Patent ID: 12215884

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that 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.

When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

As used herein, the terms “approximately,” “generally,” and “substantially,” and so forth, are intended to convey that the property value being described may be within a relatively small range of the property value, as those of ordinary skill would understand. For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to) a given value, this is intended to mean that the property value may be within +/−5%, within +/−4%, within +/−3%, within +/−2%, within +/−1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” to another feature, “generally perpendicular” to another feature, and so forth, this is intended to mean that the given feature is within +/−5%, within +/−4%, within +/−3%, within +/−2%, within +/−1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular to another feature, and so forth. Further, it should be understood that mathematical terms, such as “planar,” “slope,” “perpendicular,” “parallel,” and so forth are intended to encompass features of surfaces or elements as understood to one of ordinary skill in the relevant art, and should not be rigidly interpreted as might be understood in the mathematical arts. For example, a “planar” surface is intended to encompass a surface that is machined, molded, or otherwise formed to be substantially flat or smooth (within related tolerances) using techniques and tools available to one of ordinary skill in the art. Similarly, a surface having a “slope” is intended to encompass a surface that is machined, molded, or otherwise formed to be oriented at an angle (e.g., incline) with respect to a point of reference using techniques and tools available to one of ordinary skill in the art.

As briefly discussed above, a heating, ventilation, and/or air conditioning (HVAC) system may be used to thermally regulate a space within a building, home, or other suitable structure. For example, the HVAC system may include a vapor compression system that transfers thermal energy between a working fluid, such as a refrigerant, and a fluid to be conditioned, such as air. The vapor compression system includes heat exchangers, such as a condenser and an evaporator, which are fluidly coupled to one another via one or more conduits of a working fluid loop or circuit (e.g., refrigerant circuit). A compressor may be used to circulate the working fluid through the conduits and other components of the working fluid circuit (e.g., an expansion device) and, thus, enable the transfer of thermal energy between components of the working fluid circuit (e.g., between the condenser and the evaporator) and one or more thermal loads (e.g., an environmental air flow, a supply air flow). Additionally or alternatively, the HVAC system may include a heat pump (e.g., a heat pump system) having a first heat exchanger (e.g., a heating and/or cooling coil, an indoor coil, the evaporator) positioned within the space to be conditioned, a second heat exchanger (e.g., a heating and/or cooling coil, an outdoor coil, the condenser) positioned in or otherwise fluidly coupled to an ambient environment (e.g., the atmosphere), and a pump (e.g., the compressor) configured to circulate the working fluid (e.g., refrigerant) between the first and second heat exchangers to enable heat transfer between the thermal load (e.g., an air flow to be conditioned) and the ambient environment, for example. The heat pump system is operable to provide both cooling and heating to the space to be conditioned (e.g., a room, zone, or other region within a building) by adjusting a flow of the working fluid through the working fluid circuit. Thus, the heat pump may not include a dedicated heating system, such as a furnace or burner configured to combust a fuel, to enable operation of the HVAC system in the heating mode. As a result, the heat pump is configured to operate with reduced greenhouse gas emissions.

For example, during operation of the heat pump system in a cooling mode, the compressor may direct working fluid through the working fluid circuit and the first and second heat exchangers in a first flow direction. While receiving working fluid in the first flow direction, the first heat exchanger (which may be positioned within the space to be conditioned) may operate as an evaporator and, thus, enable working fluid flowing through the first heat exchanger to absorb thermal energy from an air flow directed to the space. Further, the second heat exchanger (which may be positioned in the ambient environment surrounding the heat pump system) may operate as a condenser to reject the heat absorbed by the working fluid flowing from the first heat exchanger (e.g., to an ambient air flow directed across the second heat exchanger). In this way, the heat pump system may facilitate cooling of the space or other thermal load serviced by (e.g., in thermal communication with) the first heat exchanger.

Conversely, during operation in a heating mode, a reversing valve (e.g., a switch-over valve) enables the compressor to direct working fluid through the working fluid circuit and the first and second heat exchangers in a second flow direction, opposite the first flow direction. While receiving working fluid in the second flow direction, the first heat exchanger may operate as a condenser instead of an evaporator, and the second heat exchanger may operate as an evaporator instead of a condenser. As such, the first heat exchanger may receive (e.g., from the second heat exchanger) a flow of heated working fluid to reject heat to thermal load serviced by the first heat exchanger (e.g., an air flow directed to the space) and, thus, facilitate heating of the thermal load. In this way, the heat pump system may facilitate either heating or cooling of the thermal load based on the current operational mode of the heat pump system (e.g., based on a flow direction of working fluid along the working fluid circuit).

Unfortunately, heat pumps may be susceptible to operational efficiencies in certain conditions or circumstances. For example, in many cases, pressure differentials or pressure ratios across various components (e.g., the compressor) or sections of the working fluid circuit may vary based on the mode (e.g., cooling, heating) in which the heat pump system operates. As an example, pressure ratios across the compressor of the working fluid circuit may be relatively small while the heat pump system operates in the cooling mode and may be relatively large while the heat pump system operates in the heating mode. Such pressure ratios may be indicative of a differential between an entering working fluid pressure at an inlet of the compressor and an exiting working fluid pressure at an outlet of the compressor. Compressors in existing heat pump systems may operate inefficiently at varying pressure differentials that may be encountered between operation in the cooling and heating modes of the heat pump system.

