Method and device for determining heat transfer correlation of wire winding positioning fuel assembly

Abstract

The invention relates to the field of thermal hydraulic characteristic analysis of fuel assemblies, in particular to a method and device for determining a heat transfer correlation formula of a wire winding positioning fuel assembly, and the method comprises the steps: coupling a wire winding assembly model with a light rod bundle assembly model, and constructing a wire winding positioning fuel assembly model; based on the wire winding positioning fuel assembly model, a first average convective heat transfer coefficient under the preset physical working condition is obtained; according to the first average convective heat transfer coefficient and a second average convective heat transfer coefficient of the light rod bundle assembly model under the preset physical working condition, a correction factor is obtained through calculation; and according to the correction factor and a first heat transfer correlation formula corresponding to the light rod bundle assembly model, calculating to obtain a second heat transfer correlation formula corresponding to the wire winding positioning fuel assembly model. According to the method, the thermal hydraulic characteristics of the wire winding positioning fuel assembly are accurately analyzed, and the heat transfer correlation formula, namely the second heat transfer correlation formula, of the wire winding positioning fuel assembly is determined.

Description

Technical Field

[0001] The invention relates to the field of thermal hydraulic characteristic analysis of fuel assemblies, and in particular to a method and device for determining a heat transfer correlation equation of a wire winding positioning fuel assembly. Background Art

[0002] Due to the effects of coolant flow vibration, long-term irradiation, fission gas release and thermal swelling of pellets, fuel rods may suffer from dislocation and fatigue failure during long-term reactor operation, which may lead to serious consequences. In order to solve this problem, spiral metal wires can be fixed on the surface of the fuel rods to fix the fuel rod bundle. However, the introduction of wire winding also brings problems in heat transfer.

[0003] Compared with ordinary pressurized water reactors, supercritical water-cooled reactor assemblies have additional moderation channels. The coolant needs to take away more energy after flowing through the fuel assembly, and the physical properties of supercritical water as a coolant will change dramatically near the pseudo-critical line. These characteristics cause strong non-uniformity in the heat transfer of sub-channels in supercritical water-cooled reactor fuel assemblies. However, the introduction of spiral winding makes the flow field and temperature field near the fuel rods and the physical property changes of supercritical water more complicated, changing the heat exchange process between the fuel rods and the coolant. The winding structure is highly asymmetric relative to the fuel rods, and this asymmetry is also reflected in the changes in the flow field and temperature field of the fuel assembly after winding. This will cause the thermal-hydraulic characteristics of the wire-wound positioning fuel assembly to have strong non-uniformity, and may even cause the supercritical water to cross the pseudo-critical point and undergo drastic physical property changes. Therefore, unreasonable winding design may bring the risk of local failure of the fuel rods.

[0004] Since the supercritical water reactor is one of the fourth generation reactor types, the research is still in the exploratory stage. The research on supercritical water reactor fuel assemblies mostly stays at the bare rod stage, and there is little research on the thermal hydraulic characteristics of wire-wound fuel assemblies. Due to the difficulties in realizing and measuring the rod bundle experiment under transcritical conditions, numerical simulation methods are currently used to study the thermal hydraulic characteristics of fuel assemblies; in addition, current research and analysis are mostly focused on the thermal hydraulic characteristics of smooth fuel rod bundle assemblies above the pseudo-critical point. Therefore, there is still a lack of analysis on the wire-wound fuel rod bundle assemblies under transcritical conditions, and it is difficult to accurately analyze the thermal hydraulic characteristics of the wire-wound fuel assembly and obtain the corresponding heat transfer correlation. Summary of the invention

[0005] The purpose of the present invention is to provide a method and device for determining the heat transfer correlation equation of a wire-wound fuel assembly, so as to solve the problem that the prior art cannot accurately analyze the thermal-hydraulic characteristics of the wire-wound fuel assembly and determine the corresponding heat transfer correlation equation.

[0006] An embodiment of the present invention provides a method for determining a heat transfer correlation equation of a wire-wound fuel assembly, the method comprising the following steps: coupling a wire-wound assembly model with a light-rod bundle assembly model to construct a wire-wound fuel assembly model; based on the wire-wound fuel assembly model, obtaining a first average convective heat transfer coefficient under a preset physical condition; calculating a correction factor based on the first average convective heat transfer coefficient and a second average convective heat transfer coefficient of the light-rod bundle assembly model under the preset physical condition; calculating a second heat transfer correlation equation corresponding to the wire-wound fuel assembly model under the preset physical condition based on the correction factor and the first heat transfer correlation equation corresponding to the light-rod bundle assembly model under the preset physical condition.

