Flow distribution method and device of parallel multi-channel system and storage medium thereof

Abstract

The invention relates to the technical field of nuclear engineering, in particular to a flow distribution method and device for a parallel multi-channel system and a storage medium, and the distribution method comprises the following steps: constructing an initialization model, and initializing the inlet flow of each channel; calculating the total pressure drop delta pi of the inlet and outlet of each channel, vectorizing the flow distribution model to construct a vector function, and calculating a vector function value through the delta pi; judging whether the vector function absolute value is smaller than a specified error value; applying disturbance to the inlet flow of each channel, calculating the total pressure drop of the inlet and the outlet of each channel after disturbance, and obtaining and outputting the updated value of the inlet flow of each channel. The method solves the problems that an existing flow distribution model is low in efficiency and cannot ensure convergence of a trial and error process, and has the advantages of being high in operation speed, wide in application scene and high in robustness.

Description

Technical Field

[0001] The present invention relates to the field of nuclear engineering technology, and in particular to a flow distribution method, a device and a storage medium thereof for a parallel multi-channel system. Background Art

[0002] Parallel channels are widely used in nuclear engineering, electric power, petrochemical engineering and other engineering fields. In the field of nuclear engineering, some advanced reactors use closed fuel grids, and the coolant channels are only connected to the upper and lower chambers at the inlet and outlet. There is no flow mixing of the coolant in the channel, which can be regarded as a group of parallel channels. Therefore, when conducting full core thermal hydraulic analysis of such reactors, the parallel channel flow distribution problem must be solved first, because the coolant flow distribution characteristics are the basis of the fuel heat transfer process.

[0003] In flow distribution calculation, an isobaric surface is usually taken at the connection point of the upper and lower chambers of the channel inlet and outlet, and flow distribution is performed according to the law of equal pressure loss in parallel channels. Many researchers have established models based on this law and completed steady-state calculations of flow distribution. However, due to the technical secrets involved, existing studies have chosen to avoid the key technical issue of how to solve flow distribution.

[0004] At present, for the existing parallel multi-channel traffic allocation problem, the mathematical model describing its traffic allocation process, that is, the traditional traffic allocation model, is relatively unified and meets the following constraints:

[0005] (a) The mass of the fluid before and after the distribution at the inlet is conserved, that is:

[0006]

[0007] W t represents the total inlet flow, W i represents the inlet flow rate allocated to the i-th channel; N represents the total number of parallel channels, which represents the scale of the system, which can range from 2 to tens of thousands;

[0008] (b) The pressure drop between the inlet and outlet of each channel is approximately equal and can be written as:

[0009] Δp i =p i,in -p i,out =Δp ave (2)

[0010] Δp i is the pressure drop of channel i, and is the channel inlet pressure p i,in and the channel outlet pressure p i,out The difference between aveis the average pressure drop of all channels. If there are N channels, N-1 independent equations can be obtained through equation (8). Adding equation (2) will give N equations about the inlet flow rate. Since the number of equations is equal to the number of variables, the above equation system has a unique solution in theory.

[0011] In principle, we can continuously try and adjust the inlet flow rate W of each channel i , until the above equations are satisfied, then the solution is obtained by trial and error. However, since the pressure drop of the channel may be a non-monotonic function of the inlet flow rate, this is extremely inefficient and cannot guarantee the convergence of the trial and error process. Summary of the invention

[0012] The purpose of the present invention is to provide a flow distribution method, device and storage medium for a parallel multi-channel system, so as to solve the problem of efficient and stable numerical solution method for nonlinear, large-scale parallel multi-channel flow distribution theoretical model.

