Suction pipe of centrifugal compressor

Abstract

The application provides a suction pipe of a centrifugal compressor, the centrifugal compressor has a suction port with a central axis, the suction pipe guides fluid from an upstream component into the centrifugal compressor, and the fluid enters the suction pipe in a direction substantially perpendicular to the central axis of the suction port. The suction pipe comprises an imaginary mid-section, a downstream interface connected with the centrifugal compressor, and an upstream interface connected with the upstream component. The central axis of the suction port of the centrifugal compressor is located on the mid-section, and the suction pipe has a shape symmetrical relative to the mid-section. The inner contour of the downstream interface is circular and connected with the suction port. The inner contour of the upstream interface comprises a first direction maximum span size D1 located on the mid-section and a second direction maximum span size D2 perpendicular to the mid-section, wherein D1 is greater than D2. Through the above arrangement of the upstream interface 228, the local loss can be maximally reduced while meeting the cylinder strength requirement of the evaporator.

Description

TECHNICAL FIELD

[0001] The present application relates to a suction pipe of a centrifugal compressor, and more particularly to a suction pipe of a refrigeration centrifugal compressor mainly applied to a large water chiller. BACKGROUND

[0002] A refrigeration centrifugal compressor used in a large water chiller makes refrigerant gas coming out of an evaporator obtain high speed through high-speed rotation of an impeller in the centrifugal compressor, and then delivers the refrigerant gas to a condenser to make the refrigerant perform a refrigeration cycle. A suction pipe of the centrifugal compressor in a bent pipe shape connects the evaporator with the impeller of the centrifugal compressor to make the refrigerant gas coming out of the evaporator enter the evaporator through the suction pipe. Since the suction pipe is in a bent pipe shape, the flow direction of the refrigerant gas is deflected in the process of entering the suction pipe from the evaporator and reaching the impeller of the centrifugal compressor. There is a pressure loss in the suction pipe of the centrifugal compressor of the prior art, thereby affecting the performance of the compressor. SUMMARY

[0003] According to a first aspect of the present application, a suction pipe of a centrifugal compressor is provided. The centrifugal compressor has a suction port with a central axis. The suction pipe guides fluid from an upstream component into the centrifugal compressor, the fluid entering the suction pipe in a direction substantially perpendicular to the central axis of the suction port. The suction pipe comprises an imaginary mid-section, a downstream interface connected to the centrifugal compressor, and an upstream interface connected to the upstream component. The central axis of the suction port of the centrifugal compressor is located on the mid-section. The suction pipe has a shape symmetrical with respect to the mid-section. An inner contour of the downstream interface is circular and connected to the suction port. An inner contour of the upstream interface comprises a first direction maximum cross dimension D1 located on the mid-section, and a second direction maximum cross dimension D2 perpendicular to the mid-section, wherein the first direction maximum cross dimension D1 is greater than the second direction maximum cross dimension D2.

[0004] According to the suction pipe of the centrifugal compressor of the first aspect, the upstream component is a cylindrical shape with a diameter D0, and the axis of the cylindrical shape is parallel to the central axis of the suction port. The first direction maximum cross dimension D1 and the second direction maximum cross dimension D2 of the inner contour of the upstream interface satisfy 0.55 < D1 / D0 < 0.7, and D2 < 0.5 x D1. A radius R6 of the inner contour of the downstream interface satisfies 0.43 < R6 / D1 < 0.57. 6max

[0005] According to the suction pipe of the centrifugal compressor of the first aspect, the suction pipe has a center line located on the mid-section. The center line is a spline curve, and the center line satisfies the following formula: ​Wherein, V1, V2, V3, V4 satisfy the following relationships: -7e7 < V1 < -6e7, 1100 < V2 < 1300, -2950 < V3 < -2750, 250 < V4 < 270.

[0006] The suction pipe of the centrifugal compressor according to the first aspect described above comprises an inlet section, an outlet section and a transition section. The upstream interface is an end face of the inlet section, the inlet section comprises a connecting part and a guiding part, the connecting part connects the suction pipe with the upstream component, and the connecting line of the inner contour of the guiding part and the inner contour of the connecting part intersects with the middle section at an inner intersection point and an outer intersection point. The downstream interface is an end face of the outlet section. The transition section connects the inlet section with the outlet section. The suction pipe comprises a first cross section, which passes through the inner intersection point and the outer intersection point and is perpendicular to the middle section. Between the first cross section and the downstream interface, the cross section of the inner contour of the suction pipe on the inlet section and the transition section is an ellipse with a long axis on the middle section.

[0007] The suction pipe of the centrifugal compressor according to the first aspect described above, between the first cross section and the downstream interface, the cross section of the inner contour of the inlet section and the outlet section of the suction pipe gradually decreases in the direction towards the downstream interface.

[0008] The suction pipe of the centrifugal compressor according to the first aspect described above, the cross section of the inner contour of the transition section of the suction pipe gradually increases and then gradually decreases in the direction towards the downstream interface.

[0009] The suction pipe of the centrifugal compressor according to the first aspect described above, four cross sections obtained by equally dividing the part of the suction pipe between the first cross section and the downstream interface along the center line into five parts are respectively a second cross section, a third cross section, a fourth cross section and a fifth cross section, wherein the fourth cross section is the largest cross section of the transition section. The included angle α6 between the downstream interface and the first cross section satisfies: 80° ≤ α6 ≤ 90°. The long axis radius R 1max and the short axis radius R 1min of the first cross section respectively satisfy: R 1max = 0.5 × D1, 0.9 < R 1min / R 1max < 0.95. The included angle α2 between the second cross section and the first cross section and the long axis radius R 2max and the short axis radius R 2min of the second cross section respectively satisfy: 0.1 < α2 / α6 < 0.15, 0.68 < R 2max / D1 < 0.78, 0.92 < R 2min / R 2max<0.98. An angle a3 of the third cross section with the first cross section and a major axis radius R 3max and a minor axis radius R 3min respectively satisfy: 0.25 3max / D1<0.76, 0.8 3min / R 3max <0.9. An angle a4 of the fourth cross section with the first cross section and a major axis radius R 4max and a minor axis radius R 4min respectively satisfy: 0.45 4max / D1<0.74, 0.84 4min / R 4max <0.92. An angle a5 of the fifth cross section with the first cross section and a major axis radius R 5max and a minor axis radius R 5min respectively satisfy: 0.7 5max / D1<0.6, 0.98 5min / R 5max <1.05.