[0007] Optionally, based on the wire winding fuel assembly model, obtaining the first average convective heat transfer coefficient under preset physical conditions, includes: based on the preset physical conditions, setting the initial conditions and boundary conditions of the wire winding fuel assembly model; wherein the initial conditions are the pressure field and temperature field of the fluid channel, the temperature field of the rod bundle and the temperature field of the wire winding, and the boundary conditions are the fluid inlet and outlet boundary positions, and the flow rate and temperature corresponding to the fluid inlet and outlet boundary positions; based on computational fluid dynamics, calculating the first physical parameters of the wire winding fuel assembly model under the preset physical conditions; according to the first physical parameters and the first average convective heat transfer coefficient calculation formula, calculating the first average convective heat transfer coefficient.

[0008] Optionally, the first physical parameter includes a first heat flux density and a first temperature difference, wherein the first temperature difference is the temperature difference between the average temperature of the light rod surface and the wire winding surface and the mainstream temperature of the supercritical water; The first average convective heat transfer coefficient is calculated as follows: , , in, For coordinates The corresponding first convection heat transfer coefficient is, For coordinates The corresponding first heat flux density is, For coordinates The corresponding first temperature difference is is the first average convective heat transfer coefficient, is the length of the light rod bundle.

[0009] Optionally, the calculating the correction factor according to the first average convection heat transfer coefficient and the second average convection heat transfer coefficient of the optical rod bundle assembly model under the preset physical working condition comprises: performing a ratio operation on the first average convection heat transfer coefficient and the second average convection heat transfer coefficient of the optical rod bundle assembly model to obtain the correction factor; The calculation formula corresponding to the correction factor is as follows: , in, is the correction factor, is the first average convective heat transfer coefficient, is the second average convective heat transfer coefficient.

[0010] Optionally, the calculating, according to the correction factor and the first heat transfer correlation formula corresponding to the optical rod bundle assembly model under the preset physical working condition, a second heat transfer correlation formula corresponding to the wire winding positioning fuel assembly model under the preset physical working condition comprises: performing a product operation on the correction factor and the first heat transfer correlation formula corresponding to the optical rod bundle assembly model to obtain the second heat transfer correlation formula; The second heat transfer correlation is as follows: , in, For coordinates The corresponding first Nusselt number is, For coordinates The corresponding second Nusselt number is, is the correction factor, For coordinates The corresponding Reynolds number is, is the Prandtl number, is the density of supercritical water in the mainstream area, represents the density of supercritical water near the wall, is the flow channel diameter.

[0011] Optionally, the method also includes: establishing an initial optical rod bundle assembly model according to the optical rod bundle structure parameters and material property parameters; calculating the third average convection heat transfer coefficient under the preset physical working condition according to the first heat transfer correlation equation and the standard average convection heat transfer coefficient calculation formula; wherein the third average convection heat transfer coefficient is the standard average convection heat transfer coefficient corresponding to the optical rod bundle assembly model; obtaining the fourth average convection heat transfer coefficient under the preset physical working condition based on the initial optical rod bundle assembly model; judging whether the relative error between the third average convection heat transfer coefficient and the fourth average convection heat transfer coefficient is less than a preset error; if not, adjusting the grid size and time step of the initial optical rod bundle assembly model until the preset error is met; if so, determining the fourth average convection heat transfer coefficient as the second average convection heat transfer coefficient; and constructing the optical rod bundle assembly model according to the finally determined grid size and time step.

[0012] Optionally, obtaining the fourth average convective heat transfer coefficient under the preset physical conditions based on the initial optical rod bundle assembly model includes: setting the initial conditions and boundary conditions of the wire winding positioning fuel assembly model based on the preset physical conditions; wherein the initial conditions are the pressure field and temperature field of the fluid channel, and the temperature field of the rod bundle, and the boundary conditions are the fluid inlet and outlet boundary positions, and the flow rate and temperature corresponding to the fluid inlet and outlet boundary positions; based on computational fluid dynamics, calculating the second physical parameter of the wire winding positioning fuel assembly model under the preset physical conditions; and calculating the fourth average convective heat transfer coefficient according to the second physical parameter and the second average convective heat transfer coefficient calculation formula.

[0013] Optionally, the second physical parameter includes a second heat flux density and a second temperature difference, wherein the second temperature difference is the temperature difference between the average temperature of the light rod surface and the mainstream temperature of the supercritical water; The second average convective heat transfer coefficient is calculated as follows: , , in, For coordinates The corresponding second convection heat transfer coefficient is, For coordinates The corresponding second heat flux density is, For coordinates The corresponding second temperature difference is, is the fourth average convective heat transfer coefficient, is the length of the light rod bundle.

[0014] Optionally, the method also includes: determining the correction factor and the second heat transfer correlation equation corresponding to different preset physical conditions based on the wire winding fuel assembly model under different preset physical conditions; and preparing a correction factor table corresponding to the wire winding fuel assembly based on the correction factor and the second heat transfer correlation equation corresponding to different preset physical conditions; wherein the preset physical conditions include a preset temperature and a preset pressure.

