exchanger 224 by the outdoor fan 218. After passing through the desuperheater heat exchanger 224, refrigerant may exit the desuperheater heat exchanger 224 through the desuperheater outlet 229 and flow to the second inlet port 238 of the reversing valve 222. The reversing valve 222 may be configured to allow refrigerant to enter the reversing valve 222 through the second inlet port 238, flow through the reversing valve 222, and exit the reversing valve 222 through the second variable port 234. In some embodiments, when the HVAC system 200 is configured in the cooling mode of operation, the flowpath through the reversing valve 222 from the second inlet port 238 to the second variable port 234 may comprise a substantially straight, linear flowpath, which may, in some embodiments, reduce a pressure drop through the reversing valve 222 and/or provide an increase in efficiency of the HVAC system 200 over a reversing valve 222 having a substantially non-linear flowpath.
Refrigerant exiting the reversing valve 222 through the second variable port 234 may flow to the outdoor heat exchanger 214, where the refrigerant may transfer additional heat to the airflow that is passed through and/or into contact with the outdoor heat exchanger 214 by the outdoor fan 218, thereby condensing to a subcooled liquid-phase refrigerant before exiting the outdoor heat exchanger 214 and flowing to the outdoor metering device 220. By passing the heated refrigerant through the desuperheater heat exchanger 224 prior to passing the refrigerant through the outdoor heat exchanger 214 and by contacting the outdoor heat exchanger 214 with an ambient airflow generated by the outdoor fan 218 prior to the heated airflow encountering the relatively higher temperature desuperheater heat exchanger 224, the temperature differentials between the airflow generated by the outdoor fan 218 and the respective heat exchangers 224, 214 may be maximized. Accordingly, the desuperheater heat exchanger 224 and/or the DSHCR system 206 may increase the cooling performance and/or the efficiency of the HVAC system 200 as compared to a traditional system that may not comprise a desuperheater heat exchanger 224 and/or a DSHCR system 206.
After exiting the outdoor heat exchanger 214, the refrigerant may flow through and/or bypass the outdoor metering device 220, such that refrigerant flow is not substantially restricted by the outdoor metering device 220. Refrigerant generally exits the outdoor metering device 220 and flows to the indoor metering device 212, which may meter the flow of refrigerant through the indoor metering device 212, such that the refrigerant downstream of the indoor metering device 212 is at a lower pressure than the refrigerant upstream of the indoor metering device 212. The pressure differential across the indoor metering device 212 allows the refrigerant downstream of the indoor metering device 212 to expand and/or at least partially convert to a two-phase (vapor and gas) mixture. From the indoor metering device 212, the two-phase refrigerant may enter the indoor heat exchanger 208. As the refrigerant is passed through the indoor heat exchanger 208, heat may be transferred to the refrigerant from an airflow that is passed through and/or into contact with the indoor heat exchanger 208 by the indoor fan 210, thereby causing evaporation of the liquid-phase portion of the two-phase refrigerant mixture. The refrigerant may exit the indoor heat exchanger 208 and flow to the first variable port 230 of the reversing valve 222. In the cooling mode, the reversing valve 222 may be selectively configured to divert the refrigerant back to the compressor 216 through the main outlet port 232. At the compressor 216, the compressor 216 may again increase the pressure of the refrigerant and the refrigeration cycle may begin again.
Referring now to FIG. 4, a schematic diagram of the HVAC system 200 of FIG. 3 comprising the DSHCR system 206 of FIG. 3 is shown configured in a heating mode according to another embodiment of the disclosure. When the HVAC system 200 is operated in the heating mode, heat may generally be absorbed by refrigerant at the outdoor heat exchanger 214 and rejected from the refrigerant at the indoor heat exchanger 208. Starting at the compressor 216, the compressor 216 may similarly be operated to compress refrigerant and pump the relatively high temperature and high pressure compressed refrigerant to the first inlet port 236 of the reversing valve 222. While the discharge of the compressor 216 remains in fluid communication with the desuperheater heat exchanger 224, the reversing valve 222 may be selectively configured to prevent refrigerant from passing through the reversing valve 222 via the second inlet port 238. As a result, substantially no refrigerant passes through the desuperheater heat exchanger 224 during operation of the HVAC system 200 in the heating mode. Thus, when the HVAC system 200 is operated in the heating mode, the desuperheater heat exchanger 224 remains functionally idle with respect to refrigerant flow. However, the desuperheater heat exchanger 224 may be configured to sequester excess refrigerant that is not needed for a heating operation in HVAC system 200. Therefore, the desuperheater heat exchanger 224 may perform the function of a traditional charge robber in the heating mode by sequestering excess liquid refrigerant that traditionally may backup in the indoor heat exchanger 208 and reduce the efficiency of the HVAC system 200.
