A method for optimizing parameters of a surface microchannel heat exchanger with curved topology microstructure

Abstract

This invention discloses a parameter optimization method for a surface microchannel heat exchanger with a curved topology microstructure, relating to the field of electronic chip heat dissipation. The method includes: determining the target design parameters of the surface microchannel heat exchanger with a curved topology microstructure; determining N factor levels for the coolant flow rate parameter; determining the factor levels for each structural parameter; conducting single-factor experiments based on the factor levels of each structural parameter to obtain the comprehensive heat transfer performance of each structural parameter at each factor level; selecting the N factor levels with the highest comprehensive heat transfer performance among all structural parameters; and conducting orthogonal experiments and range analysis based on the N factor levels with the highest comprehensive heat transfer performance and the N factor levels of the coolant flow rate parameter to obtain the optimal combination of the target design parameters. This invention results in an optimized heat exchanger with better heat transfer effect and lower flow resistance, and the highest comprehensive heat transfer performance.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation technology for electronic products, and in particular to a method for optimizing the parameters of a surface microchannel heat exchanger with a curved topology microstructure. Background Technology

[0002] As the integration of electronic chips continues to increase, the heat dissipation problem of electronic devices is becoming increasingly severe. Microchannel heat sinks, with their significant advantages of small size and high heat dissipation efficiency, have become a key technology for solving the heat dissipation problem of high power density devices. To further improve heat transfer performance, current research mainly focuses on adding conventional microstructures such as rectangles and cylinders to the surface of microchannels. While these microstructures increase the heat transfer effect of microchannels, they also generate higher flow resistance, leading to a corresponding increase in the pump power required for the microchannels. Summary of the Invention

[0003] To address the technical problems existing in the background art, this invention proposes a method for optimizing the parameters of a surface microchannel heat exchanger with a curved topology microstructure.

[0004] This invention proposes a method for optimizing the parameters of a surface microchannel heat exchanger with a curved topological microstructure, comprising:

[0005] Determine the target design parameters for the surface microchannel heat exchanger with curved topology microstructure; the target design parameters include structural parameters and coolant flow rate parameters, wherein the structural parameters include the length, width and height of the curved microstructure;

[0006] Determine the N factor levels for the coolant flow rate parameter and the factor levels for each structural parameter among the structural parameters;

[0007] Single-factor experiments were conducted based on the factor levels of each structural parameter to obtain the comprehensive heat transfer performance of each structural parameter at each factor level.

[0008] The N factor levels with the greatest overall heat transfer performance among all structural parameters were selected. Orthogonal experiments were conducted based on the N factor levels with the greatest overall heat transfer performance among all structural parameters and the N factor levels of the coolant flow rate parameter. Range analysis was performed on the results of the orthogonal experiments to obtain the optimal combination of target design parameters.

[0009] Preferably, the curved surface microstructure microchannel heat exchanger includes: a heat exchange substrate, in which multiple rectangular microchannels extending along its width direction are uniformly formed, and both ends of each microchannel extend to the outer surface of the heat exchange substrate to form an inlet and an outlet; the bottom wall of each microchannel is provided with multiple curved microstructures uniformly arranged along its length direction; wherein, the curved microstructure is a column or a groove, and the cross-section of the curved microstructure is crescent-shaped, with the convex surface of the crescent-shaped structure facing the inlet and the concave surface of the crescent-shaped structure facing the outlet.

[0010] Preferably, the heat exchange substrate includes a base plate and a cover plate. The base plate has a plurality of rectangular microgrooves with open top surfaces. Each microgroove extends along the width direction of the heat exchange substrate, and both ends extend to the outer surface of the heat exchange substrate to form an inlet and an outlet. The cover plate is closed to the substrate so that each microgroove between the cover plate and the substrate forms a microchannel. Curved surface topology microstructures are all disposed on the bottom wall of the microgroove.

[0011] Preferably, the length of the microchannel is 10 mm, the width of the microchannel is 0.5 mm, the height is 0.7 mm, and the spacing between the microchannels is 0.4 mm; the lateral length of the curved microstructure is 0.1 mm-0.3 mm, the longitudinal length of the curved microstructure is 0.1 mm-0.3 mm, and the height of the curved microstructure is -0.25 mm-0.3 mm.

[0012] Preferably, the longitudinal length of the curved microstructure is 0.25 mm, the transverse length is 0.2 mm, and the height is 0.15 mm.

[0013] Preferably, single-factor experiments are conducted based on the factor levels of each structural parameter to obtain the comprehensive heat transfer performance of each structural parameter at each factor level, specifically including:

[0014] For each factor level of each structural parameter, a three-dimensional geometric model of the surface microchannel heat exchanger with curved topology is established. Boundary conditions and material property parameters are set for the three-dimensional geometric model of the surface microchannel heat exchanger with curved topology. The three-dimensional geometric model of the surface microchannel heat exchanger with curved topology is meshed to obtain a mesh model. The heat transfer capacity is simulated and calculated on the mesh model to obtain the heat transfer capacity simulation parameters. Based on the heat transfer capacity simulation parameters of each structural parameter at each factor level, the comprehensive heat transfer performance of each structural parameter at each factor level is obtained.