[0015] The method for determining the heat transfer correlation of a wire-wound fuel assembly provided by the present invention has the following beneficial effects: A method for determining a heat transfer correlation equation of a wire-wound fuel assembly provided by an embodiment of the present invention is to construct a wire-wound fuel assembly model by coupling a wire-wound fuel assembly model with an optical rod bundle assembly model; based on the wire-wound fuel assembly model, a first average convection heat transfer coefficient under a preset physical condition is obtained; a correction factor is calculated based on the first average convection heat transfer coefficient and the second average convection heat transfer coefficient of the optical rod bundle assembly model under the preset physical condition; a second heat transfer correlation equation corresponding to the wire-wound fuel assembly model under the preset physical condition is calculated based on the correction factor and the first heat transfer correlation equation corresponding to the optical rod bundle assembly model under the preset physical condition. Thus, accurate analysis of the thermal-hydraulic characteristics of the wire-wound fuel assembly is achieved, and the heat transfer correlation equation corresponding to the wire-wound fuel assembly, i.e., the second heat transfer correlation equation, is determined.

[0016] An embodiment of the present invention provides a device for determining a heat transfer correlation equation of a wire-wound fuel assembly, the device comprising: a construction module, used to couple a wire-wound assembly model with a light-rod bundle assembly model to construct a wire-wound fuel assembly model; an acquisition module, used to acquire a first average convective heat transfer coefficient under a preset physical condition based on the wire-wound fuel assembly model; a first calculation module, used to calculate a correction factor based on the first average convective heat transfer coefficient and a second average convective heat transfer coefficient of the light-rod bundle assembly model under the preset physical condition; and a second calculation module, used to calculate a second heat transfer correlation equation corresponding to the wire-wound fuel assembly model under the preset physical condition based on the correction factor and the first heat transfer correlation equation corresponding to the light-rod bundle assembly model under the preset physical condition.

[0017] The device for determining the heat transfer correlation equation of a wire winding fuel assembly provided by the present invention has the beneficial effect of being able to achieve the same technical effect as the above-mentioned method for determining the heat transfer correlation equation of a wire winding fuel assembly. To avoid repetition, it will not be described here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0019] Figure 1 A schematic flow chart of a method for determining a heat transfer correlation equation for a wire-wound fuel assembly provided by an embodiment of the present invention; Figure 2 It is a schematic flow chart of a specific method for determining a heat transfer correlation equation of a wire-wound positioning fuel assembly in an embodiment of the present invention; Figure 3 It is a schematic structural diagram of a device for determining a heat transfer correlation equation of a wire winding positioning fuel assembly in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0021] The embodiment of the present invention provides a method for determining the heat transfer correlation of a wire-wound positioning fuel assembly, see Figure 1 A schematic flow chart of a method for determining a heat transfer correlation equation for a wire-wound fuel assembly is shown; the method comprises the following steps: S110, coupling the wire winding assembly model with the optical rod bundle assembly model to construct a wire winding positioning fuel assembly model.

[0022] S120, based on the above-mentioned wire winding positioning fuel assembly model, obtain a first average convection heat transfer coefficient under a preset physical condition.

[0023] Optionally, the above step S120 includes: based on the above preset physical conditions, setting the initial conditions and boundary conditions of the wire winding positioning fuel assembly model; wherein the initial conditions are the pressure field and temperature field of the fluid channel, the temperature field of the rod bundle and the temperature field of the wire winding, and the boundary conditions are the fluid inlet and outlet boundary positions, and the flow rate and temperature corresponding to the fluid inlet and outlet boundary positions; based on computational fluid dynamics (CFD), calculating the first physical parameters of the wire winding positioning fuel assembly model under the above preset physical conditions; and calculating the first average convection heat transfer coefficient according to the above first physical parameters and the first average convection heat transfer coefficient calculation formula.

[0024] Optionally, the first physical parameter includes a first heat flux density and a first temperature difference, wherein the first temperature difference is the temperature difference between the average temperature of the light rod surface and the wire winding surface and the mainstream temperature of the supercritical water.

[0025] The calculation formula of the first average convection heat transfer coefficient is as follows: , , in, For coordinates The corresponding first convection heat transfer coefficient is, For coordinates The corresponding first heat flux density is, For coordinates The corresponding first temperature difference is, is the first average convective heat transfer coefficient mentioned above, is the length of the light rod bundle.

[0026] It should be noted that the coordinates is the position coordinate along the axial direction of the light rod bundle.

[0027] S130, calculating a correction factor according to the first average convective heat transfer coefficient and the second average convective heat transfer coefficient of the optical rod cluster assembly model under the preset physical working condition.

