Systems for controlling operation of a hvac&r system

Abstract

A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a working fluid circuit configured to circulate a working fluid therethrough and a compressor disposed along the working fluid circuit and configured to pressurize the working fluid. The compressor includes a housing having an impeller cavity configured to direct the working fluid therethrough and a first flow path fluidly coupled to the impeller cavity and to an ambient environment surrounding the compressor. The HVAC&R system also includes a control system configured to operate the compressor in a standby mode, where a demand for conditioning by the HVAC&R system is absent in the standby mode and, in the standby mode, operate the HVAC&R system to increase a pressure of the working fluid to meet or exceed a threshold pressure value.

Description

[0001] SYSTEMS FOR CONTROLLING OPERATION OF A HVAC&R SYSTEM

[0002] Description

[0003] CROSS-REFERENCE TO RELATED APPLICATION

[0004] This application claims priority from and the benefit of U.S. Provisional Patent Application No. 63 / 531,513, entitled "SYSTEMS AND METHODS FOR CONTROLLING OPERATION OF AN HVAC&R SYSTEM," filed August 8, 2023, which is hereby incorporated by reference in its entirety for all purposes.

[0005] BACKGROUND

[0006] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0007] Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems, or vapor compression systems (e.g., heat pump systems), utilize a working fluid (e.g., a refrigerant) that changes phases between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures within components of the HVAC&R system. The HVAC&R system may place the working fluid in a heat exchange relationship with a conditioning fluid (e.g., water) and may deliver the conditioning fluid to conditioning equipment and / or a conditioned environment serviced by the HVAC&R system. Furthermore, the conditioning fluid may be directed through downstream equipment, such as air handlers, to condition other fluids, such as air in a building. In general, an HVAC&R system or vapor compression system may include a compressor configured to circulate the working fluid through the system. Operation of the compressor may be driven by a motor. In many applications, the motor of the compressor is cooled by a cooling system. For example, a cooling fluid may be directed through the motor to enable rejection of heat generated by the motor during operation of the compressor. Unfortunately, existing cooling systems for compressor motors may be susceptible to various inefficiencies, which may cause inefficient operation of the HVAC&R system.

[0008] SUMMARY

[0009] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0010] In one embodiment, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a working fluid circuit configured to circulate a working fluid therethrough and a compressor disposed along the working fluid circuit and configured to pressurize the working fluid. The compressor includes a housing having an impeller cavity configured to direct the working fluid therethrough and a first flow path fluidly coupled to the impeller cavity and to an ambient environment surrounding the compressor. The HVAC&R system also includes a control system configured to operate the compressor in a standby mode, where a demand for conditioning by the HVAC&R system is absent in the standby mode and, in the standby mode, operate the HVAC&R system to increase a pressure of the working fluid to meet or exceed a threshold pressure value.

[0011] In another embodiment, heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a compressor having an impeller cavity and an impeller disposed within the impeller cavity, where the compressor is configured to pressurize a working fluid within the impeller cavity, and a motor coupled to the compressor, where the motor is configured to drive rotation of the impeller to pressurize the working fluid, and the motor includes a motor cavity configured to circulate a cooling fluid therethrough. The HVAC&R system also includes a first flow path extending between the impeller cavity and an ambient environment surrounding the HVAC&R system and a second flow path extending between the motor cavity and the ambient environment surrounding the HVAC&R system. The HVAC&R system further includes a control system configured to operate the HVAC&R system in a normal operating mode in response to a demand for heating or cooling and operate the HVAC&R system in a standby mode in an absence of the demand for heating or cooling, where the control system is configured to operate the HVAC&R system to increase a pressure of the working fluid in the standby mode.

[0012] In a further embodiment, a control system of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system is configured to determine that a heating or cooling demand of the HVAC&R system is absent, operate the HVAC&R system in a standby mode based on the determination that the heating or cooling demand of the HVAC&R system is absent, receive data indicative of a detected parameter value of a working fluid of the HVAC&R system in the standby mode, determine that the detected parameter value is below a threshold value in the standby mode, where the threshold value is based on a pressure of an ambient environment surrounding the HVAC&R system, and operate the HVAC&R system in the standby mode to increase the detected parameter value of the working fluid in response to the determination that the detected parameter value is below the threshold value.

[0013] BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

[0015] FIG. 1 is a perspective view of an embodiment of a building that may utilize a heating, ventilating, air conditioning, and / or refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure;

[0016] FIG. 2 is a perspective view of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0017] FIG. 3 is a schematic of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure; FIG. 4 is a schematic of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0018] FIG. 5 is a cross-sectional side view of a portion of an embodiment of a compressor of an HVAC&R system, in accordance with an aspect of the present disclosure;

[0019] FIG. 6 is a cross-sectional side view of an embodiment of a sealing system of a compressor of an HVAC&R system, in accordance with an aspect of the present disclosure;

[0020] FIG. 7 is a schematic of an embodiment of an HVAC&R system including a heat pump system and a heating system, in accordance with an aspect of the present disclosure; and

[0021] FIG. 8 is a flow diagram of an embodiment of a method of a standby operation for an HVAC&R system, in accordance with an aspect of the present disclosure.

[0022] DETAILED DESCRIPTION

[0023] 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 may 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.

[0024] 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.

[0025] As briefly discussed above, a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system may be used to thermally regulate a space within a building, home, or other suitable structure. For example, the HVAC&R system may include a vapor compression system (e.g., chiller system, vapor compression circuit, heat pump system) that transfers thermal energy between a working fluid (e.g., refrigerant, heat transfer fluid, water) and a fluid to be conditioned (e.g., air, water, brine). The vapor compression system may include a condenser (e.g., first heat exchanger) and an evaporator (e.g., second heat exchanger) that are fluidly coupled to one another via one or more conduits (e.g., vapor compression circuit, working fluid circuit, refrigerant circuit). A compressor may be included in the vapor compression system to pressurize and circulate the working fluid through the one or more conduits of the vapor compression system and, thus, enable the transfer of thermal energy between the working fluid and the fluid to be conditioned, such as via the condenser and / or the evaporator.

[0026] Compressors (e.g., centrifugal compressors, direct drive compressors, open compressors, open design compressors, non-hermetic compressors) may be designed for certain operating conditions, which may depend on one or more characteristics or parameters of the working fluid (e.g., refrigerant, water). For example, operation (e.g., operating parameters, operating speeds, rotational speeds, target speeds, threshold speeds) of the compressors may be determined, utilized, and / or selected based on such characteristics or parameters of the working fluid (e.g., refrigerant, water). Compressors may be designed and / or selected for implementation in the HVAC&R system based on working fluid flow rates, working fluid temperatures and / or pressures, cooling and / or heating loads of the HVAC&R system, conditions during operation of the compressor, such as conditions at a suction inlet of the compressor and / or at a discharge outlet of the compressor, or any combination thereof. In some applications, the HVAC&R system may be configured to utilize water as the working fluid. In particular, the HVAC&R system may include a compressor configured to circulate the water through a working fluid circuit and components of the HVAC&R system. As mentioned above, operation of the compressor may be driven by a motor of the compressor. The compressor and / or the HVAC&R system may include a cooling system designed to enable rejection of heat generated by the motor during operation of the compressor. In some applications, a cooling fluid, such as water, air, or other fluid, may be circulated through a housing of the motor to provide cooling. The cooling fluid may absorb heat generated by the motor to remove the heat from the motor. For example, air may be circulated and / or ventilated through the motor (e.g., motor cavity) of the compressor and may be discharged to an environment surrounding the compressor.

[0027] In accordance with present techniques, the compressor may include a sealing system (e.g., labyrinth seal system, venting system) configured to enable separation of a working fluid circulated through the vapor compression system by the compressor and a cooling fluid circulated through the motor of the compressor. In some embodiments, the sealing system may also enable venting (e.g., discharge) of the working fluid (e.g., water, steam) from the compressor, as well as venting (e.g., discharge) of the cooling fluid from the motor of the compressor. For example, the sealing system may enable simultaneous venting of working fluid from an impeller cavity (e.g., working fluid portion) of the compressor and venting of cooling fluid from a motor cavity (e.g., cooling fluid portion) of the motor.

[0028] As will be appreciated, operation of the compressor may be adjusted, such as based on various heating and / or cooling demands of the HVAC&R system. For example, an operating capacity of the HVAC&R system may be reduced and an operating speed of the compressor may therefore be reduced. In some instances, operation of the compressor may be suspended, such as instances in which a heating demand and / or a cooling demand of the HVAC&R system is satisfied and / or nonexistent (e.g., absent). As described herein, an operational stage or mode of the HVAC&R system in which the HVAC&R system (e.g., compressor) does not operate to satisfy a load (e.g., heating demand, cooling demand) of the HVAC&R system may be referred to as a standby mode. In such operational stages, when operation of the compressor is reduced or suspended, a saturation temperature of the working fluid within the compressor (e.g., impeller cavity, working fluid portion) may decrease. For example, in HVAC&R systems utilizing water as the working fluid, a saturation temperature of the water may decrease (e.g., below 100°C) due to thermal losses, for example. As a result, a pressure within the compressor (e.g., impeller cavity, a pressure of the working fluid) may decrease (e.g., below 1 bar, below 1.1 bar). As the pressure of the working fluid within the impeller cavity of the compressor and / or within the vapor compression system decreases, cooling fluid within the motor (e.g., motor cavity, motor housing) of the compressor may migrate toward the impeller cavity (e.g., across the sealing system). For example, a pressure differential between the impeller cavity and the motor cavity may cause the cooling fluid (e.g., air, noncondensable air) within the motor cavity to flow from the motor cavity and towards the impeller cavity of the compressor. In some instances, the pressure of the working fluid within the impeller cavity may additionally or alternatively be less than a pressure of an environment surrounding the compressor (e.g., atmospheric pressure), which may similarly induce migration of atmospheric or ambient air (e.g., non-condensable air) into the impeller cavity of the compressor. Introduction of the cooling fluid and / or ambient air into the impeller cavity of the compressor may cause inefficiencies in the HVAC&R system. For example, non-condensable air introduced into the impeller cavity, such as during reduced, suspended, or non-operation of the compressor, should be purged before operation of the compressor is resumed and / or increased. Purging of non- condensable air within the impeller cavity of the compressor may delay a start-up process of the compressor. Therefore, improved HVAC&R systems that enable more efficient operational control (e.g., reduced or suspended operational control, standby mode control, start-up process control) of the compressor, such as during and / or after reducing and / or suspending operation of the compressor, are desired.

