Refrigerant compressor including a slotted diffuser

Abstract

A refrigerant compressor according to example aspects of the present disclosure includes, among other things, a diffuser including a recess configured to resist backflow of refrigerant. For example, the compressor is used in a heating, ventilation, and air conditioning (HVAC) chiller system.

Description

[0001] Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 120,837, filed December 3, 2020, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to a refrigerant compressor including a slotted diffuser. The compressor is used, for example, in a heating, ventilation, and air conditioning (HVAC) chiller system. BACKGROUND

[0004] Refrigerant compressors are used to circulate a refrigerant through a refrigerant loop in a chiller. It is known that the refrigerant loop includes a condenser, an expansion device, and an evaporator. The compressor compresses a fluid, which in turn travels to the condenser, which in turn cools and condenses the fluid. The refrigerant then flows to the expansion device, which reduces the pressure of the fluid, and to the evaporator, where the fluid is vaporized, completing the refrigeration cycle.

[0005] Many refrigerant compressors are centrifugal compressors and have an electric motor that drives at least one impeller to compress the refrigerant. The refrigerant flows into the impeller in an axial direction and is discharged from the impeller in a radial direction toward a diffuser. Within the diffuser, the refrigerant widens and reduces its velocity, resulting in an increase in pressure. SUMMARY

[0006] A refrigerant compressor according to one exemplary aspect of the present disclosure includes, among other things, a diffuser including a slot configured to resist backflow of the refrigerant.

[0007] In another embodiment, the slot is a recess formed in a wall of the diffuser.

[0008] In another embodiment, the refrigerant compressor includes an impeller and a volute, and the diffuser is located radially between the impeller and the volute.

[0009] In another embodiment, each of the slots includes a radially inner end proximate the impeller and a radially outer end proximate the volute, and is arranged such that the radially outer end is spaced circumferentially from the radially inner end.

[0010] In another embodiment, each slot includes a first curved sidewall extending from the radially inner end to the radially outer end and a second curved sidewall extending from the radially inner end to the radially outer end.

[0011] In another embodiment, the depth of each of the slots is variable along the length of the respective slot.

[0012] In another embodiment, each of the grooves has a maximum depth at a point approximately midway between a radially inner end and a radially outer end.

[0013] In another embodiment, each of the grooves has a depth that gradually decreases from the maximum depth toward both the radially inner end and the radially outer end.

[0014] In another embodiment, each of the grooves is a first type of groove, the diffuser includes a plurality of a second type of groove, and each of the second type of groove is a circumferentially extending groove that connects adjacent first type of grooves.

[0015] In another embodiment, each of the first type of grooves has a depth that is variable in a radial direction when viewed in cross-section.

[0016] In another embodiment, each of the first type of grooves is sloped so as to be deeper at a radially inward location outside of the second type of groove, and each of the first type of grooves is sloped so as to be deeper at a radially outward location inside of the second type of groove.

[0017] In another embodiment, the second type of groove is sloped so as to be deeper at a radially inward location.

[0018] In another embodiment, the diffuser includes a first wall and a second wall opposite the first wall, and one or both of the first wall and the second wall includes the grooves.

[0019] A refrigerant system according to one example aspect of the disclosure includes, among other things, a condenser, an evaporator, an expansion device, and a refrigerant compressor. The refrigerant compressor includes a diffuser including grooves configured to resist backflow of refrigerant.

[0020] In another embodiment, the refrigerant compressor includes an impeller and a volute, the diffuser is located radially between the impeller and the volute, and the grooves are recesses formed in a wall of the diffuser.

[0021] In another embodiment, each of the grooves includes a radially inner end adjacent the impeller, a radially outer end adjacent the volute and arranged such that the radially outer end is spaced apart from the radially inner end in a circumferential direction, a first curved sidewall extending from the radially inner end to the radially outer end, and a second curved sidewall extending from the radially inner end to the radially outer end.

[0022] In another embodiment, a depth of each of the grooves is variable along a length of the respective groove.

[0023] In another embodiment, each of the recesses has a maximum depth at a point approximately midway between a radially inner end and a radially outer end.

[0024] In another embodiment, each of the recesses is a first type of recess, the diffuser includes a plurality of second type of recesses, and each of the second type of recesses is a circumferentially extending recess connecting adjacent recesses of the first type.

[0025] In another embodiment, radially outward of the second type of recesses, each of the first type of recesses is sloped deeper at a radially inward location, and radially inward of the second type of recesses, each of the first type of recesses is sloped deeper at a radially outward location. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A refrigerant system is schematically illustrated.

