Systems and methods for providing compressor cooling

Abstract

The vapor compression system includes a primary loop and a secondary loop. The primary loop includes a dynamic compressor operable to compress a refrigerant, a condenser fluidly connected to the dynamic compressor, a first expansion device fluidly connected to the condenser, and an evaporator fluidly connected to the first expansion device and the dynamic compressor. The dynamic compressor includes a housing, a shaft supported within the housing by bearings, an impeller connected to the shaft, a motor operably connected to the shaft and rotatably driving the shaft, and a drive operable to control the motor. The secondary loop includes a second expansion device fluidly connected to the condenser, a heat exchanger fluidly connected to the second expansion device, the condenser, and the dynamic compressor, and a supply duct fluidly connected between the heat exchanger and the dynamic compressor for supplying refrigerant flow to the bearing.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 17 / 930,807, filed September 9, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] The field of the disclosure relates generally to heating, ventilation, and air conditioning (HVAC) systems, and more specifically to control systems for HVAC systems. [Background technology]

[0003] Dynamic compressors, including centrifugal compressors, are commonly used in process industries and heating, ventilation, and air conditioning (HVAC) systems. The compressor is typically connected to a motor via a shaft that supports multiple compression stages. A drive controls the motor to rotate the compression stages at selected rotational speeds and load conditions to compress the refrigerant to a specified demand. The motor speed and load can be controlled to operate the compressor under a wide range of operating conditions.

[0004] During operation, the drive, motor, and compressor bearings can reach high temperatures, which, if not addressed, can increase the risk of mechanical failure due to overheating. Many existing cooling systems bypass low-temperature refrigerant from the main flow path to components that require cooling. However, using liquid refrigerant for cooling creates an opportunity for the liquid to get into the bearings or high-speed impeller, reducing compressor performance and lifespan. Thus, there is a need for a compressor cooling system that uses only gas refrigerant as the cooling fluid.

[0005] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to better understand the various aspects of the present disclosure. As such, it should be understood that these statements are to be read in this light, and not as admissions of prior art. Summary of the Invention

[0006] One aspect of the present disclosure relates to a vapor compression system including a primary loop and a secondary loop. The primary loop includes a dynamic compressor operable to compress a refrigerant, a condenser fluidly connected to the dynamic compressor, a first expansion device fluidly connected to the condenser, and an evaporator fluidly connected to the first expansion device and the dynamic compressor. The dynamic compressor includes a housing, a shaft supported within the housing by bearings, an impeller connected to the shaft, a motor operably connected to the shaft and driving rotation of the shaft, and a drive operable to control the motor. The secondary loop includes a second expansion device fluidly connected to the condenser, a heat exchanger fluidly connected to the second expansion device, the condenser, and the dynamic compressor, and a supply duct fluidly connected between the heat exchanger and the dynamic compressor for supplying a flow of refrigerant to the bearing.

[0007] Another aspect of the present disclosure relates to a controller for a compressor system including a dynamic compressor and a cooling device, the cooling device including a heat exchanger and a supply duct fluidly connected between the heat exchanger and the dynamic compressor, the controller including a processor and a memory having stored thereon instructions that program the processor to operate the dynamic compressor to compress a refrigerant, operate the cooling device to supply a flow of refrigerant to a bearing of the dynamic compressor through the supply duct, determine whether a condition is met, and, if the condition is met, adjust a position of a valve in fluid communication between the dynamic compressor and the cooling device.

[0008] Another aspect of the present disclosure relates to a compressor system including a dynamic compressor operable to compress a refrigerant and a cooling device, the dynamic compressor including a housing, a shaft supported within the housing by a bearing, and an impeller connected to the shaft, the cooling device including a heat exchanger fluidly connected to the dynamic compressor, a supply duct fluidly connected between the heat exchanger and the dynamic compressor for supplying a flow of refrigerant to the bearing, a valve fluidly connected to the supply duct and selectively positionable to allow refrigerant to flow through the supply duct, and a controller operable to control the valve.

[0009] Various refinements exist to the features described in connection with the above aspects of the present disclosure. Additional features may also be incorporated into the above aspects of the present disclosure. These refinements and additional features may exist individually or in any combination. For example, the various features discussed below in connection with any of the illustrated embodiments of the present disclosure may be incorporated alone or in any combination into any of the above aspects of the present disclosure. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a dynamic compressor according to an embodiment. [Figure 2] 2 is a cross-sectional view of the dynamic compressor of FIG. 1 taken along line 2-2 with the external conduit removed. [Figure 3] FIG. 3 is a block diagram of a control system for the dynamic compressor shown in FIGS. 1 and 2. [Figure 4] FIG. 3 is a schematic diagram of a first example vapor compression system in which the dynamic compressor shown in FIGS. 1 and 2 can be installed. [Figure 5] FIG. 3 is a schematic diagram of a second example vapor compression system in which the dynamic compressor shown in FIGS. 1 and 2 may be installed. [Figure 6] FIG. 3 is a schematic diagram of a third example vapor compression system in which the dynamic compressor shown in FIGS. 1 and 2 may be installed. [Figure 7] FIG. 7 is a schematic diagram of an alternative embodiment of the third example vapor compression system shown in FIG. 6. [Figure 8]FIG. 3 is a schematic diagram of a fourth example vapor compression system in which the dynamic compressor shown in FIGS. 1 and 2 may be installed. [Figure 9] FIG. 3 is a schematic diagram of a fifth example vapor compression system in which the dynamic compressor shown in FIGS. 1 and 2 can be installed. [Figure 10] 1 is an example of a control algorithm for controlling the flow of the first coolant to the bearing assembly. [Figure 11] 1 is a first example control algorithm for controlling the flow of a second refrigerant to a motor. [Figure 12] 10 is a second example control algorithm for controlling the flow of a second refrigerant to a drive unit. [Figure 13] 1 is a first example control algorithm for controlling the flow of a third refrigerant to a motor. [Figure 14] 10 is a second example control algorithm for controlling the flow of a third refrigerant to a drive unit. [Figure 15] 15 is a flow chart of the example control algorithm shown in Figures 10 to 14. Corresponding reference characters indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION OF THE INVENTION

[0011] For simplicity, examples are described with respect to a centrifugal compressor, although the methods and systems described herein may be applied to any suitable compressor. The bearings, motor, and drive of a dynamic compressor may be cooled with vapor injection by diverting a portion of the main flow through an auxiliary loop that includes a heat exchanger or flash tank. The gaseous refrigerant discharged from the heat exchanger or flash tank may be selectively supplied to the bearings, motor, or drive based on the measured and desired temperatures of these components.

