CN116757108A

CN116757108A - Simulation method, device and equipment of heat exchanger

Info

Publication number: CN116757108A
Application number: CN202310618229.0A
Authority: CN
Inventors: 刘晓晶; 柴翔; 熊进标; 张滕飞; 何辉
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2023-05-29
Filing date: 2023-05-29
Publication date: 2023-09-15
Anticipated expiration: 2043-05-29
Also published as: CN116757108B

Abstract

The embodiment of the application discloses a simulation method, a device and equipment of a heat exchanger. Wherein the method comprises the following steps: acquiring an initial structural model of the heat exchanger, and determining an optimized structural model according to the initial structural model; the initial structural model comprises a plurality of first heat transfer pipes, the optimized structural model comprises a plurality of second heat transfer pipes, the sum of the outer wall surface areas of the plurality of second heat transfer pipes is equal to the sum of the outer wall surface areas of the plurality of first heat transfer pipes, and the inner diameter of the second heat transfer pipes is larger than the inner diameter of the first heat transfer pipes; dividing the optimized structure model to obtain a corresponding grid; determining simulation parameters corresponding to the working conditions to be simulated of the heat exchanger; and inputting the grid and the simulation parameters into a preset computational fluid dynamics model, and determining a simulation result of the working condition to be simulated. According to the method, the working conditions of the heat exchanger are simulated, so that the simulated calculated amount can be reduced, and the simulation effect of the heat exchanger is improved.

Description

Simulation method, device and equipment of heat exchanger

Technical Field

The present application relates to the field of equipment simulation technologies, and in particular, to a method, an apparatus, and an equipment for simulating a heat exchanger.

Background

In the context of actively developing new stack studies such as micro-stacks, thorium-based molten salt stacks, lead-based alloy cooled reactors, and the like, the project of CiADS (China Initiative Accelerator Driven System, accelerator-driven transmutation research devices) has been developed, liquid lead-bismuth alloy can be adopted as a coolant, and fast neutrons are mainly used to maintain a chain fission reaction in the reactor, and such a reactor is often called a lead-cooled fast reactor, also called a lead-based fast reactor.

For the development of lead-based fast reactors, the development of various main equipment including heat exchangers is a key link. The heat exchanger is a device for transferring part of heat of hot fluid to cold fluid, is one of important devices widely applied in the nuclear energy field, and has the main functions of ensuring the specific temperature required by the process on the medium and improving the energy utilization rate. Therefore, the computational fluid dynamics analysis is carried out on the heat exchanger, and the influence of the flow speed, the temperature, the heat exchange coefficient, the thermal stress and the like on the functions of the heat exchanger is explored, so that the method has great significance for improving the efficiency and the safety of the nuclear power plant.

However, the conventional scheme for performing computational fluid dynamics analysis on the heat exchanger has the problems of large simulation calculation amount and unsatisfactory simulation effect.

Disclosure of Invention

The embodiment of the application aims to provide a simulation method, a device and equipment of a heat exchanger, which are used for solving the problems of large simulation calculation amount and non-ideal simulation effect of a simulation scheme of the conventional heat exchanger model.

In order to solve the technical problems, the embodiment of the application is realized as follows:

in a first aspect, an embodiment of the present application provides a method for simulating a heat exchanger, including: acquiring an initial structural model of the heat exchanger, and determining an optimized structural model according to the initial structural model; the heat exchanger comprises a first loop and a second loop for heat exchange; the initial structural model comprises a plurality of first heat transfer pipes, the optimized structural model comprises a plurality of second heat transfer pipes, the sum of the outer wall surface areas of the plurality of second heat transfer pipes is equal to the sum of the outer wall surface areas of the plurality of first heat transfer pipes, and the inner diameter of the second heat transfer pipes is larger than the inner diameter of the first heat transfer pipes; dividing the optimized structure model to obtain a corresponding grid; the optimized structure model comprises a primary loop fluid flow channel model, a solid heat transfer pipe model and a secondary loop fluid flow channel model; determining simulation parameters corresponding to the working conditions to be simulated of the heat exchanger; the simulation parameters include at least one of: calculating a fluid dynamic model setting parameter, a material parameter corresponding to the heat exchanger and a boundary condition parameter; inputting the grid and the simulation parameters into a preset computational fluid dynamics model, and determining a simulation result of the working condition to be simulated; the simulation result comprises at least one of the following: a temperature field simulation result, a thermal stress field simulation result and a speed field simulation result.

In a second aspect, an embodiment of the present application provides an analog device for a heat exchanger, including: the model determining module is used for obtaining an initial structure model of the heat exchanger and determining an optimized structure model according to the initial structure model; the heat exchanger comprises a first loop and a second loop for heat exchange; the initial structural model comprises a plurality of first heat transfer pipes, the optimized structural model comprises a plurality of second heat transfer pipes, the sum of the outer wall surface areas of the plurality of second heat transfer pipes is equal to the sum of the outer wall surface areas of the plurality of first heat transfer pipes, and the inner diameter of the second heat transfer pipes is larger than the inner diameter of the first heat transfer pipes; the grid dividing module is used for dividing the optimized structure model to obtain corresponding grids; the optimized structure model comprises a primary loop fluid flow channel model, a solid heat transfer pipe model and a secondary loop fluid flow channel model; the parameter determining module is used for determining simulation parameters corresponding to the working conditions to be simulated of the heat exchanger; the working condition to be simulated comprises at least one of the following: steady-state operation working condition, main pump idle transient working condition, primary loop lost flow non-shutdown transient working condition; the simulation parameters include at least one of: calculating a fluid dynamic model setting parameter, a material parameter corresponding to the heat exchanger and a boundary condition parameter; the simulation result determining module is used for inputting the grid and the simulation parameters into a preset computational fluid dynamics model and determining a simulation result of the working condition to be simulated; the simulation result comprises at least one of the following: a temperature field simulation result, a thermal stress field simulation result and a speed field simulation result.

In a third aspect, an embodiment of the present application provides an analog device for a heat exchanger, including: a processor; and a memory arranged to store computer executable instructions which, when executed, cause the processor to implement a method of simulating a heat exchanger of the first aspect described above.

In a fourth aspect, an embodiment of the present application provides a storage medium storing computer executable instructions that when executed implement a method of simulating a heat exchanger according to the first aspect.

