Novel pin-fin radiator based on functional gradient design strategy and design method thereof

Abstract

The invention belongs to the technical field of heat exchange, and provides a pin-fin radiator based on a functional gradient design strategy and a design method thereof, the radiator is composed of an upper heated wall surface, a lower heated wall surface and a pin-fin column, and cold fluid flows in from a left inlet, exchanges heat with a solid wall surface in a channel, flows out from a right outlet and takes away heat. The design method comprises the following steps: determining heat source temperature distribution; the temperature uniformity control is realized based on the functional gradient arrangement of the pin-fin heat dissipation columns; wherein the number and the diameter of the pin-fin columns in the fixed space are changed through functional gradient arrangement. According to the pin-fin type radiator designed based on the functional gradient design strategy, under the condition that the overall porosity is kept constant, more solids are arranged in an area with the large heat exchange intensity, the convection heat exchange intensity is improved, the pin-fin type radiator has the advantages of being compact in structure, excellent in heat exchange performance and the like, and the heat exchange effect is enhanced.

Description

Technical Field

[0001] This invention belongs to the field of heat exchange technology and relates to a novel pin-fin heat sink based on a functional gradient design strategy and its design method. Background Technology

[0002] With the increasing integration and miniaturization of electronic devices, the requirements for the compactness of heat dissipation structures are constantly rising. Furthermore, the uneven temperature distribution within the battery pack of electronic devices is becoming increasingly prominent, becoming a key factor affecting battery lifespan. Experiments on a 10-series, 10-parallel battery pack revealed a temperature concentration phenomenon in the battery heat sink, with higher temperatures in the central area and lower temperatures around the edges. This uneven temperature distribution affects the chemical reaction rate in each battery cell, thus impacting battery lifespan. Battery lifespan varies at different temperatures; the degradation rate doubles for every 10°C increase in temperature. Against this backdrop, controlling the temperature distribution of the battery pack and finding an efficient and compact heat dissipation structure is crucial for improving the performance of the thermal management system for electric vehicle battery packs. The primary site of heat exchange is the radiator, which, based on its internal structure, can be categorized into parallel fin radiators, foam metal structure radiators, and needle-fin radiators, etc. This invention primarily focuses on needle-fin radiators.

[0003] Needle-fin radiators enhance heat transfer by adding needle-like fins to a substrate. These fins, typically made of highly thermally conductive materials, not only increase the radiator's specific surface area but also enhance convective heat transfer by disturbing the fluid flowing over their surface. Compared to traditional parallel-fin radiators, needle-fin radiators offer higher heat dissipation efficiency and lower flow resistance. This is because the fins of needle-fin radiators can more effectively disturb the fluid, creating vortices and enhancing heat exchange between the fluid and the internal solid surface. In emerging research, topology optimization of heat dissipation structures is attracting significant attention, with applications in various fields such as electronic device radiators, heat exchangers, and thermal protection systems for aerospace vehicles. This approach allows for the design of highly efficient heat dissipation structures with complex geometries, often difficult to achieve using traditional design methods. Functional gradient design (FJD) is a promising strategy, seeking the optimal structural distribution within a given design space to meet specific heat transfer requirements. This method maintains a constant total porosity within the system's fins, transferring solids from saturated heat transfer regions to regions with lower heat transfer intensity, thereby improving the overall heat transfer efficiency of the system. Summary of the Invention

[0004] To address the problem of uneven temperature distribution in power batteries, electronic devices, heat exchangers, aerospace engines, and other similar devices, this invention proposes to improve the temperature uniformity of these devices and effectively enhance heat exchange efficiency by optimizing the internal structure of the radiator channels using functional gradient design.

[0005] This invention provides the following technical solution:

[0006] This invention provides a design method for a novel pin-fin radiator based on functional gradient, which improves temperature control and uniformity in the heat source area, including the following steps:

[0007] S1: Determine the temperature distribution of the heat source and the target temperature uniformity of the radiator;

[0008] S2: Design the heat sink based on step S1, and select the function gradient function. Determine the number of needle-wing columns;

[0009] S3: Design the heat sink based on step S1, and select the function gradient function. Determine the diameter of the needle-wing column;

[0010] S4: Select a metal or alloy with appropriate thermal conductivity according to the application scenario, and use laser melting process to manufacture the heat sink.

