Cold-heat source separated heat-conducting fin based on topological optimization, design method and sensible heat storage unit

Abstract

The application discloses a cold-heat source separated heat-conducting fin based on topological optimization, a design method and a sensible heat storage unit, and belongs to the technical field of heat energy storage. In view of the problems that the existing heat storage fin has low heat transfer efficiency and cannot realize charge-heat and discharge-heat decoupling, the application provides a fin structure which is provided with a space-separated heat source channel cooperation part and a heat sink channel cooperation part, and the fin body presents a non-uniform multi-stage branched topological structure which extends outward from the channel area. The structure is generated based on a topological optimization algorithm which applies manufacturing constraints, realizes physical separation of the charge-heat and discharge-heat processes while meeting the casting process requirements. The application not only significantly improves the effective heat conduction coefficient and the charge-heat and discharge-heat rates, but also supports simultaneous charge-heat and discharge-heat, greatly improving the operation flexibility of the heat storage system.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy storage and heat transfer enhancement technology, specifically relating to a cold and heat source separated heat-conducting fin based on topology optimization, a design method, and a sensible heat storage unit. Background Technology

[0002] With the widespread application of renewable energy sources such as solar and wind power, thermal energy storage technology has become a key component of new power systems to address their volatility and the time mismatch between energy supply and demand. Among various thermal energy storage technologies, sensible heat storage technologies utilizing materials such as concrete and molten salt have attracted much attention due to their low cost and system simplicity. However, these commonly used low-cost thermal energy storage materials generally suffer from the inherent defect of low thermal conductivity, resulting in slow charging and discharging rates, poor power regulation capabilities, and difficulty in responding to rapidly changing load demands.

[0003] To address the aforementioned heat transfer bottlenecks, existing technologies typically employ the method of embedding highly thermally conductive fins (such as straight fins or pin fins) into the heat storage material to enhance heat transfer. However, existing fin technologies suffer from the following main shortcomings:

[0004] 1. Limited design methods and suboptimal heat transfer efficiency: Traditional fin configurations are mostly designed based on experience or simplified geometric models (such as rectangles and circles), failing to perform global optimization based on the actual distribution of the heat flow field. This easily creates "heat transfer dead zones" between the fins and the substrate, resulting in the inability to fully utilize the heat transfer potential within a limited material volume.

[0005] 2. Limited structural function and inability to decouple charging and discharging: Existing fins are typically arranged around a single flow channel (charging and discharging share the same loop), meaning that the charging and discharging processes must alternate and cannot be physically isolated. This structure limits the system from achieving "simultaneous charging and discharging" or rapid switching between charging and discharging modes, severely restricting the flexibility of energy storage systems in complex application scenarios.

[0006] 3. The contradiction between manufacturing process and performance: Some theoretically optimized complex structures often ignore the minimum wall thickness limit of processing technology such as casting, which leads to the inability to manufacture at low cost even if the theoretical performance is good, or the existence of defects after manufacturing that affect the performance.

[0007] Therefore, there is an urgent need for a topology-optimized cold and heat source separated heat-conducting fin, design method, and sensible heat storage unit to solve the problems existing in the current technology. Summary of the Invention

[0008] This invention provides a topology-optimized cold and heat source separated thermal conductive fin, design method, and sensible heat storage unit. It addresses the problems of existing thermal storage fins, which use empirical geometric designs with a single flow channel, resulting in the inability of the system to achieve independent operation (decoupling) of the heat charging and discharging process, and the low equivalent thermal conductivity with limited material usage, thus failing to meet the requirements for efficient and flexible energy storage.

[0009] The core technology of this invention mainly proposes a physical separation of cold and heat source channels, and a design method and sensible heat storage unit with a non-uniform dendritic (or antler-shaped) distribution characteristic generated by a topology optimization algorithm with minimum size constraints.

[0010] In a first aspect, the present invention provides a topology-optimized cold and heat source separation thermal fin, comprising a fin body made of a thermally conductive material;

[0011] The rib body is provided with at least one first channel mating part for mating with a heat source pipe and at least one second channel mating part for mating with a heat sink pipe, the first channel mating part and the second channel mating part being spatially isolated from each other;

[0012] The fin body is constructed as a non-uniform heat-conducting network structure extending outward from the area where the first channel mating part and the second channel mating part are located.

[0013] The non-uniform heat conduction network structure is distributed in a multi-level branched manner, and the distribution density of the solid material of the fin body is higher in the region near the first channel mating part and the second channel mating part than in the region far from the first channel mating part and the second channel mating part.

[0014] Furthermore, the multi-level branching distribution includes a primary trunk and multi-level branches extending from the primary trunk;

[0015] The primary trunk connects between the first channel mating part and the second channel mating part, or surrounds the first channel mating part and the second channel mating part; the cross-sectional area of ​​the multi-level branches gradually decreases from the root near the first channel mating part and the second channel mating part to the distal end.

