Vaned diffuser for a mixed flow compressor

Abstract

A screw compressor includes an impeller to rotate about an axis and configured to receive a working fluid directed into the impeller along the axis. The screw compressor also includes a diffuser positioned downstream of the impeller, where the diffuser may receive the working fluid from the impeller. The diffuser includes a plurality of first vanes, where the plurality of first vanes defines a plurality of first vane passages, and each first vane passage of the plurality of first vane passages may receive the working fluid. The diffuser also includes a plurality of second vanes, where each second vane of the plurality of second vanes is positioned within a respective first vane passage of the plurality of first vane passages. Each first vane includes a first arc length, each second vane includes a second arc length, and the first arc length is greater than the second arc length.

Description

VANED DIFFUSER FOR A MIXED FLOW COMPRESSORCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application Serial No. 63 / 634,266, entitled “VANED DIFFUSER FOR A MIXED FLOW COMPRESSOR,” filed April 15, 2024, which is incorporated herein by reference in its entirety for all purposes.BACKGROUND

[0002] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0003] Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems, such as chiller systems (e.g., vapor compression systems), utilize a working fluid (e.g., a refrigerant) that changes phases between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures within components of the chiller system. HVAC&R systems may include a compressor for circulating a working fluid (e.g., refrigerant) along a working fluid circuit and through heat exchangers of the HVAC&R system. For example, the HVAC&R system may include a heat exchanger configured to receive the working fluid and a conditioning fluid to place the working fluid in the heat exchange relationship with the conditioning fluid. The conditioning fluid may be directed from the heat exchanger to other equipment, such as air handlers, to condition other fluids, such as air, in a building.

[0004] Various types of compressors may be incorporated with the HVAC&R system. For example, the compressor may be a screw compressor, a centrifugal compressor, a scroll compressor, an axial compressor, a reciprocating compressor, or any other suitable type ofcompressor. Unfortunately, compressors may be susceptible to various inefficiencies. For example, fluid flow through existing compressors may experience flow losses, flow separation, fluidic restrictions, and / or other drawbacks that may contribute to inefficient operation of the compressor. Accordingly, compressors configured to be utilized in HVAC&R systems and operate with improved efficiency are desired.SUMMARY

[0005] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0006] In an embodiment, a screw compressor for a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system includes an impeller configured to rotate about an axis and configured to receive a working fluid directed into the impeller along the axis. The impeller may increase a velocity of the working fluid. The screw compressor also includes a diffuser positioned downstream of the impeller, where the diffuser is configured to receive the working fluid from the impeller. The diffuser includes a plurality of first vanes, where the plurality of first vanes defines a plurality of first vane passages, and each first vane passage of the plurality of first vane passages is configured to receive the working fluid. The diffuser also includes a plurality of second vanes, where each second vane of the plurality of second vanes is positioned within a respective first vane passage of the plurality of first vane passages. Each first vane of the plurality of first vanes includes a first arc length, each second vane of the plurality of second vanes includes a second arc length, and the first arc length is greater than the second arc length.

[0007] In another embodiment, a diffuser for a screw compressor for a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system, includes a hub, a shroud, and a plurality of first vanes extending between the hub and the shroud, where the plurality of first vanes, the hub, and the shroud define a plurality of first vane passages, and each first vane passage of the plurality of first vane passages is configured to receive a flowof working fluid. The diffuser also includes a plurality of second vanes extending between the hub and the shroud, where a second vane of the plurality of second vanes is positioned within a respective first vane passage of the plurality of first vane passages, and where the second vane of the plurality of second vanes and a first vane of the respective first vane passage define a second vane passage configured to discharge the flow of working fluid at least partially across one or more motor components of the screw compressor. Each first vane of the plurality of first vanes includes a first arc length and each second vane of the plurality of second vanes includes a second arc length, and the first arc length is greater than the second arc length.

[0008] In another embodiment, a screw compressor for a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system includes an intake portion, including an impeller configured to rotate about an axis and configured to receive a flow of working fluid directed into the impeller along the axis, where the impeller is configured to increase a velocity of the flow of working fluid. The intake portion also includes a diffuser coupled to and positioned downstream of the impeller, where the diffuser is configured to receive the flow of working fluid from the impeller. The diffuser includes a plurality of first vanes, where the plurality of first vanes defines a plurality of first vane passages, and each first vane passage of the plurality of first vane passages is configured to receive the flow of working fluid. The diffuser also includes a plurality of second vanes, where a second vane of the plurality of second vanes is positioned within a respective first vane passage of the plurality of first vane passages. Each first vane of the plurality of first vanes includes a first arc length and each second vane of the plurality of second vanes includes a second arc length, and the first arc length is greater than the second arc length. The screw compressor also includes a motor portion positioned downstream of the intake portion, where at least one motor component of the motor portion is configured to receive the flow of working fluid from the diffuser. The screw compressor also includes one or more rotors positioned downstream of the motor portion, where the one or more rotors are configured to at least partially compress the flow of working fluid.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

[0010] FIG. l is a perspective view of an embodiment of a building that may utilize a heating, ventilating, air conditioning, and / or refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure;

[0011] FIG. 2 is a perspective view of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0012] FIG. 3 is a schematic of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0013] FIG. 4 is a cross-sectional view of an embodiment of a screw compressor, in accordance with an aspect of the present disclosure;

[0014] FIG. 5 is a cross-sectional view of an embodiment of a screw compressor, in accordance with an aspect of the present disclosure;

[0015] FIG. 6 is a cross-sectional perspective view of an embodiment of a screw compressor including a vaned diffuser, in accordance with an aspect of the present disclosure;

[0016] FIG. 7 is a cross-sectional side view of an embodiment of an impeller and a vaned diffuser of a screw compressor, in accordance with an aspect of the present disclosure;

[0017] FIG. 8 is a perspective view of an embodiment of an impeller and a vaned diffuser of a screw compressor, in accordance with an aspect of the present disclosure;

[0018] FIG. 9 is an exploded cross-sectional side view of an embodiment of a screw compressor including a vaned diffuser, in accordance with an aspect of the present disclosure;

[0019] FIG. 10 is an exploded perspective view of an embodiment of a screw compressor including a vaned diffuser, in accordance with an aspect of the present disclosure;

[0020] FIG. 11 is a perspective view of an embodiment of a screw compressor including a vaned diffuser, in accordance with an aspect of the present disclosure;

[0021] FIG. 12 is an illustration of a computational fluid dynamics (CFD) simulation for a traditional vaned diffuser; and

[0022] FIG. 13 is an illustration of a CFD simulation for an embodiment of a vaned diffuser with improved features, in accordance with an aspect of the present disclosure.DETAILED DESCRIPTION

[0023] One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0024] When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “anembodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0025] As used herein, the terms “approximately,” “generally,” “substantially,” and so forth, are intended to convey that the property value being described may be within a relatively small range of the property value, as those of ordinary skill would understand. For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to) a given value, this is intended to convey that the property value may be within + / - 5%, within + / - 4%, within + / - 3%, within + / - 2%, within + / - 1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” to another feature, “generally perpendicular” to another feature, and so forth, this is intended to convey that the given feature is within + / - 5%, within + / - 4%, within + / - 3%, within + / - 2%, within + / - 1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular to another feature, and so forth. Mathematical terms, such as “parallel” and “perpendicular,” should not be rigidly interpreted in a strict mathematical sense, but should instead be interpreted as one of ordinary skill in the art would interpret such terms. For example, one of ordinary skill in the art would understand that two lines that are substantially parallel to each other are parallel to a substantial degree, but may have minor deviation from exactly parallel.

[0026] As briefly discussed above, a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system may be used to thermally regulate a space within a building, home, or other suitable structure. For example, the HVAC&R system may include a vapor compression system (e.g., a chiller system) configured to transfer thermal energy between a working fluid (e.g., heat transfer fluid), such as a refrigerant, and a fluid to be conditioned, such as air, water, or brine (e.g., a conditioning fluid). The vapor compression system may include a first heat exchanger (e.g., a condenser) and a second heat exchanger (e.g., an evaporator) that are fluidly coupled to one another via a working fluid circuit. A compressor (e.g., a screw compressor) may be used to circulate the working fluid through the working fluid circuit and, thus, enable the transfer of thermal energy between the working fluid and the fluid to be conditioned via the first heat exchanger, thesecond heat exchanger, or both. In some implementations of the HVAC&R system, the compressor may be a screw compressor.

