Transformer cooling fin with multi-stage affine transformation fractal oil way and radiator

Abstract

The invention discloses a transformer cooling fin with a multi-stage affine transformation fractal oil way and a radiator. The cooling fin comprises an oil inlet area, an oil outlet area, a cooling fin base body, an oil cavity interlayer and the fractal oil way. The radiating fin base body is folded to form an oil cavity interlayer, the oil inlet area is located on the upper portion of the radiating fin, a diffusion multi-stage fractal oil way is arranged in the oil inlet area, the oil outlet area is located on the lower portion of the radiating fin, a convergence multi-stage fractal oil way is arranged in the oil outlet area, the fractal oil way has the characteristics of multi-stage bifurcation and ordered self-affine, the tail section of the oil inlet area is correspondingly connected with the starting section of the oil outlet area, and the oil way is formed by the radiating fin base body in a protruding mode. The hydraulic diameter gradually changes in an equal proportion step by step, and the radiator is formed by arranging a plurality of radiating fins. The radiator has the advantages that the diffusion multi-stage fractal oil way fully reduces oil inlet resistance, enhances oil side heat transfer, forms a wall-attached vortex with spanwise and flow direction components on an air side at the same time, enhances air side heat transfer, and the convergence multi-stage fractal oil way enables oil to be fully and uniformly distributed in an oil cavity interlayer, a better air inlet condition is formed, and the overall energy efficiency of the radiator is improved.

Description

Technical Field

[0001] This invention relates to the field of radiator technology, specifically to a transformer heat sink and radiator with a multi-stage affine transformation fractal oil circuit. Background Technology

[0002] Transformers are key equipment used for high- and low-voltage conversion in long-distance power transmission and transformation systems. They generate a lot of heat during operation. If the heat cannot be dissipated quickly and in a timely manner, the heat accumulation will pose a hidden danger to the safe operation of the equipment and system. Therefore, it is necessary to use efficient heat dissipation technology to cool down the transformer.

[0003] Transformer cooling technology removes heat through transformer cooling oil. The heated oil flows into the heat sinks, where it flows downwards. Multiple heat sinks are arranged side-by-side, forming narrow channels between them for upward airflow. During this counter-current flow, air and cooling oil exchange heat, lowering the oil temperature. The air then flows back into the transformer from the bottom of the heat sinks, completing one cooling cycle. Inside the transformer, some of the heated cooling oil becomes less dense and flows upwards, then into the heat sinks. Within the narrow channels between the heat sinks, the air at the bottom is heated, becomes less dense, and rises. This process creates a natural convection system driven by temperature differences. For larger capacity transformers, higher cooling rates are required. In these cases, natural convection is insufficient, necessitating additional power sources (oil pumps, fans) to accelerate the circulation, but this also generates additional energy consumption. Whether using natural or forced circulation cooling, the performance of the radiator is closely related to the energy flow rate inside and outside the heat sinks, and further closely related to the internal structure of the cooling oil and the external airflow field, and the resulting resistance and heat transfer distribution. In fact, for large-capacity transformers, when a better design can automatically increase the natural convection rate and improve the heat dissipation rate to meet certain requirements, there is no need to add forced circulation, thereby saving system energy consumption.

[0004] Current transformer heat sinks generally employ Euclidean geometry-based design methods, often resulting in parallel straight channels or at most tortuous channels for oil circulation. However, this explicit uniform design often fails to generate ideal flow and heat field distributions in the heat sink area, leading to issues such as unbalanced cooling oil distribution, poor convective heat transfer, and even temperature distortion, severely limiting the improvement of heat sink performance. Therefore, it is essential to invent more efficient transformer heat sinks and radiators to solve these problems. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a transformer heat sink and radiator with a multi-stage affine transformation fractal oil circuit, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A transformer heat sink with multi-stage affine transformation fractal oil circuits consists of a heat sink substrate forming an oil cavity interlayer and fractal oil circuits. The oil cavity interlayer is a hollow cavity with openings at the top and bottom, and its sides are sealed by welding through skirts of the heat sink substrate. Transformer oil is injected through the top opening, with a portion entering the oil cavity interlayer. The fractal oil circuits are divided into an oil inlet zone in the upper half and an oil outlet zone in the lower half. The fractal oil circuits in the oil inlet zone follow a diffusion fractal topology, while those in the oil outlet zone follow a convergence fractal topology.