[0010] The suction pipe of the centrifugal compressor according to the first aspect above, the cross section of the transition section gradually decreases in the direction towards the downstream interface.

[0011] The suction pipe of the centrifugal compressor according to the first aspect above, four cross sections equally dividing the portion of the suction pipe between the first cross section and the downstream interface along the center line are respectively a second cross section, a third cross section, a fourth cross section and a fifth cross section, wherein the fourth cross section is the largest cross section of the transition section. An angle a 16 of the downstream interface with the first cross section satisfies: 80° 16 ≤ 90°. A major axis radius R 11min and a minor axis radius R 12min of the first cross section respectively satisfy: R11max=0.5xD 11 , 0.9 12 / a 12 6, 0.1 16<0.15, 0.68 < R12max / D11 < 0.78, 0.92 < R12min / R12max < 0.98. The angle a of the third cross section with the first cross section and the major axis radius R13max and the minor axis radius R13min of the third cross section respectively satisfy: 0.25 < a < 0.35, 0.5 < R13max / D11 < 0.6, 0.8 < R13min / R13max < 0.9. 13 The angle a of the fourth cross section with the first cross section and the major axis radius R14max and the minor axis radius R14min of the fourth cross section respectively satisfy: 0.45 < a < 0.55, 0.5 < R14max / D11 < 0.6, 0.9 < R14min / R14max < 0.95. 13 The angle a of the fifth cross section with the first cross section and the major axis radius R15max and the minor axis radius R15min of the fifth cross section respectively satisfy: 0.7 < a < 0.8, 0.45 < R15max / D11 < 0.55, 0.9 < R15min / R15max < 0.95. 16 The angle a of the sixth cross section with the first cross section and the major axis radius R16max and the minor axis radius R16min of the sixth cross section respectively satisfy: 0.8 < a < 0.9, 0.5 < R16max / D11 < 0.6, 0.95 < R16min / R16max < 0.98. 14 The angle a of the seventh cross section with the first cross section and the major axis radius R17max and the minor axis radius R17min of the seventh cross section respectively satisfy: 0.9 < a < 1.0, 0.6 < R17max / D11 < 0.7, 0.98 < R17min / R17max < 0.99. 16 The angle a of the eighth cross section with the first cross section and the major axis radius R18max and the minor axis radius R18min of the eighth cross section respectively satisfy: 1.0 < a < 1.1, 0.7 < R18max / D11 < 0.8, 0.99 < R18min / R18max < 1.0. 15 The angle a of the ninth cross section with the first cross section and the major axis radius R19max and the minor axis radius R19min of the ninth cross section respectively satisfy: 1.1 < a < 1.2, 0.8 < R19max / D11 < 0.9, 1.0 < R19min / R19max < 1.05. 15 The angle a of the tenth cross section with the first cross section and the major axis radius R20max and the minor axis radius R20min of the tenth cross section respectively satisfy: 1.2 < a < 1.3, 0.9 < R20max / D11 < 1.0, 1.05 < R20min / R20max < 1.1. 16 The angle a of the eleventh cross section with the first cross section and the major axis radius R21max and the minor axis radius R21min of the eleventh cross section respectively satisfy: 1.3 < a < 1.4, 1.0 < R21max / D11 < 1.1, 1.1 < R21min / R21max < 1.2. 15max The angle a of the twelfth cross section with the first cross section and the major axis radius R22max and the minor axis radius R22min of the twelfth cross section respectively satisfy: 1.4 < a < 1.5, 1.1 < R22max / D11 < 1.2, 1.2 < R22min / R22max < 1.3. 11 The angle a of the thirteenth cross section with the first cross section and the major axis radius R23max and the minor axis radius R23min of the thirteenth cross section respectively satisfy: 1.5 < a < 1.6, 1.2 < R23max / D11 < 1.3, 1.3 < R23min / R23max < 1.4. 15min The angle a of the fourteenth cross section with the first cross section and the major axis radius R24max and the minor axis radius R24min of the fourteenth cross section respectively satisfy: 1.6 < a < 1.7, 1.3 < R24max / D11 < 1.4, 1.4 < R24min / R24max < 1.5. 15max The angle a of the fifteenth cross section with the first cross section and the major axis radius R25max and the minor axis radius R25min of the fifteenth cross section respectively satisfy: 1.7 < a < 1.8, 1.4 < R25max / D11 < 1.5, 1.5 < R25min / R25max < 1.6.

[0012] According to a second aspect of the present application, the present application provides a centrifugal compressor, comprising the suction pipe according to the first aspect described above. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1A is a perspective view of a water chiller using the suction pipe of the centrifugal compressor of the present application;

[0014] Figure 1B is a simplified left view schematic of the water chiller shown in Figure 1A

[0015] Figure 2A is a front perspective view of the first embodiment of the suction pipe of the centrifugal compressor of the present application;

[0016] Figure 2B is a rear perspective view of the suction pipe of the centrifugal compressor shown in Figure 2A

[0017] is a front view of the inner contour of the suction pipe of the centrifugal compressor shown in Figure 2C Figure 2A

[0018] Figure 2D ​​​is Figure 2A left view of the inner profile of the suction pipe of the centrifugal compressor shown in

