Evaluation method of plate-fin radiator based on double-grid model

Abstract

The invention relates to an evaluation method of a plate-fin radiator based on a double-grid model. The evaluation method comprises the following steps: establishing a simulation model of a corresponding representative unit based on geometric parameters of fins of the representative unit; simulating the cold side and the hot side of the simulation model to obtain a Reynolds number, a Prandtt number, a convective heat transfer coefficient, a viscous resistance coefficient and an inertial resistance coefficient of the representative unit; establishing a dual-grid model of the full-scale radiator based on the representative unit, and endowing the dual-grid model with a convective heat transfer coefficient, a viscous resistance coefficient and an inertial resistance coefficient of the representative unit; boundary conditions are given, the double-grid model is simulated, the outlet temperature of the hot side of the double-grid model is obtained, and when the outlet temperature is smaller than a threshold value, it is judged that the heat exchange performance of the radiator reaches the standard. According to the method, the dual-grid model of the full-scale radiator is established, the cold side and the hot side of the dual-grid model are simulated respectively, the calculation precision is improved while the calculation amount is reduced, and the working efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of vehicle thermal management, and particularly to an evaluation method for a plate-fin radiator based on a dual-grid model. Background Art

[0002] With the continuous development of special vehicles, the requirements for electro-mechanical composite high-power power devices of special vehicles are constantly increasing, making the layout of the engine compartment increasingly compact. Therefore, the structure and layout of the vehicle thermal management system are also becoming increasingly compact. The radiator is one of the most important parts of the vehicle thermal management system. The radiators of special vehicles usually adopt a plate-fin structure with a smaller fin pitch. This structure has a large flow resistance. Therefore, the performance of the radiator is reflected by flow parameters and heat transfer parameters.

[0003] In the development process of existing plate-fin radiators, the radiator as a whole is usually simulated, and then the heat transfer factor and flow factor are obtained through calculation, so as to obtain the JF factor; the heat transfer performance of the radiator is evaluated based on the magnitude of the JF factor. The existing simulation method for plate-fin radiators simulates the radiator as a whole, and it is necessary to calculate the JF factor to evaluate the heat transfer performance of the radiator, which increases the amount of calculation. Moreover, in the existing simulation model of plate-fin radiators, the flow parameters and heat transfer parameters need to be obtained relying on a large amount of experimental data. In the process of developing a new radiator, due to the lack of support of experimental data, the fitting accuracy of the flow parameters and heat transfer parameters for the heat transfer characteristics of the radiator is not high. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide an evaluation method for a plate-fin radiator based on a dual-grid model to solve the problems of large calculation amount during the simulation and evaluation of existing plate-fin radiators, and low fitting accuracy of the flow parameters and heat transfer parameters for the heat transfer characteristics of the radiator.

[0005] The present invention provides an evaluation method for a plate-fin radiator based on a dual-grid model, and the method includes the following steps:

[0006] Establish a simulation model of the representative unit based on the geometric parameters of the representative unit fin;

[0007] Simulate the cold side and the hot side of the simulation model to obtain the Reynolds number, Prandtl number, convective heat transfer coefficient, viscous resistance coefficient and inertial resistance coefficient of the representative unit;

[0008] Based on the representative unit, establish a dual-grid model of the full-scale radiator, and assign the convective heat transfer coefficient, viscous resistance coefficient and inertial resistance coefficient of the representative unit to the dual-grid model;

[0009] Given the boundary conditions, simulate the double-grid model to obtain the outlet temperature on its hot side. When the outlet temperature is less than the threshold value, it is determined that the heat transfer performance of the radiator meets the standard.

[0010] Furthermore, establish a grid model for the cold side and the hot side of the full-scale radiator respectively to obtain a double-grid model; assign the convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient of the representative cell's cold side to the cold-side grid model, and assign the convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient of the representative cell's hot side to the hot-side grid model.