[0028] Optionally, the step S130 includes: performing a ratio operation on the first average convective heat transfer coefficient and the second average convective heat transfer coefficient of the optical rod bundle assembly model to obtain a correction factor; The calculation formula corresponding to the above correction factor is as follows: , in, is the correction factor mentioned above, is the first average convective heat transfer coefficient mentioned above, is the second average convective heat transfer coefficient mentioned above.

[0029] S140, calculating a second heat transfer correlation equation corresponding to the wire winding positioning fuel assembly model under the preset physical working condition based on the correction factor and the first heat transfer correlation equation corresponding to the optical rod cluster assembly model under the preset physical working condition.

[0030] Optionally, the step S140 includes: performing a product operation on the correction factor and a first heat transfer correlation corresponding to the optical rod bundle assembly model to obtain a second heat transfer correlation; The second heat transfer correlation is as follows: , in, For coordinates The corresponding first Nusselt number is, For coordinates The corresponding second Nusselt number is, is the correction factor, For coordinates The corresponding Reynolds number is, is the Prandtl number, is the density of supercritical water in the mainstream area, represents the density of supercritical water near the wall, is the flow channel diameter.

[0031] Optionally, the method further includes: establishing an initial optical rod bundle assembly model according to the optical rod bundle structural parameters and material property parameters; calculating the third average convection heat transfer coefficient under the above-mentioned preset physical working condition according to the above-mentioned first heat transfer correlation equation and the standard average convection heat transfer coefficient calculation formula; wherein the third average convection heat transfer coefficient is the standard average convection heat transfer coefficient corresponding to the optical rod bundle assembly model; obtaining the fourth average convection heat transfer coefficient under the above-mentioned preset physical working condition based on the above-mentioned initial optical rod bundle assembly model; judging whether the relative error between the third average convection heat transfer coefficient and the fourth average convection heat transfer coefficient is less than a preset error; if not, adjusting the grid size and time step of the above-mentioned initial optical rod bundle assembly model until the preset error is met; if so, determining the fourth average convection heat transfer coefficient as the second average convection heat transfer coefficient; and constructing the above-mentioned optical rod bundle assembly model according to the finally determined grid size and time step.

[0032] Optionally, the fourth average convective heat transfer coefficient under the preset physical condition is obtained based on the initial optical rod bundle assembly model, including: setting the initial conditions and boundary conditions of the wire winding positioning fuel assembly model based on the preset physical condition; wherein the initial conditions are the pressure field and temperature field of the fluid channel and the temperature field of the rod bundle, and the boundary conditions are the fluid inlet and outlet boundary positions, and the flow rate and temperature corresponding to the fluid inlet and outlet boundary positions. Based on computational fluid dynamics, the second physical parameter of the wire winding positioning fuel assembly model under the preset physical condition is calculated. According to the second physical parameter and the second average convective heat transfer coefficient calculation formula, the fourth average convective heat transfer coefficient under the preset physical condition is calculated.

[0033] Optionally, the second physical parameter includes a second heat flux density and a second temperature difference. The second temperature difference is the temperature difference between the average temperature of the light rod surface and the mainstream temperature of the supercritical water; The second average convection heat transfer coefficient is calculated as follows: , , in, For coordinates The corresponding second convection heat transfer coefficient is, For coordinates The corresponding second heat flux density is, For coordinates The corresponding second temperature difference is, is the fourth average convective heat transfer coefficient mentioned above, is the length of the light rod bundle.

[0034] Optionally, the method further comprises: determining the correction factors and the second heat transfer correlation equation corresponding to the different preset physical working conditions according to the wire winding positioning fuel assembly model under different preset physical working conditions; preparing the correction factor table corresponding to the wire winding positioning fuel assembly according to the correction factors and the second heat transfer correlation equation corresponding to the different preset physical working conditions; The above-mentioned preset physical working conditions include preset temperature and preset pressure.

[0035] The present invention provides a method for determining a heat transfer correlation equation of a wire-wound fuel assembly. By coupling a wire-wound assembly model with a light-rod bundle assembly model, a wire-wound fuel assembly model is constructed to achieve accurate simulation of the wire-wound fuel assembly. Based on the above-mentioned wire-wound fuel assembly model, a first average convective heat transfer coefficient under a preset physical condition is obtained to achieve analysis of the thermal-hydraulic characteristics of the wire-wound fuel assembly. According to the above-mentioned first average convective heat transfer coefficient and the second average convective heat transfer coefficient of the above-mentioned light-rod bundle assembly model under the preset physical condition, a correction factor is calculated to quantify the difference in thermal-hydraulic characteristics between the wire-wound fuel assembly and the light-rod bundle assembly under the same physical condition. According to the above-mentioned correction factor and the first heat transfer correlation equation corresponding to the above-mentioned light-rod bundle assembly model under the above-mentioned preset physical condition, a second heat transfer correlation equation corresponding to the above-mentioned wire-wound fuel assembly model under the above-mentioned preset physical condition is calculated to determine the heat transfer correlation equation of the wire-wound fuel assembly.