[0011] Furthermore, the functional gradient function is determined based on the temperature distribution and size of the heat source, and then the functional gradient function controls the number and diameter of the pin fins in the radiator, specifically including:

[0012] The temperature distribution and major axis length of the heat source make L in the function of functional gradient equal to the major axis length of the heat source;

[0013] After selecting L, the number and diameter of the needle-wing columns are calculated based on the functional gradient functions f(L)1 and f(L)2;

[0014] Construct a radiator based on the known number and diameter of the needle-fin columns.

[0015] Furthermore, according to step S2, there is a functional relationship between the size of the heat source and the number of needle-fin columns. in:

[0016] Furthermore, according to step S3, there is a functional relationship between the size of the heat source and the diameter of the needle-fin column.

[0017] And: Substituting the functions f(m) and f(n), we obtain the functional gradient functions f(L)1 and f(L)2:

[0018]

[0019] In the formula, m is the functional gradient factor 1, representing the number of pin-fin columns inside the heat sink; n is the functional gradient factor 2, representing the diameter of the pin-fin columns within the internal channel unit structure of the heat sink. f(m) represents the equation for the solidity of the internal structure of the system under the influence of functional gradient factor m; f(n) represents the equation for the solidity of the internal structure of the system under the influence of functional gradient factors m and n; k in f(L)1 is a selected value, with the optimal value being k = 400; d represents the diameter of each pin-fin column, in meters. j in f(L)2 is a selected value, with the optimal value being j = 1; d i-1 =d m-1 To be taken as a fixed value, representing the diameter of the needle-fin column within each unit length, in meters; x i Here, k and j represent the x-coordinate of the first fin within different unit structures; W represents the width of the radiator system channel; H represents the height of the radiator system channel; and L represents the length of the radiator system channel. Since k and j are selected values, when the length L of the radiator changes, the most suitable m and n can always be found, which is the optimal distribution strategy of the needle-fin column inside the radiator. If the value of L is selected, only the values ​​of k and j need to be changed, and the optimal radiator structure can be found by comparing the heat dissipation effects.

[0020] Furthermore, the radiator includes an upper wall, a lower wall, and needle-fin columns within different unit structures; the upper and lower walls can be circular, teardrop-shaped, rectangular, star-shaped, or other similar geometric shapes; the cross-section of the needle-fin columns can be circular, rectangular, hexagonal, or other similar geometric shapes; the distribution of the needle-fin columns in the internal channels follows a functional gradient function, distributed between the upper and lower walls, and forming vertical columns with an angle of 10°-90° with the upper and lower walls.

[0021] The porosity of the radiator can be selected between 0.5 and 0.9. Within this range, the lower the porosity, the higher the heat dissipation of the radiator. A porosity below 0.5 will result in excessively large pin fin diameters, causing them to overlap. A porosity above 0.9 will result in excessively small pin fin diameters, leading to insufficient mechanical properties of the radiator, such as compressive strength.

[0022] Furthermore, along the fluid flow direction, the remaining length of the internal fluid channel is divided into m unit lengths along the long axis L; within each unit length, needle-fin columns are distributed along the width W direction, with a height consistent with the height of the fluid channel.

[0023] Furthermore, the fluid flows parallel to the upper and lower walls within the system's internal structure; furthermore, the upper and lower walls of the system serve as heat sources, with temperatures ranging from 323.15K to 373.15K, transferring heat to the interior of the needle-fin column through conduction; the lower-temperature fluid flows in from the inlet, carrying away the heat from the needle-fin column through convection, and finally flows out from the outlet, thus completing heat exchange between the low-temperature fluid and the high-temperature needle-fin column.

[0024] The present invention also provides a needle-fin radiator prepared by the above design method.