[0011] Furthermore, given the boundary conditions for the cold side and the hot side of the double-grid model respectively; the boundary conditions are to give the temperature and velocity at the inlet, set the temperature gradient at the outlet to 0 and the pressure to 0, give the temperature at the bottom, and set the top as an adiabatic boundary and the two sides as periodic boundary conditions.

[0012] Furthermore, obtain the viscous resistance coefficient and inertial resistance coefficient of the representative cell through the following method:

[0013]

[0014] where F i is the source term of the momentum equation, i and j are the three directions of the Cartesian coordinate system, Δp is the pressure difference of the fluid flowing through the representative cell, L is the length of the representative cell along the flow direction, D ij is the diagonal matrix of the reciprocals of the viscous resistance coefficients in the i and j directions, C ij is the diagonal matrix of the reciprocals of the inertial resistance coefficients in the i and j directions, μ is the dynamic viscosity of the fluid, v j is the velocity of the fluid in the j direction, and ρ is the density of the fluid.

[0015] Furthermore, the convective heat transfer coefficient includes the cold-side convective heat transfer coefficient and the hot-side convective heat transfer coefficient. Obtain the convective heat transfer coefficient of the representative cell through the following method:

[0016]

[0017] where h h is the hot-side convective heat transfer coefficient, q is the total heat flux of the representative cell, A h is the hot-side heat transfer area, T h is the average temperature of the hot-side wall surface, T f is the average temperature of the edge grid, h c is the cold-side convective heat transfer coefficient, A c is the cold-side heat transfer area, and T c is the average temperature of the cold-side wall surface.

[0018] Furthermore, obtain the Reynolds number of the representative cell through the following method:

[0019]

[0020] Among them, is the fluid velocity at the inlet of the representative unit, d is the hydraulic diameter of the fluid flow channel of the representative unit, and Re is the Reynolds number.

[0021] Furthermore, the Prandtl number of the representative unit is obtained by the following method:

[0022]

[0023] Among them, C p is the specific heat capacity of the fluid, λ is the thermal conductivity of the fluid, and Pr is the Prandtl number.

[0024] Furthermore, the outlet temperature of the hot side is obtained by the following method:

[0025] Simulate the double-grid model to obtain the temperature of the hot-side grid;

[0026] According to the grid corresponding to the hot-side outlet, obtain the average temperature of the grid, and the average temperature is the outlet temperature of the hot side.

[0027] Furthermore, the temperature of the hot-side grid is obtained by the following method:

[0028]

[0029]

[0030]

[0031] Among them, is the Hamiltonian operator, T is the temperature of the grid, p is the pressure of the fluid flowing through the representative unit, and S is the energy source term.

[0032] Furthermore, the energy source term includes a hot-side energy source term and a cold-side energy source term. The hot-side energy source term, the cold-side energy source term, and the overall heat transfer coefficient are obtained by the following method:

[0033]

[0034] Among them, U is the overall heat transfer coefficient, T c , T h are the central temperatures of the grids at the same coordinate positions on the cold side and the hot side respectively, V is the volume of the grid, S h is the hot-side energy source term, and S c is the cold-side energy source term.

[0035] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0036] 1. The present invention improves the computational efficiency by establishing a dual-grid model of a full-scale radiator, simulating the cold side and the hot side of the dual-grid model respectively, reducing the computational amount while improving the computational accuracy.

[0037] 2. The present invention characterizes the flow parameters and heat transfer parameters of the radiator through the convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient on the cold side and the hot side of the representative unit, and assigns these parameters to the full-scale radiator through a UDF file, thereby improving the accuracy of the calculation results of the flow and heat transfer characteristics of the overall radiator.

[0038] 3. The present invention evaluates the heat transfer performance of the radiator through the outlet temperature on the hot side of the radiator, without calculating complex indicators, reducing the computational amount.

