High-pressure gas leakage analysis method by coupling full-flow-rate leakage model with CFD (computational fluid dynamics) method

Abstract

The invention relates to a high-pressure gas leakage analysis method by coupling a full-flow-rate leakage model with a CFD method. The method comprises the following steps: modeling a high-pressure tritium gas storage tank and an environment where the high-pressure tritium gas storage tank is located; the leakage flow of a leakage opening of the tank body is calculated on the current time step, a CFD method is used for iteratively calculating a general conservation equation of fluid on each grid point in the leakage space, and diffusion and field distribution of the high-pressure tritium gas in the leakage space are obtained; the gas storage model is used for calculating non-isentropic heat transfer from the outside to the storage tank in the leakage process of the high-pressure tritium gas storage tank, and parameters in the tank body after leakage in the current time step are obtained; the updating time step reaches the set physical time scale, and the change of leakage parameters along with time after the high-pressure tritium gas storage tank leaks, the change of parameters in the storage tank along with time and the distribution of leaked tritium gas in the leakage space are obtained. Accurate estimation of the tritium gas leakage amount and detailed analysis of the tritium source item diffusion process are achieved, and effective support is provided for leakage accident emergency.

Description

Technical Field

[0001] This invention relates to the field of radiation nuclear emergency technology, and in particular to a high-pressure gas leakage analysis method that couples a full-flow-rate leakage model with a CFD method. Background Technology

[0002] Tritium's natural decay releases beta rays. Due to its strong penetrability and substitutability, tritium easily enters the human body through respiration or skin, and diffuses into bodily fluids by replacing hydrogen in the body's water, causing internal radiation exposure. Therefore, tritium is typically stored in high-pressure storage containers (on the order of 102 bar). Accidents such as impacts or drops can occur during storage, leading to tritium leaks. The tritium will be immediately released and diffuse into the environment, posing a radioactive hazard to personnel and the environment. Accurate prediction of the changes in stagnation parameters in the high-pressure container over time, as well as the flow rate and thermodynamic state of the leaking gas, is crucial for establishing accurate tritium leak models.

[0003] Current technologies for analyzing high-pressure gas leaks primarily focus on the amount of gas released, employing lumped parameter methods. These methods neglect the spatial distribution and temporal changes of the gas after it leaks into the external environment, failing to obtain effective data on the distribution of tritium source terms within the plant to support emergency response. Regarding prediction models, the thermodynamic state of high-pressure tank storage is primarily predicted by modifying the ideal gas state model. However, this prediction process often assumes an adiabatic leakage process that ignores heat transfer within the tank, leading to calculation errors in the thermodynamic state of high-pressure tritium. Furthermore, the leakage process only considers the critical sonic velocity flow, neglecting processes below the subcritical leakage velocity, a simplification that directly impacts the accurate calculation of the leakage amount.

[0004] In summary, for high-pressure tritium storage tank leakage accidents, to accurately assess the tritium source term, it is necessary not only to accurately estimate the leakage amount, but also to conduct a detailed analysis of the diffusion process of the tritium source term. There is a lack of corresponding technical solutions in the existing technology. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-pressure gas leakage analysis method that couples a full-flow-rate leakage model with a CFD method. This solves the technical problem that existing technologies cannot accurately estimate the amount of tritium leakage and lack detailed analysis of the diffusion process of the tritium source term, resulting in inaccurate assessment of the tritium source term and a lack of accurate data support for emergency response to leakage accidents.

[0006] The technical solution adopted in this invention is as follows: This invention provides a high-pressure gas leakage analysis method coupled with a full-flow-rate leakage model and a CFD method, comprising: Modeling of the high-pressure tritium storage tank and its environment includes dividing the computational domain into meshes for the tank leak outlet and the leak space, and discretizing the physical time of the leak into time steps; At the current time step, the leakage parameters of the tank are first calculated, including the leakage flow rate at the leak outlet; then, the general conservation equation of the fluid is iteratively calculated at each grid point in the leakage space using the CFD method to obtain the diffusion and field distribution of the leaked high-pressure tritium gas in the leakage space. Based on the leakage flow rate, the non-isentropic heat transfer from the outside to the tank during the leakage process of the high-pressure tritium storage tank is calculated using the gas storage model, and the internal parameters of the tank after the leakage at the current time step are obtained, including the temperature, pressure and specific volume of the tank. Update the current time step to the next time step and iterate until the set physical time scale is reached to obtain the changes of leakage parameters over time after the high-pressure tritium storage tank leaks, the changes of parameters inside the storage tank over time, and the distribution of leaked tritium in the leakage space. The calculation of the leakage flow includes: using a full-flow-rate leakage model for high-pressure storage tanks, the full-flow-rate process of leakage from critical jet to subcritical jet is calculated. The full-flow-rate leakage model for the high-pressure storage tank considers the process of high-pressure tritium gas leaking from the leak point to the outside of the tank as an isentropic and reversible process, and the calculation formula is as follows: in, Q m For leakage flow; C q is the flow coefficient, which is used to indicate the correction to the flow rate that takes into account the reduced flow area of ​​the leaking outlet due to viscosity; A The leakage area of ​​the storage tank; k The adiabatic coefficient; p This refers to gas pressure; a , b For van der Waals correction factors, respectively, are the molecular force correction term and the molecular specific volume correction term; v The gas specific volume is represented by the subscripts 0 and 1, which represent the upstream and downstream parameters of the leak, respectively.