[0015] Preferably, an orthogonal experiment is conducted based on N factor levels that maximize the overall heat transfer performance among various structural parameters and N factor levels of the coolant flow rate parameter, specifically including:

[0016] Based on the N factor levels that maximize the overall heat transfer performance among various structural parameters and the N factor levels of the coolant flow rate parameter, an orthogonal experimental scheme is designed.

[0017] For each experimental scheme in the orthogonal experimental design, a three-dimensional geometric model of the surface microchannel heat exchanger with curved topology microstructure is established. Boundary conditions and material property parameters are set for the three-dimensional geometric model of the surface microchannel heat exchanger with curved topology microstructure. The three-dimensional geometric model of the surface microchannel heat exchanger with curved topology microstructure is meshed to obtain a mesh model. The heat transfer capacity is simulated and calculated on the mesh model to obtain the heat transfer capacity simulation parameters. Based on the heat transfer capacity simulation parameters, the comprehensive heat transfer performance is obtained.

[0018] Preferably, the heat transfer capacity is simulated on the mesh model to obtain the heat transfer capacity simulation parameters, specifically including: establishing a set of physical field control equations based on the three-dimensional geometric model after mesh generation; solving the set of physical field control equations to obtain the heat transfer capacity simulation parameters; wherein, the heat transfer capacity simulation parameters include the pressure and temperature at the inlet and outlet of each microchannel.

[0019] Preferably, the boundary conditions of the physical field include: setting the boundary condition of the microchannel inlet as a velocity inlet, setting the boundary condition of the microchannel outlet as a pressure outlet, using the bottom surface of the microchannel as a heated wall with a fixed heat flux density, and using the remaining surfaces of the microchannel as adiabatic non-heated walls; and using no-slip and conjugate heat transfer conditions at the solid-liquid contact surface.

[0020] Preferably, the three-dimensional geometric model is meshed to obtain a mesh model, specifically including:

[0021] The three-dimensional geometric model is divided into domains to obtain solid domains and fluid domains. Unstructured tetrahedral meshes are used to mesh the solid domains and fluid domains respectively. In the meshing process, the mesh between the contact surfaces of the solid domain and the fluid domain is expanded and used as a boundary layer, and the mesh density of the fluid domain is greater than that of the solid domain.

[0022] In this invention, the proposed parameter optimization method for curved topology microstructure surface microchannel heat exchangers optimizes the target design parameters of the designed curved topology microstructure surface microchannel heat exchanger through single-factor experiments and orthogonal experiments. This balances the microchannel heat exchange efficiency and flow resistance, enabling the curved topology microstructure surface microchannel heat exchanger to have better heat exchange effect and lower flow resistance, and the highest comprehensive heat exchange performance. The higher the comprehensive heat exchange performance, the higher the overall performance of the microchannel heat exchanger. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the surface microchannel heat exchanger with curved topology microstructure in one embodiment of the present invention (the cover plate is not shown).

[0024] Figure 2This is a schematic diagram of the curved surface microstructure in one embodiment of the present invention.

[0025] Figure 3 Temperature distribution contour plots of MC-NW microstructures with different longitudinal lengths; where (a) represents the microstructure height. (b) indicates the microstructure height .

[0026] Figure 4 Nusselt number curves for MC-NW microstructures with different longitudinal lengths.

[0027] Figure 5 Temperature distribution contour plots of MC-NW microstructures with different lateral lengths; where (a) represents the microstructure height. (b) indicates the microstructure height .

[0028] Figure 6 Nusselt number curves for MC-NW microstructures with different lateral lengths.

[0029] Figure 7 Temperature distribution contour plots of MC-NW with different microstructure heights; where (a) represents the microstructure height. (b) indicates the microstructure height .

[0030] Figure 8 Nusselt number curves for MC-NW with different microstructure heights.

[0031] Figure 9 The pressure distribution contour plots of MC-NW microstructures with different longitudinal lengths are shown; where (a) represents the height of the microstructure. (b) indicates the microstructure height .

[0032] Figure 10 The friction coefficient curves are shown for MC-NW microstructures with different longitudinal lengths.

[0033] Figure 11 The pressure distribution contour plots of MC-NW microstructures with different transverse lengths are shown; where (a) represents the microstructure height. (b) indicates the microstructure height .

[0034] Figure 12 The friction coefficient curves are shown for MC-NW microstructures with different transverse lengths.

[0035] Figure 13The pressure distribution contour plots of MC-NW with different microstructure heights are shown; where (a) represents the microstructure height. (b) indicates the microstructure height .