[0012] Referring to FIG. 1, a two-stage refrigerant compressor is generally designated 100. The compressor 100 is operable to compress a working fluid (e.g., a refrigerant) and includes a compressor housing 102 forming at least one sealed cavity for achieving each stage of refrigerant compression. The compressor 100 includes a first refrigerant inlet 110 for introducing refrigerant vapor into a first compressor stage (not labeled in FIG. 1), a first refrigerant outlet 114, a refrigerant transfer conduit 112 for transferring compressed refrigerant from the first compressor stage to a second compressor stage, a second refrigerant inlet 118 for introducing refrigerant vapor into the second compressor stage (not labeled in FIG. 1), and a second refrigerant outlet 120. The refrigerant transfer conduit 112 is operably connected at opposite ends to the first refrigerant outlet 114 and the second refrigerant inlet 118, respectively. The refrigerant transfer conduit 112 further includes a port 122 for adding or removing flow between the first and second compressor stages. A second refrigerant outlet 120 delivers compressed refrigerant from the second compressor stage to a refrigeration system in which the compressor 100 is incorporated.

[0013] Referring to FIG. 2 , the compressor housing 102 encloses a first compressor stage 124 and a second compressor stage 126 at opposite ends of the compressor 100. The first compressor stage 124 includes a first compression mechanism 106 configured to impart kinetic energy to a refrigerant entering through a first refrigerant inlet 110. In some embodiments, the first compression mechanism 106 is an impeller. The kinetic energy imparted to the refrigerant by the first compression mechanism 106 is converted to an increase in refrigerant pressure as the refrigerant velocity slows upon transfer to a sealed cavity (e.g., a diffuser) formed within a volute 132. The first compressor stage 124 further includes a first variable inlet guide vane (VIGV) 134 disposed upstream of the first compression mechanism 106 from the first refrigerant inlet 110. The first VIGV 134 includes a plurality of vanes whose positions can be controlled to introduce pre-swirl into the gaseous refrigerant entering the first refrigerant inlet 110 .

[0014] Similarly, the second compressor stage 126 includes a second compression mechanism 116 configured to impart kinetic energy to the refrigerant transferred from the first compressor stage 124 and entering through the second refrigerant inlet 118. In some embodiments, the second compression mechanism 116 is an impeller. The kinetic energy imparted to the refrigerant by the second compression mechanism 116 is converted into an increase in refrigerant pressure as the refrigerant velocity slows as it is transferred into a sealed cavity (e.g., a diffuser) formed within the volute 132. The compressed refrigerant exits the second compression stage 126 through a second refrigerant outlet 120 (not shown in FIG. 2 ). The second compression stage 126 also includes a second variable inlet guide vane (VIGV) 136 positioned upstream of the second compression mechanism 116 from the second refrigerant inlet 118. The second VIGV 136 includes a plurality of vanes with controllable positions to introduce pre-swirl into the gaseous refrigerant entering the second refrigerant inlet 118.

[0015] The first compression mechanism 106 and the second compression mechanism 116 are connected to opposite ends of the shaft 104. The shaft 104 is operably connected to a motor 108 positioned between the first compression mechanism 106 and the second compression mechanism 116, which rotate at a selected rotational speed to compress the refrigerant to a preselected pressure that exits a second refrigerant outlet 120 (not shown in FIG. 2 ). The compressor 100 may incorporate any suitable motor, including, but not limited to, an electric motor. The motor 108 may include a motor temperature sensor (not shown) operable to determine the motor temperature. The motor temperature sensor may be a thermocouple, thermistor, resistance temperature detector (RTD), or any other suitable sensor. The shaft 104 is rotatably supported by a gas foil bearing assembly 200 positioned within a sleeve 252 of each bearing housing 250 / 250a, as described in more detail below. Each bearing housing 250 / 250a includes mounting structure for connecting the respective bearing housing 250 / 250a to the compressor housing 102.

[0016] FIG. 3 illustrates an exemplary embodiment of a system 600 including the dynamic compressor 100. The system 600 may be any suitable system in which the dynamic compressor 100 may be installed. The compressor 100 includes a compressor housing 102, a compression mechanism 607, a motor 108, a speed sensor 617, a pressure sensor 609, and a controller 610. In this embodiment, the dynamic compressor 100 is a two-stage centrifugal compressor, and the compression mechanism 607 is an impeller for each stage. In other embodiments, the dynamic compressor 100 may be an axial compressor, and the compression mechanism 607 may be an axial rotor. The speed sensor 617 measures the rotational speed of the compressor 100, and the pressure sensor 609 measures pressure at various points along the compressor flow path, including the refrigerant inlet and refrigerant outlet. Additional sensors may be installed in the compressor 100 to provide data regarding its operation, including, but not limited to, temperature sensors, flow sensors, current sensors 608, voltage sensors, rotational speed sensors, and other suitable sensors. Compressor 100 is not limited to a particular configuration within system 600 and may be configured similarly to or different from compressor 100 described in Figures 1 and 2. System 600 further includes unloading device 601, variable frequency drive 616 operable to control motor 108, and user interface 615.

