Low-flow efficient oil-air cooler for transformer

Abstract

The invention discloses a low-flow transformer efficient oil-air cooler which comprises a cooler body, an air guide cover is installed on one side of the cooler body, a fan is installed in the air guide cover, an oil inlet pipe and an oil outlet pipe are arranged on the cooler body, a butterfly valve is connected to the oil outlet pipe, an oil pump is connected to the butterfly valve, and an outlet of the oil pump is connected with a connecting pipe. A finned tube is arranged between the oil inlet tube and the oil outlet tube; the finned tube comprises an inner tube and an outer tube, and fins are arranged on the outer tube; a lining pipe is arranged between the inner pipe and the outer pipe, and the outer surface of the lining pipe abuts against the outer pipe and the inner pipe at the same time to form a limiting structure. According to the low-flow efficient oil-air cooler for the transformer, a specific structure is adopted, and oil flowing channels in the finned tubes are increased, so that the heat transfer area in the finned tubes is increased, the heat exchange efficiency is improved, the oil flowing speed is reduced, oil flow electrification can be avoided, and the operation safety of the transformer is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of transformer cooler technology, and more specifically to a low-flow-rate, high-efficiency oil-air cooler for transformers. Background Technology

[0002] As one of the most critical electrical devices in a power system, the safe operation of a transformer directly impacts the safety and stability of the power grid. During transformer operation, losses in the windings and core generate a significant amount of heat, which must be dissipated promptly to prevent overheating and insulation damage. Therefore, coolers are essential auxiliary facilities for transformer operation. Coolers are a type of heat exchange equipment used to cool fluids, typically using water or air as the coolant to remove heat; they can be mainly classified into tubular coolers, plate coolers, and air-cooled coolers. Among these, oil-air coolers are widely used in large transformers, maintaining the normal operating oil temperature and ensuring the transformer's normal operation.

[0003] Finned tubes are heat transfer elements that improve heat exchange efficiency by increasing the fin area. Finned tube oil-air coolers are devices that achieve cooling through heat exchange between air and the surface of the tube. Their core component is the finned tube, which significantly increases the heat dissipation area and improves heat exchange efficiency. However, in existing finned tube oil-air coolers, the internal space of the finned tube is a single cylindrical structure, resulting in relatively low heat transfer efficiency. The large flow rate of oil passing through can cause the oil to become electrified, affecting the safe operation of the transformer. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a low-flow-rate high-efficiency oil-air cooler for transformers. This low-flow-rate high-efficiency oil-air cooler for transformers, through a specific structure, increases the oil flow channels inside the finned tubes, thereby increasing the heat transfer area inside the finned tubes, improving heat exchange efficiency, and reducing the oil flow velocity. This prevents the oil from becoming electrified, effectively improving the safety of transformer operation.

[0005] The technical solution of this application is as follows:

[0006] A low-flow transformer high-efficiency oil-air cooler includes a cooler body, an air guide shroud installed on one side of the cooler body, a fan installed inside the air guide shroud, an oil inlet pipe and an oil outlet pipe on the cooler body, a butterfly valve connected to the oil outlet pipe, an oil pump connected to the butterfly valve, and a connecting pipe connected to the outlet of the oil pump; a set of finned tubes is provided between the oil inlet pipe and the oil outlet pipe for heat exchange of the oil; the upper end of the finned tube is connected to the oil inlet pipe through a branch pipe, and the lower end of the finned tube is connected to the oil outlet pipe through a manifold pipe; the finned tube includes an inner tube and an outer tube, and fins are provided on the outer wall of the outer tube in a spiral arrangement; a set of liner tubes evenly distributed circumferentially are provided between the inner tube and the outer tube, and the outer surface of the liner tubes abuts against both the outer tube and the inner tube to form a limiting structure.

[0007] Compared with the prior art, the low-flow transformer high-efficiency oil-air cooler of this application has a set of finned tubes between the oil inlet pipe and the oil outlet pipe, and a set of uniformly distributed liner tubes between the inner and outer tubes of the finned tubes to increase the oil flow channel inside the finned tubes. This increases the heat dissipation area inside the finned tubes, improves the heat exchange efficiency, and reduces the oil flow velocity, thereby preventing the oil from becoming electrified and effectively improving the safety of transformer operation. At the same time, it can reduce the energy consumption of the oil pump.