[0019] Figure 2E is Figure 2D schematic view of a first cross section in

[0020] Figure 2F is Figure 2D schematic view of a second cross section in

[0021] Figure 2G is Figure 2D schematic view of a third cross section in

[0022] Figure 2H is Figure 2D schematic view of a fourth cross section in

[0023] Figure 2I is Figure 2D schematic view of a fifth cross section in

[0024] Figure 2J is Figure 2A schematic view of the inner profile of the downstream interface of the suction pipe for a centrifugal compressor shown in

[0025] Figure 3A is a schematic view showing the fluid flow condition of the suction pipe of a comparative example in use;

[0026] Figure 3B is a schematic view showing the fluid flow condition of the first embodiment of the suction pipe for a centrifugal compressor of the present application in use;

[0027] Figure 3C shows the velocity vector plot in the suction pipe of the comparative example shown in Figure 3A

[0028] Figure 3D shows the velocity vector plot in the suction pipe of the present application shown in Figure 3B

[0029] Figure 3E shows the velocity vector plot at the downstream interface of the suction pipe of the comparative example shown in Figure 3A

[0030] Figure 3F shows the velocity vector plot at the downstream interface of the suction pipe of the present application shown in Figure 3B

[0031] Figure 3G shows the velocity vector plot at the downstream interface of the suction pipe of the present application shown in​​​​Figure 3A The vortex intensity diagram at the downstream interface of the intake duct of the comparative example shown is obtained using the CFD method;

[0032] Figure 3H Shows the Figure 3B The vortex intensity diagram at the downstream interface of the intake duct of the present application is obtained by using the CFD method;

[0033] Figure 4A is a front perspective view of a second embodiment of a suction pipe of a centrifugal compressor of the present application;

[0034] Figure 4B is a rear perspective view of a second embodiment of a suction pipe of a centrifugal compressor of the present application;

[0035] Figure 4C is a front view of the inner contour of a second embodiment of a suction pipe of a centrifugal compressor of the present application;

[0036] Figure 4D 1 is a left side view of the inner contour of the second embodiment of the suction pipe of the centrifugal compressor of the present application;

[0037] Figure 4E yes Figure 4D A schematic diagram of a first cross section in FIG;

[0038] Figure 4F yes Figure 4D A schematic diagram of a second cross section in FIG;

[0039] Figure 4G yes Figure 4D A schematic diagram of a third cross section in FIG.

[0040] Figure 4H yes Figure 4D A schematic diagram of a fourth cross section in FIG;

[0041] Figure 4I yes Figure 4D a schematic diagram of a fifth cross section in FIG;

[0042] Figure 4J yes Figure 4A Schematic diagram of the inner contour of the downstream interface of the suction pipe of a centrifugal compressor is shown. DETAILED DESCRIPTION

[0043] Various embodiments of the present application will be described hereinafter with reference to the accompanying drawings, which are incorporated in the specification by way of reference, wherein like numerals refer to like elements throughout. It should be noted that, as used in this specification, the expression "exemplary" is intended to mean that exemplary implementations are mere examples or illustrations.

[0044] The present application provides an improved suction pipe of a centrifugal compressor, which reduces pressure loss of fluid in the suction pipe by changing the shape of the suction pipe.

[0045] Figure 1A and 1B The overall structure of a water chiller 100 using the suction pipe of the centrifugal compressor of the present application is shown, wherein Figure 1A is a perspective view of the water chiller 100, Figure 1B is a simplified left side view of the water chiller 100. As Figure 1A and 1B shown, the water chiller 100 includes an evaporator 110, a centrifugal compressor 120, a condenser 130 and a throttling device (not shown in the figure) forming a refrigeration cycle. The centrifugal compressor 120 has a suction port 125 having a central axis X1. The evaporator 110 includes a substantially cylindrical cylinder having an axis X2 parallel to the central axis X1 of the suction port 125 of the centrifugal compressor 120 and a diameter D0. The water chiller 100 further includes a suction pipe 150 connecting the evaporator 110 and the centrifugal compressor 120. The evaporator 110 is an upstream component of the centrifugal compressor 120.

[0046] The refrigeration cycle of the chiller 100 includes four processes: compression, condensation, throttling, and evaporation. During the compression process, the refrigerant gas exiting the evaporator 110 first attains high speed through the high-speed rotation of the impeller of the centrifugal compressor 120. It then undergoes expansion and deceleration through the diffuser and volute, becoming a high-temperature, high-pressure refrigerant gas. During the condensation process, the high-temperature, high-pressure refrigerant gas exiting the centrifugal compressor 120 enters the condenser 130 for condensation. The high-temperature, high-pressure refrigerant exchanges heat with the relatively low-temperature cooling water flowing through the condenser 130, condensing into a liquid state. During the throttling process, the high-pressure, room-temperature refrigerant liquid exiting the condenser 130 passes through a throttling device (e.g., a throttling orifice plate) and becomes a low-temperature, low-pressure refrigerant liquid. During the evaporation process, the low-temperature, low-pressure refrigerant liquid exiting the throttling device enters the evaporator 110 and exchanges heat with the cooling water within the evaporator 110, causing the low-temperature, low-pressure refrigerant liquid to evaporate into a refrigerant gas at room temperature and pressure. Intake pipe 150 directs the refrigerant gas from evaporator 110 into centrifugal compressor 120. During this process, because the axes of evaporator 110 and centrifugal compressor 120 are parallel, the flow direction of the refrigerant gas needs to be changed by intake pipe 150. Therefore, intake pipe 150 is generally curved. More specifically, the refrigerant gas from evaporator 110 generally enters intake pipe 150 in a direction approximately perpendicular to the axis of compressor 120, while the refrigerant gas from intake pipe 150 needs to enter the compressor along the axis of compressor 120. Therefore, intake pipe 150 deflects the flow direction of the airflow by approximately 90°.

