A simulation method for fluid distribution in hydrogen fuel cell stacks with simplified calculation difficulty

Abstract

The present invention relates to a simulation method for fluid distribution of a hydrogen fuel cell stack that simplifies the difficulty of calculation, including: obtaining the dimensions of a common manifold and a fuel cell flow channel, creating a three-dimensional or two-dimensional geometric model of a hydrogen fuel cell stack; determining the inlet and outlet boundary conditions of the stack; creating a geometric model of stack fluid distribution, using the viscous force term in the Brinkman equation based on porous media to simulate the local resistance loss caused by the geometric structure of the common manifold distribution fluid of the fuel cell stack, and determining the local resistance loss coefficient through simulation; considering the roughness of the surface of the common manifold flow channel; calibrating the resistance loss coefficient through the inlet and outlet boundary conditions of the stack, adjusting the resistance coefficient of the battery flow channel to meet the requirements, and determining the resistance coefficient of the battery flow channel; after the model is built, calculating the stack fluid distribution result through simulation. Compared with the prior art, the present invention has the advantages of reducing the deviation of simulation results, ensuring the effectiveness of calculation, and improving the calculation precision and accuracy of the model.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a hydrogen fuel cell stack fluid distribution simulation method which simplifies the calculation difficulty. Background Art

[0002] As a new energy source, hydrogen fuel cells have the advantages of high energy efficiency, no pollution, fast start-up speed and low operating temperature. They are widely used in the automotive field, fixed and portable power generation and other fields. The voltage that a single hydrogen fuel cell can generate is limited. For example, the proton exchange membrane fuel cell in a hydrogen fuel cell can usually only generate a voltage of less than 1V due to various losses. Therefore, in order to effectively meet the voltage and power requirements in actual vehicle applications, multiple battery units can be connected in series to assemble a hydrogen fuel cell stack.

[0003] The low reliability, poor durability and high cost of hydrogen fuel cells seriously affect the widespread commercial application of fuel cell vehicles. When hydrogen fuel cells are connected in series to form a hydrogen fuel cell stack, the distribution of fluids such as hydrogen, air, and cooling water in the fuel cell stack becomes crucial. The attenuation of single cell performance will lead to a decrease in the performance of the entire stack, which is the famous short board effect. The more cells in a hydrogen fuel cell stack, the greater the power that can be generated, but the number of cells in a hydrogen fuel cell stack cannot be increased indefinitely. One of the reasons is that the consistency of fluid distribution in the stack (hydrogen fuel cell stack) will deteriorate as the number of cells in the stack increases. From the perspective of electrode kinetics and thermodynamics, when the consistency of fluid distribution deteriorates, the deviation of battery performance in the stack will also increase, thereby reducing the output of the overall stack performance.

[0004] The flow channel of a single cell (hydrogen fuel cell) is very fine, usually at the millimeter level, or even less than one millimeter, and a high-power battery stack requires hundreds of batteries to be connected in series, which results in the complexity of the battery stack geometry. In order to measure the consistency of the fluid distribution of the battery stack and its impact on performance through experimental methods, it is necessary to arrange micro sensors inside the flow channel to monitor the fluid distribution of each battery while ensuring that it does not affect the normal operation of the battery stack, which requires huge experimental costs. Similarly, due to the complexity of the battery stack geometry, if you want to simulate the fluid distribution of the complete battery stack geometry through simulation methods, the number of grids required to be divided is huge, and from the perspective of computing resources and computing costs, the difficulty is also great.