[0008] As an optimization, in the aforementioned low-flow transformer high-efficiency oil-air cooler, the liner has a cylindrical structure. The cross-section of the liner consists of a bottom edge, a top edge, and two side edges connecting the bottom and top edges. The bottom edge abuts against the inner tube, and the top edge abuts against the outer tube. Both the bottom and top edges are arc-shaped. The radius of curvature of the bottom edge is equal to the radius of curvature of the outer wall of the inner tube, and the radius of curvature of the top edge is equal to the radius of curvature of the inner wall of the outer tube. This specific structure allows for better fit between the inner and outer tubes, resulting in a more compact overall structure. Furthermore, the liner's fit with the inner and outer tubes via arc surfaces of the same curvature creates a reliable limiting structure with a long service life.

[0009] Furthermore, in the aforementioned low-flow transformer high-efficiency oil-air cooler, both the bottom and top edges are connected to the side edges via rounded corner structures. This structure facilitates manufacturing, avoids stress concentration, and improves structural strength.

[0010] As an optimization, in the aforementioned low-flow transformer high-efficiency oil-air cooler, the top side is longer than the bottom side, forming a structure that is larger on the outside and smaller on the inside. This allows for the arrangement of a larger number of liner tubes, which is beneficial for achieving better structural stability and higher heat transfer efficiency.

[0011] As an optimization, in the aforementioned low-flow transformer high-efficiency oil-air cooler, the number of liner tubes can be 16-24.

[0012] As an optimization, in the aforementioned low-flow transformer high-efficiency oil-air cooler, the manufacturing process of the finned tube is as follows: ① Fix the outer tube in place; ② Arrange the liner tubes inside the outer tube and limit their position; ③ Place the inner tube at the center inside the outer tube; ④ Expand the inner tube so that the inner tube, liner tube, and outer tube form an integral structure through expansion. Using this manufacturing process, the finned tubes form an integral structure through expansion, resulting in a tight internal connection and good sealing performance; moreover, the expansion process is simple and easy to operate and maintain.

[0013] As an optimization, in the aforementioned low-flow transformer high-efficiency oil-air cooler, the fins are formed by extrusion rolling of the outer tube. This process results in an integral structure between the fins and the outer tube, leading to low thermal resistance and good heat transfer efficiency.

[0014] As an optimization, in the aforementioned low-flow transformer high-efficiency oil-air cooler, the expansion fitting for forming the aforementioned finned tube includes a support, an expansion rod, and a pair of outer tube positioning plates and inner tube positioning plates; the inner tube positioning plate is located outside the outer tube positioning plate and abuts against it; the inner tube positioning plate and the outer tube positioning plate are detachably mounted on the support; the inner tube positioning plate has a positioning hole A, and the outer tube positioning plate has a positioning hole B, the center lines of the positioning holes A and B coincide; the inner tube positioning plate has a set of liner positioning blocks; the expansion rod has a pair of bosses, and when the expansion rod is inserted into the inner tube, the bosses are sealed to the inner wall of the inner tube; one end of the expansion rod... The device includes an inlet hole and an outlet hole on the side of the expansion rod, which are connected to the inlet hole. A limiting plate is detachably connected to the bracket, and the limiting plate abuts against the inner tube positioning plate located at the upper end. The limiting plate has a through hole, and the inner wall of the through hole abuts against the outer wall of the expansion rod. The steps of forming the finned tube using the expansion tooling include: ① placing the outer tube in positioning hole B; ② arranging the liner tubes inside the outer tube and limiting the liner tubes with liner tube positioning blocks; ③ placing the inner tube in positioning hole A; ④ inserting the expansion rod into the inner tube; ⑤ inserting an external high-pressure water supply device into the inlet hole; ⑥ the inner tube expands under water pressure, so that the inner tube, liner tube, and outer tube form an integral structure through expansion. Using this expansion tooling for manufacturing finned tubes is simple and quick, with low manufacturing costs; it is also easy to disassemble and maintain, and easy to promote and use.

[0015] As an optimization, in the aforementioned low-flow transformer high-efficiency oil-air cooler, one end of the expansion rod with a water inlet hole is connected to a water inlet connector. This structure facilitates connection to an external high-pressure water supply device.

