A design method of fin free growth micro-channel heat exchanger

Abstract

The application discloses a kind of microchannel heat exchanger design methods of free growth of fin, comprising: after determining the starting point of fin in microchannel and the center of each cross section, determine design area;According to closed Bezier curve and Rodrigues rotation formula, determine the control point of design area;According to control point, material physical property parameter determined according to heat dissipation demand and boundary condition, construct convection-heat exchange analysis model and optimization model;According to grey wolf optimization algorithm, the convection-heat exchange analysis model and optimization model are iteratively solved, and the optimal parameter set is obtained, and microchannel heat exchanger is designed according to the optimal parameter set.The fin of microchannel heat exchanger designed by the application has flexible starting point, cross section and direction;Optimization is carried out by using grey wolf optimization algorithm to determine the parameters of optimal parameter set, and the optimization target is microchannel pressure drop and microchannel bottom surface average temperature, and free growth fin can maintain excellent heat transfer performance within a certain speed range.

Description

Technical Field

[0001] This invention belongs to the field of microchannel heat dissipation technology, specifically relating to a design method for a microchannel heat exchanger with freely growing fins. Background Technology

[0002] In recent years, the rapid development of integrated circuits and artificial intelligence chips has led to both miniaturization and performance improvements, resulting in a significant increase in energy consumption and heat flux density. The heat flux density of some advanced components has approached or even exceeded 1000 W / cm². 2 Excessive heat buildup is detrimental to device stability. Statistics show that for every 1 degree Celsius increase in the operating environment, the reliability of electronic devices decreases by 5%. Therefore, the rapid development of cutting-edge technologies presents significant challenges to heat dissipation. The heat dissipation problem under ultra-high heat flux densities is unprecedentedly severe, urgently requiring more effective heat dissipation solutions to ensure the continued improvement of high-performance electronic devices.

[0003] Since Tuckerman and Pease first proposed microchannels in 1981, they have demonstrated remarkable potential and undergone significant development over the past four decades. Compared to heat exchangers of conventional size, microchannels offer a more compact structure, larger heat transfer area, greater heat transfer capacity, and higher efficiency. They are particularly suitable for operating environments with limited structural space and high local heat flux density, such as integrated circuits, artificial intelligence computing chips, and fuel cells. However, a drawback is the increased pressure difference between the inlet and outlet, necessitating a more powerful pump. In recent years, a significant amount of research has focused on exploring novel geometries for microchannels, including new channel shapes, fins and ribs, uneven surfaces, multilayer structures, and bio-inspired topologies, aiming to achieve higher heat transfer performance while minimizing pressure loss.

[0004] Among these structural innovations, fins are one of the most extensively studied. As effective flow disruptors, fins destabilize flow, break continuous boundary layers, and thus promote fluid mixing. Furthermore, they increase the effective heat transfer area. These combined mechanisms are highly advantageous for improving the thermal performance of microchannels. Simultaneously, fins can be perfectly integrated with other innovative geometries such as cavities. Therefore, parameters such as fin geometry, cross-sectional profile, and arrangement are continuously studied to achieve superior heat transfer performance. However, existing research on fins is mainly limited to simple geometries with finned design parameters, often resulting in large pressure drops and the creation of flow dead zones at the tail, severely limiting the potential for shape variation. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a design method for a microchannel heat exchanger with freely growing fins.

[0006] The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides a design method for a microchannel heat exchanger with freely growing fins, the method comprising: determining the starting point of the fin in the microchannel according to a preset discrimination coefficient and the microchannel size of the microchannel heat exchanger, and obtaining the center of each cross-section of the fin according to the starting point and the normal vector of each cross-section of the fin; The design area is determined based on the center of each cross-section of the rib; The control points of the design region are determined based on the closed Bézier curve and the Rodriguez rotation formula. Determine the material properties and boundary conditions based on heat dissipation requirements; Based on the control points, material properties, and boundary conditions, a convection-heat transfer analysis model and an optimization model are constructed; wherein, the optimization objectives of the convection-heat transfer analysis model and the optimization model are the microchannel pressure drop and the average temperature of the microchannel bottom surface; The convection-heat transfer analysis model and the optimization model are iteratively solved using the Grey Wolf optimization algorithm to obtain the optimal parameter set, and the microchannel heat exchanger is designed based on the optimal parameter set.