[0016] Furthermore, the rib body is a structure generated based on a topology optimization algorithm, and the solid feature size of any part of the rib body is greater than or equal to the preset minimum manufacturing constraint size.

[0017] Furthermore, the rib body has a predetermined thickness in the axial direction along the first channel mating part, and the thickness is formed by stretching along the axial direction based on a two-dimensional topology optimization configuration;

[0018] Alternatively, the rib body is a three-dimensional irregular structure formed by direct topology optimization in three-dimensional space.

[0019] Furthermore, the rib body adopts a split splicing structure, including at least a first half and a second half;

[0020] The first half and the second half are connected by fasteners or snap-fit ​​structures to jointly enclose and form the first channel mating part and the second channel mating part, thereby clamping and fixing the rib body to the heat source pipe and the heat sink pipe.

[0021] Furthermore, the connection between the first half and the second half is provided with mounting holes for accommodating bolts or C-type snap-fit ​​structures for interlocking.

[0022] The rib body is roughly symmetrical about the center line connecting the first channel mating part and the second channel mating part.

[0023] In a second aspect, the present invention provides a sensible heat storage unit, comprising:

[0024] The shell is filled with sensible heat storage material.

[0025] At least one heat source pipe and at least one heat sink pipe, the heat source pipe and the heat sink pipe being installed within the casing; and

[0026] Several heat-conducting fins with separate cold and heat sources as described above; several heat-conducting fins are arranged at intervals along the axial direction of the heat source pipe and the heat sink pipe, and are immersed in sensible heat storage material.

[0027] The heat source pipe passes through the first channel of the heat-conducting fin, and the heat sink pipe passes through the second channel of the heat-conducting fin.

[0028] Furthermore, the thermal conductivity of the heat-conducting fin material is greater than 150 W / (m·K), and the sensible heat storage material is a solid heat storage medium;

[0029] The percentage of the volume of the heat-conducting fins relative to the total volume of the sensible heat storage unit is constrained within a preset range.

[0030] Furthermore, the heat source pipe is used to introduce hot fluid during the heat charging process or as an electric heater, and the heat sink pipe is used to introduce cold fluid during the heat release process; the heat-conducting fins are configured to allow the heat charging process and the heat release process to occur independently or simultaneously.

[0031] Thirdly, the present invention provides a design method for a cold and heat source separated heat-conducting fin based on topology optimization as described above, comprising the following steps:

[0032] Establish a computational domain that includes independent heat source regions and heat sink regions;

[0033] The objective function for topology optimization is constructed based on the steady-state heat conduction model. The objective function includes at least one of minimizing the average temperature, minimizing entropy production, or minimizing pyrolysis dissipation, which serves as an approximate proxy for the transient heat charging and discharging process.

[0034] Two-stage topology optimization of the computational domain:

[0035] Phase 1: Optimize at the first grid resolution to generate the initial material density distribution field;

[0036] The second stage: Based on the initial material density distribution field, a secondary optimization is performed under the condition of applying a minimum length scale constraint, which corresponds to the minimum feature size allowed by the manufacturing process.

[0037] Based on the material density distribution after secondary optimization, regions with equivalent material volume fraction greater than a preset threshold are extracted to generate the final geometric configuration of the heat-conducting fins.

[0038] The main contributions and innovations of this invention are as follows:

[0039] 1. Breaking theoretical limits in heat transfer performance and significantly improving heat charge and release rates: With the same material volume ratio (e.g., 10%), the optimized fin structure of this invention achieves an effective thermal conductivity of over 43.23 W / (m·K). This is approximately 20.6 times higher than a finless substrate; approximately 156% higher than traditional rectangular fins; and exceeds the theoretical upper limit of the Hashin-Shtrikman (HS) standard for uniformly mixed materials by approximately 166%. In actual heat release tests, its average heat release power is 8.0% higher than that of rectangular fins, and its outlet temperature is 5.8% higher.

[0040] 2. Achieving physical decoupling and synchronous operation of the charging and discharging processes: This invention innovatively constructs a separate structure containing independent heat sources (such as heating pipes) and heat sinks (such as water pipes). This topology allows charging and discharging to use independent fluid loops without interference, thus solving the bottleneck of traditional single-channel systems that cannot adapt to "charging and discharging simultaneously" or continuous rapid cycle operations, and greatly improving the operational flexibility of the system.

[0041] 3. Balancing high performance and manufacturing feasibility (engineering implementation): This invention introduces a minimum size constraint (such as R) into the optimization algorithm. min =3mm), ensuring that the thickness of the generated rib branches meets the requirements of low-cost processes such as aluminum alloy casting (no minute features). Experiments show that even with manufacturing constraints, its thermal performance only decreases slightly (e.g., from 48.47 to 41.65 W / (m·K)), but while ensuring structural integrity and yield, its performance still far exceeds that of traditional structures, achieving a balance between theoretical optimization and engineering manufacturing.