By adopting the technical scheme of the embodiment of the application, an optimized structure model is obtained by optimizing an initial structure model, the sum of the surface areas of the outer walls of the heat transfer tubes of the optimized structure model is equal to the sum of the surface areas of the outer walls of the heat transfer tubes of the initial structure model, the inner diameter of the heat transfer tubes is larger than the inner diameter of the heat transfer tubes of the initial structure model, then the optimized structure model is divided to obtain corresponding grids, simulation parameters corresponding to the working condition to be simulated of the heat exchanger are determined, finally the grids and the simulation parameters are input into a preset computational fluid dynamics model, and the simulation result of the working condition to be simulated is determined, wherein the simulation result comprises at least one of the following: a temperature field simulation result, a thermal stress field simulation result and a speed field simulation result. According to the method, the working conditions of the heat exchanger are simulated, so that the simulated calculated amount can be reduced, and the simulation effect of the heat exchanger is improved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic flow chart of a method of modeling a heat exchanger in accordance with an embodiment of the application;

FIG. 2 is a schematic illustration of an optimized heat exchanger configuration according to one embodiment of the present application;

FIG. 3 is a grid schematic of a thermal transfer unit ensemble model in accordance with an embodiment of the present application;

FIG. 4 is a grid schematic of a bottom surface of a heat exchanger mold according to an embodiment of the present application;

FIG. 5 is a graph showing the average temperature simulation results of a loop outlet according to an embodiment of the present application;

FIG. 6 is a schematic diagram of another simulation result of the average temperature of the outlet of the loop according to one embodiment of the present application;

FIG. 7 is a schematic diagram showing the average temperature simulation results of the two-loop outlet according to an embodiment of the present application;

FIG. 8 is a schematic diagram of a heat exchanger simulator according to an embodiment of the application;

fig. 9 is a schematic structural view of a simulation apparatus of a heat exchanger according to an embodiment of the present application.

Detailed Description

In order to make the technical solution of the present application better understood by those skilled in the art, the technical solution of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, shall fall within the scope of the application.

The CiADS lead-based fast reactor main heat exchanger generally adopts a shell-and-tube structure, and the shell-and-tube structure has the advantages of simplicity, stability, convenience in cleaning, high temperature resistance, wide application, mature technology and the like. The embodiment of the application carries out digital simulation analysis and research on the shell-and-tube main heat exchanger based on the CiADS. Optionally, the FLUENT commercial fluid dynamics software package and ANSYS mechanical analysis software are adopted to perform multi-physical field coupling analysis, and steady-state temperature, speed and thermal stress analysis and simulation of two conditions of reduced primary coolant flow of the small lead-based fast reactor are performed.

Fig. 1 is a schematic flow chart of a simulation method of a heat exchanger according to an embodiment of the present invention, as shown in fig. 1, the method includes:

step S102, an initial structural model of the heat exchanger is obtained, and an optimized structural model is determined according to the initial structural model.

Specifically, the heat exchanger can be composed of a shell, heat transfer pipes, a partition plate and the like, wherein the shell is round, parallel or spiral heat transfer pipes are arranged in the shell, and the heat transfer pipes are fixed on the shell. Two fluids which exchange heat in the heat exchanger, one fluid flows in the heat transfer tube, and the stroke of the fluid is called tube side; flow outside the tube, the travel of which is called the shell side. In this embodiment, the shell side is referred to as a one-circuit, and the tube side is referred to as a two-circuit.

The heat exchanger can be a vertical shell-and-tube baffled heat exchanger, the primary loop liquid lead bismuth alloy passes through the shell side from top to bottom at the inlet of the main heat exchanger, and the secondary loop feed water passes through the tube side from bottom to top at the secondary loop inlet. The heat exchanger transfers the heat of the liquid lead bismuth alloy of the coolant of the first loop to the water of the second loop, so that the water with higher temperature is generated and transferred to the outside.

The heat exchanger comprises a plurality of first heat transfer tubes in the initial structural model, and comprises a plurality of second heat transfer tubes in the optimized structural model, wherein the sum of the surface areas of the outer walls of the plurality of second heat transfer tubes is equal to the sum of the surface areas of the outer walls of the plurality of first heat transfer tubes, and the inner diameter of the second heat transfer tubes is larger than the inner diameter of the first heat transfer tubes. Because the number of the heat transfer tubes in the existing heat exchanger model is more than 421, and the detail size is smaller, for example, the tube wall thickness is only 1.5 mm, if the grid quality is ensured during grid division, the number of the grids is extremely large, so that operation and analysis cannot be performed on so many control bodies. Aiming at the problems of complex structure and small fine size of the model, the heat exchanger model is optimized in the embodiment, and the concrete steps are as follows:

On the premise of ensuring the constant heat exchange area of the primary loop, namely the constant contact area between the liquid lead bismuth alloy and the outer wall of the solid heat transfer tube, the number of the heat transfer tubes is reduced, and the number of the heat transfer tubes is adjusted from 421 heat transfer tubes to 7 heat transfer tubes; the arrangement mode is still in regular triangle arrangement, the inner diameter of the heat transfer tube is increased, the inner diameter of the heat transfer tube is adjusted from 22 mm to 190.88 mm, and the position and the size of the moon-shaped partition plate are kept unchanged. To ensure the accuracy of the stress analysis, the wall thickness of the heat transfer tube was kept constant at 1.5 mm. The schematic diagram of the optimized heat exchanger structure model is shown in fig. 2.

Step S104, dividing the optimized structure model to obtain a corresponding grid.

The optimized structure model can comprise a primary loop fluid flow channel model, a solid heat transfer tube model and a secondary loop fluid flow channel model. After the optimization of the structural model of the heat exchanger is completed, the primary loop fluid flow channel model, the solid heat transfer pipe model and the secondary loop fluid flow channel model are led into a modeling module of ANSYS Workbench, the physical properties of two fluid parts (namely the primary loop fluid flow channel model and the secondary loop fluid flow channel model) are defined as liquid (fluid), and the physical properties of a pipe wall part (namely the solid heat transfer pipe model) are defined as solid (solid). And then, dividing the adjusted optimized structure model by a grid module and a grid dividing method to obtain corresponding grids.

Finally, the obtained grid is subjected to grid independence analysis, and the check index can select the average temperature of a loop outlet and/or the flow speed in the Y direction (along the main flow direction) for check. When the number of meshes increases and the change in the check index is smaller than the threshold value (for example, 1%), the calculation result can be considered to be substantially irrelevant to the number of meshes, and the mesh corresponding to the number of meshes at this time is adopted as the mesh corresponding to the optimized structure model.

Step S106, determining simulation parameters corresponding to the working condition to be simulated of the heat exchanger.