[0013] The embodiments of the present invention are implemented by the following technical solutions:

[0014] The present invention provides a flow distribution method for a parallel multi-channel system, which comprises:

[0015] S1, build an initialization model to initialize the inlet flow of each channel;

[0016] S2. Calculate the total pressure drop Δp of each channel inlet and outlet according to the initialized inlet flow value of each channel i , construct a vector function by vectorizing the traffic distribution model, and use Δp i Calculate the function value;

[0017] S3, determine whether the absolute value of the vector function is less than the specified error value, if it is satisfied, end the iteration and obtain the flow distribution result; otherwise, proceed to the next step;

[0018] S4. Apply disturbance ΔW to the inlet flow of each channel, and calculate the total pressure drop Δp of each channel after the disturbance i ';

[0019] S5. Calculate the Jacobian matrix according to the pressure drop before and after the disturbance, and calculate the updated value of the inlet flow of each channel.

[0020] Furthermore, the initialization model in step S1 is implemented using the following formula:

[0021]

[0022] Among them, W i represents the inlet flow allocated to the i-th channel; W t represents the total inlet flow; N represents the total number of parallel channels; kA represents the ratio of the cross-sectional area of ​​the i-th channel to the cross-sectional area of ​​the reference channel; k D It represents the ratio of the hydraulic diameter of the ith channel to the hydraulic diameter of the reference channel; the reference channel is preferably the first channel; n is a constant value, which can be taken as 0.25.

[0023] Furthermore, the method further comprises the following steps:

[0024] S6. Return to S2 and continue iterating until the absolute value of the vector function is less than the specified error value.

[0025] Furthermore, in step S2:

[0026] Δp i =p iin -p iout =Δp ave (2)

[0027] where Δp i is the pressure drop of channel i, that is, the channel inlet pressure p iin and the channel outlet pressure p iout The difference between ave is the average pressure drop of all channels;

[0028] The vector function for:

[0029]

[0030] Among them, c is an adjustment coefficient to ensure that the magnitude of the function values ​​of different components is close, defined as Δp ave / (W t / N).

[0031] Furthermore, in step S3, the Euler length of the multidimensional vector is used as a standard to judge the absolute value of the vector function and check whether the residual is less than the specified error limit ε:

[0032]

[0033] Among them, F i Represents a vector function The function value of the i-th component; the error limit ε is not greater than 0.001; for for

[0034] Furthermore, the value of the disturbance ΔW in step S4 does not exceed 5% of the arithmetic mean of the channel flow.

[0035] Furthermore, the step S5 further includes the following sub-steps:

[0036] S51, taking a difference in the pressure drop before and after the flow disturbance in each channel, and obtaining a Jacobian matrix;

[0037] S52, inverting the Jacobian matrix to obtain an inverse matrix of the Jacobian matrix;

[0038] S53, obtaining the updated value of the inlet flow of each channel.

[0039] Furthermore, in step S51, the following formula is used to differentiate the pressure drop before and after the flow disturbance in each channel:

[0040]

[0041] Among them, W i represents the inlet flow obtained by allocating the i-th channel; ΔW represents the flow disturbance value.

[0042] The Jacobian matrix is:

[0043]

[0044] Where, subscript i represents the i-th component of the vector; subscript j represents the j-th component of the vector;

[0045] The updated value of the inlet flow of each channel is obtained using the following formula:

[0046]

[0047] in, express The inverse matrix of , η represents the iterative relaxation factor; the superscript (k+1) represents the independent variable vector after the flow is updated; the superscript (k) represents the independent variable vector used in the previous step.

[0048] The present invention also provides an electronic device, comprising: a processor and a memory communicatively connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute the steps of the flow distribution method of the above-mentioned parallel multi-channel system.

[0049] Furthermore, the present invention also provides a computer-readable storage medium, on which is stored a program for implementing a flow distribution method for a parallel multi-channel system, and the program for implementing a flow distribution method for a parallel multi-channel system is executed by a processor to implement the steps of the above-mentioned flow distribution method for a parallel multi-channel system.

