Fractal tree-shaped micro-channel rectangular heat sink and design method

Abstract

The invention discloses a fractal tree-shaped micro-channel rectangular heat sink and a design method, and is applied to the technical field of heat and mass transfer, and the structure parameters of the fractal tree-shaped micro-channel rectangular heat sink comprise the number of inlet section channels, the bifurcation level, the length of an inlet flow channel, the width of the inlet flow channel, a length scaling factor and a width scaling factor; the inlet section channel number and the bifurcation level are used for determining the topological structure of the fractal tree-shaped micro-channel; the length and the width of the inlet runner are used for determining the size of the rectangular heat sink inlet; the length proportion scaling factor and the width proportion scaling factor are used for calculating the length proportion and the width proportion of each branch flow channel; through the Y-shaped fractal tree-shaped micro-channel rectangular heat sink of the space filling network, on the basis of fully utilizing the heat transfer space, the flow resistance loss is reduced, and meanwhile, the limitation of a traditional circular substrate heat sink in rectangular heat load equipment cooling is solved.

Description

Technical Field

[0001] This invention relates to the field of heat and mass transfer technology, and in particular to a fractal tree-shaped microchannel rectangular heat sink and its design method. Background Technology

[0002] In recent years, inspired by biological systems with excellent transport properties in nature, such as plant branches and animal blood vessels, fractal tree-like microchannel heat sinks have been gradually applied to various heat exchange systems due to their high heat dissipation and low pressure drop characteristics. When fractal structures from nature are applied to practical heat dissipation systems, the heat sink substrate is mainly either circular or rectangular, depending on the shape of the heat load. In practical applications of cooling rectangular heat load equipment, the circular substrate design is subject to many limitations, such as radiator installation and incompatibility with the heat load equipment; while the flow channel topology of rectangular heat sinks still has considerable room for optimization.

[0003] Fractal characteristics are exhibited in various transport systems in nature, such as transport systems within organisms, topography, and water networks. The formation and existence of these fractal structures are not accidental, but driven by universally existing physical and biological principles. This fractal characteristic, resembling a natural law, can actually be viewed as an optimization strategy; by maintaining self-similarity at different scales, the system can effectively minimize energy loss. This superior transport property has led to the widespread application of this structure in engineering. However, in order to design fractal tree-like microchannel heat sinks that meet engineering application requirements, existing fractal tree-like microchannels have only achieved minimum flow resistance and cannot guarantee maximum heat transfer simultaneously.

[0004] To overcome these shortcomings, this application proposes a fractal tree-like microchannel rectangular heat sink and its design method. Summary of the Invention

[0005] The purpose of this application is to provide a fractal tree-shaped microchannel rectangular heat sink and its design method, which aims to solve the problem of efficient heat transfer in fractal tree-shaped microchannel rectangular heat sinks.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] In a first aspect, this application provides a fractal tree-shaped microchannel rectangular heat sink, wherein the structural parameters of the fractal tree-shaped microchannel rectangular heat sink include: the number of channels in the inlet cross section, the bifurcation level, the length of the inlet channel, the width of the inlet channel, the length scaling factor, and the width scaling factor;

[0008] The number of channels at the inlet cross section and the bifurcation level are used to determine the topology of the fractal tree-like microchannels;

[0009] The length and width of the inlet channel are used to determine the dimensions of the rectangular heat sink inlet;

[0010] The length scaling factor and the width scaling factor are used to calculate the length and width ratios of each level of the branching flow channel.

[0011] Secondly, this application provides a fractal tree-like microchannel rectangular heat sink design method, comprising:

[0012] Obtain the design objectives and geometric constraints of the rectangular heat sink;

[0013] Based on the design objectives and geometric constraints, the structural parameters of the rectangular heat sink are obtained;

[0014] The optimal structural parameters were solved using a multi-objective optimization algorithm, resulting in the designed fractal tree-shaped microchannel rectangular heat sink.