[0016] As an optimization, in the aforementioned low-flow transformer high-efficiency oil-air cooler, the boss is provided with a sealing groove, and a sealing ring is fitted onto the sealing groove. This structure can further enhance the sealing effect. Attached Figure Description

[0017] Figure 1 This is a structural schematic diagram of the low-flow transformer high-efficiency oil-air cooler in this application;

[0018] Figure 2 This is a schematic diagram of the structure of the finned tube in this application;

[0019] Figure 3 This is a cross-sectional view of the finned tube in this application;

[0020] Figure 4 This is a schematic diagram of the structure of the expansion joint tooling with finned tubes installed in this application;

[0021] Figure 5 yes Figure 4 A cross-sectional view;

[0022] Figure 6 yes Figure 5 A schematic diagram of a tube without fins;

[0023] Figure 7 This is a schematic diagram of the expansion rod in this application;

[0024] Figure 8 This is a schematic diagram of the structure of the inner tube positioning plate in this application.

[0025] The labels in the attached diagram are as follows: 1-Cooler body, 11-Oil inlet pipe, 12-Oil outlet pipe; 2-Air guide shroud; 3-Fan; 4-Butterfly valve; 5-Oil pump; 6-Connecting pipe; 7-Finned tube, 71-Inner tube, 72-Outer tube, 721-Fin, 73-Liner; 8-Expansion fitting, 81-Bracket, 82-Outer tube positioning plate, 821-B positioning hole, 83-Inner tube positioning plate, 831-A positioning hole, 832-Liner positioning block, 84-Expansion rod, 841-Boss, 842-Water inlet hole, 843-Water outlet hole, 85-Sealing ring, 86-Limiting plate, 861-Through hole, 87-Water inlet connector. Detailed Implementation

[0026] The present application will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present application. In the following embodiments, content not described in detail or shown in detail in the accompanying drawings is common knowledge in the art.

[0027] Example (see) Figures 1 to 8 ):

[0028] A low-flow transformer high-efficiency oil-air cooler includes a cooler body 1, a guide shroud 2 installed on one side of the cooler body 1, a fan 3 installed inside the guide shroud 2, an oil inlet pipe 11 and an oil outlet pipe 12 on the cooler body 1, a butterfly valve 4 connected to the oil outlet pipe 12, an oil pump 5 connected to the butterfly valve 4, and a connecting pipe 6 connected to the outlet of the oil pump 5; a set of finned tubes 7 is provided between the oil inlet pipe 11 and the oil outlet pipe 12 for heat exchange of the oil; The upper end of the finned tube 7 is connected to the oil inlet pipe 11 through a branch pipe, and the lower end of the finned tube 7 is connected to the oil outlet pipe 12 through a manifold pipe. The finned tube 7 includes an inner tube 71 and an outer tube 72. The outer wall of the outer tube 72 is provided with fins 721, which are spirally arranged on the outer tube 72. A set of liner tubes 73 are provided between the inner tube 71 and the outer tube 72, and the outer surface of the liner tubes 73 abuts against both the outer tube 72 and the inner tube 71 to form a limiting structure.

[0029] In this embodiment, the liner 73 has a cylindrical structure. The cross-section of the liner 73 consists of a bottom edge, a top edge, and two side edges connecting the bottom and top edges. The bottom edge abuts against the inner tube 71, and the top edge abuts against the outer tube 72. Both the bottom and top edges are arc-shaped. The radius of curvature of the bottom edge is equal to the radius of curvature of the outer wall of the inner tube, and the radius of curvature of the top edge is equal to the radius of curvature of the inner wall of the outer tube. With this specific structure, when the arc-shaped bottom and top edges contact the inner tube 71 and outer tube 72 respectively, they can better fit the inner tube 71 and outer tube 72, making the overall structure more compact.

[0030] In this embodiment, both the bottom and top edges are connected to the side edges via rounded corner structures. This structure facilitates manufacturing, avoids stress concentration, and improves structural strength.

[0031] In this embodiment, the top edge is longer than the bottom edge, forming a structure that is larger on the outside and smaller on the inside. This allows for the arrangement of a larger number of liner tubes, which is beneficial for achieving better structural stability and higher heat transfer efficiency.

[0032] In this embodiment, there are 20 liner tubes 73. This number of liner tubes 73 results in a simple structure while providing more oil flow channels, thus increasing the contact area between the oil and the flow channels and improving heat transfer efficiency.