[0036] Figure 14 The friction coefficient curves are shown for MC-NW with different microstructure heights.

[0037] Figure 15 This is a schematic diagram of the overall heat transfer performance of MC-NW microstructures with different longitudinal lengths.

[0038] Figure 16 This is a schematic diagram of the overall heat transfer performance of MC-NW microstructures with different transverse lengths.

[0039] Figure 17 This is a schematic diagram showing the overall heat transfer performance of MC-NW with different microstructure heights.

[0040] Figure 18 The influence trends of four experimental factors on the overall heat transfer performance of MC-NW are shown; where (a) is the longitudinal length, (b) is the transverse length, (c) is the microstructure height, and (d) is the water flow velocity. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] This invention proposes a method for optimizing the parameters of a surface microchannel heat exchanger with a curved topological microstructure, comprising:

[0043] Determine the target design parameters for the surface microchannel heat exchanger with curved topology microstructure; the target design parameters include structural parameters and coolant flow rate parameters, and the structural parameters include the length, width and height of the curved microstructure;

[0044] Determine the N factor levels for the coolant flow rate parameter;

[0045] Determine the factor level of each structural parameter in the structural parameters;

[0046] Single-factor experiments were conducted based on the factor levels of each structural parameter to obtain the comprehensive heat transfer performance of each structural parameter at each factor level.

[0047] Screening out the comprehensive heat transfer performance among various structural parameters The largest N factor levels,

[0048] Based on the comprehensive heat transfer performance of each structural parameter An orthogonal experiment was conducted on the N maximum factor levels and the N factor levels of the coolant flow rate parameter;

[0049] Range analysis was performed on the results of the orthogonal experiment to obtain the range ranking and optimal combination of each factor of the target design parameters.

[0050] This invention optimizes the target design parameters of the designed curved topology microstructure surface microchannel heat exchanger through single-factor experiments and orthogonal experiments to balance the microchannel heat exchange efficiency and flow resistance, so that the curved topology microstructure surface microchannel heat exchanger has better heat exchange effect and lower flow resistance, and the highest comprehensive heat exchange performance. The higher the comprehensive heat exchange performance, the higher the overall performance of the curved topology microstructure surface microchannel heat exchanger.

[0051] In this embodiment, the surface microchannel heat exchanger with curved topology microstructure includes: a heat exchange substrate, in which multiple rectangular microchannels extending along its width direction are uniformly formed, and both ends of each microchannel extend to the outer surface of the heat exchange substrate to form an inlet and an outlet; multiple curved microstructures are uniformly arranged along its length direction on the bottom wall of each microchannel; wherein, the curved microstructure is a column or a groove, and the cross-section of the curved microstructure is crescent-shaped, with the convex surface of the crescent-shaped structure facing the inlet and the concave surface of the crescent-shaped structure facing the outlet.

[0052] The introduction of the curved surface topology microstructure in this embodiment will generate large vortices in the channel, and the vortices are periodically distributed from left to right. This distribution of vortices can enhance the mixing of the liquid in the microchannel, enhance heat transfer, and greatly improve the heat dissipation efficiency of the rectangular microchannel heat sink.

[0053] like Figure 1 and Figure 2 As shown, in a further embodiment, the heat exchange substrate includes a base plate and a cover plate. The base plate has a plurality of rectangular microgrooves with open top surfaces. Each microgroove extends along the width direction of the heat exchange substrate, and both ends extend to the outer surface of the heat exchange substrate to form an inlet and an outlet. The cover plate covers the substrate so that each microgroove between the cover plate and the substrate forms a microchannel. Curved surface topology microstructures are all disposed on the bottom wall of the microgroove.

[0054] In this embodiment, single-factor experiments were conducted based on the factor levels of each structural parameter to obtain the comprehensive heat transfer performance of each structural parameter at each factor level. Specifically, it includes:

[0055] For each factor level of each structural parameter, a three-dimensional geometric model of the surface microchannel heat exchanger with curved topology is established; boundary conditions and material property parameters are set for the three-dimensional geometric model of the surface microchannel heat exchanger with curved topology; the three-dimensional geometric model of the surface microchannel heat exchanger with curved topology is meshed to obtain a mesh model; heat transfer capacity simulation calculation is performed on the mesh model to obtain heat transfer capacity simulation parameters; based on the heat transfer capacity simulation parameters, the comprehensive heat transfer performance is obtained.