[0007] Optionally, the starting point is represented as follows: ; in, Indicates the starting point, This represents the three-dimensional coordinates of the starting point in the Cartesian coordinate system. Represents the origin point. The transition variable is obtained based on the preset discriminant coefficients. Let be the three-dimensional coordinates of the original point in the Cartesian coordinate system.

[0008] Optionally, the transition variable obtained based on the preset discriminant coefficient is represented as follows: ; in, This represents the preset discrimination coefficient.

[0009] Optionally, the normal vectors of each cross-section of the rib are represented as follows: ; in, Indicates the first rib The normal vector of each cross section, The number of cross-sections of the ribs. Let be the component in the x-direction in the Cartesian coordinate system. Let be the component in the y-direction in the Cartesian coordinate system. Let be the component in the Z direction in the Cartesian coordinate system, and .

[0010] Optionally, the center of each cross-section is represented as follows: ; in, Indicates the first rib The center of the cross-section, This refers to the length of the rib.

[0011] Optionally, determining the control points of the design region based on the closed Bézier curve and the Rodriguez rotation formula includes: The initial cross-sectional expression of the rib is constructed based on the closed Bézier curve; Calculate the corresponding slope based on the coordinates of each preset control point; The control points are arranged in descending order according to the slope to obtain a reordered control point; The final control points of the design area are obtained by rotating the reordered control points using the Rodriguez rotation formula.

[0012] Optionally, the convection-heat transfer analysis model and optimization model are expressed as follows: ; in, Indicates the first The first rib in the rib One control point, Indicates the first The first rib in the rib The normal vector of each cross section, Indicates the first The center point of each rib Indicates the first The preset discrimination coefficient of each rib, Represents the parameter set The microchannel pressure drop below Represents the parameter set Average temperature of the bottom surface of the microchannel. Design area for control points The design region for the normal vector. The design area for the origin point. The boundary conditions are as follows. This represents the governing equation.

[0013] Optionally, the step of iteratively solving the convection-heat transfer analysis model and the optimization model using the Grey Wolf optimization algorithm to obtain the optimal parameter set includes: Initialize the gray wolf population for the gray wolf optimization algorithm, and set each gray wolf individual in the gray wolf population as a set of parameters for the convection-heat transfer analysis model and the optimization model; Calculate the fitness value for each individual gray wolf; Perform non-dominated sorting based on the fitness value of each individual gray wolf, and select at least one leader wolf for the current iteration from the sorted gray wolf individuals according to the Pareto front, and update the positions of the remaining gray wolf individuals. When the preset number of iterations is reached, output at least one leader wolf in the Pareto front of the current iteration round as the optimal parameter set.

[0014] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects: In the above technical solution, the present invention uses a model constructed with material property parameters and boundary conditions to obtain the optimal parameter set to construct a free-growing rib with flexible starting point, cross section and direction; under different heat source conditions, the Grey Wolf optimization algorithm is used to optimize to determine the parameters of the optimal parameter set. The optimization objectives are the microchannel pressure drop and the average temperature of the bottom surface of the microchannel, so that the free-growing rib can maintain excellent heat transfer performance within a certain speed range.

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a flowchart of a microchannel heat exchanger design method with freely growing fins provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a microchannel heat exchanger provided in an embodiment of the present invention; Figure 3 This is a schematic diagram showing the optimization frontier and comparison under a uniform heat source provided by an embodiment of the present invention; Figure 4 This is a schematic diagram showing the optimization frontier and comparison under a non-uniform heat source provided by an embodiment of the present invention; Figure 5 This is a schematic diagram of pressure and bottom surface temperature distribution under a uniform heat source provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of a vortex structure under a uniform heat source provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the eddy current, pressure, and bottom surface temperature distribution of a freely growing rib under a non-uniform heat source, provided by an embodiment of the present invention. Figure 8 This is a schematic diagram of pressure drop, heat exchange area and average bottom surface temperature under different inlet flow velocities provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the isotherm of a heat exchanger with different fin structures provided in an embodiment of the present invention. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0018] Figure 1 This is a flowchart of a microchannel heat exchanger design method with freely growing fins provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the method may include the following steps: S101. Determine the starting point of the fin in the microchannel according to the preset discrimination coefficient and the microchannel size of the microchannel heat exchanger, and obtain the center of each cross-section of the fin according to the starting point and the normal vector of each cross-section of the fin.