In some cases, certain compressors may be ill-suited and/or inefficient for certain HVAC system applications or conditions (e.g., based on amounts of heating and cooling typically desired in a particular HVAC system application). For example, a heating load of a heat pump may be greater in a cold climate than in a warm climate, but a cooling load of the heat pump in the same cold climate may be lower. In such applications, the heat pump may include a compressor that operates inadequately or inefficiently in a heating mode to satisfy a greater heating demand in the cold climate, but the compressor may operate adequately in a cooling mode. Alternatively, some heat pumps utilized in a cold climate may operate adequately in the heating mode but may operate inefficiently in the cooling mode.

Conventional approaches to address such shortcomings with heat pumps are typically expensive and complicated. Conventional approaches may also be associated with increased energy consumption and generation of greenhouse gas emissions. For example, in cold climate implementations, heat pumps may be implemented with auxiliary heating systems, such as electric heating systems or fuel combustion heating systems (e.g., furnaces), which add costs to the manufacture, maintenance, and operation of the HVAC system. Moreover, utilization of auxiliary heating systems, such as furnaces, generally results in the undesirable generation of greenhouse gas emissions. Other approaches include the incorporation of subcoolers, flash tanks, and/or other components with heat pumps, which also add manufacture, maintenance, and operation costs associated with the HVAC system. For at least the foregoing reasons, conventional HVAC systems utilizing heat pumps, particularly in cold climate environments, are inefficient, expensive, and/or susceptible to increased emissions. It is presently recognized that improved heat pump systems that mitigate or substantially eliminate the aforementioned shortcomings of conventional HVAC systems are desired.

Accordingly, embodiments of the present disclosure relate to a heat pump system that is configured to enable more efficient operation (e.g., in cold climate environments), enable reduction in costs associated with manufacturing, operating, and maintaining an HVAC system, and enable a reduction in the generation of greenhouse gas emissions. For example, present embodiments include energy efficient heat pump systems configured to operate in cold climate environments to satisfy heating demands without utilization of an auxiliary heating system, such as a furnace. In this way, the present techniques enable a reduction in energy consumption and a reduction in greenhouse gas emissions. As discussed in detail below, the heat pump system (e.g., reverse-cycle heat pump system, energy efficient heat pump) may include a compressor having an injection port (e.g., intermediate injection port) configured to receive a flow of vapor and/or liquid at an intermediate portion of the compressor (e.g., between a suction port and a discharge port of the compressor). In other words, the compressor is configured to receive a flow (e.g., a first flow, main flow) of working fluid (e.g., refrigerant) from the working fluid circuit (e.g., from a heat exchanger) of the heat pump system, and the compressor is also configured to receive a flow (e.g., a second flow, additional flow) of vapor and/or liquid working fluid via the injection port.

In accordance with present techniques, the flow of vapor and/or liquid directed to the injection port of the compressor may be directed from a section of the working fluid circuit different from a section of the working fluid circuit extending to a suction port of the compressor. As discussed above, the working fluid circuit may be configured to direct a flow of working fluid from the first heat exchanger to the second heat exchanger in one operating mode (e.g., cooling) and from the second heat exchanger to the first heat exchanger in another operating mode (e.g., heating). A portion of the flow of working fluid (e.g., liquid working fluid) may be directed from the working fluid circuit at a location between the first and second heat exchangers (e.g., a liquid line location) to an injection conduit extending from the location to the injection port of the compressor. An expansion device may be disposed along the injection conduit and may expand or “flash” the portion of the flow of working fluid to produce a vapor working fluid or a vapor and liquid mixture of working fluid. The portion of the flow of working fluid may then be injected into the compressor for compression with working fluid received by the compressor via the suction port of the compressor.

By injecting working fluid into the injection port of the compressor at an intermediate location of the compressor (e.g., between the suction port and the discharge port), various improvements and benefits may be provided. For example, the injected flow of working fluid may provide cooling to the compressor, which may enable more efficient operation of the compressor (e.g., reduced energy consumption). Cooling of the compressor via the injected flow of working fluid may also provide decreased working fluid discharge temperatures, which may extend an operating range of the compressor without adverse impact to an operating life (e.g., useful life) of the compressor. Additionally, by injecting working fluid into the compressor via the injection port and combining the injected working fluid with working fluid received via the suction port of the compressor, a mass flow rate of working fluid discharged by the compressor may be increased, which may increase an operating capacity of the particular heat exchanger that receives the discharged working fluid from the compressor in a particular operating mode of the heat pump system. The flow of working fluid injected into the compressor via the injection port may be controlled based on different variables and/or operating parameters of the heat pump system, as discussed in further detail below. Moreover, the present techniques enable injection of working fluid into the compressor in a desirable manner at significantly reduced costs (e.g., manufacturing costs, operating costs, maintenance costs). Thus, the present techniques enable improved operation and manufacture of heat pumps systems. Indeed, the present embodiments provide energy efficient heat pumps configured to operate and satisfy heating demands in cold climate conditions with reduced energy consumption and without operation of a furnace or other heating system configured to combust or consume a fuel, thereby enabling a reduction of greenhouse gas emissions.

It should be understood that one or more of the compressors included in the heat pump system may be fixed speed compressors, multi-stage (e.g., two stage) compressors, and/or variable speed compressors. Additionally, the present techniques may be incorporated with heat pump systems utilizing different types of compressors, such as rotary compressors, screw compressors, scroll compressors, and so forth. These and other features will be described below with reference to the drawings.