[0042] 4. Highly efficient design method, reducing computational costs: The design method proposed in this invention uses a steady-state heat conduction model to approximate the computationally intensive transient model for topology optimization. Verification shows that the performance difference between the steady-state optimized structure and the transient optimized structure is less than 1%, but the computational efficiency is improved by about 10 times, significantly reducing the computational barrier for designing complex thermal storage structures.

[0043] Details of one or more embodiments of the present invention are set forth in the following drawings and description, so that other features, objects and advantages of the invention will be more readily understood. Attached Figure Description

[0044] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0045] Figure 1 This is a schematic diagram of the boundary conditions and objective function (steady-state heat conduction model) used in the topology optimization design in this embodiment of the invention.

[0046] Figure 2 This is a schematic diagram of the boundary conditions used to evaluate the effective thermal conductivity in an embodiment of the present invention;

[0047] Figure 3 This is a graph showing the geometric evolution of the heat-conducting fins and the convergence curve of the objective function during the topology optimization iteration process in an embodiment of the present invention.

[0048] Figure 4 This is a bar chart comparing the effective thermal conductivity of the topology-optimized ribs of the present invention with those of no ribs, uniformly mixed materials, and traditional rectangular ribs in embodiments of the present invention.

[0049] Figure 5 The initial material volume fraction in the embodiments of the present invention ( A schematic diagram illustrating the impact of transient heat conduction topology optimization results and effective thermal conductivity;

[0050] Figure 6 This is a comparison chart of topology optimization results based on steady-state and transient heat conduction models in an embodiment of the present invention (mesh size 2mm, showing the configuration and thermal conductivity under different initial distributions and objective functions).

[0051] Figure 7 This is a diagram showing the steady-state heat conduction topology optimization results using a refined mesh (mesh size 1mm) in an embodiment of the present invention (demonstrating a fine branched structure and improved thermal conductivity at a higher resolution).

[0052] Figure 8 In this embodiment of the invention, a minimum manufacturing size constraint (R) is applied. minTopological configuration of the heat-conducting fins after (=3mm);

[0053] Figure 9 This is a comparison diagram of the optimization process and results of the two-stage optimization strategy (fine mesh first, then coarse mesh) adopted in the embodiments of the present invention.

[0054] Figure 10 This is a schematic diagram of three-dimensional thermally conductive fins of different thicknesses formed by axial stretching based on two-dimensional topological results in an embodiment of the present invention;

[0055] Figure 11 These are photographs and assembly diagrams of the heat-conducting fins with a split-type splicing structure used in embodiments of the present invention.

[0056] Figure 12 This is a schematic diagram of three-dimensional heat-conducting fins under different initial distributions generated directly in three-dimensional space in an embodiment of the present invention;

[0057] Figure 13 This is a performance comparison curve of the heat-conducting fins of this invention and existing technical solutions in terms of heat dissipation power and outlet temperature.

[0058] Figure 14 This is a perspective view of the overall structure of the sensible heat storage unit including thermally conductive fins according to an embodiment of the present invention.

[0059] In the diagram, 1 is the heat-conducting fin; 2 is the heat source pipe; 3 is the heat sink pipe; 4 is the heat storage material; 11 is the first half; 12 is the second half; and 13 is the connecting structure. Detailed Implementation

[0060] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with one or more embodiments of this specification. Rather, they are merely examples of apparatuses and methods consistent with some aspects of one or more embodiments of this specification as detailed in the appended claims.

[0061] It should be noted that the steps of the corresponding methods are not necessarily performed in the order shown and described in this specification in other embodiments. In some other embodiments, the methods may include more or fewer steps than described in this specification. Furthermore, a single step described in this specification may be broken down into multiple steps in other embodiments; and multiple steps described in this specification may be combined into a single step in other embodiments.

[0062] Example 1: Structure of heat-conducting fin 1 with separate cold and heat source based on topology optimization

[0063] This embodiment provides a topology-optimized cold and heat source separated thermal conductive fin 1, and its overall application effect in the thermal storage unit is as follows: Figure 14 As shown. This thermally conductive fin 1 is designed to solve the problem of coupled heat transfer processes and low heat transfer efficiency in traditional sensible heat storage systems.

[0064] like Figure 14 As shown, the heat-conducting fin 1 has a plate-like or block-like structure, and is preferably made of a high thermal conductivity metal material, such as 1060 aluminum alloy, copper, or graphite composite material. In this embodiment, an aluminum alloy with a thermal conductivity greater than 150 W / (m·K) is selected. The main body of the heat-conducting fin 1 has two spatially isolated channel mating parts: a first channel mating part and a second channel mating part. The first channel mating part is used to accommodate the heat source pipe 2 (e.g., a tubular heater), and the second channel mating part is used to accommodate the heat sink pipe 3 (e.g., a steel pipe for cooling water). Figure 3 and Figure 11 As shown, these two mating parts are typically represented as two adjacent but separate circular holes with a diameter that matches the corresponding pipe outer diameter (e.g., 25 mm).