[0029] Accordingly, present embodiments are directed to an HVAC&R system configured to reduce, mitigate, and / or block migration of cooling fluid and / or ambient air (e.g., air, non-condensable air, motor cooling fluid) from a motor of a compressor (e.g., motor cavity, cooling fluid portion) into a working fluid portion (e.g., impeller cavity) of the compressor. In accordance with present techniques, the HVAC&R system is also configured to reduce, mitigate, and / or block migration of working fluid from the working fluid portion of the compressor into the motor of the compressor. For example, present embodiments include systems and methods for operating an HVAC&R system and / or a compressor of the HVAC&R system to block undesirable migration of working fluid, cooling fluid, ambient air, or any combination thereof within the compressor and / or across components of the compressor. In some embodiments, the HVAC&R system (e.g., compressor) is configured to operate in a standby mode to enable heating of the working fluid within the compressor. The HVAC&R system may operate in the standby mode during instances in which the HVAC&R system does not operate to satisfy a load or demand on the HVAC&R system. In some implementations, operation in the standby mode may include operation of the compressor at a relatively low speed to increase and / or maintain a pressure of the working fluid within the compressor (e.g., impeller cavity). In some implementations, the compressor may be a multistage compressor that includes multiple stages (e.g., compressor stages, stages arranged in series), and thus operation in the standby mode may include operating and / or maintaining operation of a reduced number of compressor stages to increase and / or maintain a pressure of the working fluid within the compressor. As such, operating the compressor in the standby mode may include a fewer number of operating compressor stages (e.g., one, two), such as operating a single compressor stage, as compared to a number of operating compressor stages (e.g., two, three, four) operating during normal operation of the compressor (e.g., to satisfy a load on the HVAC&R system). In additional or alternative embodiments, the HVAC&R system may include a heating system configured to heat the working fluid during non-operation of the compressor and / or during a standby mode of the compressor. In this way, a pressure of the working fluid may be maintained at a level that is equal to or greater than a pressure (e.g., atmospheric pressure) of the cooling fluid within the motor of the compressor and / or an ambient air pressure, which may enable blockage of fluid migration (e.g., air, ambient air, cooling fluid, motor cooling fluid, noncondensable air) into the compressor (e.g., impeller cavity). Thus, frequency of purging operations to remove such fluid from the impeller cavity of the compressor, such as prior to start-up of the compressor to satisfy a demand of the HVAC&R system, may be reduced, which may enable more efficient operation of the HVAC&R system.

[0030] Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system 10 in a building 12 for a typical commercial setting. The HVAC&R system 10 may include a vapor compression system 14 (e.g., a heat pump system) that supplies a chilled liquid, which may be used to cool the building 12. The HVAC&R system 10 may also include a boiler 16 to supply warm liquid to heat the building 12 and an air distribution system which circulates air through the building 12. The air distribution system can also include an air return duct 18, an air supply duct 20, and / or an air handler 22. In some embodiments, the air handler 22 may include a heat exchanger that is connected to the boiler 16 and the vapor compression system 14 by conduits 24. The heat exchanger in the air handler 22 may receive either heated liquid from the boiler 16 or chilled liquid from the vapor compression system 14, depending on the mode of operation of the HVAC&R system 10. The HVAC&R system 10 is shown with a separate air handler on each floor of building 12, but in other embodiments, the HVAC&R system 10 may include air handlers 22 and / or other components that may be shared between or among floors.

[0031] FIGS. 2 and 3 illustrate embodiments of the vapor compression system 14 that can be used in the HVAC&R system 10. The vapor compression system 14 may circulate a working fluid through a working fluid circuit starting with a compressor 32 (e.g., centrifugal compressor, single stage compressor, multi-stage compressor, direct drive compressor, open compressor, non-hermetic compressor). The working fluid circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and a liquid chiller or an evaporator 38. The vapor compression system 14 may further include a control panel 40 that has an analog to digital (A / D) converter 42, a microprocessor 44, a non-volatile memory 46, and / or an interface board 48.

[0032] Some examples of fluids that may be used as working fluids in the vapor compression system 14 are hydrofluorocarbon (HFC) based working fluids (e.g., refrigerants), for example, R-410A, R-407, R-134a, hydrofluoro olefin (HFO), "natural" working fluids like ammonia (NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbon based working fluids, water (e.g., water vapor, steam), or any other suitable working fluid. In some embodiments, the vapor compression system 14 may be configured to efficiently utilize working fluids having a normal boiling point of about 100 degrees Celsius (66 degrees Fahrenheit) at one atmosphere of pressure, also referred to as low pressure working fluids, versus a medium pressure working fluid, such as R-134a. As used herein, "normal boiling point" may refer to a boiling point temperature measured at one atmosphere of pressure.

[0033] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSDs) 52, a motor 50, the compressor 32, the condenser 34, the expansion valve or device 36, and / or the evaporator 38. The motor 50 may drive the compressor 32 and may be powered by a variable speed drive (VSD) 52. The VSD 52 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 may be powered directly from an AC or direct current (DC) power source. The motor 50 may include any type of motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, a direct drive motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

[0034] The compressor 32 compresses or pressurizes a working fluid vapor and delivers the vapor to the condenser 34 through a discharge passage. In some embodiments, the compressor 32 may be a centrifugal compressor. Additionally or alternatively, the compressor 32 may be a direct drive compressor. In some embodiments, the compressor 32 may be a direct drive compressor with an open or non-hermetic design, such that one or more internal components or cavities of the compressor 32 may be exposed to an environment external to the compressor 32. The working fluid vapor delivered by the compressor 32 to the condenser 34 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34. The working fluid vapor may condense to a working fluid liquid in the condenser 34 as a result of thermal heat transfer with the cooling fluid. The liquid working fluid from the condenser 34 may flow through the expansion device 36 to the evaporator 38. In the illustrated embodiment of FIG. 3, the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies the cooling fluid to the condenser 34.

[0035] The liquid working fluid delivered to the evaporator 38 may absorb heat from a conditioning fluid, which may or may not be the same cooling fluid used in the condenser 34. The liquid working fluid in the evaporator 38 may undergo a phase change from the liquid working fluid to a working fluid vapor. As shown in the illustrated embodiment of FIG. 3, the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to a cooling load 62. The cooling fluid of the evaporator 38 (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 38 via return line 60R and exits the evaporator 38 via supply line 60S. The evaporator 38 may reduce the temperature of the conditioning fluid in the tube bundle 58 via thermal heat transfer with the working fluid. The tube bundle 58 in the evaporator 38 can include a plurality of tubes and / or a plurality of tube bundles. In any case, the vapor working fluid exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.

[0036] FIG. 4 is a schematic of an embodiment of the vapor compression system 14 with an intermediate circuit 64 incorporated between condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly coupled to the condenser 34. As shown in the illustrated embodiment of FIG. 4, the inlet line 68 includes a first expansion device 66 positioned upstream of an intermediate vessel 70. In some embodiments, the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler, an economizer, etc.). In other embodiments, the intermediate vessel 70 may be configured as a heat exchanger or a "surface economizer." In the illustrated embodiment of FIG. 4, the intermediate vessel 70 is used as a flash tank, and the first expansion device 66 is configured to lower the pressure of (e.g., expand) the liquid working fluid received from the condenser 34. During the expansion process, a portion of the liquid may vaporize, and thus, the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66.

[0037] Additionally, the intermediate vessel 70 may provide for further expansion of the liquid working fluid due to a pressure drop experienced by the liquid working fluid when entering the intermediate vessel 70 (e.g., due to a rapid increase in volume experienced when entering the intermediate vessel 70). The vapor in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32. In other embodiments, the vapor in the intermediate vessel 70 may be drawn to an intermediate stage of the compressor 32 (e.g., not the suction stage). The liquid that collects in the intermediate vessel 70 may be at a lower enthalpy than the liquid working fluid exiting the condenser 34 because of the expansion in the expansion device 66 and / or the intermediate vessel 70. The liquid from intermediate vessel 70 may then flow in line 72 through a second expansion device 36 to the evaporator 38.

[0038] It should be appreciated that any of the HVAC&R systems discussed above may be utilized in accordance with the present techniques. For example, the present techniques may be incorporated with embodiments of the HVAC&R system 10, the vapor compression system 14, the boiler 16, a chiller, a heat pump, and / or other HVAC&R equipment discussed herein. As briefly discussed above, present embodiments are directed to embodiments of the HVAC&R system 10, such as embodiments configured to utilize water as the working fluid. In some embodiments, the HVAC&R system 10 may be a heat pump, which may be configured to operate in a heating mode and in a cooling mode. In particular, the discussion below describes the present techniques incorporated with embodiments of a heat pump system including the compressor 32 configured to circulate water as a working fluid through the HVAC&R system 10. Furthermore, the compressor 32 includes an embodiment of the motor 50 configured to circulate a cooling fluid, such as air (e.g., environmental air, pressurized air), therethrough to enable cooling of the motor 50. The motor 50 may be configured to enable venting or ventilation of the cooling fluid to an environment surrounding the compressor 32 (e.g., surrounding the HVAC&R system 10). The compressor 32 may include a sealing system (e.g., labyrinth system, venting system) configured to enable venting of working fluid from a working fluid portion (e.g., impeller cavity) of the compressor 32 and to enable venting of the cooling fluid from a cooling fluid portion of the motor 50 (e.g., motor cavity) of the compressor 32. In some embodiments, the sealing system may enable simultaneous venting of cooling fluid from the motor cavity and venting of working fluid from the impeller cavity of the compressor 32. However, it should be appreciated that the techniques described herein may be incorporated with other embodiments of the compressor 32, the vapor compression system 14, and the HVAC&R system 10.

[0039] With the foregoing in mind, FIG. 5 is a cross-sectional side view of an embodiment of the compressor 32 (e.g., non-hermetic compressor), which may be incorporated with a heat pump system 100 of the HVAC&R system 10, in accordance with an aspect of the present disclosure. As discussed herein, the compressor 32 may be a single or multi-stage centrifugal compressor. Additionally or alternatively, the compressor 32 may be a direct drive compressor. As similarly described above, the compressor 32 may be disposed along a working fluid circuit (e.g., vapor compression system 14) and may be configured to circulate a working fluid through the working fluid circuit. For example, the compressor 32 may be configured to circulate water (e.g., water vapor, steam) as the working fluid. The compressor 32 may be configured to operate at operating speeds (e.g., operating speed range, operating revolutions per minute [RPM], up to 40,000 RPM, greater than 40,000 RPM) that may enable more efficient use of water (e.g., water vapor, steam) as the working fluid within the heat pump system 100. To this end, the compressor 32 may include an embodiment of the motor 50 to drive rotation of the compressor 32 at a desired operating speed.