[0019] Understandable, Figure 2 This is a schematic diagram of the structure of a microchannel heat exchanger provided in an embodiment of the present invention, as shown below. Figure 2 As shown, considering the current core hot issues of chips, 100W / cm 2 The normal heat flux and 500W / cm 2 This study focuses on the structural design and performance evaluation of microchannel heat exchangers operating under laminar flow conditions, combining high heat flux with heat exchanger design. The heat exchanger consists of a series of uniform rectangular channels, each 10 mm × 10 mm in size, with coolant flowing in from one side, passing through fins, and then flowing out from the other side.

[0020] The shape generation of the ribs is controlled by a parametric algorithm. The starting point is determined by both the initial point and the discriminant coefficient. The initial point determines the possible attachment surfaces (sidewall or bottom), while the discriminant coefficient determines the specific location of the starting point. The rib morphology is determined by... It consists of a cross section and a normal vector. The cross section shape is parameterized using Bézier curves, each controlled by eight control points. In addition, two auxiliary points are introduced to ensure geometric continuity at the connection interface.

[0021] To allow for two starting point locations (sidewall or bottom) and to enable switching between them during migration, an initial point can be introduced. O n This point can be located at any three-dimensional position within the fluid domain. The final... O n At the bottom or sidewall, the decision is determined by a preset discrimination coefficient. When the ribs grow freely, the starting point is at the bottom; otherwise, it is at the sidewall. The transition variables obtained according to the preset discrimination coefficients are expressed as follows: ; in, Indicates the preset discrimination coefficient; The starting point of the growing ribs is indicated as follows: ; in, Indicates the starting point. This represents the three-dimensional coordinates of the starting point in the Cartesian coordinate system. Represents the origin point. The transition variable is obtained based on the preset discriminant coefficients. The original point has three-dimensional coordinates in the Cartesian coordinate system. The orientation of freely growing ribs is controlled by the normal vector and the center point of the cross-section. Each rib has... Each cross section has the following parameters: .in, Perpendicular to the bottom surface or side wall, as shown below: ; The normal vectors of each cross section of the rib are represented as follows: ; in, Indicates the first rib The normal vector of each cross section, The number of cross-sections of the ribs. Let be the component in the x-direction in the Cartesian coordinate system. Let be the component in the y-direction in the Cartesian coordinate system. Let be the component in the Z direction in the Cartesian coordinate system, and Specifically, if the ribs grow from the bottom surface, The third component is always 1.

[0022] Therefore, the last rib (located in the cross-section) and (between) can present a maximum tilt angle of 55°.

[0023] The center of the rib's cross-section can be calculated iteratively using the starting point and the normal vector. Therefore, the center of each cross-section is represented as follows: ; in, Indicates the first rib The center of the cross-section, For the length of the rib, It depends on the direction of the ribs. Indicates the width of the fluid domain. Indicates the height of the fluid domain.

[0024] S102. Determine the design area based on the center of each cross-section of the rib.

[0025] It is understandable that, with the center of each cross-section Centered on, the pre-designed area length is Width is The rectangular area is defined as the design area for control points. Once the control points are determined within this area, the cross-sectional geometry can be constructed.

[0026] S103. Determine the control points of the design area based on the closed Bézier curve and the Rodriguez rotation formula.

[0027] Optionally, S103 may include: The initial cross-sectional expression of the rib is constructed based on the closed Bézier curve; Calculate the corresponding slope based on the coordinates of each preset control point; The control points are arranged in descending order according to the slope, resulting in a reordered control point; The final control points of the design area are obtained by rotating the reordered control points using the Rodriguez rotation formula.

[0028] It is understandable that the cross-section of a freely growing rib is constructed from a closed Bézier curve. Its representation on the horizontal plane is as follows: ; in, It is the first The coordinates of the control points; It is a Bernstein polynomial, and its domain is The Bernstein polynomial is represented as follows: ; In reality, the control points of a Bézier curve are arranged in a specific order. When the positions of these control points change, their order is disrupted, leading to severe geometric self-intersections. This makes the resulting profile unsuitable as a cross-section. To address this issue, the slope of each control point relative to the starting point can be calculated, ensuring that they are monotonically decreasing. This way, closed curves can avoid self-intersections.

