CN110582647A

CN110582647A - Variable geometry diffuser ring

Info

Publication number: CN110582647A
Application number: CN201880029566.3A
Authority: CN
Inventors: 保罗·W·斯內尔
Original assignee: Johnson Controls Technology Co
Current assignee: Johnson Controls Technology Co
Priority date: 2017-03-09
Filing date: 2018-03-08
Publication date: 2019-12-17
Also published as: KR20210045512A; WO2018165474A1; KR20190121382A; TW201839331A; JP2020510786A; EP3592984A1; US20200018326A1

Abstract

A compressor includes: an impeller; a diffuser channel having diffuser vanes therein; and a variable geometry diffuser ring positioned between the impeller and the diffuser vanes with respect to a flow of refrigerant through the compressor. The compressor also includes an actuator configured to move the variable geometry diffuser ring in a direction transverse to a flow of the refrigerant and between a plurality of ring positions including a ring fully retracted position in which the variable geometry diffuser ring does not block the flow of the refrigerant and at least one ring protruding position in which the variable geometry diffuser ring adjusts a flow angle of the refrigerant upstream of the diffuser vanes.

Description

variable geometry diffuser ring

Background

the present application relates generally to vapor compression systems incorporated in air conditioning and refrigeration applications, and more particularly to flow control of refrigerant in a compressor.

Vapor compression systems are used in residential, commercial, and industrial environments to control environmental characteristics, such as temperature and humidity, of occupants of the respective environments. Vapor compression systems circulate a working fluid, typically referred to as a refrigerant, that changes phase between vapor, liquid, and combinations thereof in response to different temperatures and pressures associated with operation of the vapor compression system. For example, vapor compression systems utilize a compressor to circulate a refrigerant to a heat exchanger, which can transfer heat between the refrigerant and another fluid flowing through the heat exchanger. Conventional compressors may operate most efficiently when operating at full displacement, but may be configured to operate at different displacements based on different operating and environmental conditions. In other words, at certain operating displacements, the efficiency of the conventional compressor may be reduced.

disclosure of Invention

In one embodiment, a compressor includes: an impeller; a diffuser channel having diffuser vanes therein; and a variable geometry diffuser ring positioned between the impeller and the diffuser vanes with respect to a flow of refrigerant through the compressor. The compressor also includes an actuator configured to move the variable geometry diffuser ring in a direction transverse to a flow of the refrigerant and between a plurality of ring positions including a ring fully retracted position in which the variable geometry diffuser ring does not block the flow of the refrigerant and at least one ring protruding position in which the variable geometry diffuser ring adjusts a flow angle of the refrigerant upstream of the diffuser vanes.

In another embodiment, a heating, ventilation, air conditioning and refrigeration (HVAC & R) system includes a compressor having diffuser vanes and having a variable geometry diffuser ring positioned upstream of the diffuser vanes with respect to a flow of refrigerant therethrough. The system also includes a controller configured to control a position of the variable geometry diffuser ring based at least in part on an operating displacement of the compressor and based at least in part on an angle of attack of a leading edge of the diffuser vanes.

In another embodiment, a method of operating a compressor includes: detecting the temperature of the refrigerant; and determining, via a controller, an operating displacement of the compressor based at least in part on the temperature of the refrigerant. The method also includes controlling a position of a variable geometry diffuser ring based at least in part on an operating displacement of the compressor and based at least in part on an angle of attack of a leading edge of a diffuser vane of the compressor.

Drawings

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

FIG. 2 is a perspective view of a vapor compression system according to one aspect of the present disclosure;

FIG. 3 is a schematic view of an embodiment of the vapor compression system of FIG. 2, according to an aspect of the present disclosure;

FIG. 4 is a schematic view of an embodiment of the vapor compression system of FIG. 2, according to an aspect of the present disclosure;

FIG. 5 is a cross-section of an embodiment of a portion of a compressor that may be included in the system of FIGS. 1-4, according to an aspect of the present disclosure;

FIG. 6 is a cross-section of a portion of the compressor of FIG. 5 taken along line 6-6 in FIG. 5 in accordance with an aspect of the present disclosure;

FIG. 7 is a cross-section of an embodiment of a portion of a variable geometry diffuser ring for use in the compressor of FIG. 5, in accordance with an aspect of the present disclosure;

FIG. 8 is a cross-section of an embodiment of a portion of a variable geometry diffuser ring for use in the compressor of FIG. 5, in accordance with an aspect of the present disclosure;

FIG. 9 is a cross-section of an embodiment of a portion of a variable geometry diffuser ring for use in the compressor of FIG. 5, in accordance with an aspect of the present disclosure;

FIG. 10 is a cross-section of an embodiment of a variable geometry diffuser ring positioned in a portion of the compressor of FIG. 5 in accordance with an aspect of the present disclosure; and is

FIG. 11 is a block diagram illustrating an embodiment of a method of operating a compressor in accordance with an aspect of the present disclosure.