[0040] In addition, the compressor 32 includes a sealing system 102 (e.g., labyrinth seal system, venting system) including one or more seals 104 (e.g., labyrinth seals). The seals 104 are configured to restrict fluid flow within the compressor 32 in a desired manner. For example, the seals 104 may enable venting of a working fluid from the compressor 32 and / or of a cooling fluid (e.g., motor cooling fluid) from the compressor 32 (e.g., from the motor 50 of the compressor 32). One or more of the seals 104 may also block one or more flows of fluid between operational cavities (e.g., spaces, areas) of the compressor 32, as described further below. Furthermore, the compressor 32 may include a housing 106 (e.g., compressor housing, compressor system housing) and a shaft 108 extending through the housing 106. The shaft 108 may be configured to rotate via actuation by the motor 50. In addition, the motor 50 may be housed within a motor cavity 110 of a motor housing 112 (e.g., casing, a portion of the housing 106) of the compressor 32. The motor housing 112 may be considered a portion of the housing 106 of the compressor 32. In some embodiments, the compressor 32 may include a single compressor stage. In other embodiments, the compressor 32 may include two or more compressor stages. The shaft 108 of the compressor 32 is configured to rotate about an axis 114 (e.g., a rotational axis, central axis) of the compressor 32 to enable flow of a working fluid (e.g., water) through the compressor 32. To facilitate the following discussion, the compressor 32 and its components may be described with reference to a longitudinal axis 116, a vertical axis 118, which is oriented relative to a direction of gravity, and a lateral axis 120 (e.g., a radial axis). However, it should be appreciated that the compressor 32 may be installed and / or operated in any suitable position (e.g., vertical, horizontal, at any suitable operational angle), and thus the axis 114 may extend at any suitable angle with respect to the longitudinal axis 116, the vertical axis 118, the lateral axis 120, or any combination thereof.

[0041] In the illustrated embodiment, the compressor 32 includes an inlet 124 (e.g., suction inlet) configured to receive a flow of working fluid (e.g., water, water vapor) and an impeller 126 positioned within an impeller cavity 128 (e.g., fluidly coupled to the inlet 124) of the housing 106 of the compressor 32. The impeller 126 may be coupled (e.g., attached, fixed) to the shaft 108 via a fastener 130 (e.g., rod, bolt, nut, mechanical fastener). The compressor 32 also includes a diffuser passage 132 and a volute 134 formed within the housing 106. It should be appreciated that, although FIG. 5 illustrates the compressor 32 as including a single stage, in some embodiments, the compressor 32 may be a multistage centrifugal compressor (e.g., two stages, three stages, four stages, etc.). In such embodiments, each of the compressor stages may include a respective inlet, impeller, and diffuser passage.

[0042] During operation of the compressor 32, the shaft 108 may rotate (e.g., via operation of the motor 50) and cause rotation of the impeller 126. Rotation of the impeller 126 may draw the working fluid (e.g., water, water vapor) into the housing 106 via the inlet 124 and toward the impeller 126. In particular, rotation of the impeller 126 may drive the working fluid (e.g., from the evaporator 38 and / or from the intermediate vessel 70 of the vapor compression system 14) to flow along a working fluid flow path 136 through the compressor 32. The impeller 126 may impart mechanical energy onto the working fluid and may direct the working fluid towards the diffuser passage 132. The working fluid may be directed through the diffuser passage 132, to the volute 134 of the compressor 32, and from the volute 134 to another component of the heat pump system 100 having the compressor 32, such as a condenser (e.g., the condenser 34), for heat exchange with a fluid, such as a cooling fluid.

[0043] Components of the heat pump system 100 (e.g., compressor 32) may be controlled via a control system 150 (e.g., controller, automation controller) of the HVAC&R system 10. In some embodiments, the control system 150 may correspond to the control panel 40 described above with reference to FIGS. 3 and 4. For example, the control system 150 may include an interface board 152 (e.g., user interface), processing circuitry 154 (e.g., one or more microprocessors), a memory 156, and / or an analog to digital (A / D) converter 158. For example, the memory 156 may include volatile memory, such as random-access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM), optical drives, hard disc drives, solid-state drives, or any other non-transitory computer- readable medium storing instructions that, when executed, control operation of the compressor 32 and / or the HVAC&R system 10. The processing circuitry 154 may be configured to execute such instructions. In certain embodiments, the processing circuitry 154 may include one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more general purpose processors, or any combination thereof.

[0044] The control system 150 may be configured to control operation (e.g., transmit instructions to control operation) of the HVAC&R system 10 (e.g., one or more components of the heat pump system 100, the compressor 32, the motor 50, etc.) to enable more efficient operation of the HVAC&R system 10 and more efficient operation of the heat pump system 100. As discussed in more detail below, the control system 150 may be configured to operate the HVAC&R system 10 (e.g., heat pump system 100, compressor 32, and / or one or more components of the HVAC&R system 10) in a standby mode that blocks flow of working fluid from the impeller cavity 128 into the motor cavity 110 and / or blocks flow of a cooling fluid (e.g., motor cooling fluid) from the motor cavity 110 into the impeller cavity 128. The control system 150 may operate the HVAC&R system 10 in the standby mode during time periods in which the HVAC&R system 10 is not operated in response to a demand for heating and / or cooling of a load (e.g., nonoperating, reduced, and / or stopped stages of the HVAC&R system 10). In other words, the control system 150 may operate the HVAC&R system in the standby mode during instances in which a call for conditioning is absent. In response to demands for heating and / or cooling by the HVAC&R system 10, the control system 150 may be configured to operate the HVAC&R system 10 (e.g., heat pump system 100, compressor 32, and / or one or more components of the HVAC&R system 10) in a standard operating mode (e.g., normal operating mode) to satisfy heating and / or cooling demands of a load of the HVAC&R system 10 (e.g., to provide heating and / or cooling of the conditioning fluid).

[0045] Continuing with FIG. 5, the control system 150 may be configured to control operation of the heat pump system 100 (e.g., compressor 32) based on feedback received from one or more sensors 160 of the heat pump system 100 and / or of the compressor 32. The sensors 160 may be configured to detect one or more operating conditions (e.g., operating parameters, operating parameter values) of the heat pump system 100 as sensor data and provide the sensor data (e.g., feedback) indicative of the operating conditions to the control system 150. The sensors 160 may be communicatively coupled to the control system 150 and may include any suitable sensor configured to detect an operating parameter of the heat pump system 100 and / or the compressor 32, such as pressure sensors, temperature sensors, position sensors, voltage sensors, current sensors, flow rate sensors, humidity sensors, liquid sensors, speed sensors, and so forth.

[0046] Furthermore, during normal operations (e.g., standard operating mode) of the heat pump system 100 (e.g., operation of the compressor 32 to satisfy a demand for heating and / or cooling of a load), a temperature of the working fluid may be elevated (e.g., at or above a threshold temperature value) and thus a pressure of the working fluid within the impeller cavity 128 may be elevated (e.g., at or above a threshold pressure value). Working fluid within the impeller cavity 128 at a pressure greater than a threshold pressure value (e.g., atmospheric pressure) may block fluid (e.g., motor cooling fluid, ambient air, non-condensable air) migration into the impeller cavity 128 from the motor cavity 110 and / or from an environment surrounding the compressor 32 (e.g., block fluid flow across the sealing system 102). For example, during normal operation of the compressor 32, the temperature of the working fluid (e.g., water, steam), may be at and / or above 100°C, which may cause the pressure of the water within the impeller cavity 128 to be equal to or greater than approximately 1 bar (e.g., 1.1 bar, at and / or above 1 bar). In addition, in some embodiments, air or other cooling fluid within the motor cavity 110 may be maintained at a target pressure (e.g., via pressurized air, an air pump) of approximately 1 bar (e.g., 1.1 bar, at and / or above 1 bar) to enable circulation of the air through the motor cavity 110 and provide cooling to the motor 50. In any case, during normal operation of the compressor 32, a first pressure (e.g., working fluid pressure) within the impeller cavity 128 may be greater than a second pressure (e.g., cooling fluid pressure) within the motor cavity 110, and flow of fluid (e.g., ambient air, motor cooling fluid) across the sealing system 102 and into the impeller cavity 128 may therefore be blocked.

[0047] As discussed in more detail below, the sealing system 102 (e.g., labyrinth seal system, venting system, one or more seals 104) is configured to enable venting of the impeller cavity 128 and / or the motor cavity 110 (e.g., into the environment surrounding the compressor 32). The sealing system 102 may be disposed within the housing 106 of the compressor 32 and may be configured to enable venting of working fluid (e.g., steam) from the impeller cavity 128. The sealing system 102 may also be configured to enable venting of cooling fluid (e.g., air) from the motor cavity 110. The structure (e.g., design, configuration, components, arrangement) of the sealing system 102 may also block flow of cooling fluid (e.g., air) from the motor cavity 110 into the impeller cavity 128. For example, the sealing system 102 may block flow of a cooling fluid from the motor cavity 110 into the impeller cavity 128 during operation (e.g., normal operation, operation to satisfy heating and / or cooling demand of a load) of the compressor 32 (e.g., working fluid pressure above a corresponding threshold value, cooling fluid pressure above a corresponding threshold value). Similarly, the sealing system 102 may block flow of working fluid (e.g., water) from the impeller cavity 128 into the motor cavity 110, such as during operation (e.g., normal operation, operation to satisfy heating and / or cooling demand of a load) of the compressor 32 (e.g., working fluid pressure above a corresponding threshold value, cooling fluid pressure above a corresponding threshold value). In some embodiments, the sealing system 102 may additionally or alternatively be configured to block flow of ambient air from the environment surrounding the compressor 32 into the impeller cavity 128 of the compressor 32 during operation of the compressor 32 (e.g., normal operation, operation to satisfy heating and / or cooling demand of a load).

[0048] In some instances, operation of the compressor 32 may be limited, reduced, or suspended, such as in response to varying heating and / or cooling demands of the heat pump system 100 (e.g., an absence of a heating and / or cooling demand of a load of the heat pump system 100, reduced heating and / or cooling demand, a heating and / or cooling demand is inactive). For example, an operational speed of the compressor 32 (e.g., the impeller 126) may be reduced and / or rotation of the impeller 126 may be suspended. In such instances, the compressor 32 may not operate to pressurize the working fluid, increase a temperature of the working fluid, and / or drive flow of the working fluid through the heat pump system 100. As a result, a temperature (e.g., saturation temperature) of the working fluid (e.g., water, steam) within the impeller cavity 128 of the compressor 32 may decrease (e.g., below 100°C, below a threshold value). Similarly, a pressure of the working fluid within the impeller cavity 128 may decrease (e.g., below 1 bar, below 1.1 bar, below a threshold value). However, in some instances, a pressure of the cooling fluid (e.g., air) within the motor cavity 110 may not decrease and / or may remain at a pressure level above the pressure of the working fluid (e.g., above the threshold value).