[0047] Figures 2A-2J FIG. 1 shows a suction pipe 150 of a centrifugal compressor according to a first embodiment of the present application, wherein: Figure 2A is a front perspective view of the intake pipe 150, Figure 2B is a rear perspective view of the intake pipe 150, Figure 2C is a front view of the inner contour of the intake pipe 150, Figure 2D is a left side view of the inner contour of the intake pipe 150, Figures 2E-2I yes Figure 2D Schematic diagram of the first to fifth cross sections in FIG. Figure 2J Schematic diagram of the inner contour of the downstream interface of the suction pipe 150. Figures 2A-2C As shown, the suction pipe 150 has an imaginary middle section 250, which is coplanar with the axis of the centrifugal compressor, that is, the axis of the centrifugal compressor is located on the middle section 250. The suction pipe 150 is a tubular structure that is bilaterally symmetrical with respect to the middle section 250.

[0048] Still like Figures 2A-2CAs shown, the suction pipe 150 generally comprises three sections connected in sequence, an inlet section 211, a transition section 212 and an outlet section 213. The inlet section 211 connects the suction pipe 150 with the evaporator 110, the outlet section 213 connects the suction pipe 150 with the compressor 120, and the transition section 212 connects the inlet section 211 and the outlet section 213. The refrigerant gas coming out of the evaporator 110 enters the inlet section 211 in a direction generally perpendicular to the central axis X1 of the suction port 125 of the compressor 120, and enters the compressor 120 from the outlet section 213 in a direction generally along the central axis X1 of the suction port 125 of the compressor 120, so the flow direction of the refrigerant gas in the suction pipe 150 is generally deflected by 90°. Among them, although the flow direction of the refrigerant gas also deflects a little in the inlet section 211 and the outlet section 213, the deflection of the flow direction mainly occurs in the transition section 212. The end surface of the outlet section 213 connected with the suction port 125 of the compressor 120 is a downstream interface 226, which is generally a circular ring shape, matching the shape of the suction port 125 of the compressor 120. Therefore, the inner contour of the downstream interface 226 is circular. The end surface of the inlet section 211 connected with the evaporator 110 is an upstream interface 228.

[0049] The inlet section 211 comprises a connecting portion 241 and a guiding portion 242 connected with each other, the guiding portion 242 is located downstream of the connecting portion 241, and the connecting portion 241 is used to realize the mechanical connection between the suction pipe 150 and the evaporator 110. The upstream interface 228 is formed by the connecting portion 241, which forms the starting position of the fluid guiding channel. From the upstream interface 228, the refrigerant gas enters the guiding portion 242, and then enters the transition section 212. Figures 2A-2D It can be seen that the upstream portion of the inlet section 211 (including the connecting portion 241 and part of the guiding portion 242) is in the form of lugs on opposite sides of the middle cross section 250, so as to match the top of the cylindrical evaporator 110. Therefore, the upstream interface 228 has a wave shape.

[0050] Specifically, the inner contour of the upstream interface 228 comprises an upstream inner end point 231, an upstream outer end point 232, an upstream left end point 233 and an upstream right end point 234. Among them, the upstream inner end point 231 and the upstream outer end point 232 are located on the middle cross section 250, and the upstream left end point 233 and the upstream right end point 234 are located on opposite sides of the middle cross section 250. In the direction perpendicular to the axis X2 of the evaporator 110, the upstream inner end point 231 and the upstream outer end point 232 are located above the upstream left end point 233 and the upstream right end point 234. The upstream inner end point 231 and the upstream outer end point 232 will contact the top end of the cylindrical evaporator 110, and the upstream left end point 233 and the upstream right end point 234 will contact the opposite sides of the top end of the cylindrical evaporator 110.

[0051] On the inner profile of the suction pipe 150, the connecting line of the guide portion 242 and the connecting portion 241 is in parallel with the upstream interface 228. The connecting line of the guide portion 242 and the connecting portion 241 intersects with the middle cross section 250 at an inner intersection point 245 and an outer intersection point 246.

[0052] The distance between the upstream inner end point 231 and the upstream outer end point 232 is D1, and the distance between the upstream left end point 233 and the upstream right end point 234 is D2. The distance D1 between the upstream inner end point 231 and the upstream outer end point 232 is the first direction maximum span size of the inner profile of the upstream interface 228 on the middle cross section 250, and is also the maximum span size of the inner profile of the upstream interface 228 in the direction along the axis X2 of the evaporator 110. The distance D2 between the upstream left end point 233 and the upstream right end point 234 is the second maximum span size of the inner profile of the upstream interface 228 in the direction perpendicular to the middle cross section 250, and is also the maximum span size of the inner profile of the upstream interface 228 in the direction perpendicular to the axis X2 of the evaporator 110. The area of the upstream interface 228 determines the local loss ΔP1 of the pressure of the refrigerant gas when entering the suction pipe 150 from the evaporator 110.

[0053] Specifically, when the fluid enters the suction pipe 150 from the evaporator 110, due to the shrinkage mutation of the fluid flow area from large to small at the fluid interface between the cylinder of the evaporator 110 and the suction pipe 150, there is a loss of fluid pressure, i.e. a local loss ΔP1, at the interface between the suction pipe 150 and the evaporator 110, and the size of the projection area A1 of the interface (i.e. the upstream interface 228) between the suction pipe 150 and the evaporator 110 in the projection plane 265 perpendicular to the middle cross section 250 and parallel to the central axis X1 of the suction port 125 of the centrifugal compressor 120 directly determines the size of the local loss ΔP1. More specifically, the local loss ΔP1 of the suction pipe is: where A1 is the projection area of the interface (i.e. the upstream interface 228) between the suction pipe 150 and the evaporator 110 in the projection plane 265, A0 is the axial cross-sectional area of the evaporator 110, V1 is the average flow velocity in the suction pipe 150, and g is the acceleration of gravity.