[0027] Generally, screw compressors include a first rotor (e.g., male rotor, first screw rotor) and a second rotor (e.g., female rotor, second screw rotor) configured to rotate to compress the working fluid. For example, the screw compressor may include a shaft mechanically coupled to the male rotor or the female rotor to drive rotation of the male rotor or the female rotor. The male rotor and the female rotor each include lobes extending radially outward and configured to mesh within corresponding grooves of the other rotor. The screw compressor may direct working fluid (e.g., refrigerant) from an intake portion and into a series of gap created by the lobes and grooves of the male rotor and female rotor, respectively. Upon meshing of the lobes and grooves with working fluid therein, the working fluid may be compress and subsequently discharged from the screw compressor.

[0028] In some embodiments, the screw compressor may include an impeller and diffuser (e.g., mixed flow compressor, mixed flow compressor inlet, mixed flow centrifugal compressor portion), positioned at or in an intake portion of the screw compressor, configured to receive the working fluid directed through the screw compressor. In particular, the impeller and the diffuser may be configured to improve flow of the working fluid into and through the screw compressor. For example, the impeller and / or the diffuser may be implemented to at least partially increase a pressure of the working fluid prior to directing the working fluid to the rotors for further compression. In some instances, the screw compressor may include a motor portion disposed between the intake portion (e.g., impeller and diffuser, mixed flow compressor inlet) and the rotors. Accordingly, the working fluid may be directed from the intake portion (e.g., diffuser) and across components (e.g., stator, rotor, shaft) of the motor portion, thereby cooling the components. However, existing diffusers that may be utilized with screw compressors tend to create flow separation in the working fluid, which disrupts flow of the working fluid through the screw compressor and decreases the efficiency of the screw compressor.

[0029] Accordingly, embodiments of the present disclosure are directed to an improved diffuser configured to be utilized with a screw compressor (e.g., mixed flowcompressor). For example, the diffuser may include diffuser vanes configured to direct, re-direct, and / or adjust flow of the working fluid discharged from the diffuser. The diffuser vanes may include full vanes (e.g., extended vanes, first vanes, full length vanes) that define full vane passages (e.g., first vane passages) configured to receive and direct working fluid from the impeller towards the rotors for further compression. Further, the diffuser may include intermediate vanes (e.g., second vanes, reduced length vanes), which may be positioned within the full vane passages defined by the full vanes. For example, each intermediate vane may be disposed within a respective full vane passage (e.g., between two corresponding, adjacent, or sequential full vanes defining the respective full vane passage). As such, the intermediate vanes and the full vanes may define intermediate vane passages (e.g., second vane passages) within the full vane passages. The intermediate vanes may have a length (e.g., axial length, arc length) that is less than the length of the full vanes. Thus, the intermediate vane passages may receive and divide or split the working fluid flowing through the full vane passages. The intermediate vanes may reduce flow separation and flow losses induced in the working fluid as the working fluid is discharged from the diffuser. In this way, diffusers incorporating the present techniques may reduce energy losses associated with flow separation and may thereby increase screw compressor efficiency.

[0030] Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an application for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system. Such systems, in general, may be applied in a range of settings, both within the HVAC&R field and outside of that field. The HVAC&R systems may provide cooling to data centers, electrical devices, freezers, coolers, or other environments through vaporcompression refrigeration, absorption refrigeration, or thermoelectric cooling. In some applications, HVAC&R systems may be used in residential, commercial, light industrial, industrial, and in any other application for heating or cooling a volume or enclosure, such as a residence, building, structure, and so forth. Moreover, the HVAC&R systems may be used in industrial applications, where appropriate, for cooling and heating of various fluids.

[0031] The illustrated embodiment shows an HVAC&R system for building environmental management that may utilize heat exchangers. A building 10 is cooled bya system that includes a chiller 12 (e.g., chiller system, air-cooled chiller) and a boiler 14. As shown, the chiller 12 is disposed on the roof of building 10, and the boiler 14 is located in the basement; however, the chiller 12 and boiler 14 may be located in other equipment rooms or areas next to the building 10. In accordance with the present techniques, the chiller 12 is an air-cooled chiller that implements a refrigeration cycle to cool water or other conditioning fluid and is configured to reject heat to an ambient (e.g., outdoor) environment surrounding the chiller 12 and / or the building 10. The chiller 12 is housed within a structure that includes a working fluid circuit, a conditioning fluid circuit, and associated equipment such as pumps, valves, and piping. For example, the chiller 12 may be a single package rooftop unit that incorporates a working fluid circuit. In some embodiments, the chiller 12 may also include a free-cooling circuit. The boiler 14 is a closed vessel in which water or other conditioning fluid is heated. The water (e.g., conditioning fluid) from the chiller 12 and the boiler 14 is circulated through the building 10 by conduits 16 (e.g., water conduits). The conduits 16 are routed to air handlers 18 located on individual floors and within sections of the building 10.

[0032] The air handlers 18 are coupled to ductwork 20 that is adapted to distribute air between the air handlers 18 and may receive air from an outside intake. The air handlers 18 include heat exchangers that circulate cold conditioning fluid (e.g., water) from the chiller 12 and hot conditioning fluid (e.g., water) from the boiler 14 to provide heated or cooled air to conditioned spaces within the building 10. Fans within the air handlers 18 draw air through the heat exchangers and direct the conditioned air to environments within building 10, such as rooms, apartments, or offices, to maintain the environments at a designated temperature. A control device 22, shown in the illustrated embodiment as including a thermostat, may be used to designate the temperature of the conditioned air. The control device 22 also may be used to control the flow of air through and from the air handlers 18. Other devices may be included in the system, such as control valves that regulate the flow of conditioning fluid and pressure and / or temperature transducers or switches that sense the temperatures and pressures of the conditioning fluid, the air, and so forth. Moreover, control devices may include computer systems that are integrated withor separate from other building control or monitoring systems, and even systems that are remote from the building 10.

[0033] In some embodiments, the chiller 12 may include a free-cooling system configured to circulate a chilled fluid and place the chilled fluid in a heat exchange relationship with the conditioning fluid circulated through the building to condition (e.g., cool) the conditioning fluid (e.g., water). The free-cooling system configured to circulate the chilled fluid through the chiller 12 may remain outside of the building 10. In other words, the chilled fluid may not enter and / or be circulated through the building 10 (e.g., piping of the building 10). As a result, the chilled fluid may not be subject to certain regulations or codes that may otherwise establish standards, specifications, or requirements to be satisfied to enable implementation of the chiller 12. As such, the chiller 12 may be more readily and / or easily implemented to condition the building 10.

[0034] FIG. 2 is a schematic of an embodiment of a vapor compression system 30 (e.g., mechanical cooling system, air-cooled vapor compression system) having a flash tank 32 (e g., an economizer tank). For example, the vapor compression system 30 may be a part of an air-cooled chiller (e.g., chiller 12). However, it should be appreciated that the disclosed techniques may be incorporated with a variety of other types of chillers. The vapor compression system 30 includes a working fluid circuit 34 (e.g., vapor compression circuit, first working fluid circuit) configured to circulate a working fluid, such as a refrigerant, therethrough with a compressor 36 (e.g., screw compressor) disposed along the working fluid circuit 34. The working fluid circuit 34 also includes the flash tank 32, a condenser 38 (e.g., first condenser, heat exchanger, air-cooled condenser), expansion valves or devices 40, and an evaporator 42 (e.g., liquid chiller, heat exchanger). The components of the working fluid circuit 34 enable heat transfer between the working fluid and other fluids (e.g., a conditioning fluid, air, water) in order to provide cooling to an environment, such as an interior of the building 10.

[0035] Some examples of working fluids that may be used as refrigerants in the vapor compression system 30 are hydrofluorocarbon (HFC) based working fluids, for example, R-410A, R-407, R-134a, hydrofluoro-ol efin (HFO), “natural” refrigerants like ammonia(NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbon based working fluids, water vapor, working fluids with low global warming potential (GWP), or any other suitable working fluid. In some embodiments, the vapor compression system 30 may be configured to efficiently utilize working fluids having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit or less) at one atmosphere of pressure, also referred to as low pressure working fluids, versus a medium pressure working fluids, such as R-134a. As used herein, “normal boiling point” may refer to a boiling point temperature measured at one atmosphere of pressure.

[0036] The vapor compression system 30 may further include a control panel 44 (e.g., a controller) that has an analog to digital (A / D) converter 46, a microprocessor 48, a nonvolatile memory 50, and / or an interface board 52. In some embodiments, the vapor compression system 30 may use one or more of a variable speed drive (VSDs) 54 and a motor 56. The motor 56 may drive the compressor 36 and may be powered by the VSD 54. The VSD 54 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 56. In other embodiments, the motor 56 may be powered directly from an AC or direct current (DC) power source. The motor 56 may include any type of electric motor that can be powered by the VSD 54 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.

