DIFFUSER TUBE RESONATOR FOR REFRIGERANT COMPRESSORS

Abstract

A refrigerant compressor includes an impeller rotatable about an axis and a volute. A diffuser is axially between a first wall and a second wall, and radially between an outlet of the impeller and the volute. A diffuser plate provides the second wall, which includes a plurality of quarter wave tubes, each of the plurality of quarter wave tubes including a cylindrical blind hole extending radially from the second wall.

Description

BACKGROUND

Refrigerant compressors are used to circulate refrigerant in a chiller via a refrigerant loop. Refrigerant loops are known to include a condenser, an expansion device, and an evaporator. The compressor compresses the fluid, which then travels to a condenser, which in turn cools and condenses the fluid. The refrigerant then goes to an expansion device, which decreases the pressure of the fluid, and to the evaporator, where the fluid is vaporized, completing a refrigeration cycle.

Many refrigerant compressors are centrifugal compressors and have an electric motor that drives at least one impeller to compress refrigerant. Refrigerant flows into the impeller in an axial direction, and is expelled radially from the impeller toward a diffuser. Within the diffuser, the refrigerant broadens and reduces its speed, resulting in an increase in pressure.

SUMMARY

In some aspects, the techniques described herein may relate to a refrigerant compressor, including: an impeller rotatable about an axis; a volute; a diffuser disposed, relative to the axis, axially between a first wall and a second wall, and radially between an outlet of the impeller and the volute; and a diffuser plate providing the second wall, the second wall including a plurality of quarter wave tubes, each of the plurality of quarter wave tubes including a cylindrical blind hole extending radially from the second wall.

In some aspects, the techniques described herein may relate to a refrigerant compressor, and the plurality of quarter wave tubes includes: a first series of circumferentially spaced quarter wave tubes; and a second series of circumferentially spaced quarter wave tubes radially outward of the first series.

In some aspects, the techniques described herein may relate to a refrigerant compressor, and the first series of quarter wave tubes have a first diameter, and the second series of quarter wave tubes have a second diameter greater than the second diameter.

In some aspects, the techniques described herein may relate to a refrigerant compressor, and the second series of quarter wave tubes have a greater depth than the first series of quarter wave tubes.

In some aspects, the techniques described herein may relate to a refrigerant compressor, and the plurality of quarter wave tubes includes: a third series of circumferentially spaced quarter wave tubes radially outward of the second series.

In some aspects, the techniques described herein may relate to a refrigerant compressor, and the plurality of quarter wave tubes includes: a fourth series of circumferentially spaced quarter wave tubes radially outward of the third series.

In some aspects, the techniques described herein may relate to a refrigerant compressor, and the third series of quarter wave tubes have a greater depth than at least one of the first series and the second series.

In some aspects, the techniques described herein may relate to a refrigerant compressor, and the diffuser plate is an annular disk.

In some aspects, the techniques described herein may relate to a refrigerant compressor, and the annular disk is received in a recess.

In some aspects, the techniques described herein may relate to a method, including: providing a diffuser plate radially between an outlet of an impeller and a volute, diffuser plate providing a second wall axially opposite a first wall of a diffuser, the second wall including a plurality of quarter wave tubes, each of the plurality of quarter wave tubes including a cylindrical blind hole extending radially from the second wall.

In some aspects, the techniques described herein may relate to a method, and the plurality of quarter wave tubes includes: a first series of circumferentially spaced quarter wave tubes; and a second series of circumferentially spaced quarter wave tubes radially outward of the first series.

In some aspects, the techniques described herein may relate to a method, and the first series of quarter wave tubes have a first diameter, and the second series of quarter wave tubes have a second diameter greater than the second diameter.

In some aspects, the techniques described herein may relate to a method, and the second series of quarter wave tubes have a greater depth than the first series of quarter wave tubes.

In some aspects, the techniques described herein may relate to a refrigerant system, including: a main refrigerant loop including a compressor, a condenser, an evaporator, and an expansion device, and the compressor includes: an impeller rotatable about an axis; a volute; a diffuser disposed, relative to the axis, axially between a first wall and a second wall, and radially between an outlet of the impeller and the volute; and a diffuser plate providing the second wall, the second wall including a plurality of quarter wave tubes, each of the plurality of quarter wave tubes including a cylindrical blind hole extending radially from the second wall.

In some aspects, the techniques described herein may relate to a system, and the plurality of quarter wave tubes includes: a first series of circumferentially spaced quarter wave tubes; and a second series of circumferentially spaced quarter wave tubes radially outward of the first series.