[0054] In order to reduce the local loss ΔP1, the area A1 of the interface (i.e. the upstream interface 228) between the suction pipe 150 and the evaporator 110 should be as large as possible, but due to the limitation of the diameter of the evaporator cylinder, the distance D2 between the upstream left end point 233 and the upstream right end point 234 (i.e. the maximum span size of the upstream interface 228 in the direction perpendicular to the axis of the evaporator 110) must satisfy D2 < 0.5 × D1 in order to meet the strength requirements of the cylinder of the evaporator 110.

[0055] To this end, according to the suction pipe of the present application, the upstream interface 228 is configured such that a distance D1 (i.e., a first direction maximum span size of the inner contour of the upstream interface 228 on the mid-section 250) between the upstream inner side end point 231 and the upstream outer side end point 232 is greater than a distance D2 (i.e., a second direction maximum span size of the inner contour of the upstream interface 228 in a direction perpendicular to the mid-section 250) between the upstream left side end point 233 and the upstream right side end point 234. Therefore, on the projection plane 265, the projection of the inner contour of the upstream interface 228 is an ellipse, and the projected area A1 is A1 = pi x D1 x D2, where pi is the circular constant.

[0056] By the above configuration of the upstream interface 228, the present application can reduce the local loss ΔP1 to the maximum extent while meeting the strength requirement of the cylinder of the evaporator 110, because increasing the maximum span size D1 of the upstream interface 228 in the direction along the axis X2 of the evaporator 110 can increase the area A1 of the upstream interface 228, thereby effectively reducing the local loss ΔP1.

[0057] According to some embodiments of the present application, the distance (first direction maximum span size) D1 between the upstream inner side end point 231 and the upstream outer side end point 232 and the distance (second direction maximum span size) D2 between the upstream left side end point 233 and the upstream right side end point 234 satisfy: 0.55 < D1 / D0 < 0.7, D2 < 0.5 x D1. And the radius R6 of the inner contour of the downstream interface 226 satisfies: 0.43 < R6 / D1 < 0.57.

[0058] Since the projection of the inner contour of the upstream interface 228 on the projection plane 265 is an ellipse, and the inner contour of the downstream interface 226 is a circle, the cross-section of the suction pipe 150 gradually changes from an ellipse to a circle between the upstream interface 228 and the downstream interface 226.

[0059] The suction pipe 150 has a center line 270 on the mid-section 250, and the center of the cross-section of the suction pipe 150 is on the center line 270. The center line 270 is a spline curve satisfying the following formula: wherein V1, V2, V3, V4 satisfy the following relationships:

[0060] -7e7 < V1 < -6e7, 1100 < V2 < 1300, -2950 < V3 < -2750, 250 < V4 < 270.

[0061] Wherein, the coordinate system involved in the above formula takes the bottom end of the center line 270 (i.e. the intersection point of the center line 270 and the projection plane 265) O0 as the coordinate system origin, takes the direction parallel to the central axis X1 of the suction port 125 of the centrifugal compressor 120 as the X-axis direction, and takes the direction perpendicular to the central axis X1 of the suction port 125 of the centrifugal compressor 120 as the Y-axis direction, as shown in Figure 2D .

[0062] As shown in Figure 2D , the suction pipe 150 has a first cross section 251 passing through the inner intersection point 245 and the outer intersection point 246 and being perpendicular to the mid-section 250, with the center O1 located on the center line 270. That is, the first cross section 251 is parallel to the projection plane 265. Between the first cross section 251 of the suction pipe 150 and the downstream interface 226, the cross section of the inner contour of the suction pipe 150 at least on the inlet section 211 and the transition section 212 is an ellipse with the long axis located on the mid-section 250, and the cross section of the inner contour of the inlet section 211 and the outlet section 213 gradually decreases in the direction towards the downstream interface 226, while the cross section of the inner contour of the transition section 212 gradually increases and then gradually decreases in the direction towards the downstream interface 226. That is, the suction pipe 150 forms a shape similar to a bulge on the transition section 212.

[0063] As an example, the above-mentioned suction pipe 150 is described by the size of a plurality of discrete cross sections. As shown in Figure 2D , the portion of the suction pipe 150 between the first cross section 251 and the downstream interface 226 is equally divided into five parts along the center line 270 into four cross sections, i.e. the second cross section 252, the third cross section 253, the fourth cross section 254 and the fifth cross section 255, and the centers of these cross sections are on the center line 270, i.e. O2, O3, O4 and O5. Among them, the fourth cross section 254 is the largest cross section of the transition section 212. The size characteristics of the first cross section 251 and the downstream interface 226, as well as the above cross sections are as follows.

[0064] The included angle a6 between the downstream interface 226 and the first cross section 251 and the radius R6 of the downstream interface 226 satisfy:

[0065] 80°≤a6≤90°, 0.43<R6 / D1<0.57.

[0066] The long axis radius R1max and the short axis radius R1min of the first cross section 251 respectively satisfy: 1max =0.5×D1, 0.9<R 1min / R 1max <0.95.

[0067] the angle a2 of the second cross section 252 with the first cross section 251 and the major axis radius R of the second cross section 252 2max and the minor axis radius R 2min respectively satisfy: 0.1 < a2 / a6 < 0.15, 0.68 < R 2max / D1 < 0.78, 0.92 < R 2min / R 2max < 0.98.

[0068] the angle a3 of the third cross section 253 with the first cross section 251 and the major axis radius R of the third cross section 253 3max and the minor axis radius R 3min respectively satisfy: 0.25 < a3 / a6 < 0.38, 0.6 < R 3max / D1 < 0.76, 0.8 < R 3min / R 3max < 0.9.

[0069] the angle a4 of the fourth cross section 254 with the first cross section 251 and the major axis radius R of the fourth cross section 254 4max and the minor axis radius R 4min respectively satisfy: 0.45 < a4 / a6 < 0.6, 0.6 < R 4max / D1 < 0.74, 0.84 < R 4min / R 4max < 0.92.