[0007] Fractal oil circuits possess ordered self-affine properties, consisting of multi-level bifurcation units, each composed of a plumb line segment and an inclined line segment. Multi-level bifurcation refers to the diffusion-type characteristic (one path branching into multiple paths) or the convergence-type characteristic (multiple paths converging into one path) at each fractal node level. The ordered self-affine characteristic means that the bifurcation units of the fractal oil circuit exhibit approximate self-similarity from local to global, and the transformation ratios in different directions are not entirely identical. Furthermore, the iterative function system of the self-affine transformation exhibits monotonically ordered changes with the fractal level, causing the lengths of both the plumb line segment and the inclined line segment of the bifurcation unit to monotonically and orderedly change with increasing fractal level.

[0008] The hydraulic diameter ratio coefficient of the fractal oil passage located in the oil inlet area decreases monotonically at each stage, while the hydraulic diameter ratio coefficient of the fractal oil passage located in the oil outlet area increases monotonically at each stage.

[0009] The path of a fractal oil circuit is defined by the coordinate positions of the end nodes of the bifurcation unit through an affine transformation.

[0010] The final section of the oil inlet channel in the oil inlet area is connected to the starting section of the oil outlet channel in the oil outlet area.

[0011] The fractal oil channels in the oil inlet and outlet zones are axially symmetrical about the horizontal center line of the heat sink.

[0012] The fractal oil path is formed by protrusions in the heat sink base, and the hydraulic diameter of the cross-section gradually changes proportionally.

[0013] The width of the oil cavity interlayer is smaller than the hydraulic diameter of the final section of the oil inlet channel in the oil inlet zone, and also smaller than the hydraulic diameter of the initial section of the oil outlet channel in the oil outlet zone.

[0014] A radiator is formed by arranging multiple transformer heat sinks with multi-stage affine transformation fractal oil circuits.

[0015] The beneficial effects of this invention compared to the prior art are: The technical solution of this invention features a fractal oil path in the oil inlet area, constructed from diffusion-type multi-stage branching units. This significantly reduces the overall flow resistance of the cooling oil in the oil inlet area. Because the width of the oil cavity interlayer is smaller than the minimum diameter of the fractal oil path, the cooling oil spontaneously tends to choose the fractal oil path as its primary downward path, accelerating its flow to the oil outlet area. The fractal oil path in the oil outlet area is constructed from convergent multi-stage fractal units. The node confluence appropriately increases the downward resistance of the cooling oil, providing a certain degree of resistance and relatively increasing the proportion of cooling oil flow descending through the oil cavity interlayer. This improves the uniformity of flow distribution in the oil outlet area, effectively enhancing convective heat transfer and temperature distribution on the oil side. It also indirectly improves the air intake conditions at the bottom, which helps to achieve a uniform temperature distribution between the heat sinks. The oblique oil path can simultaneously form a wall-attached vortex with spanwise and flowwise components on the air side, causing global disturbance to the air-side boundary layer and fully enhancing the convective heat transfer on the air side of the heat sink. Compared with the parallel channel oil path based on Euclidean geometry, which is prone to uneven flow distribution and heat transfer deterioration caused by the pulsation of fluid parameters of the upstream transformer, the ordered self-affine fractal oil path based on fractal geometry is not sensitive to the spatiotemporal pulsation of fluid parameters of the upstream transformer. Even if a large flow distortion occurs, it will be smoothed out by the adaptive mechanism in the fractal oil path, so that the internal and external flow thermal fields of the heat sink exhibit strong performance toughness. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 This is a front view of the heat sink of the present invention.

[0018] Figure 2 This is a top view of the heat sink of the present invention.