[0007] The preferred technical solution is: The flow coefficient C q The calculation is performed using a correlation based on the leakage pressure difference, as shown in the following formula: in, For the back pressure at the leak point, The pressure upstream of the leak point is the tritium gas pressure inside the storage tank.

[0008] The calculation of the entire flow rate process from critical jet to subcritical jet for leakage in the high-pressure tritium storage tank includes: The jet state at the leak point is determined to be either an under-expanded high-speed jet or a fully expanded jet; Calculate the leakage flow rate by selecting the back pressure of the leak outlet that matches the identified jet state.

[0009] The jet state at the leak is determined based on whether the pressure ratio between the upstream and downstream reaches a critical pressure ratio, specifically according to the following formula: like Then the jet at the leak outlet is a sub-expanded high-speed jet, and we have: ; like Then the jet from the leak outlet is a fully expanding jet. ; in, m The critical pressure ratio is mentioned above; This is the back pressure at the leak point.

[0010] The gas storage model uses a closed-loop solution by combining the tank mass conservation equation, the tritium energy conservation equation, the actual gas state equation, the Helmholtz free energy enthalpy equation, and the Newtonian convective heat transfer formula to obtain the partial derivatives of density and enthalpy with pressure and temperature, as well as the changes in heat transfer of the tank over time. This allows the determination of the changes in temperature and pressure of the tank over time.

[0011] For the combined tank mass conservation equation and tritium energy conservation equation, the actual gas state equation and the Helmholtz free energy enthalpy equation are introduced to solve for the partial derivatives of density with pressure and temperature, as well as the partial derivatives of enthalpy with pressure and temperature.

[0012] For the combined tank mass conservation equation and tritium energy conservation equation, the Newtonian convective heat transfer formula is introduced to calculate the change of the tank heat transfer over time. The Newtonian convection heat transfer formula takes into account the absence of rapid tritium flow inside the tank, and therefore the heat transfer mode is the heat transfer caused by natural convection excluding forced convection. The calculation formula is as follows: in, Heat transfer to the tank Over time t Changes These represent the convective heat transfer coefficient, the outer surface area of ​​the high-pressure tritium storage tank, and the temperature difference between the inner wall temperature of the high-pressure tritium storage tank and the high-pressure tritium gas.

[0013] The convective heat transfer coefficient The calculations include: in, Ra The Rayleigh number is the inner wall number of the high-pressure tritium gas storage tank. λ f The thermal conductivity of high-pressure tritium gas; l This refers to the inner diameter of the high-pressure tritium gas storage tank.

[0014] The calculation of the Rayleigh number includes: in, ρ The density of high-pressure tritium gas is kg / m³. 3 ; β ρ is the volumetric thermal expansion coefficient of high-pressure tritium gas, 1 / K; g is the acceleration due to gravity, m / s². 2 ; Let K be the temperature difference between the inner wall of the high-pressure tritium storage tank and the high-pressure tritium gas. c p The specific heat at constant pressure of high-pressure tritium gas is J / (kg K); μ The dynamic viscosity of high-pressure tritium gas is given in Pa·s. λ The thermal conductivity is W / (mk).

[0015] The calculation of the temperature inside the storage tank includes the temperature of the inner wall of the storage tank. The calculation includes: in, For the heat flow between the environment and the high-pressure tritium storage tank, These are the mass of the high-pressure tritium storage tank wall and the specific heat capacity of the high-pressure tritium storage tank material, respectively.

[0016] The technical solution of the present invention can achieve at least some of the following beneficial effects: The high-pressure gas leakage analysis method of the present invention, which couples the full-flow-rate leakage model with CFD, uses a CFD coupling of a high-pressure storage tank full-flow-rate leakage model that considers the isentropic process assumption and corrects the actual gas state model equations, and a gas storage model of a non-isentropic high-pressure tritium storage tank that considers the heat transfer process. The two models are solved iteratively at each time step, and the calculation of the high-pressure tritium leakage process and the detailed analysis of the diffusion process of the leaked tritium in the storage tank plant are realized simultaneously, and the source term data that is effective for emergency response are finally obtained.