[0005] The existing simulation method for simplifying the fluid distribution of the battery stack usually simplifies the flow channel of the single cell of the battery stack into a straight flow channel, and then simplifies the distribution flow channel of the common manifold of the battery stack from the perspective of the entire three-dimensional structure to form a simplified three-dimensional geometric model (such as Figure 1 ), or directly simplify the battery stack geometry model into a two-dimensional model (as shown in Figure 2As shown). The simplified battery flow channel is replaced by a porous medium. Through the setting and fitting of the resistance coefficient, although the geometric model has been simplified, the calculated pressure drop at the inlet and outlet of the battery stack fluid can still be consistent with the actual situation, thereby simulating the consistency of the battery stack fluid distribution. In addition, the existing simulation method of battery stack fluid distribution usually adds a resistance coefficient to the battery flow channel, but does not pay too much attention to the setting of other parameters. Such as the size of the battery flow channel and the common manifold of the battery stack, the local resistance loss, the roughness of the wall of the common manifold of the battery stack, etc. After simplification, the flow channel of the battery itself does not need to be consistent with the actual structure and size, but if the cross-sectional area of ​​the flow channel is too small, it will increase the turbulence effect at the junction of the common manifold of the battery stack and the battery flow channel, and it is easy to cause the calculation to not converge. In the three-dimensional simplified model, the size of the common manifold needs to be consistent with the actual situation; in the two-dimensional simplified model, the size of the common manifold of the battery stack also needs to be consistent with the cross-section of the actual common manifold, because this ensures the consistency of the speed, which is a very important parameter in the common manifold. The pressure loss caused by the geometric structure of the stack includes not only the resistance loss along the way, but also the local resistance loss caused by the change of the geometric structure. Therefore, if the roughness of the common manifold of the stack and the local pressure loss are not considered, the calculated pressure drop of the inlet and outlet of the stack will be in compliance, but in fact the pressure of the battery flow channel will be calculated too high, and the pressure loss of the common manifold of the stack will be calculated too low, which will cause the calculation result of the consistency of the fluid distribution of the stack to be too ideal. Therefore, how to provide a hydrogen fuel cell stack fluid distribution simulation method that can simplify the calculation difficulty, take into account various pressure losses, and ensure the effectiveness of the simulation method has become a problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty, the method comprising:

[0009] Based on the actual hydrogen fuel cell stack situation, the size of the common manifold is obtained, and based on the size of the common manifold, the appropriate flow channel size of the fuel cell is obtained, and then a three-dimensional geometric model or a two-dimensional geometric model of the hydrogen fuel cell stack is created as a simplified model;

[0010] Based on the experimental data, determine the inlet boundary conditions and outlet boundary conditions of the fuel cell stack;

[0011] Based on the 3D geometric model of the hydrogen fuel cell stack, create a geometric model of the stack fluid distribution;

[0012] The viscous force term in the Brinkman equation based on porous media is used to simulate the local resistance loss caused by the geometric structure of the common manifold of the fuel cell stack to distribute the fluid. Through simulation, the local resistance loss coefficient is continuously adjusted to meet the requirements, and the local resistance loss coefficient of the common manifold of the fuel cell stack to distribute the fluid is determined;

[0013] The roughness of the common manifold flow channel surface is obtained through actual measurement;

[0014] The resistance coefficient of the battery flow channel is determined by adjusting the inlet boundary conditions and outlet boundary conditions that are consistent with the actual conditions through experiments, and then the resistance coefficient of the battery flow channel is determined after the resistance coefficient of the battery flow channel is continuously adjusted to meet the requirements;

[0015] The model is built and the stack fluid distribution results are calculated through simulation.

[0016] Furthermore, in the three-dimensional geometric model or the two-dimensional geometric model of the hydrogen fuel cell stack, the cross-sectional size of the flow channel of the fuel cell is not less than 1 / A of the size of the common manifold, and the value of A is determined based on the convergence of the calculation and the calculation time.

[0017] Furthermore, based on the experimental data, the specific contents of the inlet boundary conditions and outlet boundary conditions of the fuel cell stack are determined as follows:

[0018] The inlet volume flow rate and outlet volume flow rate of the fuel cell stack are obtained through experiments, and the volume flow rate conditions of the inlet manifold of the fuel cell stack are determined; the inlet and outlet pressures of the fuel cell stack are obtained through experiments, and the pressure boundary conditions of the outlet manifold of the fuel cell stack are determined.

[0019] Furthermore, in the present invention, before determining the local resistance loss coefficient at the common manifold of the stack where the fluid is distributed, the pressure loss at the common manifold of the stack can be known according to the incompressible flow equation of the pipeline:

[0020]

[0021] Where ΔP is the pressure drop between the common manifolds of the stack, f is the friction coefficient, L is the flow path length, and D h is the hydraulic diameter, ρ is the fluid density, is the average velocity of the fluid, K L is the local drag coefficient. It is determined that the local drag loss term is proportional to the square of the speed, which provides a direction for the equivalent simplified simulation method of local drag loss.