[0027] Figure 2 A portion of a compressor is schematically illustrated.

[0028] Figure 3A is a perspective view of a portion of an example diffuser relative to a volute arrangement.

[0029] Figure 3B is a close-up view of a portion of Figure 3A

[0030] Figure 4A is a perspective view of a portion of another example diffuser relative to a volute arrangement.

[0031] Figure 4B is a close-up view of a portion of Figure 4A

[0032] is a cross-sectional view of the example diffuser and volute taken along line 4C-4C in Figure 4C Figure 4B DETAILED DESCRIPTION

[0033] Figure 1 A refrigerant system 10 is illustrated. Such a refrigerant system 10 includes a primary refrigerant loop or circuit 12 in communication with a refrigerant compressor 14, a condenser 16, an evaporator 18, and an expansion device 20. For example, such a refrigerant system 10 can be used in a chiller. In this example, a cooling tower can be in fluid communication with the condenser 16. Although a particular example of a refrigerant system 10 is shown, the present application is extendable to other refrigerant system configurations, including configurations that do not contain a chiller. For example, the primary refrigerant loop 12 can include an economizer downstream of the condenser 16 and upstream of the expansion device 20. ​​​

[0034] Figure 2 A portion of the compressor 14 is illustrated in cross-section. The compressor 14 includes an electric motor 22 having a stator 24 disposed radially outward of a rotor 26. The rotor 26 is connected to a shaft 28 that 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 can include multiple compression stages.

[0035] The shaft 28 and impeller 32 can be rotated about an axis A by the electric motor 22 to compress refrigerant F. The terms axial, radial, and circumferential in this disclosure are used with respect to the axis A. The shaft 28 can be rotatably supported by a plurality of bearing assemblies, which can be magnetic bearing assemblies.

[0036] During operation of the compressor 14, refrigerant F flows axially toward the impeller 32 and is discharged radially outward to a diffuser 34 downstream of the impeller 32. The diffuser 34 is a passage disposed axially between a first wall 36 and a second wall 38 and radially between an outlet of the impeller 32 and a volute 40. The volute 40 can be in fluid communication with the condenser 16 or another compression stage of the compressor 14. Within the diffuser 34, the refrigerant F discharged by the impeller 32 widens and decreases in velocity, resulting in an increase in pressure of the refrigerant F.

[0037] In some operating conditions of the compressor 14, such as when the compressor 14 is operating at a relatively low speed and / or mass flow rate, the compressor 14 can experience an undesirable condition known as surge. Surge refers to a condition in which the refrigerant F tends to reverse or flow backward within the compressor 14.

[0038] The diffuser 34 in this disclosure is configured to resist such backflow of the refrigerant F within the diffuser 34, and in turn the diffuser 34 resists surge conditions and expands the useful operating range of the compressor 14. In one example, one or both of the first wall 36 and the second wall 38 includes a plurality of grooves. The grooves are recesses formed in the first wall 36 and / or the second wall 38. The first wall 36 and / or the second wall 38 can include a plurality of similarly arranged grooves spaced circumferentially from one another about the axis A. Further, each of the first wall 36 and / or the second wall 38 can include more than one type of groove.

[0039] Figure 3A and Figure 3B A first arrangement of grooves 42 is illustrated in relation to the first wall 36. Figure 3A and Figure 3B The grooves 42 are illustrated from an opposite side of the first wall 36. Thus, the grooves 42 are in Figure 3A and Figure 3BThe recess 42 appears as a protrusion from the perspective of the first wall 36. However, from the perspective of the refrigerant F in the diffuser 34, the recess 42 is a depression in the first wall 36. In one example, the recess 42 is formed by stamping into a metal sheet that forms the first wall 36. The recess 42 can be formed using other techniques such as milling, casting, additive manufacturing, etc.

[0040] With specific reference Figure 3B , the recess 42 extends radially from a radially inner end 44 adjacent the outlet of the impeller 32 to a radially outer end 46 adjacent the volute 40. The recess 42 is bounded on a circumferential side by a first side wall 48 and a second side wall 50, which in this example are spaced apart a constant distance from each other circumferentially along the length of the recess 42. The first and second side walls 48, 50 are curved such that the radially inner end 44 is spaced apart circumferentially from the radially outer end 46. The curvature of the first and second side walls 48, 50 corresponds to the expected circumferential component of the refrigerant F exiting the impeller 32.