[0019] Figure 3 This is a three-dimensional structural diagram of the heat sink of the present invention.

[0020] Figure 4 This is a top view of the heat sink of the present invention.

[0021] In the diagram: 1. Heat sink substrate; 2. Oil cavity interlayer; 3. Fractal oil passage; 4. Oil inlet area; 5. Oil outlet area; 6. Branching unit; 6-1. Vertical section; 6-2. Inclined section; 7-1. First-level fractal channel of oil inlet area; 7-2. Second-level fractal channel of oil inlet area; 7-3. Third-level fractal channel of oil inlet area; 7-4. Fourth-level fractal channel of oil inlet area; 7-5. End section channel of oil inlet area; 8-5. Beginning section channel of oil outlet area; 8-1. First-level fractal channel of oil outlet area; 8-2. Second-level fractal channel of oil outlet area; 8-3. Third-level fractal channel of oil outlet area; 8-4. Fourth-level fractal channel of oil outlet area. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0023] Example like Figure 1 , 2 As shown in Figure 3, a transformer heat sink with a multi-stage affine transformation fractal oil circuit comprises a heat sink substrate 1 forming an oil cavity interlayer 2 and a fractal oil circuit 3. The oil cavity interlayer 2 is a cavity with openings at the top and bottom, and its sides are sealed by welding through the skirts of the heat sink substrate 1. Transformer oil is injected from the top opening, with a portion entering the oil cavity interlayer 2. The fractal oil circuit 3 is divided into an oil inlet zone 4 in the upper half and an oil outlet zone 5 in the lower half. The fractal oil circuit 3 in the oil inlet zone 4 is a diffusion fractal topology, and the fractal oil circuit 3 in the oil outlet zone 5 is a convergence fractal topology.

[0024] Preferably, the heat sink substrate 1 is formed by stamping rectangular metal material. After being closed, an oil cavity interlayer 2 and a fractal oil passage 3 are formed between the two stamped surfaces. The fractal oil passage 3 preferably has a tree-shaped branch structure. The transformer oil in the oil inlet zone 4 flows from the main trunk to the branches step by step, and the transformer oil in the oil outlet zone 5 flows from the branches back to the main trunk step by step. The effect is that the flow resistance in the fractal oil passage 3 in the oil inlet zone 4 is greatly reduced, and the descent of the transformer oil in the oil outlet zone 5 is locally hindered, thereby relatively increasing the flow share in the oil cavity interlayer 2 and improving the uniformity of the oil flow.

[0025] The fractal oil path 3 possesses ordered self-affine characteristics and is composed of multi-level bifurcation units 6. Each bifurcation unit 6 consists of a plumb segment 6-1 and an inclined segment 6-2. Multi-level bifurcation refers to the diffusion-type characteristic where one path branches into multiple paths or the convergence-type characteristic where multiple paths converge into one path at each level of the fractal node. The ordered self-affine characteristic means that the bifurcation units 6 of the fractal oil path 3 have approximately self-similarity from local to global, and the transformation ratios in different directions are not exactly the same. At the same time, the iterative function system of the self-affine transformation exhibits monotonically ordered changes with the fractal level, causing the lengths of the plumb segment 6-1 and the inclined segment 6-2 of the bifurcation unit 6 to exhibit monotonically ordered changes with the increase of the fractal level. The path of the fractal oil path 3 is defined by the coordinate positions of the end nodes of the bifurcation units 6 through ordered affine transformation.

[0026] Preferably, the bifurcation unit 6 has a bifurcation structure, that is, the bifurcation unit 6 of the oil inlet zone 4 is inverted Y-shaped, and the bifurcation unit 6 of the oil outlet zone 5 is Y-shaped. The effect is that the bifurcation structure of the oil inlet zone 4 can better suppress the generation of separation vortices when the transformer oil flows through the bifurcation node, thereby reducing the flow resistance. The bifurcation structure of the oil outlet zone 5 can cause the two oil flows to collide and generate a large momentum reduction when the transformer oil flows through the bifurcation node. By increasing the local resistance, the proportion of oil flow entering the oil cavity interlayer 2 is increased, and the flow uniformity is improved. In addition, the oblique oil passage simultaneously forms a wall-attached vortex with spanwise and flowwise components on the air side. The vortex development and turning timing are appropriate, so that the air-side boundary layer is subjected to global disturbance, which fully enhances the convective heat transfer on the air side of the heat sink.