[0037] The compressor 36 compresses a working fluid vapor and may deliver the vapor to an oil separator 58 that separates oil from the working fluid vapor. The working fluid vapor is then directed toward the condenser 38, and the oil is returned to the compressor 36. The working fluid vapor delivered to the condenser 38 may transfer heat to a cooling fluid at the condenser 38. For example, the cooling fluid may be ambient air 60 forced across heat exchanger coils of the condenser 38 by condenser fans 62. The working fluid vapor may condense to a working fluid liquid in the condenser 38 as a result of thermal heat transfer with the cooling fluid (e.g., the ambient air 60).

[0038] The liquid working fluid exits the condenser 38 and then flows through a first expansion device 64 (e.g., the expansion device 40, an electronic expansion valve). The first expansion device 64 may be a flash tank feed valve configured to control flow of the liquid working fluid to the flash tank 32. The first expansion device 64 is also configured to lower the pressure of (e.g., expand) the liquid working fluid received from the condenser 38. During the expansion process, a portion of the liquid may vaporize, and thus, the flash tank 32 may be used to separate the vapor from the liquid received from the first expansion device 64. Additionally, the flash tank 32 may provide for further expansion of the liquid working fluid due to a pressure drop experienced by the liquid working fluid when entering the flash tank 32 (e.g., due to a rapid increase in volume experienced when entering the flash tank 32).

[0039] The vapor in the flash tank 32 may exit and flow to the compressor 36. For example, the vapor may be drawn to an intermediate stage or discharge stage of the compressor 36 (e.g., not the suction stage). A valve 66 (e.g., an economizer valve, solenoid valve) may be included in the working fluid circuit 34 to control flow of the working fluid vapor from the flash tank 32 to the compressor 36. In some embodiments, when the valve 66 is open (e.g., fully open), additional liquid working fluid within the flash tank 32 may vaporize and provide additional subcooling of the liquid working fluid within the flash tank 32. The liquid working fluid that collects in the flash tank 32 may be at a lower enthalpy than the liquid working fluid exiting the condenser 38 due to the expansion in the first expansion device 64 and / or the flash tank 32. The liquid working fluid may flow from the flash tank 32, through a second expansion device 68 (e.g., the expansion device 40, an orifice), and to the evaporator 42. In some embodiments, the working fluid circuit 34 may also include a valve 70 (e.g., a drain valve) configured to regulate flow of liquid working fluid from the flash tank 32 to the evaporator 42. For example, the valve 70 may be controlled (e.g., via the control panel 44) based on an amount of suction superheat of the working fluid.

[0040] The liquid working fluid delivered to the evaporator 42 may absorb heat from a conditioning fluid, which may be different from the cooling fluid (e.g., ambient air 60) directed across the condenser 38. The liquid working fluid in the evaporator 42 mayundergo a phase change to become working fluid vapor. For example, the evaporator 42 may include a tube bundle fluidly coupled to a supply line 72 and a return line 74 that are connected to a cooling load. The conditioning fluid (e.g., water, oil, calcium chloride brine, sodium chloride brine) may be directed to enter the evaporator 42 via the return line 74 and to exit the evaporator 42 the via supply line 72. The evaporator 42 may reduce the temperature of the conditioning fluid in the tube bundle via thermal heat transfer with the working fluid so that the conditioning fluid may be utilized to provide cooling for a conditioned environment. The tube bundle in the evaporator 42 may include a plurality of tubes and / or a plurality of tube bundles. In any case, the working fluid vapor exits the evaporator 42 and returns to the compressor 36 by a suction line to complete the working fluid cycle.

[0041] FIG. 3 is a schematic of an embodiment of the vapor compression system 30 that may be used in the HVAC&R system. The illustrated embodiment includes certain elements and element numbers similar to those described above with reference to FIG. 2. In the illustrated embodiment of FIG. 3, the condenser 38 is water cooled and includes a tube bundle 80 connected to a cooling tower 82, which supplies the cooling fluid to the condenser 38. The evaporator 42 may include a tube bundle 84 having a supply line 86S and a return line 86R connected to a cooling load 88. The conditioning fluid of the evaporator 42 (e g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 42 via return line 86R and exits the evaporator 42 via supply line 86S. The evaporator 42 may reduce the temperature of the conditioning fluid in the tube bundle 84 via thermal heat transfer with the working fluid. The tube bundle 84 in the evaporator 42 may include a plurality of tubes and / or a plurality of tube bundles. In any case, the vapor working fluid exits the evaporator 42 and returns to the compressor 36 by a suction line to complete the cycle

[0042] As mentioned above, the compressor 36 may be a screw compressor (e.g., turbo screw compressor, centrifugal-screw compressor). To illustrate, FIGS. 4 and 5 are cross- sectional views of a screw compressor 100 (e.g., compressor 36) that may be used with embodiments of the vapor compression system 30. To facilitate discussion, the screw compressor 100 and its components may be described with reference to a longitudinal axisor direction 102, a lateral axis or direction 104 (e.g., a radial axis or direction), and a vertical axis or direction 106. It should be noted that the vertical axis 106 and the lateral axis 104 extend in generally radial directions relative to the longitudinal axis 102. In the illustrated embodiments, the longitudinal axis 102 extends along (e.g., generally parallel to) an axis 120 (e.g., rotational axis, central axis) of the screw compressor 100. In some embodiments, the screw compressor 100 may include a housing 108 that contains components of the screw compressor 100. As described in greater detail herein, the housing 108 may include and / or define an intake portion 110 (e.g., suction side, an inlet, intake section), a motor portion 112 (e.g., motor section), a compression portion 114 (e.g., compression section), and a discharge portion 116 (e.g., discharge side, an outlet, discharge section).

[0043] Within the housing 108, the motor portion 112 (e.g., motor) may include a rotor 138, a stator 140, and a shaft 142. The shaft 142 may extend along the axis 120 through the intake portion 110, the motor portion 112, and the compression portion 114. The rotor 138 and stator 140 may extend along the axis 120 and may generally encircle the shaft 142. In some embodiments, the shaft 142 may be connected (e.g., mechanically connected, welded, coupled) to both an impeller 136 (e g., centrifugal impeller, centrifugal intake) positioned within the intake portion 110 and a male rotor 118 disposed within the compression portion 114. In operation, the rotor 138 and the stator 140 (e.g., the motor) may convert electrical energy to mechanical energy and may drive rotation of the shaft 142 about the axis 120. In this way, the shaft 142 may rotate both the impeller 136 and the male rotor 118.

[0044] The screw compressor 100 also includes a female rotor 124 disposed within the compression portion 114. In operation, the male rotor 118 may rotate about the axis 120, and the female rotor 124 may rotate about an axis 126. In some embodiments, the axes 120 and 126 may extend substantially parallel with one another. For example, the male rotor 118 may generally extend from within the compression portion 114 to the discharge portion 116 in a direction substantially parallel to the longitudinal axis 102, and the femalerotor 124 may extend within the compression portion 114 to the discharge portion 116 in a direction substantially parallel to the longitudinal axis 102.

[0045] The male rotor 118 may include one or more protruding lobes 122 disposed circumferentially about the male rotor 118. The female rotor 124 may include one or more corresponding grooves 128 disposed circumferentially about the female rotor 124 that are configured to receive and / or engage with the lobes 122 of the male rotor 118. The lobes 122 of the male rotor 118 may mesh with the corresponding grooves 128 on the female rotor 124 to form a series of gaps 130 between the male and female rotors 118, 124. It should be noted that the male rotor 118 may also include grooves, and the female rotor 124 may include corresponding lobes configured to form a portion or subset of the gaps 130. The gaps 130 may continually and / or continuously compress working fluid directed through the screw compressor 100 as the working fluid flows through the compression portion 114. The compressed working fluid may then be directed toward a discharge port 132, illustrated in FIG. 5, of the discharge portion 116. For example, during operation of the screw compressor 100, the gaps 130 may continuously reduce in volume as the male and female rotors 118, 124 rotate and thereby compress the working fluid along the length of the male and female rotors 118, 124 within the compression portion 114.

