Centrifugal compressor assembly and method

Patent metadata

Field	Value
Publication number	US-9353765-B2
Application number	US-3459408-A
Country	US
Kind code	B2
Filing date	Feb 20, 2008
Priority date	Feb 20, 2008
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive. Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor. Another embodiment of the centrifugal compressor assembly comprises an integrated inlet flow conditioning assembly comprising a flow conditioning nose, a plurality of inlet guide vanes and a flow conditioning body that positions inlet guide vanes to condition flow of refrigerant into an impeller to achieve a target approximately constant angle swirl distribution with minimal guide vane turning.

First claim

We claim:

1. An inlet flow conditioning assembly for use in a centrifugal compressor to control aerodynamic blockage, distribution, and swirl of a refrigerant, comprising:
a. an inlet flow conditioning housing positioned within the compressor the inlet flow conditioning housing upstream of an impeller housed in the compressor; said impeller having impeller blades with leading edges; the inlet flow conditioning housing forming a flow conditioning channel axially extending from a channel inlet to a channel outlet;
b. a flow conditioning body having a first body end with a first body end radius, an intermediate portion with a body radius and a second body end with a second body end radius; said flow conditioning body being substantially centrally positioned along a length of the flow conditioning channel; the flow conditioning body is arranged coincident to a flow conditioning nose at the first body end and coincident to the impeller hub of the impeller at the second body end, said flow conditioning body having a streamline curvature where the body radius relative to an axis of rotation of the impeller that exceeds a radius of the impeller hub and where the first body end radius and second body radius are less than the body radius;
c. a plurality of inlet guide vanes positioned between said channel inlet and channel outlet; said plurality of inlet guide vanes being rotatably mounted on a support shaft at a location along the flow conditioning body where the body radius relative to the axis of rotation of the impeller exceeds the radius of the impeller hub; and
d. a strut including a first strut end and a second strut end, the first strut end being attached at the flow conditioning nose and the second strut end being attached to the inlet flow conditioning housing, and the strut designed to have a substantially s-shape in a plane substantially parallel to the channel inlet,
wherein the flow conditioning body, the flow conditioning nose and the plurality of inlet guide vanes are axially spaced along and relative to the flow conditioning channel to condition the refrigerant in the flow conditioning channel such that leading edges of the plurality of inlet guide vanes, in a fully open position, are aligned with a primarily axial flow distribution of the refrigerant in the fluid conditioning channel at and upstream of the plurality of inlet guide vanes and the plurality of inlet guide vanes, in a fully open position, impart on the primarily axial flow distribution of refrigerant, from the leading edges of the plurality of inlet guide vanes to trailing edges of the plurality of inlet guide vanes, a non-zero target swirl distribution, in a range between about 0 degrees to about 20 degrees, on the refrigerant flowing into leading edges of the impeller blades.

2. The inlet flow conditioning assembly of claim 1 wherein the strut has a strut mean camber line aligned in a flow direction plane of the channel inlet.

3. The inlet flow conditioning assembly of claim 1 wherein the strut has a symmetric thickness distribution around a mean camber line of the strut in a flow direction plane of the channel inlet.

4. The inlet flow conditioning assembly of claim 1 wherein the ratio of maximum radius of the flow conditioning body to the radius of the impeller hub is about 2 to 1.

5. The inlet flow conditioning assembly of claim 1 wherein the second body intermediate portion has a radius extending from the axis of rotation of the impeller larger than the first body end radius and the third body end radius.

6. The inlet flow conditioning assembly of claim 1 wherein the plurality of inlet guide vanes have a shroud side edge surface shaped to conform to a surface curvature of the flow conditioning body.

7. The inlet flow conditioning assembly of claim 1 wherein the inlet flow conditioning housing has a depressed surface shape; the plurality of inlet guide vanes have a shroud side edge surface shape, said shroud side edge surface shape conforms to the depressed surface shape.

8. The inlet flow conditioning assembly of claim 7 wherein the shape of the shroud side edge surface of the plurality of inlet guide vanes and the shape of the depressed surface of the inlet flow conditioning housing are substantially spherical such that the shroud side edge surface of the plurality of inlet guide vanes nests in the depressed surface of the inlet flow conditioning housing.

9. The inlet flow conditioning assembly of claim 1 wherein the plurality of inlet guide vanes are cambered airfoils.

10. The inlet flow conditioning assembly of claim 1 wherein the plurality of inlet guide vanes are configured with a radially varying camber with a symmetrical thickness.

11. The inlet flow conditioning assembly of claim 1 wherein the plurality of inlet guide vanes are configured with a variable spanwise camber and arranged to impart greater than 0 to about 20 degrees of swirl upstream of the impeller with a minimum total pressure loss of the compressor after the refrigerant passes through the plurality of inlet guide vanes.

12. The inlet flow conditioning assembly of claim 11 wherein the plurality of inlet guide vanes are arranged to impart about a constant radial 12 degrees of swirl at the impeller.

13. The inlet flow conditioning assembly of claim 1 wherein the plurality of inlet guide vanes comprising a plurality of blades arranged in a fully open position with a leading edge of the plurality of blades aligned with a flow direction of the refrigerant and with a trailing edge of the plurality of blades having radially varying camber from a hub side to a shroud side of the plurality of inlet guide vanes such that the plurality of inlet guide vanes impart up to about 20 degree swirl upstream of the impeller with a minimum total pressure loss of the compressor through the plurality of inlet guide vanes.

14. The inlet flow conditioning assembly of claim 1 wherein the plurality of inlet guide vanes are positioned at a location on the flow conditioning body where the radius of the flow conditioning body extending from the axis of rotation of the impeller is largest along the flow conditioning body.

15. The inlet flow conditioning assembly of claim 1 wherein the inlet flow conditioning assembly is located downstream of a swirl reducer.

16. The inlet flow conditioning assembly of claim 15 wherein the swirl reducer comprises:
a flow conduit being positioned upstream of the compressor; a radial blade connected to the flow conduit and a suction pipe; the flow conduit and the radial blade forming a plurality of flow chambers having a center coincident with the suction pipe and being configured such that the refrigerant having a swirling flow upstream of the flow chambers has a substantially axial flow downstream of the flow chambers.

17. A method of controlling aerodynamic blockage, distribution and swirl of the refrigerant through a centrifugal compressor having a compressor housing, said compressor for compressing a refrigerant, comprising the steps of:
a. positioning an inlet flow conditioning assembly upstream of an impeller disposed within the compressor housing said inlet flow conditioning assembly further comprising:
i. an inlet flow conditioning housing positioned within the compressor the inlet flow conditioning housing upstream of an impeller housed in the compressor; said impeller having impeller blades with leading edges; the inlet flow conditioning housing forming a flow conditioning channel axially extending from a channel inlet to a channel outlet;
ii. a flow conditioning body having a first body end with a first body end rad

Assignees

• Haley Paul F
• James Rick T
• Trane Int Inc

Inventors

• Haley Paul F
• James Rick T

Classifications

• F25B2339/0242

  having tubular elements · CPC title

• F25B39/02

  Evaporators · CPC title

• F25B39/00

  Evaporators; Condensers · CPC title

• F25B1/10

  with multi-stage compression (with cascade operation F25B7/00) · CPC title

• F25B1/053

  of turbine type · CPC title