Refrigerant compressor with radial-axial-radial arranged impellers

Abstract

A refrigerant compressor includes a shaft rotatable about an axis. A first radial stage includes a first radial impeller coupled to the shaft. An axial stage is fluidly downstream of the first radial stage includes an axial stage impeller coupled to the shaft. A second radial stage fluidly downstream of the axial stage includes a second radial impeller coupled to the shaft.

Description

REFRIGERANT COMPRESSOR WITH RADIAL-AXIAL-RADIAL ARRANGED IMPELLERSCROSS-REFERENCED TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No. 63 / 606,770, which was filed on December 6, 2023.BACKGROUND

[0002] 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.

[0003] Many refrigerant compressors are centrifugal compressors and have an electric motor that drives at least one impeller to compress refrigerant. Fluid flows into the impeller in an axial direction, and is expelled radially from the impeller. The fluid is then directed downstream for use in the chiller system.SUMMARY

[0004] In some aspects, the techniques described herein relate to a refrigerant compressor, including a shaft rotatable about an axis. A first radial stage includes a first radial impeller coupled to the shaft. An axial stage fluidly downstream of the first radial stage includes an axial stage impeller coupled to the shaft. A second radial stage fluidly downstream of the axial stage includes a second radial impeller coupled to the shaft.

[0005] In some aspects, the techniques described herein relate to a refrigerant compressor, including: a U-shaped return channel fluidly between the first radial stage and the axial stage.

[0006] In implementations, the axial stage includes an axial stage stator.

[0007] In implementations, the first radial stage is configured such that refrigerant flows parallel to the axis when entering the first radial impeller and in a radially outward direction when exiting the first radial impeller.

[0008] In some aspects, the techniques described herein relate to a refrigerant compressor, including a return channel fluidly downstream of the first radial impeller.

[0009] In implementations, the return channel is curved to smoothly redirect the refrigerant back radially inward and axially toward the axial stage.

[0010] In implementations, the axial stage is configured such that refrigerant enters the axial stage impeller in a first direction and exits an axial stage stator in a second direction, and the first direction and the second direction are within 30 degrees from parallel to the axis.

[0011] In some aspects, the techniques described herein relate to a refrigerant compressor, the first direction and the second direction are within 10 degrees from parallel to the axis.

[0012] In some aspects, the techniques described herein relate to a refrigerant compressor, including a volute, and the second radial stage is configured such that the second radial impeller receives refrigerant flowing in the second direction and directs the refrigerant radially outward to the volute.

[0013] In some aspects, the techniques described herein relate to a refrigerant compressor, including a housing, and the first radial stage, axial stage, and second radial stage are disposed within the housing.

[0014] In some aspects, the techniques described herein relate to a refrigerant compressor, including a shaft rotatable about an axis, a return channel, and a volute. A first radial stage includes a first radial impeller coupled to the shaft configured to receive refrigerant flowing in a first direction and direct the refrigerant in a second direction to the return channel, and the return channel is configured to direct the refrigerant in a third direction. An axial stage fluidly downstream of the first radial stage includes an axial stage impeller coupled to the shaft, and the axial stage is configured to receive the refrigerant flowing in a fourth direction and output the refrigerant flowing in a fifth direction. A second radial stage fluidly downstream of the axial stage includes a second radial impeller coupled to the shaft and configured to direct the refrigerant in a sixth direction to the volute. The first, fourth, and fifth directions are within 30 degrees of parallel to the axis, and the second, third, and sixth directions are within 30 degrees of perpendicular to the axis.

[0015] In implementations, the first, fourth, and fifth directions are within 10 degrees of parallel to the axis.

[0016] In implementations, the second, third, and sixth directions are within 10 degrees of perpendicular to the axis.

[0017] In implementations, the second direction is substantially radially outward, and the third direction is substantially radially inward.

[0018] In some aspects, the techniques described herein relate to a refrigerant compressor, including a housing, and the first radial stage, axial stage, and second radial stage are disposed within the housing.

[0019] In implementations, the return channel is U-shaped.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 schematically illustrates a refrigerant system.

[0021] Figure 2 illustrates an example compressor.

[0022] Figure 3 illustrates a side view of the example compressor of Figure 2.

[0023] Figure 4 schematically illustrates refrigerant flow through the example compressor of Figures 2 and 3.DETAILED DESCRIPTION

[0024] This disclosure relates generally to refrigerant compressors, and more particularly to compressors having an axial stage between two radial stages. The systems and methods disclosed herein have been found to increase efficiency and pressure ratio without substantially increasing size of the compressor.

[0025] Figure 1 illustrates a refrigerant system 10. The refrigerant system 10 includes a main refrigerant loop, or circuit, 12 in communication with a 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

[0026] Figure 2 illustrates an example refrigerant compressor 14 according to this disclosure. The example compressor 14 includes a first radial stage 22, and axial stage 24, and a second radial stage 26. The axial stage 24 is downstream of the first radial stage 22 with respect to refrigerant flow through the compressor 14. The second radial stage 26 is downstream of the axial stage 24 with respect to refrigerant flow through the compressor 14. The axial stage 24 is positioned axially between the first radial stage 22 and the second radial stage 26. In some examples, the axial stage 24 may be spaced from the second radial stage 26.

