System and method for controlling operation of a cooler

Abstract

A heating, ventilation, air conditioning and refrigeration (HVACamp; in one embodiment, a system (10) includes a vapor compression system (100) having a vapor compression circuit (102, 104, 106) including a compressor system (108, 126, 144) configured to direct a working fluid through the vapor compression circuit (102, 104, 106) to provide a heat exchange relationship between the working fluid and a cooling fluid, a conditioning fluid, or both. The HVAC system (10) includes a controller (200) having a memory (206) and processing circuitry (204), where the memory (206) includes instructions that, when executed, cause the processing circuitry (204) to receive a signal to initiate operation of the vapor compression system (100), receive sensor data indicative of an operating condition of the vapor compression system (100), and transmit the sensor data to the memory (206). An expected lift of the compressor system (108, 126, 144) is determined based on the operating condition of the vapor compression system, the expected lift of the compressor system (108, 126, 144) is compared to a threshold value, and operation of the vapor compression system (100) is controlled based on the comparison of the expected lift to the threshold value.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of U.S. Provisional Application No. 63 / 352,157, filed on June 14, 2022, entitled “SYSTEMS AND METHODS FOR CONTROLLING OPERATION OF A CHILLER,” which is incorporated herein by reference in its entirety for all purposes. Background Art

[0003] This section is intended to introduce the reader to various aspects of the art, which may be related to various aspects of the present disclosure described below. This discussion is considered to be helpful in providing the reader with background information to facilitate a better understanding of various aspects of the present disclosure. Therefore, it should be understood that these statements will be interpreted from this perspective, rather than as admissions of prior art.

[0004] Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems may utilize a working fluid (e.g., a refrigerant) that changes phase between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures within components of the HVAC&R system (e.g., a vapor compression system). The HVAC&R system may place the working fluid in a heat exchange relationship with a conditioning fluid (e.g., water) to heat and / or cool the conditioning fluid, and may then deliver the conditioning fluid to various destinations for use. For example, the HVAC&R system may include a heat pump system (e.g., a heat pump vapor compression system) that includes one or more heat exchangers that are each configured to receive a working fluid and a respective additional fluid and place the working fluid in a heat exchange relationship with the additional fluid. The heat pump system may include one or more compressors that are configured to pressurize the working fluid and circulate the working fluid through a working fluid circuit (e.g., a vapor compression circuit). It is now recognized that improved systems and methods for controlling and / or initiating operation of an HVAC&R system are desired. Summary of the invention

[0005] The following describes a summary of certain embodiments disclosed herein. It should be understood that these aspects presented are only intended to provide the reader with a brief summary of these embodiments, and these aspects are not intended to limit the scope of the present disclosure. In fact, the present disclosure may encompass various aspects that may not be described below.

[0006] In one embodiment, a heating, ventilation, air conditioning and refrigeration (HVAC&R) system includes a vapor compression system having a vapor compression circuit including a compressor system configured to direct a working fluid through the vapor compression circuit to provide a heat exchange relationship between the working fluid and a cooling fluid, a conditioning fluid, or both. The HVAC system further includes a controller having a memory and a processing circuit system, wherein the memory includes instructions stored thereon that, when executed by the processing circuit system, cause the processing circuit system to receive a signal to initiate operation of the vapor compression system, receive sensor data indicative of an operating condition of the vapor compression system, determine an expected lift of the compressor system based on the operating condition of the vapor compression system, compare the expected lift of the compressor system to a threshold value, and control operation of the vapor compression system based on the comparison of the expected lift to the threshold value.

[0007] In another embodiment, a heating, ventilation, air conditioning and refrigeration (HVAC&R) system includes a vapor compression system having a plurality of vapor compression circuits, wherein each vapor compression circuit includes a compressor configured to direct a working fluid through the vapor compression circuit to establish a heat exchange relationship between the working fluid and a conditioning fluid. The HVAC&R system further includes a controller including a memory and a processing circuit system, wherein the memory includes instructions stored thereon, which when executed by the processing circuit system cause the processing circuit system to receive a signal to initiate operation of the vapor compression system, receive sensor data indicating an operating condition of the vapor compression system, and determine an expected lift of a corresponding compressor of each vapor compression circuit based on the operating condition of the vapor compression system. The instructions, when executed, further cause the processing circuit system to compare the expected lift with a threshold value, and control the operation of the vapor compression system based on the comparison of the expected lift with the threshold value.

[0008] In another embodiment, a tangible, non-transitory, computer-readable medium includes instructions executable by processing circuitry of a vapor compression system, the instructions, when executed by the processing circuitry, causing the processing circuitry to receive a signal to initiate operation of the vapor compression system; receive sensor data indicative of an operating condition of the vapor compression system; determine an expected lift for each of one or more compressors of the vapor compression system based on the operating condition of the vapor compression system; and determine a corresponding lower frequency limit for each of the one or more compressors based on the expected lift. The instructions, when executed, further cause the processing circuitry to compare the corresponding lower frequency limit for each of the one or more compressors with a threshold value, and control operation of the vapor compression system based on the comparison of the corresponding lower frequency limit for each of the one or more compressors with the threshold value. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Various aspects of the present disclosure may be better understood by reading the following detailed description and referring to the accompanying drawings, in which:

[0010] Figure 1 is a perspective view of an embodiment of a building utilizing a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system in a commercial environment according to an aspect of the present disclosure;

[0011] Figure 2 is a perspective view of an embodiment of a vapor compression system according to an aspect of the present disclosure;

[0012] Figure 3 is a schematic diagram of an embodiment of a vapor compression system according to an aspect of the present disclosure;

[0013] Figure 4 is a schematic diagram of an embodiment of a vapor compression system according to an aspect of the present disclosure;

[0014] Figure 5 is a schematic diagram of an embodiment of a vapor compression system having three vapor compression circuits according to an aspect of the present disclosure;

[0015] Figure 6 is a schematic diagram of an embodiment of an HVAC&R system including a heat pump system in an open-loop configuration according to an aspect of the present disclosure;

[0016] Figure 7 is a flow chart of an embodiment of a method for controlling startup of a vapor compression system according to an aspect of the present disclosure; and

[0017] Figure 8 is a flow chart of an embodiment of a method for controlling startup of a vapor compression system according to an aspect of the present disclosure. DETAILED DESCRIPTION

[0018] One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the technology disclosed in the present invention. In addition, in order to provide a concise description of these embodiments, all features of the actual implementation scheme may not be described in the specification. It should be understood that in the development of any such actual implementation scheme, as in any engineering or design project, a large number of implementation scheme-specific decisions may be made to achieve the developer's specific goals, such as meeting system-related and business-related constraints, which goals may vary from implementation scheme to implementation scheme. In addition, it should be understood that such development work may be complex and time-consuming, but it is still a routine work in design, production and manufacturing for ordinary technicians who benefit from the present disclosure.

[0019] 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 described. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements in addition to 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 described features.

[0020] As used herein, the terms "approximately," "substantially," "substantially," and the like are intended to convey that the value of the characteristic being described is likely to be within a relatively small range of the value of the characteristic, as understood by one of ordinary skill in the art. For example, when a characteristic value is described as being "approximately" equal to (or, for example, "substantially similar to") a given value, this is intended to convey that the characteristic value is likely to be within + / -5%, within + / -4%, within + / -3%, within + / -2%, within + / -1%, or even closer to the given value. Similarly, when a given feature is described as being "substantially parallel," "substantially perpendicular" to another feature, etc., this is intended to convey that the given feature is within + / -5%, within + / -4%, within + / -3%, within + / -2%, within + / -1%, or even closer to having the described property, such as being parallel to another feature, perpendicular to another feature, etc. Mathematical terms, such as "parallel" and "perpendicular," should not be strictly interpreted in a strict mathematical sense, but rather should be interpreted in the manner in which one of ordinary skill in the art would interpret such terms. For example, one of ordinary skill in the art will understand that two lines that are substantially parallel to each other are largely parallel, but may have slight deviations from being completely parallel.

[0021] As briefly discussed above, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system can be used to thermally condition a space within a building, residence, or other suitable structure. For example, an HVAC&R system can include a vapor compression system (e.g., a chiller system, a heat pump system) that transfers thermal energy between a working fluid (e.g., a refrigerant, a heat transfer fluid) and a fluid to be conditioned (e.g., air, water, or brine). The vapor compression system can include one or more vapor compression circuits (e.g., a heat pump), each of which can include a condenser and an evaporator fluidically coupled to each other by one or more conduits (e.g., a vapor compression circuit, a refrigeration circuit). In certain embodiments, the vapor compression system can be an open loop system, as described in more detail below. Further, each vapor compression circuit can include a compressor configured to pressurize a working fluid and circulate the working fluid through the circuit, and thus can transfer thermal energy between the working fluid and the fluid to be conditioned through a condenser and / or an evaporator.

[0022] A compressor (e.g., a centrifugal compressor) can be designed for certain operating conditions, which can include one or more characteristics or parameters of a working fluid (e.g., a refrigerant). For example, a compressor can be designed and / or selected for implementation in an HVAC&R system based on a working fluid flow rate (e.g., flow rate), a working fluid temperature and pressure condition at a suction inlet of the compressor, and / or a working fluid temperature and pressure condition at a discharge outlet of the compressor. In some applications, an HVAC&R system can utilize multiple vapor compression circuits, each of which has a corresponding compressor configured to achieve a desired lift (e.g., pressure differential) of a working fluid directed through the corresponding vapor compression circuit. The lift or "head" of a compressor can be defined as the power or production rate of the compressor and can be expressed as the difference between the compressor discharge pressure and the compressor suction pressure. The operation of each compressor can be controlled to enable operation under various design conditions (e.g., parameters) and / or to avoid undesirable operation or operating conditions (e.g., compressor surge, compressor stall).

[0023] Some HVAC&R systems include various components that are configured to adjust compressor operation, such as compressor speed, compressor flow rate, etc. For example, the HVAC&R system may include a variable frequency drive (VFD) or variable speed drive (VSD) configured to adjust compressor speed; a flow reducing device (FRD) configured to adjust the flow of a working fluid through the compressor (e.g., a pre-rotation vane [PRV] system, inlet guide vanes, and / or a variable geometry diffuser [VGD]); and / or a hot gas bypass valve configured to enable the working fluid to bypass and / or recirculate through the compressor. Control of the VSD, PRV, VGD, hot gas bypass valve, etc. may be based on data or feedback indicative of one or more operating conditions of the HVAC&R system, such as temperature and pressure data of the working fluid at the suction inlet and / or discharge outlet of the compressor, temperature and / or pressure data of the working fluid at the evaporator and condenser, temperature and / or pressure data of the fluid to be conditioned, PRV and / or VGD position data, hot gas bypass valve position data, temperature and / or pressure data of another fluid (e.g., cooling fluid, conditioning fluid), etc. The data from the sensors may be used to determine whether the HVAC&R system is operating to adequately meet the load demands of the HVAC&R system (e.g., cooling demand, lift demand) and / or whether to adjust the operation of the one or more components (e.g., to achieve or maintain operation of the HVAC&R system at various design conditions to more ideally meet the load demands, etc.).