In some aspects, the techniques described herein may relate to a system, and the first series of quarter wave tubes have a first diameter, and the second series of quarter wave tubes have a second diameter greater than the second diameter.

In some aspects, the techniques described herein may relate to a system, and the second series of quarter wave tubes have a greater depth than the first series of quarter wave tubes.

In some aspects, the techniques described herein may relate to a system, and the plurality of quarter wave tubes includes: a third series of circumferentially spaced quarter wave tubes radially outward of the second series.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a refrigerant system.

FIG. 2 schematically illustrates a portion of a compressor.

FIG. 3 illustrates an example diffuser plate.

FIG. 4 schematically illustrates flow of refrigerant across the example diffuser plate.

FIG. 5 is a plot of simulation results of an example diffuser.

DETAILED DESCRIPTION

FIG. 1 illustrates a refrigerant system 10. The refrigerant system 10 includes a main refrigerant loop, or circuit, 12 in communication with a refrigerant compressor 14, a condenser 16, an evaporator 18, and an expansion device 20. This refrigerant system 10 may be used in a chiller, for example. In that example, a cooling tower may be in fluid communication with the condenser 16. While a particular example of the refrigerant system 10 is shown, this application extends to other refrigerant system configurations, including configurations that do not include a chiller. For instance, the main refrigerant loop 12 can include an economizer downstream of the condenser 16 and upstream of the expansion device 20.

FIG. 2 illustrates, in cross-section, a portion of the compressor 14. The compressor 14 includes an electric motor 22 having a stator 24 arranged radially outside of a rotor 26. The rotor 26 is connected to a shaft 28, which rotates to drive at least one compression stage 30 of the compressor 14, which in this example includes at least one impeller 32. The compressor 14 may include multiple compression stages.

The shaft 28 and impeller 32 are rotatable by the electric motor 22 about an axis A to compress refrigerant F. The terms axial, radial, and circumferential in this disclosure are used relative to the axis A. The shaft 28 may be rotatably supported by a plurality of bearing assemblies, which may be magnetic bearing assemblies.

During operation of the compressor 14, refrigerant F flows axially toward the impeller 32 and is expelled radially outwardly to a diffuser 34 downstream of the impeller 32. The diffuser 34 is a channel arranged axially between a first wall 36 and a second wall 38, and arranged radially between the outlet of the impeller 32 and a volute 40. The volute 40 may be in fluid communication with the condenser 16 or another compression stage of the compressor 14. Within the diffuser 34, refrigerant F expelled by the impeller 32 broadens and reduces in speed, resulting in an increase in pressure of the refrigerant F.

In some operational conditions of the compressor 14, the flow characteristics of the refrigerant F may create noise. Specifically, as refrigerant F flows through the diffuser 34, flow perturbation in the form of pressure waves are also introduced into the diffuser 34. The pressure waves will oscillate at a range of frequencies and can create noise. In this disclosure, the diffuser 34 includes features configured to attenuate that noise.

In some examples, as shown, at least part of the surface 38 may be provided by an annular diffuser plate 42 including a plurality of quarter wave tubes 44 formed therein. While the diffuser plate 42 including the quarter wave tubes 44 provide the second wall 38, it could be provided the first wall 36 in some examples. The diffuser plate 42 may be provided within a recess of the diffuser 34 as shown. The diffuser plate 42 may be disk shaped. The plurality of quarter wave tubes 44 may be provided at an upper surface of the disk. The plurality of quarter wave tubes 44 may extend from an exposed planar surface of the diffuser plate 42.

FIG. 3 illustrates an example diffuser plate 42. As shown, the plate 42 may include multiple radially spaced series of circumferentially spaced quarter wave tubes 44. The example quarter wave tubes 44 are not through-openings. Rather, refrigerant F enters and exits the quarter wave tubes 44 via the diffuser 34. The quarter wave tubes 44 may be machined into the wall 38. A first series 44A of circumferentially spaced quarter wave tubes 44 may be provided. A second series 44B of circumferentially spaced quarter wave tubes 44 may be provided radially outward of the first series 44A. A third series 44C of circumferentially spaced quarter wave tubes 44 may be provided radially outward of the second series 44B. A fourth series 44D of circumferentially spaced quarter wave tubes 44 may be provided radially outward of the third series 44C. A fifth series 44E of circumferentially spaced quarter wave tubes 44 may be provided radially outward of the fourth series 44D. A sixth series 44F of circumferentially spaced quarter wave tubes 44 may be provided radially outward of the fifth series 44E. The quarter wave tubes 44 in one or more of the series 44A, 44B, 44C, 44D, 44E, 44F may be equally circumferentially spaced from one another. The quarter wave tubes 44 within the same series may have the same diameter. The quarter wave tubes 44 within the same series may have the same depth.