[0033] In this embodiment, the fins 721 are formed by extrusion rolling of the outer tube 72. The fins 721 and the outer tube 72 formed by this process are an integral structure with good heat transfer efficiency.

[0034] When the low-flow transformer high-efficiency oil-air cooler of this embodiment is working, hot oil flows in from the oil inlet pipe 11, passes through the finned tube 7, transfers heat to the finned tube 7, and flows out from the oil outlet pipe 12. At this time, a negative pressure zone is formed inside the cooler body 1 under the action of the fan 3, which draws in external air into the cooler. During this process, the external air flows through the finned tube 7 and comes into full contact with the fins 721 on the finned tube 7, thereby realizing heat exchange.

[0035] In this embodiment, the finned tube 7 is formed by expansion fitting 8. Expansion fitting 8 includes a bracket 81, an expansion rod 84, and a pair of outer tube positioning plates 82 and inner tube positioning plates 83. The inner tube positioning plate 83 is located outside the outer tube positioning plate 82 and abuts against it. The inner tube positioning plate 83 and the outer tube positioning plate 82 are detachably mounted on the bracket 81. The inner tube positioning plate 83 has an A positioning hole 831, and the outer tube positioning plate 82 has a B positioning hole 821. The center lines of the A positioning hole 831 and the B positioning hole 821 coincide. The inner tube positioning plate 83 has a set of liner positioning blocks 83. 2; The expansion rod 84 is provided with a pair of bosses 841. When the expansion rod 84 is inserted into the inner tube 71, the bosses 841 are sealed to the inner wall of the inner tube 71; One end of the expansion rod 84 is provided with a water inlet hole 842, and the side of the expansion rod 84 is provided with a water outlet hole 843, which is connected to the water inlet hole 842; A limiting plate 86 is detachably connected to the bracket 81, and the limiting plate 86 abuts against the inner tube positioning plate 83 located at the upper end; The limiting plate 86 is provided with a through hole 861, and the inner wall of the through hole 861 abuts against the outer wall of the expansion rod 84.

[0036] In this embodiment, one end of the expansion rod 84 has a water inlet hole 842, which is connected to the water inlet connector 87. This structure facilitates connection to an external high-pressure water supply device.

[0037] In this embodiment, the boss 841 is provided with a sealing groove, and a sealing ring 85 is fitted onto the sealing groove. This structure can further enhance the sealing effect.

[0038] In this embodiment, the specific expansion process is as follows: ① Place the outer tube 72 in the B positioning hole 821; ② Arrange the liner 73 inside the outer tube 72 and limit the liner 73 by the liner positioning block 832; ③ Place the inner tube 71 in the A positioning hole 831; ④ Insert the expansion rod 84 into the inner tube 71, so that a sealed space is formed between the inner tube 71 and the expansion rod 84; ⑤ Connect the water inlet connector 87 to the external high-pressure water supply device; ⑥ Water enters the sealed space formed by the inner tube 71 and the expansion rod 84 from the water inlet hole 842, and the water pressure is increased to 50MPa through three steps, and the pressure is maintained for 5 seconds. Under the action of high pressure, the inner tube 71 is expanded and forms an integral structure with the liner 73 and the outer tube 71.

[0039] The foregoing general description of the invention and its specific embodiments should not be construed as a limitation on the technical solution of the invention. Those skilled in the art, based on the disclosure of this application, can add, reduce, or combine the disclosed technical features in the foregoing general description and / or specific embodiments (including examples) without departing from the constituent elements of the invention, to form other technical solutions within the scope of protection of this application.

Claims

1. A low-flow transformer high-efficiency oil-air cooler, comprising a cooler body (1), a guide shroud (2) installed on one side of the cooler body (1), a fan (3) installed inside the guide shroud (2), an oil inlet pipe (11) and an oil outlet pipe (12) provided on the cooler body (1), a butterfly valve (4) connected to the oil outlet pipe (12), an oil pump (5) connected to the butterfly valve (4), and a connecting pipe (6) connected to the outlet of the oil pump (5); a set of finned tubes (7) provided between the oil inlet pipe (11) and the oil outlet pipe (12) for heat exchange of the oil; the upper end of the finned tubes (7) is connected to the oil inlet pipe (11) through a branch pipe, and the lower end of the finned tubes (7) is connected to the oil outlet pipe (12) through a manifold; characterized in that: The finned tube (7) comprises an inner tube (71) and an outer tube (72), the outer wall of the outer tube (72) is provided with fins (721), the fins are arranged in a spiral shape on the outer tube (72); a set of lining tubes (73) is arranged between the inner tube (71) and the outer tube (72) and is uniformly distributed in the circumferential direction, the outer surface of the lining tube (73) is in abutment with the outer tube (72) and the inner tube (71) at the same time to form a limiting structure.