[0027] The first radial stage 22 includes an impeller 28, the axial stage 24 includes an impeller 30, and the second radial stage 26 includes an impeller 32. A volute 33 surrounds the second radial stage 26. The described stages 22, 24, 26 are each housed within the same housing 35 of the compressor 14. The housing 35 may be provided by one or more structures. In some examples, as shown, the compressor 14 has a single volute 33.

[0028] When the refrigerant flows through the impellers 28, 30, 32 the blades of the impellers 28, 30, 32 force the flow speed to increase and thus the flow kinetic energy increases, resulting in a pressure increase.

[0029] Figure 3 illustrates a side view of the example compressor 14. In some examples, as shown, the impellers 28, 30, 32 are each coupled to the shaft 34 rotatable about the axis A via a motor (not shown). The axial stage 24 includes an axial stage stator 36 axially between the impeller 30 and the impeller 32 with respect to the axis A. The example stator 36 is downstream of the impeller 30 and upstream of the impeller 32. The impeller 30 and the stator 36 may be substantially axially central on the shaft 34 in some examples as shown. In some examples, the axial stage 24 could include more than one impeller or stator.

[0030] Figure 4 schematically illustrates the flow path of refrigerant through the example compressor 14 of Figures 2 and 3. Refrigerant flows parallel to the axis A in the direction Fi from left to right as shown in the Figure and then through the impeller 28, where it is then directed radially outward in the direction FT to a return channel 40. In some examples, the flow Fi is within 30 degrees of parallel to the axis A. In some examples, the flow Fi is within 10 degrees of parallel to the axis A. The return channel 40 is curved to smoothly redirect the refrigerant back radially inward in the direction F3, which is substantially opposite the direction FT in some examples. The return channel 40 also guides the refrigerant to flow axiallytoward the axial stage as it makes its radial turn. In some examples, as shown, the return channel 40 is U-shaped.

[0031] After exiting the return channel 40, the refrigerant is then directed to turn to flow substantially parallel to the axis A in the direction F4, then flowing through the impeller 30 and the stator 36, exiting the stator 36 in the direction F5. Refrigerant exits the impeller 30 and then flows across the stator 36. In some examples, the flows F4 and F5 are within 30 degrees of parallel to the axis A. In some examples, flows F4 and F5 are within 10 degrees of parallel to the axis A. After exiting the stator 36, refrigerant then flows to and through the impeller 32, where it is then directed radially outward in the direction Fe to the volute 33.

[0032] In some examples, as shown, the direction Fi is substantially the same (± 30 degrees) as the directions F4 and / or F5. In some examples, as shown, the direction FT is substantially the same (± 30 degrees) as the direction Fe. In some examples, as shown, the direction F2 is substantially opposite the direction F3. In some examples, as shown, the continuous path including each direction Fi, F2, F , F4, F5, Fe is within the housing 35. In some examples, as shown, the directions F2, F3, Fe are perpendicular to the axis A. In some examples, the directions F2, F3, Fe are within 30 degrees of perpendicular to the axis A. In some examples, the directions F2, F3, Fe are within 10 degrees of perpendicular to the axis A. The flow is shown schematically through the upper portion of the cross section of the compressor 14, but the compressor 14 would essentially include the same flow reflected about its central longitudinal axis A.

[0033] Comparing to prior art two radial stage compressors, Applicant has found that the addition of the axial stage increases the overall machine pressure without increasing the machine size significantly. The increased machine pressure enables the machine to be applied in the high pressure required applications.

[0034] A refrigerant compressor according to one or more disclosed examples may be said to include a shaft rotatable about an axis. A first radial stage includes a first radial impeller coupled to the shaft. An axial stage fluidly downstream of the first radial stage includes an axial stage impeller coupled to the shaft. A second radial stage fluidly downstream of the axial stage includes a second radial impeller coupled to the shaft.

[0035] In implementations, a U-shaped return channel may be fluidly between the first radial stage and the axial stage. In implementations, the axial stage includes an axial stagestator. In implementations, the first radial stage is configured such that refrigerant flows parallel to the axis when entering the first radial impeller and in a radially outward direction when exiting the first radial impeller.

[0036] In implementations, the return channel is curved to smoothly redirect the refrigerant back radially inward and axially toward the axial stage. In implementations, the axial stage is configured such that refrigerant enters the axial stage impeller in a first direction and exits an axial stage stator in a second direction, and the first direction and the second direction are within 30 degrees from parallel to the axis. In implementations, the first direction and the second direction are within 10 degrees from parallel to the axis.

[0037] In implementations, a volute may be included, and the second radial stage is configured such that the second radial impeller receives refrigerant flowing in the second direction and directs the refrigerant radially outward to the volute.

[0038] In implementations, the first radial stage, axial stage, and second radial stage are disposed within a common housing.