[0070] the angle a5 of the fifth cross section 255 with the first cross section 251 and the major axis radius R of the fifth cross section 255 5max and the minor axis radius R 5min respectively satisfy: 0.7 < a5 / a6 < 0.8, 0.45 < R 5max / D1 < 0.6, 0.98 < R 5min / R 5max < 1.05.

[0071] It can be seen that the first to fourth cross sections are all elliptical with the major axis on the middle cross section 250, while the fifth cross section 255 can have a minor axis larger than, equal to, or shorter than the major axis, thus the fifth cross section 255 can be circular.

[0072] By forming the above cross sections, the upstream interface 228, the downstream interface 226 and the center line 270, the inner contour of the suction pipe 150 can be formed, and then by adding a wall with a certain thickness, the suction pipe 150 can be formed.

[0073] Figure 3A is a schematic diagram showing the fluid flow state of a comparative example suction pipe 310 in use, Figure 3Bis a schematic view showing the fluid flow state of the suction pipe 150 according to the first embodiment of the present application in use. As shown in Figure 3A In one comparative example, the suction pipe 310 is a circular pipe as a whole, and the inlet section 311 of the suction pipe 310 is a straight pipe section perpendicular to the evaporator 320. Due to the abrupt change of the interface area between the evaporator 320 and the suction pipe 310, there is a local pressure loss ΔPl of the refrigerant gas when it enters the suction pipe 310 from the evaporator 320. Moreover, there is a pressure loss ΔP2 of the refrigerant gas in the straight pipe-shaped inlet section 311, because when the fluid enters the suction pipe 310 from the evaporator 320, the flow direction is deflected greatly, and the fluid will separate and swirl when the flow direction is deflected greatly. In addition, there is a pressure loss ΔP3 of the refrigerant gas in the transition section 312 of the suction pipe 310, because the fluid is deflected greatly in the transition section 312, and the deflection of the fluid flow causes the velocity distribution to be uneven in the transition section 312 of the suction pipe, which results in the increase of the internal friction in the main flow, and the increase of the turbulence in the main flow due to the forward and backward impacts of the fluid clusters, thus causing the loss of pressure and energy. There is also a pressure loss ΔP4 of the refrigerant gas in the outlet section 313 of the suction pipe 310, because there is a local high-speed area near the inner side of the suction pipe, which increases the internal friction of the fluid, thus causing the pressure loss.

[0074] While the comparative example shown in Figure 3B The suction pipe 150 according to the first embodiment of the present application can greatly reduce the pressure losses ΔPl, ΔP2, ΔP3 and ΔP4 in the above comparative example. The reason for reducing the local pressure loss ΔPl has been described in detail above, and will not be repeated here. The suction pipe 150 of the present application can also reduce the pressure loss ΔP2 of the inlet section, because the cross section of the inlet section 211 of the suction pipe 150 of the present application is gradually reduced, thus reducing the deflection of the flow direction when the fluid enters the suction pipe 310 from the evaporator 320. The suction pipe 150 of the present application can also reduce the pressure loss ΔP3 of the transition section, because the cross section of the transition section 212 is first increased and then reduced, which can reduce the uneven velocity distribution caused by the deflection of the flow direction. The suction pipe 150 of the present application can also reduce the pressure loss ΔP4 of the outlet section, because the process of the cross section of the transition section 212 being first increased and then reduced reduces the flow velocity of the local high-speed area near the inner side of the outlet section 313 of the suction pipe.

[0075] Figure 3C and 3D respectively show the velocity vector diagrams in the suction pipe 310 of the comparative example shown in Figure 3A and the suction pipe 150 of the present application shown in Figure 3B From the CFD simulation results, it can be seen that, Figure 3AThe suction pipe 310 of the comparative example shown has two turbulent vortex areas (the darker areas in the figure) on the left and right sides of the bottom of the suction pipe, while Figure 3B The turbulent vortex is basically eliminated on both sides of the bottom of the suction pipe 150 of the present application, which can effectively reduce the pressure loss. As shown in Table 1 below, Figure 3B The pressure loss ratio of the intake pipe 150 of the present application is shown as Figure 3A The air intake pipe 310 of the comparative example shown is reduced by 17%.

[0076] Figure 3E and 3F Shown are the Figure 3A The air intake pipe 310 of the comparative example shown and Figure 3B The velocity vector diagram at the downstream interface of the intake pipe (i.e., the compressor inlet) of the intake pipe 150 of the present application is obtained using the CFD (computational fluid dynamics) method; Figure 3G and 3H Shown are the Figure 3A The air intake pipe 310 of the comparative example shown and Figure 3B The vortex intensity diagram of the intake pipe downstream interface (i.e., compressor inlet) of the intake pipe 150 of the present application is obtained by using the CFD (computational fluid dynamics) method. The velocity distribution at the downstream interface of the intake pipe (i.e., compressor inlet) has a great influence on the performance of the compressor. The more uniform the velocity distribution at the compressor inlet, the higher the efficiency of the compressor. The influence of the intake pipe on the performance of the compressor can be judged by the vortex intensity at the interface end face between the intake pipe and the compressor. Generally speaking, the smaller the vortex intensity, the better the efficiency of the compressor. Figures 3E-3H As can be seen, the velocity distribution at the downstream interface of the intake pipe 150 of the present application (i.e., at the compressor inlet) is more uniform, and the vortex intensity is significantly reduced (darker colors represent higher flow rates and greater vortex intensity). Furthermore, as can be seen from Table 1, the vortex intensity of the intake pipe 150 of the present application is 74% lower than that of existing intake pipes, significantly improving the compressor inlet conditions and enhancing compressor performance.