[0050] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0051] The present invention converts the parallel channel flow distribution mathematical model into a nonlinear vector equation root-finding problem, so as to realize a robust and rapid solution to the flow distribution problems of multiple channels, single-phase flow and two-phase flow; only the number of channels, geometric dimensions and inlet parameters need to be given, and the inlet flow of each channel can be accurately obtained by calculation; and the algorithm has strong robustness and high computational efficiency, and the numerical solution of the parallel channel flow distribution problem can be quickly determined by iteration; the present invention can be applied to single-phase, two-phase and mixed flows, that is, the situation where the pressure drop in the channel and the inlet flow are non-monotonic can also be solved; it is applicable to both steady-state calculations and transient calculations; the iterative solution method converges quickly, and when the number of channels increases, the effect of the present invention becomes more and more significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0053] Figure 1 A schematic diagram of a parallel channel flow distribution process provided by an embodiment of the present invention;

[0054] Figure 2 This is a flow chart of traffic allocation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0056] It should be understood that the "system", "device", "unit" and / or "module" used herein are a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

[0057] As shown in this specification and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0058] Flowcharts are used in this specification to illustrate the operations performed by the system according to the embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed precisely in order. Instead, the steps may be processed in reverse order or simultaneously. At the same time, other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0059] like Figure 1 As shown in the figure, for the existing parallel multi-channel traffic allocation problem, the traffic allocation model is relatively unified and meets the following constraints:

[0060] (a) The mass of the fluid before and after the distribution at the inlet is conserved, that is:

[0061]

[0062] W t represents the total inlet flow, W i represents the inlet flow rate allocated to the i-th channel; N represents the total number of parallel channels, which represents the scale of the system, which can range from 2 to tens of thousands;

[0063] (b) The pressure drop between the inlet and outlet of each channel is approximately equal and can be written as:

[0064] Δp i =o i,in -p i,out =Δp ave (2)

[0065] Δp i is the pressure drop of channel i, and is the channel inlet pressure p i,in and the channel outlet pressure p i,out The difference between ave is the average pressure drop of all channels. If there are N channels, equation (8) can be used to obtain N-1 independent equations. Adding equation (2) will give N equations about the inlet flow rate. Since the number of equations is equal to the number of variables, the above equations have a unique solution in theory.

[0066] In principle, we can continuously try and adjust the inlet flow rate W of each channel i , until the above equations are satisfied, then the solution is obtained by trial and error. However, since the pressure drop in the channel may be a non-monotonic function of the inlet flow rate, this is extremely inefficient and cannot guarantee the convergence of the trial and error process.

[0067] Therefore, an embodiment of the present application provides a flow distribution method for a parallel multi-channel system, including:

[0068] S1, build an initialization model to initialize the inlet flow of each channel;

[0069] S2. Calculate the total pressure drop Δp of each channel according to the inlet flow value of each channel i , constructing a vector function by vectorizing the traditional traffic distribution model, and using Δp i Calculate the function value;

[0070] S3, determine whether the absolute value of the vector function is less than the specified error value, if it is satisfied, end the iteration and obtain the flow distribution result; otherwise, proceed to the next step;

[0071] S4. Apply disturbance ΔW to the inlet flow of each channel, and calculate the total pressure drop Δp of each channel after the disturbance i ';

[0072] S5. Calculate the Jacobian matrix according to the pressure drop before and after the disturbance, and calculate the updated value of the inlet flow of each channel;

[0073] S6. Return to S2 and continue iterating until the absolute value of the vector function is less than the specified error value.

[0074] The implementation principle is to mathematically transform the model equations and propose a set of numerical solution formats, including the construction of iterative functions, initialization methods and iterative solution formats.

[0075] Specifically, a theoretical approximate solution is selected to initialize the iteration variable, and the initialization model in step S1 is implemented using the following formula:

[0076]

[0077] Among them, W i represents the inlet flow allocated to the i-th channel; W t represents the total inlet flow; N represents the total number of parallel channels; k A represents the ratio of the cross-sectional area of ​​the i-th channel to the area of ​​the reference channel; k D It represents the ratio of the hydraulic diameter of the ith channel to the hydraulic diameter of the reference channel; n is a constant value, which can be taken as 0.25.

[0078] Specifically, the reference channel is preferably the first channel.