[0029] The slope is calculated as follows: ; in, , These are the coordinates of the control points. , These are the coordinates of the first control point.

[0030] The slope values ​​are sorted in descending order, and the control points are rearranged accordingly to obtain reordered control points that match the sorted slopes.

[0031] The curvature of a closed Bézier curve exhibits discontinuities (or abrupt transitions) at the starting point. To ensure smoothness, auxiliary points are introduced near the starting point. The x-coordinates of these points are the same as those of the starting point, while their y-coordinates are calculated as the average of the two adjacent points.

[0032] At this point, each smooth curve is controlled by 10 points. To construct the spatial cross-sectional profile, the 10 points on the reference plane are mapped to the target plane using the Rodriguez rotation formula, as shown below.

[0033] ; in, This represents a unit vector.

[0034] Rotation axis and rotation angle It is expressed as follows: ; ; in, The normal vector of the reference plane, is the normal vector of the target plane.

[0035] The final control points obtained after rotation are represented as follows: ; In this way, the final control points of the design area are obtained. Substituting these final control points into the formula for the cross-section of the freely growing ribs generates each unique cross-section. Subsequently, starting points are extracted from each cross-section, and guide curves are constructed using the same method, thus establishing the skeleton of the freely growing ribs. Finally, the solid geometry is constructed through a geometric lofting process.

[0036] S104. Determine the material properties and boundary conditions based on heat dissipation requirements.

[0037] Understandably, considering the difficulty of fabricating irregularly shaped structures, copper was chosen as the material for the heat exchanger to preserve the possibility of 3D printing. The heat exchanger consists of 33 rectangular channels, with deionized water as the coolant. The coolant enters the channels from one side and flows out from the other side via heat dissipation fins, achieving heat exchange. Notably, the design and analysis of the fins were performed only within one channel. After the design was completed, the entire heat exchanger was analyzed.

[0038] When designing the fins, the inlet coolant flow rate of the channel is... V inThe inlet coolant velocity of the channel is 1 m / s. In the analysis of the fins, to study the effect of different flow velocities, the inlet coolant velocity is... V in The speed is 1~2 m / s. The temperature of the coolant at the inlet is... T in It is 293.15K. Export pressure. P out The value is 0. For the heat exchanger, the heat source in the central region (2mm × 2mm) is 500W / cm². 2 The surrounding heat source is 100W / cm². 2 This corresponds to the chip's heat dissipation problem, which is a core hotspot. Simultaneously, the uneven heat source divides the heat exchanger channels into two categories: one is the edge channel, with a heat source of 100W / cm². 2 One type of channel is centered at 100W / cm 2 Based on the heat source, the heat source at the center 2mm × 0.2mm has a heat output of 500W / cm². 2 .

[0039] In the design and analysis of the fins, the walls of the channels in contact with the outside are all thermally insulated. When analyzing the heat exchanger, the walls of the heat exchanger in contact with the outside are also thermally insulated, as shown in the following formula: ; in, Let be the outward normal vector on the boundary. Heat flux density represents the amount of heat passing through a unit area per unit time.

[0040] S105. Construct convection-heat transfer analysis and optimization models based on control points, material properties, and boundary conditions; the optimization objectives of the convection-heat transfer analysis and optimization models are the microchannel pressure drop and the average temperature of the microchannel bottom surface.

[0041] Understandably, the numerical solution is based on the following assumptions: the fluid flow and heat transfer process is three-dimensional steady-state; the fluid is incompressible laminar flow; the effects of gravity and viscous dissipation terms are neglected; only heat conduction and convection are considered, while the effects of thermal radiation are ignored; the material properties are stable and do not change with temperature. Based on the control points, material properties, and boundary conditions, a convection-heat transfer analysis model and an optimization model are constructed, as follows: ; in, Indicates the first The first rib in the rib One control point, Indicates the first The first rib in the rib The normal vector of each cross section, Indicates the first The center point of each rib Indicates the first The preset discrimination coefficient of each rib, Represents the parameter set The microchannel pressure drop below Represents the parameter set Average temperature of the bottom surface of the microchannel. Design area for control points The design region for the normal vector. The design area for the origin point. For boundary conditions, This refers to the governing equations, specifically the governing equations for flow and heat transfer (mass conservation equation, momentum conservation equation, and energy conservation equation).