[0077] Figures 4A-4D FIG. 4 shows a suction pipe 450 of a centrifugal compressor according to a second embodiment of the present application, wherein: Figure 4A is a front perspective view of the intake pipe 450, Figure 4B is a rear perspective view of the intake pipe 450, Figure 4C is a front view of the inner contour of the intake pipe 450, Figure 4D It is a left view of the inner contour of the intake pipe 450. Figures 4E-4I yes Figure 4D Schematic diagram of the first to fifth cross sections in FIG. Figure 4J Schematic diagram of the inner contour of the downstream interface of the suction pipe 450. Figures 4A-4JThe air intake pipe 450 of the second embodiment shown is Figures 2A-2J The main difference between the intake duct 150 of the first embodiment shown is that the cross section of the inner contour of the transition section 612 of the intake duct 150 of the first embodiment first gradually increases and then gradually decreases, while the cross section of the inner contour of the transition section 612 of the intake duct 450 of the second embodiment does not have an increasing portion, but gradually decreases in the direction toward the downstream interface 626. In other words, the cross section of the inner contour of the intake duct 450 of the second embodiment increases from the first cross section 651 (with its center at O 11 ) gradually decreases in the direction from the downstream interface 626. As shown in Table 1 below, the intake duct 450 of the second embodiment, like the intake duct 150 of the first embodiment, can reduce the static pressure loss in the pressure loss intake duct and the vortex intensity at the downstream interface of the intake duct.

[0078] As in the first embodiment, the distance D between the upstream inner end point 631 and the upstream outer end point 632 of the air intake pipe 450 of the second embodiment (maximum span in the first direction) is 11 The distance between the upstream left end point 633 and the upstream right end point 634 (the maximum span in the second direction) D 12 Satisfied: 0.55 <D 11 / D0<0.7,D 12 <0.5×D 11 The radius R of the inner contour of the downstream interface 626 is 16 Satisfied: 0.43 <R 16 / D 11 <0.57. Where D0 is the diameter of the upstream evaporator.

[0079] As an example, the above-mentioned air intake duct 450 is described by a plurality of discrete cross-sectional dimensions. Figure 2D As shown, the portion of the suction pipe 450 between the first cross section 651 and the downstream interface 626 is divided into five equal cross sections along the center line 670. The four cross sections are respectively a second cross section 652, a third cross section 653, a fourth cross section 654 and a fifth cross section 655. The centers of these cross sections are all on the center line 670, and are respectively O 12 , O 13 , O 14 and O 15 The fourth cross section 654 is the largest cross section of the transition section 612. The first cross section 651 and the downstream interface 626, as well as the dimensions of the above cross sections, are as follows.

[0080] Angle α between the downstream interface 626 and the first cross section 651 16 and the radius R of the downstream interface 626 16 satisfy:

[0081] 80°≤α 16 ≤90°, 0.43 < R 16 / D 11 <0.57.

[0082] The long axis radius R 11max and the short axis radius R 12min of the first cross section 651 satisfy: 0.5 < R 11max / D 11 , 0.9 < R 11min / R 11max <0.95.

[0083] The angle a 12 between the second cross section 652 and the first cross section 651, and the long axis radius R 12max and the short axis radius R 12min of the second cross section 652 satisfy: 0.1 < a 12 / a 16 <0.15, 0.68 < R 12max / D 11 <0.78, 0.92 < R 12min / R 12max <0.98.

[0084] The angle a 13 between the third cross section 653 and the first cross section 651, and the long axis radius R 13max and the short axis radius R 13min of the third cross section 653 satisfy: 0.25 < a 13 / a 16 <0.38, 0.55 < R 13max / D 11 <0.7, 0.8 < R 13min / R 13max <0.9.

[0085] The angle a 14 between the fourth cross section 654 and the first cross section 651, and the long axis radius R 14max and the short axis radius R 14min of the fourth cross section 654 satisfy: 0.45 < a 14 / a 16 <0.6, 0.5 < R 14max / D 11 <0.6, 0.9 < R 14min / R 14max <0.95.

[0086] The angle a 15 between the fifth cross section 655 and the first cross section 651, and the long axis radius R 15max and the short axis radius R15min respectively: 0.7 < a 15 / a 16 <0.8, 0.45 < R 15max / D 11 <0.6, 0.98 < R 15min / R 15max <1.05.

[0087] The following Table 1 shows a performance comparison table of the suction pipe of two embodiments of the present application and the suction pipe of a comparative example in terms of static pressure loss and vortex intensity.

[0088] Table 1 Suction pipe performance comparison

[0089] Suction pipe Static pressure loss (Pa) Vortex strength (s"1) Suction pipe 310 of the comparative example 2578 13.9 Suction pipe 150 of the first embodiment of the present application 2145 3.8 Suction pipe 450 of the second embodiment of the present application 2205 4.5

[0090] While the present disclosure has been described and illustrated with respect to examples of the embodiments outlined above, various alternatives, modifications, changes, improvements, and / or substantial equivalents can be apparent to those of ordinary skill in the art. In addition, the technical effects and / or technical problems described in this specification are exemplary and / or are not necessarily the only technical effects and / or technical problems solved by the disclosure. Accordingly, the examples of the embodiments of the present disclosure as set forth above are intended to be illustrative not limiting. Various changes can be made without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to include all alternatives, modifications, changes, improvements, and / or substantial equivalents.

Claims

1. A suction duct of a centrifugal compressor, the centrifugal compressor having a suction port with a central axis, the suction duct conducting fluid from an upstream component into the centrifugal compressor, the fluid entering the suction duct in a direction substantially perpendicular to the central axis of the suction port, the suction duct comprising: - an imaginary mid-section on which the central axis of the suction port of the centrifugal compressor lies, the suction duct having a shape symmetrical with respect to the mid-section; - a downstream interface to connect with the centrifugal compressor, the inner profile of the downstream interface being circular and connected with the suction port; and - an upstream interface to connect with the upstream component; characterized in that the inner profile of the upstream interface comprises a first direction maximum cross dimension D1 on the mid-section and a second direction maximum cross dimension D2 perpendicular to the mid-section, wherein the first direction maximum cross dimension D1 is greater than the second direction maximum cross dimension D2; wherein the upstream component is a cylindrical having a diameter D0 parallel to the central axis of the suction port; wherein the first direction maximum cross dimension D1 and the second direction maximum cross dimension D2 of the inner profile of the upstream interface satisfy: 0.55 < D1 / D0 < 0.7, D2 < 0.5 x D1. And wherein the radius R6 of the inner profile of the downstream interface satisfies: 0.43 < R6 < 0.