[0049] When the pressure of the working fluid within the impeller cavity 128 is below a threshold value (e.g., below a pressure of the cooling fluid within the motor cavity 110, a predetermined threshold value), a pressure differential between the impeller cavity 128 and the motor cavity 110 may develop. Specifically, a pressure within the impeller cavity 128 may fall below a pressure within the motor cavity 110. As a result, migration of the cooling fluid (e.g., air, noncondensable air) within the motor cavity 110 toward the impeller cavity 128 of the compressor 32 may be induced (e.g., due to a pressure gradient and / or pressure differential). In some embodiments, the pressure of the working fluid within the impeller cavity 128 may additionally or alternatively be less than a pressure of an environment surrounding the compressor 32 (e.g., atmospheric pressure), which may similarly induce migration of atmospheric or ambient air (e.g., non-condensable air) into the impeller cavity 128. Introduction of the cooling fluid and / or ambient air into the impeller cavity 128 may cause inefficiencies in the heat pump system 100. Moreover, a presence and / or likelihood of cooling fluid, such as air, and / or ambient air within the impeller cavity 128 may prompt purging operations and / or procedures to remove the non- condensable air and / or cooling fluid within the impeller cavity 128 before the compressor 32 may be operated to satisfy heating and / or cooling demand of a load on the heat pump system 100. In other words, resumed operation of the compressor 32 may be delayed while purging of the cooling fluid and / or ambient air from the compressor 32 (e.g., working fluid side of the compressor) is performed.

[0050] With the foregoing in mind, FIG. 6 is a cross-sectional side view of an embodiment of a portion of the compressor 32 (e.g., non-hermetic compressor), illustrating an embodiment of the sealing system 102 (e.g., labyrinth seal system, venting system), in accordance with an aspect of the present disclosure. In particular, the sealing system 102 may include the one or more seals 104 (e.g., labyrinth seals, vents) disposed within the housing 106 of the compressor 32 and / or within the motor housing 112. In some embodiments, the sealing system 102 may include multiple seals 104 that are coupled to one another (e.g., as a single unit or component). Additionally or alternatively, some embodiments of the sealing system 102 may include multiple seals 104 that are disposed within the housing 106 and / or motor housing 112 separate from one another. The seals 104 may be disposed along one or more passages 162 (e.g., conduit, ducts, channels, flow paths, cavities, formed in the housing 106 and / or the motor housing 112) extending between the impeller cavity 128 and an environment surrounding the compressor 32, between the motor cavity 110 and the environment surrounding the compressor 32, and / or between the impeller cavity 128 and the motor cavity 110. In some embodiments, the seals 104 may be disposed along (e.g., within) a portion (e.g., length, dimension, cross-section) of the one or more passages 162 as a single unit. In some embodiments, the seals 104 may be disposed along separate portions of the one or more passages 162. For example, one or more of the seals 104 may extend along or be disposed within a first portion of the one or more passages 162, and one or more additional seals 104 may extend along or be disposed within a second portion the one or more passages 162 and / or may extend along or be disposed within another passage 162 of the one or more passages 162. In some embodiments, the seals 104 may extend along an entire dimension (e.g., length, width, cross-section) of the one or more passages 162. Additionally or alternatively, each passage 162 of the one or more passages 162 may include one of the seals 104 disposed therein. One or more seals 104 may occupy a portion of a cross-sectional area (e.g., relative to a flow of fluid therethrough) of one of the passages 162 and / or one or more seals 104 may occupy an entirety of the cross-sectional area of one of the passages 162.

[0051] By way of example, FIG. 6 illustrates a first passage 180 (e.g., first flow path) extending from and fluidly exposing (e.g., fluidly coupling) the impeller cavity 128 to the environment surrounding the compressor 32 (e.g., environment external to the compressor housing 106). The first passage 180 may be configured to direct a flow (e.g., a portion) of working fluid (e.g., water, steam) from the impeller cavity 128 toward the environment surrounding the compressor 32. In addition, the compressor 32 includes a second passage 182 (e.g., second flow path) extending from and fluidly exposing (e.g., fluidly coupling) the motor cavity 110 to the environment surrounding the compressor 32. The second passage 182 may be configured to direct a flow of motor cooling fluid (e.g., water, air) from the motor cavity 110 toward the environment surrounding the compressor 32. In some embodiments, the first passage 180 and the second passage 182 may be fluidly coupled to a third passage 184 (e.g., third flow path). The third passage 184 be configured to fluidly expose (e.g., fluidly couple) both the first passage 180 and the second passage 182 to the environment surrounding the compressor 32. In other words, the third passage 184 may extend from the first passage 180, the second passage 182, or both to the environment surrounding the compressor 32 to fluidly couple the first passage 180 and the second passage 182 to the environment surrounding the compressor 32. During operation of the compressor 32 (e.g., operation to circulate the working fluid through the heat pump system 100 in order to satisfy a load on the heat pump system 100), a portion of the working fluid directed from the impeller cavity 128 and through the first passage 180 and / or the flow of the motor cooling fluid directed from the motor cavity 110 and through the second passage 182 may flow into the third passage 184 prior to being discharged from the compressor 32. The third passage 184 may be fluidly coupled to a discharge port 186 (e.g., discharge vent, vent, venting outlet) of the housing 106. From the third passage 184, the portion of the working fluid and / or the flow of the motor cooling fluid may flow into the environment surrounding the compressor 32 via the discharge port 186. As such, during normal operation of the compressor 32 (e.g., to satisfy a heating and / or cooling load), a flow of the working fluid may be directed from the impeller cavity 128, along the first passage 180, along the third passage 184, and be discharged, via discharged port 186, from the compressor 32 to the environment surrounding the compressor 32. Additionally or alternatively, during normal operation of the compressor 32, a flow of the motor cooling fluid may be directed from the motor cavity 110, along the second passage 182, along the third passage 184, and be discharged, via the discharge port 186, from the compressor 32 (e.g., motor 50) to the environment surrounding the compressor 32.

[0052] It should be appreciated that, although FIG. 6 illustrates the first passage 180 and the second passage 182 as both fluidly coupled to the third passage 184, such that the flow of the working fluid and the flow of the motor cooling fluid may mix within the third passage 184 prior to being discharged from the compressor 32 (e.g., via the discharge port 186, via a common discharge port), in some embodiments, the first passage 180 fluidly coupled to the impeller cavity 128 and the second passage 182 fluidly coupled to the motor cavity 110 may be fluidly coupled to the environment surrounding the compressor 32 via separate discharge ports. That is, the first passage 180 may extend from the impeller cavity 128 to a first discharge port distinct from (e.g., separate from) a second discharge port that fluidly couples the second passage 182 to the motor cavity 110. Thus, the flow of working fluid may be directed from the impeller cavity 128 and along the first passage 180 to be discharged from the compressor 32 via the first discharge port, and the flow of motor cooling fluid may be directed from the motor cavity 110 and along the second passage 182 to be discharged from the compressor 32 (e.g., motor 50) via the second discharge port (e.g., a separate discharge port from the first discharge port).

[0053] In the manner described above, the sealing system 102 may enable venting of working fluid (e.g., steam) from the impeller cavity 128 to the environment surrounding the compressor 32, the sealing system 102 may enable venting (e.g., circulation) of motor cooling fluid (e.g., air, compressed air) from the motor cavity 110 to the environment surrounding the compressor 32, or both. The sealing system 102 may also enable blockage of working fluid flow from the impeller cavity 128 to the motor cavity 110. Similarly, the sealing system 102 may enable blockage of motor cooling fluid flow from the motor cavity 110 to the impeller cavity 128. As illustrated in FIG. 6, the sealing system 102 includes a first seal 164 (e.g., first labyrinth seal) disposed along a portion of the first passage 180. Thus, the first seal 164 may be fluidly exposed to the impeller cavity 128. The first seal 164 may be disposed along a flow path 170 (e.g., a first flow path, working fluid flow path) extending from the impeller cavity 128 to the discharge port 186 of the housing 106 of the compressor 32. The sealing system 102 also includes a second seal 166 (e.g., second labyrinth seal) disposed along an additional portion of the first passage 180. The second seal 166 is also disposed along the flow path 170.

[0054] The first passage 180 further includes an intermediate cavity 168 disposed between the portion of the first passage 180 that includes the first seal 164 and the additional portion of the first passage 180 that includes the second seal 166. The intermediate cavity 168 may be a gap (e.g., space) formed within the housing 106 of the compressor 32 between the portion of the first passage 180 that includes the first seal 164 and the additional portion of the first passage 180 that includes the second seal 166. In some operations, a portion of the working fluid (e.g., steam) within the impeller cavity 128 may flow along the flow path 170 to the discharge port 186 and may be discharged from the housing 106 of the compressor 32. That is, a portion of the working fluid within the impeller cavity 128 may flow along the flow path 170, across the first seal 164, into the intermediate cavity 168, across the second seal 166, and out of the housing 106 via the discharge port 186. A pressure of the working fluid within the intermediate cavity 168 may be different than (e.g., higher, lower) or substantially similar to a pressure of the working fluid within the impeller cavity 128. In addition, a pressure of working fluid within the intermediate cavity 168 may be different than (e.g., higher, lower) or substantially similar to a pressure of the environment surrounding the compressor 32 (e.g., a pressure exposed to an outlet or opening of the discharge port 186 of the housing 106).

[0055] It should be appreciated that pressure differences between the impeller cavity 128 and the intermediate cavity 168 and / or between the intermediate cavity 168 and the environment surrounding the compressor 32 may vary, such as based on operating parameters of the compressor 32, operating conditions of the compressor 32, ambient conditions in the environment surrounding the compressor 32, other factors or variables, or any combination thereof. During operation of the compressor 32 to satisfy a heating and / or cooling demand of a load of the heat pump system 100 (e.g., during normal operating speeds of the compressor 32), a portion of the working fluid (e.g., steam) within the impeller cavity 128 may travel from the impeller cavity 128 and along the flow path 170, through the first passage 180, across the first seal 164, into the intermediate cavity 168, across the second seal 166, through the third passage 184, and out of the compressor 32 into the environment via the discharge port 186. In such instances, a first pressure within the impeller cavity 128 may be greater than a second pressure within the intermediate cavity 168, and the second pressure within the intermediate cavity 168 may be greater than a third pressure within the environment surrounding the compressor 32.