[0079] Specifically, in step S2:

[0080] Δp i =p iin -p iout =Δp ave (2)

[0081] where Δp i is the pressure drop of channel i, that is, the channel inlet pressure p iin and the channel outlet pressure piout The difference between ave is the average pressure drop of all channels;

[0082] The equation group is converted into N equivalent equations, and an iterative format is constructed. The model proposed in the present invention is equivalent to a vector equation, and the vector function for:

[0083]

[0084] Among them, c is the adjustment coefficient given in advance, which makes the different function values ​​of the vector function close in magnitude. This value can be taken as Δp ave / (W t / N); F i (i=1.2...N) represents the components of the vector function.

[0085] Then the flow distribution model (8) and (2) can be transformed into the form of vector equation:

[0086]

[0087] in:

[0088]

[0089] The superscript T indicates transpose. and are all N-order vectors; thus, the iterative solution format can be constructed:

[0090]

[0091] In the above formula, the superscript k represents the number of iterative calculations; the superscript -1 represents matrix inversion; J represents the Jacobian matrix. Since the parallel channels are separated from each other, the pressure drop of any channel is approximately only a function of the inlet flow rate of the channel and has nothing to do with the other channels. Therefore, the corresponding Jacobian matrix It can be approximately simplified to a sparse matrix:

[0092]

[0093] This is a full-rank N-order equation system, so it can be inverted and then iterated based on equation (7).

[0094] Specifically, in step S51, the following formula is used to calculate the flow rate of each channel before and after the disturbance:

[0095] The voltage drop is differentiated as follows:

[0096]

[0097] Among them, W irepresents the inlet flow allocated to the i-th channel;

[0098] For a parallel system consisting of N channels, (5) is calculated N times to obtain N differential values; then the Jacobian matrix can be determined by substituting them into (6).

[0099] Specifically, the updated value of the inlet flow of each channel is obtained using the following formula:

[0100]

[0101] in, express The inverse matrix of , η represents the iterative relaxation factor, the superscript (k+1) represents the independent variable vector after the flow is updated; the superscript (k) represents the independent variable vector used in the previous step.

[0102] Test calculations show that for the iterative format proposed in the present invention, the mass conservation equation is always automatically satisfied. Therefore, it is only necessary to appropriately set the error limit by adjusting the coefficient c according to the actual calculation accuracy requirements; for single-phase flow, the error limit should be smaller; for two-phase flow, the error limit can be larger; but in general, the error limit should not be greater than one thousandth of the average pressure drop in the channel.

[0103] Specifically, in this embodiment, one iteration needs to calculate the pressure drop twice. One is to determine whether the convergence standard is met after the pressure drop is obtained, and the other is to apply a small disturbance to the independent variable and then calculate the pressure drop. The purpose of doing this is to calculate the partial derivatives, thereby calculating the Jacobian matrix, which is used to obtain the flow update value, that is, the independent variable value for the next iterative calculation.

[0104] The present invention also provides an electronic device, comprising: a processor and a memory communicatively connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute the steps of the flow distribution method of the above-mentioned parallel multi-channel system.

[0105] Specifically, the present invention also provides a computer-readable storage medium, on which is stored a program for implementing a flow distribution method for a parallel multi-channel system, and the program for implementing a flow distribution method for a parallel multi-channel system is executed by a processor to implement the steps of the above-mentioned flow distribution method for a parallel multi-channel system.

[0106] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of this specification. Although not explicitly stated here, those skilled in the art may make various modifications, improvements and corrections to this specification. Such modifications, improvements and corrections are suggested in this specification, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of this specification.

[0107] At the same time, this specification uses specific words to describe the embodiments of this specification. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of this specification. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of this specification can be appropriately combined.

[0108] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences described in this specification, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some invention embodiments that are currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the attached claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the essence and scope of the embodiments of this specification. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing server or mobile device.

[0109] Similarly, it should be noted that in order to simplify the description disclosed in this specification and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this specification, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the subject matter of this specification are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0110] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, as an example and not a limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly introduced and described in this specification.