[0046] The rotor 118, 124 (e.g., male rotor 118 and female rotor 124) design parameters (e.g., size, quantity of lobes / grooves, and / or shape) may be any design parameter suitable to compress working fluid to a desired pressure. Indeed, the rotor 118, 124 design parameters may depend on, or are at least partially based on, one or more operating parameters of the screw compressor 100, one or more operating conditions of the screw compressor 100, a type of the working fluid, a type of the vapor compression system 30 and / or HVAC&R system having the screw compressor 100, another suitable operating parameter, or any combination thereof.

[0047] In the illustrated embodiment, the working fluid directed through the intake portion 110 may then be directed over one or more of the components within the motor portion 112 (e.g., stator 140, rotor 138, shaft 142) of the screw compressor 100. In this way, the working fluid may cool (e.g., absorb thermal energy) the components of the motorportion 112 to the working fluid, thereby reducing inefficiencies and mechanical wear due to heat. From the motor portion 1 12, the working fluid may be directed through the compression portion 114 to be compressed via the gaps 130 of the male and female rotors 118, 124. The compressed working fluid may be discharged from the screw compressor 100 via the discharge port 132 of the discharge portion 116 and directed towards other components of the HVAC&R system (e.g., condenser 38).

[0048] Returning to the intake portion 110, as discussed above, the screw compressor 100 may include the impeller 136 positioned within the intake portion 114 of the screw compressor 100 (e.g., at least partially within the housing 108 of the screw compressor 114). To illustrate, FIG. 6 is a cross-sectional perspective view of an embodiment of the screw compressor 100, showing a diffuser 137 (e.g., mixed flow diffuser) coupled between the impeller cap 144 and the housing 108. The impeller cap 144 may include and / or define an inlet 146 (e.g., inlet port, inlet hole, inlet aperture) configured to receive a flow of working fluid and direct the flow of working fluid to an impeller inlet 148 of the impeller136. As will be appreciated, the inlet 146 of the impeller cap 144 and the impeller inlet 148 may include a dimension (e.g., diameter, radius, circumference) based on and / or associated with a type of working fluid, one or more operating conditions of the screw compressor 100, and / or any other relevant parameters. The impeller cap 144 may be attached or fixed to the diffuser 137 in any suitable manner, such as mechanical fasteners extending axially, along the axis 120, through the impeller cap 144 and into the diffuser137. In some embodiments, the impeller cap 144 may be coupled to (e.g., coupled directly to) the housing 108, and the diffuser 137 may be positioned within the impeller cap 144 and / or the housing 108. The impeller 136 and the diffuser 137 may be collectively referred to as a mixed flow intake (e.g., mixed flow centrifugal compressor) of the screw compressor 100. It should be appreciated that the impeller 136 and the diffuser 137 may also be implemented with other types of compressors, in accordance with the present techniques.

[0049] The impeller 136 may receive working fluid (e.g., gaseous working fluid, vapor working fluid) via the impeller inlet 148. As discussed in detail below, the working fluid may be directed into the impeller inlet 148 of the impeller 136 in a direction along thelongitudinal axis 102 (e.g., axial direction relative to axis 120). The impeller 136 may be driven into rotation (e.g., via the motor) about the axis 120, and one or more impeller blades 149 may impart mechanical energy to the working fluid, which may cause the working fluid to accelerate at least partially in a radial outward and / or lateral direction (e.g., radial direction relative to axis 120) due to the force (e.g., rotational force, centrifugal force) imparted by the impeller 136 and at least partially in the direction along the longitudinal axis 102 (e.g., axial direction relative to the axis 120). Indeed, as the impeller 136 is rotated, a swirling or rotational flow pattern (e.g., circumferential flow component) of the working fluid within the intake portion 110 may be generated. For example, the working fluid may have a relatively high rotational velocity (e.g., in a circumferential direction about the axis 120) as the working fluid is discharged from the impeller 136.

[0050] The working fluid discharged from the impeller 136 may be directed into and through the diffuser 137 positioned at least partially within the housing 108 and downstream of the impeller 136, relative to a flow direction of working fluid through the screw compressor 100. The diffuser 137 may be configured to reduce a velocity of the working fluid discharged from the impeller 136 and / or to redirect the working fluid from a radial direction and / or a circumferential direction into a more fully or substantially axial direction, relative to axis 120. That is, the diffuser 137 may be configured to reduce a radial outward flow component and / or circumferential flow components of the flow of working fluid and to promote (e.g., redirect) flow of the working fluid in an axial direction (e.g., along axis 120). In some embodiments, the diffuser 137 may be configured to redirect the flow of working fluid from a radial outward direction as the flow of working fluid exits the impeller 136, to a radial inward direction, relative to the axis 120. In this way, the flow of working fluid may be directed through the motor portion 112 (e.g., downstream of the intake portion 110) more substantially in the axial direction, relative to the axis 120.

[0051] The diffuser 137 may include an inner wall 164 (e.g., inner radial wall, inner circumferential wall, inner annular wall, inner diffuser wall, hub) and an outer wall 166 (e.g., outer radial wall, outer circumferential wall, outer annular wall, outer diffuser wall, shroud) that cooperatively define a diffuser flow path 170 extending through the diffuser 137. In some embodiments, the inner wall 164 may generally extend in a direction alongthe axis 120 and may include a first radial position relative to the axis 120, the outer wall 166 may generally extend in the direction along the axis 120 and may include a second radial position relative to the axis 120, and the first radial position may be different from the second radial position. For example, the first radial position may be radially within the second radial position. The inner wall 164 and the outer wall 166 may define a diffuser inlet 171, downstream of the impeller 136, relative to the flow of working fluid, and configured to receive the flow of working fluid from the impeller 136. The inner wall 164 and the outer wall 166 may also define a diffuser outlet 173, downstream of the diffuser inlet 171, relative to the flow of working fluid, and configured to discharge the flow of working fluid from the diffuser 137. In an embodiment, the diffuser outlet 173 may expand or widen (e.g., radially expand) relative to an upstream portion of the diffuser flow path 170, thereby enabling the flow of working fluid to be distributed (e.g., spread) upon discharge from the diffuser 137. For example, at the diffuser outlet 173, the inner wall 164 may curve radially inward and the outer wall 166 may curve radially outward relative to the axis 120, expanding away from one another along a length of the diffuser outlet 173.

[0052] In some embodiments, the diffuser 137 may include an inner flange 172 (e.g., inner support, inner collar) extending radially inward from the inner wall 164. In some embodiments, the inner flange 172 may be configured to support or engage with one or more components of the screw compressor 100. For example, the inner flange 172 may be configured to support one or more bearings of the screw compressor 100, which may provide support (e.g., axial support, radial support) for the shaft 142. In some embodiments, the diffuser 137 may also include an outer flange 175 configured engage with the housing 108 and / or the impeller 136. For example, the outer flange 175 may attach (e.g., mechanically couple) the diffuser 137 to the housing 108 and / or the impeller 136, such as via one or more suitable attachment devices (e.g., fasteners, bolts, welding, chemical adhesives, interference fit, friction fit).

[0053] As described in further detail below, the diffuser 137 also includes an arrangement of vanes disposed within the diffuser flow path 170. For example, one or more of the vanes may extend (e.g., radially and / or circumferentially) from the inner wall 164, one or more of the vanes may extend (e.g., radially and / or circumferentially) from theouter wall 166, and / or one or more of the vanes may extend from the inner wall 164 to the outer wall 166. The vanes include geometries, arrangements, configurations, and / or other characteristics configured to enable improved flow of the working fluid through the diffuser 137 and through the screw compressor 100. In particular, the vanes are configured to enable improved flow of the working fluid by reducing flow losses, reducing flow separation induced in the working fluid, and / or increasing a pressure rise of the working fluid directed through the diffuser 137. In this way, embodiments of the diffuser 137 described herein are configured to enable increased efficiency of the screw compressor 100.

[0054] Although the present disclosure describes embodiments of the diffuser 137 as incorporated with the screw compressor 100, it should be appreciated that embodiments of the diffuser 137 including one or more of the features disclosed herein may have other configurations and / or may be utilized with any other suitable type of compressor. For example, the diffuser 137 may be configured as a mixed flow diffuser (e.g., mixed flow to axial diffuser) and may be incorporated with a centrifugal compressor or other type of compressor (e.g., dynamic compressor). In some embodiments, the diffuser 137 may be incorporated with a combination of two or more compressors, which may be the same type of compressor or different types of compressors. That is, one or more compressors of a system having multiple compressors may include an embodiment of the diffuser 137. In some embodiments, the diffuser 137 may be stand alone, and may not include other compressions components (e.g., the compression portion 114, discharge portion 116).