[0056] In this embodiment, the overall heat transfer performance is considered based on the various structural parameters. An orthogonal experiment was conducted with the N highest factor levels and the N highest factor levels of the coolant flow rate parameter, specifically including:

[0057] Based on the comprehensive heat transfer performance of each structural parameter Design an orthogonal experimental scheme for the N largest factor levels and the N factor levels of the coolant flow rate parameter;

[0058] For each experimental scheme in the orthogonal experimental design, a three-dimensional geometric model of the surface microchannel heat exchanger with curved topology microstructure is established. Boundary conditions and material property parameters are set for the three-dimensional geometric model of the surface microchannel heat exchanger with curved topology microstructure. The three-dimensional geometric model of the surface microchannel heat exchanger with curved topology microstructure is meshed to obtain a mesh model. The heat transfer capacity is simulated and calculated on the mesh model to obtain the heat transfer capacity simulation parameters. Based on the heat transfer capacity simulation parameters, the comprehensive heat transfer performance is obtained. .

[0059] The three-dimensional geometric model in this embodiment includes: a heat exchange substrate, in which multiple rectangular microchannels extending along its width direction are uniformly formed, and both ends of each microchannel extend to the outer surface of the heat exchange substrate to form an inlet and an outlet; multiple curved microstructures are uniformly arranged along its length direction on the bottom wall of each microchannel; wherein, the curved microstructure is a column or a groove, and the cross-section of the curved microstructure is crescent-shaped, with the convex surface of the crescent-shaped microstructure facing the inlet and the concave surface of the crescent-shaped microstructure facing the outlet.

[0060] In a further embodiment, the heat exchange substrate includes a base plate and a cover plate. The base plate has a plurality of rectangular microgrooves with open top surfaces. Each microgroove extends along the width direction of the heat exchange substrate, and both ends extend to the outer surface of the heat exchange substrate to form an inlet and an outlet. The cover plate is closed to the substrate so that each microgroove between the cover plate and the substrate forms a microchannel. Curved surface topology microstructures are disposed on the bottom wall of the microgroove.

[0061] In a further specific embodiment, the base plate is made of aluminum alloy, the cover plate is made of acrylic, and deionized water is selected as the coolant.

[0062] In one specific embodiment, the total length of the base plate It is 10 mm, total height Length of a single microchannel ,width ,high The spacing between microchannels is 0.4 mm; the lateral length of the curved microstructure... The longitudinal length of the curved surface microstructure is 0.1 mm to 0.3 mm. The height of the curved surface microstructure is 0.1 mm to 0.3 mm. The value is -0.25 mm to 0.3 mm.

[0063] To better investigate the relationship between heat transfer efficiency and flow resistance in microchannels, two constant values ​​were set for the height of the microchannels during the single-factor experiment. Specifically, when the height of the curved microstructure... That is, when the curved surface microstructure is a cylinder, the lateral length of the microstructure is The longitudinal length is The microstructure spacing is When the microstructure is highly That is, when the curved surface microstructure is a groove, the lateral length of the curved surface microstructure is The longitudinal length is The microstructure spacing is .

[0064] The optimal combination obtained in this embodiment is: the longitudinal length of the curved microstructure is 0.25 mm, the transverse length is 0.2 mm, and the height is 0.15 mm.

[0065] The heat transfer capacity is simulated using a mesh model to obtain simulation parameters, specifically including:

[0066] Based on the three-dimensional geometric model after mesh generation, a set of physical field control equations is established; the physical field control equations are solved to obtain the simulation parameters of heat transfer capacity.

[0067] Therefore, the following boundary conditions are set in this embodiment for numerical simulation:

[0068] Set the boundary condition at the microchannel inlet to a velocity inlet. At the velocity inlet, , , In the formula, Indicates the import flow rate. Represents the flow velocity along the x-axis. Indicates the flow velocity along the y-axis. Represents the flow velocity along the z-axis. Indicates the inlet temperature;

[0069] Set the boundary condition for the microchannel outlet to a pressure outlet. At the pressure outlet, In the formula, This indicates export pressure;

[0070] The heat flux density at the bottom of the microchannel was fixed at 500,000. All non-heated wall surfaces are insulated; among them, , In the formula, This indicates the heat flux density at the bottom of the microchannel. This indicates the surface temperature of the solid excluding the heated surface. Indicates the direction of the temperature gradient.

[0071] The solid-liquid interface employs no-slip and conjugate heat transfer conditions: where, ;

[0072] In the formula, Represents the thermal conductivity of a solid. Indicates the thermal conductivity of the coolant. This indicates the temperature of the coolant.

[0073] In this embodiment, 6061 aluminum alloy is selected as the material for the microchannel solid domain. Its main physical properties are: density of 2800 ppm. Specific heat capacity is 880 Thermal conductivity is 130 .

[0074] In this embodiment, deionized water is selected as the working fluid. Its main physical properties are: density 998.2. Specific heat capacity is 4182 The thermal conductivity is 0.6. Viscosity is 0.001003 .

[0075] In a further embodiment, the three-dimensional geometric model is meshed to obtain a mesh model, specifically including:

[0076] The three-dimensional geometric model is divided into solid domains and fluid domains; unstructured tetrahedral meshes are used to mesh the solid domains and fluid domains respectively.