Detailed Description

One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

embodiments of the present disclosure relate to a heating, ventilation, air conditioning and refrigeration (HVAC & R) system that uses a compressor (e.g., a centrifugal compressor) to circulate refrigerant through a refrigerant circuit. The compressor may be configured to convert kinetic energy of the refrigerant flow into pressure. Unfortunately, conventional compressors may be designed to operate primarily at a certain amount of load (e.g., full load and at full displacement). For example, the flow angle of the refrigerant at different locations in the compressor may be a function of the operating displacement of the compressor, and the efficiency of the compressor (and certain components thereof) may depend on the flow angle of the refrigerant. As a result, conventional compressors may be inefficient when operating at a displacement that deviates from the primary operating mode (e.g., full displacement).

According to the present embodiment, a compressor of an HVAC & R system may include a variable geometry diffuser ring located between a rotatable impeller of the compressor and diffuser blades of the compressor. For example, the compressor may receive refrigerant at an inlet and may deliver the refrigerant to the impeller. The impeller includes blades that are angled with respect to the flow of refrigerant. The blades of the rotatable impeller accelerate the refrigerant outwardly from the center of rotation of the impeller. The accelerated refrigerant may be directed towards a diffuser designed to convert the kinetic energy of the refrigerant flow into pressure, for example by gradually reducing the flow velocity of the refrigerant. As described above, the diffuser may include fixed diffuser vanes that are angled, positioned, or otherwise oriented to improve the efficiency of kinetic energy conversion to pressure. However, since the diffuser vanes are fixed, the angle of attack of the leading edge of each diffuser vane is also fixed. Further, as noted above, the flow angle of the refrigerant may change as the load of the compressor changes. The angle of attack of the leading edge of the diffuser blade(s) may enable kinetic energy to be most efficiently converted to pressure at a particular operating displacement (e.g., full displacement) of the compressor. Thus, according to the present disclosure and as described below, a variable geometry diffuser ring may be used to adjust the flow angle of the refrigerant to correspond to the angle of attack of the diffuser vanes, which improves the efficiency of the diffuser vanes and the compressor.

For example, a variable geometry diffuser ring may be positioned between the impeller and the diffuser vane(s), and the variable geometry diffuser ring may be configured to adjust the flow angle of the refrigerant passing therethrough such that the flow angle of the refrigerant corresponds to the angle of attack of the diffuser vane(s). As noted below with reference to the figures, a control system of the HVAC & R system may adjust the position of the variable geometry diffuser ring based on the operating load/displacement of the compressor (e.g., via an actuator coupled between the variable geometry diffuser ring and a controller) such that the variable geometry diffuser ring adjusts the flow angle of the refrigerant passing to the diffuser vanes. In doing so, the efficiency of the compressor is increased over the conventional embodiment at different operating loads/displacements.

Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, air conditioning and refrigeration (HVAC & R) system 10 in a building 12 for a typical commercial setting. The HVAC & R system 10 may include a vapor compression system 14 that supplies a chilled liquid that may be used to cool the building 12. The HVAC & R system 10 may also include a boiler 16 for supplying a 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 connected to the boiler 16 and the vapor compression system 14 by a conduit 24. The heat exchanger in the air handler 22 may receive heated liquid from the boiler 16 or chilled liquid from the vapor compression system 14, depending on the mode of operation of the HVAC & R system 10. The HVAC & R system 10 is shown with a separate air handler on each floor of the building 12, but in other embodiments the HVAC & R system 10 may include an air handler 22 and/or other components that are sharable between two or more floors.

Fig. 2 and 3 are embodiments of a vapor compression system 14 that may be used in the HVAC & R system 10. The vapor compression system 14 may circulate refrigerant through a circuit beginning with a compressor 32. The circuit may also include a condenser 34, expansion valve(s) or expansion device(s) 36, and a liquid chiller or evaporator 38. 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.