[0055] FIG. 7 is a cross-sectional side view of a portion of an embodiment of the screw compressor 100, illustrating the intake portion 110 having the impeller 136 and the diffuser 137, in accordance with aspects of the present disclosure. As shown, the impeller 136 may include an outer wall 160 (e.g., outer radial wall, outer circumferential wall, outer annular wall, outer impeller wall) and an inner wall 162 (e.g., inner radial wall, inner circumferential wall, inner annular wall, inner impeller wall) that individually and / or cooperatively define a flow path of the impeller 136 having a first section 150 and a second section 152 of the impeller 136. The first section 150 (e.g., first impeller section, intake section) may include the impeller inlet 148 that is configured to receive the working fluid(e.g., gaseous working fluid, gaseous refrigerant, vapor working fluid) in a substantially axial direction, such as along the axis 120. The second section 152 may extend in a radially outward direction from the first section 150, relative and along the axis 120, and may redirect the working fluid at least partially in the radially outward direction.

[0056] The first section 150 may include a first radial cavity 154 defined by the inner wall 162 and the outer wall 160. The first radial cavity 154 may extend axially from the impeller inlet 148 along the axis 120 and into the screw compressor 100. The second section 152 may include a second radial cavity 156 extending semi-radially and / or semi- axially (e.g., radially and axially, extending at least partially along the axis 120 and at least partially away from the axis 120, diagonal direction) from the first radial cavity 154. In this way, working fluid may enter the screw compressor 100 and the impeller 136 in generally an axial direction, along to axis 120, and the impeller 136 may redirect the working fluid to flow in a semi-radial and / or semi-axial direction (e.g., angled direction, axial and radial direction), relative to the axis 120.

[0057] As briefly mentioned above, the impeller 136 may include one or more impeller blades 149 extending through the first radial cavity 154 and the second radial cavity 156. The impeller blades 149 may extend from the inner wall 162, the outer wall 160, or both and may be positioned crosswise relative to the inner wall 162 and / or the outer wall 160. In some embodiments, the impeller blades 149 may be arrayed about the axis 120 and may be spaced equidistantly relative to one another within the impeller 136. As should be appreciated, the spacing, size, geometry, arrangement, curvature, and / or any other characteristic of the impeller blades 149 is not limited to that shown in the illustrated embodiment and may be any characteristic desired and / or suitable.

[0058] In any case, the impeller blades 149, the outer wall 160, and the inner wall 162 may define one or more impeller passages 163 extending through the impeller 136. Each impeller passage 163 may include an inlet opening 165 configured to receive working fluid from the impeller inlet 148. Further, proximate an outlet of the impeller 136, each impeller passage 163 may include an outlet opening 168 configured to discharge the working fluid from the impeller 136 and direct the working fluid toward the diffuser 137. In anembodiment, the outlet opening 168 of a respective impeller passage 163 may abut the diffuser inlet 171, such that working fluid is directed from the impeller passage 163 and directly into the diffuser passage 170. As will be appreciated, a size, dimension, geometry, configuration, cross-sectional area, and / or other characteristic of the inlet openings 165 may be different than that of the outlet openings 168 to enable desired adjustments to the flow of working fluid (e.g., change in velocity) directed through the impeller 136. Additionally or alternatively, a size, dimension, geometry, configuration, shape, arrangement, and / or other characteristic of the impeller blades 149 may be based on a desired change in the flow of working fluid directed through the impeller 136.

[0059] Further, as discussed above, the impeller 136 may be attached (e.g., mechanically coupled) to the shaft 142, which is configured to transfer a rotational force from the motor to the impeller 136. For example, the shaft 142 may be actuated to rotate in a counter-clockwise direction, thereby rotating the impeller 136 in a counter-clockwise direction. In other embodiments, the impeller 136 and shaft 142 may be configured to rotate in a clockwise direction during operation. As should be appreciated, the rotational direction of the shaft 142 and the impeller 136 may be at least partially based on the configuration (e.g., curvature) of impeller blades 149, a configuration of the motor components (e.g., stator, rotor), and / or a configuration of compression rotors within the screw compressor 100 (e.g., male rotor, female rotor).

[0060] As the impeller 136 is driven into rotation, the impeller blades 149 may drive the working fluid to flow at least partially radially outward (e.g., relative to the axis 120) through each impeller passage 163, thereby increasing a velocity of the flow of working fluid. As discussed above, upon exiting the impeller 136 via the outlet openings 168, the working fluid may further flow through the diffuser 137 via the diffuser inlet 171. In the illustrated embodiment, the diffuser 137 includes the inner wall 164 and the outer wall 166 defining the diffuser flow path 170 configured to receive the working fluid from the impeller 136, as described above. The diffuser flow path 170 may extend at least partially in an axial direction along the axis 120 and partially in a radially inward direction. As such, working fluid exiting the impeller 136 in a radially outward direction (e.g., partially radial and partially axial direction), relative to axis 120, may be received by the diffuserinlet 171 and redirected into a more substantially axial direction along the axis 120. Upon flowing through the diffuser 137, the working fluid is discharged via the diffuser outlet 173 across one or more motor components (e.g., stator 140, rotor 138) within the motor portion 112 of the screw compressor 100. In this way, the working fluid may function as a coolant to reduce a temperature of the motor components, which may improve operation of the motor (e.g., reduce operational interruptions) and further increase the efficiency of the screw compressor 100.

[0061] As will be appreciated, rotation of the impeller 136, the configuration of the impeller blades 149, and the flow direction of the working fluid discharged by the impeller 136 (e.g., due to the at least partially radial orientation of the second radial cavity 156), the working fluid discharged by the impeller 136 may have a flow pattern and / or flow component extending at least partially in a circumferential direction about the axis 120. As such, the diffuser 137 may include one or more diffuser vanes 174 configured to redirect flow of the working fluid through the screw compressor 100. That is, the diffuser vanes 174 are configured to adjust (e.g., reduce) a flow pattern and / or a flow component (e.g., a circumferential flow component) of the working fluid to enable flow of the working fluid in the direction along the axis 120. Additionally or alternatively, the diffuser 137 generally may be configured to redirect the working fluid to flow at least partially radially inward relative to the axis 120. It is noted that FIG. 7 illustrates a simplified representation of the diffuser vanes 174 of the diffuser 137 for clarity and ease of understanding. For example, the diffuser vanes 174 are illustrated with their respective profiles (e.g., shroud intersect interfaces) and without additional features (e.g., hub intersect interfaces).

[0062] In some embodiments, the diffuser vanes 174 are configured to recover energy (e.g., kinetic energy) of the working fluid in the circumferential direction (e.g., a swirl direction) and increase a pressure (e.g., static pressure) of the working fluid. For example, the diffuser vanes 174, the inner wall 164, and the outer wall 166 may define one or more diffuser passages 176 that may capture or otherwise redirect a flow component of the working fluid flowing in a diagonal or circumferential (e.g., swirling) direction to an axial direction, relative to the axis 120. In this way, the diffuser vanes 174 may recover and convert energy associated with high velocity flow of the working fluid in thecircumferential direction to pressure energy. Thus, the diffuser vanes 174 enable a reduction of flow losses of the working fluid and enable an increased pressure of the working fluid discharged from the diffuser 137.

[0063] FIG. 8 is a perspective view of a portion of an embodiment of the screw compressor, illustrating the impeller 136 and the diffuser 137, in accordance with aspects of the present disclosure. As discussed above, the diffuser 137 may be positioned downstream of the impeller 136 relative to a flow direction of the working fluid through the intake portion 110. The working fluid discharged from the impeller 136 may have an increased circumferential flow component (e.g., rotational flow, swirl), relative to the axis 120. The diffuser 137 may be configured to redirect the flow of working fluid such that the circumferential flow component of the working fluid is reduced and the working fluid is directed to flow more substantially along the axis 120 (e.g., in an axial direction). For example, the diffuser vanes 174 may define the diffuser passages 176 configured to capture and redirect the working fluid to convert the energy associated with the rotational velocity (e.g., circumferential flow, swirling flow) of the working fluid to pressure energy, thereby enabling an increase in the pressure of the working fluid.