Turning now to the drawings,FIG.1illustrates an embodiment of a heating, ventilation, and/or air conditioning (HVAC) system for environmental management that employs one or more HVAC units in accordance with the present disclosure. As used herein, an HVAC system includes any number of components configured to enable regulation of parameters related to climate characteristics, such as temperature, humidity, air flow, pressure, air quality, and so forth. For example, an “HVAC system” as used herein is defined as conventionally understood and as further described herein. Components or parts of an “HVAC system” may include, but are not limited to, all, some of, or individual parts such as a heat exchanger, a heater, an air flow control device, such as a fan, a sensor configured to detect a climate characteristic or operating parameter, a filter, a control device configured to regulate operation of an HVAC system component, a component configured to enable regulation of climate characteristics, or a combination thereof. An “HVAC system” is a system configured to provide such functions as heating, cooling, ventilation, dehumidification, pressurization, refrigeration, filtration, or any combination thereof. The embodiments described herein may be utilized in a variety of applications to control climate characteristics, such as residential, commercial, industrial, transportation, or other applications where climate control is desired.

In the illustrated embodiment, a building10is air conditioned by a system that includes an HVAC unit12in accordance with present embodiments. The building10may be a commercial structure or a residential structure. As shown, the HVAC unit12is disposed on the roof of the building10; however, the HVAC unit12may be located in other equipment rooms or areas adjacent the building10. The HVAC unit12may be a single package unit containing other equipment, such as a blower and/or integrated air handler. In other embodiments, the HVAC unit12may be part of a split HVAC system, such as the system shown inFIG.3, which includes an outdoor HVAC unit58and an indoor HVAC unit56.

The HVAC unit12is an air-cooled device that implements a refrigeration cycle to provide conditioned air to the building10. Specifically, the HVAC unit12may include one or more heat exchangers across which an air flow is passed to condition the air flow before the air flow is supplied to the building. In the illustrated embodiment, the HVAC unit12is a rooftop unit (RTU) that conditions a supply air flow, such as environmental air and/or a return air flow from the building10. After the HVAC unit12conditions the air, the air is supplied to the building10via ductwork14extending throughout the building10from the HVAC unit12. For example, the ductwork14may extend to various individual floors or other sections of the building10. In certain embodiments, the HVAC unit12may be a heat pump that provides both heating and cooling to the building with one refrigeration circuit configured to operate in different modes.

A control device16, one type of which may be a thermostat, may be used to designate the temperature of the conditioned air. The control device16also may be used to control the flow of air through the ductwork14. For example, the control device16may be used to regulate operation of one or more components of the HVAC unit12or other components, such as dampers and fans, within the building10that may control flow of air through and/or from the ductwork14. In some embodiments, other devices may be included in the system, such as pressure and/or temperature transducers or switches that sense the temperatures and pressures of the supply air, return air, and so forth. Moreover, the control device16may include computer systems that are integrated with or separate from other building control or monitoring systems, and even systems that are remote from the building10.

FIG.2is a perspective view of an embodiment of the HVAC unit12. In the illustrated embodiment, the HVAC unit12is a single package unit that may include one or more independent working fluid circuits and components that are tested, charged, wired, piped, and ready for installation. The HVAC unit12may provide a variety of heating and/or cooling functions, such as cooling only, heating only, cooling with dehumidification, heating with a heat pump, and/or cooling with a heat pump. As described above, the HVAC unit12may directly cool and/or heat an air flow provided to the building10to condition a space in the building10.

As shown in the illustrated embodiment ofFIG.2, a cabinet24encloses the HVAC unit12and provides structural support and protection to the internal components from environmental and other contaminants. In some embodiments, the cabinet24may be constructed of galvanized steel and insulated with aluminum foil faced insulation. Rails26may be joined to the bottom perimeter of the cabinet24and provide a foundation for the HVAC unit12. In certain embodiments, the rails26may provide access for a forklift and/or overhead rigging to facilitate installation and/or removal of the HVAC unit12. In some embodiments, the rails26may fit into “curbs” on the roof to enable the HVAC unit12to provide air to the ductwork14from the bottom of the HVAC unit12while blocking elements such as rain from leaking into the building10.

The HVAC unit12includes heat exchangers28and30in fluid communication with one or more working fluid circuits. Tubes within the heat exchangers28and30may circulate a working fluid (e.g., refrigerant), such as R-454B and/or R32, through the heat exchangers28and30. The tubes may be of various types, such as multichannel tubes, conventional copper or aluminum tubing, and so forth. Together, the heat exchangers28and30may implement a thermal cycle in which the working fluid undergoes phase changes and/or temperature changes as it flows through the heat exchangers28and30to produce heated and/or cooled air. For example, the heat exchanger28may function as a condenser where heat is released from the working fluid to ambient air, and the heat exchanger30may function as an evaporator where the working fluid absorbs heat to cool an air flow. In some embodiments, the HVAC unit12may operate in a heat pump mode where the roles of the heat exchangers28and30may be reversed. That is, the heat exchanger28may function as an evaporator and the heat exchanger30may function as a condenser. While the illustrated embodiment ofFIG.2shows the HVAC unit12having two of the heat exchangers28and30, in other embodiments, the HVAC unit12may include one heat exchanger or more than two heat exchangers.

The heat exchanger30is located within a compartment31that separates the heat exchanger30from the heat exchanger28. Fans32draw air from the environment through the heat exchanger28. Air may be heated and/or cooled as the air flows through the heat exchanger28before being released back to the environment surrounding the HVAC unit12. A blower assembly34, powered by a motor36, draws air through the heat exchanger30to heat or cool the air. The heated or cooled air may be directed to the building10by the ductwork14, which may be connected to the HVAC unit12. Before flowing through the heat exchanger30, the conditioned air flows through one or more filters38that may remove particulates and contaminants from the air. In certain embodiments, the filters38may be disposed on the air intake side of the heat exchanger30to prevent contaminants from contacting the heat exchanger30.