[0042] S106. The convection-heat transfer analysis model and the optimization model are iteratively solved using the Grey Wolf optimization algorithm to obtain the optimal parameter set, and a microchannel heat exchanger is designed based on the optimal parameter set.

[0043] Optionally, S106 may include: Initialize the gray wolf population for the gray wolf optimization algorithm, and set each gray wolf in the population as a set of parameters for the convection-heat transfer analysis model and the optimization model; Calculate the fitness value for each individual gray wolf; Perform a non-dominated sort based on the fitness value of each individual gray wolf, and select at least one leader wolf for the current iteration from the sorted gray wolves according to the Pareto front, and update the positions of the remaining gray wolves. When the preset number of iterations is reached, output at least one leader wolf in the Pareto front of the current iteration round as the optimal parameter set.

[0044] For example, the optimization algorithm is the Grey Wolf Optimization Algorithm, with a wolf pack size of 40 and 60 iterations. Each complete optimization contains 2400 optimization results. The top three best results of each iteration influence the wolf pack in the next iteration, causing it to approach better results.

[0045] Specifically, during numerical analysis, the solver's convergence condition for temperature and pressure is less than 10. -3 The model is solved based on the mass conservation equation, momentum conservation equation, and energy conservation equation. The objective functions are the pressure drop and the average temperature at the bottom surface, respectively: ; ; in, Indicates inlet pressure, This indicates export pressure. It is the temperature of the unit. The surface is a micro-element. To calculate the average temperature of the surface, the temperature on the micro-element is integrated and then divided by the area to obtain the average temperature of the bottom surface. Meanwhile, to clearly demonstrate the three-dimensional vortex structure generated by the ribs, a [missing information - likely a specific method or technique] was used. Q Standard method. Based on velocity gradient tensor ( The decomposition of u) represents the local equilibrium relationship between shear strain rate and vortex intensity. Its calculation formula is: ; The iterative solution process for the convection-heat transfer analysis model and optimization model based on the gray wolf optimization algorithm is as follows: First, initialize the gray wolf population, with each individual representing a set of control parameters for freely growing fins; calculate the fitness value of each individual in the population; perform non-dominated sorting, if individual A is superior to or equal to individual B in both pressure drop and temperature, and at least one of them is strictly superior to B, then A is determined to dominate B. Store all non-dominated solutions in the population into a new solution set, forming the current Pareto front. If the new solution set is full, calculate the crowding distance of the solutions, remove densely distributed solutions, and retain sparsely distributed solutions to maintain the diversity of the solution set; select three leader wolves from the current Pareto front, update the positions of the remaining gray wolves, and generate new combinations of geometric parameters to update the positions; determine whether the maximum number of iterations has been reached. If not, return to the step of calculating the fitness value of each individual in the population; if so, output the Pareto front as the final optimal design scheme set.

[0046] In one implementation, the effectiveness of the design method is verified by comparing the analysis results under different conditions. To verify the superior performance of the proposed design, a comparative analysis was conducted with several typical structures (including smooth microchannels (SM), cylindrical ribs (CR), equilateral triangles (TRF), inverse triangles (TRB), and rectangular (W = H) ribs (RR)) under the same boundary conditions.

[0047] The free-growing fin design method of the microchannel heat exchanger of the present invention can be further illustrated by simulation examples: Simulation parameters: Channel structural dimensions: Channel length L hs =10mm, channel width W hs =10mm, flow channel width W f =0.2mm, channel height H f =0.4mm. The design domain Ω length of the rib. L do =0.4mm, widthW do =0.2mm. The microchannel material is metallic copper, with the following physical properties: thermal conductivity λ s = 387.6 W / (m·K), density ρ s = 8978kg / m 3 Constant pressure heat capacity C p_s = 381 J / (Kg·K); the coolant used is deionized water, with the following physical properties: thermal conductivity λ f = 0.6 W / (m·K), density ρ f = 998.2 kg / m 3 Constant pressure heat capacity C p_s = 4182 J / (Kg·K), dynamic viscosity μ f = 0.001003 Pa·s.