[0065] Combination Figure 3 and Figure 8 As shown, the geometric configuration of the heat-conducting fin 1 is not a traditional regular shape (such as a rectangular straight fin), but a non-uniform heat-conducting network structure generated based on a topology optimization algorithm. This structure exhibits a multi-level branching distribution characteristic similar to "dendritic" or "antler-like" structures. Specifically, the solid material of the fin is mainly concentrated in the area connecting the first and second channel mating parts and the surrounding area, forming a robust primary trunk; multi-level branches extend outward from the primary trunk, such as... Figure 3 (As shown in the morphology after 500 iterations), and the cross-sectional area of ​​the branches gradually decreases as they move away from the center of the channel. This non-uniform density distribution allows heat to be transferred from the heat source to the heat storage material 4 with minimal thermal resistance, or to converge from the heat storage material 4 to the heat sink.

[0066] Considering the feasibility of the manufacturing process, especially the requirements of metal casting processes (such as die casting or sand casting), the heat-conducting fin 1 in this embodiment meets the minimum feature size constraint. For example... Figure 8 and Figure 11 As shown, the solid wall thickness of any part of the rib body (including the outermost branch) is greater than or equal to the preset minimum manufacturing constraint dimension R. min Preferably 3mm. (The last part is incomplete and lacks context.) Figure 9 "Initial state" (R) min Compared to the fine structure of (1 mm), Figure 8The structure has fewer and thicker branches, effectively avoiding casting defects. This prevents incomplete casting or internal porosity defects caused by excessively small feature dimensions, ensuring the structure's mechanical strength and thermal conductivity.

[0067] Regarding the three-dimensional morphology of the ribs, this embodiment provides two preferred forms:

[0068] 1. Tensile three-dimensional structures: such as Figure 10 As shown, this structure is formed by stretching a two-dimensional topology optimization configuration along the channel axis. Figure 10 Four configurations with thicknesses H of 20mm, 30mm, 40mm, and 50mm are shown. To balance material cost (volume percentage) and heat transfer performance, and for ease of installation, the fins have a predetermined axial thickness H. This was determined through simulation analysis ( Figure 10 As the thickness increases, the thermal conductivity decreases slightly (from 25.96 to 24.24 W / (m·K)). Considering both structural strength and heat transfer performance, the preferred thickness H is 40 mm, which ensures both structural rigidity and maintains a high equivalent thermal conductivity.

[0069] 2. Direct 3D optimization structure: such as Figure 12 As shown, this illustrates different initial material distributions. The optimized result is characterized by a changing cross-sectional shape along the axial direction (exhibiting spatial irregular features). That is, the structure is an irregular structure formed by direct topology optimization in three-dimensional space, and it also has a non-uniform density change along the axial direction. Although it is slightly more difficult to manufacture, its equivalent thermal conductivity (about 26.60 W / (m·K)) is slightly higher than that of the stretched structure.

[0070] Example 2: Split-type splicing structure and installation method

[0071] To solve the engineering challenge of installing complex irregular fins onto long pipes, this embodiment improves upon the heat-conducting fin 1 in Embodiment 1 by adopting a split design.

[0072] like Figure 11 As shown in the physical diagram, the main body of the heat-conducting fin 1 is divided into a first half 11 and a second half (for example, into upper and lower halves). The first half 11 and the second half 12 respectively contain half of the outline of the first channel mating part and the second channel mating part. During installation, the first half 11 and the second half 12 are placed on both sides of the heat source pipe 2 and the heat sink pipe 3, and then they are joined and tightened by the connecting structure 13.

[0073] Specific connection methods are as follows: Figure 11As shown: A connection structure 13 is pre-installed in the middle of the rib body (i.e., the main area between or near the two pipes). One side can be fastened by bolts passing through pre-set mounting holes and nuts; the other side or both sides can be secured using a C-type snap-fit ​​structure. To reduce contact thermal resistance, thermally conductive putty or thermally conductive silicone grease is applied between the inner walls of the first and second channel mating parts and the outer wall of the pipe. This split structure not only facilitates manufacturing (reducing mold complexity) but also greatly facilitates on-site assembly and maintenance.

[0074] Example 3: Sensible Heat Storage Unit

[0075] This embodiment provides a sensible heat storage unit that utilizes the aforementioned thermally conductive fins 1, such as... Figure 14 As shown.