Claims

1. A flow distribution method for a parallel multi-channel system, characterized in that: include: S1, build an initialization model to initialize the inlet flow of each channel; S2. Calculate the total pressure drop Δp of each channel inlet and outlet according to the initialized inlet flow value of each channel i , construct a vector function by vectorizing the traffic distribution model, and use Δp i Calculate the function value; S3, determine whether the absolute value of the vector function is less than the specified error value, if it is satisfied, end the iteration and obtain the flow distribution result; otherwise, proceed to the next step; S4. Apply disturbance ΔW to the inlet flow of each channel, and calculate the total pressure drop Δp of each channel after the disturbance i '; S5. Calculate the Jacobian matrix according to the pressure drop before and after the disturbance, and calculate the updated value of the inlet flow of each channel.

2. The flow distribution method of the parallel multi-channel system according to claim 1, characterized in that: The initialization model in step S1 is implemented by the following formula: Among them, W i represents the inlet flow allocated to the i-th channel; W t represents the total inlet flow; N represents the total number of parallel channels; k A represents the ratio of the cross-sectional area of ​​the i-th channel to the cross-sectional area of ​​the reference channel; k D It represents the ratio of the hydraulic diameter of the ith channel to the hydraulic diameter of the reference channel; the reference channel is preferably the first channel; n is a constant value, which can be taken as 0.

25.

3. The flow distribution method of the parallel multi-channel system according to claim 1, characterized in that: The following steps are also included: S6. Return to S2 and continue iterating until the absolute value of the vector function is less than the specified error value.

4. The flow distribution method of the parallel multi-channel system according to claim 1, characterized in that: In step S2: Δp i =p iin -p iout =Δp ave (2) Where Δp i is the pressure drop of channel i, that is, the channel inlet pressure p iin and the channel outlet pressure p iout The difference between ave is the average pressure drop of all channels; The vector function for: Among them, c is an adjustment coefficient to ensure that the magnitude of the function values ​​of different components is close, defined as Δp ave / (W t / N).

5. The flow distribution method of the parallel multi-channel system according to claim 1, characterized in that: In step S3, the Euler length of the multidimensional vector is used as a standard to judge the absolute value of the vector function and check whether the residual is less than the specified error limit ε: Among them, F i Represents a vector function The function value of the i-th component; the error limit ε is not greater than 0.001; for 6. The flow distribution method of a parallel multi-channel system according to claim 1, characterized in that: The value of the disturbance ΔW in step S4 does not exceed 5% of the arithmetic mean value of the channel flow.

7. The flow distribution method of a parallel multi-channel system according to claim 1, characterized in that: The step S5 further comprises the following sub-steps: S51, taking a difference in the pressure drop before and after the flow disturbance in each channel, and obtaining a Jacobian matrix; S52, inverting the Jacobian matrix to obtain an inverse matrix of the Jacobian matrix; S53, obtaining the updated value of the inlet flow of each channel.

8. The flow distribution method of the parallel multi-channel system according to claim 7, characterized in that: In step S51, the following formula is used to differentiate the pressure drop before and after the flow disturbance in each channel: Among them, W i represents the inlet flow obtained by allocating the i-th channel; ΔW represents the flow disturbance value. The Jacobian matrix is: Where, subscript i represents the i-th component of the vector; subscript j represents the j-th component of the vector; The updated value of the inlet flow of each channel is obtained using the following formula: in, express The inverse matrix of , η represents the iterative relaxation factor; the superscript (k+1) represents the independent variable vector after the flow is updated; the superscript (k) represents the independent variable vector used in the previous step.

9. An electronic device, characterized in that: The electronic device includes: a processor and a memory communicatively connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor can execute the steps of the flow distribution method for a parallel multi-channel system as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program for implementing a flow distribution method for a parallel multi-channel system, and the program for implementing a flow distribution method for a parallel multi-channel system is executed by a processor to implement the steps of the flow distribution method for a parallel multi-channel system described in any one of claims 1 to 8.

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