The HVAC unit12also may include other equipment for implementing the thermal cycle. Compressors42increase the pressure and temperature of the working fluid before the working fluid enters the heat exchanger28. The compressors42may be any suitable type of compressors, such as scroll compressors, rotary compressors, screw compressors, or reciprocating compressors. In some embodiments, the compressors42may include a pair of hermetic direct drive compressors arranged in a dual stage configuration44. However, in other embodiments, any number of the compressors42may be provided to achieve various stages of heating and/or cooling. As may be appreciated, additional equipment and devices may be included in the HVAC unit12, such as a solid-core filter drier, a drain pan, a disconnect switch, an economizer, pressure switches, phase monitors, and humidity sensors, among other components.

The HVAC unit12may receive power through a terminal block46. For example, a high voltage power source may be connected to the terminal block46to power the equipment. The operation of the HVAC unit12may be governed or regulated by a control board48. The control board48may include control circuitry connected to a thermostat, sensors, and alarms. One or more of these components may be referred to herein separately or collectively as the control device16. The control circuitry may be configured to control operation of the equipment, provide alarms, and monitor safety switches. Wiring49may connect the control board48and the terminal block46to the equipment of the HVAC unit12.

FIG.3illustrates a residential heating and cooling system50, also in accordance with present techniques. The residential heating and cooling system50may provide heated and cooled air to a residential structure, as well as provide outside air for ventilation and provide improved indoor air quality (IAQ) through devices such as ultraviolet lights and air filters. In the illustrated embodiment, the residential heating and cooling system50is a split HVAC system. In general, a residence52conditioned by a split HVAC system may include working fluid conduits54(e.g., refrigerant conduits) that operatively couple the indoor unit56to the outdoor unit58. The indoor unit56may be positioned in a utility room, an attic, a basement, and so forth. The outdoor unit58is typically situated adjacent to a side of residence52and is covered by a shroud to protect the system components and to prevent leaves and other debris or contaminants from entering the unit. The working fluid conduits54transfer working fluid between the indoor unit56and the outdoor unit58, typically transferring primarily liquid working fluid in one direction and primarily vaporized working fluid in an opposite direction.

When the system shown inFIG.3is operating as an air conditioner, a heat exchanger60in the outdoor unit58serves as a condenser for re-condensing vaporized working fluid flowing from the indoor unit56to the outdoor unit58via one of the working fluid conduits54. In these applications, a heat exchanger62of the indoor unit functions as an evaporator. Specifically, the heat exchanger62receives liquid working fluid, which may be expanded by an expansion device, and evaporates the working fluid before returning it to the outdoor unit58.

The outdoor unit58draws environmental air through the heat exchanger60using a fan64and expels the air above the outdoor unit58. When operating as an air conditioner, the air is heated by the heat exchanger60within the outdoor unit58and exits the unit at a temperature higher than it entered. The indoor unit56includes a blower or fan66that directs air through or across the indoor heat exchanger62, where the air is cooled when the system is operating in air conditioning mode. Thereafter, the air is passed through ductwork68that directs the air to the residence52. The overall system operates to maintain a desired temperature as set by a system controller. When the temperature sensed inside the residence52is higher than the set point on the thermostat, or the set point plus a small amount, the residential heating and cooling system50may become operative to refrigerate additional air for circulation through the residence52. When the temperature reaches the set point, or the set point minus a small amount, the residential heating and cooling system50may stop the refrigeration cycle temporarily.

The residential heating and cooling system50may also operate as a heat pump. When operating as a heat pump, the roles of heat exchangers60and62are reversed. That is, the heat exchanger60of the outdoor unit58will serve as an evaporator to evaporate working fluid and thereby cool air entering the outdoor unit58as the air passes over the outdoor heat exchanger60. The indoor heat exchanger62will receive a stream of air blown over it and will heat the air by condensing the working fluid.

FIG.4is an embodiment of a vapor compression system72that can be used in any of the systems described above. The vapor compression system72may circulate a working fluid through a circuit starting with a compressor74. The circuit may also include a condenser76, an expansion valve(s) or device(s)78, and an evaporator80. The vapor compression system72may further include a control panel82that has an analog to digital (A/D) converter84, a microprocessor86, a non-volatile memory88, and/or an interface board90. The control panel82and its components may function to regulate operation of the vapor compression system72based on feedback from an operator, from sensors of the vapor compression system72that detect operating conditions, and so forth.

In some embodiments, the vapor compression system72may use one or more of a variable speed drive (VSDs)92, a motor94, the compressor74, the condenser76, the expansion valve or device78, and/or the evaporator80. The motor94may drive the compressor74and may be powered by the variable speed drive (VSD)92. The VSD92receives 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 motor94. In other embodiments, the motor94may be powered directly from an AC or direct current (DC) power source. The motor94may 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.

The compressor74compresses a working fluid vapor and delivers the vapor to the condenser76through a discharge passage. In some embodiments, the compressor74may be a centrifugal compressor, a scroll compressor, a screw compressor, a rotary compressor, or any other suitable type of compressor. The working fluid vapor delivered by the compressor74to the condenser76may transfer heat to a fluid passing across the condenser76, such as ambient or environmental air96. The working fluid vapor may condense to a working fluid liquid in the condenser76as a result of thermal heat transfer with the environmental air96. The liquid working fluid from the condenser76may flow through the expansion device78to the evaporator80.