[0024] Conventional HVAC&R systems that employ vapor compression systems (e.g., heat pump systems) may begin operation of the HVAC&R system without fully considering the startup conditions of the HVAC&R system. In doing so, conventional systems may be prone to begin operation of the HVAC&R system and / or operate the HVAC&R system under operating conditions that are more likely to cause surge of the one or more compressors employed by the HVAC&R system, thereby increasing wear and degradation of components of the HVAC&R system and reducing the efficiency of the HVAC&R system. HVAC&R systems having multiple vapor compression circuits may be particularly susceptible to conditions associated with surge at startup. For example, multiple vapor compression circuits arranged in a series countercurrent arrangement may have a greater temperature difference (e.g., greater than 20 degrees, greater than 30 degrees) between a conditioning fluid (e.g., water) directed through an evaporator of the vapor compression system and a cooling fluid (e.g., water) directed through a condenser of the vapor compression system. Therefore, embodiments of the present invention relate to systems and methods for evaluating startup conditions of a vapor compression system. The systems and methods may be used to enable or prevent startup of a vapor compression system based on an evaluation of various operating parameters and / or conditions of the vapor compression system at startup. In this manner, the present technology can be used to avoid a vapor compression system operating in a surge condition. The disclosed technology can be implemented in many types of HVAC&R systems, including vapor compression systems having multiple vapor compression circuits (e.g., arranged in a series countercurrent arrangement), vapor compression systems having a single vapor compression circuit, vapor compression systems having an open loop cycle associated with a customer process, and the like.

[0025] Turning now to the accompanying drawings, Figure 11 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 environment. The HVAC&R system 10 may include a vapor compression system 14 (e.g., a chiller) that supplies a cooling liquid that can be used to cool the building 12. The HVAC&R system 10 may also include a boiler 16 for supplying warm liquid to heat the building 12 and an air distribution system that circulates air through the building 12. The air distribution system may 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 via ducts 24. Depending on the operating mode of the HVAC&R system 10, the heat exchanger in the air handler 22 may receive heated liquid from the boiler 16 or cooled liquid from the vapor compression system 14. The HVAC&R system 10 is shown with separate air handlers on each floor of the 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 floors.

[0026] Figure 2 and 3 An embodiment of a vapor compression system 14 is shown that can be used in the HVAC&R system 10. The vapor compression system 14 can circulate a working fluid through a circuit that begins with a compressor 32. The circuit can also include a condenser 34, an expansion valve or device 36, and a liquid cooler or evaporator 38. The vapor compression system 14 can further include a control panel 40 having an analog-to-digital (A / D) converter 42, a microprocessor 44, a non-volatile memory 46, and / or an interface board 48, and the control panel 40 can be configured to control various components of the vapor compression system 14, as discussed in more detail below.

[0027] Some examples of fluids that can be used as working fluids in the vapor compression system 14 are: hydrofluorocarbon (HFC) based refrigerants, such as R-410A, R-407, R-134a, hydrofluoroolefins (HFO); "natural" refrigerants, such as ammonia (NH3), R-717, carbon dioxide (CO2), R-744; or hydrocarbon-based refrigerants, water vapor, or any other suitable working fluid. In some embodiments, the vapor compression system 14 can be configured to efficiently utilize a working fluid having a standard boiling point of about 19 degrees Celsius (66 degrees Fahrenheit) at one atmosphere of pressure, which is also referred to as a low-pressure working fluid relative to a medium-pressure working fluid such as R-134a. As used herein, "standard boiling point" can refer to the boiling point temperature measured at one atmosphere of pressure.

[0028] In some embodiments, Figure 3As shown, the vapor compression system 14 may use one or more of the following: a pre-rotation vane system (PRV) 31, a variable geometry diffuser (VGD) 33, a hot gas bypass valve 35, a variable speed drive (VSD) 52, a motor 50, a compressor 32, a condenser 34, an expansion valve or device 36, and / or an evaporator 38. The PRV 31 and the VGD 33 are types of flow reduction devices (FRDs) for controlling the flow of a working fluid or heat transfer fluid (e.g., a refrigerant) through the compressor 32, thereby enabling the vapor compression system 14 to increase or decrease the capacity of the vapor compression system 14 based on load demand. Each of the PRV 31 and the VGD 33 may be coupled to an actuator, which may be communicatively coupled to a control panel 40. The control panel 40 may be configured to provide signals to the actuators of the PRV 31 and the VGD 33 to open the PRV 31 and / or the VGD 33, thereby increasing the flow of the heat transfer fluid (e.g., refrigerant) through the compressor 32, thereby increasing the operating (e.g., cooling) capacity of the vapor compression system 14. The control panel 40 may also provide signals to the actuators to close the PRV 31 and / or the VGD 33, thereby reducing the capacity of the vapor compression system 14. The hot gas bypass valve 35 may be configured to direct the heat transfer fluid vapor from the discharge outlet of the compressor 32 to the suction inlet of the compressor 32, as discussed in more detail below.

[0029] The motor 50 can drive the compressor 32 and can be powered by a variable speed drive (VSD) 52. The VSD 52 receives AC power having a specific fixed line voltage and a fixed line frequency from an alternating current (AC) power source and provides power having a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 can be powered directly by an AC or direct current (DC) power source. The motor 50 can include any type of motor that can be powered by a VSD or directly by an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

[0030] The compressor 32 compresses the working fluid vapor and delivers the vapor to the condenser 34 through the exhaust passage. In some embodiments, the compressor 32 may be a centrifugal compressor. The working fluid vapor delivered to the condenser 34 by the compressor 32 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34. Due to the heat transfer with the cooling fluid, the working fluid vapor may condense into a working fluid liquid in the condenser 34. The liquid working fluid from the condenser 34 may flow to the evaporator 38 through the expansion device 36. Figure 3 In the illustrated embodiment, the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56 that supplies cooling fluid to the condenser 34 .

[0031] The liquid working fluid delivered to the evaporator 38 may absorb heat from a conditioning fluid (e.g., water), which may or may not be the same cooling fluid used in the condenser 34. That is, the liquid working fluid in the evaporator 38 forms a heat exchange relationship with the conditioning fluid to cool the temperature of the conditioning fluid in the evaporator 38. Thus, the liquid working fluid in the evaporator 38 may undergo a phase change due to the heat exchange relationship from the liquid working fluid to the working fluid vapor. Figure 3 As shown in the illustrated embodiment, 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. A conditioning fluid (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) for the evaporator 38 enters the evaporator 38 through the return line 60R and exits the evaporator 38 through the supply line 60S. The evaporator 38 may reduce the temperature of the conditioning fluid in the tube bundle 58 by heat transfer with the working fluid. The tube bundle 58 in the evaporator 38 may 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 through the suction line to complete the cycle.

[0032] Figure 4 is a schematic diagram of vapor compression system 14 having an intermediate loop 64 coupled between condenser 34 and expansion device 36. Intermediate loop 64 may have an inlet line 68 directly fluidly connected to condenser 34. In other embodiments, inlet line 68 may be indirectly fluidly coupled to condenser 34. Figure 4 As shown in the illustrated embodiment, 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" Figure 4 In the illustrated embodiment, the intermediate vessel 70 is used as a flash tank, and the first expansion device 66 is configured to reduce 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 evaporate, and thus the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66.

[0033] In addition, the intermediate container 70 can provide further expansion of the liquid working fluid due to the pressure drop experienced by the liquid working fluid when entering the intermediate container 70 (e.g., due to the rapid increase in volume experienced when entering the intermediate container 70). The vapor in the intermediate container 70 can be drawn by the compressor 32 through the suction line 74 of the compressor 32. In other embodiments, the vapor in the intermediate container 70 can be drawn into an intermediate stage (e.g., not a suction stage) of the compressor 32. Due to the expansion in the expansion device 66 and / or the intermediate container 70, the enthalpy of the liquid collected in the intermediate container 70 can be lower than the enthalpy of the liquid working fluid leaving the condenser 34. The liquid from the intermediate container 70 can then flow through the second expansion device 36 in the pipeline 72 to the evaporator 38.

[0034] It should be understood that any of the features described herein may be combined with the vapor compression system 14 or any other suitable HVAC&R system. For example, the present technology may be combined with any HVAC&R system having an economizer (such as the intermediate container 70) and a compressor (such as the compressor 32). The following discussion describes the present technology in combination with an embodiment of a vapor compression system 14 having multiple vapor compression circuits arranged in a series counter-flow arrangement. However, it should be understood that the systems and methods described herein may be combined with other embodiments of the vapor compression system 14 and the HVAC&R system 10, including vapor compression systems 14 having one vapor compression circuit and / or having multiple vapor compression circuits arranged in other configurations.

[0035] Considering the foregoing, Figure 5 is a schematic diagram of an embodiment of a vapor compression system 100 (e.g., an HVAC&R system) having multiple vapor compression circuits (e.g., heat pumps). The multiple vapor compression circuits can be arranged in series with respect to the flow of a conditioning fluid and / or a cooling fluid directed through the respective components of the multiple vapor compression circuits. For example, according to aspects of the present disclosure, the vapor compression system 100 can include a first vapor compression circuit 102, a second vapor compression circuit 104, and a third vapor compression circuit 106. It should be understood that the vapor compression system 100 and / or its components can be implemented with any of the systems described above in accordance with the present technology. For example, the vapor compression system 100 can correspond to Figure 3 A vapor compression system 14.

[0036] In the illustrated embodiment, each vapor compression circuit 102, 104, 106 of the vapor compression system 100 is configured to direct a respective working fluid (e.g., refrigerant) from a respective evaporator through a respective compressor, through a respective condenser, and then back to the evaporator to circulate the working fluid through the respective vapor compression circuit. Additionally, the vapor compression circuits 102, 104, 106 are arranged in series countercurrent with respect to the flow of a cooling fluid and a conditioning fluid (e.g., a fluid to be conditioned, another cooling fluid) directed through the vapor compression system 100 (e.g., through each of the vapor compression circuits 102, 104, 106). For example, a conditioning fluid (e.g., water, air) may flow sequentially (e.g., in series) through the evaporators of the vapor compression circuits 102, 104, 106 to transfer heat to the working fluid directed through each vapor compression circuit 102, 104, 106, thereby cooling the conditioning fluid (e.g., in a cooling mode of the vapor compression system 100). In some embodiments, the evaporators of the vapor compression circuits 102, 104, 106 can each be configured to adjust the temperature of the conditioning fluid by five to ten degrees (e.g., degrees Celsius). In such embodiments, the temperature of the conditioning fluid can be reduced by approximately fifteen to thirty degrees when the conditioning fluid is directed through the vapor compression system 100 (e.g., through the vapor compression circuits 102, 104, 106). Similarly, a cooling fluid (e.g., water, air) can flow sequentially (e.g., in series) through the condensers of the vapor compression circuits 102, 104, 106. However, as shown in the illustrated embodiment, the cooling fluid can flow through the condensers of the vapor compression circuits 102, 104, 106 in a sequential order that is opposite to the corresponding sequential order of the evaporators through which the conditioning fluid flows. In this way, the vapor compression circuits 102, 104, 106 can be arranged in a series countercurrent arrangement. The respective working fluid of each vapor compression circuit may transfer heat to the cooling fluid as the cooling fluid passes through each of the condensers, thereby cooling the respective working fluid within each vapor compression circuit before directing the respective working fluid back to the respective evaporator.