Some examples of fluids that may be used as the refrigerant in the vapor compression system 14 are Hydrofluorocarbon (HFC) -based refrigerants (e.g., R-410A, R-407, R-134a), Hydrofluoroolefins (HFO), "natural" refrigerants (such as ammonia (NH), for example₃) R-717, carbon dioxide (CO)₂) R-744), or a hydrocarbon based refrigerant, water vapor, or any other suitable refrigerant. In some embodiments, the vapor compression system 14 may be configuredIs configured to efficiently utilize a refrigerant having a normal boiling point of about 19 degrees celsius (66 degrees fahrenheit) at one atmosphere (relative to an intermediate pressure refrigerant such as R-134a, also referred to as a low pressure refrigerant). As used herein, "normal boiling point" may refer to the boiling point temperature measured at one atmosphere of pressure.

in some embodiments, the vapor compression system 14 may use one or more of the following: 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 motor 50 may drive the compressor 32 and may be powered by a Variable Speed Drive (VSD) 52. VSD 52 receives Alternating Current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source and provides power having a variable voltage and frequency to motor 50. In other embodiments, the motor 50 may be powered directly by an AC power source or a Direct Current (DC) power source. The motor 50 may include any type of motor that may be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

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

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

Fig. 4 is a schematic diagram of the vapor compression system 14 with an intermediate circuit 64 coupled between the condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line 68 fluidly connected directly to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly connected to the condenser 34. As shown in the illustrated embodiment of fig. 4, inlet line 68 includes a first expansion device 66 located upstream of an intermediate vessel 70. In some embodiments, the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate vessel 70 may be configured as a heat exchanger or "surface economizer". In the embodiment illustrated in fig. 4, the intermediate vessel 70 functions as a flash tank, and the first expansion device 66 is configured to reduce the pressure (e.g., expand) of the liquid refrigerant received from the condenser 34. During the expansion process, a portion of the liquid may vaporize, and thus the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66. In addition, the intermediate container 70 may provide further expansion of the liquid refrigerant due to a pressure drop experienced by the liquid refrigerant upon entering the intermediate container 70 (e.g., due to a rapid increase in volume experienced upon entering the intermediate container 70). Vapor in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32. In other embodiments, the vapor in the intermediate container may be drawn to 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 liquid collected in the intermediate container 70 may be at a lower enthalpy than the liquid refrigerant exiting the condenser 34. Liquid from the intermediate vessel 70 may then flow into line 72 through the second expansion device 36 to the evaporator 38.

as noted above, according to the present embodiment, the compressor 32 illustrated in fig. 2-4 (which may be included in the system of fig. 1) may include a variable geometry diffuser ring configured to increase the efficiency of the compressor 32. For example, a variable geometry diffuser ring is positioned to adjust the flow angle through which refrigerant passes. In particular, the variable geometry diffuser collar adjusts the flow angle of the refrigerant such that the flow angle corresponds to (e.g., conforms to, matches, corresponds to, fits) the angle of attack of the leading edge of one or more diffuser vanes that receive the refrigerant downstream of the variable geometry diffuser collar.

For example, the position of the variable geometry diffuser ring may be commanded or controlled by a control system that determines a desired position of the variable geometry diffuser ring based on the operating displacement of the compressor 32. As a non-limiting example, the control system may instruct the variable geometry diffuser ring (via an intermediate actuator, in some embodiments) to move to its retracted position when the compressor 32 is operating at full displacement, such that the flow path of the refrigerant to the diffuser vanes is not blocked by the variable geometry diffuser ring. The control system may instruct the variable geometry diffuser ring to move to another position of the variable geometry diffuser ring that partially obstructs the flow path when the compressor 32 is operating, for example, at 75% displacement. The control system may instruct/control the variable geometry diffuser ring to move to yet another position of the variable geometry diffuser ring that further blocks the flow path when the compressor 32 is operating, for example, at 50% displacement. Thus, as the operating displacement or load of the compressor 32 decreases, the amount of blockage of the flow path determined by the position of the variable geometry diffuser ring increases. In so doing, the flow angle of the refrigerant is caused to correspond to (e.g., coincide with) the angle of attack of the leading edge of the one or more diffuser vanes. These and other features will be described in detail with reference to the following drawings.

Fig. 5 is a cross-section of an embodiment of a portion of the compressor 32 that may be included in any of fig. 1-4. A refrigerant flow 99 is illustrated through the compressor 32, wherein the refrigerant flow 99 extends over blades 102 of an impeller 100 of the compressor 32, towards a diffuser passage 103 having one or more diffuser blades 104 disposed therein, and into an accumulator 106. It should be noted that the illustrated refrigerant flow 99 is indicative of the general flow direction, but should not be considered as indicative of the exact flow angle at any particular location of the compressor 32.