[0077] In the mesh generation, the mesh between the interface between the solid domain and the liquid domain is expanded and set as a boundary layer, and the mesh density of the fluid domain is greater than that of the solid domain.

[0078] During mesh generation, the number of meshes directly affects the reliability and efficiency of the computational results. Insufficient meshes significantly reduce simulation accuracy; while excessive mesh refinement can improve accuracy, it leads to an exponential increase in computation time and places higher demands on computer hardware performance. It is worth noting that once the mesh density reaches a critical value, further increasing the mesh number provides only a plateau in accuracy improvement, but the computational cost continues to rise. Therefore, before using a pre-set tetrahedral mesh for generation, conducting mesh independence verification is a necessary prerequisite to ensure the reliability of simulation results and the rational allocation of computational resources.

[0079] In this embodiment, before meshing the solid domain and fluid domain using unstructured tetrahedral meshes respectively, the following steps are also included:

[0080] Based on a single smooth rectangular microchannel, mesh independence verification is performed, and the preset number of meshes is determined when performing mesh generation based on the results of the mesh independence verification.

[0081] In a further embodiment, the set of governing equations for the physical field includes the continuity equation, the momentum conservation equation, the energy conservation equation for the coolant, and the energy conservation equation for the solid domain.

[0082] The continuity equation is: In the formula, , and These represent the three directions in a spatial rectangular coordinate system. , and These are the components of the coolant's velocity in three directions within a Cartesian coordinate system.

[0083] The momentum conservation equation is as follows:

[0084] ;

[0085] In the formula, It is the pressure of the coolant. and These are the dynamic viscosity and density of the coolant, respectively.

[0086] The energy conservation equation for the coolant is as follows:

[0087] ;

[0088] In the formula, It is the temperature of the coolant. It is the specific heat capacity of the coolant. It is the thermal conductivity of the coolant.

[0089] The energy conservation equation for the solid domain is: ;

[0090] In the formula, It is the solid temperature. It is the thermal conductivity of solids.

[0091] In a further embodiment, the physical field governing equations are solved to obtain simulation parameters of the heat transfer capacity, specifically including:

[0092] S1: Initialization: Assume an initial pressure field and velocity field Assume the initial velocity and pressure of the entire flow field are 0.

[0093] S2: Solve the momentum equation (prediction step): using the currently predicted pressure field Solving the momentum conservation equation yields a new velocity field that may not necessarily satisfy the continuity equation. ;

[0094] Taking the momentum equation in the x-direction as an example, its discretized form is:

[0095] ;

[0096] in, These are the discrete coefficients. It is the source item. It controls the volume of the body. The result of solving the momentum equation for grid element P x Predicting speed of direction, The prediction velocity of the adjacent grid cell nb;

[0097] Solving this equation yields the predicted velocity. Similarly, solve for the predicted velocities in the y and z directions;

[0098] S3: Solve the pressure correction equation (correction step): Define the pressure correction value. and speed correction value This makes the real physical quantity satisfy:

[0099] ;

[0100] Substituting the above relationship into the discretized continuity equation, we can derive the pressure correction value. Poisson's equation: ;in, For grid cells Pressure correction value, The pressure correction value for adjacent grid cell nb points. It is precisely from the predicted velocity field The unbalanced mass flow rate is calculated; the pressure correction equation is solved to obtain the pressure correction field. ;

[0101] S4: Update pressure and velocity: Correct the field using the obtained pressure. To update the pressure field and velocity field to make them closer to the solution that simultaneously satisfies the momentum equation and the continuity equation;

[0102] in, ; ;

[0103] In the formula, for x The discrete coefficients of the directional momentum equation are used to correct for velocity. ; For the corresponding The central coefficients of the directional momentum equation are used to correct for velocity. ; For the corresponding The central coefficients of the directional momentum equation are used to correct for velocity. ;

[0104] S5: Solve the energy equations and other scalar equations: After obtaining a relatively accurate velocity field at the current iteration step, solve the energy equations for the fluid and solid domains and update the temperature field. and ;

[0105] S6: Convergence Check: Check whether the residuals of all variables (velocity, pressure, temperature) are less than the set convergence criteria (e.g., ...). If convergence is not achieved, then the updated version will be used. As a new guess value Return to S2 and start a new round of iterations until convergence.

[0106] To ensure the accuracy of the design results, this embodiment verifies the reliability of the heat transfer capacity simulation method before performing heat transfer capacity simulation on the mesh model to obtain the heat transfer capacity simulation parameters.

[0107] Specifically, during the reliability verification process, the parameters used in the three-dimensional geometric model are imported into the preset theoretical microchannel pressure drop formula to obtain theoretical values, and then the theoretical values ​​are compared with the physical parameters obtained by solving, thereby verifying the accuracy of the physical parameters obtained by solving in this embodiment.