[0039] A refrigerant compressor according to one or more disclosed examples may be said to include a shaft rotatable about an axis, a return channel, and a volute. A first radial stage includes a first radial impeller coupled to the shaft configured to receive refrigerant flowing in a first direction and direct the refrigerant in a second direction to the return channel, and the return channel is configured to direct the refrigerant in a third direction. An axial stage fluidly downstream of the first radial stage includes an axial stage impeller coupled to the shaft, and the axial stage is configured to receive the refrigerant flowing in a fourth direction and output the refrigerant flowing in a fifth direction. A second radial stage fluidly downstream of the axial stage includes a second radial impeller coupled to the shaft and configured to direct the refrigerant in a sixth direction to the volute. The first, fourth, and fifth directions are within 30 degrees of parallel to the axis, and the second, third, and sixth directions are within 30 degrees of perpendicular to the axis.

[0040] In implementations, the first, fourth, and fifth directions are within 10 degrees of parallel to the axis. In implementations, the second, third, and sixth directions are within 10 degrees of perpendicular to the axis. In implementations, the second direction is substantially radially outward, and the third direction is substantially radially inward. Inimplementations the first radial stage, axial stage, and second radial stage are disposed within a common housing. In implementations, the return channel is U-shaped.

[0041] 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.

[0042] 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

CLAIMSWhat is claimed is:

1. A refrigerant compressor, comprising: a shaft rotatable about an axis; a first radial stage including a first radial impeller coupled to the shaft; an axial stage fluidly downstream of the first radial stage including an axial stage impeller coupled to the shaft; and a second radial stage fluidly downstream of the axial stage and including a second radial impeller coupled to the shaft.

2. The refrigerant compressor of claim 1, comprising: a U-shaped return channel fluidly between the first radial stage and the axial stage.

3. The refrigerant compressor of claim 1, wherein the axial stage includes an axial stage stator.

4. The refrigerant compressor of claim 1, wherein the first radial stage is configured such that refrigerant flows parallel to the axis when entering the first radial impeller and in a radially outward direction when exiting the first radial impeller.

5. The refrigerant compressor of claim 4, comprising a return channel fluidly downstream of the first radial impeller.

6. The refrigerant compressor of claim 5 , wherein the return channel is curved to smoothly redirect the refrigerant back radially inward and axially toward the axial stage.

7. The refrigerant compressor of claim 6, wherein the axial stage is configured such that refrigerant enters the axial stage impeller in a first direction and exits an axial stagestator in a second direction, and the first direction and the second direction are within 30 degrees from parallel to the axis.

8. The refrigerant compressor of claim 7, the first direction and the second direction are within 10 degrees from parallel to the axis.

9. The refrigerant compressor of claim 7, comprising a volute, wherein the second radial stage is configured such that the second radial impeller receives refrigerant flowing in the second direction and directs the refrigerant radially outward to the volute.

10. The refrigerant compressor of claim 1, comprising a volute, wherein the second radial stage is configured such that the second radial impeller directs refrigerant radially outward to the volute.

11. The refrigerant compressor of claim 1, comprising a housing, wherein the first radial stage, axial stage, and second radial stage are disposed within the housing.

12. A refrigerant compressor, comprising: a shaft rotatable about an axis; a return channel; a volute; a first radial stage including a first radial impeller coupled to the shaft configured to receive refrigerant flowing in a first direction and direct the refrigerant in a second direction to the return channel, wherein the return channel is configured to direct the refrigerant in a third direction; an axial stage fluidly downstream of the first radial stage including an axial stage impeller coupled to the shaft, wherein the axial stage is configured to receive the refrigerant flowing in a fourth direction and output the refrigerant flowing in a fifth direction; and a second radial stage fluidly downstream of the axial stage and including a second radialimpeller coupled to the shaft and configured to direct the refrigerant in a sixth direction to the volute, wherein the first, fourth, and fifth directions are within 30 degrees of parallel to the axis, and the second, third, and sixth directions are within 30 degrees of perpendicular to the axis.

13. The refrigerant compressor of claim 12, wherein the first, fourth, and fifth directions are within 10 degrees of parallel to the axis.

14. The refrigerant compressor of claim 12, wherein the second, third, and sixth directions are within 10 degrees of perpendicular to the axis.

15. The refrigerant compressor of claim 12, wherein the second direction is substantially radially outward, and the third direction is substantially radially inward.

16. The refrigerant compressor of claim 12, comprising a housing, wherein the first radial stage, axial stage, and second radial stage are disposed within the housing.

17. The refrigerant compressor of claim 12, wherein the return channel is U-shaped.

18. The refrigerant compressor of claim 12, wherein the first, fourth, and fifth directions are within 10 degrees of parallel to the axis; the second, third, and sixth directions are within 10 degrees of perpendicular to the axis; and the second direction is substantially radially outward, and the third direction is substantially radially inward.

19. The refrigerant compressor of claim 18, comprising a housing, wherein the first radial stage, axial stage, and second radial stage are disposed within the housing.

20. The refrigerant compressor of claim 18, wherein the return channel is U-shaped.

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