[0037] The first vapor compression circuit 102 may include a compressor 108 (e.g., a first compressor, a first compressor system), a condenser 110 (e.g., a first condenser), an evaporator 112 (e.g., a first evaporator), an expansion valve 114 (e.g., a first expansion valve), and a hot gas bypass valve 116 (e.g., a first hot gas bypass valve). The compressor 108 may also include a pre-rotation vane (PRV) 118 (e.g., a PRV system, a first PRV) and a variable geometry diffuser (VGD) 120 (e.g., a first VGD). In some embodiments, the first compressor 108 may include the PRV 118 or the VGD 120. As will be appreciated, the PRV 118 may be an adjustable guide vane disposed at or near the inlet (e.g., the suction side) of the compressor 108 and is configured to control and / or regulate the flow of the working fluid entering the compressor 108 (e.g., by causing swirl or movement of the working fluid). The VGD 120 may be configured to adjust the size of the diffuser passage clearance of the compressor 108 (e.g., downstream of the impeller of the first compressor 108) to adjust and / or control the flow of the working fluid through the first compressor 108. The operation of the PRV 118 and / or the VGD 120 may be adjusted to control the operation of the vapor compression system 100 (e.g., the first vapor compression circuit 102 based on the load demand or cooling load of the vapor compression system 100) and / or to avoid stall and / or surge in the first compressor 108.

[0038] The first vapor compression loop 102 also includes a motor 122 (e.g., a first motor) configured to drive the first compressor 108 to rotate and a variable speed drive (VSD) 124 configured to control the operation of the motor 122. As described above, the VSD 124 can convert alternating current (AC) power having a specific fixed line voltage and a fixed line frequency from an AC power source into power having a variable voltage and frequency to drive the motor 122. In this way, the VSD 124 can operate the motor 122 to drive the compressor 108 at different speeds (e.g., based on the load requirements of the vapor compression system 100) to enable more efficient operation of the vapor compression system 100. That is, based on the needs of the system, the speed of the compressor 108 can be increased or decreased to operate the compressor 108 at a frequency lower limit corresponding to the desired lift while avoiding surge conditions. The first compression loop 102 can also include a hot gas bypass valve 116. In the illustrated embodiment, the hot gas bypass valve 116 is configured to direct the compressed working fluid from the discharge outlet of the first compressor 108 to the suction inlet of the first compressor 108. However, in some embodiments, the hot gas bypass valve 116 may be configured to direct the compressed working fluid from the discharge outlet of the first compressor 108 to a location downstream of the expansion valve 114 and upstream of the evaporator 112 (e.g., along the first vapor compression circuit 102). Further, the PRV 118, VGD 120, hot gas bypass valve 116, and / or VSD 124 may be operated or controlled to adjust the flow rate and / or pressure difference (e.g., lift, head) of the working fluid directed through the first compressor 108 (e.g., based on the load or cooling demand of the vapor compression system 100).

[0039] The vapor compression system 100 also includes various components associated with the second vapor compression circuit 104. For example, the second vapor compression circuit 104 may include a compressor 126 (e.g., a second compressor, a second compressor system), a condenser 128 (e.g., a second condenser), an evaporator 130 (e.g., a second evaporator), an expansion valve 132 (e.g., a second expansion valve), and a hot gas bypass valve 134 (e.g., a second hot gas bypass valve). The compressor 126 may also include a pre-rotation vane (PRV) 136 (e.g., a second PRV system, a second PRV) and a variable geometry diffuser (VGD) 138 (e.g., a second VGD). In some embodiments, the second compressor 126 may include the PRV 136 or the VGD 138. Similar to the PRV 118 of the first vapor compression circuit 102, the PRV 136 may be an adjustable guide vane disposed at or near the inlet (e.g., suction side) of the compressor 126 and configured to control and / or regulate the flow of the working fluid entering the compressor 126 (e.g., by causing swirl or motion of the working fluid). The VGD 138 may be configured to adjust the size of the diffuser passage gap of the compressor 126 (e.g., downstream of the impeller of the second compressor 126) to regulate and / or control the flow of the working fluid through the second compressor 126. The operation of the PRV 136 and / or the VGD 138 may be adjusted to control the operation of the vapor compression system 100 (e.g., the second vapor compression circuit 104) and / or to avoid stall and / or surge in the second compressor 126.

[0040] The second vapor compression loop 104 also includes a motor 140 (e.g., a second motor) configured to drive the second compressor 126 to rotate and a variable speed drive (VSD) 142 configured to control the operation of the motor 140. As described above, the VSD 142 can convert alternating current (AC) power having a specific fixed line voltage and a fixed line frequency from an AC power source into power having a variable voltage and frequency to drive the motor 140. In this way, the VSD 142 can operate the motor 140 to drive the compressor 126 at different speeds (e.g., based on the load requirements of the vapor compression system 100) to enable more efficient operation of the vapor compression system 100. That is, based on the needs of the system, the speed of the second compressor 126 can be increased or decreased to operate the compressor 126 at a frequency lower limit corresponding to the desired lift while avoiding surge conditions. The second vapor compression loop 104 can also include a hot gas bypass valve 134. In the illustrated embodiment, the hot gas bypass valve 134 is configured to direct the compressed working fluid from the discharge outlet of the second compressor 126 to the suction inlet of the second compressor 126. However, in some embodiments, the hot gas bypass valve 134 may be configured to direct the compressed working fluid from the discharge outlet of the second compressor 126 to a location downstream of the expansion valve 132 and upstream of the evaporator 130 (e.g., along the second vapor compression circuit 104). Further, the PRV 136, VGD 138, hot gas bypass valve 134, and / or VSD 142 may be operated or controlled to adjust the flow rate and / or pressure difference (e.g., lift, head) of the working fluid directed through the second compressor 126 (e.g., based on the load or cooling demand of the vapor compression system 100).

[0041] The third vapor compression circuit 106 may include a compressor 144 (e.g., a third compressor, a third compressor system), a condenser 146 (e.g., a third condenser), an evaporator 148 (e.g., a third evaporator), an expansion valve 150 (e.g., a third expansion valve), and a hot gas bypass valve 152 (e.g., a third hot gas bypass valve). The compressor 144 may also include a pre-rotation vane (PRV) 154 (e.g., a third PRV system, a third PRV) and a variable geometry diffuser (VGD) 156 (e.g., a third VGD). In some embodiments, the third compressor 144 may include the PRV 154 or the VGD 156. Similar to the PRV 118 of the first vapor compression circuit 102, the PRV 154 may be an adjustable guide vane disposed at or near the inlet (e.g., the suction side) of the compressor 144 and configured to control and / or regulate the flow of the working fluid entering the compressor 144 (e.g., by causing swirl or movement of the working fluid). VGD 156 may be configured to adjust the size of a diffuser passage gap of compressor 144 (e.g., downstream of an impeller of third compressor 144) to adjust and / or control the flow of the working fluid through third compressor 144. Operation of PRV 154 and / or VGD 156 may be adjusted to control operation of vapor compression system 100 (e.g., second vapor compression circuit 104) and / or to avoid stall and / or surge in third compressor 144.

[0042] The third compression circuit 106 also includes a motor 158 (e.g., a third motor) configured to drive the third compressor 144 to rotate and a variable speed drive (VSD) 160 configured to control the operation of the motor 158. As described above, the VSD 160 can convert alternating current (AC) power having a specific fixed line voltage and a fixed line frequency from an AC power source into power having a variable voltage and frequency to drive the motor 158. In this way, the VSD 160 can operate the motor 158 to drive the compressor 144 at different speeds (e.g., based on the load requirements of the vapor compression system 100) to enable more efficient operation of the vapor compression system 100. That is, based on the needs of the system, the speed of the third compressor 144 can be increased or decreased to operate the compressor 144 at a frequency lower limit corresponding to the desired lift while avoiding surge conditions. The third compression circuit 106 can also include a hot gas bypass valve 152. In the illustrated embodiment, the hot gas bypass valve 152 is configured to direct the compressed working fluid from the discharge outlet of the third compressor 144 to the suction inlet of the third compressor 144. However, in some embodiments, the hot gas bypass valve 152 may be configured to direct the compressed working fluid from the discharge outlet of the third compressor 144 to a location downstream of the expansion valve 150 and upstream of the evaporator 148 (e.g., along the third vapor compression circuit 106). Further, as discussed in more detail below, the PRV 154, the VGD 156, the hot gas bypass valve 152, and / or the VSD 160 may be operated or controlled to adjust the flow rate and / or pressure differential (e.g., lift, head) of the working fluid directed through the third compressor 144 (e.g., based on the load or cooling demand of the vapor compression system 100).

[0043] It should be noted that the techniques discussed herein can be implemented in any suitable embodiment of a vapor compression system 100 having any number of vapor compression circuits (e.g., 1, 2, 4, 5, or more). For example, the present techniques can be used in embodiments of the vapor compression system 100 including chiller systems, heat pump systems, and / or other types of HVAC&R systems. Further, in some embodiments, the techniques discussed herein can be employed by a vapor compression system having fewer or more components than the vapor compression system 100 described above. For example, although each of the vapor compression circuits 102, 104, 106 is described above as having a corresponding VSD configured to control the operation of a corresponding motor driving a compressor within the corresponding vapor compression circuit, in some embodiments, one of the vapor compression circuits 102, 104, 106 can be associated with a corresponding VSD, and the other vapor compression circuits 102, 104, 106 can include a fixed speed motor configured to operate at a fixed speed to drive a corresponding compressor. Similarly, in some embodiments, one or more of the vapor compression circuits 102, 104, 106 may not include one or more of the above-mentioned PRV, VGD, or hot gas bypass valve. Still further, in certain embodiments, one or more of the vapor compression circuits 102, 104, 106 may be omitted. For example, the technology disclosed in the present invention may be used in a vapor compression circuit that may include one or more compressors, one or more evaporators, and one or more condensers.

[0044] Each vapor compression circuit 102, 104, 106 of the vapor compression system 100 directs a corresponding working fluid (e.g., refrigerant) from a corresponding compressor 108, 126, 144 to a corresponding condenser 110, 128, 146 within each vapor compression circuit 102, 104, and 106. Each condenser 110, 128, 146 is configured to transfer heat (e.g., thermal energy) from the working fluid to a cooling fluid (e.g., water, air) in order to cool and / or condense the working fluid within each vapor compression circuit 102, 104, 106. Thereafter, the working fluid within each vapor compression circuit 102, 104, 106 is directed through a corresponding expansion valve 114, 132, 150 and to a corresponding evaporator 112, 130, 148 of each vapor compression circuit 102, 104, and 106. The evaporators 112, 130, 148 can be fluidly coupled in series with respect to the flow of the conditioning fluid directed through the evaporators 112, 130, 148. The conditioning fluid (e.g., water) can also be directed to a load 172 (e.g., a cooling load) to provide cooling to the load 172. To this end, each evaporator 112, 130, 148 can enable heat (e.g., thermal energy) to be transferred from the conditioning fluid to the working fluid, thereby heating the working fluid within each evaporator 112, 130, 148 and cooling the conditioning fluid directed therethrough. For example, each evaporator 112, 130, 148 can place the working fluid in a heat exchange relationship with the conditioning fluid (e.g., water) that circulates through the load 172 to cool. In some embodiments, each evaporator 112, 130, 148 can be configured to reduce the temperature of the conditioning fluid by five to ten degrees (e.g., degrees Celsius). Thus, in some embodiments, the temperature of the conditioning fluid may be reduced by approximately fifteen to thirty degrees as the conditioning fluid is directed continuously through the evaporators 112, 130, 148 of the vapor compression system 100. It should be understood that embodiments of the present disclosure also include the vapor compression system 100 as a heat pump (e.g., a chiller heat pump) configured to operate to provide heating to the load 172. Thus, in some embodiments, the heat transfer within the condensers 110, 128, 146 and evaporators 112, 130, 148 discussed above may be reversed.