[0017] The controller 610 is operatively connected to the dynamic compressor 100 and controls its operation based in part on the measured parameters described above. The controller 610 includes a processor 611, a memory 612, and an unload interface 614. The memory 612 stores instructions that program the processor 611 to determine whether the bearing assembly 200, the motor 108, and / or the drive 616 require cooling, as discussed in further detail below. The system 600 includes an interface for connecting the controller 610 to the drive 616 and a motor interface 613 for connecting the drive 616 to the motor 108. In certain embodiments, the drive 616 operates under the control of the controller 610. In further embodiments, the drive 616 is part of the controller 610. The drive 616 may include a drive temperature sensor (not shown) capable of determining the temperature of the drive. The drive temperature sensor may be a thermocouple, a thermistor, a resistance temperature detector (RTD), or other suitable sensor. The system 600 further includes an unload interface 614 for connecting the controller 610 to the unload device 601 .

[0018] The controller 610 is operatively coupled to the unloading device 601 via an unloading interface 614, which removes and / or reduces the load on the compressor 100 during startup and shutdown routines, during detected surge events, and when directed by the controller 610. In this exemplary embodiment, the unloading device 601 is a variable inlet guide vane (VIGV) at the inlet of each impeller stage ( FIG. 2 ). In other embodiments, the unloading device 601 may be a variable diffuser, a bypass valve, or any suitable device or combination of devices that reduces the load on the compressor 100. The unloading device 601 may additionally or alternatively be used as a loading device to increase the load on the compressor 100. The controller 610 is configured to control at least one operating parameter of the unloading device 601, such as the position of each VIGV.

[0019] System 600 further includes a user interface 615 configured to output (e.g., display) and / or receive (e.g., from a user) information related to system 600. In some embodiments, user interface 615 is configured to receive activation and / or deactivation input from a user to activate and deactivate (i.e., turn on and off) system 600 or otherwise enable operation of system 600. Additionally, in some embodiments, user interface 615 is configured to output information related to one or more operational characteristics of system 600, including, but not limited to, warning indicators such as severity alerts, occurrence alerts, fault alerts, motor speed alerts, and other suitable information.

[0020] The user interface 615 may include any suitable input and output devices that enable the user interface 615 to function as described herein. For example, the user interface 615 may include input devices, including, but not limited to, a keyboard, a mouse, a touchscreen, a joystick, a throttle, buttons, switches, and / or other input devices. Additionally, the user interface 615 may include output devices, including, but not limited to, a display (e.g., a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display), a speaker, indicator lights, gauges, and / or other output devices. Furthermore, the user interface 615 may be part of another component, such as a system controller (not shown). In other embodiments, the user interface 615 is not included.

[0021] The controller 610 is generally configured to control the operation of the dynamic compressor 100. The controller 610 may control operation through programming and instructions from another device or controller, or may be integrated with the system 600 through a system controller. In some embodiments, for example, the controller 610 receives user input from a user interface 615 and controls one or more components of the system 600 in response to such user input. For example, the controller 610 may control the motor 108 based on user input received from the user interface 615. In some embodiments, the system 600 may be controlled by a remote control interface. For example, the system 600 may include a communications interface (not shown) configured for connection to a wireless control interface that enables remote control and activation of the system 600. The wireless control interface may be embodied on a portable computing device, such as a tablet or smartphone.

[0022] The controller 610 may generally include any suitable computer and / or other processing unit, including any suitable combination of computers, processing units, etc., communicatively coupled to each other and capable of operating independently or in conjunction with each other (e.g., the controller 610 may form all or part of a controller network). The controller 610 may include one or more modules or devices, one or more of which may be housed within the system 600 or located remotely from the system 600. The controller 610 may be part of or separate from the compressor 100, or may be part of a system controller in an HVAC system. The controller 610 and / or components of the controller 610 may be integrated or incorporated within other components of the system 600. The controller 610 may include one or more processors 611 and associated memory devices 612 configured to perform various computer-implemented functions (e.g., performing the calculations, decisions, and functions disclosed herein).

[0023] As used herein, the term "processor" refers not only to integrated circuits, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits, and other programmable circuits. Additionally, the memory device 612 of the controller 610 can generally be or include memory elements, including, but not limited to, computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, compact disk read-only memories (CD-ROMs), magneto-optical disks (MODs), digital versatile disks (DVDs), and / or other suitable memory elements. Such memory device 612 may generally be configured to store suitable computer-readable instructions that, when executed by processor 611, configure or cause controller 610 to perform various functions described herein, including, but not limited to, controlling system 600, controlling operation of motor 108, receiving input from user interface 615, providing output to an operator via user interface 615, controlling unloading device 601, and / or various other suitable computer-implemented functions.

[0024] FIG. 4 is a schematic diagram of a first example vapor compression system 700 in which the dynamic compressor 100 of FIGS. 1 and 2 may be installed. The system 700 shown in FIG. 4 has a single closed refrigerant loop 310 including the compressor 100, a condenser 320, a first expansion device 330, and an evaporator 340. In a further embodiment (not shown), the system 700 may include multiple refrigerant loops to accommodate multiple compressors 100. Refrigerant enters the dynamic compressor 100 at a first refrigerant inlet 110 as a low-pressure, low-temperature gas. The dynamic compressor 100 applies kinetic energy to the refrigerant, converting it into a pressure increase, and the refrigerant exits the dynamic compressor 100 at a second refrigerant outlet 120 as a high-pressure, high-temperature gas. The refrigerant enters a condenser 320 fluidly connected to the compressor 100, where it is condensed into a heat exchanger 330. out is removed, converting the refrigerant gas into a high-pressure, high-temperature liquid.