[0056] In some embodiments, the sealing system 102 also may include a third seal 188 (e.g., third labyrinth seal) disposed along a portion of the second passage 182. The third seal 188 may therefore be fluidly exposed to the motor cavity 110. The third seal 188 may be disposed along an additional flow path 174 (e.g., a second flow path, motor cooling fluid flow path) extending from the motor cavity 128 to the discharge port 186 of the housing 106 of the compressor 32 (e.g., motor 50). In some operations, a portion of the motor cooling fluid (e.g., air) within the motor cavity 110 may flow along the additional flow path 174 to the discharge port 186 and may be discharged from the housing 106 of the compressor 32. That is, at least a portion of the motor cooling fluid may flow across the third seal 188 and out of the housing 106 via the discharge port 186. A pressure of the motor cooling fluid within the motor cavity 110 may be different than (e.g., higher, lower) or substantially similar to a pressure of the environment surrounding the compressor 32 (e.g., a pressure exposed to an outlet or opening of the discharge port 186 of the housing 106). It should be appreciated that pressure differences between the motor cavity 110 and the intermediate cavity 168 and / or between the intermediate cavity 168 and the environment surrounding the compressor 32 may vary, such as based on operating parameters of the compressor 32, operating conditions of the compressor 32, operating conditions of the motor 110, operating parameters of a cooling system of the motor 110, ambient conditions in the environment surrounding the compressor 32, other factors or variables, or any combination thereof. During operation of the compressor 32 to satisfy a heating and / or cooling demand of a load (e.g., conditioning load, heating load, cooling load) of the heat pump system 100 (e.g., during normal operating speeds of the compressor 32), motor cooling fluid (e.g., air) may travel from the motor cavity 110 and along the additional flow path 174, through the second passage 180, across the third seal 188, through the third passage 184, and out of the compressor 32 into the environment via the discharge port 186.

[0057] It should be appreciated that, although FIG. 6 illustrates the sealing system 102 as including the first, second, and third passages 180, 182, 184, the first, second, third seals 164, 166, 188, the intermediate cavity 168, and the discharge port 186, in some embodiments, the sealing system 102 of the compressor 32 may include other suitable respective numbers of passages, seals, cavities, discharge ports, or any combination thereof, such as to enable venting of the impeller cavity 128 and / or the motor cavity 110 (e.g., into the environment surrounding the compressor 32) during operation of the compressor 32.

[0058] Continuing with FIG. 6, during operation of the compressor 32 to satisfy a heating and / or cooling demand of a load of the heat pump system 100 (e.g., during normal operating speeds of the compressor 32), the working fluid may be pressurized within the impeller cavity 128 (e.g., via rotation of the impeller 126). In some instances, a pressure (e.g., of the working fluid) within the intermediate cavity 168 may be lower than a pressure (e.g., of the working fluid) within the impeller cavity 128, and a pressure of the environment surrounding the compressor 32 (e.g., atmospheric pressure) may be lower than the pressure of the working fluid within the intermediate cavity 168. As a result, a portion of working fluid from the impeller cavity 128 may be directed (e.g., via a pressure differential, differences in pressures) along the flow path 170 towards the environment surrounding the compressor 32. In addition, during operation of the compressor 32 to satisfy a heating and / or cooling demand of a load of the heat pump system 100 (e.g., during normal operating speeds of the compressor 32), motor cooling fluid (e.g., ambient air, pressurized air) may be circulated through the motor housing 112 to enable cooling of the motor 50. A portion or all of the motor cooling fluid (e.g., air) may be discharged from the motor housing 112 via the discharge port 186 of the compressor 32 discussed above. In other words, the discharge port 186 may be configured to discharge working fluid received from the impeller cavity 128 via the flow path 170, and the discharge port 186 may be configured to discharge motor cooling fluid received from the motor cavity 110 via the flow path 174 (e.g., additional flow path, second flow path, motor cooling fluid flow path). The flow path 170 extending from the impeller cavity 128 to the discharge port 186 and the additional flow path 174 extending from the motor cavity 110 to the discharge port 186 may also be fluidly coupled to one another (e.g., via the third passage 184, upstream of the discharge port 186). During operation of the compressor 32, a pressure of motor cooling fluid (e.g., air) within the motor cavity 110 may be lower than the pressure of the working fluid along the flow path 170 (e.g., within the intermediate cavity 168). As such, the pressure of working fluid along the flow path 170 may block flow of the motor cooling fluid (e.g., air) from the motor cavity 110 into the impeller cavity 128 (e.g., via the flow path 170). Thus, the motor cooling fluid may not flow into the working fluid circuit of the heat pump system 100 during normal operation of the compressor 32. Additionally or alternatively, the motor cooling fluid may be circulated through the motor cavity 110 at an elevated pressure (e.g., a pressure greater than atmospheric pressure). In this way, the motor cooling fluid may flow through the motor cavity 110 and out of the discharge port 186 (e.g., along the additional flow path 174), which may enable blockage of flow of the working fluid flow from the flow path 170 and into the motor cavity 110 via the additional flow path 174.

[0059] In some applications of the heat pump system 100, operation of the compressor 32 may be reduced or suspended. In other words, the compressor 32 may be operated at a reduced capacity (e.g., reduced speed, reduced number of operating compressor stages) and / or the compressor 32 may be shut down. For example, operation of the compressor 32 may be suspended during time periods in which a demand for heating and / or cooling by the heat pump system 100 does not exist (e.g., a call for conditioning is absent or inactive and / or a heating or cooling demand is absent or inactive) or after a demand for heating and / or cooling is satisfied by the heat pump system 100. During reduced and / or suspended operation of the compressor 32, a temperature (e.g., saturation temperature) of the working fluid within the impeller cavity 128 may decrease (e.g., below 100°C). As a result, a pressure of the working fluid within the impeller cavity 128 may decrease (e.g., below 1 bar, below 1.1 bar). When pressure of the working fluid within the impeller cavity 128 decreases, a pressure (e.g., working fluid pressure) within the intermediate cavity 168 may also decrease. Thus, motor cooling fluid (e.g., air, non-condensable air) within the motor cavity 110 may be susceptible to migration (e.g., due to a pressure gradient) from the motor cavity 110 and towards the impeller cavity 128 of the compressor 32. For example, during instances in which the pressure within the intermediate cavity 168 and / or impeller cavity 128 fall below a pressure of the motor cooling fluid within the motor cavity 110, migration of the motor cooling fluid from the motor cavity 110, along the additional flow path 174, along the flow path 170, and into the impeller cavity 128 may be induced. In some instances (e.g., during shutdown or suspended operation of the compressor 32), the pressure (e.g., of the working fluid) within the impeller cavity 128 may additionally or alternatively be less than a pressure of an environment surrounding the compressor 32 (e.g., atmospheric pressure), which may similarly induce migration of atmospheric or ambient air into the impeller cavity 128 via the discharge port 186 and the flow path 170. Introduction of air (e.g., motor cooling fluid, ambient air) into the impeller cavity 128 (e.g., mixed with the working fluid) may cause inefficiencies in the heat pump system 100. Indeed, presence of non-condensable air within the impeller cavity 128 may prompt purging of the compressor 32 and / or working fluid circuit prior to resuming operation of the compressor 32 (e.g., to satisfy a heating and / or cooling load). Thus, restart of the compressor 32 may be delayed, and therefore operation of the heat pump system 100 to satisfy a subsequent demand for heating or cooling may be delayed.

[0060] In accordance with the present techniques, components of the heat pump system 100 (e.g., compressor 32) may be controlled via the control system 150 (e.g., controller, automation controller), as described above with reference to FIG. 5. For example, the control system 150 may be configured to control operation of the compressor 32 (e.g., one or more components of the compressor 32, the motor 50, etc.) to enable more efficient operation of the compressor 32, and thus more efficient operation of the heat pump system 100. The control system 150 may be configured to control operation of the compressor 32 and / or other components of the heat pump system 100 to block undesired or unintended fluid migration between the impeller cavity 128 and the motor cavity 110, such as during instance in which the heat pump system 100 is not operating to satisfy a cooling and / or heating demand. In particular, as discussed in more detail below, the control system 150 may be configured to operate the heat pump system 100 (e.g., compressor 32) in a standby operating mode during periods in which the compressor 32 is not otherwise operated (e.g., to satisfy a heating and / or cooling demand of a load of the heat pump system 100, operated above a threshold operating speed). In other words, during operation of the compressor 32 in the standby mode, a call for conditioning on the heat pump system 100 and / or a load demand on the heat pump system 100 may be absent. Additionally or alternatively, the control system 150 may be configured to control operation of the heat pump system 100 (e.g., compressor 32) based on feedback received from the one or more sensors 160 of the heat pump system 100, as described above with reference to FIG. 5. As illustrated in FIG. 6, one or more of the sensors 160 may be positioned (e.g., located) within the impeller cavity 128, along a suction inlet of the compressor 32, along a discharge outlet of the compressor 32, the intermediate cavity 168, the environment surrounding the compressor 32, the motor cavity 110, another suitable location, or any combination thereof. For example, one or more of the sensors 160 may be configured to detect a pressure within a respective location of the sensor 160 (e.g., working fluid pressure, motor cooling fluid pressure, ambient pressure, working fluid suction pressure, working fluid discharge pressure) and to provide data indicative of the detected pressures to the control system 150 (e.g., controller). In some embodiments, one or more sensors 160 may be configured to detect an operating parameter of the compressor 32 and / or motor 50, such as an operating speed (e.g., rotational speed), a temperature, an operating mode, an operating capacity, another suitable operating parameter, or any combination thereof.

[0061] In the standby operating mode, the control system 150 may operate the heat pump system 100 (e.g., compressor 32) to increase and / or maintain a temperature and / or a pressure of the working fluid, such as above a threshold level (e.g., a threshold pressure level, a pressure value greater than an ambient pressure value). For example, the control system 150 may operate the compressor 32 (e.g., motor 50) in the standby operating mode to maintain a temperature and / or a pressure of the working fluid (e.g., water, steam, within the impeller cavity 128, along the flow path 170) at and / or above a corresponding threshold level. In other words, the control system 150 may operate the compressor 32 at a speed (e.g., low speed, lower limit speed, minimum allowable speed) that achieves or causes the working fluid (e.g., within the impeller cavity 128) to have a desired temperature and / or a desired pressure. In some embodiments, the compressor 32 may be a multi-stage compressor that includes multiple stages (e.g., compressor stages, operating stages, arranged in series). The control system 150 may operate the compressor 32 in the standby operating mode by operating and / or maintaining operation of a reduced number of compressor stages to increase and / or maintain a temperature and / or a pressure of the working fluid within the compressor 32 above the threshold level. As such, in some embodiments, the control system 150 may operate the compressor 32 in the standby mode by operating and / or maintaining operation of a fewer number of operating compressor stages (e.g., 1, 2), such as operating a single compressor stage, as compared to a number of operating compressor stages (e.g., 2, 3, 4) operated and / or maintained operating by the control system 150 during normal operation of the compressor 32.