The liquid working fluid delivered to the evaporator80may absorb heat from another air flow, such as a supply air flow98provided to the building10or the residence52. For example, the supply air flow98may include ambient or environmental air, return air from a building, or a combination of the two. The liquid working fluid in the evaporator80may undergo a phase change from the liquid working fluid to a working fluid vapor. In this manner, the evaporator80may reduce the temperature of the supply air flow98via thermal heat transfer with the working fluid. Thereafter, the vapor working fluid exits the evaporator80and returns to the compressor74by a suction line to complete the cycle.

In some embodiments, the vapor compression system72may further include a reheat coil. In the illustrated embodiment, the reheat coil is represented as part of the evaporator80. The reheat coil is positioned downstream of the evaporator heat exchanger relative to the supply air flow98and may reheat the supply air flow98when the supply air flow98is overcooled to remove humidity from the supply air flow98before the supply air flow98is directed to the building10or the residence52.

It should be appreciated that any of the features described herein may be incorporated with the HVAC unit12, the residential heating and cooling system50, or other HVAC systems. Additionally, while the features disclosed herein are described in the context of embodiments that directly heat and cool a supply air flow provided to a building or other load, embodiments of the present disclosure may be applicable to other HVAC systems as well. For example, the features described herein may be applied to mechanical cooling systems, free cooling systems, chiller systems, or other heat pump or refrigeration applications.

As briefly discussed above, embodiments of the present disclosure are directed to an HVAC system having an improved heat pump system. The heat pump system (e.g., reverse-cycle heat pump system, energy efficient heat pump) may include a compressor having an injection port configured to receive a flow of vapor and/or liquid working fluid at an intermediate portion of the compressor, such as between a suction port and a discharge port of the compressor. In other words, the compressor is configured to receive a first flow (e.g., primary flow) of working fluid from a heat exchanger (e.g., directly from the heat exchanger) of the heat pump system, and the compressor is also configured to receive a second flow (e.g., secondary flow) of vapor and/or liquid working fluid via the injection port. A combined flow of the first flow of working fluid and the second flow of working fluid is discharged via the discharge port of the compressor. By injecting working fluid into the injection port of the compressor at an intermediate location of the compressor, an amount of cooling is provided to the compressor, which may enable more efficient operation of the compressor. Additionally, injection of working fluid into the compressor via the injection port may increase a mass flow rate of working fluid discharged by the compressor, which may increase an operating capacity of the particular heat exchanger that receives the discharged working fluid from the compressor in a particular operating mode of the heat pump system. In the manners described below, the present techniques provide energy efficient heat pumps configured to operate and satisfy heating demands, such as in cold climate conditions, with improved efficiency, reduced energy consumption, and without operation of a furnace or other heating system configured to combust or consume a fuel, thereby enabling a reduction of greenhouse gas emissions.

To provide context for the following discussion,FIG.5is a schematic of an embodiment of a portion of an HVAC system100that includes a heat pump102(e.g., a heat pump system, a reverse-cycle heat pump, an energy efficient heat pump) in accordance with present embodiments. The heat pump102may include one or more components of the vapor compression system72discussed above and/or may be included in any of the systems described above (e.g., the HVAC unit12, the heating and cooling system50). The heat pump102includes a first heat exchanger104and a second heat exchanger106that are fluidly coupled to one another via a working fluid circuit108or working fluid loop (e.g., one or more conduits, refrigerant circuit). The first heat exchanger104may be in thermal communication with (e.g., fluidly coupled to) a thermal load110(e.g., a room, space, and/or device) serviced by the heat pump102, and the second heat exchanger106may be in thermal communication with an ambient environment112(e.g., the atmosphere, outdoor environment) surrounding the HVAC system100.

In some embodiments, a first fan116(e.g., blower) may direct a first air flow across the first heat exchanger104to facilitate heat exchange between working fluid within the first heat exchanger104and the thermal load110, while a second fan118may direct a second air flow across the second heat exchanger106to facilitate heat exchange between working fluid within the second heat exchanger106and the ambient environment112. Thus, the heat pump102may be an air-source heat pump. One or more expansion devices120(e.g., an electronic expansion valve [EEV], a bi-directional expansion valve) may be disposed along the working fluid circuit108between the first heat exchanger104and the second heat exchanger106and may be configured to regulate (e.g., throttle) a flow of working fluid and/or a working fluid pressure differential between the first and second heat exchangers104,106.

The heat pump102also includes a compressor130(e.g., compressor system, positive displacement compressor) disposed along the working fluid circuit108. The compressor130is configured to direct working fluid flow through the first heat exchanger104, the second heat exchanger106, and remaining components (e.g., the expansion device(s)120) that may be fluidly coupled to the working fluid circuit108. Although one compressor130is shown in the illustrated embodiment, the heat pump102may include any suitable quantity of compressors130, such as two, three, four, five, six, or more than six compressors130. The compressor130may be a fixed speed compressor, a multi-stage (e.g., two stage) compressor, and/or a variable speed compressor. Additionally, the compressor130may be a rotary compressor, a scroll compressor, a screw compressor, or any other suitable type of compressor (e.g., high-side shell compressor, positive displacement compressor).

The compressor130is configured to receive working fluid (e.g., a primary flow of working fluid) via a suction conduit132fluidly coupled to a suction port134of the compressor130and to discharge working fluid (e.g., compressed working fluid) via a discharge conduit136fluidly coupled to a discharge port138of the compressor130. Further, the compressor130is also configured to receive an injected flow of working fluid (e.g., a secondary flow of working fluid) via one or more injection ports140of the compressor130, as described in further detail below. As shown, the one or more injection ports140may be configured to direct the injected flow of working fluid into the compressor130at an intermediate location between the suction port134and the discharge port138of the compressor130. That is, the one or more injection ports140are configured to direct the injected flow of working fluid into the compressor130downstream of the suction port134and upstream of the discharge port138, relative to a flow direction of working fluid through the compressor130. In some embodiments, the compressor130may include multiple injection ports140positioned at different intermediate locations along the compressor130(e.g., along a working fluid flow path of the compressor130from the suction port134to the discharge port138).