Specifically, the working condition to be simulated comprises at least one of the following: steady-state operation working condition, main pump idle transient working condition, primary loop lost flow non-shutdown transient working condition; simulation parameters include, but are not limited to: and calculating fluid dynamics model setting parameters, material parameters corresponding to the heat exchanger, boundary condition parameters, simulation algorithm discrete format parameters and the like. Among other things, computational fluid dynamics (Computational Fluid Dynamics, CFD) models can perform simulation analysis of various hydrodynamic problems. The CFD model setting parameters are simulated basic parameters, and can comprise model precision, gravity direction, turbulence model parameters, standard wall surface conditions and the like; the material parameters comprise physical parameters of media in the first loop and the second loop, and can comprise density, dynamic viscosity, heat conductivity coefficient and the like; boundary condition parameters may include inlet boundary conditions, outlet boundary conditions, loop outer wall boundary conditions, heat transfer boundary conditions, etc.; the simulation algorithm discrete format parameters can comprise energy items, motion items, pressure items, gradient items, relaxation factors and the like, and specific simulation parameters can be set according to the working condition to be simulated.

Step S108, inputting the grid and the simulation parameters into a preset computational fluid dynamics model, and determining a simulation result of the working condition to be simulated.

Wherein the simulation result may include: a temperature field simulation result, a thermal stress field simulation result, a speed field simulation result, and the like. Specifically, the grid obtained by dividing the optimized structure model and the simulation parameters are input into a preset computational fluid dynamics model, namely a CFD model, so that the CFD model performs simulation calculation on the grid to obtain a simulation result. After the simulation result is converged, the simulation result can be analyzed. And when the simulation result is analyzed, a visual calculation result distribution diagram can be generated and displayed according to the simulation result of the working condition to be simulated, so that the distribution condition of each physical field in the heat exchanger can be observed systematically.

The embodiment of the application provides a simulation method of a heat exchanger, which comprises the steps of obtaining an optimized structure model by optimizing an initial structure model, wherein the sum of the surface areas of the outer walls of a heat transfer pipe of the optimized structure model is equal to the sum of the surface areas of the outer walls of the heat transfer pipe of the initial structure model, the inner diameter of the heat transfer pipe is larger than the inner diameter of the heat transfer pipe of the initial structure model, dividing the optimized structure model to obtain corresponding grids, determining simulation parameters corresponding to a working condition to be simulated of the heat exchanger, inputting the grids and the simulation parameters into a preset computational fluid dynamics model, and determining a simulation result of the working condition to be simulated, wherein the simulation result comprises at least one of the following steps: a temperature field simulation result, a thermal stress field simulation result and a speed field simulation result. The method realizes the simulation calculation of the working condition of the heat exchanger, can reduce the simulated calculated amount and improves the simulation effect of the heat exchanger.

Alternatively, in step S104, the step of dividing the optimized structure model into corresponding meshes may be performed in the following manner:

and A1, carrying out physical property classification adjustment on the primary loop fluid flow channel model, the solid heat transfer pipe model and the secondary loop fluid flow channel model to obtain an adjusted optimized structure model.

After the optimization of the structural model of the heat exchanger is completed, the primary loop fluid flow channel model, the solid heat transfer pipe model and the secondary loop fluid flow channel model are led into a modeling module of ANSYS Workbench, the physical properties of two fluid parts (namely the primary loop fluid flow channel model and the secondary loop fluid flow channel model) are defined as liquid (fluid), and the physical properties of a pipe wall part (namely the solid heat transfer pipe model) are defined as solid (solid), so that the adjusted optimized structural model is obtained.

And step A2, determining grid parameters of grid division. The grid parameters include, but are not limited to, connection attribute parameters that are used to eliminate the contact area between the fluid in one circuit and the fluid in two circuits, and to preserve the contact area between the fluid in one circuit and the outer wall of the second heat transfer tube and the contact area between the fluid in two circuits and the inner wall of the second heat transfer tube.

Specifically, in a mesh (sizing) module, since the tube wall thickness of the heat transfer tube is much smaller than the dimensions of the other components of the heat exchanger, the system automatically determines that there is direct contact between the primary and secondary loop fluids and creates a contact region. Without adjustment, FLUENT will default to interface the contact regions, and fluid from both circuits can flow through the interface to achieve intermixing. Thus, the connection attribute parameter in the grid module is adjusted, e.g. the tolerance is adjusted to 100, and the tolerance is adjusted to 10 ^-7 The magnitude of the contact area between the fluids of the two circuits after adjustment is eliminated, the lead bismuth alloy of one circuit and the second circuitThe contact areas of the outer wall surface of the heat transfer tube, the two-circuit water supply and the inner wall surface of the second heat transfer tube are still reserved for heat exchange in the subsequent step.

In addition, the parts of the primary loop, the secondary loop inlet and outlet, the heat exchange surface and the like are respectively selected and named and added to a named part (Name section) so as to conveniently specify boundary conditions in FLUENT software. In the setting of the grid parameters, the physical parameters (Physics preference) of the grid are adjusted to CFD, the solver parameters (Solver preference) select fluid (Fluent), the generation mode is adjusted to self-adaptation (Adaptive), and the system automatically selects the matching grid type. In addition, the cross angle center (span angle center) and the smooth (smoothing) are selected to be high in quality (fine), the transition is selected to be slow (slow), the correlation (release) is adjusted to be 100, so that the quality of the grid of the contact part between different parts (bodies) can be guaranteed to be good, and the cell size (element size) of the grid is finally set to be 0.02m. It should be noted that, each parameter of the above-mentioned grid may be adaptively adjusted according to an actual simulation condition.

And step A3, dividing the adjusted optimized structure model according to the grid parameters to obtain a corresponding grid.

Specifically, based on the optimized structure model after the grid parameter division and adjustment, a plurality of grids with the grid number of 1218065 and the node number of 684114 are generated, wherein the tetrahedral grids are generated by the first loop fluid flow channel due to irregular shapes, the hexahedral grids are generated by the solid heat transfer pipe and the second loop fluid flow channel due to regular-shaped cylinders and round tubes, and the maximum deviation (skewness) of the whole model is 0.938, so that the Fluent solving condition is met. Fig. 3 shows a grid schematic of the overall model of the heat exchanger, and fig. 4 shows a grid schematic of the bottom surface of the heat exchanger model.

After the grids are obtained, grid independence analysis can be performed, check indexes are checked by selecting the average temperature of a loop outlet and/or the flow speed in the Y direction (along the main flow direction), the number of grids can be adjusted by adjusting the unit size of the grids, 1000 steps are calculated when each grid is calculated, other boundary conditions are unchanged, and the unit size, the average temperature and the Y-direction flow speed corresponding to each grid are shown in table 1.