[0039] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the content specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings are only used for the purpose of showing specific embodiments and are not considered as limiting the present invention. Throughout the drawings, the same reference signs represent the same components.

[0041] Figure 1 is a flowchart of the evaluation method of the plate-fin radiator based on the dual-grid model according to an embodiment of the present invention;

[0042] Figure 2 is a schematic diagram of the representative unit of the plate-fin radiator according to an embodiment of the present invention;

[0043] Figure 3 is a schematic diagram of the cold side or the hot side of the full-scale radiator according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The following will specifically describe the preferred embodiments of the present invention with reference to the drawings. The drawings form a part of this application and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0045] A specific embodiment of the present invention discloses an evaluation method of a plate-fin radiator based on a dual-grid model. As Figure 1 shown, the method includes the following steps:

[0046] Step S1: Establish a simulation model of the corresponding representative unit based on the fin geometric parameters of the representative unit;

[0047] Step S2: Simulate the cold side and the hot side of the simulation model to obtain the Reynolds number, Prandtl number, convective heat transfer coefficient, viscous drag coefficient, and inertial drag coefficient of the representative unit;

[0048] Step S3: Based on the representative unit, establish a dual-grid model of the full-scale radiator, and assign the convective heat transfer coefficient, viscous drag coefficient, and inertial drag coefficient of the representative unit to the dual-grid model;

[0049] Step S4: Given the boundary conditions, simulate the dual-grid model to obtain the outlet temperature of its hot side. When the outlet temperature is less than the threshold, it is determined that the heat transfer performance of the radiator meets the standard.

[0050] Specifically, in step S1, a three-dimensional simulation model corresponding to the representative unit is obtained based on the fin geometric parameters of the representative unit. The fin geometric parameters of the representative unit include fin height, fin pitch, and fin thickness.

[0051] Specifically, as Figure 2 shown, the representative unit is a cuboid, divided into a cold side and a hot side, including a heat dissipation plate and fins. The geometric parameters of the fins on the cold side and the hot side are the same. The representative unit contains N fin single-period structures.

[0052] It can be understood that the plate-fin radiator is divided into a cold side and a hot side. The cold side and the hot side are isolated and conduct heat through a metal plate. Both the cold side and the hot side have fins arranged uniformly, and the distance between the fins is the fin pitch. The hot side dissipates heat through the circulation of water, and the cold side dissipates heat through the circulation of air. Therefore, the fluid on the hot side is water, and the fluid on the cold side is air. Since the fins are a periodic array structure, to meet the representativeness, it is set that the representative unit contains N fin single-period structures. The fewer the fin single-period structures contained in the representative unit, the smaller the simulation calculation amount and the faster the calculation speed.

[0053] Specifically, in step S2, when simulating the cold side and the hot side of the simulation model, the Reynolds number of the representative unit is obtained by the following method:

[0054]

[0055] Among them, is the inlet fluid velocity of the representative unit, d is the hydraulic diameter of the fluid flow channel of the representative unit, and Re is the Reynolds number.

[0056] Furthermore, when simulating the cold side and the hot side of the simulation model, the Prandtl number of the representative unit is obtained by the following method:

[0057]

[0058] Among them, C p$c_p$ is the specific heat capacity of the fluid, $\lambda$ is the thermal conductivity of the fluid, and Pr is the Prandtl number.

[0059] Specifically, during the simulation, the hot-side inlet temperature is set to 120 °C, and the inlet water flow rate is 5 m / s; the cold-side inlet temperature is 35 °C, and the inlet air flow rate is 25 m / s. Through the above formulas, the Reynolds numbers and Prandtl numbers of the cold side and hot side of the simulation model can be obtained respectively.