[0062] In some embodiments, the control system 150 may be configured to select a particular operating speed, to control the compressor 32 to operate at a particular operating speed, and / or to control a number of operating compressor stages of the compressor 32 based on feedback from one or more of the sensors 160 to cause the working fluid within the compressor 32 to maintain a pressure equal to or greater than a threshold value. For example, one of the sensors 160 may include a pressure sensor configured to detect a pressure of the working fluid within the impeller cavity 128 and / or along the flow path 170. In some embodiments, the threshold value (e.g., threshold pressure) may correspond to (e.g., may be based on) a pressure that is substantially equal to or greater than an ambient pressure (e.g., detected by one of the sensors 160), a pressure of motor cooling fluid circulated through the motor cavity 110 (e.g., detected by one of the sensors 160), a temperature of the working fluid, an ambient temperature, or other suitable value. In some embodiments, the threshold value (e.g., working fluid pressure threshold value) may be dynamic (e.g., adjusted), for example, based on feedback from one of the sensors 160. For example, the control system 150 may be configured to increase the threshold value of the working fluid based on feedback indicative of an increase in a pressure of the motor cooling fluid and / or an increase in a pressure of an ambient environment surrounding the compressor 32. Similarly, the control system 150 may be configured to decrease the threshold value of the working fluid based on feedback indicative of a decrease in a pressure of the motor cooling fluid and / or a decrease in a pressure of an ambient environment surrounding the compressor 32. In other embodiments, the threshold value may be a predetermined value, such as a predetermined value associated with an upper limit value of an expected cooling fluid pressure and / or an upper limit value of an expected ambient air pressure.

[0063] The control system 150 may be further configured to operate the compressor 32 (e.g., motor 50) in order to achieve and / or maintain a pressure of the working fluid within the impeller cavity 128 that is equal to or greater than the threshold value. In some embodiments, the memory 156 of the control system 150 may store a plurality of threshold values (e.g., working fluid pressure values) with corresponding operating parameter values (e.g., operating speeds, operating stages, operating capacities) of the compressor 32 that achieve a pressure of the working fluid at or above the associated threshold value. Additionally or alternatively, the control system 150 may be configured to dynamically adjust operation of the compressor 32 based on data received from the one or more sensors 160 to cause the working fluid within the impeller cavity 128 and / or other portion of the heat pump system 100 to achieve and / or remain at or above the threshold value (e.g., which may correspond to and / or may be greater than an ambient pressure and / or motor cooling fluid pressure detected by one or more of the sensors 160). As the control system 150 operates the compressor 32 in the standby operating mode (e.g., at a speed and / or capacity associated with the threshold value), the pressure of the working fluid may increase to the threshold value to enable flow of a portion of the working fluid through the sealing system 102 (e.g., along the flow path 170) and out of the housing 106 of the compressor 32 via the discharge port 186. In this way, migration of air (e.g., motor cooling fluid, ambient air) into the impeller cavity 128 may be blocked via flow of the portion of the working fluid through the sealing system 102.

[0064] In addition to, or instead of, operation of the compressor 32 in the standby operating mode, the HVAC&R system 10 (e.g., via the control system 150) may operate to supply heat to the working fluid within the heat pump system 100 (e.g., working fluid circuit, compressor 32) during non-operation, standby, and / or shutdown of the compressor 32. For example, the HVAC&R system 10 may include one or more components that may be operated to apply and / or transfer heat to the working fluid within the heat pump system 100. In this way, a temperature and / or pressure of the working fluid may be maintained at or above the threshold level, which may enable blockage of air (e.g., motor cooling fluid, ambient air) migration into the impeller cavity 128 of the compressor 32 (e.g., via the flow path 170, from the motor cavity 110, from the ambient environment).

[0065] With the foregoing in mind, FIG. 7 is a schematic of an embodiment of the HVAC&R system 10, illustrating an embodiment of the heat pump system 100 including a heating system 200, in accordance with an aspect of the present disclosure. The heat pump system 100 may be similar to and / or may include similar components as the vapor compression system 14 described above with reference to FIGS. 3 and 4. For example, the heat pump system 100 may include a first heat exchanger 202 (e.g., evaporator 38), a second heat exchanger 204 (e.g., condenser), a compressor 206 (e.g., compressor 32), and an expansion valve 208 (e.g., expansion valve 36) disposed along a working fluid circuit 210. Indeed, the compressor 206 of the illustrated embodiment may include one or more of the components discussed above with reference to FIGS. 5 and 6, such as the motor 50 and the sealing system 102. The components of the heat pump system 100 may be disposed along the working fluid circuit 210 via pipes, plumbing, conduits, tubing, and so forth. The working fluid circuit 210 may enable the heat pump system 100 (e.g., the vapor compression system 14) to circulate a working fluid (e.g., water, steam) through the components of the heat pump system 100 to cool and / or heat one or more conditioning fluids or cooling fluids (e.g., air, water, brine, glycol, etc.). In particular, as similarly discussed above, the first heat exchanger 202 and the second heat exchanger 204 may each be configured to receive the working fluid directed along the working fluid circuit 210, to receive a respective flow of conditioning or cooling fluid, and to place the working fluid in a heat exchange relationship with the flow of conditioning fluid or cooling fluid.

[0066] In addition, the HVAC&R system 10 may include the heating system 200 configured to supply heat to the heat pump system 100 (e.g., to the working fluid of the heat pump system 100). One or more of the heating system 200 may be located as any suitable location associated with the heat pump system 100 to enable heating of the working fluid via operation of the heating system 200. For example, in some embodiments, the heating system 200 may include an electric heater, a ceramic heater, a resistive heater, a heating blanket, a heating element a gas heater, a heat exchanger configured to circulate a heating fluid, an infrared heater, another suitable type of heater, or any combination thereof. Additionally or alternatively, in some embodiments, the heating system 200 may include a circulation pump associated with the first heat exchanger 202, the second heat exchanger 204, the working fluid circuit 210, or other portion of the heat pump system 100. For example, operation of the circulation pump may produce thermal energy (e.g., via a motor of the circulation pump) and may supply heat to the working fluid within the first heat exchanger 202, the second heat exchanger, and / or the working fluid circuit 210 (e.g., within respective process piping of the first heat exchanger 202, the second heat exchanger, and / or the working fluid circuit 210). In some applications, the heating system 200 may be implemented and operated in the standby operating mode (e.g., instead of the compressor 206), accordance with the present techniques, to reduce or limit short cycle operation of the compressor 206.

[0067] As illustrated in FIG. 7, the heating system 200 may be positioned at or associated with the first heat exchanger 202 (e.g., evaporator 38), at or associated with a portion of the working fluid circuit 210 (e.g., a conduit) fluidly coupling the first heat exchanger 202 to the compressor 206, at or associated with a portion of the working fluid circuit 210 (e.g., a conduit) fluidly coupling the expansion valve 208 to the first heat exchanger 202, at or associated with the second heat exchanger 204 (e.g., condenser 34), at or associated with a portion of the working fluid circuit 210 (e.g., a conduit) fluidly coupling the second heat exchanger 204 to the expansion valve 208, at or associated with a portion of the working fluid circuit 210 (e.g., a conduit) fluidly coupling the compressor 206 to the second heat exchanger 204, or any combination thereof. In some embodiments, the heating system 200 may be configured to transfer heat to the compressor 206 to enable heating of the working fluid within the working fluid circuit 210. For example, the heating system 200 may include a heating element (e.g., electric heating element) coupled to (e.g., attached, fixed, secured) to one or more of the components of the working fluid circuit 210, piping of the working fluid circuit 210 (e.g., upstream of the compressor 206), the housing 106 of the compressor 206, or any combination thereof. Operation of the heating system 200 may also be controlled via the control system 150. In particular, in some embodiments, the heating system 200 may be configured to provide heat to the heat pump system 100 based on feedback from one or more of the sensors 160 indicative of an operating parameter (e.g., operating parameter value) of the heat pump system 100 (e.g., a pressure of the ambient environment, a pressure of the working fluid, a pressure of the motor cooling fluid), feedback and / or data indicative of an operational state of the heat pump system 100 (e.g., compressor 32, 206), another suitable input, or any combination thereof. In accordance with present techniques, the control system 150 may operate the heating system 200 to transfer heat to the working fluid within the working fluid circuit 210 (e.g., compressor 206) during non-operation, shutdown, and / or standby operation of the compressor 206. As discussed above, during reduced and / or suspended operation of the compressor 206 (e.g., when a load or demand on the heat pump system 100 does not exist) a temperature and / or pressure of the working fluid circulated through the working fluid circuit 210 may fall below a threshold level or threshold value (e.g., corresponding to a pressure of the motor cooling fluid and / or a pressure of the ambient environment). In such instances, the compressor 206 may be susceptible to ingress of a fluid, such as air (e.g., non-condensable air, ambient air, motor cooling fluid), via the sealing system 102. As similarly discussed above, during periods in which the compressor 206 is not operated (e.g., to satisfy a heating and / or cooling demand of a load of the heat pump system 100), the control system 150 may operate the heating system 200 (e.g., activate a heating element) to apply or transfer heat to the working fluid and increase a temperature and / or a pressure of the working fluid to maintain the temperature and / or pressure above the threshold level (e.g., atmospheric pressure, motor cooling fluid pressure). With the pressure of the working fluid at or above the threshold level, a portion of the working fluid may flow through the sealing system 102 (e.g., along the flow path 170) and out of the housing 106 of the compressor 32 via the discharge port 186. In this way, migration of air (e.g., motor cooling fluid, ambient air) into the impeller cavity 128 may be blocked via flow of the working fluid through the sealing system 102 at or above the threshold level (e.g., threshold pressure).

[0068] FIG. 8 illustrates a flow diagram of an embodiment of a method 300 (e.g., control logic, control scheme) for operating the HVAC&R system 10 in a standby mode (e.g., standby operating mode), in accordance with an aspect of the present disclosure. The method 300 may be utilized during time periods (e.g., stages, phases) during which operation of the compressor 32, 206 is suspended, a speed of the compressor 32, 206 is reduced, and / or a number of operating compressor stages is reduced. A subset and / or all of the steps of the method 300 described below may be implemented and / or performed by the control system 150 of the heat pump system 100 and / or by another control system. In other words, the control system 150 (e.g., a single control system, the processing circuitry 154) may be configured to implement and / or execute the method 300 to control various components of the heat pump system 100 (e.g., vapor compression system 14, compressor 32, 206) and / or the heating system 200. In other embodiments, the method 300 may be implemented by another control system (e.g., a dedicated control system of the compressor 32, 206), more than one control system, or other suitable control system. In certain embodiments, the method 300 may be used to control operation of an embodiment of the compressor 32 (e.g., a compressor system) having two or more stages (e.g., operating stages, stages of compression). It should also be noted that additional steps may be performed with respect to the method 300. Moreover, certain steps of the method 300 may be omitted, modified, and / or performed in a different order.