[0025] The condenser 320 is fluidly connected to a first expansion device 330, which reduces the pressure of the refrigerant. In some embodiments, the pressure can be reduced until the current temperature of the liquid refrigerant reaches its boiling point temperature at that pressure, causing a portion of the liquid refrigerant to boil and turn into a gas, resulting in a two-phase mixture. The first expansion device 330 may be a fixed orifice, a thermal expansion valve, an electronic expansion valve, or any type of expansion device that enables the vapor compression system 700 to function as described herein. The first expansion device 330 is fluidly connected to an evaporator 340, which receives at its inlet a low-pressure, low-temperature liquid refrigerant or a two-phase mixture of liquid and gas refrigerant. In the evaporator 340, the refrigerant absorbs heat Qin and undergoes a phase change from liquid to gas. The evaporator 340 is fluidly connected to the compressor 100, and the cycle begins again.

[0026] Figure 5 is a schematic diagram of a second example vapor compression system 800 in which the dynamic compressor 100 of Figures 1 and 2 may be installed. System 800 includes a primary refrigerant loop 410 that includes the dynamic compressor 100, a condenser 320, a first stream 492 of a heat exchanger 490, a first expansion device 330, and an evaporator 340. System 800 also includes a secondary refrigerant loop 460 that is fluidly connected to a portion of the primary refrigerant loop 410 and controlled by an economization valve 470, which will be described in more detail herein.

[0027] Secondary refrigerant loop 460 includes second expansion device 480, second stream 494 of heat exchanger 490, economization valve 470, second compressor stage 126 of the compressor (FIG. 2), and condenser 320. In the embodiment shown in FIG. 5, the components of secondary refrigerant loop 460 are fluidly connected in the listed order, and condenser 320 is further coupled to second expansion device 480 to close secondary refrigerant loop 460.

[0028] The economization valve 470 is controlled by the controller 610 to be fully open, partially open, or fully closed, and the state of the economization valve 470 determines whether refrigerant flows through the secondary refrigerant loop 460. That is, when the economization valve 470 is fully closed, all of the refrigerant flows through the primary refrigerant loop 410, and the system 800 operates substantially similarly to the system 700 shown in FIG. 4. When the economization valve 470 is open, the liquid refrigerant exiting the condenser 320 splits into two streams, with most of the refrigerant flowing through the primary refrigerant loop 410 and the remainder bypassing through the secondary refrigerant loop 460. The economization valve 470 may be a solenoid valve, an electronic expansion valve, or any type of valve that enables the system 800 to function as described herein.

[0029] When the economization valve 470 is open, the condenser 320 is fluidly connected to the second expansion device 480, which reduces the pressure of the liquid economizer flow until the liquid refrigerant's current temperature is at its boiling point temperature at that pressure. The refrigerant in the secondary refrigerant loop becomes a two-phase mixture as it enters the heat exchanger 490, where a portion of the liquid refrigerant boils and turns to a gas. The second expansion device can be sized and selected to bypass a specific amount of refrigerant through the secondary refrigerant loop 460 when the economization valve 470 is open, for example, 0 to 20 percent of the total mass flow, or any other amount of refrigerant flow that enables the system 800 to function as described herein.

[0030] In some embodiments, the second expansion device 480 is a thermal expansion valve (TXV) that adjusts the amount of refrigerant flow through the secondary refrigerant loop 460 based on the heat load of the heat exchanger 490. The TXV operates in combination with a valve 496 located downstream of the second stream 494 of the heat exchanger 490. A membrane within the TXV is movable to balance the refrigerant pressure within the valve with the refrigerant pressure upstream of the heat exchanger 490. The movement of the membrane is coupled to a needle that sets the position of the valve, thereby controlling the amount of refrigerant flowing through the secondary refrigerant loop 460. In further embodiments, the second expansion device 480 may be a fixed orifice, an electronic expansion valve, or any type of expansion device that enables the system 800 to function as described herein.

[0031] The refrigerant exits the second expansion device 480 and enters the second stream 494 of the heat exchanger 490 as a low-pressure liquid or two-phase mixture. The second stream 494 is in thermal communication with the first stream 492, which carries the high-pressure liquid refrigerant from the condenser 320 of the primary refrigerant loop 410. The thermal contact between the two streams 492, 494 cools the refrigerant in the first stream 492 and warms and boils the refrigerant in the second stream 494. The cooled refrigerant in the first stream 492 exits the heat exchanger 490 as a low-temperature, high-pressure liquid, and the boiled refrigerant in the second stream 494 exits the heat exchanger 490 as a low-temperature, intermediate-pressure gas. The heat exchanger 490 may be a counterflow heat exchanger, a cross-flow heat exchanger, a parallel-flow heat exchanger, a shell-and-tube heat exchanger, a mixing chamber, or any type of heat exchanger that enables the system 800 to function as described herein. In further embodiments, a flash tank may be used in place of or in addition to heat exchanger 490. Such embodiments are further shown and described below.

[0032] The low temperature, intermediate pressure gas exiting the second stream 494 of the heat exchanger 490 then flows through an economization duct 465 and is injected into the refrigerant transfer conduit 112 (FIG. 2) of the compressor 100, where it mixes with the refrigerant stream of the primary refrigerant loop 410 before reaching the second compressor stage 126. The primary refrigerant loop 410 and the secondary refrigerant loop 460 merge in the second compressor stage 126 and diverge again after the refrigerant leaves the condenser 320.

[0033] FIG. 6 is a schematic diagram of a third example vapor compression system 900 in which the dynamic compressor 100 of FIGS. 1 and 2 may be installed. In addition to all of the components shown and described with respect to the second example vapor compression system 800 shown and described with respect to FIG. 5, the system 900 further includes a refrigeration device 560 forming a part of the secondary refrigerant loop 460. The refrigeration device 560 includes a heat exchanger 490 and a first supply duct 565 fluidly connected between the heat exchanger 490 and the dynamic compressor 100. The secondary refrigerant loop 460 bifurcates downstream of the heat exchanger 490 into an economization duct 465 and a first supply duct 565. A portion of the refrigerant flow in the secondary refrigerant loop 460 flows through the economization duct 465, as described above with respect to the second example vapor compression system 800, and the remainder flows through the first supply duct 565 to provide a first refrigerant flow to at least one bearing assembly 200 of the dynamic compressor 100.