[0022] Furthermore, the method of the present invention uses a porous medium region to simulate the actual pressure drop of the fuel cell flow channel, and simulates the specific contents of the local resistance loss that affects the pressure drop between the common manifolds of the fuel cell stack:

[0023] Based on the geometric model of fluid distribution in the battery stack, the geometric area where the fuel cell flow channel and the common manifold distribute fluid to the fuel cell flow channel is set as a porous medium area. The set porous medium area includes a first area representing the fuel cell flow channel and two second areas arranged on both sides of the first area and intersecting with the fuel cell flow channel and the common manifold flow channel. The porous medium setting area of ​​the first area is used to simulate a realistic pressure drop in the simplified battery flow channel model, and the porous medium setting areas of the two second areas are used to simulate the local resistance loss at the common manifold.

[0024] The resistance coefficient of the first region is achieved by setting the permeability and porosity, and the local resistance loss of the second region, which is proportional to the square of the velocity of the fluid, is simulated and determined by setting the porosity and the viscosity coefficient.

[0025] The permeability and porosity of the first region are set based on the Brinkman equation, and its differential form is as follows:

[0026]

[0027]

[0028]

[0029] Where μ is the dynamic viscosity, k is the permeability of the porous medium, β is the viscosity coefficient of non-Darcy flow, u is the fluid velocity, F is the external force, P is the pressure, and Q is m is the mass source term, ε p is the porosity of the porous medium, I is the unit matrix;

[0030] The first region simulates pressure losses without considering the viscous force option for non-Darcy flow.

[0031] The local resistance loss in the second area is set by setting the porosity of the Brinkman equation to 1, when the permeability option does not exist, and adding the viscous force term of the non-Darcy flow to simulate the local resistance loss; the local resistance loss coefficient is determined by comparing and fitting the simulation calculations of two models with a common manifold to distribute the fluid and a simplified geometric structure.

[0032] Furthermore, the determination of the local resistance loss coefficient is realized by the simulation comparison fitting method in the following specific contents:

[0033] Create a simplified model corresponding to the real distribution manifold and a simplified model corresponding to the simplified distribution manifold. Given the same inlet boundary conditions and outlet boundary conditions for the two geometric models, adjust the model to the case where the flow rate allocated to each battery flow channel in the two models is the same. Then set the local resistance coefficient in the simplified model corresponding to the simplified distribution manifold, and continuously fit it with the flow calculation results of the real distribution manifold until the deviation between the common manifold pressure distribution of the simplified case and the real case is less than 5% under different inlet boundary conditions, and then determine the local resistance loss coefficient at this time.

[0034] Furthermore, the specific content of determining the resistance coefficient of the battery flow channel is:

[0035] In the simplified model, the previously determined local resistance loss coefficient is set, and the same inlet flow and outlet pressure boundary conditions are given to the simplified model and the experiment, and the resistance coefficient of the battery flow channel is continuously adjusted. If, under different inlet flow boundary conditions, the deviation between the simulated inlet and outlet pressure difference of the common manifold of the battery stack and the actual inlet and outlet pressure difference is less than 5%, it is determined that the resistance coefficient of the battery flow channel at this time has been adjusted, and then the resistance coefficient of the battery flow channel at this time is determined.

[0036] The hydrogen fuel cell stack fluid distribution simulation method provided by the present invention with simplified calculation difficulty has at least the following beneficial effects compared with the prior art:

[0037] 1) The present invention proposes a simulation method that simplifies the difficulty of calculation and can effectively simulate the fluid distribution of the battery stack, thereby solving the problem that it is difficult to know the consistency of the battery stack distribution; the deviation of the simulation result can be reduced by specifying and selecting the geometric dimensions of the model in detail; the pressure loss caused by the flow of the fluid is related to the speed, and the common manifold size set by the present invention ensures that the fluid cross-section of the common steam pipe is consistent with the actual one, avoiding the speed calculation deviation and model calculation error caused by the change of size; at the same time, the present invention reasonably simplifies the battery flow channel geometric model, which can ensure the effectiveness of the calculation.