TABLE 1

From the analysis in table 1, it was found that the variation in the speed and temperature index at the outlet of the primary circuit was less than 1% when the mesh number was adjusted in the range of 121 to 703. Therefore, it is considered that the calculation result is substantially independent of the number of meshes when the number of meshes is 121 ten thousand or more. However, if the unit size is continuously increased, the grid number is continuously reduced, the grid quality is continuously reduced, and the basic requirement of the calculation of Fluent cannot be met, so that the grid number can be calculated by adopting 121 ten thousand of heat exchangers.

After the grid division and the grid independence analysis of the whole model are completed, the method enters Fluent software to start the digital simulation analysis of the 10MW power steady-state working condition. Because the CiADS has two main heat exchangers in total, the heat exchange quantity of a single heat exchanger is 5MW.

In practical application, since the heat exchanger model is complex as a whole, the control body is more, the factors influencing the flow and the heat transfer are more, but the actual influence of a plurality of single factors on the result is smaller, so the following assumption is made in the embodiment:

(1) In the heat exchanger, the liquid lead bismuth alloy and water are in a stable turbulence state, the flow and the heat transfer are not changed drastically, and the physical properties of the two-loop water supply are stable and phase change is not generated.

(2) The fluid is a newtonian fluid, isotropic and continuous throughout, with the fluid at the wall being in a slip-free boundary condition.

(3) The parameters such as density, specific heat capacity, heat transfer coefficient, kinematic viscosity and the like of the fluid only change along with the change of temperature, and are irrelevant to the parameters such as pressure, speed and the like. The heat exchange coefficient of the fluid and the wall surface is kept unchanged all the time in the whole heat exchange process.

(4) The junction of the fluid of the first circuit and the heat exchanger vessel, the moon-shaped partition plate and the like is set as an adiabatic condition, namely, only heat exchange between the two circuits exists.

(5) Gaps do not exist between the moon-shaped partition plates, the heat transfer tubes and the heat exchanger cylinder.

After the grids are determined, simulation parameters of the working conditions to be simulated are set, and the simulation parameters are specifically as follows:

(1) The basic parameters are calculated hydrodynamic model setting parameters. The Fluent software launch option is set to Double precision (Parallel). Selecting Pressure solver (Pressure base) in General setting, steady state (Steady), gravity direction set to point to negative direction of z coordinate axis, size-9.8 m/s ² . The Energy (Energy) model is turned on in the model setup, the turbulence option selection criteria k-epsilon model, standard k-epsilon, standard wall function, etc.

(2) Material parameters. Liquid lead bismuth alloy, liquid water under 5 megapascals pressure and 316TI stainless steel are added to the material parameters.

Because the density and viscosity of the 5Mpa sewage are obvious along with the temperature change, the physical property parameters of the 5Mpa sewage at each temperature can be detected through a physical property lookup table, then linear fitting is carried out, and the relationship between the physical property and the temperature of the water obtained after fitting is as follows:

density of water under 5Mpa pressure (kg/m) ³ ) The method comprises the following steps: ρ= -1.45939t+1563.3452; wherein T is the kinetic temperature, unit K. The density of the secondary water is 784.3137kg/m at a pressure of 5Mpa and a temperature of 533.15K (260℃) ³ 。

The dynamic viscosity (kg/mS) of water at 5MPa pressure is: mu= -3.42498 x 10 ^-4 T+0.31339; wherein T is the kinetic temperature, unit K. The dynamic viscosity of the secondary water was 0.131325 kg/mS at a pressure of 5MPa and a temperature of 533.15K (260 ℃).

Due to the optimization of the model, the inner diameter of the heat transfer tube is increased, if the original physical parameters are kept unchanged, the heat exchange capacity of the two loops is greatly reduced, and the simulation result shows that the difference between the fluid temperature on the central line and the boundary is very large at the outlet of the water of the two loops. This indicates that the heat transfer capacity of the secondary loop water is not matched with that of the primary loop, and the purpose of simulation analysis cannot be achieved. Based on the above, the target heat conductivity coefficient of the fluid in the two loops can be determined according to the optimized structural model and the heat conductivity coefficient of the fluid in the two loops; and the target heat conductivity coefficient is used as the heat conductivity coefficient of the fluid in the second loop, so that the accuracy of the simulation analysis of the heat exchanger is ensured.

In the embodiment, the following model is established to solve the problem of the heat conductivity coefficient of the two-loop water after analysis and correction. The problem is abstracted into a two-dimensional heat transfer model, in a rectangle with the bottom side length of 11 mm, water flow with the pressure of 5Mpa and the temperature of 225 ℃ flows in from the vertical bottom side at the speed of 1.31m/s, and under the steady state condition, the right temperature is T1, and the left temperature is T2. The heat exchange coefficient between the rectangular side and the water flow boundary is infinite, namely the temperature of the two boundaries of the water flow is also T1 and T2. At this time, the length of the bottom edge of the rectangle is adjusted to 95.44 mm, and other physical parameters of the water flow are unchanged except the heat conductivity coefficient, and the temperature of the two sides is still T1 and T2, so that the ratio of the new heat conductivity coefficient to the old heat conductivity coefficient is calculated.

The model is analyzed and assuming that there is no cross flow of liquid, the model can be analyzed with pure thermal conduction issues. The heat conduction problem can be described by fourier's law as:

φ＝-λA dt/dx (1)

wherein phi represents heat, lambda represents thermal conductivity, and A represents heat transfer area.

In this embodiment, the heat transferred into the two loops is used for the rise of the fluid temperature, so that the heat phi is proportional to the mass of the fluid and proportional to the square of the diameter. In a cylinder, take any infinitesimal small circle with a spacing dr, the heat transfer area should be proportional to the radius r, so the heat transfer area a is proportional to the diameter. Since the inlet and outlet temperature is unchanged and the temperature difference between the first loop and the second loop is unchanged, the dt is unchanged, and it is obvious that dx is directly proportional to the diameter. Therefore, under the condition of ensuring the consistent temperature difference between the inside and the outside, the heat conductivity coefficient lambda is in direct proportion to the square of the diameter, and the heat conductivity coefficient of water in the embodiment can be adjusted to 37.7697W/m.K.

(3) Boundary condition parameters

(1) Inlet boundary conditions;

the inlet boundary conditions were all set to velocity inlet (velocity-inlet), the inlet area of a loop was about 0.026 square meters, the inlet flow rate was 1.3134m/s, and the inlet gauge pressure was 0Pa. The inlet area of the second loop is about 0.026 square meter, the inlet flow rate is 1.3134m/s, and the inlet gauge pressure is 4.9MPa.

(2) Outlet boundary conditions;

the outlet boundary conditions were set to be pressure-outlet (pressure-outlet), the primary circuit outlet gauge pressure was 0Pa, and the secondary circuit outlet gauge pressure was 4.9MPa, i.e., the reduced pressure drop when fluid flowed through the flow channel was ignored.