[0108] It is important to understand that the pre-defined theoretical microchannel pressure drop formula is as follows:

[0109] In the formula, Indicates microchannel pressure drop. Indicates the number of leaves of Possou. Indicates dynamic viscosity. Indicates the inlet velocity. Indicates the channel length. Represents the shape factor. Indicates fluid density, Indicates the hydraulic diameter.

[0110] The comprehensive heat transfer performance is obtained based on the heat transfer capacity simulation parameters, specifically including: calculating the microchannel pressure drop based on the inlet and outlet pressures in the heat transfer capacity simulation parameters; calculating the frictional resistance coefficient based on the microchannel pressure drop; calculating the convective heat transfer coefficient based on the inlet and outlet temperatures in the heat transfer capacity simulation parameters; calculating the Nusselt number based on the convective heat transfer coefficient; and calculating the comprehensive heat transfer performance based on the frictional resistance coefficient and the Nusselt number. .

[0111] The formula for calculating the microchannel pressure drop is: In the formula, This represents the inlet pressure of the microchannel. This indicates the outlet pressure of the microchannel.

[0112] Since the pressure drop of microchannels can also be expressed as friction resistance... It means that its expression is: ; In the formula, Represents the coefficient of frictional resistance. The density of the microchannel fluid. Represents gravitational acceleration. Indicates the friction resistance along the path. Indicates the length of the microchannel. The hydraulic diameter of the microchannel. This represents the inlet flow rate of the microchannel.

[0113] Therefore, the coefficient of frictional resistance The expression is: In the formula, Indicates microchannel pressure drop. The density of the microchannel fluid; The inlet flow rate of the microchannel. The hydraulic diameter of the microchannel.

[0114] Among them, the convective heat transfer coefficient The capacity of microchannels for convective heat transfer is expressed as: In the formula, These represent the solid-state temperature, fluid temperature, heat-receiving area of ​​the microchannel, heat exchange area between the liquid and solid, and heat flux density of the applied heat source, respectively.

[0115] Among them, Nusel number The Nusselt number is a dimensionless number representing the intensity of convective heat transfer. A larger Nusselt number indicates more active convective heat transfer. The formula for calculation is: In the formula, is the thermal conductivity of the coolant in the microchannel.

[0116] The overall heat transfer performance of a microchannel is expressed as the Nusselt number to the power of one-third of the friction coefficient, and its expression is: In the formula, Indicates overall heat exchange performance. , These represent the average Nusselt number and frictional resistance coefficient of the smooth rectangular microchannel, respectively. , These represent the average Nusselt number and frictional resistance coefficient of a rectangular microchannel with microstructures, respectively. The value indicates the degree of thermal efficiency relative to the pressure drop. A value greater than 1 indicates that the thermal performance is better than the pressure drop, while a value less than 1 indicates that the thermal performance is worse than the pressure drop. Therefore, if If the value is greater than 1, the design is considered acceptable.

[0117] In one specific embodiment, the factor levels of each structural parameter are shown in Table 1.

[0118] Table 1

[0119]

[0120] In the single-factor experiment, the temperature distribution cloud maps of MC-NW with different longitudinal length microstructures, transverse length microstructures, and microstructure heights are shown below. Figure 3 , Figure 5 and Figure 7 As shown, the Nusselt number curves of MC-NW with different longitudinal length microstructures, transverse length microstructures, and microstructure heights are respectively as follows: Figure 4 , Figure 6 and Figure 8 As shown, the cross-sectional pressure distribution cloud maps of MC-NW microstructures with different longitudinal lengths, transverse lengths, and microstructure heights are respectively as follows: Figure 9 , Figure 11 and Figure 13 As shown, the friction coefficient curves of MC-NW with different longitudinal length microstructures, transverse length microstructures, and microstructure heights are respectively as follows: Figure 10 , Figure 12 and Figure 14As shown in the diagrams, schematic diagrams illustrating the comprehensive heat transfer performance of MC-NW microstructures with different longitudinal lengths, transverse lengths, and microstructure heights are respectively shown in the diagrams. Figure 15 , Figure 16 and Figure 17 As shown.

[0121] from Figures 3-17 It can be seen that when the microstructure height is greater than 0, the microchannel heat exchange efficiency is high and the flow resistance is large, which is higher than that of the smooth flow channel; when the microstructure height is less than 0, the microchannel heat exchange efficiency is low and the flow resistance is less than that of the smooth flow channel, which has a drag reduction effect.

[0122] When the microstructure height is greater than 0, the overall heat transfer performance of the MC-NW first decreases and then increases with the increase of the longitudinal length of the microstructure. When the microstructure height is less than 0, the overall heat transfer performance of the MC-NW gradually decreases with the increase of the longitudinal length of the microstructure. When the microstructure height is greater than 0, the overall heat transfer performance of the MC-NW first increases and then decreases with the increase of the transverse length of the microstructure.