[0036] The embodiment of the present invention also provides a specific method for determining the heat transfer correlation of the wire-wound positioning fuel assembly, see Figure 2 A schematic flow chart of a specific method for determining a heat transfer correlation equation for a wire-wound fuel assembly is shown, the method comprising the following steps: Step S202: Establish a high-precision water property library.

[0037] Exemplarily, a high-precision water property library is established based on a preset physical operating condition range; wherein the preset physical operating condition includes a preset pressure and a preset temperature. Specifically, if the preset temperature range is 300K-1000K, the preset pressure range is 19MPa-29MPa. A high-precision transcritical water property interface is set, and the physical properties of water are determined by looking up a user-defined file (UDF). The above user-defined files are divided into temperature and pressure to generate a high-precision water property library covering subcritical, quasi-critical and supercritical ranges; wherein the temperature is 300K-1000K, the temperature interval is 1K, the pressure is 19MPa-29MPa, and the pressure interval is 0.05MPa.

[0038] Step S204: constructing an initial optical rod bundle assembly model.

[0039] Exemplarily, a geometric model of the optical rod bundle assembly is constructed according to the structural parameters of the optical rods and the material property parameters, which is the above-mentioned initial optical rod bundle assembly model; wherein the structural parameters include the relative positions and sizes between the optical rods, and the material property parameters include the thermal conductivity of the bundle and the density, viscosity, specific heat capacity and thermal conductivity of supercritical water. Specifically, the geometric model of the optical rod bundle assembly includes a solid domain and a fluid domain, wherein the optical rod bundle is the solid domain, and water is the fluid domain. The working fluid in the solid domain is 316SS stainless steel, and the working fluid in the fluid domain is supercritical water. The material property library corresponding to the working fluid is called to set the material property parameters, and a fluid-solid coupling interface is set between the solid domain and the fluid domain. The solid domain is divided by a second-order hexahedral grid, and the fluid domain grid is divided by a tetrahedral grid, and the dimensionless wall distance at the wall grid is controlled ( ) is in the range of 30–300 to meet the requirements of the turbulence model SST k-omega.

[0040] Step S206: Based on the initial optical rod cluster assembly model, construct an optical rod cluster assembly model and determine a second average convection heat transfer coefficient.

[0041] Exemplarily, firstly, the high-precision water physical property library is called according to the preset physical working conditions, and the corresponding calculation conditions, monitoring parameters, iteration steps and convergence criteria are set. The calculation conditions include initial conditions and boundary conditions; the initial conditions are the pressure field and temperature field of the fluid channel and the temperature field of the rod bundle; the boundary conditions are the fluid inlet and outlet boundary positions, and the flow rate and temperature corresponding to the fluid inlet and outlet boundary positions. Then, by carrying out the CFD calculation corresponding to the optical rod bundle assembly, the heat flux density and temperature difference distribution at each position of the overall surface of the initial optical rod assembly model are obtained, that is, the second heat flux density and the second temperature difference, which is the temperature difference between the average temperature of the optical rod surface and the mainstream temperature of supercritical water. According to the second average convection heat transfer coefficient calculation formula, the average convection heat transfer coefficient is calculated, which is the fourth average convection heat transfer coefficient.

[0042] The above second average convection heat transfer coefficient is calculated as follows: , , in, For coordinates The corresponding second convection heat transfer coefficient is, For coordinates The corresponding second heat flux density is, For coordinates The corresponding second temperature difference is is the fourth average convective heat transfer coefficient, is the length of the light rod bundle.

[0043] By determining a commonly used empirical relationship applicable to the above-mentioned preset physical conditions, the standard average convective heat transfer coefficient is calculated, that is, the above-mentioned third average convective heat transfer coefficient. The embodiment of the present invention adopts the Bishop heat transfer correlation as the empirical relationship under the above-mentioned preset physical conditions. The above-mentioned Bishop heat transfer correlation is as follows: , in, For coordinates The corresponding first Nusselt number is, For coordinates The corresponding Reynolds number is, is the Prandtl number, is the density of supercritical water in the mainstream area, is the density of supercritical water near the wall, is the flow channel diameter.

[0044] The calculation formula corresponding to the above standard average heat transfer convection coefficient is as follows: , in, is the standard average convective heat transfer coefficient, For coordinates The corresponding first Nusselt number is, For coordinates The corresponding supercritical water thermal conductivity is, is the flow channel diameter, is the length of the light rod bundle.