(3) A loop outer wall boundary condition;

according to the assumption, the contact area of the primary heat exchanger outer wall and the moon-shaped partition plate of the primary heat exchanger is taken as an adiabatic boundary, the wall surface material is 316TI stainless steel, and the heat flux density is 0.

(4) Heat transfer boundary conditions;

after importing the model and mesh into Fluent, the software automatically recognizes the contact region (contact region) and generates an interface region accordingly. Each interface will create four walls. For example, in the contact area between the secondary water and the inner wall of the solid heat transfer tube, the generated wall-95 represents the boundary heat transfer wall surface of the runner of the secondary water, the wall-96 represents the inner wall surface of the solid heat transfer tube, and the generated wall-94 and wall-94-shadow represent the interface of the contact area. After setting the wall-95 and wall-96 wall-materials to 316TI, the Momentum (Momentum) condition is fixed (stationary), no slip (no slip) and given the heat exchange coefficient, the wall-94 and wall-94-shadow wall-materials to 316TI stainless steel, and the wall-type to coupling (Coupled), heat can flow out from the inner wall surface of the solid heat transfer tube through the interface and into the two-circuit fluid.

The heat exchange coefficient between the fluid and the solid wall is given by an empirical formula. For a loop fluid, the flow model is a fluid sweep fork bank bundle convective heat transfer model. In this embodiment a loop reynolds number re=1.264×10 ⁶ The characteristic length is taken into the diameter of the circular tube of the inlet, and the flow velocity is correspondingly selected from the flow velocity of the inlet. In the embodiment, the average value of the average temperature of the inlet and the outlet of the loop is taken as the average value of the temperature of the liquid lead-bismuth alloy in the whole system, and the loop lead-bismuth alloy Knoop is calculated629.95, thus obtaining a heat exchange coefficient of 39877.925W/m between the fluid and the solid wall surface of the loop ² ·K。

For the two-circuit fluid, the flow model is a forced convection heat exchange model with turbulence heated in a circular tube. For this model, the most common is the Dittus-Boelter formula:

N _uf ＝0.023Re _f ^0.8 Pr _f ^0.4 (2)

wherein N is _u Denote Nusselt numbers, re denotes Reynolds numbers, pr denotes Prandtl numbers, and subscript f denotes fluids.

In this embodiment, the average temperature of the inlet and outlet of the two loops is taken as the average temperature of the water supply of the two loops in the whole system, the characteristic length is selected from the inner diameter of the heat transfer tube of the two loops, the flow velocity is 0.1846m/s of the inlet flow velocity of the two loops, and the Reynolds number Re= 2.55349 X10 of the water of the two loops is obtained ⁵ Substituting the above formula to calculate the two-circuit Bernoulli number as 460.5143. Therefore, the heat exchange coefficient of the secondary water and the inner wall of the solid heat transfer tube is 96630W/m ² ·K。

(4) Algorithm discrete format parameters

In this embodiment, a calculation method SIMPLE (Semi-implicit method of the pressure coupling equation set) algorithm is selected. The SIMPLE algorithm first assumes an initial velocity field and a pressure field, then solves a discrete form of the navier-stokes equation, correcting the pressure and velocity. And then solving other equations, and carrying out the next calculation after the convergence of the result. In terms of discrete format, energy (Energy) and Momentum (Momentum) terms select a Second Order windward format (Second Order Upwind), the Second Order format is more accurate than the first Order format, turbulence parameters (Turbulent Kinetic Energy, turbulent Dissipation Rate) select a first Order windward format (First Order Upwind), the first Order format converges faster than the Second Order format, pressure (presure) terms select a Second Order method, gradient term selection is based on the least squares method of the unit cells (Least Squares Cell Based), and the relaxation factor is set to 0.25.

(5) Initializing and calculating parameters

Specifically, the number of calculation steps (Iterations) may be used to select 1000 steps using the hybrid initialization condition (Hybrid Initialization).

After the calculation is completed, whether the simulation result is converged or not may be judged, optionally, in step S108, the grid and the simulation parameters are input into a preset computational fluid dynamics model, and the simulation result of the working condition to be simulated is determined, including: inputting the grid and the simulation parameters into a preset computational fluid dynamics model, and performing simulation calculation on the grid to obtain a calculation result; determining an inlet and outlet flow difference value of a first loop and an inlet and outlet flow difference value of a second loop; judging whether the inlet and outlet flow difference values of the first loop and the second loop are smaller than a flow difference value threshold value or not, and whether the residual error of the simulation parameter is smaller than a convergence threshold value or not; if yes, determining the calculation result as a simulation result of the working condition to be simulated; otherwise, the calculation steps are increased until the inlet and outlet flow difference value of the first loop and the inlet and outlet flow difference value of the second loop are smaller than the flow difference value threshold value, and the residual error of the simulation parameters is smaller than the convergence threshold value.

For example, after analog computation, the residuals of each parameter are reduced to 10 ^-3 Magnitude, accounting for the calculation has converged substantially; and checking the inlet and outlet flow difference, wherein the first loop flow difference is-0.08 kg/s, the second loop flow difference is-0.0016 kg/s, and the ratio of the two loop flow differences to the total flow is respectively 0.022% and 0.0053%, which are both less than 0.1%. The combination of the two conditions can illustrate that the calculation result converges, and at this time, the calculation result can be determined as a simulation result of the working condition to be simulated.

And simulating to obtain a loop overall temperature result, a two-loop overall temperature result, a loop inlet section temperature result, an outlet section temperature result and the like under the 10MW steady-state working condition. Wherein the liquid lead bismuth alloy of the first circuit mainly flows downwards after entering from the inlet and is rapidly cooled by the second circuit. The flow is in a path similar to an S shape by bypassing the crescent-shaped partition plate in the flowing process, and the flow is fully contacted with the two loops. Overall, the temperature decreases from the inlet to the lower. The primary circuit is at a high temperature in the upper part of the primary heat exchanger, in particular in the inlet part, and a large temperature difference with the secondary circuit is formed, and the coolant is cooled very quickly. Along with the continuous decrease of the temperature of the liquid lead-bismuth alloy, the temperature difference is reduced, the cooled speed is gradually slowed down, and the temperature change of the lower part of the whole main heat exchanger is smaller.

There is a large difference between the temperature changes of the heat transfer tubes in the two loops, especially the heat transfer tube closest to the inlet, the liquid lead bismuth alloy around it has the highest temperature, the heat transfer amount is also the highest, and the outlet temperature is also the highest, consistent with theory. The average temperature of the outlet of the first loop is 555.7448K, which is 2.5948K lower than the theoretical temperature 553.15K, the actual temperature reduction is 2.6% lower than the theoretical value, the average temperature of the outlet of the second loop is 529.1935K, which is 3.9565K lower than the theoretical temperature 533.15K, and the actual temperature increase is 11.3% lower than the theoretical value. The above deviation is within an acceptable range, and the calculation result has a reference value.