[0025] Furthermore, the heat sink material is a high thermal conductivity material such as an alloy, including aluminum alloy, copper alloy, or a low thermal conductivity material; wherein the needle-fin type functional gradient structure is manufactured by laser melting (SLM) or metal stamping.

[0026] The beneficial effects of this invention are as follows:

[0027] A functionally graded pin-fin heat sink and its design method are disclosed, which have advantages such as compact structure, reasonable heat transfer area distribution, and high heat exchange efficiency. In particular, the independently designed functional gradient function allows for the placement of more heat-transferring solids in areas of high heat transfer intensity while maintaining constant porosity, thereby enhancing convective heat transfer intensity and improving the temperature uniformity of heated objects. This invention provides a new approach and design method for solving the problem of uneven temperature distribution in heat sinks, heat exchangers, and battery packs inside aerospace vehicles. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A flowchart illustrating the design methodology for a functionally graded pin-fin radiator.

[0030] Figure 2 Top view of the internal structure of a functionally graded needle-fin radiator (m=10, n=0.025);

[0031] Figure 3 This is a streamline diagram of the internal structure of a functionally graded pin fin radiator.

[0032] Figure 4 Side view of a functionally graded pin-fin radiator;

[0033] Figure 5This is a front view of a functionally graded pin-fin radiator.

[0034] Figure 6 This is a temperature distribution diagram for a functionally graded pin-fin radiator. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] See Figure 1 This invention provides a design method for a novel pin-fin radiator based on functional gradient, which improves temperature control and uniformity in the heat source area, including the following steps:

[0037] S1: Determine the temperature distribution of the heat source and the target temperature uniformity of the radiator;

[0038] S2: Design the heat sink based on step S1, and select the function gradient function. Determine the number of needle-wing columns;

[0039] S3: Design the heat sink based on step S1, and select the function gradient function. Determine the diameter of the needle-wing column;

[0040] S4: Select a metal or alloy with appropriate thermal conductivity according to the application scenario, and use laser melting process to manufacture the heat sink.

[0041] by Figures 2 to 6 Taking the operating condition shown as an example, the length of the internal fluid channel L = 2.5 × 10 -2 m, width W = 2.5 × 10 - 3 m, height H=5×10 -3 m, at this time the ratio of the length to the height of the internal fluid channel is 5, and the ratio of the width to the height of the internal fluid channel is 0.5; from k=400, j=1, the optimal distribution of the needle-fin columns of the internal channel can be obtained, which are m=10 and n=0.025 respectively.

[0042] There exist m = kL, n = jL; values ​​are selected where k = 400, k = 1, and L = 2.5 × 10⁻⁶. -2 m, W = 2.5 × 10 -3 m, H = 5 × 10 -3 m; d = 1 × 10 -3 m,d m =1.3×10 -4Taking m; ε = 0.875 as an example, that is, m = 10 and n = 0.025, the experimental results of the embodiment and the comparative example are analyzed and compared.

[0043] Example 1.

[0044] like Figure 1 As shown, in this invention, a functionally graded pin-fin radiator and its design method are constructed from pin-fin columns, an upper wall (1), and a lower wall. Within the unit structure (2), there are three pin-fin columns, each with a diameter of d2; and so on. Each radiator is composed of countless unit structures arranged horizontally and vertically, with a length of l. m The cross-section of the needle-fin column is circular. Under the influence of different functional gradient functions, while keeping the overall porosity of the internal structure of the system constant, the diameter of the needle-fin column inside each unit structure is the same; the diameter of the needle-fin column inside different unit structures varies along the x-axis according to the function law; the height of each needle-fin column is the same as the height of the fluid channel. The upper wall (1) and the lower wall are rectangular with low thickness and coated with thermal grease, which has good thermal conductivity and can better introduce the external temperature into the structure, thereby improving the heat dissipation efficiency.

[0045] The inlet receives cold air (air from the atmospheric environment) flowing in, and... Figure 1 , Figure 2 It can be seen that the fluid flows in the direction of (5), from the inlet to the outlet; it carries away heat during the flow process to improve heat dissipation efficiency.