[0064] In accordance with present techniques, at least a subset of the diffuser vanes 174 may have a geometry, configuration, dimension, or other characteristic that differs from that of another subset of the diffuser vanes 174. For example, the diffuser vanes 174 may include one or more full vanes 178 (e.g., a first subset of diffuser vanes 174, extended vanes, first vanes) and one or more intermediate vanes 180 (e.g., splitter vanes, a second subset of diffuser vanes 174, second vanes). Each full vane 178 may include a trailing edge portion 182 (e.g., first trailing edge portion) adjacent to (e.g., proximate) the diffuser outlet 173 of the diffuser flow path 170. The trailing edge portion 182 may include a trailing edge 183 (e.g., trailing edge surface) extending cross wise to the inner wall 164 and / or the outer wall 166. Each full vane 178 may also include a leading edge portion 184 (e.g., first leading edge portion) adjacent to (e.g., proximate) the diffuser inlet 171 of the diffuser flow path 170. The leading edge portion 184 may include a leading edge 185 (e.g., leading edge surface) extending cross wise to the inner wall 164 and / or the outer wall 166. In an embodiment, the leading edge portion 184 may extend from the trailing edge portion182 towards the diffuser inlet 171 in a curved orientation. For example, the leading edge portion 184 may be angled different than the trailing edge portion 182, such as relative to the axis 120 and illustrated in greater detail in FIG. 9. In particular, the leading edges portion 184 may extend at least partially in a direction into the flow of working fluid received by the diffuser 137 (e.g., in a first circumferential direction opposite a second circumferential direction of the flow of working fluid). Further, the trailing edge portion 182 of the full vanes 178 may be arranged to extend in a relatively more axial direction relative to the axis 120, such as compared to an angle or orientation of the leading edge portion 184 relative to the axis 120. As such, the full vanes 178 may have a curved or arcuate shape or orientation configured to redirect circumferential flow of working fluid to a more axial flow along the axis 120. In this way, working fluid discharged the impeller 136 may be at least partially redirected from a circumferential direction relative to the axis 120 to a more substantially axial direction relative to the axis 120.

[0065] The full vanes 178 may be arrayed about a circumference of the diffuser flow path 170 (e.g., about the axis 120). In some embodiments, the full vanes 178 may be equidistantly spaced from one another about the circumference of the diffuser flow path 170. In other embodiments, the full vanes 178 may be unevenly spaced from one another within the diffuser flow path 170. The full vanes 178 may define full vane passages 186 (e.g., extended passages, primary passages, initial passages, upstream passages, first passages) of the diffuser passages 176. In operation, the full vane passages 186 may initially receive the working fluid from the impeller 136. As will be appreciated, respective widths of the full vane passages 186 may enable an increased flow rate of the working fluid through the impeller 136 and the diffuser 137, while also enabling a desired increase in pressure of the working fluid. In this way, the screw compressor 100 may operate at an increased capacity.

[0066] In some embodiments, one or more of the full vanes 178 may include a two- dimensional (2-D) shape, geometry, or configuration. Indeed, as described above, each full vane 178 may extend at least partially in a circumferential direction about the axis 120 and at least partially along the axis 120. Additionally, the intermediate vanes 180 may each include a shroud intersect interface 191 (e.g., intersecting with the outer wall 166) anda hub intersect interface 193 (e.g., intersecting with the inner wall 164). In some embodiments, the full vane 178 may extend from the outer wall 166 at the shroud intersect interface 191 at an angle (e.g., lean angle) that is substantially similar to an angle at which the full vane 178 extends from the inner wall 164 at the hub intersect interface 193.

[0067] In other embodiments, one or more of the full vanes 178 may include a three- dimensional (3-D) shape, geometry, or configuration. For example, the full vane 178 may extend from the outer wall 166 at the shroud intersect interface 191 at a first angle (e.g., lean angle), and the full vane 178 may extend from the inner wall 164 at the hub intersect interface 193 at a second angle, different from the first angle. In this way, the full vanes 178 may include a curved or twisting shape (e.g., 3-D shape) along a width (e.g., radial dimension relative to the axis 120) of the full vane 178. The 3-D shape may enable decreased flow separation of the working fluid directed through the diffuser 137, thereby decreasing energy loss associated with flow separation, and further increasing the efficiency of the screw compressor 100. The respective angles (e.g., lean angles) of the full vane 178 at the shroud intersect interface 191 and the hub intersect interface 193 may be any angle suitable to reduce flow separation of the working fluid discharged by the diffuser 137. Further, the respective angles of the full vane 178 at the shroud intersect interface 191 and the hub intersect interface 193 may vary along a length 187 (e.g., arc length) of the full vanes 178. In this way, the full vanes 178 may include a twisting shape (e.g., 3-D shape) along the length 187 of the full vanes 178. The twisting or 3-D shape may enable decreased flow separation of the working fluid directed through the diffuser 137, thereby decreasing energy loss associated with flow separation, and further increasing the efficiency of the screw compressor 100.

[0068] The intermediate vanes 180 may also be arrayed within the diffuser flow path 170 and about the axis 120. For example, each intermediate vane 180 may be positioned between (e.g., circumferentially between) two adjacent full vanes 178 and / or within the full vane passage 186 defined by the adjacent full vanes 178. In some embodiments, the full vanes 178 and the intermediate vanes 180 may be arrayed about the circumference of the diffuser flow path 170 in an alternating arrangement. In general, respective lengths 189 (e.g., dimension, arc length) of the intermediate vanes 180 may be less than the respectivelengths 187 of the full vanes 178. For example, the length 189 of the intermediate vanes 180 may be approximately 15 percent, 20 percent, 30 percent, 40 percent, 50 percent, 60 percent, 70 percent, or 80 percent of the length 187 of the full vanes 178. Indeed, the length 189 of the intermediate vanes 180 between 20% and 70% of the length 187 of the full vanes may further reduce flow separation and flow loss of the working fluid discharged from the diffuser 137. In some embodiments, one or more intermediate vanes 180 may have different lengths (e.g., increased length, decreased length) relative to one another. In some embodiments, one or more of the intermediate vanes 180 may be positioned within one of the full vane passages 186 and approximately equidistantly from the two adjacent (e.g., sequential) full vanes 178 (e.g., in a circumferential direction) defining the full vane passage 186. As used herein, adjacent full vanes refer to two full vanes 178 that are most proximate irrespective of any intermediate vane 180 and / or supplemental vane positioned therebetween.

[0069] The intermediate vanes 180 positioned within the full vane passages 186 defined by corresponding adjacent full vanes 178 may further define one or more intermediate vane passages 188 (e.g., reduced passages, second passages, discharge passages, downstream passages) within each full vane passage 186. As such, working fluid flow entering each full vane passage 186 may be split or otherwise divided by the intermediate vane 180 and may be directed to flow along two intermediate vane passages 188. In particular, the working fluid may initially flow into an opening (e g., wide opening) of the full vane passage 186 and then flow along the full vane passage 186 toward the intermediate vane 180 positioned within the full vane passage 186. The intermediate vane 180 may then divide the flow of working fluid within the full vane passage 186 and may direct divided flows of the working fluid to flow through the intermediate vane passages 188. As such, the addition of the intermediate vanes 180 defining the intermediate vane passages 188 may not reduce an amount of working fluid directed through the diffuser passages 176. Further, the positioning of the intermediate vanes 180 within each of the full vane passages 186 (e.g., downstream of the leading edge portion 184) may enable an increased flow rate of working fluid through the full vane passages 186 while also decreasing flow separation within the working fluid discharged by the diffuser 137. In thisway, the working fluid may flow through the diffuser 137 and the screw compressor 100 more efficiently.

[0070] In some embodiments, one or more of the intermediate vanes 180 may include a two-dimensional (2-D) shape, geometry, or configuration. Indeed, as described above, each intermediate vane 180 may extend at least partially in a circumferential direction about the axis 120 and at least partially along the axis 120. Additionally, the intermediate vanes 180 may each include a shroud intersect interface 194 (e.g., intersecting with the outer wall 166) and a hub intersect interface 196 (e.g., intersecting with the inner wall 164). In some embodiments, the intermediate vane 180 may extend from the outer wall 166 at the shroud intersect interface 194 at an angle (e.g., lean angle) that is substantially similar to an angle at which the intermediate vane 180 extends from the inner wall 164 at the hub intersect interface 196.