In addition, the speed results of the inlet section, the outlet section and the main flow direction of the loop are obtained through simulation under the 10MW steady-state working condition. The speed distribution of the inlet section and the outlet section of the steady-state working condition is basically continuous, and a few parts with abrupt speed change trend mainly comprise: the inlet lead bismuth alloy flows into a flow field similar to jet impact generated when the inlet lead bismuth alloy collides with a heat transfer tube; there is a partial reflux at the outlet. The two conditions have no great influence on the whole flow, and the flow field in the model can be completely considered to be stable, and the phenomenon of flow instability does not exist.

Further, after CFD simulation calculation is completed in Fluent, the calculated result is led into a static structure (Static Structural) module for thermal stress analysis, and equivalent stress analysis can be carried out on each second heat transfer tube according to the temperature field simulation result, so that a thermal stress field simulation result is obtained.

In particular, in a static structural module, the above-described similar treatment is applied to the automatically identified contact areas, reducing the tolerance ranges to avoid direct contact of the two circuit fluids. The physical parameters are then set to Mechanical (Mechanical). Since the temperature field is already derived during CFD, the requirements on the grid accuracy at the time of stress analysis are relatively low. The generation mode and the grid size selected in this embodiment select default settings, and directly generate grids, where the number of grids is 529967.

After grid generation is completed, the solid wall temperature results calculated in Fluent are imported, the models of seven solid heat transfer tubes are selected one by one before importing, and then the models are corresponding to the temperature fields calculated by CFD results. In the temperature distribution on the solid wall, the upper temperature of the main heat exchanger is higher, the maximum value exists near the inlet, and the lower temperature is lower. After the temperature is introduced, solving the thermal stress of the seven heat transfer tubes to obtain an equivalent stress simulation result.

In the heat transfer tube thermal stress simulation result, the maximum value of the thermal stress is 9.42 multiplied by 10 ⁸ Pa, which is present near the flow field of the jet generated at the inlet of a circuit, is not the initial point of contact of the circuit fluid with the heat transfer tube at the inlet. The reason that the thermal stress at the contact point is not the maximum is that the thermal stress is only related to the temperature difference, the solid wall surface is positioned in the stagnation area of the jet flow field, the local heat transfer intensity is the highest, the heat transfer process is the most smooth, and therefore the temperature of the wall surface of the heat transfer tube is not the highest, and the thermal stress is slightly smaller than the surrounding. In general, the upper part of the heat transfer tube has larger thermal stress due to the higher temperature of the lead-bismuth alloy of the first circuit and the larger temperature difference between the inner wall and the outer wall, and the lower part of the heat transfer tube has smaller temperature difference between the lead-bismuth alloy of the first circuit and the inner wall and the outer wall, and therefore, the thermal stress is smaller, and the difference between the maximum thermal stress and the minimum thermal stress is an order of magnitude.

The yield strength of the 316TI stainless steel is 310MPa, the allowable stress is 1.5 times of that of the stainless steel, at least 465MPa, but still less than the maximum 942MPa obtained by solving, so that the design of the solid heat transfer tube with the wall thickness of 1.5 mm has potential safety hazards, and a break accident is likely to occur in the heat transfer process. Thus, the material with larger allowable stress can be used as the material of the heat transfer tube by increasing the thickness of the wall of the solid heat transfer tube.

In this embodiment, two transient conditions are also simulated, including a main pump idle transient condition and a loop no-current shutdown transient condition.

The simulation process of the idle transient working condition of the main pump is as follows:

the idle transient working condition of the main pump refers to that under the condition that the main pump stops running, the reactor core is shut down, the flow of the lead-bismuth alloy is maintained by a loop only depending on the natural circulation capacity, the related data of the initial condition is obtained by simulation of an ATHLET (Analysis of Thermal-Hydraulics of Leaks and Transients) system analysis program, and the calculated data of the system analysis program is fitted to obtain an expression of the change of the inlet temperature and the flow rate along with the time. The model was set to transient, the inlet temperature and flow rate in boundary conditions were given by udf (user defined function) function, specifying generation of a graph of loop outlet temperature versus time. The time step was set to 0.01s and the total number of time steps was set to 300000 steps for calculation.

Specifically, a total of 83000 time steps are calculated for this operating condition, for a total of 830 seconds. Under the idle transient working condition of the main pump, referring to a schematic diagram of a simulation result of the average temperature of the outlet of the first loop shown in fig. 5, a curve of the average temperature of the outlet of the first loop under the idle transient working condition of the main pump is shown. Wherein, the abscissa is the current time (flow-time), the ordinate is the weighted average temperature of a loop Area (Area-Weighted Average of temperature 1), and when the inlet temperature is reduced to 629K, the outlet temperature is reduced from 555K to 548K, and the reduction range is about 8K. After falling to around 548K, the stability does not drop. The second loop outlet temperature also drops from 529K to around 507K.

The simulation process of the transient condition of the loop without shutdown due to current loss is as follows:

the working condition of no shutdown of the primary pump during the primary loop current loss refers to the condition that the primary pump is in power failure, shaft breakage or shaft clamping and other electrical or mechanical problems occur in the primary loop system, the primary pump cannot accelerate liquid at the moment, the whole primary loop completely maintains the flow of liquid lead bismuth alloy coolant by natural circulation capacity, the flow of the coolant is reduced at the moment, but the reactor core part cannot take effective protection measures, and full-power operation is still maintained. The initial condition related data of the transient condition of the loop current loss and no shutdown is obtained by calculation and simulation of an ATHLET system analysis program, and the data calculated by the system analysis program is fitted to obtain an expression of time variation of inlet temperature and flow rate. The model was set to transient, the inlet temperature and flow rate in boundary conditions were given by udf (user defined function) function, specifying generation of a graph of loop outlet temperature versus time. The time step is set to 0.01s and the total number of time steps is set to 10000 steps for calculation.

Specifically, this operating mode calculates 10000 time steps in total, which amounts to 100 seconds.