[0045] Furthermore, by adjusting the grid size and time step, Relative to The relative error of is within the error range of the corresponding empirical relationship; based on the final adjusted grid size and time step, the optical rod bundle assembly model is constructed and the average convection heat transfer coefficient of the corresponding optical rod bundle assembly model is determined to be the above-mentioned second average convection heat transfer coefficient. Specifically, by setting the relative error threshold to 15%, Relative to The relative error of is within the above relative error threshold, thus achieving Relative to The relative error is within the error range of the corresponding empirical relationship.

[0046] Step S208: constructing a wire winding positioning fuel assembly model based on the optical rod bundle assembly model.

[0047] Exemplarily, the wire winding assembly model is coupled with the above-mentioned optical rod bundle assembly model to construct a wire winding positioning fuel assembly model. Specifically, the wire winding assembly model is constructed according to the wire winding structural parameters and material properties; wherein, the wire winding assembly belongs to the solid domain, and its working fluid is still 316SS stainless steel. Its wire winding assembly grid is divided by an unstructured grid, and the grid size is a grid size proportionally reduced by the diameter ratio of the wire and the optical rod as the initial value (for example: the original optical rod grid size is 1mm, the optical rod diameter is 10mm, and the wire diameter is 1mm, then the wire winding grid size is 0.1mm), so as to realize the construction of the wire winding assembly model. Following the optical rod bundle assembly model finally determined in step S206, the wire winding assembly grid is coupled with the optical rod bundle assembly grid using the merge common node method to control the dimensionless wall distance at the wall grid ( ) meets the requirements of the turbulence model SST-komega; the time step of the optical rod bundle assembly model is used as the initial time step of the model after grid coupling; and then a control group of different mesh sizes and step sizes of the wire-wound rod bundle assembly geometric model is set for sensitivity comparison (that is, after reducing the mesh size or time step, the average convective heat transfer coefficient changes very little, such as 1%), and the optimal mesh size and time step are selected to avoid the influence of the mesh size or time step on the average convective heat transfer coefficient, so as to ensure that the wire-wound positioning fuel assembly model can obtain an accurate average convective heat transfer coefficient and complete the construction of the wire-wound positioning fuel assembly model.

[0048] Step S210: Based on the wire winding positioning fuel assembly model and the high-precision water physical property library, a first average convective heat transfer coefficient is obtained.

[0049] Exemplarily, firstly, the high-precision water physical property library is called according to the preset physical working conditions, and the corresponding calculation conditions, monitoring parameters, iteration steps and convergence criteria are set. The calculation conditions include initial conditions and boundary conditions; the initial conditions are the pressure field and temperature field of the fluid channel, the temperature field of the rod bundle and the temperature field of the wire winding; the boundary conditions are the fluid inlet and outlet boundary positions, and the flow rate and temperature corresponding to the fluid inlet and outlet boundary positions. Then, by carrying out CFD calculations of the wire winding positioning fuel assembly, the heat flux density and temperature difference distribution on the surface of the light rod bundle and the wire winding surface are obtained, that is, the first heat flux density and the first temperature difference, which are the temperature difference between the average temperature of the light rod surface and the wire winding surface and the mainstream temperature of supercritical water. According to the first average convection heat transfer coefficient calculation formula, the average convection heat transfer coefficient is calculated, that is, the first average convection heat transfer coefficient. The calculation formula of the first average convection heat transfer coefficient is as follows: , , in, For coordinates The corresponding first convection heat transfer coefficient is, For coordinates The corresponding first heat flux density is, For coordinates The corresponding first temperature difference is, is the first average convective heat transfer coefficient mentioned above, is the length of the light rod bundle.

[0050] Step S212: Calculate a correction factor of the heat transfer correlation equation of the wire winding positioning rod bundle assembly based on the first average convection heat transfer coefficient and the second average convection heat transfer coefficient.

[0051] Exemplarily, according to the calculation formula corresponding to the correction factor, the correction factor considering the empirical relationship of the wire winding is calculated. The calculation formula corresponding to the above correction factor is as follows: , in, is the correction factor mentioned above, is the first average convective heat transfer coefficient mentioned above, is the second average convective heat transfer coefficient mentioned above.

[0052] Step S214: Calculate a corrected heat transfer correlation equation for the wire winding positioning rod cluster assembly based on the correction factor of the heat transfer correlation equation for the wire winding positioning rod cluster assembly.

[0053] Exemplarily, the modified Bishop heat transfer correlation formula, that is, the modified wire winding positioning rod bundle assembly heat transfer correlation formula is as follows: , in, For coordinates The corresponding first Nusselt number is, For coordinates The corresponding second Nusselt number is, is the correction factor, For coordinates The corresponding Reynolds number is, is the Prandtl number, is the density of supercritical water in the mainstream area, represents the density of supercritical water near the wall, is the flow channel diameter.