2. The low flow transformer oil air cooler of claim 1, wherein: The lining tube (73) is a straight cylinder structure, the cross section of the lining tube (73) is composed of a bottom edge, a top edge and two side edges connecting the bottom edge and the top edge, wherein the bottom edge is in abutment with the inner tube (71) and the top edge is in abutment with the outer tube (72); the bottom edge and the top edge are both in an arc shape, the curvature radius of the bottom edge is equal to the radius of the outer wall of the inner tube, and the curvature radius of the top edge is equal to the curvature radius of the inner wall of the outer tube.

3. The low flow transformer oil air cooler of claim 2, wherein: The bottom edge and the top edge are both connected with the side edge through a round corner structure.

4. The low flow transformer oil air cooler of claim 3, wherein: The top edge is longer than the bottom edge, forming an outer large and inner small structure.

5. The low flow transformer oil air cooler of claim 4, wherein: The number of the lining tubes (73) is 16-24.

6. The low flow transformer oil air cooler of any of claims 1-5, wherein: The manufacturing process of the finned tube (7) is as follows: ①the outer tube (72) is fixedly placed; ②the lining tubes (73) are arranged and placed inside the outer tube (72) and are limited; ③the inner tube (71) is placed at the center inside the outer tube (72); ④the inner tube (71) is expanded, so that the inner tube (71), the lining tube (73) and the outer tube (71) form an integral structure through expansion.

7. The low flow transformer oil air cooler of claim 6, wherein: The fin (721) is formed by extrusion rolling of the outer tube (72).

8. The low flow transformer oil air cooler of claim 6, wherein: The expansion tool for forming the finned tube (7) comprises a support (81), an expansion rod (84), and a pair of outer tube positioning plates (82) and inner tube positioning plates (83); the inner tube positioning plate (83) is arranged outside the outer tube positioning plate (82) and abuts against the outer tube positioning plate (82); the inner tube positioning plate (83) and the outer tube positioning plate (82) are detachably mounted on the support (81); the inner tube positioning plate (83) is provided with A positioning holes (831), the outer tube positioning plate (82) is provided with B positioning holes (821), the center lines of the A positioning holes (831) and the B positioning holes (821) coincide, the inner tube positioning plate (83) is provided with a set of liner tube positioning blocks (832), the expansion rod (84) is provided with a pair of bosses (841), the bosses (841) are sealingly connected with the inner wall of the inner tube (71) when the expansion rod (84) is inserted into the inner tube (71), one end of the expansion rod (84) is provided with a water inlet hole (842), the side surface of the expansion rod (84) is provided with a water outlet hole (843), the water outlet hole (843) is in communication with the water inlet hole (842), the support (81) is detachably connected with a limiting plate (86), the limiting plate (86) abuts against the inner tube positioning plate (83) at the upper end, the limiting plate (86) is provided with a through hole (861), the inner wall of the through hole (861) abuts against the outer wall of the expansion rod (84), the steps for forming the finned tube (7) by the expansion tool include: ① placing the outer tube (72) in the B positioning hole (821); ② arranging and placing the liner tube (73) inside the outer tube (72) and limiting the liner tube (73) by the liner tube positioning block (832); ③ placing the inner tube (71) in the A positioning hole (831); ④ inserting the expansion rod (84) into the inner tube (71); ⑤ inserting the external high-pressure water supply device into the water inlet hole (842); ⑥ expanding the inner tube (71) under the action of water pressure, so that the inner tube (71), the liner tube (73), and the outer tube (71) form an integral structure by expansion.

9. The low flow transformer oil air cooler of claim 8, wherein: One end of the expansion rod (84) provided with the water inlet hole (842) is connected with a water inlet joint (87).

10. The low flow transformer oil air cooler of claim 9, wherein: The boss (841) is provided with a sealing groove, and a sealing ring (85) is sleeved on the sealing groove.

Images