[0071] In other embodiments, one or more of the intermediate vanes 180 may include a three-dimensional (3-D) shape, geometry, or configuration. For example, the intermediate vane 180 may extend from the outer wall 166 at the shroud intersect interface 194 at a first angle (e.g., lean angle), and the intermediate vane 180 may extend from the inner wall 164 at the hub intersect interface 196 at a second angle different from the first angle. In this way, the intermediate vanes 180 may include a curved or twisting shape (e.g., 3-D shape) along a width (e.g., radial dimension relative to the axis 120) of the intermediate vane 180. The 3-D shape may enable decreased flow separation of the working fluid directed through the diffuser 137, thereby decreasing energy loss associated with flow separation, and further increasing the efficiency of the screw compressor 100. The respective angles (e g., lean angles) of the intermediate vane 180 at the shroud intersect interface 194 and the hub intersect interface 196 may be any angle suitable to reduce flow separation of the working fluid discharged by the diffuser 137. Further, the respective angles of the intermediate vane 180 at the shroud intersect interface 194 and the hub intersect interface 196 may vary along the length 189 (e.g., arc length) of the intermediate vanes 180. In this way, the intermediate vanes 180 may include a twisting shape (e.g., 3- D shape) along the length 189 of the intermediate vanes 180. The twisting or 3-D shape may enable decreased flow separation of the working fluid directed through the diffuser137, thereby decreasing energy loss associated with flow separation, and further increasing the efficiency of the screw compressor 100.

[0072] In some embodiments, each intermediate vane 180 may include a trailing edge portion 190 (e.g., second trailing edge portion) adjacent to (e.g., proximate) the diffuser outlet 173. The trailing edge portion 190 may include a trailing edge 195 (e.g., trailing edge surface) extending cross wise to the inner wall 164 and / or the outer wall 166. Each intermediate vane 180 may also include a leading edge portion 192 (e.g., second leading edge portion) extending from the trailing edge portion 190 in an upstream direction, relative to the flow of working fluid. The leading edge portion 192 may include a leading edge 197 (e.g., leading edge surface) extending cross wise to the inner wall 164 and / or the outer wall 166. In some embodiments, the trailing edge portions 190 of the intermediate vanes 180 may be generally aligned with the trailing edge portions 182 of the full vanes 178. In other words, the trailing edge portions 190 of the intermediate vanes 180 and the trailing edge portions 182 of the full vanes 178 may be generally arranged at a common axial location along the axis 120. As discussed above, the intermediate vanes 180 may include the length 189 (e.g., arc length) that is less than that of the full vanes 178, thus the leading edge portion 192 of the intermediate vanes 180 may be disposed within the full vane passages 186. Further, the leading edge portions 192 of the intermediate vanes 180 may be offset (e.g., axially offset, relative to the axis 120) from the leading edge portions 184 of the full vanes 178. Specifically, the leading edge portions 184 of the full vanes 178 may be disposed upstream of the leading edges portions 192 of the intermediate vanes 180 relative to a flow direction of the working fluid along the diffuser flow path 170. In some embodiments, the leading edge 197 may include a narrowing point or edge that has a reduced dimension (e.g., width) relative to that of a main body portion of the intermediate vane 180. In this way, working fluid flowing through the full vane passages 186 may experience a reduced amount of resistance as the flow of working fluid is split or divided by the leading edge 197 of the intermediate vane 180. Further, the narrowed or taperedgeometry of the leading edge 197 may enable reduced flow separation of the working fluid, which may enable increased efficiency of the screw compressor 100.

[0073] In some embodiments, the leading edge portion 192 of the intermediate vanes 180 may be angled, such as relative to the axis 120, similar to the leading edge portion 184 of the full vanes 178 illustrated further in FIG. 9. In particular, the leading edge portion 192 may extend at least partially in a direction into the flow of working fluid received by the diffuser 137 (e.g., in a first circumferential direction opposite a second circumferential direction of the flow of working fluid). Further, the trailing edge portions 190 of the intermediate vanes 180 may be arranged to extend in a more axial direction along the axis 120, such as compared to an angle or orientation of the leading edge portion 192. As such, the intermediate vanes 180 may have a curved or arcuate shape configured to redirect circumferential flow of working fluid to a more axial flow along the axis 120. In this way, working fluid discharged the impeller 136 may be at least partially redirected from a circumferential direction relative to the axis 120 to a more substantially axial direction relative to the axis 120.

[0074] The intermediate vanes 180 may include a thickness 198 having any suitable dimension or magnitude to enable efficient flow of working fluid through the diffuser 137. In some embodiments, the thickness 198 may be at least partially based on or associated with a type of working fluid directed through the screw compressor 100. In other embodiments, a magnitude of the thickness 198 may be at least partially based on or associated with desired operating conditions and / or parameters of the screw compressor 100. In further embodiments, a magnitude of the thickness 198 of the intermediate vanes 180 may be different (e g., less than, greater than) than a magnitude of a thickness of the full vanes 178. In any case, the thickness 198 of the intermediate vanes 180 may reduce the flow separation of working fluid discharged by the diffuser 137, thereby increasing the efficiency of the screw compressor 100. In an embodiment, the thickness of theintermediate vane 180 may vary (e.g., increase, decrease) along the length 189 and / or the width (e.g., radial dimension relative to the axis 120) of the intermediate vane 180.

[0075] In further embodiments, the diffuser 137 may include one or more supplemental vanes (e.g., additional vanes, third vanes) different in characteristic from the full vanes 178 and the intermediate vanes 180. In an embodiment, the supplemental vanes may be positioned within and / or in between one of the full vanes 178 and one of the intermediate vanes 180 (e.g., within one of the intermediate vane passages 188) within a space 200. Additionally or alternatively, the supplemental vanes may be positioned within and / or in between two sequential or adjacent full vanes 178 and / or between two sequential or adjacent intermediate vanes 180. Any number of supplemental vanes may be positioned circumferentially about the diffuser flow path 170. The one or more supplemental vanes may include a length that may be less than, such as a fraction (e.g., 15 percent 20 percent, 30 percent, 40 percent, 50 percent, 60 percent, 70 percent, 80 percent) of the length 189 of the intermediate vane 180 and / or may be less than, such as a fraction (e.g., 5 percent, 10 percent, 15 percent, 20 percent, 25 percent, 30 percent) of the length 187 of the full vane 178. The supplemental vane may define one or more supplemental vane passages extending between the supplemental vane and one of the full vanes 178 and / or between the supplemental vane and one of the intermediate vanes 180. The supplemental vane may split or divide a flow of the working fluid directed through the intermediate vane passage 188 to flow through the supplemental vane passages 202. As such, the working fluid directed through the diffuser 137 may experience a reduced amount of flow separation, thereby decreasing associated flow losses and increasing the overall efficiency of the screw compressor 100.

[0076] FIGS. 9, 10, and 11 illustrate additional views of embodiments of the screw compressor 100 in accordance with the present techniques. In particular, the illustrated embodiments include the intake portion 110 of the screw compressor 100 having the diffuser 137 with an arrangement of vanes configured to enable reduced flow separation, reduced losses, and improved efficiency in a flow of working fluid directed through the screw compressor 100. Discussed above, the flow of working fluid may be discharged from the diffuser 137 (e.g., the diffuser outlet 173) and may be directed across the one ormore components of the motor within the motor section 112, providing cooling. It is noted that FIG. 9 illustrates a simplified representation of the full diffuser vanes 178 and the intermediate diffuser vanes 180 for clarity and ease of understanding. For example, the full diffuser vanes 178 and the intermediate diffuser vanes 180 are illustrated with their respective profiles (e.g., shroud intersect interfaces 191, 194) and without additional features (e.g., hub intersect interfaces 193, 196).

[0077] As discussed above, the leading edge portion 184 of the full vanes 178 may extend and / or may face at least partially in a circumferential direction relative to the axis 120 at a first angle 208, the trailing edge portion 182 may extend at a second angle 210 relative to the axis 120, and the first angle 208 may be different (e.g., larger, smaller) than the second angle 210. In the illustrated embodiment of FIG. 9, the first angle 208 may be greater (e.g., more circumferential) than the second angle 210 (e.g., more axial), relative to the axis 120. Similarly, the leading edge portion 192 of the intermediate vanes 180 may extend and / or may face at least partially in a circumferential direction relative to the axis 120 at a first angle 212, the trailing edge portion 190 may extend at a second angle 214 relative to the axis 120, and the first angle 212 may be different (e.g., larger, smaller) than the second angle 214. In the illustrated embodiment of FIG. 9, the first angle 212 may be greater (e.g., more circumferential) than the second angle 214 (e.g., more axial), relative to the axis 120. In this way, working fluid discharged the impeller 136 may be at least partially redirected from a circumferential direction relative to the axis 120 to a more substantially axial direction relative to the axis 120.

[0078] FIGS. 12 and 13 are illustrations of computational fluid dynamics (CFD) simulations for different diffusers. In particular, FIG. 12 illustrates a first CFD simulation 204 for a traditional vaned diffuser that does not include features described herein. As shown, the CFD simulation for the traditional vaned diffuser shows large flow separation and high flow losses. FIG. 13 illustrates a second CFD simulation 206 for an embodiment of the diffuser 137 that includes features incorporating the present techniques (e.g., full vanes 178 and intermediate vanes 180). As illustrated, the diffuser 137 having the fullvanes 178 and the intermediate vanes 180 in FIG. 13 enables reductions in flow separation and flow losses.