[0076] The thermal storage unit comprises a rectangular shell (e.g., 1.5m × 0.3m × 0.3m). Figure 14 (Represented by a transparent wireframe in the figure), the interior of the shell is filled with sensible heat storage material 4 (such as solid media such as concrete, sand, refractory bricks or ceramics). At least one heat source pipe 2 (electric heating pipe in the figure) and at least one heat sink pipe 3 (steel pipe in the figure) pass parallel to each other through the center of the shell.

[0077] Several heat-conducting fins 1, as described in Embodiment 1 or Embodiment 2, are arranged at intervals along the axial direction of the pipe and are completely immersed in and covered by the sensible heat storage material 4. Figure 14 As shown, the spacing between the fins is matched with the fin thickness (e.g., both are 40mm), so that the volume ratio of the fin material (aluminum alloy) in the entire thermal storage unit is controlled within a preset range (preferably 5% to 10%).

[0078] The system works as follows:

[0079] The heat charging process: When the heat source pipe 2 is energized or a hot fluid is introduced, the heat is rapidly conducted through the first channel mating part of the heat-conducting fin 1 to the main body of the fin and its various branches, and then diffused into the surrounding heat storage material 4.

[0080] Heat release process: Cold fluid (such as water) is introduced into heat sink pipe 3. The heat in the heat storage material 4 is gathered to the main trunk through the fin branches, and then transferred to the fluid in heat sink pipe 3 through the second channel mating part.

[0081] Decoupled operation: Since the heat source and heat sink are physically separated in space, and the fins provide an optimized heat transfer path, the unit allows the charging and discharging processes to be carried out independently, or even simultaneously (charging and discharging at the same time), without interference, which significantly improves the system's response speed and flexibility.

[0082] Example 4: Design method of thermal fin 1 based on two-stage topology optimization

[0083] This embodiment details the design method for generating the aforementioned geometric configuration of the thermally conductive fin 1. This method is based on the topology optimization theory of the variable density method, combining a steady-state heat conduction approximation with a two-stage filtering strategy. The specific steps are as follows:

[0084] Step S1: Construct a mathematical model for topology optimization

[0085] 1. Establish the computational domain:

[0086] like Figure 1 As shown (especially) Figure 1 (The diagram in 'a' shows the computational domain). A two-dimensional square computational domain Ω is defined (e.g., ...). The structure contains two circular holes, each 25 mm in diameter, representing the heat source and heat sink regions, respectively. Considering the symmetry of the structure, and to save computational resources, only the upper half of the computational domain is modeled, and adiabatic boundary conditions are applied along the axis of symmetry. The topology optimization parameters are shown in Table 1 below.

[0087] Table 1

[0088]

[0089] 2. Define the material interpolation model (SIMP method):

[0090] Introducing design variables That is, the material volume fraction within each finite element mesh element, where Represents thermal storage materials (matrix). Representative fin material (high thermal conductivity medium).

[0091] Thermal conductivity k:

[0092]

[0093] In this embodiment, a linear relationship is taken (p=1), that is: (Unit: W / (m·K));

[0094] Specific heat capacity :

[0095]

[0096] (Unit: J / (kg·K));

[0097] density :

[0098]

[0099] (Unit: kg / m³).

[0100]

[0101] in, To minimize the penalty volume fraction, the penalty exponent is taken as... To promote the formation of 0 / 1 binary resolution.

[0102] 3. Regularization and Projection (Filtering):

[0103] To eliminate the checkerboard effect and control the minimum feature size, the original design variables were... Perform Helmholtz partial differential equation filtering and hyperbolic tangent projection:

[0104] Helmholtz filter equation:

[0105]

[0106] in, The filtered variables, The filter radius is a parameter that directly controls the minimum feature size of the structure.

[0107] Hyperbolic tangent projection:

[0108]

[0109] Among them, the projection slope threshold This step is used to reduce grayscale transition areas and obtain clear structural boundaries.

[0110] Step S2: Construct the objective function (steady-state function replaces transient function)

[0111] Although the actual operating conditions are transient heat charging and discharging, in order to reduce computational costs, this invention innovatively adopts a steady-state heat conduction model as an approximate proxy.

[0112] 1. Setting steady-state boundary conditions: such as Figure 1 As shown in b to d in the figure, this embodiment uses a steady-state model instead. Figure 1 The transient model is shown as 'a' in the figure. The specific steady-state boundary settings are as follows:

[0113] Heat source term: throughout the computational domain A uniformly distributed volumetric heat source is applied internally, with a power density set to [value missing]. .

[0114] Boundary conditions: The outer boundaries of the computational domain are all set to adiabatic (e.g., ...). Figure 1 (As indicated by the "insulation" arrow in the middle).

[0115] Simulated operating conditions:

[0116] Operating condition 1 (simulated heat charging, corresponding to...) Figure 1 In The boundary temperature of the heat source region is constant. Insulation in the heat sink area.