[0034] The first supply duct 565 includes a first valve 570 fluidly connected to the first supply duct 565. The first valve 570 is controlled by the controller 610 and is selectively positionable to allow refrigerant to flow through the first valve 570. When the first valve 570 is fully closed, all of the refrigerant in the secondary refrigerant loop 460 flows through the economization duct 465, and the system 900 operates substantially similarly to the system 800 shown in FIG. 5. When the first valve 570 is fully or partially open, the gas or two-phase refrigerant exiting the heat exchanger 490 splits into two streams, with a portion of the refrigerant flowing through the economization duct 465 and the remainder being bypassed through the first supply duct 565. The first valve 570 may be a solenoid valve (shown in FIG. 6), an electronic expansion valve, or any type of valve that enables the system 900 to function as described herein.

[0035] When the first valve 570 is open, the first supply duct 565 provides a first refrigerant flow to facilitate cooling of at least one bearing assembly 200 of the dynamic compressor 100. In the illustrated embodiment, the first supply duct 565 branches into first, second, and third streams 565a-c that provide the first refrigerant flow to the first radial bearing 200a, the second radial bearing 200b, and the thrust bearing 200c, respectively, of the dynamic compressor 100. In some embodiments, the first, second, and third streams 565a-c may include valves (not shown) operable to control the flow of refrigerant through the first, second, and third streams 565a-c, respectively.

[0036] The refrigeration equipment 560 further includes a return duct 520 fluidly connecting the first supply duct 565 to the dynamic compressor 100 and providing a return flow of refrigerant to the dynamic compressor 100. The return duct 520 collects refrigerant from downstream of the cooled bearings and returns the refrigerant to the inlet 110 of the first compressor stage 124. In the illustrated embodiment, each of the first, second, and third streams 565a-c of the first supply duct 565 join downstream of the respective bearings 200a-c to form the return duct 520. The return flow mixes with the flow of refrigerant upstream of the inlet 110, thereby joining the primary refrigerant loop 410 and the secondary refrigerant loop 460. The return duct 520 is configured to cool the return flow at a temperature T r The return temperature sensor may include a return temperature sensor (not shown) operable to measure the temperature. The return temperature sensor may be a thermocouple, a thermistor, or any suitable temperature sensor.

[0037] An alternative embodiment of the third example vapor compression system 900 is shown in FIG. 7, in which the heat exchanger is replaced with a flash tank 590. Downstream of the condenser 320, the refrigerant flow is throttled through an expansion device 480, reducing the pressure until a portion of the liquid refrigerant boils and forms a two-phase mixture. The flash tank 590 separates the two-phase refrigerant mixture into liquid and gas portions, which branch into the primary refrigerant loop 410 and the secondary refrigerant loop 460, respectively. In certain embodiments, a heat exchanger may be used instead of or in addition to the flash tank 590. The refrigerant then flows along the primary refrigerant loop 410 and the secondary refrigerant loop 460, as described above with respect to FIG. 6.

[0038] FIG. 8 is a schematic diagram of a fourth example vapor compression system 1100 in which the dynamic compressor 100 of FIGS. 1 and 2 may be installed. In addition to the components shown and described with respect to the third example vapor compression system 900 shown in FIG. 6, the refrigeration equipment 560 of the system 1100 further includes a second supply duct 665 fluidly connected between the heat exchanger 490 and the motor 108. The second refrigerant loop 460 bifurcates downstream of the heat exchanger 490 into an economization duct 465, a first supply duct 565, and a second supply duct 665. As described above with respect to the third example vapor compression system 900, a portion of the refrigerant flow in the second refrigerant loop 460 flows through the economization duct 465 and the first supply duct. The remainder of the refrigerant flow in the second refrigerant loop 460 flows through the second supply duct 665 to provide a second refrigerant flow to the motor 108.

[0039] The second supply duct 665 includes a second valve 670 fluidly connected to the second supply duct 665. The second valve 670 is controlled by the controller 610 and is selectively positionable to allow refrigerant to flow through the second valve 670. When the second valve 670 is fully closed and at least one of the economization valve 470 and the first valve 570 is open, all of the refrigerant in the secondary refrigerant loop 460 flows through the economization duct 465 and / or the first supply duct 565, and the system 1100 operates substantially similarly to the system 900 shown in FIG. 6. When the second valve 670 is fully or partially open, the gaseous or two-phase refrigerant exiting the heat exchanger 490 is separated into up to three streams: a portion of the refrigerant flows through the economization duct 465, another portion flows through the first supply duct 565, and the remainder is bypassed through the second supply duct 665. The second valve 670 may be a solenoid valve (shown in FIG. 8), an electronic expansion valve, or any type of valve that enables the system 1100 to function as described herein.

[0040] When the second valve 670 is open, the second supply duct 665 provides a second refrigerant flow to facilitate cooling of the motor 108. The second supply duct 665 is fluidly connected to the return duct 520 and combines the first and second flows to form a return flow that mixes with the refrigerant flow upstream of the compressor inlet 110.

[0041] FIG. 9 illustrates a fifth example vapor compression system 1200 in which the dynamic compressor 100 of FIGS. 1 and 2 may be installed. In addition to all of the components shown and described with respect to the fourth example vapor compression system 1100 illustrated in FIG. 8, the refrigeration equipment 560 of system 1200 further includes a third supply duct 765 fluidly connected between the heat exchanger 490 and the driver 616. The secondary refrigerant loop 460 branches downstream of the heat exchanger 490 into an economization duct 465, a first supply duct 565, a second supply duct 665, and a third supply duct 765. A portion of the refrigerant flow in the secondary refrigerant loop 460 flows through the economization duct 465, the first supply duct 565, and the second supply duct 665, as described above with respect to the fourth example vapor compression system 1100. The remainder of the refrigerant flow in the secondary refrigerant loop 460 flows through a third supply duct 765 to provide a third refrigerant flow to the drive unit 616 .