[0048] To achieve a good balance between complexity and the integrity of geometric representation, the number of cross sections of the free-growing ribs is set to 3, with 2 ribs in each channel.

[0049] Simulation content and results: Figure 3 This is a schematic diagram illustrating the optimization frontier and comparison under a uniform heat source, provided by an embodiment of the present invention. Figure 4 This is a schematic diagram illustrating the optimization frontier and comparison under a non-uniform heat source provided by an embodiment of the present invention, as shown below. Figure 3 and Figure 4 As shown, in the optimization under both heat sources, the freely growing fins consistently maintain an advantage in terms of temperature and pressure drop. Based on the degree of pressure drop variation in the Pareto front solution, the first optimal solution under a uniform heat source and the second optimal solution under a non-uniform heat source are selected for analysis. In the table, TRF represents an equilateral triangular fin, TRB an inverted triangular fin, CR a circular fin, RR a rectangular fin, SM a smooth channel, GR a freely growing fin under a uniform heat source, and FGR a freely growing fin under a non-uniform heat source. Specific parameters are shown in Tables 1, 2, and 3.

[0050] Table 1

[0051] Table 2

[0052] Table 3

[0053] Figure 5 This is a schematic diagram of pressure and bottom surface temperature distribution under a uniform heat source provided by an embodiment of the present invention, as shown below. Figure 5 As shown, in the pressure distribution, compared to the phased increases in other results, the pressure transition of the freely growing ribs is smooth, and the maximum pressure is significantly reduced. Meanwhile, in the temperature distribution, the temperature increase in the first half is significantly delayed.

[0054] Figure 6 This is a schematic diagram of a vortex structure under a uniform heat source provided in an embodiment of the present invention, as shown below. Figure 6 As shown, the freely grown ribs significantly improve the vortex structure. Compared to the horseshoe-shaped vortices of the other four types of ribs, the vortices of the freely grown ribs are more elongated and have virtually no dead zones. Correspondingly, along the streamline of the cross-section, the coolant velocity changes gradually after flowing past the ribs, still retaining sufficient dynamics, further demonstrating its effective elimination of flow dead zones.

[0055] Figure 7 This is a schematic diagram of the eddy current, pressure, and bottom surface temperature distribution of a freely growing fin under a non-uniform heat source, provided by an embodiment of the present invention. Figure 7 As shown, under non-uniform heat sources, freely growing fins can still create a narrow vortex structure, thus maintaining the advantage of low pressure drop. Simultaneously, due to the change in the growth starting point, the fins can further enhance the heat transfer effect, significantly reducing their maximum temperature.

[0056] Figure 8 This is a schematic diagram illustrating the pressure drop, heat transfer area, and average bottom surface temperature under different inlet flow velocities provided in an embodiment of the present invention, as shown below. Figure 8 As shown, under different flow rates and with both heat sources, the structure with freely grown fins maintains the advantage of low pressure drop, only higher than that of smooth channels. Simultaneously, its heat transfer area is also superior to other finned structures, resulting in better heat transfer performance, especially under non-uniform heat source conditions.

[0057] Figure 9 This is a schematic diagram of isotherms of a heat exchanger with different fin structures provided in an embodiment of the present invention, such as... Figure 9 As shown, the heat exchanger with freely growing fins has significantly fewer hot spots than the other structures.

[0058] The fins constructed in this invention possess three characteristics: free starting point, free cross-section, and free direction. Each characteristic is controlled by independent parameters, enabling the iteration of the optimal fin structure based on specific heat source distribution, inlet and outlet conditions, and objective function. This results in higher structural freedom, better adaptability to actual working conditions, and a more general and widely applicable design method. It significantly improves the vortex structure created by the fins, enhances the turbulence effect, reduces the flow dead zone around the fin structure, lowers the flow resistance of the fins, and reduces the pressure drop at both ends of the channel. Furthermore, it fully utilizes the surface area for heat exchange, reducing the average temperature of the channel bottom surface and thus lowering the peak temperature of the heat exchanger. This invention is applicable not only to fin structures in conventional microchannels but also to needle-fin arrays sweeping across flat plates and irregularly shaped baffles in manifold microchannels, providing a reference for innovative methods of turbulence structures.