[0038] 2) The solution of the present invention takes into account the pressure loss of the common manifold caused by roughness and local resistance coefficient, and successfully builds a bridge between theory and model implementation, greatly improving the calculation precision and accuracy of the model. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A simplified three-dimensional geometric model schematic diagram of a hydrogen fuel cell stack in the prior art;

[0040] Figure 2 A simplified two-dimensional geometric model schematic diagram of a hydrogen fuel cell stack in the prior art;

[0041] Figure 3 A fluid distribution network diagram of a battery stack using a U-shaped structure flow field of the battery stack as an example in the embodiment;

[0042] Figure 4 An example diagram of a current common manifold fluid distribution geometric model in an embodiment;

[0043] Figure 5 A schematic diagram of porous medium region settings proposed in the hydrogen fuel cell stack fluid distribution simulation method of the present invention that simplifies the computational difficulty in the embodiment;

[0044] Figure 6 : is a geometric model of fluid distribution of a stack with the same inlet and outlet conditions in the embodiment, wherein sub-figure (a) is a simplified model schematic diagram corresponding to a real distribution manifold, and sub-figure (b) is a simplified model schematic diagram corresponding to a simplified distribution manifold;

[0045] Figure 7 It is a schematic flow chart of a hydrogen fuel cell stack fluid distribution simulation method that simplifies the calculation difficulty in the embodiment of the present invention. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should belong to the scope of protection of the present invention.

[0047] Example

[0048] The present invention relates to a hydrogen fuel cell stack fluid distribution simulation method that simplifies the computational difficulty. The method can not only simplify the computational difficulty in the distribution simulation process, but also take into account various pressure losses, thereby ensuring the effectiveness of the simulation method. This embodiment will comprehensively explain and specify the simulation scheme, and explain the selection of the geometric dimensions of the simplified model.

[0049] This embodiment takes the U-shaped structure flow field of the battery stack as an example, and the battery stack fluid distribution network diagram is as follows Figure 3 As shown, the fluid first enters from the inlet of the common manifold of the battery stack, and then is distributed in the common manifold. After being distributed to the battery flow channel, the fluid is merged and then flows out from the outlet between the common manifolds of the battery stack. in and P out are the inlet and outlet pressures of the common manifold of the stack, respectively; ΔP in (i) and ΔP out (i) is the inlet pressure loss and outlet pressure loss between the common manifolds of the stack; P(i) is the pressure loss between the battery flow channels; Q in (i) and Q out(i) are the flow rates between the common manifolds of the fuel cell stack.

[0050] Existing simulation methods usually ignore the influence of local resistance loss and the roughness of the common manifold. Although the simulated inlet pressure and outlet pressure are consistent with the actual ones, the ΔP calculated in the simulation model is in and ΔP out It will be too small, and the calculated result of the pressure drop of the flow channel will be too large, that is, the setting value of the resistance coefficient will be too large. The following formula will explain in detail.

[0051] Inlet pressure P in and outlet pressure P out The difference should be equal to the pressure drop of the Nth battery flow channel plus the pressure drop between the common manifolds:

[0052] P in -P out =p(N)+ΔP in (N)+ΔP out (N)

[0053] Under the premise that the inlet pressure and outlet pressure are determined, only the pressure drop between the manifolds and the pressure drop in the battery flow channel affect the distribution of the fluid. In the flow direction of the inlet and outlet common manifolds, the pressure gradually decreases, but it should be noted that the flow direction of the common manifold and the outlet common manifold is opposite in the U-shaped flow field structure. The relationship between the pressure between the inlet and outlet common manifolds and the pressure between the battery flow channels is as follows:

[0054] P in (i-1) = P in (i)-ΔP in (i-1)

[0055] P out (i) = P out (i-1)-ΔP out (i-1)

[0056] P(i)=P in (i)-P out (i)

[0057] The pressure relationship between the i-1th battery and the i-th battery is:

[0058] P(i-1)=(P in (i)-ΔP in (i-1))-(Po ut (i)+ΔP out (i-1))

[0059] P(i-1)=P(i)-(ΔP in (i-1)+ΔP out(i-1))

[0060] Therefore, we can know that ΔP in and ΔP out The calculated result will lead to a relatively small pressure drop deviation between different battery flow channels. At the same time, the increase in the resistance coefficient will make the calculated pressure drop of the battery flow channel itself larger, and the pressure drop value of the common manifold will be smaller than the pressure drop value of the battery flow channel. Pressure controls the flow of fluid. Under the combined effect of these two factors, the pressure deviation between different batteries will become smaller, so the calculated fluid distribution consistency result will be too ideal.