[0046] The function gradient function is:

[0047]

[0048] The overall porosity is 0.5-0.9.

[0049] The height of the needle-fin column within the fluid channel is 5mm; for example Figure 1 As shown, under the influence of parameter k, the diameters of the needle-fin columns inside the system are the same, and the length l of each unit structure is... m Unlike other systems, under the premise of keeping the internal porosity constant, as the number of unit structures m increases, the diameter of the needle-wing columns inside the system changes regularly according to the functional gradient function 1; under the action of parameter j, the number of unit structures is constant, and the diameter of the needle-wing columns inside each unit structure is the same. Under the premise of keeping the internal porosity constant, along the x-axis, the diameter of the needle-wing columns inside different unit structures changes regularly according to the functional gradient function 2.

[0050] Selected values: k = 400, j = 1, i.e., m = 10, n = 0.025, such as... Figure 3As shown, 10 unit structures are selected along the x-axis and arranged at equal intervals. The number of units in each row is equal to the number of unit structures, for a total of 3 rows and 30 needle-wing columns.

[0051] like Figure 5 As shown in the temperature distribution diagram, during the heat exchange process, the upper end of the needle-fin column is connected to the upper wall (1), and the lower end is connected to the lower wall. The overall height is equal to the height of the fluid channel. The upper and lower walls are the source of heat, and the fluid is low-temperature air. The low-temperature air flows into the system from the inlet and flows in a laminar manner in the unit structure (2). The needle-fin columns (3) and (4) inside the unit structure exchange heat with the upper wall (1) and the lower wall. The temperature of the upper and lower walls is introduced into the system through heat conduction. When the low-temperature air flows in the system, it exchanges heat with the needle-fin column and carries away the heat on the needle-fin column by convection. At the same time, the streamline (5) angle of the low-temperature air changes slightly. Finally, the low-temperature air flows out of the radiator from the outlet.

[0052] For the sake of compactness, the structures of the embodiments and comparative examples are of equal quality, with a porosity of 0.875.

[0053] The temperature of the upper and lower walls was selected to be 353.15K, and the temperature of the low-temperature air was 293.15K. During the flow of the low-temperature air, its flow mode, inlet velocity, and outlet pressure boundary conditions were not changed. Furthermore, network independence was verified for the embodiments and comparative examples, and the heat dissipation of the embodiments and comparative examples was analyzed and compared.

[0054] Comparative Example 1

[0055] Based on Example 1, the following parameters were selected: k = 400, j = 2, i.e., m = 10, n = 0.05, and the number of unit structures along the x-axis was 10. The diameter of the internal needle-fin column was calculated and selected by f(L)2. Experiments were conducted on the functionally graded needle-fin heat sink with the selected parameters: k = 400, j = 2, and the heat dissipation performance of the structure was compared and analyzed.

[0056] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 was higher than that of Comparative Example 1. L It is 1.12% higher.

[0057] Comparative Example 2

[0058] Based on Example 1, the following parameters were selected: k = 400, j = 3, i.e., m = 10, n = 0.075, and the number of unit structures along the x-axis was 10. The diameter of the internal pin-fin column was calculated and selected by f(L)2. Experiments were conducted on the functionally graded pin-fin heat sink with the selected parameters: k = 400, j = 3, and the heat dissipation performance of the structure was compared and analyzed.

[0059] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 compared to Comparative Example 2 was higher. L It is 1.31% higher.

[0060] Comparative Example 3

[0061] Based on Example 1, the following parameters were selected: k = 400, j = 4, i.e., m = 10, n = 0.1. The number of unit structures along the x-axis was 10, and the diameter of the internal pin-fin columns was calculated and selected by f(L)2. Experiments were conducted on the functionally graded pin-fin heat sink with the selected parameters: k = 400, j = 4, and the heat dissipation performance of the structure was compared and analyzed.

[0062] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 compared to Comparative Example 3 was higher. L It is 2.79% higher.