[0045] As described above, vapor compression circuits 102, 104, 106 are configured to be arranged in series countercurrent. Therefore, condensers 110, 128, 146 can be connected in series fluidly relative to the direction of the cooling fluid guided therethrough. Condensers 110, 128, 146 are also connected fluidically with cooling tower 170, which can be configured to discharge heat from the cooling fluid to another fluid stream (e.g., air stream). As shown in the embodiment shown, the cooling fluid from cooling tower 170 can be directed to the third condenser 146 of the third vapor compression circuit 106, so that the working fluid of the third vapor compression circuit 106 can transfer heat to the cooling fluid. Therefore, the cooling fluid can be directed to the second condenser 128 of the second vapor compression circuit 104, so that the working fluid of the second vapor compression circuit 104 can transfer heat to the cooling fluid. The cooling fluid may then be directed to the first condenser 110 of the first vapor compression loop 102, and heat may be transferred from the working fluid of the first vapor compression loop 102 to the cooling fluid before the cooling fluid is directed back to the cooling tower 170 to remove the heat absorbed from the working fluid of the vapor compression loops 102, 104, 106. The cooling fluid may then be directed back to the third condenser 146 to continue the cycle.

[0046] Similarly, the evaporators 112, 130, 148 can be fluidly coupled in series relative to the direction of the conditioning fluid directed therethrough. The evaporators 112, 130, 148 are also fluidly coupled to the load 172. Notably, the vapor compression system 100 is configured to direct the conditioning fluid through each of the evaporators 112, 130, 148 in a direction (e.g., sequential order) opposite to the flow direction (e.g., sequential order) of the cooling fluid directed from the cooling tower 170 through the condensers 110, 128, 146. For example, the conditioning fluid can first be directed from the load 172 to the first evaporator 112 of the first vapor compression circuit 102, whereby the working fluid within the first evaporator 112 can receive heat from the conditioning fluid to cool the conditioning fluid. Thereafter, the conditioning fluid can be directed to the second evaporator 130 of the second vapor compression circuit 104 to transfer heat to the working fluid in the second vapor compression circuit 104, thereby further cooling the conditioning fluid. The conditioning fluid may then be directed to the third evaporator 148 of the third vapor compression loop 106 to transfer heat to the working fluid within the third evaporator 148 before being directed back to the load 172 to provide cooling to the load 172. As described above, in some embodiments, the vapor compression system 100 may operate as a heat pump configured to provide heating to a building (e.g., the load 172). Additionally, it should be noted that Figure 5The vapor compression system 100 shown in the figure can be referred to as a closed-loop system, in which the working fluid is directed from the corresponding compressor to the corresponding condenser, to the corresponding evaporator, and back to the corresponding compressor in each vapor compression circuit 102, 104 and 106.

[0047] In certain embodiments, the HVAC&R system 100 may correspond to a heat pump system having an open loop cycle in communication with a customer process fluid. Figure 6 is a schematic diagram of an embodiment of an HVAC&R system 100 including a heat pump system 250 (e.g., a mechanical vapor compression system). In the illustrated embodiment, the heat pump system 250 is configured as an open (e.g., open loop) heat pump system 250. The open heat pump system 250 may include at least a portion of a vapor compression circuit 252 having a heat exchanger 254 (e.g., an evaporator 254), a first compressor 256, a second compressor 258, and an expansion valve 260. Similar to Figure 5 In the compressors 108, 126, 144 of the first compressor 256, the first compressor 256 may include a pre-rotation vane (PRV) 264 (e.g., a PRV system) and a variable geometry diffuser (VGD) 266. In some embodiments, the first compressor 256 may include a PRV 264 or a VGD 266. As will be appreciated, the PRV 264 may be an adjustable guide vane disposed at or near the inlet (e.g., the suction side) of the compressor 256 and configured to control and / or regulate the flow of a working fluid (e.g., steam) entering the compressor 256 (e.g., by causing swirl or movement of the working fluid). The VGD 266 may be configured to adjust the size of a diffuser passage gap of the compressor 256 (e.g., downstream of the impeller of the first compressor 256) to regulate and / or control the flow of the working fluid through the first compressor 256. Operation of PRV 264 and / or VGD 266 may be adjusted to control operation of heat pump system 250 (eg, vapor compression circuit 252 based on load demand or cooling load of heat pump system 250 ) and / or to avoid stall and / or surge in first compressor 256 .

[0048] The first compressor 256 is coupled to a motor 268 (e.g., a first motor) configured to drive the first compressor 256 to rotate and a variable speed drive (VSD) 270 configured to control the operation of the motor 268. As described above, the VSD 270 can convert alternating current (AC) power having a specific fixed line voltage and a fixed line frequency from an AC power source into power having a variable voltage and frequency to drive the motor 268. In this manner, the VSD 270 can operate the motor 268 to drive the compressor 256 at different speeds (e.g., based on the load demand of the heat pump system 250, the load demand of the customer process 262) to enable more efficient operation of the heat pump system 250. That is, based on the needs of the system, the speed of the compressor 256 can be increased or decreased to operate the compressor 256 at a frequency lower limit corresponding to the desired lift while avoiding surge conditions.

[0049] The second compressor 258 may also include a pre-rotation vane (PRV) 272 (e.g., a second PRV system) and a variable geometry diffuser (VGD) 274. In some embodiments, the second compressor 256 may include a PRV 272 or a VGD 274. Similar to the PRV 264 of the first compressor 256, the PRV 272 may be an adjustable guide vane disposed at or near the inlet (e.g., the suction side) of the compressor 258 and configured to control and / or regulate the flow of the working fluid entering the compressor 258 (e.g., by causing swirl or movement of the working fluid). The VGD 274 may be configured to adjust the size of the diffuser channel gap of the compressor 258 (e.g., downstream of the impeller of the second compressor 258) to regulate and / or control the flow of the working fluid through the second compressor 258. The operation of the PRV 272 and / or the VGD 274 may be adjusted to control the operation of the heat pump system 250 (e.g., the vapor compression loop 252) and / or to avoid stall and / or surge in the second compressor 258. The second compressor 258 is also coupled to a motor 276 (e.g., a second motor) configured to drive the second compressor 258 to rotate and a variable speed drive (VSD) 278 configured to control the operation of the motor 276. As described above, the VSD 278 may convert alternating current (AC) power having a specific fixed line voltage and a fixed line frequency from an AC power source into power having a variable voltage and frequency to drive the motor 276. In this manner, the VSD 278 may operate the motor 276 to drive the compressor 258 at different speeds (e.g., based on the load demand of the heat pump system 250, the load demand of the customer process 262) to enable more efficient operation of the heat pump system 250. That is, based on the demands of the system, the speed of the second compressor 258 may be increased or decreased to operate the compressor 258 at a lower frequency limit corresponding to the desired lift while avoiding surge conditions.

[0050] The open heat pump system 250 (e.g., vapor compression loop 252) is configured to circulate a working fluid (e.g., water, refrigerant, steam) to cool and / or heat one or more fluids and / or provide thermal energy to a customer process 262 (e.g., a client process). For example, the customer process 262 can receive a compressed working fluid (e.g., steam) from the first compressor 256 and the second compressor 258, and the heat provided by the compressed working fluid can be utilized by the customer process 262 (e.g., an industrial process, an HVAC&R process, a heating load, a cooling load, a district heating system, etc.) to meet the heating demand and / or thermal load (e.g., heating fluid) of the customer process 262, thereby cooling the working fluid. In turn, as the working fluid exchanges heat with the customer process 262, the working fluid may condense before returning to the vapor compression loop 252. In certain embodiments, the customer process 262 may also include an additional heat exchanger (e.g., a boiler) configured to provide additional fluids (e.g., steam, air, oil, process fluid) and / or thermal energy to the customer process 262. Thus, in certain embodiments, the condensed vapor returned to the vapor compression loop 252 may come from another heat exchanger of the customer process 262 rather than from the first compressor 256 and the second compressor 258, thereby forming an open loop cycle.

[0051] like Figure 6 As shown, the working fluid (e.g., condensed steam, liquid water) returned from the customer process 262 can be directed toward the expansion valve 260 before being directed to the evaporator 254 to exchange heat with the fluid (e.g., cooling fluid) 280 circulating through the evaporator 254. For example, the expansion valve 260 can reduce the pressure of the working fluid, thereby further reducing the temperature of the working fluid before the working fluid is directed through the evaporator 254. The cooled condensed working fluid can then exchange heat with the conditioning fluid 280 directed through the evaporator 254, thereby cooling the conditioning fluid 280. For example, the evaporator 254 can transfer heat (e.g., thermal energy) from the conditioning fluid 280 to the working fluid, thereby heating the working fluid within the evaporator 254 and cooling the conditioning fluid 280 directed therethrough. As the working fluid receives heat from the conditioning fluid 280, the working fluid can be converted into a working fluid vapor, which can be returned to the compressors 256, 258 for compression before being directed through the heat pump system 250 and toward the customer process 262. In certain embodiments, the heat pump system 250 may also include an isolation valve 282 configured to control the flow of compressed working fluid (eg, steam) toward the customer process 262 .

[0052] In certain embodiments, the heat pump system 250 can be configured to operate with a cascade system including an additional heat exchanger (e.g., a condenser). The cascade system can provide additional heat exchange capabilities, thereby enabling adjustment of operating parameters of the working fluid directed through the heat pump system 250. For example, in certain embodiments, the operation of the cascade system can be started before starting the operation of the heat pump system 250, thereby enabling the working fluid directed through the cascade system to increase to a threshold temperature before the heat pump system 250 starts operating. In this way, potential surge conditions can be avoided, thereby reducing wear and degradation of the heat pump system 250.

[0053] refer to Figure 5 and 6 , the components of the vapor compression system 100, the vapor compression loops 102, 104, 106, and / or the heat pump system 250 and the vapor compression loop 252 may be controlled by a controller 200 (e.g., a control system, an automated controller). In some embodiments, the controller 200 may be Figure 3 and 4 2. The embodiment of the control panel 40 of the vapor compression system 100 is shown in FIG. 2. For example, the controller 200 may include an interface 202 (e.g., a user interface, a display, an interface board), a processing circuit system 204 (e.g., one or more microprocessors), a memory 206, and an analog-to-digital (A / D) converter 208. For example, the memory 206 may include a volatile memory, such as a random access memory (RAM) and / or a non-volatile memory, such as a read-only memory (ROM), an optical drive, a hard drive, a solid-state drive, or any other non-transitory computer-readable medium storing instructions that, when executed (e.g., when executed by the processing circuit system 204), enable control of the operation of the vapor compression system 100. The processing circuit system 204 may be configured to execute such instructions stored on the memory 206. In some embodiments, the processing circuit system 204 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.