[0041] Further, the depth of the recess 42 relative to the adjacent surface of the first wall 36 is variable along the length of the recess 42 from the radially inner end 44 to the radially outer end 46. In particular, the recess 42 includes a maximum depth at a midpoint 52 that is approximately halfway between the radially inner end 44 and the outer end 46. As moving radially away from the midpoint 52, the depth of the recess 42 gradually decreases toward both the radially inner end 44 and the radially outer end 46, at which points the recess 42 merges into the first wall 36. This arrangement of the recess 42 passively resists backflow of the refrigerant F under conditions that would otherwise potentially lead to a surge condition by reducing vortex flow in the flow downstream of the impeller. Further, although shown with respect to the first wall 36, the second wall 38 can alternatively or additionally include recesses similar to those described with respect to the first wall 36. Figure 3A and Figure 3B recesses similar to those shown and described.

[0042] Figures 4A to 4C Another example arrangement of recesses is illustrated. In this example, the first wall 36 includes two different types of recesses. A first type of recess 54 is generally similar to the recess 42. A second type of recess 56 is a circumferentially extending recess that connects adjacent recesses 54 of the first type. Figure 4A and Figure 4B The recesses 54, 56 are illustrated from an opposite side of the first wall 36 as Figure 3A and 3B shown in FIGS. 1 1 and 12 such that the recesses 54, 56 appear as protrusions, however from the perspective of the refrigerant F in the diffuser 34, they are actually depressions.

[0043] The first type of groove 54 extends radially from a radially inner end 58 adjacent the outlet of the impeller 32 to a radially outer end 60 adjacent the volute 40. The groove 54 is bounded on circumferential sides by a first sidewall 62 and a second sidewall 64, which in this example are spaced apart from one another a substantially constant distance circumferentially along the length of the groove 54. The first sidewall 62 and the second sidewall 64 are curved such that the radially inner end 58 is spaced apart from the radially outer end 60 circumferentially. The curvature of the first sidewall 62 and the second sidewall 64 corresponds to the expected circumferential component of the refrigerant F exiting the impeller 32, which in this example is opposite the direction in Figure 3A and Figure 3B .

[0044] Further, the depth of the groove 54 relative to the adjacent surface of the first wall 36 is variable along the groove 54 from the radially inner end 58 to the radially outer end 60. In particular, the groove 54 includes a maximum depth at a midpoint 66, and the depth of the groove 54 gradually decreases toward both the radially inner end 58 and the radially outer end 60, at which points the groove 54 merges into the first wall 36.

[0045] Adjacent the midpoint 66, adjacent grooves 54 are connected by a groove 56. The groove 56 extends circumferentially about the axis A and allows fluid to flow between adjacent grooves 54. For example, groove 54A (which is one of the grooves 54) is connected to an adjacent groove 54B (which is one of the grooves 54) by a groove 56A (which is one of the grooves 56). The groove 56A extends from the first sidewall 62 of the groove 54A to the second sidewall of the groove 54B. The groove 56A contacts the sidewalls of the grooves 54A, 54B at the midpoints 66 of the grooves 54A, 54B.

[0046] As shown in Figure 4C , the radial dimension of the grooves 54 and the grooves 56 is variable when viewed in cross-section. For example, at a location radially outward of the groove 56A, the groove 54A is angled such that it is deeper at a radially inward location. Specifically, at a location radially outward of the groove 56A, the second sidewall 64 is shallower than the first sidewall 62. At a location radially inward of the groove 56A, the opposite is true, as can be seen with respect to the groove 54B, in which the second sidewall 64 is deeper than the first sidewall 62. The grooves 56 also have a variable depth in the radial direction. In Figure 4C , the groove 56A is angled such that it is deeper at a radially inward location. Figures 4A to 4C The groove arrangement in Figures 4A to 4CGROOVES

[0047] The described diffusers can be used with radial or mixed flow compression stages. The compressor can include one or more of the described diffusers at one or more compression stages.

[0048] It should be understood that the terms used above such as "axial" and "radial" are used with reference to the normal operating orientation of the compressor. Furthermore, these terms are used herein for explanatory purposes and should not be considered limiting for other purposes. Terms such as "generally," "approximately," and "about" are not intended to be unbounded terms, and should be construed as the term would be construed by one of ordinary skill in the art.

[0049] While different examples have specific components as illustrated in the figures, embodiments of the present disclosure are not limited to these particular combinations. Some of the components or features in one example can be used with features or components from another example. Furthermore, the various figures attached hereto do not necessarily depict the actual scale, proportions, or relative positions of the particular components and arrangements, but are provided merely for explanatory purposes.