[0123] When the microstructure height is less than 0, the overall heat transfer performance of MC-NW gradually decreases with the increase of the lateral length of the microstructure. Under the same conditions, the overall heat transfer performance of MC-NW with a positive microstructure height is higher than that of MC-NW with a negative microstructure height within a certain range.

[0124] Table 2

[0125]

[0126] Since the water flow velocity consistently exhibits a linear relationship with the overall heat transfer performance of the microchannels within the laminar flow range, this paper selects three flow velocities—0.4 m / s, 1.2 m / s, and 2 m / s—covering the laminar flow range as the horizontal factors for the orthogonal experiment to confirm the strength of the influence of water flow velocity on the overall heat transfer performance. When N=3, according to Figures 3-17 The three factor levels with the greatest overall heat transfer performance among all structural parameters were selected. Table 2 shows the three factor levels with the greatest overall heat transfer performance for each structural parameter and the three factor levels for the coolant flow rate parameter.

[0127] Table 3

[0128]

[0129] According to Table 2, the L9(34) type orthogonal array was selected for the experimental design. The orthogonal experimental schemes are shown in Table 3, and the simulation results of each experimental scheme in the orthogonal experimental schemes are shown in Table 4. Among them, the hydraulic diameter of the channel in the orthogonal experiment is the same as that in the single-factor experiment, which is 0.583. The boundary condition parameter configuration of the orthogonal experiment in this study is consistent with that of the single-factor experiment. It should be noted that the interaction effect analysis between factors was not included in this orthogonal experimental design.

[0130] Table 4

[0131]

[0132] The orthogonal experiment range analysis table obtained from the range analysis in this embodiment is shown in Table 5. Based on the range... The effects of the following four experimental level factors on the overall heat transfer performance of rectangular microchannels were analyzed. The impact.

[0133] Table 5

[0134]

[0135] According to Table 5, the optimal combination is A3B3C1D3. Among these, the water flow velocity has the greatest impact on the overall heat transfer performance of the microchannel, followed by the microstructure height. The other two parameters have little impact on the overall heat transfer performance of the microchannel. That is, the target design parameters in this embodiment are: a longitudinal length of 0.25 mm, a transverse length of 0.2 mm, a height of 0.15 mm, and a coolant flow velocity of 2 m / s for the curved microstructure.

[0136] like Figure 18 As shown in the figures, (a), (b), (c), and (d) illustrate the changes in the overall heat transfer performance of the rectangular microchannel due to four experimental factors. The figures reveal that the effects of longitudinal length, transverse length, microstructure height, and flow velocity on the overall heat transfer performance differ. The longitudinal length of the microstructure initially decreases and then increases, with optimal overall heat transfer performance at a longitudinal length of 0.2 mm. The transverse length of the microstructure continuously increases, with optimal overall heat transfer performance at a transverse length of 0.25 mm. A greater height of the microstructure within the microchannel results in poorer overall heat transfer performance, with optimal performance at a microstructure height of 0.15 mm. Increasing the inlet flow velocity leads to a continuous increase in the overall heat transfer performance of the rectangular microchannel, with the highest overall heat transfer performance at an inlet flow velocity of 2 m / s. Furthermore, the flow velocity has the most significant impact on the overall heat transfer performance of the rectangular microchannel.

[0137] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for parameter optimization of a curved topological microstructured surface microchannel heat exchanger, characterized in that, The method comprises the following steps: determining target design parameters of the curved surface topological microstructure surface microchannel heat exchanger; wherein the target design parameters include structure parameters of the curved surface microstructure and cooling liquid flow rate parameters, and the structure parameters include length, width and height of the curved surface microstructure; determining N factor levels of the cooling liquid flow rate parameters; determining factor levels of each of the structure parameters; performing single-factor experiments according to the factor levels of each of the structure parameters to obtain comprehensive heat exchange performance of each of the structure parameters at each of the factor levels; and screening out N factor levels of each of the structure parameters with the maximum comprehensive heat exchange performance; performing orthogonal experiments and range analysis according to the N factor levels of each of the structure parameters with the maximum comprehensive heat exchange performance and the N factor levels of the cooling liquid flow rate parameters to obtain an optimal combination of the target design parameters.

2. The method of parameter optimization of a surface microchannel heat exchanger of a curved topological microstructure surface according to claim 1, characterized in that, The method comprises the following steps: The heat exchange substrate is internally and uniformly provided with a plurality of rectangular microchannels extending along the width direction thereof, and the two ends of each microchannel extend to the outer surface of the heat exchange substrate to form an inlet and an outlet; the bottom wall of each microchannel is provided with a plurality of curved surface microstructures uniformly arranged along the length direction thereof; the curved surface microstructure is a column or a groove, and the cross section of the curved surface microstructure is in the shape of a crescent, with the convex surface of the crescent facing the inlet and the concave surface of the crescent facing the outlet.