[0054] The controller 200 is configured to control the operation of the vapor compression system 100 and / or the heat pump system 250 (e.g., control the operation of one or more components of the vapor compression loops 102, 104, 106, control the operation of one or more components of the vapor compression loops 252) to enable improved operation of the vapor compression system 100 and the heat pump system 250. For example, the controller 200 may be configured to coordinate the operation of the compressors 108, 126, 144, 256, 258 of each of the vapor compression loops 102, 104, 106, 252 and other components of the vapor compression loops 102, 104, 106, 252 based on the operating conditions of the vapor compression system 100 or the heat pump system 250 and / or the load of the vapor compression system 100 or the heat pump system 250. To this end, the controller 200 can be configured to output control signals to control the operation of the PRVs 118, 136, 154, 264, 272 (e.g., corresponding positions), the operation of the VGDs 120, 138, 156, 266, 274 (e.g., corresponding positions), the operation of the hot gas bypass valves 116, 134, 152 (e.g., positions), the operation of the motors 122, 140, 158, 268, 276 and / or the operation of the VSDs 124, 142, 160, 270, 278 associated with each of the compressors 108, 126, 144, 256, 258, respectively. As described above, in some embodiments, the controller 200 can adjust the operation of one or more components of the vapor compression system 100 and / or the heat pump system 250 based on the operating conditions of the vapor compression system 100 or the heat pump system 250, the load of the vapor compression system 100 or the heat pump system 250 (e.g., the heat demand of the customer process 262), or other suitable data. According to the present technology, the controller 200 is also configured to enable or prevent the operation of the vapor compression system 100 or the heat pump system 250 during the expected startup of the vapor compression system 100 or the heat pump system 250 (e.g., after the vapor compression system 100 is not operating, after the heat pump system 250 is not operating). Specifically, the controller 200 is configured to enable or prevent the startup of the vapor compression system 100 or the heat pump system 250 based on the detected operating conditions of the vapor compression system 100 or the heat pump system 250. In this manner, controller 200 is configured to reduce or avoid operation of vapor compression system 100 or heat pump system 250 under surge conditions (eg, conditions that may cause one or more of compressors 108 , 126 , 144 , 256 , 258 to surge).

[0055] To this end, the controller 200 may be configured to control the operation of the vapor compression system 100 and / or the heat pump system 250 based on feedback received from one or more sensors 210 of the vapor compression system 100 or the heat pump system 250. The sensors 210 may be configured to detect one or more operating conditions (e.g., operating parameters) of the vapor compression system 100 or the heat pump system 250 and provide feedback indicative of the operating conditions to the controller 200. The sensors 210 may include any suitable sensor configured to detect operating parameters of the vapor compression system 100, the heat pump system 250, and / or the vapor compression circuits 102, 104, 106, 252, such as a pressure sensor, a temperature sensor, a position sensor, a voltage sensor, a current sensor, a flow rate sensor, a speed sensor, etc.

[0056] exist Figure 5 and 6 In the illustrated embodiment, one or more sensors 210 are disposed at the respective inlet (e.g., suction side) of each of the compressors 108, 126, 144, 256, 258, the respective outlet (e.g., discharge side) of each of the compressors 108, 126, 144, 256, 258, the respective inlet (e.g., working fluid outlet, regulating fluid outlet) of each of the condensers 110, 128, 146, the respective outlet (e.g., working fluid outlet, regulating fluid outlet) of each of the condensers 110, 128, 146, the respective inlet (e.g., working fluid outlet, cooling fluid outlet) of each of the evaporators 112, 130, 148, 254, and the respective outlet (e.g., working fluid outlet, cooling fluid outlet) of each of the evaporators 112, 130, 148, 254. In addition, one of the sensors 210 may be positioned proximal to the isolation valve 282 to detect the pressure of the working fluid directed toward the customer process 262. In certain embodiments, one or more sensors 210 may be positioned at an inlet of a heat exchanger of a cascade system associated with the heat pump system 250 and / or at an outlet of a heat exchanger of a cascade system associated with the heat pump system 250. However, other embodiments of the vapor compression system 100 or the heat pump system 250 may include sensors 210 positioned at additional or alternative locations along the vapor compression loops 102, 104, 106 within the vapor compression system 100, at additional or alternative locations along the vapor compression loop 252 of the heat pump system 250, or at other suitable locations.

[0057] The sensors 210 may be configured to collect (e.g., measure, detect) data related to the working fluid, the conditioning fluid circulated by the evaporators 112, 130, 148, the cooling fluid circulated by the condensers 110, 128, 146, the conditioning fluid 280 circulated by the evaporator 254, and / or the conditioning fluid circulated by the heat exchanger of the cascade system associated with the heat pump system 250. For example, one or more of the sensors 210 may detect the temperature, pressure, flow rate, or other operating parameter of the working fluid within each vapor compression circuit 102, 104, 106, 252, the conditioning fluid directed through each vapor compression circuit 102, 104, and 106, the cooling fluid directed through each vapor compression circuit 102, 104, 106, the conditioning fluid directed through the heat exchanger of the cascade system associated with the heat pump system 250, and / or the conditioning fluid 280 directed through the evaporator 254. Further, one or more sensors 210 may be associated with the PRV 118, 136, 154, 264, 272, the VGD 120, 138, 156, 266, 274, and / or the hot gas bypass valve 116, 134, 152. For example, the sensor 210 may be configured to detect and transmit data indicative of a position of the PRV 118, 136, 154, 264, 272, the VGD 120, 138, 156, 266, 274, and / or the hot gas bypass valve 116, 134, 152. The vapor compression system 100 and / or the heat pump system 250 may also include one or more sensors 210 associated with the motors 122, 140, 158, 268, 276 and the VSDs 124, 142, 160, 270, 278, and the sensors 210 may be configured to detect and transmit data indicative of respective operating parameters (e.g., current, voltage, frequency, speed, position, etc.) of the motors 122, 140, 158, 268, 276 and the VSDs 124, 142, 160, 270, 278. It should be noted that the vapor compression system 100 and / or the heat pump system 250 may include sensors such as the ones described above. Figure 5 and 6 Fewer or more sensors 210 than those shown, and additional or alternative sensors 210 may be configured to detect one or more operating parameters and transmit data indicative of the operating parameters to the controller 200 for controlling the operation of the vapor compression circuits 102, 104, 106, 252 and / or other components of the vapor compression system 100 or the heat pump system 250.

[0058] As discussed above, the PRV 118, 136, 154, 264, 272 and / or the VGD 120, 138, 156, 266, 274 may operate as a flow reducing device (FRD) configured to control or otherwise regulate the flow of a working fluid through a corresponding compressor (e.g., compressor 108, 126, 144, 256, 258). One or more of the PRV 118, 136, 154, 264, 272 and the VGD 120, 138, 156, 266, 274 may be coupled to a corresponding actuator, each of which may be communicatively coupled to the controller 200. The actuator may be configured to operate based on a control signal received from the controller 200. For example, the actuators may be operated to adjust the respective positions of the PRVs 118, 136, 154, 264, 272 and / or the VGDs 120, 138, 156, 266, 274. In some embodiments, the controller 200 may instruct the one or more actuators to adjust one or more of the PRVs 118, 136, 154, 264, 272 toward an open position and / or to adjust one or more of the VGDs 120, 138, 156, 266, 274 toward an open position. In this manner, the controller 200 may control the vapor compression system 100 and / or the heat pump system 250 to increase the flow of the working fluid directed through one or more of the vapor compression circuits 102, 104, 106, 252, thereby increasing the capacity (e.g., operating capacity) of the vapor compression system 100 or the heat pump system 250. Similarly, the controller 200 can instruct one or more actuators to adjust one or more of the PRVs 118, 136, 154, 264, 272 toward a closed position and / or adjust one or more of the VGDs 120, 138, 156, 266, 274 toward a closed position in order to reduce the flow of the working fluid directed through one or more of the vapor compression circuits 102, 104, 106, 252, thereby reducing the capacity of the vapor compression system 100 or the heat pump system 250.

[0059] As discussed in more detail below, the controller 200 may be configured to operate the vapor compression circuits 102, 104, 106, 252 and other components of the vapor compression system 100 or the heat pump system 250 to enable improved operation of the vapor compression system 100 or the heat pump system 250. For example, the controller 200 is configured to enable or prevent operation of the vapor compression circuits 102, 104, 106, 252 based on detected operating conditions of the vapor compression system 100 or the heat pump system 250. Specifically, the controller 200 is configured to analyze the detected operating conditions (e.g., startup conditions) of the vapor compression system 100 or the heat pump system 250 to determine whether operation of the vapor compression system 100 or the heat pump system 250 under the detected operating conditions may cause one or more of the compressors 108, 126, 144, 256, 258 to surge and / or stall. Based on a determination that the detected operating condition is associated with an unacceptable surge and / or stall potential, the controller 200 may prevent startup of the vapor compression system 100 or the heat pump system 250 (e.g., one or more of the vapor compression circuits 102, 104, 106, 252). Thus, utilizing the inventive techniques disclosed herein, the controller 200 may limit or prevent operation of the vapor compression system 100 or the heat pump system 250 during undesirable operating conditions.

[0060] As will be appreciated, the operation and performance of the compressor 108, 126, 144, 256, 258 may be represented and / or defined in terms of a head coefficient (Ω) and a flow coefficient (θ). The head coefficient generally indicates a pressure ratio or pressure difference between a discharge pressure and a suction pressure of the compressor 108, 126, 144, 256, 258, and the flow coefficient generally indicates a flow rate (e.g., mass flow rate) of a fluid directed through the compressor 108, 126, 144, 256, 258. During operation at a particular speed (e.g., rotational speed), the operating point of the compressor 108, 126, 144, 256, 258 may generally be represented by corresponding head coefficient values ​​and flow coefficient values ​​associated with the compressor 108, 126, 144, 256, 258 at the particular speed. In fact, at a particular operating speed, each compressor 108, 126, 144, 256, 258 can be configured to operate at a respective operating point, wherein each operating point is well defined by a particular corresponding head coefficient value and flow coefficient value. The respective corresponding head coefficient value and flow coefficient value associated with the compressor 108, 126, 144, 256, 258 can be based on the particular design characteristics of the compressor 108, 126, 144, 256, 258. In addition, the compressor operating point can be adjusted and / or achieved by adjusting the operation of the compressor 108, 126, 144, 256, 258. For example, the speed of the compressor 108, 126, 144, 256, 258 and / or the position of the PRV 118, 136, 154, 264, 272 and / or the VGD 120, 138, 156, 266, 274 may be adjusted to adjust and / or achieve a particular operating point (e.g., a corresponding head coefficient value and flow coefficient value) of the compressor 108, 126, 144, 256, 258. However, it is desirable to avoid operating the compressor 108, 126, 144, 256, 258 at certain operating values ​​of the head coefficient and / or flow coefficient to avoid undesirable operating conditions or events, such as surge.

[0061] According to the present technique, the controller 200 is configured to control the operation of the vapor compression circuit 102, 104, 106, 252 in a manner to avoid surge conditions and / or to avoid an unacceptable surge potential in one or more of the compressors 108, 126, 144, 256, 258. More specifically, according to the present technique, the controller 200 is configured to detect operating conditions of the vapor compression system 100 or the heat pump system 250 (e.g., temperature and / or pressure data of a conditioning and / or cooling fluid directed through the vapor compression circuit 102, 104, 106, 252, temperature and / or pressure data of a working fluid directed through the vapor compression circuit 102, 104, 106, 252), and limit the operation of one or more of the compressors 108, 126, 144, 256, 258 based on a determination that the detected operating conditions correspond to a surge condition or to an unacceptable surge potential. For example, the present technology may be utilized prior to starting the vapor compression system 100 or the heat pump system 250, and the start of operation of the vapor compression system 100 or the heat pump system 250 may be prevented based on a determination that the detected startup conditions may result in surge within the vapor compression system 100 or the heat pump system 250. Thus, compared to conventional systems, embodiments of the present invention enable improved operation of the vapor compression system 100 or the heat pump system 250 by limiting operation (e.g., startup) of the vapor compression system 100 or the heat pump system 250 during undesirable operating conditions (e.g., surge conditions), thereby limiting potential wear and degradation that may occur during surge conditions. In fact, as discussed in more detail below, the controller 200 may be configured to limit operation (e.g., startup) of the vapor compression system 100 or the heat pump system 250 until the startup operating conditions enable the vapor compression system 100 or the heat pump system 250 to operate without surge and / or without an unacceptable likelihood of surge.