Additionally, as a result of the location of the desuperheater heat exchanger 224 in the refrigeration circuit, the desuperheater heat exchanger 224 and/or DSHCR system 206 may sequester excess liquid refrigerant at a location that is as far upstream from the compressor 216 as possible. Accordingly, the desuperheater heat exchanger 224 and/or the DSHCR system 206 may prevent excess liquid refrigerant that poses a potential damage risk to the compressor 216 from entering the compressor 216, thereby increasing the reliability of the compressor 216 and/or preventing damage to the compressor 216. Further, in addition to increasing the cooling performance and/or efficiency of the HVAC system 200 when the HVAC system 200 is operated in the cooling mode, the desuperheater heat exchanger 224 and/or the DSHCR system 206 may improve heating performance by performing the function of a traditional charge robber by sequestering the excess liquid refrigerant without the additional cost and complexity of adding a traditional charge robbing system.
Continuing through the heating cycle, refrigerant entering the first inlet port 236 of the reversing valve 222 may flow through the reversing valve 222 and exit the reversing valve 222 via the first variable port 230. The high temperature refrigerant may then flow to the indoor heat exchanger 208 where it may transfer heat to an airflow that is passed through and/or into contact with the indoor heat exchanger 208 by the indoor fan 210. After exiting the indoor heat exchanger 208, the refrigerant may flow through and/or bypass the indoor metering device 212, such that refrigerant flow is not substantially restricted by the indoor metering device 212. Refrigerant generally exits the indoor metering device 212 and flows to the outdoor metering device 220, which may meter the flow of refrigerant through the outdoor metering device 220, such that the refrigerant downstream of the outdoor metering device 220 is at a lower pressure than the refrigerant upstream of the outdoor metering device 220. From the outdoor metering device 220, the refrigerant may enter the outdoor heat exchanger 214. As the refrigerant is passed through the outdoor heat exchanger 214, heat may be transferred to the refrigerant from an airflow that is passed through and/or into contact with the outdoor heat exchanger 214 by the outdoor fan 218. Refrigerant leaving the outdoor heat exchanger 214 may flow to the second variable port 234 of the reversing valve 222, where the reversing valve 222 may be selectively configured to divert the refrigerant to exit the reversing valve 222 through the main outlet port 232 and consequently back to the compressor 216, where the refrigeration cycle may begin again.
Referring now to FIG. 5, a flowchart of a method 300 of operating an HVAC system is shown according to an embodiment of the disclosure. The method 300 may begin at block 302 by flowing refrigerant through a desuperheater heat exchanger. In some embodiments, flowing refrigerant through the desuperheater heat exchanger may be accomplished by operating the HVAC system in a cooling mode. In some embodiments, the desuperheater heat exchanger may comprise desuperheater heat exchanger 124 of FIGS. 1-2. In other embodiments, the desuperheater heat exchanger may comprise desuperheater heat exchanger 224 of FIGS. 3-4. The method 300 may continue at block 304 by switching the HVAC system from the cooling mode to a heating mode. The method 300 may conclude at block 306 by preventing refrigerant from flowing through the desuperheater heat exchanger when the HVAC system is operated in the heating mode. In some embodiments, this may be accomplished by configuring components of a DSHCR 106, 206 to remove the desuperheater heat exchanger from the refrigerant fluid circuit.
Referring now to FIG. 6, a flowchart of a method 400 of operating an HVAC system is shown according to another embodiment of the disclosure. The method may begin at block 402 by selecting a mode of operation of the HVAC system. If a cooling mode of operation is selected, the method 400 may continue at block 404. At block 404, a five-way reversing valve may be selectively configured to allow the flow of refrigerant through a desuperheater heat exchanger. However, if a heating mode of operation is selected at block 402, the method 400 may continue to block 406. At block 406, the five-way reversing valve may be selectively configured to restrict and/or prevent the flow of refrigerant through the desuperheater heat exchanger. In some embodiments, at block 406, when refrigerant flow through the desuperheater heat exchanger is restricted, the desuperheater heat exchanger may still remain in fluid communication with a high pressure side of the refrigerant fluid circuit. More specifically, in some embodiments, the desuperheater heat exchanger may still remain in fluid communication with a discharge side of a compressor of the HVAC system.
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_l, 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=R₁−k*(R_u−R_l), 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.