[0069] As mentioned above, the method 300 may be implemented (e.g., via the control system 150) to control components of the HVAC&R system 10 (e.g., the heat pump system 100 and / or the heating system 200) during periods in which the compressor 32, 206 is not operating (e.g., not powered) and / or is operated at a reduced capacity. More specifically, the method 300 may be executed during periods in which the compressor 32, 206 is susceptible to ingress of a fluid (e.g., air, non-condensable air), such as motor cooling fluid or ambient air via the sealing system 102 (e.g., flow path 170). In some applications, the method 300 may be executed (e.g., via the control system 150) based on an indication of an operational state of the heat pump system 100 (e.g., the compressor 32, 206), such as an indication that the compressor 32 is not operating (e.g., a heating or cooling demand of a load is absent) and / or an indication that the compressor 32 is operating at a reduced capacity or speed (e.g., a speed or capacity below a threshold level). Additionally or alternatively, the method 300 may be implemented in response to detected pressures and / or temperatures of the working fluid (e.g., within the compressor 32, within the heat pump system 100) being below a target or threshold pressure and / or target or threshold temperature (e.g., threshold pressure range or value, threshold temperature range or value) of the working fluid within the heat pump system 100. In some embodiments, the threshold pressure value may correspond to a pressure of ambient air and / or a pressure of motor cooling fluid (e.g., air, compressed air) circulated through the motor cavity 110 (e.g., detected by one or more sensors 160).

[0070] As similarly described above, execution of the method 300 may initiate operation of the compressor 32 and / or the heating system 200 to cause a pressure and / or temperature of the working fluid within the heat pump system 100 to increase, thereby achieving and / or maintaining the pressure and / or temperature of the working fluid at the threshold pressure level and / or threshold temperature level. As such, execution of the method 300 may reduce and / or block flow of motor cooling fluid (e.g., air, non-condensable air) from the motor cavity 110 of the motor 50 into the impeller cavity 128 (e.g., thereby avoiding mixing of the motor cooling fluid with the working fluid within the heat pump system 100) of the compressor 32, 206 (e.g., via the sealing system 102). Similarly, execution of the method 300 may reduce and / or block flow of ambient air into the impeller cavity 128 via the discharge port 186 and the sealing system 102. Thus, the method 300 may enable more efficient operation of the HVAC&R system 10 (e.g., heat pump system 100) during varying conditions, stages, and / or phases of the compressor 32 and / or heat pump system 100 (e.g., suspended operation of the compressor 32, reduced operation of the compressor 32, initial startup of the compressor 32).

[0071] Though the method 300 is illustrated as a series of steps, it should be understood that the method 300 and the steps thereof may be executed or implemented as a continual or continuous control loop (e.g., a proportional integral derivative [PID] control loop), such as based on any suitable input, data, or feedback (e.g., feedback from the sensors 160). That is, the steps of the method 300 may be repeatedly executed (e.g., in sequential order, one or more steps simultaneously) to enable operation of the HVAC&R system 10 to operate in the standby mode or a normal mode (e.g., normal operating speeds of compressor 32, 206 during operation to satisfy a heating and / or cooling demand of a load of the heat pump system 100). Indeed, the method 300 may be continually or continuously executed to dynamically control components of the HVAC&R system 10 in real time (e.g., based on feedback provided by one or more of the sensors 160) to more reliably block, reduce, and / or mitigate undesired fluid migration to and / or from the compressor 32 and the motor 50.

[0072] In the illustrated embodiment, the method 300 begins with the HVAC&R system 10 (e.g., control system 150) receiving an indication of an operational condition of the HVAC&R system 10, as indicated by block 302. In some embodiments, the indication may be associated with a detected operating parameter value of the HVAC&R system 10, such as a pressure value and / or a temperature value of the working fluid (e.g., within the compressor 32, upstream of the compressor 32, along a working fluid circuit of the heat pump system 100). In some embodiments, the step at block 302 may include a comparison of the detected operating parameter value with a threshold operating parameter value or range of values (e.g., a lower limit value). For example, the control system 150 may receive data from the sensor 160 indicative of a detected pressure value and / or a detected temperature value of the working fluid within the heat pump system 100. The control system 150 may compare the detected pressure value and / or detected temperature value to a respective threshold pressure value and / or a threshold temperature value (e.g., a value associated with the motor cooling fluid and / or the ambient atmosphere) to determine the operational condition of the HVAC&R system 10. Additionally or alternatively, the operational condition may be indicative of an operational state of the heat pump system 100 and / or a component of the heat pump system 100, such as the compressor 32. For example, the operational condition may be indicative of a shutdown of the compressor 32 and / or non-operation (e.g., suspended operation) of the compressor 32 to circulate the working fluid in order to satisfy a heating load and / or a cooling load on the HVAC&R system 10.

[0073] In some embodiments, the operational condition of the HVAC&R system 10 may indicate that the heat pump system 100 (e.g., compressor 32, 206) is operating under normal operational conditions (e.g., compressor 32 operating at speeds above a threshold value, compressor 32 is operating in response to a call for heating and / or cooling). For example, the control system 150 may determine that the detected pressure value and / or the detected temperature value of the working fluid is within a threshold pressure range and / or a threshold temperature range (e.g., at or above a threshold pressure value and / or a threshold temperature value). Based on such a determination, the method 300 may proceed to block 304, whereby the control system 150 may continue operating the HVAC&R system 10 in a normal operational mode (e.g., under normal operational conditions) based on the indication. Additionally or alternatively, in some embodiments, the indication of the operational condition of the HVAC&R system 10 may be based on feedback from one or more sensors 160 of the HVAC&R system 10, such as feedback indicative of a speed of the compressor 32, 206 received from a speed sensor associated with the compressor 32, 206, feedback indicative of a flow rate of the working fluid from one or more flow rate sensor associated with the heat pump system 100, an indication of a call for heating or cooling received by the HVAC&R system 10, and so forth. In some embodiments, the indication of the operational condition of the HVAC&R system 10 may be based on input received via the interface 152 of the control system 150 (e.g., user input) and / or operational control logic stored in the memory 156 of the control system 150 and executed by the processing circuitry 154.

[0074] Furthermore, in some embodiments, the operational condition of the HVAC&R system 10 may be indicative of the heat pump system 100 (e.g., compressor 32, 206) operating at a low or reduced capacity (e.g., reduced speed of the compressor 32, lower than a threshold speed associated with normal operating conditions), suspended operation of the heat pump system 100 (e.g., operation of the compressor 32, 206 is suspended), and / or operation of the compressor 32 with a reduced number of operating compressor stages (e.g., as compared to a number of operational compressor stages associated with normal operation of the heat pump system 100). In such instances, the operational condition may be associated with periods in which the heat pump system 100 does not operate to satisfy a load or demand on the heat pump system 100. For example, the control system 150 may determine that the detected pressure value and / or the detected temperature value of the working fluid is not within a threshold pressure range and / or a threshold temperature range (e.g., the detected value at or below a threshold value). Additionally or alternatively, in some embodiments, an indication that the heat pump system 100 (e.g., the compressor 32, 206) is operating at a reduced capacity (e.g., compressor 32 operating at a low speed, a speed below a threshold value, and / or compressor 32 operating with a reduced number of operating compressor stages) and / or that operation of the heat pump system 100 is suspended (e.g., compressor 32, 206 is not operating) may be based on feedback from other sensors 160 of the HVAC&R system 10. To this end, one or more of the sensors 160 may be configured to transmit feedback to the control system 150 indicative of such a detected speed of the compressor 32, 206, a detected flow rate of the working fluid, a control signal provided to the motor 50 (e.g., via the control system 150) and so forth. In some instances, the control system 150 may be configured to compare the feedback (e.g., operating parameter value) to a corresponding threshold value. In some embodiments, the indication that the heat pump system 100 (e.g., compressor 32, 206) is operating at a low speed, at a low capacity, and / or is not operating may be based on input received via the interface 152 of the control system 150 (e.g., user input) and / or operational control logic stored in the memory 156 of the control system 150 and implemented by the processing circuitry 154. For example, the input may be associated with an operational stage / phase of the heat pump system 100 in which a speed or capacity of the compressor 32, 206 is reduced and / or operation of the compressor 32, 206 is suspended.

[0075] Based on such a determination, the method 300 may proceed to block 306. At block 306, the control system 150 may operate the HVAC&R system 10 in a standby mode based on the indication. In particular, the control system 150 may operate one or more components of the heat pump system 100 and / or the heating system 200 to achieve and / or maintain a temperature and / or pressure of the working fluid (e.g., within the impeller cavity 128, along a working fluid circuit of the heat pump system 100) above a corresponding threshold value. In accordance with the present techniques, the method 300 may be executed to maintain a target pressure and / or a target pressure gradient or differential (e.g., between the pressure of the working fluid and a pressure of motor cooling fluid, between the pressure of the working fluid and an ambient pressure) across the sealing system 102. In this way, flow of motor cooling fluid (e.g., air) from the motor cavity 110 to the impeller cavity 128 (e.g., across the sealing system 102) may be blocked via flow of a portion of the working fluid across the sealing system 102 (e.g., to the discharge port 186) and / or via a pressure of the working fluid within the impeller cavity 128 that is greater than a pressure of the motor cooling fluid. In addition, flow of ambient air from an environment surrounding the compressor 32 to the impeller cavity 128 (e.g., via the discharge port 186 and the sealing system 102) may be blocked via flow of the working fluid across the sealing system 102 (e.g., to the discharge port 186) and / or via a pressure of the working fluid within the impeller cavity 128 that is greater than a pressure of the ambient air. In some embodiments, the control system 150 may operate the compressor 32, 206 (e.g., at a low speed, at a selected speed, with a number of operational stages, via control of the motor 50) to maintain a pressure of the working fluid above a threshold pressure level (e.g., threshold pressure value), and thereby maintain a desired pressure gradient or differential across the sealing system 102. The control system 150 may control the motor 50 to increase a speed of the compressor 32, 206 to reach a particular speed that causes the pressure of the working fluid to meet and / or exceed the threshold pressure level. In embodiments of the compressor 32 configured as a multi-stage compressor and / or as a multi-compressor system, the control system 150 may operate a selected number of stages and / or compressors (e.g., a subset of a total number) to cause the pressure of the working fluid to meet and / or exceed the threshold pressure level. For example, the control system 150 may operate (e.g., maintain operation of) a single stage of a multistage compressor to cause the pressure of the working fluid to meet and / or exceed the threshold pressure level. By reducing the speed of the compressor 32, 206 and / or reducing a number of stages of the compressor 32, 206 that are operating, energy consumption may be reduced while still providing heat to the heat pump system 100 (e.g., working fluid) to maintain the pressure of the working fluid at or above the threshold pressure level.