[0060] Furthermore, when simulating the cold side and hot side of the simulation model, the viscous resistance coefficient and inertial resistance coefficient of the representative unit are obtained by the following method:

[0061]

[0062] where $F$ i is the source term of the momentum equation, $i$ and $j$ are the three directions of the Cartesian coordinate system, $\Delta p$ is the pressure difference of the fluid flowing through the representative unit, $L$ is the length of the representative unit along the flow direction, and $D$ ij is the diagonal matrix of the reciprocals of the viscous resistance coefficients in the $i$ and $j$ directions, $C$ ij is the diagonal matrix of the reciprocals of the inertial resistance coefficients in the $i$ and $j$ directions, $\mu$ is the dynamic viscosity of the fluid, $v$ j is the velocity of the fluid in the $j$ direction, and $\rho$ is the density of the fluid.

[0063] Specifically, the cold side and hot side of the representative unit are regarded as anisotropic porous media. The relationship between the fluid velocity and pressure of the anisotropic porous media can be described by the Darcy-Forchheimer law, and its momentum equation is as shown in the above formula. Similarly to the Reynolds number and Prandtl number, through the above formula, the viscous resistance coefficient and inertial resistance coefficient of the cold side and hot side of the simulation model can be obtained respectively.

[0064] Furthermore, the convective heat transfer coefficient includes the cold-side convective heat transfer coefficient and the hot-side convective heat transfer coefficient. When simulating the cold side and hot side of the simulation model, the convective heat transfer coefficient of the representative unit is obtained by the following method:

[0065]

[0066] where $h$ h is the hot-side convective heat transfer coefficient, $q$ is the total heat flux of the representative unit, $A$ h is the hot-side heat transfer area, $T$ h is the average temperature of the hot-side wall surface, $T$ f is the average temperature of the edge grid, $h$ c is the cold-side convective heat transfer coefficient, $A$ c is the cold-side heat transfer area, and $T$ c is the average temperature of the cold-side wall surface.

[0067] Specifically, in step S3, the representative unit is expanded according to the actual size requirement of the radiator to obtain a full-scale radiator.

[0068] Furthermore, a grid model is respectively established for the cold side and the hot side of the full-scale radiator to obtain a dual-grid model; the convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient of the cold side of the representative unit are assigned to the cold-side grid model, and the convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient of the hot side of the representative unit are assigned to the hot-side grid model.

[0069] Specifically, a grid model is respectively established for the cold side and the hot side of the full-scale radiator in the fluent simulation software to obtain a dual-grid model. Based on the obtained convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient, a UDF file is written, and in the fluent simulation software, the convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient of the cold side of the representative unit are assigned to the cold-side grid model through the UDF file, and the convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient of the hot side of the representative unit are assigned to the hot-side grid model.

[0070] Specifically, in step S4, as Figure 3 shown, boundary conditions are respectively given to the cold side and the hot side of the dual-grid model; the boundary conditions are to give the temperature and velocity at the inlet, set the temperature gradient at the outlet to 0 and the pressure to 0, give the temperature at the bottom, and set the top as an adiabatic boundary and the two sides as periodic boundary conditions. Based on the boundary conditions, the dual-grid model is simulated.

[0071] It can be understood that the cold side and the hot side of the radiator are symmetric. Meshes of the same size are established for the cold side and the hot side, and by respectively assigning the relevant coefficients of the cold side and the hot side to the meshes, the energy source terms and outlet temperatures of the cold side and the hot side are obtained through simulation. This not only considers the actual situation of the non-constant temperature at the interface between the cold side and the hot side, thus improving the calculation accuracy, but also only simulates one side of the radiator each time, thereby reducing the calculation amount.

[0072] Furthermore, the outlet temperature of the hot side is obtained through the following method:

[0073] The dual-grid model is simulated to obtain the temperature of the hot-side mesh;

[0074] According to the mesh corresponding to the outlet of the hot side, the average temperature of the mesh is obtained, and the average temperature is the outlet temperature of the hot side.

[0075] Furthermore, the temperature of the hot-side mesh is obtained through the following method:

[0076]

[0077]

[0078]

[0079] Among them, is the Hamiltonian operator, T is the temperature of the grid, p is the pressure of the fluid flowing through the representative cell, and S is the energy source term.