The blades 102 of the rotating impeller 100 accelerate the refrigerant outward from the center of rotation of the impeller 100. The accelerated refrigerant may travel along the demonstrated refrigerant path 99 towards a diffuser channel 103 designed to convert the kinetic energy of the refrigerant flow 99 into pressure, for example by gradually reducing the velocity of the refrigerant flow 99. As described above, the diffuser vanes 104 may be fixed and may be angled, positioned, or otherwise oriented to enhance the kinetic energy to pressure conversion of the refrigerant flow 99. Generally, the diffuser vanes 104 may each include a leading edge 105 that is angled to improve the efficiency of the compressor 32 at a particular operating displacement (e.g., full displacement) when the diffuser passage 103 is not blocked by the variable geometry diffuser ring 108, as will be described in detail below. The accumulator 106 of the compressor 32 receives pressurized refrigerant for distribution to downstream chiller components.

As noted above, the compressor 32 may include a variable geometry diffuser ring 108 disposed in or proximate to a lower portion of the diffuser passage 103 (e.g., between the impeller 100 and the diffuser vanes 104). The variable geometry diffuser ring 108 includes adaptable positions configured to enhance the efficiency of the diffuser vanes 104 and, more generally, the compressor 32. For example, the variable geometry diffuser ring 108 may be coupled to an actuator 112 that actuates or moves the variable geometry diffuser ring 108 from a previous position to a desired position as directed by a controller 114. The controller 114 may control the position of the variable geometry diffuser ring 108 such that the variable geometry diffuser ring 108 adjusts the flow angle of the refrigerant flow 99 to correspond to the operating displacement of the compressor 32, as will be described in detail below.

the controller 114 may include a processor 116 and a memory 118, where the memory 118 includes instructions stored thereon that, when executed by the processor 116, cause the controller 114 to perform certain actions. For example, the controller 114 may control the operating displacement of the compressor 32 based at least in part on certain operating and/or environmental conditions (e.g., refrigerant temperature). The controller 114 may also include data stored in the memory 118 that indicates a desired position of the variable geometry diffuser ring 108 based on an operating displacement of the compressor 32. Thus, when the controller 114 controls the operating displacement of the compressor 32, the controller 114 may also control the position of the variable geometry diffuser ring 108, which will cause the flow angle of the refrigerant flow 99 to correspond to the angle of attack of the leading edge 105 of the diffuser vane(s) 104. In one example, at full operating displacement, the controller 114 may instruct the variable geometry diffuser ring 108 to move to a fully retracted position of the variable geometry diffuser ring 108 (e.g., into a cavity of the sidewall 109 adjacent to the diffuser passage 103 of the compressor 32) such that the variable geometry diffuser ring 108 does not block the refrigerant flow 99. At 50% operating displacement, the controller 114 may control the variable geometry diffuser collar 108 to move to a position that protrudes the variable geometry diffuser collar 108 into the refrigerant flow 99 (e.g., in the diffuser passage 103). For example, fig. 6 is a cross-section of a portion of the compressor 32 of fig. 5 with the variable geometry diffuser ring 108 in a partially blocking position. As shown in fig. 5 and 6, the variable geometry diffuser ring 108 is generally configured to travel along a direction 110, and as shown in fig. 6, may restrict a portion of the diffuser passage 103 to a smaller width 114 as compared to the overall width 115 of the unobstructed portion of the diffuser passage 103.

In fig. 5 and 6, the variable geometry diffuser ring 108 comprises a rectangular cross-section. In fig. 6, the projecting surface 116 of the variable geometry diffuser ring 108 forms the short side of the rectangular shape and the sliding surface 118 of the variable geometry diffuser ring 108 forms the long side of the rectangular shape. However, in another embodiment, the sliding surface 118 may form the short side of the rectangular shape and the protruding surface 116 may form the long side of the rectangular shape.