[0015] This application provides a fractal tree-shaped microchannel rectangular heat sink and its design method, which has the following beneficial effects:

[0016] (1) By using the structural parameters of the heat sink, including the number of channels in the inlet section, the bifurcation level, the length and width of the inlet channel, the length scaling factor and the width scaling factor, this application achieves fine control over the topology and size of the fractal tree microchannel; under the combined effect of these structural parameters, the “Y”-shaped fractal tree microchannel is laid out on the rectangular heat sink in the form of a space-filling network, thereby making full use of the heat sink area and increasing the heat exchange capacity of the heat sink;

[0017] (2) This application proposes a design method for a rectangular heat sink with fractal tree-shaped microchannels. By using the structural parameters and layout of the fractal tree-shaped microchannels, the heat transfer efficiency of the heat sink is significantly improved, so that heat can be transferred from the heat source to the cooling medium more quickly and effectively. At the same time, this design method is not only applicable to rectangular heat sinks, but can also be further extended to the design of heat sinks of other shapes and sizes, so as to achieve maximum heat transfer with minimum energy consumption. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a fractal tree-like microchannel rectangular heat sink structure according to Embodiment 1 of this application;

[0019] Figure 2 This is a flowchart illustrating a fractal tree-shaped microchannel rectangular heat sink design method according to Embodiment 2 of this application. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0021] The following analysis, based on relevant technologies, examines existing solutions.

[0022] There are two main types of existing fractal tree-shaped microchannel rectangular heat sink substrates: (1) using a "Y"-shaped bifurcation structure as the fractal unit, based on Murray's law of minimum flow resistance or maximum heat transfer efficiency, the fractal network is arranged on the rectangular heat sink in a non-space-filling manner; (2) using a "T"-shaped bifurcation structure as the fractal unit, based on Murray's law of minimum flow resistance or maximum heat transfer efficiency, the fractal network is arranged on the rectangular heat sink in a non-space-filling manner.

[0023] There is room for further optimization in the existing two fractal tree-like microchannel rectangular heat sink flow channel layout methods. For the layout using a "Y"-shaped bifurcation structure as the fractal unit, the scale factor constraint of Murray's law results in a non-space-filling layout on the rectangular heat sink. This means that the heat transfer area of ​​the heat sink is underutilized, leading to a smaller designed heat dissipation capacity. For the layout using a "T"-shaped bifurcation structure as the fractal unit, although this method uses a space-filling network layout, the right-angle bifurcation increases the pressure loss before and after the bifurcation, resulting in significant heat dissipation energy loss.

[0024] This application lays out a Y-shaped fractal tree-like microchannel in the form of a space-filling network on a rectangular heat sink, which can make full use of the heat sink area, increase the heat exchange capacity of the heat sink, and reduce the consumption of flow resistance.

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] Example 1

[0027] Please see Figure 1 This is a schematic diagram of a fractal tree-like microchannel rectangular heat sink structure according to Embodiment 1 of this application; specifically, it is a schematic diagram of a three-branched fractal tree-like microchannel heat sink (FTMC-B3) structure. The rectangular heat sink has a length L... h 100mm, width W h 60mm, height H h It is 4mm. This structure has N FT =Eight fractal tree-like microchannels are symmetrically distributed on a rectangular heat sink; the channel height is 3mm, and the branching level B of each fractal tree-like microchannel is 3. This can be understood as the number of channels N at the inlet cross-section. FTBy taking different values ​​for the branching level B, fractal tree network designs with different branching levels can be achieved.

[0028] The structural parameters of the fractal tree-shaped microchannel rectangular heat sink include: the number of channels in the inlet section, the bifurcation level, the length of the inlet channel, the width of the inlet channel, the length scaling factor, and the width scaling factor.

[0029] The number of channels at the inlet cross section and the bifurcation level are used to determine the topology of the fractal tree-like microchannels;

[0030] The length and width of the inlet channel are used to determine the dimensions of the rectangular heat sink inlet;

[0031] The length scaling factor and the width scaling factor are used to calculate the length and width ratios of each level of the branching flow channel.

[0032] In one embodiment, a Y-shaped fractal tree-like microchannel is deployed on a rectangular heat sink in the form of a space-filling network. The structural design parameters of the heat sink include: the number of channels N at the inlet cross-section. FT Bifurcation level B, inlet channel length L FT,i Width W of the inlet channel FT,1 Length scaling factor D L and width scaling factor D W .

[0033] Number of inlet cross-section channels N FT The bifurcation level B determines the topology of the fractal tree-like microchannels. With consistent inlet channel dimensions, a higher number of channels at the inlet cross-section results in a larger heat transfer area; conversely, a higher bifurcation level results in a smaller maximum number of channels at the inlet cross-section. Given a specific number of channels at the inlet cross-section and a bifurcation level, the length and width of the inlet channel, along with the scaling factor for length and width, determine the specific dimensions of each channel level, significantly impacting the overall heat transfer and flow characteristics.