[0117] Operating condition 2 (simulated heat release, corresponding to) Figure 1 In The boundary temperature of the heat sink region is constant. Insulation of the heat source area.

[0118] 2. Defining the Objective Function: To obtain the optimal heat transfer performance, this embodiment constructs three optional steady-state objective functions, such as... Figure 1 As shown in the formulas on the right side of b, c, and d, the optimization objective is the average of working conditions 1 and 2:

[0119] Option A: Minimize the average temperature (preferred option, corresponding to...) Figure 1 (b)

[0120]

[0121] in, and These are the areas of the calculation domains for operating conditions 1 and 2, respectively.

[0122] The overall optimization objective is:

[0123]

[0124] Option B: Minimize entropy production (corresponding to) Figure 1 (c) The objective function aims to reduce irreversible losses in the heat transfer process. The entropy production of operating conditions 1 and 2 is defined as S1 and S2, respectively:

[0125]

[0126] The overall optimization objective is:

[0127]

[0128] Option C: Minimize fire accumulation dissipation (corresponding to) Figure 1 (d) In this context, the objective function, based on fire accumulation theory, aims to optimize heat transfer efficiency. The fire accumulation dissipation for conditions 1 and 2 is defined as follows: and :

[0129]

[0130] The overall optimization objective is:

[0131]

[0132] Reference Figure 6Experimental data show that, based on the results of steady-state optimization ( Figure 6 (The next three lines) and the computationally intensive transient optimization results ( Figure 6 The difference in equivalent thermal conductivity (e.g., 43.68 vs. 44.11 W / (m·K)) is minimal, verifying the effectiveness of this approximation method.

[0133] 3. Apply constraints:

[0134] Volume constraint: The volume fraction of the rib material is limited to a preset ratio. (For example, within 10% or 5%):

[0135]

[0136] Step S3: Execute the two-stage topology optimization strategy

[0137] To satisfy manufacturing constraints while avoiding getting trapped in local optima, a two-stage optimization strategy is adopted to solve the above optimization problem. The specific process and results are as follows: Figure 9 As shown.

[0138] Initial value influence analysis: such as Figure 5 As shown, in conventional optimization, different initial material distributions... (0 to 1) will cause the algorithm to converge to different local optima with significant differences in shape.

[0139] Mesh size influence: such as Figure 7 As shown, using a finer mesh (1 mm) in the steady-state model can yield a more refined structure with more branches and higher thermal conductivity (up to 48.47 W / (m·K)), but these structures are often too fine to be manufactured.

[0140] 1. First stage: Unconstrained / high-resolution optimization

[0141] Parameter settings: Use a fine mesh (e.g., mesh size 1 mm) and set the filter radius to a small value. ).

[0142] Initial guess: Using multiple different uniform initial material distributions (For example Perform multiple independent calculations.

[0143] Objective: This stage aims to generate an initial material density distribution field with superior performance. For example... Figure 9 As shown in the first row, “Initial State”, the structure generated at this stage has very fine multi-level tree-like branches. Although it has excellent performance, it is difficult to cast directly due to its fine features (less than 3mm).

[0144] 2. Second stage: Quadratic optimization with manufacturing constraints

[0145] Parameter settings: Maintain the same mesh division, but increase the filter radius to the lower limit allowed by the manufacturing process. ).

[0146] Initial value propagation: Instead of using a uniform distribution, the optimal material density distribution field obtained from the first stage optimization is directly applied. Figure 9 The first row is used as the initial value for this stage.

[0147] Optimization process: Continue iterating based on this, forcing small branches to merge or thicken. For example... Figure 9 As shown in the second line, “50 iterations”, you can see the small branches gradually merging.

[0148] Final result: until all feature dimensions satisfy Requirements. For example... Figure 9 As shown in the third line of the middle section, "Final State," the final generated structural branches are robust and fully meet the casting requirements.

[0149] Effect: The structural equivalent thermal conductivity generated by this strategy can reach [value missing]. It is better than directly in The result obtained by optimizing from scratch under the given conditions (the latter is only the result obtained by optimizing from scratch under the given conditions) See Figure 8 contrast).

[0150] Of course, you can also perform only one optimization step. However, the effect of one-step optimization is slightly worse, i.e., only... Both options are measures that can be adopted in this plan.

[0151] Step S4: Geometric Reconstruction

[0152] After the optimization iteration converges, a continuously varying material density distribution field (θ value between 0 and 1) is obtained within the computational domain. To obtain a definite geometry suitable for manufacturing, the following reconstruction operation is required:

[0153] 1. Binarization threshold extraction: Set a threshold for material volume fraction. Extracting density field All unit regions are defined as "rib domains" (solid thermally conductive materials); The region is defined as the "thermal storage material domain". This is achieved by extracting... The isosurfaces are used to obtain a clear and smooth two-dimensional geometric profile of the ribs.