[0059] It should be noted that the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0061] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings and the disclosure in carrying out the claimed invention. In the description of the invention, the word "comprising" does not exclude other components or steps, "a" or "an" does not exclude a plurality, and "a plurality" means two or more, unless otherwise explicitly specified. Furthermore, while different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce good results.

[0062] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A design method for a microchannel heat exchanger with freely growing fins, characterized in that, The method includes: The starting point of the fin in the microchannel is determined according to the preset discrimination coefficient and the microchannel size of the microchannel heat exchanger, and the center of each cross-section of the fin is obtained according to the starting point and the normal vector of each cross-section of the fin. The design area is determined based on the center of each cross-section of the rib; The control points of the design region are determined based on the closed Bézier curve and the Rodriguez rotation formula. Determine the material properties and boundary conditions based on heat dissipation requirements; Based on the control points, material properties, and boundary conditions, a convection-heat transfer analysis model and an optimization model are constructed; wherein, the optimization objectives of the convection-heat transfer analysis model and the optimization model are the microchannel pressure drop and the average temperature of the microchannel bottom surface; The convection-heat transfer analysis model and the optimization model are iteratively solved using the Grey Wolf optimization algorithm to obtain the optimal parameter set, and the microchannel heat exchanger is designed based on the optimal parameter set. The step of determining the control points of the design region based on the closed Bézier curve and the Rodriguez rotation formula includes: The initial cross-sectional expression of the rib is constructed based on the closed Bézier curve; Calculate the corresponding slope based on the coordinates of each preset control point; The control points are arranged in descending order according to the slope to obtain a reordered control point; The final control points of the design area are obtained by rotating the reordered control points using the Rodriguez rotation formula.

2. The design method for a microchannel heat exchanger with freely growing fins according to claim 1, characterized in that, The starting point is represented as follows: ； in, Indicates the starting point, This represents the three-dimensional coordinates of the starting point in the Cartesian coordinate system. Represents the origin point. The transition variable is obtained based on the preset discriminant coefficients. Let be the three-dimensional coordinates of the original point in the Cartesian coordinate system.

3. The design method for a microchannel heat exchanger with freely growing fins according to claim 2, characterized in that, The transition variable obtained based on the preset discriminant coefficient is represented as follows: ； in, This represents the preset discrimination coefficient.

4. The design method for a microchannel heat exchanger with freely growing fins according to claim 3, characterized in that, The normal vectors of each cross section of the rib are represented as follows: ； in, Indicates the first rib The normal vector of each cross section, The number of cross-sections of the ribs. Let be the component in the x-direction in the Cartesian coordinate system. Let be the component in the y-direction in the Cartesian coordinate system. Let be the component in the Z direction in the Cartesian coordinate system, and .

5. The design method for a microchannel heat exchanger with freely growing fins according to claim 4, characterized in that, The centers of each cross-section are represented as follows: ； in, Indicates the first rib The center of the cross-section, This refers to the length of the rib.

6. The design method for a microchannel heat exchanger with freely growing fins according to claim 1, characterized in that, The convection-heat transfer analysis model and optimization model are expressed as follows: ； in, Indicates the first The first rib in the rib One control point, Indicates the first The first rib in the rib The normal vector of each cross section, Indicates the first The center point of each rib Indicates the first The preset discrimination coefficient of each rib, Represents the parameter set The microchannel pressure drop below Represents the parameter set Average temperature of the bottom surface of the microchannel. Design area for control points The design region for the normal vector. The design area for the origin point. The boundary conditions are as follows. This represents the governing equation.

7. The design method for a microchannel heat exchanger with freely growing fins according to claim 1, characterized in that, The optimal parameter set is obtained by iteratively solving the convection-heat transfer analysis model and the optimization model using the Grey Wolf optimization algorithm, including: Initialize the gray wolf population for the gray wolf optimization algorithm, and set each gray wolf individual in the gray wolf population as a set of parameters for the convection-heat transfer analysis model and the optimization model; Calculate the fitness value for each individual gray wolf; Perform non-dominated sorting based on the fitness value of each individual gray wolf, and select at least one leader wolf for the current iteration from the sorted gray wolf individuals according to the Pareto front, and update the positions of the remaining gray wolf individuals. When the preset number of iterations is reached, output at least one leader wolf in the Pareto front of the current iteration round as the optimal parameter set.

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