[0080] It can be understood that substituting the pressure of the fluid flowing through the hot side of the representative cell, the density of the hot side fluid, the velocity of the hot side fluid, the specific heat capacity of the hot side fluid, the thermal conductivity of the hot side fluid, and the hot side energy source term into the above formula gives the temperature of the hot side grid.

[0081] Furthermore, the energy source term includes a hot side energy source term and a cold side energy source term. The hot side energy source term, the cold side energy source term, and the overall heat transfer coefficient are obtained through the following method:

[0082]

[0083] Among them, U is the overall heat transfer coefficient, T c and T h are the central temperatures of the grids at the same coordinate position on the cold side and the hot side respectively, V is the volume of the grid, S h is the hot side energy source term, and S c is the cold side energy source term.

[0084] It can be understood that the present invention characterizes the flow parameters and heat transfer parameters of the radiator through the convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient on the cold side and the hot side of the representative cell, and assigns these parameters to the full-scale radiator through a UDF file, thereby improving the accuracy of the calculation results of the overall flow and heat transfer characteristics of the radiator.

[0085] It can be understood that the smaller the outlet temperature of the hot side of the radiator, the greater the temperature difference from the inlet temperature of the hot side, i.e., the heat source temperature. Therefore, the better the heat dissipation performance. When the outlet temperature is less than the threshold value, it is determined that the heat exchange performance of the radiator meets the standard; otherwise, the fin geometric parameters need to be modified and the simulation is carried out again until the heat exchange performance of the radiator meets the standard. The present invention evaluates the heat exchange performance of the radiator through the outlet temperature of the hot side of the radiator, without calculating complex indicators, reducing the amount of calculation.

[0086] Compared with the prior art, the beneficial effects of the evaluation method of the plate fin radiator based on the dual grid model provided by the present invention are as follows:

[0087] 1. By establishing a dual grid model of the full-scale radiator and simulating the cold side and the hot side of the dual grid model respectively, the present invention improves the calculation accuracy while reducing the amount of calculation, and improves the work efficiency.

[0088] 2. The flow parameters and heat transfer parameters of the radiator are characterized by the convective heat transfer coefficient, viscous resistance coefficient, and inertial resistance coefficient on the cold side and the hot side of the representative unit. The parameters are assigned to the full-scale radiator through the UDF file, thereby improving the accuracy of the calculation results of the flow and heat transfer characteristics of the overall radiator.

[0089] 3. The heat transfer performance of the radiator is evaluated by the outlet temperature on the hot side of the radiator, without the need to calculate complex indexes, reducing the calculation amount.

[0090] Those skilled in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. Among them, the computer-readable storage medium is a disk, an optical disc, a read-only memory, or a random access memory, etc.

[0091] The above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. An evaluation method for a plate-fin radiator based on a dual-grid model, characterized in that, The method includes the following steps: Based on the geometric parameters of the representative unit fin, establish a simulation model of the corresponding representative unit; Simulate the cold side and the hot side of the simulation model to obtain the Reynolds number, Prandtl number, convective heat transfer coefficient, viscous drag coefficient, and inertial drag coefficient of the representative unit; Based on the representative unit, establish a dual-grid model of the full-scale radiator, and assign the convective heat transfer coefficient, viscous drag coefficient, and inertial drag coefficient of the representative unit to the dual-grid model; Given the boundary conditions, simulate the dual-grid model to obtain the outlet temperature of its hot side. When the outlet temperature is less than the threshold, it is determined that the heat transfer performance of the radiator meets the standard.