[0063] Comparative Example 4

[0064] Based on Example 1, the following parameters were selected: k = 400, j = 0, i.e., m = 10, n = 0. The number of unit structures along the x-axis was 10, and the diameter of the internal needle-fin column was calculated and selected by f(L)2. Experiments were conducted on the functionally graded needle-fin heat sink with the selected parameters: k = 400, j = 0, and the heat dissipation performance of the structure was compared and analyzed.

[0065] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 compared to Comparative Example 4 was higher. L It is 1.96% higher.

[0066] Comparative Examples 1 to 4 above show that the functional gradient functions f(L)1 and f(L)2 calculated with k=400 and j=1 achieve the best heat dissipation effect. Increasing or decreasing j on this basis will lead to a decrease in heat dissipation effect.

[0067] Comparative Example 5

[0068] Based on Example 1, the parameters in f(L)1 of Example 1 were changed to affect the calculated number of pin fin columns. The parameters selected were: k = 200, j = 0, i.e., m = 5, n = 0, with 5 unit structures along the x-axis. Since j = 0, it indicates that the diameters of the pin fin columns within different unit structures are equal. Experiments were conducted on the functionally graded pin fin radiator with the selected parameters: k = 200, j = 0, to compare and analyze the heat dissipation performance of the two structures.

[0069] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 compared to Comparative Example 5 was higher. L It is 14.35% higher.

[0070] Comparative Example 6

[0071] Based on Example 1, the parameters in f(L)1 of Example 1 were changed to affect the calculated number of pin fin columns. The parameters selected were: k = 320, j = 0, i.e., m = 8, n = 0, with 8 unit structures along the x-axis. Since j = 0, it indicates that the diameters of the pin fin columns within different unit structures are equal. Experiments were conducted on the functionally graded pin fin heat sink with the selected parameters: k = 320, j = 0, to compare and analyze the heat dissipation performance of the two structures.

[0072] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 compared to Comparative Example 6 was higher. L It is 2.34% higher.

[0073] Comparative Example 7

[0074] Based on Example 1, the parameters in f(L)1 of Example 1 were changed to affect the calculated number of pin fin columns. The parameters selected were: k = 480, j = 0, i.e., m = 12, n = 0, with 12 unit structures along the x-axis. Since j = 0, it indicates that the diameters of the pin fin columns within different unit structures are equal. Experiments were conducted on the functionally graded pin fin heat sink with the selected parameters: k = 480, j = 0, to compare and analyze the heat dissipation performance of the two structures.

[0075] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 compared to Comparative Example 7 was higher. L It is 3.61% higher.

[0076] Comparative Example 8

[0077] Based on Example 1, the parameters in f(L)1 of Example 1 were changed to affect the calculated number of pin fin columns. The parameters selected were: k = 640, j = 0, i.e., m = 16, n = 0, with 16 unit structures along the x-axis. Since j = 0, it indicates that the diameters of the pin fin columns within different unit structures are equal. Experiments were conducted on the functionally graded pin fin heat sink with the selected parameters: k = 640, j = 0, to compare and analyze the heat dissipation performance of the two structures.

[0078] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 compared to Comparative Example 8 was higher. L It is 5.23% higher.

[0079] Comparative Examples 5 to 8 above show that the functional gradient functions f(L)1 and f(L)2 calculated with k=400 and j=1 achieve the best heat dissipation effect. Increasing or decreasing k on this basis will lead to a decrease in heat dissipation effect.

[0080] Comparative Example 9

[0081] Based on Example 1, the internal structure of Example 1 was completely replaced with a traditional finned structure. The heat dissipation of the two structures was compared and analyzed.

[0082] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 compared to Comparative Example 9 was higher. L It is 15.68% higher.

[0083] Comparative Example 10

[0084] Based on Example 1, the internal structure of Example 1 was completely replaced with a Vertical pin fin structure. The heat dissipation of the two structures was compared and analyzed.

[0085] The comparison results showed that the Nusselt number (Nu) characterizing the heat transfer performance of Example 1 compared to Comparative Example 10 was higher. L It is 16.10% higher.