As shown, in some examples, the quarter wave tubes in a particular series may have a smaller diameter than quarter waves tubes in one or more of the series radially outward of them. The quarter wave tubes in the series 44F may have a greater diameter than the quarter wave tubes in one or more of the series 44E, 44D, 44C, 44B, 44A. The quarter wave tubes in the series 44E may have a greater diameter than the quarter wave tubes in one or more of the series 44D, 44C, 44B, 44A. The quarter wave tubes in the series 44D may have a greater diameter than the quarter wave tubes in one or more of the series 44C, 44B, 44A. The quarter wave tubes in the series 44C may have a greater diameter than the quarter wave tubes in one or more of the series 44B, 44A. The quarter wave tubes in the series 44B may have a greater diameter than the quarter wave tubes in the series 44A. As shown in FIG. 4 for example, diameter Di3 is greater than diameter Di2, which is greater than diameter Di1. Other size relationships are contemplated.

In some examples, the quarter wave tubes 44 in a particular series may have a shallower depth relative to the second wall 38 than quarter waves tubes in one or more of the series radially outward of them. The quarter wave tubes in the series 44F may have a greater depth than the quarter wave tubes in one or more of the series 44E, 44D, 44C, 44B, 44A. The quarter wave tubes in the series 44E may have a greater depth than the quarter wave tubes in one or more of the series 44D, 44C, 44B, 44A. The quarter wave tubes in the series 44D may have a greater depth than the quarter wave tubes in one or more of the series 44C, 44B, 44A. The quarter wave tubes in the series 44C may have a greater depth than the quarter wave tubes in one or more of the series 44B, 44A. The quarter wave tubes in the series 44B may have a greater depth than the quarter wave tubes in the series 44A. As shown in FIG. 4 for example, depth De3 is greater than depth De2, which is greater than depth De1. Other size relationships are contemplated. Applicant has found that the diameter and depth of the quarter wave tubes 44 can be altered to target specific frequencies.

As illustrated schematically in FIG. 4, with continued reference to FIGS. 1-3, refrigerant flows radially outward across the wall 38. As shown, the example quarter wave tubes 44 are cylindrical blind holes. Each quarter wave tube 44 extends to a floor 50, such that refrigerant F enters and exits the quarter wave tubes 44 via the diffuser 34, before reaching the volute 40. These quarter wave tubes 44 reduce the acoustic noise of certain frequencies as refrigerant flow passes over them. Applicant has found that the depth of the tube 44 may be varied to target specific frequencies. Applicant has further found that, in some examples, using circular holes reduces acoustics in the flow no matter the direction of the flow passing through the refrigerant compressor's diffuser.

The examples disclosed herein decrease the acoustic level of the flow of a given centrifugal, refrigerant compressor system by attenuating specific acoustic frequencies in refrigerant inside the compressor through the usage of quarter wave tubes machined into the compressor's diffuser.

This series of tubes provide a resonator and can be machined and integrated into an existing refrigerant compressor's diffuser, directly after a first or second stage impeller. At these locations, the high velocity refrigerant that would normally continue towards the outlet of the compressor, will first pass through a modified diffuser. As the refrigerant passes through the modified diffuser, quarter wave tubes machined into the diffuser work to attenuate acoustic noise in the refrigerant flow at certain frequencies.

The results for an acoustic simulation an example disclosed herein can be seen in FIG. 5. This plot shows the performance of the resonator transmission loss at each frequency from 0-15,000 Hz. This plot shows that frequencies from 5,600 Hz to 7,600 Hz and 10,600 Hz to 12,800 Hz will experience at least a 15 dB reduction in acoustic noise. Because of the low flow area present in the diffuser of a compressor, this resonator is particularly effective at attenuating high frequency noise.

A refrigerant compressor according to one or more of the disclosed examples may be said to include an impeller rotatable about an axis and a volute. A diffuser is axially between a first wall and a second wall, and radially between an outlet of the impeller and the volute. A diffuser plate provides the second wall, which includes a plurality of quarter wave tubes, each of the plurality of quarter wave tubes including a cylindrical blind hole extending radially from the second wall.