[0154] 2. Symmetry Restoration (Mirror Operation): In step S1, to reduce computational costs, only the upper half of the computational domain (i.e., the area above the line connecting the centers of the two pipes) was modeled and optimized. Therefore, the obtained two-dimensional contour is only half of the overall structure. In this step, the extracted two-dimensional geometric contour is rotated 180° around the horizontal centerline of the computational domain (i.e., the line connecting the centers of the two pipes) or mirrored. The mirrored part is then joined with the original part to obtain a complete, centrally symmetric two-dimensional rib topology.

[0155] 3. Three-dimensional solid generation (extrude operation): Based on the complete two-dimensional topology described above, an extrusion operation is performed in the computer-aided design environment along the normal direction perpendicular to the two-dimensional plane (i.e., the pipe's axis). For example... Figure 10 As shown, the stretching length is set to be equal to the predetermined fin thickness H (preferably H = 40 mm in this embodiment). The three-dimensional structure formed after stretching is the final solid model of the heat-conducting fin. This solid model has non-uniform multi-level branching characteristics consistent with the two-dimensional optimization results, and the wall thickness of all branches satisfies... The manufacturing constraints can be directly exported as STL or STEP format files for mold processing.

[0156] Example 5: Method for evaluating effective thermal conductivity

[0157] To quantify performance, this invention defines a method for determining the effective thermal conductivity, the principle of which is as follows: Figure 2 As shown. Figure 2 As shown in the left figure, a transient heat transfer model incorporating the actual fin geometry is established to simulate the total heat absorption over one hour; as... Figure 2 As shown in the right figure, an equivalent homogeneous model is established, and its thermal conductivity is adjusted. This makes the total heat absorption equal to the left Figure 1 To. This is the effective thermal conductivity. All thermal conductivity data in this specification are obtained using this method.

[0158] Example 6: Performance Verification

[0159] To verify the beneficial effects of the present invention, a numerical model was constructed to compare and test the performance of the above embodiments. This embodiment performs a comprehensive performance comparison of the optimized ribs, and the results are referenced. Figure 4 and Figure 13 .

[0160] 1. Improved equivalent thermal conductivity

[0161] like Figure 4 As shown, the effective thermal conductivity is compared under different configurations.

[0162] Pure thermal storage material: only 2W / (m·K).

[0163] Rectangular ribs: 16.83 W / (m·K).

[0164] Hashin-Shtrikman (HS) theoretical upper limit (uniform mixing): 16.27 W / (m·K).

[0165] The topology-optimized rib of this invention has a strength of up to 43.23 W / (m·K).

[0166] As can be seen, with the same material volume ratio, the equivalent thermal conductivity of the topology-optimized fins of this invention reaches 43.23 W / (m·K), which is about 20.6 times higher than that of the finless matrix (2 W / (m·K)); and about 156% higher than that of the traditional rectangular fins (16.83 W / (m·K)); and significantly exceeds the theoretical upper limit of the Hashin–Shtrikman theory for uniformly mixed materials (16.27 W / (m·K)), proving the superiority of the topology.

[0167] 2. Impact of manufacturing constraints

[0168] like Figure 8 As shown, the radius parameter is applied. After manufacturing constraints were imposed, although the rib branches became thicker and the details were reduced, resulting in a slight decrease in the equivalent thermal conductivity from 48.47 W / (m·K) (1 mm mesh) to 41.65 W / (m·K), it was still much higher than that of the traditional structure, proving that the present invention achieved an excellent balance between engineering feasibility and high performance.

[0169] 3. Comparison of charging and discharging performance

[0170] Figure 13 The left figure shows the curve of outlet temperature changing over time. Figure 13 The right figure shows the curve of heat release power changing over time.

[0171] Comparison group settings: The curves in the figure correspond to topology-optimized ribs (red solid line), uniformly mixed materials (blue dashed line), rectangular ribs (black dotted line), and no ribs (purple long dashed line), respectively.

[0172] As can be seen, within a 3-hour heat release cycle, the thermal storage unit employing the topology-optimized fins (solid red line) of this invention:

[0173] The average heat dissipation power is 8.8% higher than that of the uniform mixing scheme and 8.0% higher than that of the rectangular fin scheme.

[0174] The average outlet temperature is 5.8% higher than that of the rectangular fin scheme.

[0175] The outlet fluid temperature remained at 61°C at the end of the heat release, which was better than the 58°C of the control group, indicating that it has higher energy transfer efficiency and thermal quality.

[0176] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementations, and will not be repeated here.