[0042] The third supply duct 765 includes a third valve 770 fluidly connected to the third supply duct 765. The third valve 770 is controlled by the controller 610 and is selectively positionable to allow refrigerant to flow through the third valve 770. When the third valve 770 is fully closed and at least one of the economization valve 470, the first valve 570, and the second valve 670 is open, all of the refrigerant in the secondary refrigerant loop 460 flows through the economization duct 465, the first supply duct 565, and / or the second supply duct 665, and the system 1200 operates substantially similarly to the system 1100 shown in FIG. When third valve 770 is fully or partially open, the gaseous or two-phase refrigerant exiting heat exchanger 490 is separated into up to four streams: some of the refrigerant flows through economization duct 465, another portion flows through first supply duct 565, another portion flows through second supply duct 665, and the remainder is bypassed through third supply duct 765. Third valve 770 may be a solenoid valve (shown in FIG. 9), an electronic expansion valve, or any type of valve that enables system 1200 to function as described herein.

[0043] When third valve 770 is open, third supply duct 765 provides a third refrigerant flow to facilitate cooling of drive unit 616. Third supply duct 765 is fluidly connected to return duct 520 and combines the first, second, and third flows to form a return flow that mixes with the refrigerant flow upstream of compressor inlet 110.

[0044] In further embodiments (not shown), the vapor compression system of the present disclosure may include any combination of an economization duct 465, a first supply duct 565, a second supply duct 665, a third supply duct 765, and a return duct 520 in any suitable configuration.

[0045] The memory 612 stores instructions that program the processor 611 to control the supply of refrigerant to the compressor 100, the motor 108, and the driver 616 based on the operating parameters of each component. Examples of control algorithms are shown in FIGS. 10-15. The processor 611 operates the dynamic compressor 100 to compress the refrigerant and the cooling equipment 560 to provide a flow of refrigerant to one or more bearing assemblies 200 of the dynamic compressor 100 through the first supply duct 565. While operating the dynamic compressor 100 and the cooling equipment 560, the processor 611 determines whether a condition is met. If the condition is met, the instructions stored in the memory 612 program the processor 611 to adjust the position of a valve in fluid communication between the dynamic compressor 100 and the cooling equipment 560.

[0046] 10 , determining whether the condition is met includes determining that the condition is met when the dynamic compressor 100 is no longer operating. In such embodiments, adjusting the valve position includes closing the first valve 570 to suspend the supply of refrigerant to the bearing assembly 200. If it is determined that the dynamic compressor 100 is still operating, the condition is determined to be not met. If it is determined that the dynamic compressor 100 is still operating, and in embodiments where the first valve 570 is a solenoid valve, the instructions stored in the memory 612 program the processor 611 to continue operating the dynamic compressor 100 with the first valve 570 open. In embodiments where the first valve 570 is an electronic expansion valve (EXV), the instructions stored in the memory 612 program the processor 611 to continue operating the dynamic compressor 100 with the first valve 570 set to a pressure setpoint. In some embodiments, the pressure setpoint P set is the suction pressure P at the inlet 110 of the dynamic compressor 100 suction and pressure offset P offset is equal to the sum of: P set =P suction +P offset Pressure offset P offset may be 1 psi, 2 psi, or other suitable pressure offset that creates a sufficient pressure difference to allow refrigerant to flow through the bearing assembly 200.

[0047] In embodiments in which the cooling equipment 560 includes a second supply duct 665 and a second valve 670 fluidly connected to the second supply duct 665, the instructions stored in the memory 612 program the processor 611 to determine whether the motor 108 is overheating based on the measured temperature of the return flow or the motor 108. For example, with reference to FIG. 11 , determining whether the motor 108 is overheating may include determining whether the return flow temperature T r and determining the temperature of the return temperature upper threshold T r,up In some embodiments, the return temperature upper threshold T r,up may be, for example, but not limited to, 130°F or 140°F. r The temperature returns to the upper temperature threshold T r,up In another embodiment, determining whether the motor 108 is overheating is performed by detecting the motor temperature T m and determining the motor temperature upper threshold T m,up In some embodiments, the motor temperature upper threshold T m,up The motor temperature T may be, for example, but not limited to, 180°F or 200°F. m is the upper limit threshold of the motor temperature T m,up If it is higher than

[0048] In either case, if the condition is met, it is determined that the motor 108 is overheating and requires cooling. Thus, adjusting the valve position in such an embodiment includes opening the second valve 670 to provide a second flow of refrigerant to the motor 108. If the condition is not determined to be met and the motor 108 is not determined to be overheating, the instructions stored in memory 612 program the processor 611 to continue operating the dynamic compressor 100 without adjusting the position of the second valve 670.

[0049] In embodiments in which the cooling device 560 includes a third supply duct 765 and a third valve fluidly connected to the third supply duct 765, the instructions stored in the memory 612 program the processor 611 to determine whether the drive unit 616 is overheating based on the temperature of the drive unit 616 measured by the drive unit temperature sensor. In such embodiments, and with reference to FIG. 12 , determining that the drive unit 616 is overheating may include determining whether the drive unit temperature T d and determining the drive temperature upper threshold T d,up In some embodiments, the drive temperature upper threshold T d,up may be, for example, but not limited to, 160°F or 180°F. d is the drive unit temperature upper limit threshold T d,up If it is greater, the condition is determined to be met.