[0062] Considering the foregoing, Figure 7A flow chart of an embodiment of a method 600 (e.g., a capacity control scheme, control logic) for controlling the operation (e.g., controlling startup) of a vapor compression system 100 and / or a heat pump system 250 is presented. That is, the method 600 can be used to coordinate (e.g., start and / or prevent) startup of the vapor compression system 100 and / or the heat pump system 250. For example, the controller 200 (e.g., a single controller, a control system, a processing circuit system 204) can be configured to implement and / or execute the method 600 to control various components of the vapor compression system 100 or the heat pump system 250. In other embodiments, the method 600 can be implemented by another controller (e.g., a dedicated controller for the vapor compression system 100, a dedicated controller for the heat pump system 250), more than one controller, or other suitable control system. It should also be noted that additional steps can be performed with respect to the method 600. In addition, certain steps of the depicted method 600 can be removed, modified, and / or performed in a different order.

[0063] As mentioned above, when detected startup conditions (e.g., startup operating conditions) of the vapor compression system 100 or the heat pump system 250 may cause one or more of the compressors 108, 126, 144, 256, 258 to surge, the method 600 may be implemented to limit and / or prevent startup of the vapor compression system 100 or the heat pump system 250. In some embodiments, the inlet and / or outlet temperatures (e.g., conditioning fluid temperatures) of the evaporators 112, 130, 148 and the inlet and / or outlet temperatures (e.g., cooling fluid temperatures) of the condensers 110, 128, 146 within each vapor compression circuit 102, 104, 106 may be monitored and evaluated (e.g., before starting the vapor compression system 100) to evaluate the startup operating conditions of the vapor compression system 100. Similarly, the inlet and / or outlet temperatures of the evaporator 254 and the inlet and / or outlet temperatures of the heat exchangers of the cascade system associated with the heat pump system 250 may be monitored and evaluated (e.g., before the heat pump system 250 is started) to evaluate the startup operating conditions of the heat pump system 250. For example, the inlet and / or outlet temperatures of the evaporators 112, 130, 148 and the inlet and / or outlet temperatures of the condensers 110, 128, 146 may represent the operating conditions of the vapor compression system 100 at startup, while the inlet and / or outlet temperatures of the evaporator 254 and the inlet and / or outlet temperatures of the heat exchangers of the cascade system associated with the heat pump system 250 may represent the operating conditions of the heat pump system 250 at startup. In some embodiments, the inlet and / or outlet temperature of the evaporator 112, 130, 148, 254 may be the temperature of the conditioning fluid conditioned by the evaporator 112, 130, 148, 254, and the inlet and / or outlet temperature of the condenser 110, 128, 146 or the heat exchanger of the cascade system may be the temperature of the cooling fluid directed through the condenser 110, 128, 146 or the heat exchanger. As will be appreciated, the inlet and / or outlet temperature of the evaporator 112, 130, 148, 254 and the inlet and / or outlet temperature of the condenser 110, 128, 146 or the heat exchanger may be measured or detected by one of the above-mentioned sensors 210.

[0064] As described above, in some embodiments, the controller 200 can be configured to operate the vapor compression system 100 or the heat pump system 250 based on temperature conditions. For example, the difference between the inlet and / or outlet temperature of the evaporator 112, 130, 148 and the inlet and / or outlet temperature of the condenser 110, 128, 146 can correspond to the expected lift of the corresponding vapor compression circuit 102, 104, 106. Similarly, the difference between the inlet and / or outlet temperature of the evaporator 254 and the inlet and / or outlet temperature of the heat exchanger of the cascade system associated with the heat pump system 250 can correspond to the expected lift of the heat pump system 250 (e.g., the expected lift of the vapor compression circuit 252). Thus, as described in more detail below, the inventive techniques discussed herein utilize the difference between the inlet and / or outlet temperatures of the evaporator 112, 130, 148, 254 and the inlet and / or outlet temperatures of the condenser 110, 128, 146 or the heat exchanger to coordinate the startup of the vapor compression system 100 or the heat pump system 250. It should be noted that at startup, the inlet temperature of the evaporator 112, 130, 148, 254 may be substantially similar (e.g., within 1%) to the outlet temperature of the evaporator 112, 130, 148, 254, and the inlet temperature of the condenser 110, 128, 146 or the heat exchanger of the cascade system may be substantially similar (e.g., within 1%) to the outlet temperature of the condenser 110, 128, 146 or the heat exchanger of the cascade system. Thus, in certain embodiments, the controller 200 may be configured to utilize the inlet or outlet temperature of the evaporators 112, 130, 148, 254 and the inlet or outlet temperature of the condensers 110, 128, 146 or a heat exchanger of a cascade system to perform the techniques discussed herein.

[0065] In addition, in some embodiments, the controller 200 can be configured to use a pressure value in combination with or in place of the temperature value obtained from the sensor 210. For example, in some embodiments, the inlet and / or outlet temperature of the condenser may not be reached (e.g., embodiments in which the heat pump system 250 is not associated with a cascade system, embodiments in which the sensor 210 associated with the inlet and / or outlet of the condenser 110, 128, 146 or the heat exchanger of the cascade system is not operable). Therefore, the controller 200 can be configured to determine the expected lift using the pressure values ​​at the suction inlet and discharge outlet of the compressor 108, 126, 144, 256, 258. That is, the pressure ratio between the suction inlet and the discharge outlet (e.g., the process side) of a particular compressor 108, 126, 144, 256, 258 can be used to determine the expected lift of the corresponding compressor. In some embodiments, the sensor 210 associated with the isolation valve 282 in the heat pump system 250 can be configured to collect data indicating the discharge pressure (e.g., the process side pressure) of the compressors 256, 258. Additionally, in certain embodiments, the controller 200 may utilize temperature values ​​(e.g., inlet and / or outlet temperatures of the evaporator 112, 130, 148, 254) to calculate a saturated discharge temperature of the evaporator 112, 130, 148, 254, which may be used to calculate an expected pressure at the suction inlet of the compressor 108, 126, 144, 256, 258. In turn, a pressure value on the discharge side (e.g., process side) of the compressor 108, 126, 144, 256, 258 may be compared to the expected pressure at the suction inlet of the compressor 108, 126, 144, 256, 258 to establish a pressure ratio between the suction inlet and the discharge outlet of the compressor 108, 126, 144, 256, 258. The pressure ratio may then be used to determine an expected lift of the compressor 108, 126, 144, 256, 258.

[0066] In the illustrated embodiment, the method 600 begins with the vapor compression system 100 or the heat pump system 250 (e.g., the controller 200) receiving a signal to initiate startup of the vapor compression system 100 or the heat pump system 250, as indicated by block 602. For example, the vapor compression system 100 or the heat pump system 250 may receive the signal based on user input, based on a change in ambient conditions, based on a call for regulation, and / or any other suitable input. During normal startup, in some cases, the controller 200 may be configured to begin operation of each of the vapor compression circuits 102, 104, 106, or the vapor compression circuit 252 at a reduced capacity to meet the load demand of the vapor compression system 100 or the heat pump system 250 while promoting more efficient operation. For example, the VSDs 124, 142, 160, 270, 278 associated with the compressors 108, 126, 144, 256, 258, respectively, may be configured to operate at a reduced speed (e.g., 10% of an upper speed limit), and the positions of the PRVs 118, 136, 154, 264, 272 and / or the VGDs 120, 138, 156, 266, 274 may be associated with a reduced flow rate through the compressors 108, 126, 144, 256, 258 (e.g., PRV open 10%, VGD open 10%). During operation, as load demand increases, the controller 200 can gradually increase the speed of the VSD 124, 142, 160, 270, 278 and / or adjust the position of the PRV 118, 136, 154, 264, 272 and / or VGD 120, 138, 156, 266, 274 toward an open position (e.g., a fully open position) to increase the capacity of the vapor compression system 100 or the heat pump system 250.

[0067] At block 604, the controller 200 may determine an expected lift for each of the vapor compression circuits 102, 104, 106, 252 based on the startup operating conditions of the vapor compression system 100 or the heat pump system 250. For example, the controller 200 may receive signals from the sensor 210 indicating the inlet and / or outlet temperatures of the evaporators 112, 130, 148, 254 and the inlet and / or outlet temperatures of the condensers 110, 128, 146 or a heat exchanger of a cascade system associated with the heat pump system 250. As described above, the difference between the inlet and / or outlet temperatures of the evaporators 112, 130, 148 and the inlet and / or outlet temperatures of the condensers 110, 128, 146 within each vapor compression circuit 102, 104, 106 may correspond to the lift (e.g., the required lift) that each compressor 108, 126, 144 is expected to achieve based on the conditioning fluid and cooling fluid temperatures. Similarly, the difference between the inlet and / or outlet temperature of the evaporator 254 and the inlet and / or outlet temperature of the heat exchanger of the cascade system associated with the heat pump system 250 can correspond to the lift (e.g., required lift) that the compressors 256, 258 are expected to achieve based on the conditioning fluid and cooling fluid temperatures. In addition, as described above, the pressure value between the suction inlet and the discharge outlet of the compressors 108, 126, 144, 256, 258 can be used in combination with or in place of the temperature value to determine the expected lift.

[0068] Based on the operating conditions before the vapor compression system 100 or the heat pump system 250 is started, the controller 200 can determine that the expected lift at the start of one or more of the compressors 108, 126, 144, 256, 258 may cause the compressors 108, 126, 144, 256, 258 to experience a surge condition. For example, at box 606, the controller 200 can compare the expected lift (e.g., the difference between the inlet and / or outlet temperature of the evaporator and the inlet and / or outlet temperature of the condenser in the corresponding vapor compression circuit) with a threshold value (e.g., an upper limit of the lift). As described above, at startup, each of the vapor compression circuits 102, 104, 106, 252 can be configured to operate at a reduced capacity. Thus, the threshold value may correspond to an upper limit of lift that each compressor 108, 126, 144, 256, 258 can achieve when operating at reduced capacity at startup (e.g., where the VSD is operating at 10% of the upper frequency limit and the position of the PRV and / or VGD is open 10%) without experiencing a surge condition. In other words, the threshold value may be based on an expected or desired position of the PRV 118, 136, 154, 264, 272 and / or the VGD 120, 138, 156, 266, 274 and / or an expected or desired speed of the VSD 124, 142, 160, 270, 278. In some embodiments, each of the compressors 108, 126, 144, 256, 258 may be associated with a different threshold value based on the physical and / or structural characteristics (e.g., manufacturing specifications) of the respective compressors 108, 126, 144, 256, 258 and / or the location of the vapor compression circuits 102, 104, 106, 252 relative to each other. Further, it should be noted that the threshold value may be selected from a plurality of threshold values ​​empirically determined based on various data (e.g., empirical data), including but not limited to the values ​​of any of the parameters discussed above (e.g., cooling fluid temperature, conditioning fluid temperature). The threshold value may be selected based on a desired safety factor and / or an acceptable surge probability.