[0027] In this embodiment, it is preferred that some scaling coefficients in the ordered self-affine transformation parameter matrix form a 1 / 2 geometric sequence, some scaling coefficients form a monotonically increasing arithmetic sequence, and some scaling coefficients remain unchanged. The horizontal translation component forms a monotonically increasing nested arithmetic sequence, and the vertical translation component forms a monotonically increasing arithmetic sequence, forming an ordered affine transformation fractal oil circuit. This makes the length of the vertical segment of each fractal unit form a fixed monotonically decreasing arithmetic sequence, and the height difference of the inclined segment of each fractal unit forms a fixed monotonically decreasing arithmetic sequence. The effect is that after each fractal unit is filled, it forms a symmetrical filling of the heat sink in the spanwise direction, so that the oil flow distribution and temperature field distribution are uniform inside and between the heat sink. The fractal oil circuit 3 is not sensitive to the spatiotemporal pulsation of the upstream transformer fluid parameters. Even if a large flow distortion occurs, it will be smoothed out by the adaptive mechanism in the fractal oil circuit 3, so that the internal and external flow thermal fields of the heat sink exhibit strong performance toughness.

[0028] The hydraulic diameter ratio coefficient of the fractal oil passage 3 located in the oil inlet zone 4 decreases monotonically at each level, while the hydraulic diameter ratio coefficient of the fractal oil passage 3 located in the oil outlet zone 5 increases monotonically at each level. The end section channel 7-5 of the oil inlet zone 4 is connected to the beginning section channel 8-5 of the oil outlet zone 5. Preferably, the hydraulic diameter ratio coefficient of each level of the fractal oil passage 3 is taken to be 1.1~1.5. The plumb section 6-1 and the inclined section 6-2 are included in the proportional calculation and the rounding operation is performed on each level. The process is that as the number of branches of the fractal oil passage 3 located in the oil inlet zone 4 increases, the total flow area increases. As the number of branches of the fractal oil passage 3 located in the oil outlet zone 5 decreases, the total flow area decreases. The effect is that the drag reduction effect of the oil inlet zone 4 and the effect of improving the uniformity of oil flow in the oil outlet zone 5 are enhanced, and it is easy to process.

[0029] The fractal oil paths 3 of the oil inlet zone 4 and the oil outlet zone 5 are axially symmetrical about the horizontal center line of the heat sink. Preferably, in this embodiment, the fractal oil path 3 of the oil inlet zone 4 is a four-stage inverted Y-shape, and the fractal oil path 3 of the oil inlet zone 5 is a four-stage Y-shape. The effect is to form a better oil path filling rate on the surface of the heat sink, so that the heat transfer and temperature distribution are more uniform.

[0030] The fractal oil passage 3 is formed by a protrusion of the heat sink substrate 1. The hydraulic diameter of the cross-section gradually changes proportionally. Preferably, the fractal oil passage 3 starts from the horizontal middle position of the heat sink substrate 1. The cross-section of the fractal oil passage 3 is circular. The diameter of the fractal oil passage 3 in the oil inlet area 4 decreases proportionally at each step, and the diameter of the fractal oil passage 3 in the oil outlet area 5 increases proportionally at each step. The effect is that the oil flow resistance between adjacent end nodes is minimized and it is easy to process.