[0086] The comparison results of the heat dissipation performance of the above embodiments and comparative examples are shown in Table 1:

[0087] Table 1 Comparison of heat dissipation performance between the embodiments of the present invention and the comparative examples

[0088]

[0089] In applications such as heat sinks, heat exchangers, and battery packs inside aerospace vehicles, the fluid is generally atmospheric air. This invention significantly increases the heat exchange area and improves heat dissipation efficiency, providing a new approach to solving the problem of uneven temperature distribution in battery packs.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method of a new pin-fin heat sink based on functional gradient to improve temperature control and uniformity in the heat source region, characterized by, The method comprises the following steps: S1: determining the temperature distribution of the heat source and determining the uniform temperature target of the heat sink; S2: design the heat sink according to step S1, select a function gradient function determining the number of pin fins; S3: design the heat sink according to step S1, select a function gradient function determine the diameter of the pin fin S4: selecting a metal or alloy with a suitable thermal conductivity according to the use scenario, and selecting a laser melting process to manufacture the heat sink.

2. The design method of a novel pin-fin heat sink based on functionally graded, as claimed in claim 1, wherein: The heat sink comprises an upper wall surface, a lower wall surface, and needle fin columns; the needle fin columns are located between the upper and lower wall surfaces, and the distribution of the internal channels follows a functionally graded design strategy; the values of k and j in the functionally graded functions f(L)1 and f(L)2 are determined according to the size and use scenario of the heat source to control the distribution of the needle fin columns in the internal channels of the heat sink; L is the length of the internal channels of the heat sink.

3. The design method of a novel pin-fin heat sink based on functionally graded, as claimed in claim 1, wherein: The functionally graded function is determined according to the temperature distribution and size of the heat source, and the number and diameter of the needle fin columns in the heat sink are controlled by the functionally graded function, which specifically comprises: The temperature distribution and major axis length of the heat source are used to make L in the functionally graded function equal to the major axis length of the heat source; After L is selected, the number and diameter of the needle fin columns are calculated according to the functionally graded functions f(L)1 and f(L)2; The heat sink is constructed according to the known number and diameter of the needle fin columns.

4. The design method of a novel pin-fin heat sink based on functionally graded, as claimed in claim 1, wherein: The temperature distribution of the heat source is determined, a plurality of sampling points are selected on the heat source, the temperature of each observation point is observed without the addition of a heat sink, and a temperature distribution cloud map of the heat source is constructed according to the temperatures of the plurality of sampling points.

5. The design method of a novel pin-fin heat sink based on functionally graded, as claimed in claim 1, wherein: The number of internal unit structures of the functionally graded heat sink is m, the diameter index of the needle fin columns in different internal unit structures is n, there are m=kL and n=jL, and the porosity of the heat sink structure is 0.5-0.

9.

6. The design method of a novel pin-fin heat sink based on functionally graded, as claimed in claim 1, wherein: The shapes of the upper wall surface and the lower wall surface of the heat sink are related to the application scenario, and include a circular shape, a water drop shape, a rectangular shape, a star shape, or other similar geometric shapes.

7. The design method of a novel pin-fin heat sink based on functionally graded, as claimed in claim 1, wherein: The cross section of the needle fin column is related to the application scenario, and includes a circular shape, a rectangular shape, a hexagonal shape, or other similar geometric shapes.

8. The design method of novel pin-fin heat sink based on functionally graded, as claimed in claim 7, wherein: The needle fin column is a vertical column with an included angle of 90°, an inclined column with an included angle less than 90° with the upper wall surface, or a column deformed by bending.

9. A needle fin type heat sink designed by the design method in any of claims 1-8.

10. The pin-fin heat sink of claim 9, wherein, The material of the heat sink is a high thermal conductivity material such as an alloy, including an aluminum alloy, a copper alloy, or a low thermal conductivity material; the needle fin type functionally graded structure is manufactured by a laser melting process or a metal stamping method.

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