[0177] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0178] The above embodiments are merely illustrative of several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

Claims

1. A heat-conducting fin with separate cold and heat sources based on topology optimization, characterized in that, Includes a fin body, the fin body being made of a thermally conductive material; The rib body is provided with at least one first channel mating part for mating with a heat source pipe and at least one second channel mating part for mating with a heat sink pipe, wherein the first channel mating part and the second channel mating part are spatially isolated from each other. The rib body is constructed as a non-uniform heat-conducting network structure extending outward from the region where the first channel mating part and the second channel mating part are located. The non-uniform heat conduction network structure is distributed in a multi-level branched manner, and the distribution density of the solid material of the rib body in the region near the first channel mating part and the second channel mating part is higher than its distribution density in the region far from the first channel mating part and the second channel mating part. The rib body is generated based on a topology optimization algorithm with minimum manufacturing constraint size applied, and the rib body is approximately symmetrical about the center line connecting the first channel mating part and the second channel mating part.

2. The heat-conducting fin with separate cold and heat sources based on topology optimization as described in claim 1, characterized in that, The multi-level branching distribution includes a primary trunk and multi-level branches extending from the primary trunk; The primary trunk connects between the first channel mating part and the second channel mating part, or surrounds the first channel mating part and the second channel mating part; the cross-sectional area of ​​the multi-level branches gradually decreases from the root near the first channel mating part and the second channel mating part to the distal end.

3. The heat-conducting fin with separate cold and heat sources based on topology optimization as described in claim 1, characterized in that, The rib body is a structure generated based on a topology optimization algorithm, and the solid feature size of any part of the rib body is greater than or equal to the preset minimum manufacturing constraint size.

4. The heat-conducting fin with separate cold and heat sources based on topology optimization as described in claim 1, characterized in that, The rib body has a predetermined thickness in the axial direction along the first channel mating part, and the thickness is formed by stretching along the axial direction based on a two-dimensional topology optimization configuration; Alternatively, the rib body is a three-dimensional irregular structure formed by direct topology optimization in three-dimensional space.

5. A topology-optimized heat-conducting fin with separate hot and cold sources as described in any one of claims 1 to 4, characterized in that, The rib body adopts a split splicing structure, including at least a first half and a second half; The first half and the second half are connected by fasteners or snap-fit ​​structures to jointly enclose and form the first channel mating part and the second channel mating part, thereby clamping and fixing the rib body onto the heat source pipe and the heat sink pipe.

6. A topology-optimized heat-conducting fin with separate hot and cold sources as described in claim 5, characterized in that, The connection between the first half and the second half is provided with mounting holes for accommodating bolts or C-type snap-fit ​​structures for interlocking.

7. A sensible heat storage unit, characterized in that, include: The shell is filled with sensible heat storage material. At least one heat source pipe and at least one heat sink pipe, the heat source pipe and the heat sink pipe passing through the housing; and A plurality of heat-conducting fins with separate cold and heat sources as described in any one of claims 1 to 6; the plurality of heat-conducting fins are arranged at intervals along the axial direction of the heat source pipe and the heat sink pipe, and are immersed in the sensible heat storage material; The heat source pipe passes through the first channel mating part of the heat-conducting fin, and the heat sink pipe passes through the second channel mating part of the heat-conducting fin.

8. The sensible heat storage unit as described in claim 7, characterized in that, The thermal conductivity of the material of the heat-conducting fin is greater than 150 W / (m·K), and the sensible heat storage material is a solid heat storage medium; The percentage of the volume of the thermally conductive fins relative to the total volume of the sensible heat storage unit is constrained within a preset range.

9. The sensible heat storage unit as described in claim 7, characterized in that, The heat source pipe is used to introduce hot fluid during the heat charging process or as an electric heater, and the heat sink pipe is used to introduce cold fluid during the heat release process; the heat-conducting fins are configured to allow the heat charging process and the heat release process to occur independently or simultaneously.

10. A design method for a heat-conducting fin with separate cold and heat sources based on topology optimization as described in claim 1, characterized in that, Includes the following steps: Establish a computational domain that includes independent heat source regions and heat sink regions; A topology optimization objective function is constructed based on a steady-state heat conduction model. The objective function includes at least one of minimizing the average temperature, minimizing entropy production, or minimizing fire accumulation dissipation, which serves as an approximate proxy for the transient charge-discharge process. Two-stage topology optimization is performed on the computational domain: Phase 1: Optimize at the first grid resolution to generate the initial material density distribution field; The second stage: Based on the initial material density distribution field, a secondary optimization is performed under the condition of applying a minimum length scale constraint, which corresponds to the minimum feature size allowed by the manufacturing process; Based on the material density distribution after secondary optimization, regions with equivalent material volume fraction greater than a preset threshold are extracted to generate the final geometric configuration of the heat-conducting fins. The boundary conditions of the steady-state heat conduction model are set as follows: under the heat charging condition, the boundary temperature of the heat source region is constant and the heat sink region is adiabatic; under the heat dissipation condition, the boundary temperature of the heat sink region is constant and the heat source region is adiabatic.

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