2. The evaluation method for a plate-fin radiator based on a dual-grid model according to claim 1, characterized in that, Respectively establish grid models for the cold side and the hot side of the full-scale radiator to obtain a dual-grid model; assign the convective heat transfer coefficient, viscous drag coefficient, and inertial drag coefficient of the cold side of the representative unit to the cold-side grid model, and assign the convective heat transfer coefficient, viscous drag coefficient, and inertial drag coefficient of the hot side of the representative unit to the hot-side grid model.

3. The evaluation method for a plate-fin radiator based on a dual-grid model according to claim 1, characterized in that, Respectively give boundary conditions for the cold side and the hot side of the dual-grid model; the boundary conditions are to give the temperature and velocity at the inlet, set the temperature gradient at the outlet to 0 and the pressure to 0, give the temperature at the bottom, and set the top as an adiabatic boundary and the two sides as periodic boundary conditions.

4. The evaluation method for a plate-fin radiator based on a dual-grid model according to claim 1, characterized in that, The viscous drag coefficient and inertial drag coefficient of the representative unit are obtained by the following method: Among them, F i is the source term of the momentum equation, i and j are the three directions of the Cartesian coordinate system, Δp is the pressure difference of the fluid flowing through the representative unit, L is the length of the representative unit along the flow direction, D ij is the diagonal matrix of the reciprocals of the viscous drag coefficients in the i and j directions, C ij is the diagonal matrix of the reciprocals of the inertial drag coefficients in the i and j directions, μ is the dynamic viscosity of the fluid, v j is the velocity of the fluid in the j direction, and ρ is the density of the fluid.

5. The evaluation method for a plate-fin radiator based on a dual-grid model according to claim 1, characterized in that, The convective heat transfer coefficient includes the cold-side convective heat transfer coefficient and the hot-side convective heat transfer coefficient. The convective heat transfer coefficient of the representative unit is obtained by the following method: Among them, h h is the convective heat transfer coefficient on the hot side, q is the total heat flux of the representative unit, and A h is the heat transfer area on the hot side, T h is the average temperature of the hot side wall surface, T f is the average temperature of the edge grid, h c is the convective heat transfer coefficient on the cold side, and A c is the heat transfer area on the cold side, T c is the average temperature of the cold side wall surface.

6. The evaluation method for a plate-fin radiator based on a dual-grid model according to claim 1, characterized in that, The Reynolds number of the representative unit is obtained by the following method: Among them, is the fluid velocity at the entrance of the representative unit, d is the hydraulic diameter of the fluid flow channel of the representative unit, and Re is the Reynolds number.

7. The evaluation method for a plate-fin radiator based on a dual-grid model according to claim 1, characterized in that, The Prandtl number of the representative unit is obtained by the following method: where C p is the specific heat capacity of the fluid, λ is the thermal conductivity of the fluid, and Pr is the Prandtl number.

8. The evaluation method for a plate-fin radiator based on a dual-grid model according to claim 1, characterized in that, The outlet temperature of the hot side is obtained by the following method: Simulate the dual-grid model to obtain the temperature of its hot-side grid; According to the grid corresponding to the hot-side outlet, obtain the average temperature of the grid, and the average temperature is the outlet temperature of the hot side.

9. The evaluation method for a plate-fin radiator based on a dual-grid model according to claim 8, characterized in that, The temperature of the hot-side grid is obtained by the following method: ▽·v＝0 ρ(v·▽)v=-▽p+μ▽ 2 v, Where, ▽ is the Hamiltonian operator, T is the temperature of the grid, p is the pressure of the fluid flowing through the representative unit, and S is the energy source term.

10. The evaluation method of the plate-fin heat sink based on the dual grid model according to claim 9, characterized in that, The energy source term includes the hot-side energy source term and the cold-side energy source term. The hot-side energy source term, the cold-side energy source term, and the total heat transfer coefficient are obtained by the following method: where U is the overall heat transfer coefficient, T c , T h are the center temperatures of the grids at the same coordinate positions on the cold side and the hot side respectively, V is the volume of the grid, S h is the energy source term on the hot side, and S c is the energy source term on the hot side.

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