The compressor130may be fluidly coupled to a remainder of the working fluid circuit108via a reversing valve150(e.g., a switch-over valve). In the illustrated embodiment, the reversing valve150includes a first port152that is fluidly coupled to the suction conduit132, a second port154that is fluidly coupled to the discharge conduit136, a third port156that is fluidly coupled to a first conduit portion158of the working fluid circuit108extending to the first heat exchanger104, and a fourth port160that is fluidly coupled to a second conduit portion162of the working fluid circuit108extending to the second heat exchanger106.

The reversing valve150is configured to transition between a first configuration164, in which the reversing valve150fluidly couples the first port152and the fourth port160and fluidly couples the second port154and the third port156, and a second configuration170(FIG.6), in which the reversing valve150fluidly couples the first port152and the third port156and fluidly couples the second port154and the fourth port160. Accordingly, in the first configuration164, the reversing valve150enables the compressor130to receive a flow of working fluid (e.g., via the suction port134) from the second heat exchanger106and to discharge a flow of working fluid (e.g., via the discharge port138) to the first heat exchanger104. Conversely, in the second configuration170, the reversing valve150enables the compressor130to receive a flow of working fluid (e.g., via the suction port134) from the first heat exchanger104and to discharge a flow of working fluid (e.g., via the discharge port138) to the second heat exchanger106. In this way, while in the first configuration164, the reversing valve150enables the heat pump102to operate in a heating mode, in which the first heat exchanger104rejects thermal energy to the thermal load110to heat the thermal load and the second heat exchanger106absorbs thermal energy from the ambient environment112. Further, while in the second configuration170, the reversing valve150enables the heat pump102to operate in a cooling mode, in which the first heat exchanger104absorbs thermal energy from the thermal load110to cool the thermal load and the second heat exchanger106rejects the absorbed thermal energy (e.g., absorbed from the thermal load110) to the ambient environment112. As such, while the reversing valve150is in the first configuration164, the compressor130may direct a working fluid flow along at least a portion of the working fluid circuit108in a first flow direction172. While the reversing valve150is in the second configuration170, the compressor130may direct a working fluid flow along at least a portion of the working fluid circuit108in a second flow direction174, opposite the first flow direction172. For clarity, the heat pump102(e.g., energy efficient heat pump) is shown configured for operation in a heating mode in the illustrated embodiment ofFIG.5. Moreover,FIG.6is a schematic of an embodiment of a portion of the HVAC system100illustrating the heat pump102(e.g., energy efficient heat pump) configured for operation in a cooling mode.

The present discussion continues with reference toFIG.5. The heat pump102may also include additional components, such as an accumulator180and/or a compensator182. The accumulator180is generally configured to enable control of an amount of liquid working fluid circulating in the working fluid circuit108. For example, the accumulator180may enable adjustment in the amount of liquid working fluid circulating in the working fluid circuit108in low ambient conditions (e.g., cold temperatures in the ambient environment112). The compensator182may also be configured to enable control of an amount of working fluid circulating in the working fluid circuit108. For example, the compensator182may be configured to retain a portion of working fluid therein during the heating mode of the heat pump102, such that the portion of retained working fluid does not circulate through the working fluid circuit108(e.g., in the first flow direction172), to improve operation of the heat pump102in the heating mode.

As mentioned above, the heat pump102is also configured to enable injection of working fluid into the compressor130. Specifically, present embodiments include the heat pump102configured to divert a portion of working fluid within the working fluid circuit108and to inject the portion of working fluid into the compressor130via the injection port140of the compressor130. To this end, the heat pump102(e.g., the working fluid circuit108) includes an injection conduit200extending from a liquid conduit portion202(e.g., a third conduit portion) of the working fluid circuit108to the injection port140of the compressor130. As shown, the liquid conduit portion202extends between the first heat exchanger104and the second heat exchanger106. Thus, working fluid directed through the liquid conduit portion202may be in a liquid phase in both the heating mode and cooling mode of the heat pump102. For example, in the heating mode, the working fluid may flow along the working fluid circuit108through (e.g., sequentially through) the first conduit portion158, the first heat exchanger104, the liquid conduit portion202, the second heat exchanger106, and the second conduit portion162.

In the heating mode, liquid working fluid may be directed along the liquid conduit portion202(e.g., in the first flow direction172) from the first heat exchanger104toward the second heat exchanger106. As indicated by arrow204, a portion the working fluid within the liquid conduit portion202may be diverted to the injection conduit200for injection into the compressor130via the injection port140. The working fluid may be provided to the injection port140as a vapor working fluid or as a liquid-vapor mixture of working fluid. To this end, the heat pump102includes an expansion device206disposed along the injection conduit200. For example, the expansion device206may be an electronic expansion valve (EEV), a modulating valve, a solenoid valve, a fixed orifice, a capillary tube, or a combination thereof. Thus, the expansion device206may operate to reduce a pressure and/or a temperature of (e.g., “flash”) the portion of the working fluid directed from the liquid conduit portion202to the injection conduit200, which may cause the working fluid within the injection conduit200to vaporize or partially vaporize. The expansion device206may also be controlled to enable adjustment of the flow of working fluid directed along the injection conduit200to the injection port140of the compressor130, as discussed further below.