[0050] If the condition is met, it is determined that the driver 616 is overheated and requires cooling. Thus, adjusting the valve position in such an embodiment includes opening the third valve 770 to provide a third refrigerant flow to the driver 616. If the condition is not met and it is determined that the driver 616 is not overheated, the instructions stored in the memory 612 program the processor 611 to continue operating the dynamic compressor 100 without adjusting the position of the third valve 770.

[0051] In some embodiments, the condition is a first condition, and the instructions stored in memory 612 further program the processor 611 to determine whether a second condition is met and adjust the position of the valve if the second condition is met. For example, the instructions stored in memory 612 program the processor 611 to determine whether the motor 108 and the driver 616 have sufficiently cooled after the second or third valve 670, 770 is opened.

[0052] For example, referring to FIG. 13, determining whether the motor 108 is overcooled involves determining the temperature of the return flow T r Determine the return temperature lower threshold T r,low In some embodiments, the return temperature lower threshold T r,low is the upper threshold of the return temperature T r,up and the return temperature deadband value T r,db The difference between: T r,low =T r,up -T r,db Determining whether the motor 108 is overcooled involves determining the motor temperature T m and the motor temperature lower limit threshold T m,low In some embodiments, the motor temperature lower threshold T m,low is the upper limit threshold for the motor temperature T m,up and the motor temperature dead band value T m,db The difference between: T m,low =T m,up -T m,db The motor temperature deadband may be, for example, but not limited to, 10° F. or 15° F. The second condition is the return flow temperature T r The temperature lower limit threshold T r,low and / or motor temperature T m is the motor temperature lower limit threshold T m,low If it is less than 1, it is determined to be satisfied.

[0053] In either case, if the second condition is met, it is determined that the motor 108 is sufficiently cooled and no longer requires cooling. Thus, adjusting the valve position in such an embodiment includes closing the second valve 670 to terminate the flow of the second refrigerant to the motor 108. If the second condition is not determined to be met and the motor 108 is not determined to be subcooled, the instructions stored in the memory 612 program the processor 611 to continue operating the dynamic compressor 100 with the second valve 670 open.

[0054] Similarly, referring to FIG. 14, determining whether the drive 616 is overcooled can be performed by measuring the measured drive temperature T d and determine the drive temperature lower limit threshold T d,low In some embodiments, the drive temperature lower threshold T d,low is the drive temperature upper limit threshold T d,up and the drive temperature deadband value T d,db The difference between: T d,low =T d,up -T d,db Measured drive temperature T d is the drive temperature lower limit threshold T m,low If the second condition is lower than

[0055] If the second condition is met in such an embodiment, it is determined that the driver 616 is sufficiently cooled and no longer requires cooling. Thus, adjusting the valve position in such an embodiment includes closing the third valve 770 to terminate the flow of the third refrigerant to the driver 616. If the second condition is determined not to be met and the driver 616 is not subcooled, the instructions stored in memory 612 program the processor 611 to continue operating the dynamic compressor 100 with the third valve 770 open.

[0056] 15 is a flow chart of an exemplary control algorithm for controlling the operation of the cooling device 560 when the motor 108 or drive unit 616 shown in FIGS. 11-14 is overheating or overcooling. r and / or motor temperature T m are the upper thresholds T r,up , T m,up The second valve 670 is set to open when the return flow temperature T r and motor temperature T m and each have a lower threshold T r,low , T m,low , the second valve 670 is reset to close. d is the upper threshold T d,up The third valve 770 is set to open when the driving temperature T d is the lower threshold T d,low , the third valve 770 is reset to close.

[0057] Technical advantages of the described methods and systems include the ability of a vapor compression system to provide vapor injection cooling to the dynamic compressor's bearings, motor, and drive using existing vapor paths from an economization system. Furthermore, the dynamic compressor's bearings, motor, and drive can be cooled using vapor injection without risk of liquid flooding the bearings or compressor flowpaths. Steam injection is also suitable for the small amounts of cooling required for bearings.

[0058] As used herein, the terms "about," "substantially," "essentially," and "approximately," when used in conjunction with a range of dimensions, concentrations, temperatures, or other physical or chemical properties or characteristics, are intended to include variations that may exist at the upper and / or lower limits of the range of the property or characteristic, such as variations resulting from rounding, measurement method, or other statistical variations.

[0059] When introducing elements of the present disclosure or embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," "containing," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of specific orientation terms (such as "top," "bottom," and "side") is for convenience of description and does not require a particular orientation of the described items.

[0060] Because various changes may be made in the above structures and methods without departing from the scope of this disclosure, it is intended that all matter contained in the above description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.

Claims

1. 1. A vapor compression system, comprising: a primary loop and a secondary loop; The primary loop a dynamic compressor operable to compress a refrigerant, the dynamic compressor including a housing, a shaft supported by bearings within the housing, and an impeller connected to the shaft; a motor operatively connected to the shaft for driving rotation of the shaft; a drive unit operable to control the motor; a condenser fluidly connected to the dynamic compressor; a first expansion device fluidly connected to the condenser; an evaporator fluidly connected to the first expansion device and the dynamic compressor; The secondary loop a second expansion device fluidly connected to the condenser; a heat exchanger fluidly connected to the second expansion device, the condenser, and the dynamic compressor; a supply duct fluidly connected between the heat exchanger and the dynamic compressor for supplying a flow of refrigerant to the bearing. Vapor compression system.

2. 10. The vapor compression system of claim 1, wherein the supply duct includes a valve operable to control the flow of refrigerant therethrough.

3. 10. The vapor compression system of claim 1, wherein the heat exchanger is a flash tank.

4. 2. The vapor compression system of claim 1, wherein the secondary loop further includes a return duct fluidly connecting the supply duct to the dynamic compressor for providing a return flow of refrigerant thereto.

5. 10. The vapor compression system of claim 1, wherein the supply duct is a first supply duct, the refrigerant flow is a first refrigerant flow, and the secondary loop further includes a second supply duct fluidly connecting the heat exchanger to the motor and supplying a second refrigerant flow to the motor.