A method according to one or more of the disclosed examples may be said to include providing a diffuser plate radially between an outlet of an impeller and a volute, diffuser plate providing a second wall axially opposite a first wall of a diffuser, the second wall including a plurality of quarter wave tubes, each of the plurality of quarter wave tubes including a cylindrical blind hole extending radially from the second wall.

Although the different examples are illustrated as having specific components, the examples of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the embodiments in combination with features or components from any of the other embodiments.

The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure.

Claims

1. A refrigerant compressor, comprising: an impeller rotatable about an axis;a volute;a diffuser disposed, relative to the axis, axially between a first wall and a second wall, and radially between an outlet of the impeller and the volute; anda diffuser plate providing the second wall, the second wall including a plurality of quarter wave tubes, each of the plurality of quarter wave tubes including a cylindrical blind hole extending radially from the second wall.

2. The refrigerant compressor of claim 1, wherein the plurality of quarter wave tubes includes: a first series of circumferentially spaced quarter wave tubes; anda second series of circumferentially spaced quarter wave tubes radially outward of the first series.

3. The refrigerant compressor of claim 2, wherein the first series of quarter wave tubes have a first diameter, and the second series of quarter wave tubes have a second diameter greater than the second diameter.

4. The refrigerant compressor of claim 2, wherein the second series of quarter wave tubes have a greater depth than the first series of quarter wave tubes.

5. The refrigerant compressor of claim 2, wherein the plurality of quarter wave tubes includes: a third series of circumferentially spaced quarter wave tubes radially outward of the second series.

6. The refrigerant compressor of claim 5, wherein the plurality of quarter wave tubes includes: a fourth series of circumferentially spaced quarter wave tubes radially outward of the third series.

7. The refrigerant compressor of claim 5, wherein the third series of quarter wave tubes have a greater depth than at least one of the first series and the second series.

8. The refrigerant compressor of claim 1, wherein the diffuser plate is an annular disk.

9. The refrigerant compressor of claim 8, wherein the annular disk is received in a recess.

10. The refrigerant compressor of claim 1, wherein the plurality of quarter wave tubes includes: a first series of circumferentially spaced quarter wave tubes; anda second series of circumferentially spaced quarter wave tubes radially outward of the first series;wherein the first series of quarter wave tubes have a first diameter, and the second series of quarter wave tubes have a second diameter greater than the second diameter, andthe second series of quarter wave tubes have a greater depth than the first series of quarter wave tubes.

11. The refrigerant compressor of claim 10, wherein the diffuser plate is an annular disk.

12. A method, comprising: providing a diffuser plate radially between an outlet of an impeller and a volute, diffuser plate providing a second wall axially opposite a first wall of a diffuser, the second wall including a plurality of quarter wave tubes, each of the plurality of quarter wave tubes including a cylindrical blind hole extending radially from the second wall.

13. The method of claim 12, wherein the plurality of quarter wave tubes includes: a first series of circumferentially spaced quarter wave tubes; anda second series of circumferentially spaced quarter wave tubes radially outward of the first series.

14. The method of claim 13, wherein the first series of quarter wave tubes have a first diameter, and the second series of quarter wave tubes have a second diameter greater than the second diameter.

15. The method of claim 13, wherein the second series of quarter wave tubes have a greater depth than the first series of quarter wave tubes.

16. A refrigerant system, comprising: a main refrigerant loop including a compressor, a condenser, an evaporator, and an expansion device, wherein the compressor includes: an impeller rotatable about an axis;a volute;a diffuser disposed, relative to the axis, axially between a first wall and a second wall, and radially between an outlet of the impeller and the volute; anda diffuser plate providing the second wall, the second wall including a plurality of quarter wave tubes, each of the plurality of quarter wave tubes including a cylindrical blind hole extending radially from the second wall.

17. The refrigerant system of claim 16, wherein the plurality of quarter wave tubes includes: a first series of circumferentially spaced quarter wave tubes; anda second series of circumferentially spaced quarter wave tubes radially outward of the first series.

18. The refrigerant system of claim 17, wherein the first series of quarter wave tubes have a first diameter, and the second series of quarter wave tubes have a second diameter greater than the second diameter.

19. The refrigerant system of claim 17, wherein the second series of quarter wave tubes have a greater depth than the first series of quarter wave tubes.

20. The refrigerant system of claim 17, wherein the plurality of quarter wave tubes includes: a third series of circumferentially spaced quarter wave tubes radially outward of the second series.