[0034] Specifically, the fractal tree-like microchannels at the branching level are defined as straight rectangular flow channels, symmetrically arranged within the rectangular heat sink. The dimensions of the straight rectangular flow channels are determined based on the self-similarity characteristics of the fractal tree structure, expressed by the formula:

[0035]

[0036]

[0037] Where i represents the i-th level branch, with values ​​of 1, 2, ..., B; L i and W iα and β are the length and width of the i-th level bifurcation channel, respectively; β and γ are the length ratio and width ratio of each level bifurcation channel, respectively.

[0038] The formulas for calculating the length ratio β and width ratio γ of each level of branching flow channel are as follows:

[0039]

[0040]

[0041] Among them, D L and D W These are the length scaling factor and the width scaling factor, respectively.

[0042] Furthermore, based on the structural parameters of the fractal tree-shaped microchannel rectangular heat sink, the following geometric constraints are satisfied within the preset rectangular design domain:

[0043]

[0044] Among them, L h B is the length of the rectangular base; B is the bifurcation level; i is the i-th bifurcation level; L FT,i N is the length of the inlet channel; FT W represents the number of channels at the inlet cross-section. FT,1 W is the width of the inlet channel. s,1 W is the rib width between the first-level bifurcation flow channels. h W is the width of the rectangular base. FT,B W represents the width of the fractal tree-like microchannel outlet. s,B L is the rib width between the B-level bifurcation channels; r,i C0 and C1 represent the length of the i-th branch level flow channel projected along the length direction; C0 and C1 represent the design accuracy.

[0045] In the geometric constraints, the first constraint states that the total length of the fractal tree-like microchannel is greater than the length of the rectangular heat sink; the second constraint states that the width of the fractal tree-like microchannel at the inlet does not exceed the width of the rectangular heat sink; the third constraint states that the total width of the fractal tree-like microchannel at the outlet does not exceed the width of the rectangular heat sink; the fourth constraint states the design accuracy; and the fifth constraint states the machining accuracy.

[0046] In summary, Embodiment 1 of this application proposes to arrange a "Y"-shaped fractal tree-like microchannel in the form of a space-filling network onto a rectangular heat sink. The design parameters of this rectangular heat sink include structural parameters such as the number of channels in the inlet cross-section, the branching level, the length of the inlet channel, the width of the inlet channel, the length scaling factor, and the width scaling factor. These structural parameters collectively determine the topology and specific dimensions of the fractal tree-like microchannel. This design significantly improves the overall heat transfer performance of the heat sink, fully utilizing the heat sink area to increase heat exchange while reducing flow resistance losses, and has great application potential.

[0047] Example 2

[0048] Please see Figure 2 This is a flowchart illustrating a design method for a fractal tree-shaped microchannel rectangular heat sink according to Embodiment 2 of this application; the specific steps include:

[0049] Obtain the design objectives and geometric constraints of the rectangular heat sink;

[0050] Based on the design objectives and geometric constraints, the structural parameters of the rectangular heat sink are obtained;

[0051] The optimal structural parameters were solved using a multi-objective optimization algorithm, resulting in the designed fractal tree-shaped microchannel rectangular heat sink.

[0052] In this embodiment, the structural parameters include: number of inlet cross-section channels, bifurcation level, length of inlet channel, width of inlet channel, length scaling factor, and width scaling factor.

[0053] In multi-objective optimization algorithms, the objectives are to minimize heat transfer resistance and pump power. The optimal structural parameters are calculated under different heat dissipation requirements, thus optimizing the heat and mass transfer processes. The specific formula is as follows:

[0054] F(x)=min(P pumping (x),R tot (x))

[0055]

[0056] Among them, P pumping R is the pump power. tot For heat transfer, the thermal resistance is denoted by g, and both are determined by the prediction model for the corresponding operating conditions; x represents the structural parameter; g represents the thermal resistance. j These are the geometric constraints for the fractal tree structure.