Under the loop-lost-flow non-shutdown working condition, referring to a schematic diagram of a loop-exit average temperature simulation result shown in fig. 6, a loop-exit average temperature change curve of a loop-lost-flow non-shutdown transient working condition is shown, referring to a schematic diagram of a loop-exit average temperature simulation result shown in fig. 7, a loop-exit average temperature change curve of a loop-lost-flow non-shutdown transient working condition is shown. In fig. 6 and 7, the current time is plotted on the abscissa, and the area weighted average temperatures of the first loop and the second loop are plotted on the ordinate. It can be seen that after a loop loss of flow does not shut down for 100 seconds, in the case that the temperature of the inlet of the loop rises to 667K, the temperature of the outlet of the loop is reduced instead from 555K to a minimum of about 547.5K, and then fluctuates, finally reaching about 549K, and the reduction amplitude is about 6K. The second loop outlet temperature also correspondingly decreased from 529K to a minimum of about 510K, and then increased back again, with the first loop outlet temperature decreasing by about 18K at about 511K for 100 seconds.

In the transient working condition that the primary loop loses flow and does not stop, the flow of the coolant is reduced, the heat produced by the reactor core is not changed, the temperature of the outlet of the pressure vessel is increased, and the temperature of the inlet of the primary loop of the primary heat exchanger is also obviously increased. However, since the two-circuit structure and function are not destroyed, the cooling capacity is improved compared with the steady state due to the increase of the temperature difference, the decrease of the inlet flow of the coolant of the other circuit is more dominant compared with the increase of the inlet temperature, so that the total energy input into the heat exchanger of the one circuit is actually decreased, and the change trend of the outlet temperature of the next circuit is decreased when the two-circuit structure and function are completely cooled. The heat input by the first circuit is reduced, so that the heat absorbed by water can be reduced, and the temperature rise is reduced naturally to reduce the outlet temperature under the condition that the inlet temperature of the second circuit is unchanged.

Therefore, under the transient working condition that the primary loop loses current and does not stop, the primary loop heat exchanger part does not have serious potential safety hazards, the part with obviously raised temperature is still concentrated in the pressure vessel, and the main problem is that the temperature in the reactor core cannot be effectively taken away and the temperature of the reactor core is raised. However, because of the natural circulation capacity inherent in the lead-based fast reactor, the coolant flow rate does not drop to 0, but is maintained at a high flow rate level, and the lead-bismuth alloy as the coolant has a low melting point and an extremely high boiling point, it is difficult to occur a phenomenon that a large amount of coolant water is gasified, which may occur in the pressurized water reactor, and the core temperature is finally maintained at a value higher than the transient level but maintained within a safe range.

In summary, the design temperature of the CiADS system under the 10MW power steady state condition is substantially consistent with the simulation result, but the thermal stress exceeds the maximum allowable stress value permitted by the material, and there is a risk of occurrence of heat transfer tube breach accidents. In the transient simulation of the model, the transient working condition of idle shutdown of a main pump and the transient working condition of no shutdown of loop current loss are mainly simulated. In the two working conditions, under the condition that the two loop structures and the cooling function are kept to be completed, the reduction of the flow of the coolant of the first loop has important influence on the whole transient working condition, and the average temperature of the outlet of the first loop is correspondingly reduced, so that the conclusion can be drawn that under the transient working condition that the flow of the two first loops is greatly reduced, the structures and the functions of the main heat exchanger still keep better, and compared with a steady state, no additional accident risk exists.

In summary, particular embodiments of the present subject matter have been described. Other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may be advantageous.

The above simulation method for the heat exchanger provided by the embodiment of the application is based on the same thought, and the embodiment of the application also provides a simulation device for the heat exchanger.

Fig. 8 is a schematic structural view of a simulation device of a heat exchanger according to an embodiment of the present application. Referring to fig. 8, in a software implementation, the simulation device of the heat exchanger may include: a model determining module 81, a meshing module 82, a parameter determining module 83 and a simulation result determining module 84, wherein the functions of the respective modules are as follows:

the model determining module 81 is configured to obtain an initial structural model of the heat exchanger, and determine an optimized structural model according to the initial structural model; the heat exchanger comprises a first loop and a second loop for heat exchange; the initial structural model comprises a plurality of first heat transfer pipes, the optimized structural model comprises a plurality of second heat transfer pipes, the sum of the outer wall surface areas of the plurality of second heat transfer pipes is equal to the sum of the outer wall surface areas of the plurality of first heat transfer pipes, and the inner diameter of the second heat transfer pipes is larger than the inner diameter of the first heat transfer pipes;

a grid dividing module 82, configured to divide the optimized structure model to obtain a corresponding grid; the optimized structure model comprises a primary loop fluid flow channel model, a solid heat transfer pipe model and a secondary loop fluid flow channel model;

The parameter determining module 83 is configured to determine a simulation parameter corresponding to a to-be-simulated condition of the heat exchanger; the simulation parameters include at least one of: calculating a fluid dynamic model setting parameter, a material parameter corresponding to the heat exchanger and a boundary condition parameter;

the simulation result determining module 84 is configured to input the grid and the simulation parameters into a preset computational fluid dynamics model, and determine a simulation result of the to-be-simulated working condition; the simulation result comprises at least one of the following: a temperature field simulation result, a thermal stress field simulation result and a speed field simulation result.

In one embodiment, the meshing module 82 is specifically configured to:

performing physical property classification adjustment on the primary loop fluid flow channel model, the solid heat transfer pipe model and the secondary loop fluid flow channel model to obtain an adjusted optimized structure model;

determining grid parameters of grid division; the grid parameters comprise connection attribute parameters, wherein the connection attribute parameters are used for eliminating a contact area between the fluid in the first loop and the fluid in the second loop, and reserving a contact area between the fluid in the first loop and the outer wall of the second heat transfer tube and a contact area between the fluid in the second loop and the inner wall of the second heat transfer tube;

And dividing the adjusted optimized structure model according to the grid parameters to obtain corresponding grids.

In one embodiment, the parameter determining module 83 is specifically configured to:

determining a target heat conductivity coefficient of the fluid in the two loops according to the optimized structure model and the heat conductivity coefficient of the fluid in the two loops;

and taking the target heat conductivity coefficient as the heat conductivity coefficient of the fluid in the two loops.

In one embodiment, the simulation result determining module 84 is specifically configured to:

inputting the grid and the simulation parameters into a preset computational fluid dynamics model, and performing simulation calculation on the grid to obtain a calculation result;

determining the inlet and outlet flow difference value of the first loop and the inlet and outlet flow difference value of the second loop;

judging whether the inlet and outlet flow difference values of the first loop and the inlet and outlet flow difference values of the second loop are smaller than a flow difference value threshold value or not, and whether the residual error of the simulation parameter is smaller than a convergence threshold value or not;

if yes, determining the calculation result as a simulation result of the working condition to be simulated.

and carrying out equivalent stress analysis on a plurality of second heat transfer tubes according to the temperature field simulation result to obtain the thermal stress field simulation result.