[0069] Based on determining (e.g., by controller 200) that the expected lift of one or more of compressors 108, 126, 144, 256, 258 does not exceed (e.g., is equal to or less than) a corresponding threshold (e.g., an upper lift limit) associated with compressor 108, 126, 144, 256, 258, method 600 can continue to box 608, and controller 200 can begin operation of vapor compression system 100 or heat pump system 250 (e.g., vapor compression circuit 102, 104, 106 with compressor 108, 126, 144 whose expected lift does not exceed the threshold, vapor compression circuit 252 with compressor 256, 258 whose expected lift does not exceed the threshold).

[0070] Based on a determination (e.g., by controller 200) that the expected lift of one of compressors 108, 126, 144, 256, 258 does exceed a corresponding threshold associated with compressor 108, 126, 144, 256, 258, method 600 may continue to box 610, and controller 200 may prevent operation of vapor compression system 100 or heat pump system (e.g., vapor compression circuit 102, 104, 106 having compressor 108, 126, 144 whose expected lift exceeds the threshold, vapor compression circuit 252 having compressor 256, 258 whose expected lift exceeds the threshold).

[0071] Additionally, based on determining that the expected lift of the compressor 108, 126, 144, 256, 258 exceeds the threshold, at block 612, the controller 200 may output (e.g., send) a notification to the user indicating that one or more of the compressors 108, 126, 144, 256, 258 of the vapor compression system 100 or the heat pump system 250 are susceptible to surge if the corresponding compressor 108, 126, 144, 256, 258 and / or the vapor compression system 100 or the heat pump system 250 are started under the existing conditions. In some embodiments, the notification may be displayed on the interface 202 of the controller 200 and may include an alarm or warning message notifying the user that there is a potential for surge if operation of the vapor compression system 100 or the heat pump system 250 is started. The notification may additionally or alternatively be sent to a computing device associated with the user to inform the user of the potential for surge. In some embodiments, the notification may include a suggestion that the expected lift of one or more of the compressors 108, 126, 144, 256, 258 can be reduced. For example, the suggestion may include a suggestion to increase the conditioning fluid temperature (e.g., directed through the evaporator 112, 130, 148, 254) and / or reduce the cooling fluid temperature (e.g., directed through the condenser 110, 128, 146) of one or more of the vapor compression circuits 102, 104, 106, 252. In this way, the expected lift (e.g., the difference between the inlet and / or outlet temperature of the corresponding evaporator and the inlet and / or outlet temperature of the corresponding condenser or heat exchanger) can be reduced. The controller 200 can continue to compare the expected lift (e.g., based on another value or updated value of the detected operating parameter) with a threshold value, and when the threshold value is met, the controller 200 can begin operation of the vapor compression system 100 or the heat pump system 250.

[0072] Figure 8is a flow chart of an embodiment of a method 700 for controlling the operation (e.g., controlling startup) of a vapor compression system 100 and / or a heat pump system 250. That is, the method 700 can be used to coordinate the startup of the vapor compression system 100 or the heat pump system 250. For example, the controller 200 can be configured to implement and / or execute the method 700 to control various components of the vapor compression system 100 or the heat pump system 250. In other embodiments, the method 700 can be implemented by another controller (e.g., a dedicated controller for the vapor compression system 100, a dedicated controller for the heat pump system 250), more than one controller, or other suitable control system. It should also be noted that additional steps can be performed with respect to the method 700. In addition, certain steps of the depicted method 700 can be removed, modified, and / or performed in a different order.

[0073] Method 700 may be implemented to prevent startup of vapor compression system 100 or heat pump system 250 based on a determination that detected startup conditions of vapor compression system 100 or heat pump system 250 may cause one or more of compressors 108, 126, 144, 256, 258 to surge (e.g., may cause an unacceptable risk of surge). Thus, similar to blocks 602 and 604 of method 600, at blocks 702 and 704, controller 200 may receive a signal to initiate startup of vapor compression system 100 or heat pump system 250, and may determine an expected lift of each of compressors 108, 126, 144, 256, 258 based on the startup conditions.

[0074] Using the expected lift determined in block 704, the method may continue to block 706 and determine a lower frequency limit (e.g., a lower frequency set point, Hzmin) to be applied by the VSD 124, 142, 160, 270, 278 to achieve the expected lift. That is, in some embodiments, the controller 200 may control the VSD 124, 142, 160, 270, 278 to adjust the frequency of the electric power supplied to the motors 122, 140, 158, 268, 276 of the compressors 108, 126, 144, 256, 258, respectively, without reducing the frequency below the lower frequency set point to avoid a surge condition in one or more of the compressors 108, 126, 144, 256, 258. Thus, the lower frequency set point may be determined based on the characteristics of the vapor compression circuit 102, 104, 106, 252 and / or the startup operating parameters. The lower frequency limit for each compressor 108, 126, 144, 256, 258 may be calculated according to the techniques described in EP2751430 (which document is hereby incorporated by reference in its entirety) and may indicate a respective rotational speed (e.g., a lower speed limit) at which the compressor 108, 126, 144, 256, 258 may operate while avoiding or substantially avoiding a surge condition. In fact, the lower frequency limit may be calculated based on the expected or desired position of the PRV 118, 136, 154, 264, 272 and / or the VGD 120, 138, 156, 266, 274, the temperature of the cooling fluid and / or conditioning fluid directed through the vapor compression circuit 102, 104, 106, 252, etc. It should be noted that the following discussion is described in the context of the vapor compression system 100 or the heat pump system 250 receiving power at a frequency of 50 Hz from a power source (e.g., a utility grid, a power grid). However, it should be appreciated that the vapor compression system 100 or the heat pump system 250 may receive power from a power source at any suitable frequency (eg, 48 Hz, 60 Hz).

[0075] At block 708, the controller 200 may compare the lower frequency set point of each compressor 108, 126, 144, 256, 258 to a threshold value to determine whether commencing operation of the vapor compression system 100 or the heat pump system 250 may cause one or more of the compressors 108, 126, 144, 256, 258 to experience a surge condition. In some embodiments, the threshold value may correspond to an upper frequency limit (e.g., 50 Hz) of the power supply that supplies power to the VSDs 124, 142, 160, 270, 278 associated with each compressor 108, 126, 144, 256, 258, respectively. However, it should be noted that in some embodiments, the threshold value may be adjusted (e.g., multiplied) by a ratio value (e.g., a safety factor value, a constant) to reduce the likelihood of a surge condition occurring. In some embodiments, the ratio value may be 0.96 or another suitable value. Thus, while a power source configured to power the VSDs 124, 142, 160, 270, 278 may operate at 50 Hz, the threshold (eg, based on the supplied power and the ratio value) may be set at 48 Hz to limit the likelihood of a surge condition.

[0076] Based on determining (e.g., by controller 200) that the determined lower frequency set point of each of compressors 108, 126, 144, 256, 258 does not exceed the threshold, method 700 can continue to box 710, and controller 200 can begin operation of vapor compression system 100 or heat pump system 250 (e.g., vapor compression circuits 102, 104, 106 having compressors 108, 126, 144 whose determined lower frequency set points do not exceed the threshold, vapor compression circuits having compressors 256, 258 whose determined lower frequency set points do not exceed the threshold).

[0077] Based on a determination (e.g., by controller 200) that a determined lower frequency set point (e.g., based on detected operating conditions and / or a calculated expected lift calculation) does exceed a threshold, method 700 may continue to box 712 and prevent operation (e.g., keep it started) of the vapor compression system 100 or the heat pump system 250 (e.g., the vapor compression circuits 102, 104, 106 having compressors 108, 126, 144 whose determined lower frequency set points exceed the threshold, the vapor compression circuits 256, 258 having compressors whose determined lower frequencies exceed the threshold).

[0078] At block 714, the controller 200 may determine an adjustment amount to one or more operating parameters of the vapor compression system 100 or the heat pump system 250 that may enable operation of the vapor compression system 100 or the heat pump system 250. For example, increasing the conditioning fluid temperature at the evaporator 112, 130, 148, 254 and / or decreasing the cooling fluid temperature at the condenser 110, 128, 146 or a heat exchanger of a cascade system associated with the heat pump system 250 may reduce the expected lift that the corresponding compressor is expected to achieve. As the expected lift decreases, the lower limit of the frequency at which the expected lift can be achieved may also decrease. Thus, upon determining that the lower frequency set point exceeds a threshold, the controller 200 can be configured to determine an amount by which the expected lift of one or more of the compressors 108, 126, 144, 256, 258 should be reduced (e.g., by increasing the temperature of the conditioning fluid in the evaporator 112, 130, 148, 254 and / or decreasing the temperature of the cooling fluid in the condenser 110, 128, 146 or a heat exchanger of a cascade system associated with the heat pump system 250).

[0079] For example, based on detected operating conditions (e.g., before the vapor compression system 100 is started), the controller 200 can determine that the lower frequency set point of the compressor 108 is 55 Hz (e.g., the lower frequency set point exceeds a threshold of 50 Hz or 48 Hz). Using equation (1) below, the controller 200 can determine the amount of adjustment to be applied to the desired lift to enable starting the vapor compression system 100.

[0080] Adjustment percentage of expected lift = (1 – (threshold / Hzmin)) * 100(1)

[0081] Thus, using the above example, upon determining that the desired lift of the compressor 108 corresponds to a lower frequency set point (e.g., Hzmin) of 55 Hz, the controller 200 may divide the threshold value (e.g., 48 Hz) by the lower frequency set point to yield a ratio of 0.87. The ratio value may then be subtracted from 1 and multiplied by 100 to determine the amount of adjustment required to apply to the desired lift (e.g., 13%).

[0082] Similar to box 612 of method 600, at box 716, the controller 200 may output a notification to the user indicating that one or more of the compressors 108, 126, 144, 256, 258 of the vapor compression system 100 or the heat pump system 250 are susceptible to surge if started under current conditions. In some embodiments, the notification may be displayed on the interface 202 of the controller 200 and may include an alarm or warning message notifying the user of the possibility of surge. Further, the notification may include an indication of an adjustment amount to be applied to the calculated expected lift of one of the compressors 108, 126, 144, 256, 258 to enable operation of the vapor compression system 100 or the heat pump system 250. That is, using the above example, the notification may include an indication to reduce the expected lift of the first vapor compression circuit 102 by 13% (e.g., (1-(48 Hz / 55 Hz) * 100). As described above, in certain embodiments, the expected lift of the compressors 108, 126, 144 may be determined based on the difference between the inlet and / or outlet temperature of the conditioning fluid at the evaporators 112, 130, 148 and the inlet and / or outlet temperature of the cooling fluid at the condensers 110, 128, 146 of the respective vapor compression circuits 102, 104, 106, while the expected lift of the compressors 256, 258 may be determined based on the difference between the inlet and / or outlet temperature of the conditioning fluid 280 at the evaporator 254 and the inlet and / or outlet temperature of the cooling fluid at the heat exchanger of the cascade system associated with the heat pump system 250. Alternatively, the expected lift may be determined based on the pressure ratio between the suction pressure of the compressors 108, 126, 144, 256, 258 and the discharge pressure of the compressors 108, 126, 144, 256, 258. Additionally, in certain embodiments, the inlet and / or outlet temperatures of the evaporators 112 , 130 , 148 , 254 may be used to determine an expected suction pressure of the compressors 108 , 126 , 144 , 256 , 258 , which may be compared to the discharge pressure of the compressors 108 , 126 , 144 , 256 , 258 to determine a pressure ratio, thereby enabling determination of an expected lift of the compressors 108 , 126 , 144 , 256 , 258 .