Claims

What is claimed is:

1. A heating, ventilation, and/or air-conditioning (HVAC) system, comprising:

a desuperheater/charge robber (DSHCR) system configured to (1) selectively allow a flow of refrigerant through a desuperheater heat exchanger when the HVAC system is operated in a cooling mode and (2) selectively prevent the flow of refrigerant through the desuperheater heat exchanger from a refrigerant fluid circuit while keeping the desuperheater heat exchanger in fluid communication with a high pressure side of the refrigerant fluid circuit when the HVAC system is operated in a heating mode.

2. The HVAC system of claim 1, further comprising:

a three-way valve.

3. The HVAC system of claim 2, wherein the three-way valve is configured to divert refrigerant to the desuperheater heat exchanger when the HVAC system is operated in the cooling mode.

4. The HVAC system of claim 2, wherein the three-way valve is configured to divert refrigerant to flow to the reversing valve when the HVAC system is operated in the heating mode.

5. The HVAC system of claim 2, wherein the three-way valve is configured to prevent refrigerant from flowing through the desuperheater heat exchanger when the HVAC system is configured in the heating mode.

6. The HVAC system of claim 1, wherein the desuperheater heat exchanger is configured to promote heat exchange between the refrigerant and an airflow generated by an outdoor fan of the HVAC system when the HVAC system is operated in the cooling mode.

7. The HVAC system of claim 1, wherein the desuperheater heat exchanger is configured to sequester at least a portion of the refrigerant when the HVAC system is operated in the heating mode.

8. The HVAC system of claim 1, further comprising:

a four-way reversing valve.

9. The HVAC system of claim 8, wherein the desuperheater heat exchanger is configured to deliver refrigerant to the reversing valve of the HVAC system when the HVAC system is operated in the cooling mode.

10. The HVAC system of claim 8, wherein the four-way reversing valve is configured to reverse the flow of refrigerant through at least one of an indoor heat exchanger of the HVAC system and an outdoor heat exchanger of the HVAC system.

11. The HVAC system of claim 1, further comprising:

a five-way reversing valve.

12. The HVAC system of claim 11, wherein the five-way reversing valve is configured to reverse the flow of refrigerant through at least one of an indoor heat exchanger of the HVAC system and an outdoor heat exchanger of the HVAC system.

13. The HVAC system of claim 11, wherein the five-way reversing valve is configured to allow refrigerant to flow through the desuperheater heat exchanger when the HVAC system is configured in a cooling mode.

14. The HVAC system of claim 11, wherein the five-way reversing valve is configured to prevent refrigerant from flowing through the desuperheater heat exchanger when the HVAC system is configured in a heating mode.

15. The HVAC system of claim 1, wherein the HVAC system is configured as a heat pump HVAC system.

16. A method of operating a heating, ventilation, and/or air-conditioning (HVAC) system, comprising:

flowing refrigerant through a desuperheater heat exchanger when the HVAC system is operated in a cooling mode;

switching the HVAC system from the cooling mode to a heating mode; and

preventing refrigerant from flowing through the desuperheater heat exchanger while keeping the desuperheater heat exchanger in fluid communication with a high pressure side of a refrigerant fluid circuit when the HVAC system is operated in the heating mode.

17. The method of claim 16, further comprising:

storing at least a portion of the refrigerant in the desuperheater heat exchanger when the HVAC system is operated in the heating mode.

18. The method of claim 16, wherein the switching the HVAC system from the cooling mode to a heating mode is accomplished by selectively configuring at least one of a three-way reversing valve, a four-way reversing valve, and a five-way reversing valve.

19. The method of claim 16, wherein the preventing refrigerant from flowing through the desuperheater heat exchanger is accomplished by selectively configuring a three-way reversing valve and a four-way reversing valve to remove the desuperheater heat exchanger from a refrigerant fluid circuit.

20. The method of claim 16, wherein the preventing refrigerant from flowing through the desuperheater heat exchanger is accomplished by selectively configuring a five-way reversing valve to remove the desuperheater heat exchanger from a refrigerant fluid circuit.