[0076] Additionally or alternatively, the method 300 may include operation of the heating system 200 in the standby operating mode of the HVAC&R system 10 (e.g., block 306). In some embodiments, the control system 150 may operate the heating system 200 in addition to, or instead of, operating the compressor 32 (e.g., at a low speed, at a reduced capacity) in the standby operating mode of the HVAC&R system 10 described herein. As discussed above, the control system 150 may operate the heating system 200 to provide heat to the working fluid within the heat pump system 100. Applying heat (e.g., saturation temperature) to the working fluid via the heating system 200 may increase the pressure of the working fluid, and thus the pressure of the working fluid within the compressor 32, 206. In this way, a pressure gradient or differential across the sealing system 102 may be maintained (e.g., working fluid pressure greater than ambient air pressure and / or working fluid pressure greater than motor cooling fluid pressure), which may enable blockage of fluid flow (e.g., air flow) into the impeller cavity 128 (e.g., from the motor cavity 110, from an ambient environment). The heating system 200 may include an electric heater, a resistive heater, a heating blanket, heating tape, and / or other suitable type of heater or heating system, which may be operatively coupled to (e.g., attached to) the compressor 32, the working fluid circuit (e.g., a conduit) of the heat pump system 100, and / or another component of the hat pump system 100 to which the working fluid is exposed. Additionally or alternatively, in some embodiments, the heating system 200 may include a circulation pump of the first heat exchanger 202, the second heat exchanger 204, and / or the working fluid circuit 210. For example, operation of a circulation pump may produce thermal energy (e.g., via a motor of the circulation pump) and may supply heat to the working fluid within the first heat exchanger 202, the second heat exchanger, and / or the working fluid circuit 210 (e.g., within respective process piping of the first heat exchanger 202, the second heat exchanger, or both).

[0077] At block 308, the control system 150 may receive an indication of an operating parameter (e.g., operating parameter value) of the heat pump system 100. For example, the control system 150 may be communicatively coupled to one or more sensors 160 and may be configured to receive data from the sensors 160 indicative of one or more operating parameter values. In some embodiments, the control system 150 may receive data indicative of a detected pressure value and / or a detected temperature value of the working fluid (e.g., from one or more sensors 160 associated with the compressor 32, 206). For example, the control system 150 may receive detected pressure values and / or detected temperature values of the working fluid within the impeller cavity 128 and / or the intermediate cavity 168 of the compressor 32, 206. At block 310, the control system 150 may compare the received operating parameter value to a threshold operating parameter value to determine whether the operating parameter value is equal to or greater than the threshold operating parameter value. For example, the control system 150 may compare a detected pressure value and / or a detected temperature value of the working fluid within the impeller cavity 128 and / or the intermediate cavity 168 with a target pressure value and / or target temperature value (e.g., a target pressure range, a target temperature range, a threshold pressure value) for working fluid within the impeller cavity 128 and / or the intermediate cavity 168. In some embodiments, the control system 150 may compare a detected pressure value and / or a detected temperature value of the working fluid within the impeller cavity 128 to a detected value of an ambient pressure and / or a pressure of motor cooling fluid within the motor cavity 110. In response to a determination that the operating parameter value meets or exceeds the threshold operating parameter value, the method 300 may return to block 302 and continue with the method 300 as discussed above. In some embodiments, in response to the detected operating parameter value meeting or exceeding the target operating parameter value, the control system 150 may suspend operation of the HVAC&R system 10 in the standby operating mode. Additionally or alternatively, the control system 150 may maintain operation of the HVAC&R system 10 in the standby operating mode to maintain a pressure of the working fluid at or above the threshold value. Furthermore, in response to a determination that the operating parameter value does not meet the target operating parameter value, the method 300 may return to block 306 and continue with the method 300 as discussed above. As such, the control system 150 may maintain operation of the HVAC&R system 10 in the standby operating mode and continue execution of blocks 308 and 310 until the detected operating parameter value meets or exceeds the target operating parameter value.

[0078] The present disclosure may provide one or more technical effects useful in the operation of an HVAC&R system. For example, the HVAC&R system may include a heat pump system configured to operate in a standby mode to reduce and / or block undesired fluid migration between a working fluid circuit (e.g., impeller cavity) and a motor cooling cavity of a motor configured to drive a compressor of the heat pump system. For example, the heat pump system may be configured to operate in the standby mode to block ingress of external fluid (e.g., air, noncondensable air, ambient air, motor cooling fluid) into the working fluid circuit the heat pump system. During operation in the standby mode, the working fluid may be heated by the HVAC&R system (e.g., compressor, heating system) to cause a pressure of the working fluid within the working fluid circuit to increase within the compressor. In this way, a portion of the working fluid may flow across a sealing system of the compressor and may block flow of external fluid into the compressor (e.g., into the impeller cavity of the compressor). As discussed above, embodiments of the present disclosure may include compressors having motors and / or open design motors (e.g., open compressors, non-hermetic compressor motors) configured to circulate air as a motor cooling fluid. The disclosed standby mode may enable more efficient operation of the compressor during varying stages or time periods, such as during suspended operation of the compressor, during operation of the compressor at a reduced capacity, and so forth. By blocking flow of external fluid into the compressor, the standby mode of the HVAC&R system may increase efficiency of the compressor and / or the heat pump system, such as by reducing down-time of the heat pump system associated with purging of non-condensable air within the heat pump system.

[0079] 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.

[0080] 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.

[0081] 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).

Claims

Claims1. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising: a working fluid circuit configured to circulate a working fluid therethrough; a compressor disposed along the working fluid circuit and configured to pressurize the working fluid, wherein the compressor comprises a housing comprising an impeller cavity configured to direct the working fluid therethrough and a first flow path fluidly coupled to the impeller cavity and to an ambient environment surrounding the compressor; and a control system configured to: operate the compressor in a standby mode, wherein a demand for conditioning by the HVAC&R system is absent in the standby mode; and in the standby mode, operate the HVAC&R system to increase a pressure of the working fluid to meet or exceed a threshold pressure value.

2. The HVAC&R system of claim 1, wherein the control system is configured to operate the compressor to increase the pressure of the working fluid in the standby mode.

3. The HVAC&R system of claim 1 or 2, wherein the threshold pressure value is based on a pressure of the ambient environment.

4. The HVAC&R system of claim 3, wherein the threshold pressure value is greater than the pressure of the ambient environment.

5. The HVAC&R system of one of claims 1 to 4, wherein the compressor comprises: an impeller disposed within the impeller cavity; and a motor configured to drive rotation of the impeller, wherein the motor comprises a motor cavity configured to direct a cooling fluid therethrough and a second flow path fluidly coupled to the motor cavity and to the ambient environment surrounding the compressor.

6. The HVAC&R system of claim 5, wherein the first flow path and the second flow path are fluidly coupled to one another within the housing.

7. The HVAC&R system of claim 6, wherein the housing comprises: a discharge port exposed to the ambient environment surrounding the compressor; and a third flow path extending from the first flow path and the second flow path to the discharge port, wherein the first flow path and the third flow path are configured to direct a portion of the working fluid from the impeller cavity to the ambient environment surrounding the compressor during operation in the standby mode.

8. The HVAC&R system of one of claims 5 to 7, wherein the motor is configured to receive a flow of air as the cooling fluid and to direct the flow air through the motor cavity and the second flow path.

9. The HVAC&R system of claim 7, wherein the compressor comprises a sealing system, and the sealing system comprises: a first labyrinth seal disposed along the first flow path; anda second labyrinth seal disposed along the second flow path.

10. The HVAC&R system of one of claims 1 to 9, comprising a heating system coupled to the working fluid circuit and communicatively coupled to the control system, wherein the control system is configured to operate the heating system increase the pressure of the working fluid to meet or exceed the threshold pressure value in the standby mode.

11. The HVAC&R system of claim 10, wherein the heating system comprises an electric heater.

12. The HVAC&R system of one of claims 1 to 11, comprising a sensor communicatively coupled to the control system and configured to detect an operating parameter of the working fluid, wherein the control system is configured to operate the HVAC&R system in the standby mode to increase the pressure of the working fluid in response to a determination that the operating parameter falls below a threshold value.

13. The HVAC&R system of one of claims 1 to 12, wherein the compressor is configured to circulate water through the working fluid circuit as the working fluid.

14. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising: a compressor comprising an impeller cavity and an impeller disposed within the impeller cavity, wherein the compressor is configured to pressurize a working fluid within the impeller cavity; a motor coupled to the compressor, wherein the motor is configured to drive rotation of the impeller to pressurize the working fluid, and the motor comprises a motor cavity configured to circulate a cooling fluid therethrough; a first flow path extending between the impeller cavity and an ambient environment surrounding the HVAC&R system; a second flow path extending between the motor cavity and the ambient environment surrounding the HVAC&R system; and a control system configured to:operate the HVAC&R system in a normal operating mode in response to a demand for heating or cooling; and operate the HVAC&R system in a standby mode in an absence of the demand for heating or cooling, wherein the control system is configured to operate the HVAC&R system to increase a pressure of the working fluid in the standby mode.

15. The HVAC&R system of claim 14, wherein the first flow path and the second flow path each extend at least partially through a housing of the compressor, the first flow path and the second flow path are fluidly coupled to one another within the housing, and the HVAC&R system comprises a labyrinth sealing system disposed along the first flow path, the second flow path, or both.

16. The HVAC&R system of claim 14 or 15, wherein the control system is configured to operate the motor to drive rotation of the impeller to increase the pressure of the working fluid in the standby mode.

17. The HVAC&R system of one of claims 14 to 16, comprising an electric heater coupled to the compressor, to a heat exchanger of the HVAC&R system, to a working fluid circuit of the HVAC&R system, or a combination thereof, wherein the control system is configured to operate the electric heater to increase the pressure of the working fluid in the standby mode.

18. The HVAC&R system of one of claims 14 to 17, wherein the control system is configured to operate the HVAC&R system to increase the pressure of the working fluid to meet or exceed a threshold pressure value in the standby mode, wherein the threshold pressure value is based on a pressure of the ambient environment surrounding the HVAC&R system, a pressure of the cooling fluid, or both.

19. A control system of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, wherein the control system is configured to:determine that a heating or cooling demand of the HVAC&R system is absent; operate the HVAC&R system in a standby mode based on the determination that the heating or cooling demand of the HVAC&R system is absent; receive data indicative of a detected parameter value of a working fluid of the HVAC&R system in the standby mode; determine that the detected parameter value is below a threshold value in the standby mode, wherein the threshold value is based on a pressure of an ambient environment surrounding the HVAC&R system; and operate the HVAC&R system in the standby mode to increase the detected parameter value of the working fluid in response to the determination that the detected parameter value is below the threshold value.

20. The control system of claim 18, wherein the detected parameter value is a detected temperature value of the working fluid or a detected pressure value of the working fluid, and the control system is configured to operate a compressor of the HVAC&R system to increase the detected parameter value of the working fluid in the standby mode, activate a heating system of the HVAC&R system to increase the detected parameter value of the working fluid in the standby mode, or both.

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