[0050] Those of ordinary skill in the art will appreciate that the above-described embodiments are exemplary and non-limiting. That is, modifications to the disclosed embodiments will occur to those of ordinary skill in the art. Therefore, the following claims should be studied to determine the true scope and content of the disclosure.

Claims

1. A refrigerant compressor, comprising: A diffuser, the diffuser including grooves configured to resist refrigerant backflow; The refrigerant compressor includes an impeller and a volute. The diffuser is located radially between the impeller and the volute. Each groove includes: (i) a radially inner end portion adjacent to the impeller; (ii) a radially outer end portion adjacent to the volute and arranged such that the radially outer end portion is circumferentially spaced from the radially inner end portion; (iii) a first curved sidewall extending from the radially inner end portion to the radially outer end portion; and (iv) a second curved sidewall extending from the radially inner end portion to the radially outer end portion. The depth of each groove in the groove is variable along the length of the corresponding groove, and Each of the grooves has its maximum depth at the midpoint of the groove.

2. The refrigerant compressor according to claim 1, wherein, The groove is a recess formed in the wall of the diffuser.

3. The refrigerant compressor according to claim 1, wherein, The midpoint of each groove is located approximately midway between the radially inner end and the radially outer end.

4. The refrigerant compressor according to claim 3, wherein, The depth of each groove in the groove gradually decreases from the maximum depth toward both the radially inner end and the radially outer end.

5. The refrigerant compressor according to claim 3, wherein, The midpoint of each groove is located midway between the radially inner end and the radially outer end.

6. A refrigerant compressor, comprising: A diffuser, the diffuser including grooves configured to resist refrigerant backflow; The refrigerant compressor includes an impeller and a volute. The diffuser is located radially between the impeller and the volute. Each groove includes: (i) a radially inner end portion adjacent to the impeller; (ii) a radially outer end portion adjacent to the volute and arranged such that the radially outer end portion is circumferentially spaced from the radially inner end portion; (iii) a first curved sidewall extending from the radially inner end portion to the radially outer end portion; and (iv) a second curved sidewall extending from the radially inner end portion to the radially outer end portion. The depth of each groove in the groove is variable along the length of the corresponding groove, and Each of the grooves has its maximum depth at a point midway between the radially inner end and the radially outer end of the groove; Each of the grooves is a first type of groove. The diffuser includes a plurality of grooves of the second type, and In this context, each of the second-type grooves is a circumferentially extending groove that connects to an adjacent first-type groove.

7. The refrigerant compressor according to claim 6, wherein, The depth of each of the first type of grooves, when viewed in a cross-sectional view, is variable in the radial direction.

8. The refrigerant compressor according to claim 7, wherein: On the radially outer side of the second type of groove, each of the first type of grooves is inclined, thus becoming deeper at a radially inward position, and On the radially inner side of the second type of groove, each of the first type of grooves is inclined, thus being deeper at a radially outward position.

9. The refrigerant compressor according to claim 8, wherein, The second type of groove is inclined, thus being deeper in the radially inward position.

10. The refrigerant compressor according to claim 1, wherein: The diffuser includes a first wall and a second wall opposite to the first wall, and One of the first wall and the second wall includes the groove.

11. A refrigerant system comprising: The refrigerant compressor comprises a condenser, an evaporator, an expansion unit, and a refrigerant compressor, wherein the refrigerant compressor includes a diffuser with recesses configured to resist refrigerant backflow. The refrigerant compressor includes an impeller and a volute. The diffuser is located radially between the impeller and the volute. Each groove includes: (i) a radially inner end portion adjacent to the impeller; (ii) a radially outer end portion adjacent to the volute and arranged such that the radially outer end portion is circumferentially spaced from the radially inner end portion; (iii) a first curved sidewall extending from the radially inner end portion to the radially outer end portion; and (iv) a second curved sidewall extending from the radially inner end portion to the radially outer end portion. The depth of each groove in the groove is variable along the length of the corresponding groove, and Each of the grooves has its maximum depth at a point midway between the radially inner end and the radially outer end of the groove; Each of the grooves is a first type of groove. The diffuser includes a plurality of grooves of the second type, and In this context, each of the second-type grooves is a circumferentially extending groove that connects to an adjacent first-type groove.

12. The refrigerant system according to claim 11, wherein: On the radially outer side of the second type of groove, each of the first type of grooves is inclined, thus being deeper at a radially inward position, and On the radially inner side of the second type of groove, each of the first type of grooves is inclined, thus being deeper at a radially outward position.

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