The HVAC system100may also include a controller220(e.g., a control system, a thermostat, a control panel, control circuitry, automation controller) that is communicatively coupled to one or more components of the heat pump102and is configured to monitor, adjust, and/or otherwise control operation of one or more components of the heat pump102. For example, one or more control transfer devices, such as wires, cables, wireless communication devices, and the like, may communicatively couple the compressor130, the expansion device(s)120, the first and/or second fans116,118, the control device16(e.g., a thermostat), and/or any other suitable components of the HVAC system100to the controller220. That is, the compressor130, the expansion device(s)120, the first and/or second fans116,118, and/or the control device16may each have one or more communication components that facilitate wired or wireless (e.g., via a network) communication with the controller220. In some embodiments, the communication components may include a network interface that enables the components of the HVAC system100to communicate via various protocols such as EtherNet/IP, ControlNet, DeviceNet, or any other communication network protocol. Alternatively, the communication components may enable the components of the HVAC system100to communicate via mobile telecommunications technology, Bluetooth®, near-field communications technology, and the like. As such, the controller220, the compressor130, the expansion device(s)120, the first and/or second fans116,118, and/or the control device16may wirelessly communicate data between each other. In other embodiments, operational control of certain components of the heat pump102may be regulated by one or more relays or switches (e.g., a 24 volt alternating current [VAC] relay).

In some embodiments, the controller220may be a component of or may include the control panel82. In other embodiments, the controller220may be a standalone controller, a dedicated controller, or another suitable controller included in the HVAC system100. In any case, the controller220is configured to control components of the HVAC system100in accordance with the techniques discussed herein. The controller220includes processing circuitry222, such as a microprocessor, which may execute software for controlling the components of the HVAC system100. The processing circuitry222may include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICS), or some combination thereof. For example, the processing circuitry222may include one or more reduced instruction set (RISC) processors.

The controller220may also include a memory device224(e.g., a memory) that may store information, such as instructions, control software, look up tables, configuration data, etc. The memory device224may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as read-only memory (ROM). The memory device224may store a variety of information and may be used for various purposes. For example, the memory device224may store processor-executable instructions including firmware or software for the processing circuitry222execute, such as instructions for controlling components of the HVAC system100(e.g., the heat pump102). In some embodiments, the memory device224is a tangible, non-transitory, machine-readable-medium that may store machine-readable instructions for the processing circuitry222to execute. The memory device224may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The memory device224may store data, instructions, and any other suitable data.

In accordance with present techniques, the controller220may also be configured to control operation of the expansion device206disposed along the injection conduit200. In particular, the controller220may regulate operation of the expansion device206to control flow of the working fluid through the injection conduit200to the injection port140. Indeed, the expansion device206may be controlled to adjust one or more properties of the working fluid injected into the compressor130(e.g., via the injection port140), such as a flow rate, a temperature, a pressure, a phase, or other attribute of the working fluid. The controller220may also regulate operation of the expansion device206to achieve other operating parameters (e.g., target operating parameters) of the heat pump102. For example, the heat pump102may include one or more sensors226configured to detect one or more operating parameters of the heat pump102, and the controller220may control operation of the expansion device206(e.g., adjust a position of the expansion device206) based on feedback received from the one or more sensors226. The one or more sensors226may be configured to detect any suitable operating parameter associated with the heat pump102, such as temperature, pressure, flow rate, and so forth.

In some embodiments, one or more of the sensors226may be disposed along the discharge conduit136and may be configured to detect a temperature and/or a pressure (e.g., operating parameter) of working fluid discharged by the compressor130. In such embodiments, the controller220may control operation of the expansion device206to adjust flow of working fluid injected into the compressor130via the injection port140to achieve a desired temperature and/or pressure of the working fluid (e.g., desired superheat, desired discharge temperature, desired operating parameter value) discharged by the compressor130. In some embodiments, the controller220may control operation of the expansion valve206based on other parameters, such as a speed of the compressor130, a stage of the compressor130, an operating mode of the heat pump102, a set point temperature of a space conditioned by the heat pump102, a detected temperature of the space conditioned by the heat pump102, a temperature of the ambient environment112, and so forth. For example, the controller220may be configured to operate the expansion device206to enable injection of working fluid into the compressor130via the injection port140during operation of the compressor130at an upper speed limit (e.g., highest speed, full capacity).

The working fluid within the injection conduit200may be injected into the compressor130via the injection port140to enable improved operation of the heat pump102. For example, present embodiments may enable improved operation of the heat pump102in cold climate conditions (e.g., cold temperatures of the ambient environment112) that may also coincide with increased demands for heating by the heat pump102(e.g., increase demand of the thermal load110). As will be appreciated, in cold climate conditions, a discharge temperature and/or discharge superheat of the working fluid discharged by the compressor130may be greater than desired (e.g., in the heating mode of the heat pump102) Accordingly, the heat pump102may operate to direct vapor working fluid and/or a vapor-liquid mixture of working fluid into the compressor130via the injection conduit200and injection port140, which may cause cooling of working fluid within the compressor130and reduce the discharge temperature and/or superheat of the working fluid discharged by the compressor130. The injected working fluid may also cause cooling of the compressor130. In this way, the present techniques may enable improved operation of the heat pump102in cold climate conditions. For example, present embodiments enable improved operation of the heat pump102during periods of compressor130operation at greater pressure ratios.