3. The method of parameter optimization of a surface microchannel heat exchanger of a curved topological microstructure surface according to claim 2, characterized in that, The heat exchange substrate comprises a base plate and a cover plate, and the base plate is uniformly provided with a plurality of rectangular microgrooves with open top surfaces; each microgroove extends along the width direction of the heat exchange substrate, and the two ends thereof extend to the outer surface of the heat exchange substrate to form an inlet and an outlet; the cover plate is combined with the base plate to form a microchannel in each microgroove between the cover plate and the base plate; and the curved surface topological microstructures are arranged on the groove bottom walls of the microgrooves.

4. The method of claim 2, wherein, The length of the microchannel is 10 mm, the width of the microchannel is 0.5 mm, the height of the microchannel is 0.7 mm, and the spacing between the microchannels is 0.4 mm; the transverse length of the curved surface microstructure is 0.1 mm-0.3 mm, the longitudinal length of the curved surface microstructure is 0.1 mm-0.3 mm, and the height of the curved surface microstructure is -0.25 mm-0.3 mm.

5. The method of parameter optimization of a surface microchannel heat exchanger with a curved topological microstructure surface according to claim 4, characterized in that, The longitudinal length of the curved surface microstructure is 0.25 mm, the transverse length of the curved surface microstructure is 0.2 mm, and the height of the curved surface microstructure is 0.15 mm.

6. The method of parameter optimization for a curved topological microstructured surface microchannel heat exchanger of claim 1, wherein, The single-factor experiments are performed according to the factor levels of each of the structure parameters to obtain the comprehensive heat exchange performance of each of the structure parameters at each of the factor levels, which specifically comprises the following steps: for each factor level of each of the structure parameters, a three-dimensional geometric model of the curved surface topological microstructure surface microchannel heat exchanger is established; boundary conditions and material physical property parameters are set for the three-dimensional geometric model of the curved surface topological microstructure surface microchannel heat exchanger; the three-dimensional geometric model of the curved surface topological microstructure surface microchannel heat exchanger is subjected to grid division processing to obtain a grid model; the grid model is subjected to heat exchange capacity simulation calculation to obtain heat exchange capacity simulation parameters; the comprehensive heat exchange performance of each of the structure parameters at each of the factor levels is obtained according to the heat exchange capacity simulation parameters of each of the structure parameters at each of the factor levels.

7. The method of parameter optimization of a surface microchannel heat exchanger of a curved topological microstructure surface according to claim 6, characterized in that, orthogonal experiments are performed according to the N factor levels of each of the structure parameters with the maximum comprehensive heat exchange performance and the N factor levels of the cooling liquid flow rate parameters, which specifically comprises the following steps: According to N factor levels of each structural parameter and N factor levels of the cooling liquid flow rate parameter, an orthogonal test scheme is designed; For each test scheme in the orthogonal test scheme, a three-dimensional geometric model of the curved surface topological microstructure surface microchannel heat exchanger is established; Boundary conditions and material physical property parameters are set for the three-dimensional geometric model of the curved surface topological microstructure surface microchannel heat exchanger; The three-dimensional geometric model of the curved surface topological microstructure surface microchannel heat exchanger is subjected to grid division processing to obtain a grid model; The grid model is subjected to heat exchange capacity simulation calculation to obtain heat exchange capacity simulation parameters; According to the heat exchange capacity simulation parameters, the comprehensive heat exchange performance is obtained.

8. The method of parameter optimization of a surface microchannel heat exchanger of a curved topological microstructure surface of claim 6, characterized in that, The heat exchange capacity simulation parameters are obtained by simulating the heat exchange capacity of the grid model, specifically including: Based on the three-dimensional geometric model subjected to grid division processing, physical field control equation sets are established; The physical field control equation sets are solved to obtain the heat exchange capacity simulation parameters; wherein the heat exchange capacity simulation parameters include the pressure and temperature of the inlet and the pressure and temperature of the outlet of each microchannel.

9. The method of claim 6, wherein, The boundary conditions of the physical field include: The boundary condition of the microchannel inlet is set as a velocity inlet, the boundary condition of the microchannel outlet is set as a pressure outlet, the bottom surface of the microchannel is set as a heating wall surface with a fixed heat flux, and the remaining surfaces of the microchannel are all non-heating wall surfaces with heat insulation; The contact surface between the solid and the liquid adopts no slip and conjugate heat transfer conditions.

10. The method of parameter optimization for a curved topological microstructured surface microchannel heat exchanger of claim 6, wherein, The three-dimensional geometric model is subjected to grid division processing to obtain a grid model, specifically including: The three-dimensional geometric model is subjected to domain division to obtain a solid domain and a fluid domain; Unstructured tetrahedral grids are used to divide the solid domain and the fluid domain respectively; In the grid division, the grids between the contact surface of the solid domain and the liquid domain are expanded and set as a boundary layer, and the density of the grids of the fluid domain is greater than that of the grids of the solid domain.

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