[0054] The determination principle of the above-mentioned modified heat transfer correlation equation of the wire winding positioning rod bundle assembly is: Correction Factor , which is equivalent to , thus we can get: , , in, That is the heat transfer correlation equation of the wire winding positioning rod bundle assembly, and the corrected heat transfer correlation equation is determined as: .

[0055] Step S216: Prepare a wire winding positioning fuel assembly correction factor table.

[0056] Exemplarily, the correction factors and corresponding heat transfer correlations under different physical conditions obtained through the above steps S202-S214 are tabulated according to temperature and pressure.

[0057] The purpose of the invention is to provide a method for correcting the heat transfer correlation of a supercritical water reactor fuel assembly taking into account the influence of wire winding. The method is based on the characteristics of wire winding positioning fuel rods in supercritical water reactors. By establishing a three-dimensional model of a wire winding positioning fuel assembly and a bare rod fuel assembly, setting the physical property interface and heat transfer correlation of transcritical water, and carrying out steady-state thermal hydraulic calculations, the flow field and temperature field of the fuel assembly are obtained, so as to analyze and determine the heat transfer correlation after considering wire winding.

[0058] The embodiment of the present invention provides a device for determining the heat transfer correlation of a wire-wound positioning fuel assembly, see Figure 3 A schematic diagram of a structure of a device for determining a heat transfer correlation equation of a wire-wound positioning fuel assembly is shown; the device comprises: The construction module 310 is used to couple the wire winding assembly model with the optical rod bundle assembly model to construct a wire winding positioning fuel assembly model.

[0059] The acquisition module 320 is used to acquire the first average convection heat transfer coefficient under the preset physical conditions based on the above-mentioned wire winding positioning fuel assembly model.

[0060] The first calculation module 330 is used to calculate the correction factor according to the first average convection heat transfer coefficient and the second average convection heat transfer coefficient of the optical rod cluster assembly model under the preset physical working condition.

[0061] The second calculation module 340 is used to calculate the second heat transfer correlation equation corresponding to the wire winding positioning fuel assembly model under the above-mentioned preset physical working conditions based on the above-mentioned correction factor and the first heat transfer correlation equation corresponding to the above-mentioned optical rod cluster assembly model under the above-mentioned preset physical working conditions.

[0062] The device for determining the heat transfer correlation equation of a wire winding fuel assembly provided by the present invention has the beneficial effect of being able to achieve the same technical effect as the above-mentioned method for determining the heat transfer correlation equation of a wire winding fuel assembly. To avoid repetition, it will not be described here.

[0063] Of course, those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the control device through a computer, and the program can be stored in a computer-readable storage medium. When the program is executed, it may include the processes of the above-mentioned method embodiments, wherein the storage medium may be a memory, a disk, an optical disk, etc.

[0064] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements. The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0065] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for determining a heat transfer correlation equation for a wire-wound fuel assembly, characterized in that: The method comprises the following steps: The wire winding assembly model is coupled with the optical rod bundle assembly model to construct a wire winding positioning fuel assembly model; Based on the wire winding positioning fuel assembly model, obtaining a first average convection heat transfer coefficient under a preset physical condition; Calculating a correction factor according to the first average convection heat transfer coefficient and a second average convection heat transfer coefficient of the optical rod cluster assembly model under the preset physical working condition; According to the correction factor and the first heat transfer correlation equation corresponding to the optical rod cluster assembly model under the preset physical working condition, a second heat transfer correlation equation corresponding to the wire winding positioning fuel assembly model under the preset physical working condition is calculated.

2. The method according to claim 1, characterized in that The step of obtaining a first average convection heat transfer coefficient under a preset physical condition based on the wire winding positioning fuel assembly model includes: Based on the preset physical working conditions, the initial conditions and boundary conditions of the wire-wound positioning fuel assembly model are set; wherein the initial conditions are the pressure field and temperature field of the fluid channel, the temperature field of the rod bundle, and the temperature field of the wire winding, and the boundary conditions are the fluid inlet and outlet boundary positions, and the flow rate and temperature corresponding to the fluid inlet and outlet boundary positions; Based on computational fluid dynamics, first physical parameters of the wire winding positioning fuel assembly model under the preset physical working condition are calculated; The first average convective heat transfer coefficient is calculated based on the first physical parameter and the first average convective heat transfer coefficient calculation formula.

3. The method according to claim 2, characterized in that The first physical parameter includes a first heat flux density and a first temperature difference, wherein the first temperature difference is the temperature difference between the average temperature of the light rod surface and the wire winding surface and the mainstream temperature of the supercritical water; The first average convective heat transfer coefficient is calculated as follows: ， ， in, For coordinates The corresponding first convection heat transfer coefficient is, For coordinates The corresponding first heat flux density is, For coordinates The corresponding first temperature difference is is the first average convective heat transfer coefficient, is the length of the light rod bundle.