In some embodiments, the disclosed techniques may enable an increase in operating efficiency of the compressor130and the heat pump102. As will be appreciated, operation of the compressor130with greater efficiency may enable operation of the heat pump102with reduced energy consumption. Indeed, as discussed above, the controller220may adjust operation of the expansion device206based on feedback from one or more of the sensors226, whereby the feedback is indicative of the superheat or discharge temperature of the discharged working fluid. In some embodiments, the one or more sensors226may include a pressure transducer and a temperature sensor disposed along the discharge conduit136, feedback from the pressure transducer and the temperature sensor may be received by the controller220, and the controller220may determine a discharge temperature and/or superheat of the working fluid discharged by the compressor130.

The controller220may control the expansion device206such that the discharged working fluid achieves a particular discharge superheat or temperature (e.g., set point, set point value) and/or does not exceed a particular discharge superheat or discharge temperature (e.g., set point, set point value). A set point of the desired discharge superheat or discharge temperature may be based on a particular embodiment of the heat pump102, a particular embodiment or type of the compressor130, or other suitable parameter. In some embodiments, the set point of the desired discharge superheat or discharge temperature may be stored in the memory device224. The controller220may be configured to receive feedback from one of the sensors226indicative of the discharge superheat or discharge temperature of the working fluid, compare the feedback to the set point (e.g., set point value) stored in the memory device224, and adjust operation of the expansion device206to cause the measured discharge superheat or discharge temperature to approach the set point discharge superheat or discharge temperature.

Additionally or alternatively, the injection conduit200and expansion device206may be utilized and/or controlled to increase an operating capacity of the compressor130, the first heat exchanger104, the second heat exchanger106, and/or the heat pump102generally. As mentioned above, the working fluid injected into the compressor130via the injection port140(e.g., secondary flow of working fluid) is combined with a primary flow of working fluid received via the suction port134in the compressor130. Thus, a mass flow rate of working fluid discharged by the compressor130may be greater that a mass flow rate of working fluid received by the compressor130via the suction port134. In some instances, the increase in mass flow rate of working fluid discharged by the compressor130may enable an increase in a heating capacity of the heat pump102(e.g., the first heat exchanger104) in the heating mode of the heat pump102. As will be appreciated, the increased heating capacity of the heat pump102(e.g., the first heat exchanger104) in the heating mode may enable the heat pump102to satisfy greater heating loads in cold climates without utilization of an auxiliary heating system, such as a furnace that combusts a fuel to provide supplemental. In this way, present embodiments enable a reduction in the generation of greenhouse gas emissions.

It should be appreciated that techniques similar to those described above may be utilized during operation of the heat pump102in the cooling mode of the heat pump102. In some instances, it may be desirable (e.g., based on feedback from the one or more sensors226) to block flow of working fluid along the injection conduit200and therefore block injection of working fluid into the compressor130via the injection port140. For example, at certain temperatures of the ambient environment112, it may be desirable to block injection of working fluid into the compressor130via the injection port140. In such instances, for example, the controller220may adjust the expansion device206to a closed position. In other embodiments, the expansion device206may include a fixed orifice or capillary tube and a solenoid valve, and the solenoid valve may be adjusted to a closed position to block working fluid flow to the injection port140. At other temperatures of the ambient environment112(e.g., higher temperatures), it may be desirable to enable injection of working fluid into the compressor130via the injection port140.

In some embodiments, one of the sensors226may be configured to detect a temperature of the ambient environment112and provide feedback indicative of the temperature to the controller220. The controller220may compare the feedback indicative of the temperature to a set point temperature (e.g., stored in the memory device224) and adjust a position of the expansion device206based on the comparison. For example, the set point temperature may be approximately 90 degrees Fahrenheit. In response to a determination that the temperature of the ambient environment112is at or above the set point temperature, the controller220may adjust the expansion device206toward an open position to enable injection of working fluid into the compressor130via the injection port140. In response to a determination that the temperature of the ambient environment112is below the set point temperature, the controller220may adjust the expansion device206toward a closed position to block injection of working fluid into the compressor130via the injection port140. Additionally or alternatively, in the cooling mode, the controller220may control and/or adjust a position of the expansion device206(e.g., based on feedback from one or more of the sensors226) to achieve a desired discharge superheat and/or discharge temperature, in the manner similarly described above.

As discussed above, present embodiments also enable more efficient operation of the heat pump102with reduced energy consumption and reduced emissions at significantly reduced costs. For example, the present techniques enable more efficient operation of the heat pump102in cold climate conditions, during operation of the compressor130at higher pressure ratios, and so forth, at reduced costs compared to traditional systems. Indeed, it will be appreciated that the injection conduit200and the expansion device206may be implemented at a reduced cost compared to traditional systems incorporating more expensive and more complicated components.

As set forth above, embodiments of the present disclosure may provide one or more technical effects useful for enabling operation of a heat pump system in both a cooling mode and a heating mode in cold climate conditions. Indeed, implementation of the disclosed heat pump system (e.g., energy efficient heat pump) with the injection conduit and expansion device may enable operation of a compressor at higher pressure ratios, improve an overall operational efficiency of an HVAC system during cooling and heating operations, improve an operating capacity of the HVAC system, as well as reduce costs and complexity associated with manufacture, operation, and/or maintenance of the HVAC system. As a result, the present techniques enable utilization of heat pumps (e.g., without auxiliary heating systems, such as furnaces) to satisfy greater demands (e.g., heating demands) with reduced energy consumption and reduced greenhouse gas emissions. It should be understood that the technical effects and technical problems in the specification are examples and are not limiting. Indeed, it should be noted that the embodiments described in the specification may have other technical effects and can solve other technical problems.

While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, such as temperatures and pressures, mounting arrangements, use of materials, colors, orientations, and so forth, 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 disclosure.

Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode, or those unrelated to enablement. 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.

The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).