6. 6. The vapor compression system of claim 5, wherein the secondary loop further includes a third supply duct fluidly connecting the heat exchanger to the drive device for supplying a third refrigerant flow thereto.

7. 7. The vapor compression system of claim 6, wherein the secondary loop further includes a return duct fluidly connecting the first, second, and third supply ducts to the dynamic compressor for supplying a return flow of refrigerant to the dynamic compressor.

8. 2. The vapor compression system of claim 1, wherein the secondary loop further includes an economization duct fluidly connecting the heat exchanger to the dynamic compressor for providing an economized stream of refrigerant to the dynamic compressor between a first stage and a second stage.

9. 1. A controller for a compressor system including a dynamic compressor and a refrigeration device, comprising: the cooling equipment includes a heat exchanger and a supply duct fluidly connected between the heat exchanger and the dynamic compressor; The controller a processor; a memory, The memory includes: operating the dynamic compressor to compress a refrigerant; operating the refrigeration equipment to supply a flow of refrigerant through the supply duct to a bearing of the dynamic compressor; Determining whether a condition is met, and and if the condition is met, adjusting a position of a valve in fluid communication between the dynamic compressor and the refrigeration equipment. controller.

10. 10. The controller of claim 9, wherein the valve is a first valve fluidly connected to the supply duct between the heat exchanger and at least one of the bearings, and wherein determining whether the condition is met includes determining that the condition is met when the dynamic compressor is no longer operating, and wherein adjusting a valve position includes closing the first valve.

11. 10. The controller of claim 9, wherein the supply duct is a first supply duct, the refrigerant flow is a first refrigerant flow, and the cooling equipment further includes a second supply duct for fluidly connecting the heat exchanger to a motor operably connected to the dynamic compressor, the second supply duct supplying a second refrigerant flow to the motor.

12. 12. The controller of claim 11, wherein the cooling equipment further includes: a second valve fluidly connected to the second supply duct between the heat exchanger and the motor; a return duct fluidly connecting the first and second supply ducts to the dynamic compressor to provide a return flow of refrigerant to the dynamic compressor; and a return temperature sensor operable to measure a temperature of the return flow, wherein determining whether the condition is met includes determining that the condition is met if the temperature of the return flow is greater than a return temperature upper threshold, and adjusting the position of the valve includes opening the second valve.

13. 12. The controller of claim 11, wherein the motor includes a motor temperature sensor operable to measure a temperature of the motor, and wherein determining whether the condition is met includes determining that the condition is met if the temperature of the motor is greater than a motor temperature upper threshold, and wherein adjusting the position of the valve includes opening a second valve fluidly connected to the second supply duct between the heat exchanger and the motor.

14. 12. The controller of claim 11, wherein the cooling equipment further includes a third supply duct for fluidly connecting the heat exchanger to a drive device operable to control the motor, the third supply duct supplying a third refrigerant flow to the drive device.

15. 15. The controller of claim 14, wherein the drive unit includes a drive unit temperature sensor operable to measure a temperature of the drive unit, and wherein determining whether the condition is met includes determining that the condition is met if the temperature of the drive unit is greater than a drive unit temperature upper threshold, and wherein adjusting the position of the valve includes opening a third valve fluidly connected to the third supply duct between the heat exchanger and the drive unit.

16. The condition is a first condition, and the memory stores: determining whether a second condition is met; and 10. The controller of claim 9, further comprising instructions that program the processor to: adjust a position of the valve if the second condition is met.

17. the supply duct is a first supply duct, the refrigerant flow is a first refrigerant flow, and the cooling device is a second supply duct for supplying a second refrigerant flow from the heat exchanger to a motor operatively connected to the dynamic compressor; a second valve fluidly connected to the second supply duct; a return duct for supplying a return flow of refrigerant from the first and second supply ducts to the dynamic compressor; a return temperature sensor operable to measure the temperature of the return flow; determining whether the second condition is satisfied includes determining that the second condition is satisfied if the temperature of the return flow is less than a lower return temperature threshold; The controller of claim 16 , wherein adjusting the position of the valve includes closing the second valve.

18. the supply duct is a first supply duct, the refrigerant flow is a first refrigerant flow, and the cooling device is a second supply duct for supplying a second refrigerant flow from the heat exchanger to a motor operatively connected to the dynamic compressor; a second valve fluidly connected to the second supply duct; a return duct for supplying a return flow of refrigerant from the first and second supply ducts to the dynamic compressor; a motor temperature sensor operable to measure a temperature of the motor; determining whether the second condition is satisfied includes determining that the second condition is satisfied if the temperature of the motor is less than a lower motor temperature threshold; The controller of claim 16 , wherein adjusting the position of the valve includes closing the second valve.

19. the supply duct is a first supply duct, the refrigerant flow is a first refrigerant flow, and the cooling device is a third supply duct for supplying a third refrigerant flow from the heat exchanger to a drive device operable to control a motor operably connected to the dynamic compressor; a third valve fluidly connected to the third supply duct; a drive temperature sensor operable to measure a temperature of the drive; determining whether the second condition is satisfied includes determining that the second condition is satisfied if the temperature of the drive device is less than a drive device temperature lower threshold; The controller of claim 16 , wherein adjusting the position of the valve includes closing the third valve.

20. 1. A compression system, comprising: a dynamic compressor operable to compress a refrigerant; and a refrigeration device; The dynamic compressor comprises: housing, a shaft supported within the housing by bearings; and an impeller connected to the shaft; The cooling device includes: a heat exchanger fluidly connected to the dynamic compressor; a supply duct fluidly connected between the heat exchanger and the dynamic compressor for supplying a flow of refrigerant to the bearing; a valve fluidly connected to the supply duct, the valve being selectively positionable to allow refrigerant to flow therethrough; a controller operable to control the valve; Compression system.

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