[0031] The width of the oil cavity interlayer 2 is smaller than the hydraulic diameter of the end section of the oil inlet channel 7-5 of the oil inlet zone 4, and also smaller than the hydraulic diameter of the beginning section of the oil outlet channel 8-5 of the oil outlet zone 5. Preferably, the width of the oil cavity interlayer 2 is not higher than 6mm, and the diameters of the end section of the oil inlet channel 7-5 and the beginning section of the oil outlet channel 8-5 of the fractal oil circuit 3 are higher than 6mm. The effect is to enhance the drag reduction and oil flow uniformity in the oil inlet zone 4 and the oil outlet zone 5, respectively, and indirectly improve the air intake conditions at the bottom. Figure 4 The transformer radiator shown includes heat sinks with multi-stage affine transformation fractal oil channels 3. Preferably, multiple heat sinks of the radiator are arranged in parallel, and the center distance between adjacent heat sinks is not less than the sum of the radius of the first-stage fractal channel 7-1 in the oil inlet area, the thickness of the heat sink substrate 1, and the half-width of the oil cavity interlayer 2. The effect is to provide good development space for the flow direction and spanwise wall-attached eddies formed between the heat sinks, thereby improving the heat transfer effect on the air side.

Claims

1. A transformer heat sink with multi-stage affine transformation fractal oil circuit, wherein an oil cavity interlayer (2) and a fractal oil circuit (3) are formed by the closure of a heat sink substrate (1); characterized in that: The oil cavity interlayer (2) is a cavity with openings at the top and bottom. The sides are sealed by welding through the skirt of the heat sink substrate (1). Transformer oil is injected from the top opening, and part of it enters the oil cavity interlayer (2). The fractal oil passage (3) is divided into an oil inlet area (4) in the upper part and an oil outlet area (5) in the lower part. The fractal oil passage (3) in the oil inlet area (4) is a diffusion fractal topology, and the fractal oil passage (3) in the oil outlet area (5) is a convergence fractal topology. The fractal oil path (3) has ordered self-affine characteristics and is composed of multi-level bifurcation units (6). The bifurcation unit (6) is composed of a plumb segment (6-1) and an inclined segment (6-2). Multi-level bifurcation refers to the diffusion type of one path branching into multiple paths or the convergence type of multiple paths converging into one path at each level of fractal node. The ordered self-affine characteristic means that the bifurcation unit (6) of the fractal oil path (3) has approximately self-similarity from local to global, and the transformation ratios in different directions are not completely the same. At the same time, the iterative function system of the self-affine transformation changes monotonically and orderly with the fractal level, so that the length of the plumb segment (6-1) and the length of the inclined segment (6-2) of the bifurcation unit (6) both change monotonically and orderly with the increase of the fractal level. The path of the fractal oil path (3) is defined by the coordinate position of the end node of the bifurcation unit (6) through ordered affine transformation. The hydraulic diameter ratio coefficient of the fractal oil passage (3) located in the oil inlet zone (4) decreases monotonically at each level, while the hydraulic diameter ratio coefficient of the fractal oil passage (3) located in the oil outlet zone (5) increases monotonically at each level. The end section (7-5) of the oil inlet zone (4) is connected to the beginning section (8-5) of the oil outlet zone (5).

2. The transformer heat sink with multi-stage affine transformation fractal oil circuit as described in claim 1, characterized in that: The fractal oil passage (3) of the oil inlet zone (4) and the oil outlet zone (5) is axially symmetrical about the horizontal center line of the heat sink.

3. The transformer heat sink with multi-stage affine transformation fractal oil circuit as described in claim 2, characterized in that: The fractal oil path (3) is formed by a protrusion of the heat sink substrate (1), and the hydraulic diameter of the cross-section gradually changes proportionally.

4. The transformer heat sink with multi-stage affine transformation fractal oil circuit as described in claim 3, characterized in that: The width of the oil cavity interlayer (2) is smaller than the hydraulic diameter of the end section channel (7-5) of the oil inlet zone (4), and also smaller than the hydraulic diameter of the beginning section channel (8-5) of the oil outlet zone (5).

5. A transformer radiator with a multi-stage affine transformation fractal oil circuit, characterized in that, It includes a heat sink as described in any one of claims 1 to 4.

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