[0079] While only certain features and embodiments of the disclosure have been illustrated and described, many modifications and changes may occur to those skilled in the art, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, including temperatures and pressures, mounting arrangements, use of materials, colors, orientations, and so forth without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or resequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.

[0080] Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode of carrying out the disclosure, or those unrelated to enabling the claimed disclosure. It should be noted that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.

[0081] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function], ..” or “step for [perform]ing [a function]...”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Claims

CLAIMS:

1. A screw compressor for a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system, wherein the screw compressor comprises: an impeller configured to rotate about an axis and configured to receive a working fluid directed into the impeller along the axis, wherein the impeller is configured to increase a velocity of the working fluid; and a diffuser positioned downstream of the impeller, wherein the diffuser is configured to receive the working fluid from the impeller, and the diffuser comprises: a plurality of first vanes, wherein the plurality of first vanes defines a plurality of first vane passages, and each first vane passage of the plurality of first vane passages is configured to receive the working fluid; and a plurality of second vanes, wherein each second vane of the plurality of second vanes is positioned within a respective first vane passage of the plurality of first vane passages, wherein each first vane of the plurality of first vanes comprises a first arc length, each second vane of the plurality of second vanes comprises a second arc length, and the first arc length is greater than the second arc length.

2. The screw compressor of claim 1, wherein the impeller is configured to direct the working fluid at least partially in a direction along the axis and at least partially in a radially outward direction, relative to the axis, and the diffuser is configured to direct the working fluid at least partially in the direction along the axis and at least partially in a radially inward direction, relative to the axis.

3. The screw compressor of claim 2, wherein the plurality of first vanes and the plurality of second vanes are configured to reduce a circumferential flow component of the working fluid and direct flow of the working fluid in the direction along the axis.

4. The screw compressor of claim 1, wherein the diffuser comprises a diffuser inlet and a diffuser outlet, each first vane of the plurality of first vanes comprises a firstleading edge portion configured to receive the working fluid from the diffuser inlet and a first trailing edge portion, downstream of the first leading edge portion, configured to direct the working fluid toward the diffuser outlet, the respective first leading edge portion of at least one first vane of the plurality of first vanes extends at a first angle, relative to the axis, and the respective first trailing edge portion of the at least one first vane of the plurality of first vanes extends at a second angle, relative to the axis, and the first angle is different than the second angle.

5. The screw compressor of claim 4, wherein the first angle is greater than the second angle.

6. The screw compressor of claim 4, wherein each second vane of the plurality of second vanes comprises a second leading edge portion and a second trailing edge portion downstream of the second leading edge portion, and the respective second leading edge portion of each second vane of the plurality of second vanes is positioned downstream of the respective first leading edge portion of each first vane of the plurality of first vanes.

7. The screw compressor of claim 1, wherein at least one second vane of the plurality of second vanes is positioned equidistantly between two first vanes of the plurality of first vanes relative to a circumferential direction extending about the axis, wherein the at least one second vane of the plurality of second vanes and one first vane of the two first vanes of the plurality of first vanes define a respective second vane passage.

8. The screw compressor of claim 1, wherein the diffuser comprises a hub and a shroud positioned radially outward of the hub, relative to the axis, the plurality of first vanes extend from the hub to the shroud, and the plurality of second vanes extends from the hub to the shroud.

9. The screw compressor of claim 1, comprising a motor configured to drive rotation of the impeller, wherein the diffuser is configured to discharge the working fluid along the axis and across the motor.

10. The screw compressor of claim 9, comprising a first screw rotor and a second screw rotor configured to cooperatively compress the working fluid, wherein the motor is configured to drive rotation of the first screw rotor, and the motor is positioned between the first screw rotor and the diffuser along the axis.

11. The screw compressor of claim 9, wherein the diffuser comprises a plurality of third vanes, wherein at least one third vane of the plurality of third vanes is positioned between a respective second vane of the plurality of second vanes and a respective first vane of the plurality of first vanes adjacent to the respective second vane of the plurality of second vanes, wherein the at least one third vane of the plurality of third vanes is different from the respective first vane of the plurality of first vanes and the respective second vane of the plurality of second vanes.

12. A diffuser for a compressor for a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system, wherein the diffuser comprises: a hub; a shroud; a plurality of first vanes extending between the hub and the shroud, wherein the plurality of first vanes, the hub, and the shroud define a plurality of first vane passages, and each first vane passage of the plurality of first vane passages is configured to receive a flow of working fluid; and a plurality of second vanes extending between the hub and the shroud, wherein a second vane of the plurality of second vanes is positioned within a respective first vane passage of the plurality of first vane passages, wherein the second vane of the plurality of second vanes and a first vane of the respective first vane passage define a second vane passage configured to discharge the flow of working fluid at least partially across one or more motor components of the compressor, wherein each first vane of the plurality of first vanes comprises a first arc length and each second vane of the plurality of second vanes comprises a second arc length, and the first arc length is greater than the second arc length.

13. The diffuser of claim 12, wherein each first vane of the plurality of first vanes comprises a first trailing edge portion adjacent to a diffuser outlet and a first leading edge portion extending from the first trailing edge portion towards a diffuser inlet, wherein the first leading edge portion extends from the first trailing edge portion at first angle and wherein each second vane of the plurality of second vanes comprises a second trailing edge portion adjacent to the diffuser outlet and a second leading edge portion extending from the second trailing edge portion towards the diffuser inlet and downstream of the first leading edge portion, wherein the second leading edge portion extends from the second trailing edge portion at a second angle.

14. The diffuser of claim 13, wherein each second vane of the plurality of second vanes extends from the hub at a first angle and each second vane of the plurality of second vanes extends from the shroud at a second angle, wherein the first angle is different from the second angle.

15. The diffuser of claim 14, wherein the first angle or the second angle varies along the first arc length of each first vane of the plurality of first vanes.

16. The diffuser of claim 12, comprising a plurality of third vanes extending between the hub and the shroud, wherein at least one third vane of the plurality of third vanes is positioned between a respective second vane of the plurality of second vanes and a respective first vane of the plurality of first vanes.

17. The diffuser of claim 16, wherein each third vane of the plurality of third vanes comprises a third arc length, and the third arc length is less than the first arc length or the second arc length.

18. A screw compressor for a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system, wherein the screw compressor comprises: an intake portion, comprising:an impeller configured to rotate about an axis and configured to receive a flow of working fluid directed into the impeller along the axis, wherein the impeller is configured to increase a velocity of the flow of working fluid; and a diffuser coupled to and positioned downstream of the impeller, wherein the diffuser is configured to receive the flow of working fluid from the impeller, and the diffuser comprises: a plurality of first vanes, wherein the plurality of first vanes defines a plurality of first vane passages, and each first vane passage of the plurality of first vane passages is configured to receive the flow of working fluid; and a plurality of second vanes, wherein a second vane of the plurality of second vanes is positioned within a respective first vane passage of the plurality of first vane passages, wherein each first vane of the plurality of first vanes comprises a first arc length and each second vane of the plurality of second vanes comprises a second arc length, and the first arc length is greater than the second arc length; a motor portion positioned downstream of the intake portion, wherein at least one motor component of the motor portion is configured to receive the flow of working fluid from the diffuser; and one or more rotors positioned downstream of the motor portion, wherein the one or more rotors are configured to at least partially compress the flow of working fluid.

19. The screw compressor of claim 18, wherein the diffuser comprises a hub at a first radial location relative to the axis and a shroud at a second radial location relative to the axis, wherein the first radial location is radially below the second radial location, wherein each first vane of the plurality of first vanes extends between the hub and the shroud, and wherein each second vane of the plurality of second vanes extend between the hub and the shroud.

20. The screw compressor of claim 19, wherein each first vane of the plurality of first vanes comprises a first trailing edge portion adjacent to a diffuser outlet and a first leading edge portion extending from the first trailing edge portion towards a diffuser inlet,wherein each second vane of the plurality of second vanes comprises a second leading edge portion and a second trailing edge portion downstream of the second leading edge portion, and a respective second leading edge portion of each second vane of the plurality of second vanes is positioned downstream of the respective first leading edge portion of each first vane of the plurality of first vanes at a position that is in a range of 20% to 70% of the second arc length of each full vane of the plurality of second vanes.

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