4. The method according to claim 1, characterized in that: The correction factor is calculated based on the first average convection heat transfer coefficient and the second average convection heat transfer coefficient of the optical rod bundle assembly model under the preset physical working condition, including: Performing a ratio operation on the first average convective heat transfer coefficient and the second average convective heat transfer coefficient of the optical rod bundle assembly model to obtain a correction factor; The calculation formula corresponding to the correction factor is as follows: ， in, is the correction factor, is the first average convective heat transfer coefficient, is the second average convective heat transfer coefficient.

5. The method according to claim 1, characterized in that The second heat transfer correlation formula corresponding to the wire winding positioning fuel assembly model under the preset physical working condition is calculated based on the correction factor and the first heat transfer correlation formula corresponding to the optical rod cluster assembly model under the preset physical working condition, including: Performing a product operation on the correction factor and the first heat transfer correlation equation corresponding to the optical rod bundle assembly model to obtain the second heat transfer correlation equation; The second heat transfer correlation is as follows: ， in, For coordinates The corresponding first Nusselt number is, For coordinates The corresponding second Nusselt number is, is the correction factor, For coordinates The corresponding Reynolds number is, is the Prandtl number, is the density of supercritical water in the mainstream area, represents the density of supercritical water near the wall, is the flow channel diameter.

6. The method according to claim 1, characterized in that The method further comprises: According to the optical rod bundle structure parameters and material property parameters, an initial optical rod bundle component model is established; According to the first heat transfer correlation and the standard average convection heat transfer coefficient calculation formula, a third average convection heat transfer coefficient under the preset physical working condition is calculated; wherein the third average convection heat transfer coefficient is the standard average convection heat transfer coefficient corresponding to the optical rod bundle assembly model; Based on the initial optical rod bundle assembly model, obtaining a fourth average convection heat transfer coefficient under the preset physical working condition; Determine whether the relative error between the third average convective heat transfer coefficient and the fourth average convective heat transfer coefficient is less than a preset error; if not, adjust the grid size and time step of the initial optical rod bundle assembly model until the preset error is met; if so, determine the fourth average convective heat transfer coefficient as the second average convective heat transfer coefficient; The optical rod bundle assembly model is constructed according to the finally determined grid size and the time step.

7. The method according to claim 6, characterized in that The step of obtaining a fourth average convection heat transfer coefficient under the preset physical working condition based on the initial optical rod cluster assembly model includes: Based on the preset physical working conditions, the initial conditions and boundary conditions of the wire winding positioning fuel assembly model are set; wherein the initial conditions are the pressure field and temperature field of the fluid channel and the temperature field of the rod bundle, and the boundary conditions are the fluid inlet and outlet boundary positions and the flow rate and temperature corresponding to the fluid inlet and outlet boundary positions; Based on computational fluid dynamics, a second physical parameter of the wire winding positioning fuel assembly model under the preset physical working condition is calculated; The fourth average convective heat transfer coefficient is calculated based on the second physical parameter and the second average convective heat transfer coefficient calculation formula.

8. The method according to claim 7, characterized in that The second physical parameter includes a second heat flux density and a second temperature difference, wherein the second temperature difference is the temperature difference between the average temperature of the light rod surface and the mainstream temperature of the supercritical water; The second average convective heat transfer coefficient is calculated as follows: ， ， in, For coordinates The corresponding second convection heat transfer coefficient is, For coordinates The corresponding second heat flux density is, For coordinates The corresponding second temperature difference is, is the fourth average convective heat transfer coefficient, is the length of the light rod bundle.

9. The method according to claim 1, characterized in that: The method further comprises: According to the wire winding positioning fuel assembly model under different preset physical conditions, determining the correction factor and the second heat transfer correlation equation corresponding to different preset physical conditions; According to the correction factors corresponding to the different preset physical working conditions and the second heat transfer correlation equation, a correction factor table corresponding to the wire winding positioning fuel assembly is prepared; Wherein, the preset physical working conditions include preset temperature and preset pressure.

10. A device for determining heat transfer correlation of a wire-wound fuel assembly, characterized in that: The device includes: A construction module is used to couple the wire winding assembly model with the optical rod bundle assembly model to construct a wire winding positioning fuel assembly model; An acquisition module, used for acquiring a first average convection heat transfer coefficient under a preset physical condition based on the wire winding positioning fuel assembly model; A first calculation module, configured to calculate a correction factor according to the first average convection heat transfer coefficient and a second average convection heat transfer coefficient of the optical rod bundle assembly model under the preset physical working condition; The second calculation module is used to calculate the second heat transfer correlation equation corresponding to the wire winding positioning fuel assembly model under the preset physical working condition based on the correction factor and the first heat transfer correlation equation corresponding to the optical rod bundle assembly model under the preset physical working condition.

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