[0061] The method of the present invention provides a quantitative method for determining whether the model debugging is completed. Simulation is only a simulation method and can never be completely consistent with the actual situation. Therefore, as long as the pressure deviations of the inlet and outlet are less than 5% under different inlet conditions, the model can be used.

[0062] Combination Figure 7 As shown, in the method of the present invention, the size of the geometric model needs to be determined first.

[0063] 1. Determination of geometric model size:

[0064] The size and shape of the common manifold in the three-dimensional model should be consistent with the actual one, and the size and shape of the common manifold in the two-dimensional model should be consistent with the cross section of the actual manifold. The design of the flow channel cross-sectional dimensions (including width and length) of the fuel cell should not be less than 1 / A of the common manifold cross-sectional dimensions. The selection of the A value is related to the size of the common manifold. The selection of the flow channel dimension should not be too small. Through the trial calculation of the model, the appropriate A value is finally determined based on the convergence of the calculation and the calculation time. Generally, the specific selection of the A value cannot be too small, and the A value should be greater than 1. The length of the flow channel can be appropriately selected, and generally the length of the actual battery flow channel can be taken.

[0065] 2. Determination of import and export conditions:

[0066] Stack inlet volume flow rate Q in (N) and outlet volume flow rate Q out (N) is given by experimental data. It is known that in the simulation model, the stack inlet manifold is given a volume flow rate condition (or boundary condition types that can be converted to each other, such as velocity and mass flow rate). The stack outlet pressure P out (N) is given by experimental data. It is known that in the simulation model, the stack outlet manifold is given a pressure boundary condition.

[0067] 3. Determination of local resistance loss coefficient:

[0068] An example of a geometric model for fluid distribution in a common manifold of a fuel cell stack is shown below: Figure 4As shown, according to the incompressible flow equation of the pipeline, the pressure drop ΔP between the common manifolds of the stack is obtained:

[0069]

[0070] Where f is the friction coefficient, L is the flow path length, and D h is the hydraulic diameter, ρ is the fluid density, is the average velocity of the fluid, K L is the local drag coefficient.

[0071] The pressure drop (pressure loss) between manifolds includes not only the loss along the way including the friction coefficient, but also the local resistance loss caused by the change of the cross section due to the change of the geometric structure. The present invention takes both losses into consideration, especially the local resistance loss. The local resistance loss is proportional to the square of the velocity, so the viscosity term of the non-Darcy flow in the Brinkman equation of the porous area can be used to simulate the local resistance loss, which can simplify the calculation difficulty caused by the complex geometric structure.

[0072] like Figure 5 As shown, the present invention sets the geometric area where the fuel cell flow channel and the common manifold distribute fluid to the fuel cell flow channel as a porous medium area, and the porous area includes area 2 representing the fuel cell flow channel, and areas 1 and 3 where the fuel cell flow channel and the common manifold flow channel intersect. The present invention not only sets area 2 as a porous medium, but also sets porous media in areas 1 and 3. The porous medium setting of area 2 is to be able to simulate the actual pressure drop in the simplified battery flow channel model; the porous medium setting area of ​​areas 1 and 3 is mainly to be able to simulate local resistance loss.

[0073] Taking the application of the Brinkman equation as an example, the Brinkman equation combines the NS equation and Darcy's law and expands them. For incompressible flow with neglected inertia terms, the Brinkman differential equation is expressed as follows:

[0074]

[0075]

[0076]

[0077] Where μ is the dynamic viscosity, k is the permeability of the porous medium, β is the viscous force coefficient of non-Darcy flow, u is the fluid velocity, F is the external force, P is the pressure, and Q is m is the mass source term, ε p is the porosity of the porous medium, I is the unit matrix, is the gradient operator, Is the divergence operator.

[0078] The resistance coefficient of region 2 can be achieved by setting the permeability and porosity, and canceling the viscous force option of non-Darcy flow; in regions 1 and 3, the present invention is mainly to simulate the local resistance loss proportional to the square of the velocity, so the viscosity option of non-Darcy flow can be added and the porosity can be set to 1. In this way, the local resistance loss can be simulated by setting the viscous force coefficient, and the loss along the NS equation is also included.