57. 6max / D1 < 0.

57.

2. The suction duct of a centrifugal compressor according to claim 1, characterized in that: - the suction duct has a center line on the mid-section; The center line is a spline curve, and the center line satisfies the following formula: V1, V2, V3, and V4 satisfy the following relationship: - 7e7 < V1 < -6e7, 1100 < V2 < 1300, -2950 < V3 < -2750, 250 < V4 < 270.

3. The suction pipe of the centrifugal compressor according to claim 2, characterized in that: - the suction duct comprises: - an inlet section, the upstream interface being an end face of the inlet section, the inlet section comprising a connection portion to connect the suction duct with the upstream component and a guide portion, the inner profile of the guide portion and the connection line of the inner profile of the connection portion intersecting the mid-section at an inner intersection point and an outer intersection point; - an outlet section, the downstream interface being an end face of the outlet section; - a transition section to connect the inlet section with the outlet section; wherein the suction duct comprises a first cross-section, the first cross-section passing through the inner and outer intersection points and being perpendicular to the mid-section; and wherein, between the first cross-section and the downstream interface, the inner profile of the suction duct at least on the inlet section and the transition section is an ellipse with a major axis on the mid-section.

4. The suction duct of a centrifugal compressor according to claim 3, characterized in that: wherein, - between the first cross-section and the downstream interface, the inner profile of the inlet section and the outlet section of the suction duct gradually decreases in a direction towards the downstream interface.

5. The suction duct of a centrifugal compressor according to claim 4, characterized in that: - the inner profile of the suction duct at the transition section gradually increases and then gradually decreases in a direction towards the downstream interface.

6. The suction duct of a centrifugal compressor according to claim 5, characterized in that: Four cross sections equally dividing the portion of the suction pipe between the first cross section and the downstream interface along the center line into five parts are a second cross section, a third cross section, a fourth cross section and a fifth cross section, wherein the fourth cross section is the largest cross section of the transition section; wherein an angle a6 between the downstream interface and the first cross section satisfies: 80°≤α6≤90°； wherein the long axis radius R 1max and the short axis radius R 1min of the first cross section respectively satisfy: R 1max = 0.5 x D1, 0.9 < R 1min / R 1max < 0.95; wherein the angle a2 of the second cross section with the first cross section and the long axis radius R 2max and the short axis radius R 2min respectively satisfy: 0.1 < a2 / a6 < 0.15, 0.68 < R 2max / D1 < 0.78, 0.92 < R 2min / R 2max < 0.98; wherein the angle a3 of the third cross section with the first cross section and the long axis radius R 3max and the short axis radius R 3min respectively satisfy: 0.25 < a3 / a6 < 0.38, 0.6 < R 3max / D1 < 0.76, 0.8 < R 3min / R 3max < 0.9; wherein the angle a4 of the fourth cross section with the first cross section and the long axis radius R 4max and the short axis radius R 4min respectively satisfy: 0.45 < α4 / α6 < 0.6, 0.6 < R 4max / D1 < 0.74, 0.84 < R 4min / R 4max < 0.92; wherein the angle a5 of the fifth cross section with the first cross section and the major radius R 5max and the minor radius R 5min respectively satisfy: 0.7 < α5 / α6 < 0.8, 0.45 < R 5max / D1 < 0.6, 0.98 < R 5min / R 5max < 1.

05.

7. The suction pipe of the centrifugal compressor according to claim 4, characterized in that: The cross section of the suction pipe at the transition section gradually decreases in the direction towards the downstream interface.

8. The suction pipe of the centrifugal compressor according to claim 7, characterized in that: Four cross sections equally dividing the portion of the suction pipe between the first cross section and the downstream interface along the center line into five parts are a second cross section, a third cross section, a fourth cross section and a fifth cross section, wherein the fourth cross section is the largest cross section of the transition section; Wherein, the angle a between the downstream interface and the first cross section 16 Satisfies: 80°≤α 16 ≤90°； wherein the long axis radius R 11min and the short axis radius R 12min of the first cross section respectively satisfy: R 11max = 0.5 x D 11 , 0.9 < R 11min / R 11max < 0.95; wherein the angle a between the second cross section and the first cross section 12 and the long axis radius R 12max and the short axis radius R 12min of the second cross section respectively satisfy: 0.1 < α 12 / α 16 <0.15, 0.68 < R 12max / D 11 <0.78, 0.92 < R 12min / R 12max <0.98; wherein the third cross section has an angle a with the first cross section 13 and the long axis radius R 13max and the short axis radius R 13min of the third cross section, respectively, satisfy: 0.25 < a 13 / a 16 <0.38, 0.55 < R 13max / D 11 <0.7, 0.8 < R 13min / R 13max <0.9; wherein the fourth cross section has an angle a with the first cross section 14 and the long axis radius R 14max and the short axis radius R 14min respectively satisfy: 0.45 < a 14 / a 16 <0.6, 0.5 < R 14max / D 11 <0.6, 0.9 < R 14min / R 14max <0.95; wherein the fifth cross section has an angle a with the first cross section 15 and the major axis radius R 15max and the minor axis radius R 15min of the fifth cross section, respectively, satisfy: 0.7 < α 15 / α 16 <0.8, 0.45 < R 15max / D 11 <0.6, 0.98 < R 15min / R 15max <1.

05.

9. A centrifugal compressor characterized by: The centrifugal compressor comprises the suction pipe according to any one of claims 1-8.

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