[0083] Thus, the notification may include a recommendation to increase the conditioning fluid temperature at the evaporator 112, 130, 148, 254, to reduce the cooling fluid temperature at the condenser 110, 128, 146 of one of the vapor compression circuits 102, 104, 106, and / or to reduce the conditioning fluid temperature of a heat exchanger of a cascade system associated with the heat pump system 250 in order to adjust (e.g., reduce) the expected lift of the corresponding compressor 108, 126, 144, 256, 258, thereby enabling the compressor 108, 126, 144, 256, 258 to be started in a manner that reduces the likelihood of surge.

[0084] As the expected lift decreases (e.g., by increasing the cooling fluid temperature and / or decreasing the conditioning fluid inlet temperature), the controller 200 may continuously monitor the lower frequency set point of each compressor 108, 126, 144, 256, 258 based on the expected lift as determined based on the startup conditions. Upon determining that the lower frequency set point associated with each compressor 108, 126, 144, 256, 258 is below a threshold, the method 700 may continue to block 710 and the controller 200 may begin operation of the vapor compression system 100 or the heat pump system 250.

[0085] The present disclosure may provide one or more technical effects useful in the operation of an HVAC&R system. For example, an HVAC&R system may include a vapor compression system having a plurality of vapor compression circuits (e.g., vapor compression stages) arranged in series countercurrent flow, a heat pump system having an open-loop vapor compression circuit, and / or a vapor compression system having a single vapor compression circuit. In certain embodiments, the vapor compression system and / or the heat pump system may have a plurality of compressors, each of which is configured to operate with a VSD, and the vapor compression system and / or the heat pump system may be configured to control each of the VSDs to operate the compressor at a variable speed based on the needs of the vapor compression system or the heat pump system. Further, the vapor compression system and the heat pump system discussed herein may include a flow reduction device configured to further control the operating parameters of the compressor. The vapor compression system or the heat pump system may utilize various methods to control the speed of the FRD and the variable speed compressor based on calculated parameters and / or feedback provided by sensors of the vapor compression system or the heat pump system. By monitoring the operating conditions of the vapor compression system and / or the heat pump system, a head pressure value (e.g., a lift value) for each compressor can be determined, which can be used to limit the operation of the vapor compression system or the heat pump system (e.g., limit startup) during a surge condition. If the expected lift (e.g., head pressure) based on the operating conditions of the vapor compression system or the heat pump system exceeds a specified threshold, a notification can be sent to inform the user that the system is susceptible to surge. Further, the notification can include a suggestion to adjust one or more operating parameters of the vapor compression system or the heat pump system to enable the operation of the vapor compression system or the heat pump system. Still further, the expected head pressure value can be used to determine the frequency lower limit of each of the compressors in the vapor compression system or the heat pump system, and the frequency lower limit can also be compared with a threshold to determine whether the system is susceptible to surge. In this way, an adjustment amount to one or more operating parameters of the vapor compression system or the heat pump system can be calculated, and the adjustment amount is sent to the user to enable the operation of the vapor compression system or the heat pump system. The technology discussed herein enables more efficient operation (e.g., increased isentropic efficiency) of a vapor compression system or a heat pump system by limiting the operation of the vapor compression system or the heat pump system when operating conditions indicate a potential surge condition. By doing so, the operation, maintenance, and life of the vapor compression system or the heat pump system can be improved. The technical effects and technical problems in the specification are examples and are not limiting. It should be noted that the embodiments described in the specification may have other technical effects and may solve other problems.

[0086] Although only certain features and embodiments have been shown and described, many modifications and changes may occur to those skilled in the art, such as changes in the size, dimensions, structure, shape and proportion of various elements, values ​​of parameters such as temperature and pressure, mounting arrangements, use of materials, colors, orientations, etc., without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. Therefore, it should be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the present disclosure.

[0087] In addition, in order to provide a concise description of the exemplary embodiments, not all features of the actual implementation may be described, such as those features that are not relevant to the best mode currently contemplated, or those features that are not relevant to implementation. It should be understood that in the development of any such actual implementation, as in any engineering or design project, many implementation-specific decisions may be made. Such development work may be complex and time consuming, but is nevertheless a routine task of design, production, and manufacture for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0088] The technology presented and claimed herein is cited and applied to material objects and specific examples of a practical nature that demonstrably improve the art and are therefore not abstract, intangible, or purely theoretical. Further, if any claim appended to the end of this specification contains one or more elements designated as "means for [performing] ... [function]" or "steps for [performing] ... [function]," such elements are intended to be interpreted under 35 U.S.C. § 112(f). However, for any claim containing elements designated in any other manner, such elements are intended not to be interpreted under 35 U.S.C. § 112(f).

Claims

1. A heating, ventilation, air conditioning and refrigeration (HVAC&R) system comprising: A vapor compression system, the vapor compression system comprising: a vapor compression circuit including a compressor system configured to direct a working fluid through the vapor compression circuit to provide a heat exchange relationship between the working fluid and a cooling fluid, a conditioning fluid, or both; as well as a controller comprising a memory and processing circuitry, wherein the memory comprises instructions stored thereon that, when executed by the processing circuitry, cause the processing circuitry to: receiving a signal to initiate operation of the vapor compression system; receiving sensor data indicative of an operating condition of the vapor compression system; determining an expected lift of the compressor system based on the operating conditions of the vapor compression system; comparing the expected lift of the compressor system to a threshold value; and Operation of the vapor compression system is controlled based on a comparison of the expected lift to the threshold value.

2. The HVAC&R system of claim 1 , wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to prevent operation of the vapor compression system in response to determining that the expected lift of the compressor system exceeds the threshold.

3. The HVAC&R system of claim 2, wherein the instructions, when executed by the processing circuit system, cause the processing circuit system to output a notification to a user in response to the determination that the expected lift of the compressor system exceeds the threshold, wherein the notification includes an indication that startup of the vapor compression system is prevented.

4. The HVAC&R system of claim 3, wherein the notification includes a recommendation to reduce the expected lift of the compressor system to enable the operation of the vapor compression system.

5. The HVAC&R system of claim 1 , wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to enable operation of the vapor compression system in response to determining that the expected lift of the compressor system does not exceed the threshold.

6. The HVAC&R system of claim 1 , wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to: determining a difference between an inlet temperature of an evaporator of the vapor compression circuit and an inlet temperature of a condenser of the vapor compression circuit; and The expected lift is determined based on the difference.

7. The HVAC&R system of claim 1 , wherein the operating conditions include an inlet temperature of an evaporator of the vapor compression circuit, an outlet temperature of the evaporator of the vapor compression circuit, an inlet temperature of a condenser of the vapor compression circuit, an outlet temperature of the condenser of the vapor compression circuit, or any combination thereof.

8. The HVAC&R system of claim 1 , wherein the vapor compression system comprises a plurality of vapor compression circuits, the plurality of vapor compression circuits including the vapor compression circuit, each of the plurality of vapor compression circuits being configured to receive the cooling fluid and to receive the conditioning fluid, and the plurality of vapor compression circuits being arranged in a series countercurrent arrangement relative to respective flows of the cooling fluid and the conditioning fluid directed through the plurality of vapor compression circuits.

9. A heating, ventilation, air conditioning and refrigeration (HVAC&R) system comprising: a vapor compression system comprising a plurality of vapor compression circuits, wherein each of the plurality of vapor compression circuits comprises a compressor configured to direct a working fluid through the vapor compression circuit to establish a heat exchange relationship between the working fluid and a conditioning fluid; as well as a controller comprising a memory and processing circuitry, wherein the memory comprises instructions stored thereon that, when executed by the processing circuitry, cause the processing circuitry to: receiving a signal to initiate operation of the vapor compression system; receiving sensor data indicative of an operating condition of the vapor compression system; determining an expected lift of a corresponding compressor of each of the plurality of vapor compression circuits based on the operating conditions of the vapor compression system; comparing the expected lift to a threshold value; and Operation of the vapor compression system is controlled based on a comparison of the expected lift to the threshold value.

10. The HVAC&R system of claim 9, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to prevent operation of the vapor compression system in response to determining that the expected lift of the corresponding compressor of at least one of the plurality of vapor compression circuits exceeds the threshold.

11. The HVAC&R system of claim 10, wherein the instructions, when executed by the processing circuit system, cause the processing circuit system to send a notification to a user in response to the determination that the expected lift of the corresponding compressor of the at least one of the plurality of vapor compression circuits exceeds the threshold, wherein the notification includes an indication that startup of the vapor compression system is prevented.

12. The HVAC&R system of claim 9, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to enable operation of the vapor compression system in response to determining that the expected lift of the corresponding compressor of each of the plurality of vapor compression circuits does not exceed the threshold.

13. The HVAC&R system of claim 9 , wherein the operating conditions include a respective inlet temperature of an evaporator of each of the plurality of vapor compression circuits, a respective outlet temperature of the evaporator of each of the plurality of vapor compression circuits, a respective inlet temperature of a condenser of each of the plurality of vapor compression circuits, a respective outlet temperature of the condenser of each of the plurality of vapor compression circuits, or any combination thereof.

14. The HVAC&R system of claim 9, wherein the respective compressor of each of the plurality of vapor compression circuits comprises pre-rotation vanes, a variable geometry diffuser, a variable speed drive, or a combination thereof.

15. A tangible, non-transitory computer-readable medium containing instructions executable by processing circuitry of a vapor compression system, the instructions, when executed by the processing circuitry, causing the processing circuitry to: receiving a signal to initiate operation of the vapor compression system; receiving sensor data indicative of an operating condition of the vapor compression system; determining an expected lift for each of one or more compressors of the vapor compression system based on the operating conditions of the vapor compression system; determining a respective lower frequency limit for each of the one or more compressors based on the expected lift; comparing the corresponding lower frequency limit of each of the one or more compressors to a threshold value; and Operation of the vapor compression system is controlled based on a comparison of the respective lower frequency limit of each of the one or more compressors to the threshold value.

16. The computer-readable medium of claim 15, wherein the respective lower frequency limit for each of the one or more compressors is determined based on an expected position of a pre-rotation vane system of the compressor, an expected position of a variable geometry diffuser of the compressor, a temperature of a cooling fluid directed through the vapor compression system, or any combination thereof.

17. The computer-readable medium of claim 15, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to: Operation of the vapor compression system is inhibited in response to determining that the corresponding lower frequency limit of at least one of the one or more compressors exceeds the threshold value.

18. The computer-readable medium of claim 17, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to: In response to determining that the corresponding frequency lower limit of at least one of the one or more compressors exceeds the threshold, a notification is sent to a user, wherein the notification includes an indication that startup of the vapor compression system is prevented and a suggestion to reduce the expected lift of at least one of the one or more compressors to enable operation of the vapor compression system.

19. The computer-readable medium of claim 15, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to: Operation of the vapor compression system is initiated in response to determining that the respective lower frequency limit of each of the one or more compressors does not exceed the threshold value.

20. The computer-readable medium of claim 15, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to: determining a difference between an inlet temperature of an evaporator corresponding to a compressor of the one or more compressors and an inlet temperature of a condenser corresponding to the compressor of the one or more compressors; and The expected lift of the compressor of the one or more compressors is determined based on the difference.

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