[0057] In one embodiment, taking a heat dissipation requirement, i.e., a thermal resistance of 0.35 K / W, as an example, the optimal number of inlet cross-section channels, the optimal length of the inlet channel, the optimal width of the inlet channel, the optimal length scaling factor, and the optimal width scaling factor are 9, 56.01 mm, 2.82 mm, 3.86, and 1.14, respectively. The pump power required to achieve heat dissipation is 0.56 mW.

[0058] In summary, the fractal tree-shaped microchannel rectangular heat sink design method proposed in this embodiment 2 obtains the optimal structural parameters, solves the problem of local optima in flow heat transfer performance caused by existing single-objective optimization, and achieves maximum heat transfer with minimum energy consumption.

[0059] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0060] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural changes made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

[0061] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

[0062] Of course, the present invention may have many other embodiments. Based on this embodiment, other embodiments obtained by those skilled in the art without any creative effort are all within the scope of protection of the present invention.

Claims

1. A fractal tree microchannel rectangular heat sink, characterized by, The structural parameters of the fractal tree-shaped microchannel rectangular heat sink include: the number of channels in the inlet cross section, the bifurcation level, the length of the inlet flow channel, the width of the inlet flow channel, the length scaling factor and the width scaling factor. The number of channels in the inlet cross section and the bifurcation level are used to determine the topological structure of the fractal tree-shaped microchannel. The length of the inlet flow channel and the width of the inlet flow channel are used to determine the size of the rectangular heat sink inlet. The length scaling factor and the width scaling factor are used to calculate the length ratio and the width ratio of each level of bifurcation flow channel.

2. A fractal tree microchannel rectangular heat sink according to claim 1, wherein The fractal tree-shaped microchannel at the bifurcation level is defined as a straight rectangular flow channel, which is symmetrically arranged in the rectangular heat sink. The size of the straight rectangular flow channel is determined according to the self-similarity of the fractal tree-shaped structure, and the formula is expressed as: wherein i is the i-th bifurcation, i = 1, 2, …, B; L i and W i are the length and width of the i-th bifurcation channel, respectively; β and γ are the length ratio and width ratio of the bifurcation channels, respectively.

3. A fractal tree microchannel rectangular heat sink according to claim 2, wherein The calculation formula of the length ratio and the width ratio of each level of bifurcation flow channel is: where D L and D W are length and width scaling factors, respectively.

4. The fractal tree microchannel rectangular heat sink of claim 1, wherein, According to the structural parameters of the fractal tree-shaped microchannel rectangular heat sink, the following geometric constraint conditions are met in the preset rectangular design domain: wherein, L h is the length of the rectangular base; B is the bifurcation level; i is the i-th bifurcation level; L FT,i is the length of the inlet flow channel; N FT is the number of inlet cross-sectional channels; W FT,1 is the width of the inlet flow channel; W s,1 is the rib width between the first bifurcation level flow channels; W h is the rectangular base width; W FT,B is the fractal tree microchannel outlet width; W s,B is the rib width between the B-th bifurcation level flow channels; L r,i is the length of the i-th bifurcation level flow channel in the length direction projection; C0, C1 are design accuracy; The first constraint condition in the geometric constraint condition represents that the total length of the fractal tree-shaped microchannel is greater than the length of the rectangular heat sink; the second constraint condition represents that the width of the fractal tree-shaped microchannel at the inlet does not exceed the width of the rectangular heat sink; the second constraint condition represents that the width of the fractal tree-shaped microchannel at the outlet does not exceed the width of the rectangular heat sink; the fourth constraint condition represents the design accuracy; and the fifth constraint condition represents the machining accuracy.

5. The fractal tree microchannel rectangular heat sink of claim 1, wherein, The rectangular heat sink is arranged in the form of a space-filling network by "Y" type fractal tree-shaped microchannels.

6. A method of designing a fractal tree microchannel rectangular heat sink according to claim 1, wherein, It includes: Obtaining the design target and geometric constraint condition of the rectangular heat sink; According to the design target and the geometric constraint condition, the structural parameters of the rectangular heat sink are obtained; An optimal structural parameter is obtained by using a multi-objective optimization algorithm, and a designed fractal tree-shaped microchannel rectangular heat sink is obtained.

7. The method of designing a fractal tree microchannel rectangular heat sink of claim 6, wherein, The structural parameters include: the number of channels in the inlet cross section, the bifurcation level, the length of the inlet flow channel, the width of the inlet flow channel, the length scaling factor and the width scaling factor.

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