In one embodiment, the display module is further configured to:

and generating and displaying a visual simulation result distribution diagram according to the simulation result of the working condition to be simulated.

It should be understood by those skilled in the art that the simulation apparatus of the heat exchanger in fig. 8 can be used to implement the simulation method of the heat exchanger described above, and the detailed description thereof should be similar to that of the method section described above, so as to avoid complexity and avoid redundancy.

Based on the same thought, the embodiment of the application also provides simulation equipment of the heat exchanger, as shown in fig. 9. The analog devices of the heat exchanger may vary widely due to configuration or performance, and may include one or more processors 901 and a memory 902, where the memory 902 may store one or more stored applications or data. Wherein the memory 902 may be transient storage or persistent storage. The application program stored in the memory 902 may include one or more modules (not shown in the figures), each of which may include a series of computer executable instructions in an analog device for a heat exchanger. Still further, the processor 901 may be arranged to communicate with the memory 902 and execute a series of computer executable instructions in the memory 902 on an analog device of the heat exchanger. The analog devices of the heat exchanger may also include one or more power supplies 903, one or more wired or wireless network interfaces 904, one or more input/output interfaces 905, and one or more keyboards 906.

In particular, in this embodiment, the simulation device of the heat exchanger includes a memory, and one or more programs, where the one or more programs are stored in the memory, and the one or more programs may include one or more modules, and each module may include a series of computer-executable instructions in the simulation device of the heat exchanger, and configured to be executed by the one or more processors, the one or more programs including a simulation method for performing the heat exchanger.

Based on the same idea, the embodiment of the application also provides a storage medium for storing computer executable instructions, wherein the executable instructions realize the simulation method of the heat exchanger when being executed.

The system, apparatus, module or unit set forth in the above embodiments may be implemented in particular by a computer chip or entity, or by a product having a certain function. One typical implementation is a computer. In particular, the computer may be, for example, a personal computer, a laptop computer, a cellular telephone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

For convenience of description, the above devices are described as being functionally divided into various units, respectively. Of course, the functions of each element may be implemented in the same piece or pieces of software and/or hardware when implementing the present application.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In one typical configuration, a computing device includes one or more processors (CPUs, central Processing Unit), input/output interfaces, network interfaces, and memory. The Memory may include non-volatile Memory in a computer-readable medium, random access Memory (RAM, random Access Memory), and/or non-volatile Memory, such as Read-Only Memory (ROM) or flash RAM. Memory is an example of computer-readable media.

Computer readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of storage media for a computer include, but are not limited to, phase-change memory (PRAM, phase-Change Random Access Memory), static random access memory (SRAM, static Random Access Memory), dynamic random access memory (DRAM, dynamic Random Access Memory), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically erasable programmable read only memory (EEPROM, electrically Erasable Programmable Read Only Memory), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital versatile disks (DVD, digital Video Disc) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium, which can be used to store information that can be accessed by the computing device. Computer-readable media, as defined herein, does not include transitory computer-readable media (transmission media), such as modulated data signals and carrier waves.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.

The application may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The application may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.

In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, as relevant to see a section of the description of method embodiments.

The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the application are to be included in the scope of the claims of the present application.

Claims

1. A method of simulating a heat exchanger, comprising:

acquiring an initial structural model of the heat exchanger, and determining an optimized structural model according to the initial structural model; the heat exchanger comprises a first loop and a second loop for heat exchange; the initial structural model comprises a plurality of first heat transfer pipes, the optimized structural model comprises a plurality of second heat transfer pipes, the sum of the outer wall surface areas of the plurality of second heat transfer pipes is equal to the sum of the outer wall surface areas of the plurality of first heat transfer pipes, and the inner diameter of the second heat transfer pipes is larger than the inner diameter of the first heat transfer pipes;

Dividing the optimized structure model to obtain a corresponding grid; the optimized structure model comprises a primary loop fluid flow channel model, a solid heat transfer pipe model and a secondary loop fluid flow channel model;

determining simulation parameters corresponding to the working conditions to be simulated of the heat exchanger; the simulation parameters include at least one of: calculating a fluid dynamic model setting parameter, a material parameter corresponding to the heat exchanger and a boundary condition parameter;

inputting the grid and the simulation parameters into a preset computational fluid dynamics model, and determining a simulation result of the working condition to be simulated; the simulation result comprises at least one of the following: a temperature field simulation result, a thermal stress field simulation result and a speed field simulation result.

2. The method of claim 1, wherein the partitioning the optimized structure model into corresponding grids comprises:

3. The method of claim 1, wherein determining the simulation parameters corresponding to the to-be-simulated condition of the heat exchanger comprises:

4. The method of claim 1, wherein the inputting the grid and the simulation parameters into a preset computational fluid dynamics model to determine the simulation result of the to-be-simulated condition comprises:

5. The method of claim 1, wherein the inputting the grid and the simulation parameters into a preset computational fluid dynamics model to determine the simulation result of the to-be-simulated condition comprises:

6. The method of any one of claims 1-5, further comprising:

7. A simulator for a heat exchanger, comprising:

the model determining module is used for obtaining an initial structure model of the heat exchanger and determining an optimized structure model according to the initial structure model; the heat exchanger comprises a first loop and a second loop for heat exchange; the initial structural model comprises a plurality of first heat transfer pipes, the optimized structural model comprises a plurality of second heat transfer pipes, the sum of the outer wall surface areas of the plurality of second heat transfer pipes is equal to the sum of the outer wall surface areas of the plurality of first heat transfer pipes, and the inner diameter of the second heat transfer pipes is larger than the inner diameter of the first heat transfer pipes;

The grid dividing module is used for dividing the optimized structure model to obtain corresponding grids; the optimized structure model comprises a primary loop fluid flow channel model, a solid heat transfer pipe model and a secondary loop fluid flow channel model;

the parameter determining module is used for determining simulation parameters corresponding to the working conditions to be simulated of the heat exchanger; the simulation parameters include at least one of: calculating a fluid dynamic model setting parameter, a material parameter corresponding to the heat exchanger and a boundary condition parameter;

the simulation result determining module is used for inputting the grid and the simulation parameters into a preset computational fluid dynamics model and determining a simulation result of the working condition to be simulated; the simulation result comprises at least one of the following: a temperature field simulation result, a thermal stress field simulation result and a speed field simulation result.

8. The apparatus of claim 7, wherein the meshing module is specifically configured to:

9. A simulation apparatus of a heat exchanger, comprising:

a processor; and a memory arranged to store computer executable instructions that, when executed, cause the processor to implement the simulation method of a heat exchanger of any of claims 1-6.

10. A storage medium storing computer executable instructions which when executed implement the method of simulating a heat exchanger of any one of claims 1-6.