The variable geometry diffuser ring 108 may include shapes other than the rectangular shapes shown in fig. 5 and 6. For example, fig. 7, 8, and 9 are cross-sections of embodiments of portions of a variable geometry diffuser ring 108 for use in the compressor 32 of fig. 5. Fig. 7 includes a square or rectangular cross-section similar to fig. 5 and 6. In fig. 8, the variable geometry diffuser ring 108 includes a sharp protruding surface 116. In other words, the variable geometry diffuser ring 108 is triangular or includes triangular portions. In fig. 9, the variable geometry diffuser ring 108 includes a curved protruding surface 116. The curvature may form a semi-circle, a semi-oval, a semi-ellipse, or some other curved surface. The shape of the projecting surface 116 of the variable geometry diffuser ring 108 may be selected based on the geometric or operational characteristics of the particular compressor 32 in which the variable geometry diffuser ring 108 is disposed.

additionally or alternatively, the variable geometry diffuser ring 108 may include an L-shape. For example, FIG. 10 is a cross-section of an embodiment of a variable geometry diffuser ring 108 located in a portion of the compressor 32 of FIG. 5. In the illustrated embodiment, the projecting surface 116 and the sliding surface 119 of the variable geometry diffuser ring 108 form a portion of a leg 120 of the variable geometry diffuser ring 108 that extends from a base 122 of the variable geometry diffuser ring 108. As shown, the legs 120 and the base 122 form an L-shape. The L-shaped base 122 may be disposed in a cavity 124 adapted to receive the base 122 and to allow the base 122 to move within the cavity 124 (e.g., as the legs 120 extend into and out of the diffuser passage 103).

FIG. 11 is a block diagram illustrating an embodiment of a method 200 of operating a compressor having diffuser vanes and a variable geometry diffuser ring. In the illustrated embodiment, the method 200 includes detecting (block 201) a refrigerant temperature. For example, the controller may be communicatively coupled with a temperature sensor that provides data indicative of the refrigerant temperature to the controller. As previously described, in some embodiments, the refrigerant may be water.

the method 200 also includes determining (block 202) an operating displacement or load of the compressor. For example, based on the refrigerant temperature and/or other characteristics described above, the controller may determine an appropriate operating displacement of the compressor. The controller may then determine and control the compressor to load or unload to meet the appropriate operating displacement.

The method 200 also includes controlling (block 204) a position of the variable geometry diffuser ring based on an operating displacement of the compressor. For example, as noted above, an actuator (e.g., a motor-driven actuator) may be coupled to the variable geometry diffuser ring and may be communicatively coupled to the controller. The controller may instruct or control the actuator to move the variable geometry diffuser ring from one position to another based on a change in an operating displacement of the compressor. As described below, the actuator may then move (block 206) the variable geometry diffuser collar into position such that the variable geometry diffuser collar adjusts the flow angle of the refrigerant to correspond to the angle of attack of the leading edge of the diffuser vane.

Generally, when operating at full displacement, the controller may instruct the actuator to move the variable geometry diffuser ring to a fully retracted position (e.g., a position within a cavity of a sidewall of the compressor), wherein the variable geometry diffuser ring does not adjust a flow angle of refrigerant received from an impeller of the compressor. When operating at less than full displacement, the controller may instruct the variable geometry diffuser collar to move to a protruding position, wherein the variable geometry diffuser collar is positioned in a flow path of the refrigerant (e.g., between the impeller and the diffuser vanes) such that the variable geometry diffuser collar adjusts a flow angle of the refrigerant to correspond to an angle of attack of the diffuser vanes. In other words, when operating at less than full displacement, the flow angle of the refrigerant may be different from the angle of attack of the leading edge of the diffuser vane in the absence of the variable geometry diffuser ring, which reduces the efficiency of the diffuser vane in converting the kinetic energy of the refrigerant to pressure. By selectively positioning the variable geometry diffuser ring based on the% displacement of the compressor, the flow angle of the refrigerant is corrected to correspond to the angle of attack of the leading edge of the diffuser vanes.

As described above, the present disclosure may provide one or more technical effects useful for increasing the efficiency of a compressor of an HVAC & R system, and more particularly for increasing the efficiency of diffuser vanes of a compressor by utilizing a variable geometry diffuser ring. The variable geometry diffuser ring is positioned to adjust a flow angle of the refrigerant to correspond to an angle of attack of a leading edge of the diffuser vane based on an indication of the controller. In some embodiments, the variable geometry diffuser ring is in a fully retracted position without modulation of the flow angle when the compressor is operating at full displacement. By selectively positioning the variable geometry diffuser ring to ensure proper flow angles of refrigerant approaching the diffuser vanes, the efficiency of the diffuser vanes (and compressor) at different operating displacements is enhanced. The technical effects and technical problems in the present specification are exemplary and not restrictive. It should be noted that the embodiments described in the specification may have other technical effects and may solve other technical problems.