[0079] The local resistance loss coefficient can be determined by simulation comparison and fitting. The local resistance loss coefficient only needs to help us determine the pressure loss in the common manifold, so the battery flow channel model can be simplified. Figure 6 As shown, given the same inlet and outlet conditions for two geometric models, the model is adjusted to make the flow allocated to each battery in the two models equal, and then the local resistance coefficient in the simplified distribution manifold model is set and continuously fitted with the flow calculation results of the real distribution manifold until the deviation between the common manifold pressure distribution of the simplified case and the real case under different inlet conditions is less than 5%. At this time, the local resistance loss coefficient can be determined.

[0080] 4. Determination of the roughness of the manifold flow channel surface:

[0081] The roughness ζ can be measured experimentally. After the roughness is measured, the wall roughness of the common manifold is set.

[0082] 5. Determination of resistance coefficient of battery flow channel:

[0083] By giving inlet and outlet boundary conditions that are consistent with the actual ones, the resistance coefficient of the battery flow channel is continuously adjusted. If, under different inlet flow boundary conditions, the deviation between the simulated inlet and outlet pressure difference of the common manifold of the battery stack and the actual one is less than 5%, it is considered that the resistance coefficient has been adjusted at this time.

[0084] 6. Calculation completed:

[0085] At this point, the resistance coefficients are all adjusted, the model is built, and calculations can be made. The stack fluid distribution results can be studied through simulation.

[0086] The scheme of the present invention proposes a simulation method that simplifies the difficulty of calculation and can effectively simulate the fluid distribution of the battery stack, solving the problem that it is difficult to know the consistency of the battery stack distribution. The present invention specifies and explains the geometric dimensions of the model in detail. Inappropriate selection of geometric dimensions will lead to deviations in simulation results. The pressure loss caused by the flow of fluid is related to the speed. The common manifold size specified in the present invention ensures that the fluid cross-section of the common manifold is consistent with the actual one, avoiding speed calculation deviations and model calculation errors caused by size changes. At the same time, the present invention reasonably simplifies the geometric model of the battery flow channel, and on the premise of ensuring the effectiveness of the calculation, an explanation is given to the establishment of the geometric dimensions of the flow channel. The scheme of the present invention takes into account the pressure loss of the common manifold caused by roughness and local resistance coefficient, and successfully builds a bridge between the theory and the realization of the model, greatly improving the calculation precision and accuracy of the model.

[0087] The solution of the present invention provides a quantitative method for determining whether the model debugging is completed. Simulation is only a simulation method and can never be completely consistent with the actual situation. Therefore, as long as the pressure deviations of the inlet and outlet are less than 5% under different inlet conditions, the model can be used.

[0088] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A hydrogen fuel cell stack fluid distribution simulation method that simplifies the computational difficulty, characterized in that: include: Based on the actual hydrogen fuel cell stack situation, the size of the common manifold is obtained, and based on the size of the common manifold, the size of the flow channel of the fuel cell is obtained, and then a three-dimensional geometric model or a two-dimensional geometric model of the hydrogen fuel cell stack is created as a simplified model; Based on the experimental data, determine the inlet boundary conditions and outlet boundary conditions of the fuel cell stack; Based on the 3D geometric model of the hydrogen fuel cell stack, create a geometric model of the stack fluid distribution; The viscous force term in the Brinkman equation based on porous media is used to simulate the local resistance loss caused by the geometric structure of the common manifold of the fuel cell stack to distribute the fluid. Through simulation, the local resistance loss coefficient is continuously adjusted to meet the requirements, and the local resistance loss coefficient of the common manifold of the fuel cell stack to distribute the fluid is determined; The resistance coefficient of the battery flow channel is determined by adjusting the inlet boundary conditions and outlet boundary conditions that are consistent with the actual conditions through experiments, and then the resistance coefficient of the battery flow channel is determined after the resistance coefficient of the battery flow channel is continuously adjusted to meet the requirements; The model is built, and the stack fluid distribution results are calculated through simulation; Before determining the local resistance loss coefficient at the common manifold of the stack where the fluid is distributed, the pressure loss at the common manifold of the stack is obtained according to the incompressible flow equation of the pipeline: Where ΔP is the pressure drop between the common manifolds of the stack, f is the friction coefficient, L is the flow path length, and D h is the hydraulic diameter, ρ is the fluid density, is the average velocity of the fluid, K L is the local resistance coefficient.