Although only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), 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 varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are not intended to cover all such modifications and changes as fall within the true spirit of the disclosure. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the disclosure, or those unrelated to enabling the claimed disclosure). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.

Claims

1. a compressor, comprising:

An impeller;

a diffuser channel including diffuser vanes therein;

A variable geometry diffuser ring positioned between the impeller and the diffuser vanes relative to a flow of refrigerant through the compressor; and

An actuator configured to move the variable geometry diffuser ring in a direction transverse to a flow of the refrigerant and between a plurality of ring positions including a ring fully retracted position in which the variable geometry diffuser ring does not block the flow of the refrigerant and at least one ring protruding position in which the variable geometry diffuser ring adjusts a flow angle of the refrigerant upstream of the diffuser vanes.

2. The compressor of claim 1, comprising a controller configured to instruct the actuator to move the variable geometry diffuser ring between the plurality of positions based at least in part on an operating displacement of the compressor, a temperature of the refrigerant, or both.

3. the compressor of claim 1, comprising a controller configured to instruct said actuator to move said variable geometry diffuser ring between said plurality of ring positions based at least in part on an angle of attack of a leading edge of said diffuser vane.

4. The compressor of claim 3, wherein said controller is configured to instruct said actuator to move said variable geometry diffuser ring such that a flow angle of said refrigerant proximate said diffuser vanes corresponds to an angle of attack of leading edges of said diffuser vanes.

5. The compressor of claim 1, wherein said actuator is a motor-driven actuator.

6. The compressor of claim 1, wherein said diffuser vanes are fixed.

7. The compressor of claim 1, wherein said variable geometry diffuser ring comprises a rectangular cross-sectional shape.

8. The compressor of claim 1, wherein said variable geometry diffuser ring includes at least a portion having a triangular cross-sectional shape, a curvilinear cross-sectional shape, or an L-shaped cross-sectional shape.

9. The compressor of claim 1, comprising an accumulator positioned downstream of said diffuser passage and configured to receive said refrigerant after it is pressurized by said diffuser vanes.

10. The compressor of claim 1, wherein said variable geometry diffuser ring is positioned within said diffuser passage.

11. a heating, ventilation, air conditioning and refrigeration (HVAC & R) system comprising:

a compressor including diffuser vanes and having a variable geometry diffuser ring positioned upstream of the diffuser vanes with respect to flow of refrigerant therethrough; and

A controller configured to control a position of the variable geometry diffuser ring based at least in part on an operating displacement of the compressor and based at least in part on an angle of attack of a leading edge of the diffuser vanes.

12. The system of claim 11, wherein the diffuser vanes are fixed.

13. the system of claim 11, comprising an actuator coupled with the variable geometry diffuser collar, wherein the controller is configured to control a position of the variable geometry diffuser collar by instructing the actuator to move the variable geometry diffuser into position.

14. The system of claim 13, wherein the actuator is a motor-driven actuator.

15. The system of claim 11, wherein the controller is configured to control the variable geometry diffuser ring to move the variable geometry diffuser ring to at least one protruding position corresponding to less than full displacement operation of the compressor, wherein the variable geometry diffuser ring is disposed in the diffuser channel in the at least one protruding position, wherein the controller is configured to control the variable geometry diffuser collar to move the variable geometry diffuser collar to a fully retracted position of the variable geometry diffuser collar, the fully retracted position corresponding to the compressor full displacement operation, and wherein the variable geometry diffuser ring is not disposed in the diffuser passage in the fully retracted position.

16. The system of claim 11, wherein the variable geometry diffuser ring comprises a rectangular cross-sectional shape.

17. The system of claim 11, comprising an accumulator positioned downstream of the diffuser passage and configured to receive the refrigerant after the refrigerant is pressurized by the diffuser vanes.

18. A method of operating a compressor comprising:

Detecting the temperature of the refrigerant;

Determining, via a controller, an operating displacement of the compressor based at least in part on a temperature of the refrigerant; and

Controlling a position of a variable geometry diffuser ring based at least in part on an operating displacement of the compressor and based at least in part on an angle of attack of a leading edge of a diffuser vane of the compressor.

19. the method of claim 18, comprising actuating, via an actuator, the variable geometry diffuser ring from a previous position to the position based on a change in an operating displacement of the compressor.

20. The method of claim 18, comprising determining an operating displacement of the compressor to be full displacement and indicating a position of the variable geometry diffuser ring such that the variable geometry diffuser ring is fully retracted from a flow path of the refrigerant.