2. The hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty according to claim 1 is characterized in that: The flow channel cross-sectional size of the fuel cell in the three-dimensional geometric model or the two-dimensional geometric model of the hydrogen fuel cell stack is not less than 1 / A of the common manifold size, and the value of A is determined based on the convergence of the calculation and the calculation time.

3. The hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty according to claim 1, characterized in that: Based on the experimental data, the specific contents of the inlet boundary conditions and outlet boundary conditions of the fuel cell stack are determined as follows: The inlet volume flow rate and outlet volume flow rate of the fuel cell stack are obtained through experiments, and the volume flow rate conditions of the inlet manifold of the fuel cell stack are determined; the inlet and outlet pressures of the fuel cell stack are obtained through experiments, and the pressure boundary conditions of the outlet manifold of the fuel cell stack are determined.

4. The hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty according to claim 1, characterized in that: The specific contents of using porous media area to simulate the actual pressure drop of fuel cell flow channel and simulating the local resistance loss that affects the pressure drop between common manifolds of fuel cell stack are as follows: Based on the geometric model of fluid distribution in the battery stack, the geometric area where the fuel cell flow channel and the common manifold distribute fluid to the fuel cell flow channel is set as a porous media area. The set porous media area includes a first area representing the fuel cell flow channel and two second areas arranged on both sides of the first area and intersecting with the fuel cell flow channel and the common manifold flow channel. The porous media setting area of ​​the first area is used to simulate a realistic pressure drop in the simplified battery flow channel model, and the porous media setting areas of the two second areas are used to simulate the local resistance loss at the common manifold.

5. The hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty according to claim 4 is characterized in that: The resistance coefficient of the first region is achieved by setting the permeability and porosity, and the local resistance loss of the second region, which is proportional to the square of the velocity of the fluid, is simulated and determined by setting the porosity and the viscosity coefficient.

6. The hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty according to claim 5, characterized in that: The permeability and porosity of the first region are set based on the Brinkman equation, and its differential form is as follows: Where μ is the dynamic viscosity, k is the permeability of the porous medium, β is the viscosity coefficient of non-Darcy flow, u is the fluid velocity, F is the external force, P is the pressure, and Q is m is the mass source term, ε p is the porosity of the porous medium, I is the unit matrix; ρ is the fluid density, is the gradient operator, is the divergence operator, and T is the transposition operator; The first region simulates pressure losses without considering the viscous force option for non-Darcy flow.

7. The hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty according to claim 5, characterized in that: The local resistance loss in the second area is set by setting the porosity of the Brinkman equation to 1, when the permeability option does not exist, and adding the viscous force term of the non-Darcy flow to simulate the local resistance loss; the local resistance loss coefficient is determined by comparing and fitting the simulation calculations of two models with a common manifold to distribute the fluid and a simplified geometric structure.

8. The hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty according to claim 7, characterized in that: The specific contents of the determination of the local resistance loss coefficient through the simulation comparison fitting method are as follows: Create a simplified model corresponding to the real distribution manifold and a simplified model corresponding to the simplified distribution manifold. Given the same inlet boundary conditions and outlet boundary conditions for the two geometric models, adjust the model to the case where the flow rate allocated to each battery flow channel in the two models is the same. Then set the local resistance coefficient in the simplified model corresponding to the simplified distribution manifold, and continuously fit it with the flow calculation results of the real distribution manifold until the deviation between the common manifold pressure distribution of the simplified case and the real case is less than 5% under different inlet boundary conditions, and then determine the local resistance loss coefficient at this time.

9. The hydrogen fuel cell stack fluid distribution simulation method with simplified calculation difficulty according to claim 1, characterized in that: The specific content of determining the resistance coefficient of the battery flow channel is: In the simplified model, the previously determined local resistance loss coefficient is set, and the same inlet flow and outlet pressure boundary conditions are given to the simplified model and the experiment, and the resistance coefficient of the battery flow channel is continuously adjusted. If, under different inlet flow boundary conditions, the deviation between the simulated inlet and outlet pressure difference of the common manifold of the battery stack and the actual inlet and outlet pressure difference is less than 5%, it is determined that the resistance coefficient of the battery flow channel at this time has been adjusted, and then the resistance coefficient of the battery flow channel at this time is determined.

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