[0017] The leakage model of this invention can distinguish between under-expanded high-speed jets and fully expanded jets when calculating leakage flow rate, and can calculate the entire flow rate process of leakage in high-pressure tritium storage tanks from critical jets to subcritical jets, thereby improving the accuracy of leakage flow rate calculation results.

[0018] In the leakage model of this invention, the van der Waals equation of state for the actual gas state model equation of high-pressure tritium is corrected using the Sanville mass flow formula. This takes into account the effects of high-pressure intermolecular forces and molecular volume, and achieves a mechanistic correction of the gas property model of high-pressure tritium that deviates from that of an ideal gas. At the same time, the heat exchange effect between the storage tank and the outside environment during the leakage process is also taken into account, thus improving the accuracy of the model.

[0019] The gas storage model of this invention is based on the energy conservation of high-pressure tritium gas. It also introduces the actual gas equation of state considering the gas specific volume correction term, the enthalpy equation based on the Helmholtz free energy calculation method, and the Newtonian convection heat transfer formula based on the Nusselt number and Rayleigh number for closed-loop solution, which has high computational efficiency and accurate results. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the method of an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the high-pressure tritium gas storage tank and its surrounding environment according to an embodiment of the present invention. Detailed Implementation

[0022] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0023] See Figure 1 This embodiment of a high-pressure gas leakage analysis method using a full-flow-rate leakage model coupled with CFD (Computational Fluid Dynamics) includes: S1. Model the high-pressure tritium storage tank and its surrounding environment, including dividing the computational domain into meshes for the tank leak outlet and the leak space, and discretizing the physical time of the leak into time steps.

[0024] Specifically, the modeling structure of the high-pressure tritium storage tank and its surrounding environment in this embodiment can be found in [reference needed]. Figure 2 The high-pressure tritium storage tank is located inside the plant building (i.e., the leak space), and the high-pressure tritium leaks into the plant environment from the leak port of the storage tank.

[0025] Specifically, the computational domain mesh should meet the requirements of high-velocity simulation analysis of tritium gas at the leak location, and independence verification should be performed. Physical time discretization should be combined with practical needs and experience, and time step independence verification should be implemented.

[0026] S2. At the current time step, the leakage parameters of the tank are first calculated, including the leakage flow rate at the leak outlet; then, the general conservation equations of the fluid are iteratively calculated at each grid point in the leakage space using the CFD method, including: mass conservation equation, momentum conservation equation, energy conservation equation and multi-component transport equation. After the iterative calculation is completed, the diffusion and field distribution of the leaked high-pressure tritium gas in the leakage space are obtained.

[0027] As a preferred method, the calculation of the leakage flow includes: using a full-velocity leakage model for high-pressure storage tanks to calculate the full-velocity process of leakage from critical jet (underexpanded high-speed jet) to subcritical jet (fully expanded jet) in high-pressure tritium storage tanks.

[0028] Specifically, the leakage model constructed in this embodiment is a full-velocity leakage model for high-pressure storage tanks that considers the process of high-pressure tritium gas leaking from the leak outlet to the outside of the storage tank as an isentropic reversible process and has been modified according to the actual gas state model equations, in order to calculate the leakage flow rate after a high-pressure tritium gas storage tank leakage accident. Q m The calculation formula for the leakage model is as follows: in, Q m Leakage flow rate, kg / s; C q is the flow coefficient, which is used to indicate the correction to the flow rate that takes into account the reduced flow area of ​​the leaking outlet due to viscosity; A The leakage area of ​​the storage tank is in meters. 2 ; k The adiabatic coefficient; p This refers to gas pressure; a , b For van der Waals correction factors, respectively, are the molecular force correction term and the molecular specific volume correction term; v For the specific volume of the gas, m 3 / kg; subscripts 0 and 1 represent upstream and downstream parameters of the leak, respectively, for example... The pressure upstream of the leak point, i.e., the tritium gas pressure inside the storage tank, is expressed in Pa. Let be the pressure downstream of the leak, in Pa. The specific volume of gas upstream of the leak point is the specific volume of tritium gas inside the storage tank. The specific volume of tritium gas downstream of the leak point.

[0029] Specifically, the flow coefficient C q The calculation is performed using a correlation based on the leakage pressure difference, as shown in the following formula: in, For the back pressure at the leak point, The pressure upstream of the leak point is the tritium gas pressure inside the storage tank.

[0030] Specifically, the leakage model is obtained by modifying the Sanville mass flow rate formula using the van der Waals equation of state, wherein the Sanville mass flow rate formula is as follows: The meanings of the symbols in the formula are explained above.

[0031] The preferred van der Waals equation of state is the actual gas correction method of the high-pressure tritium equation of state, which can simultaneously consider the effects of intermolecular forces and molecular volume, as shown in the following equation: The meanings of the symbols in the formula are explained above: a , b These are the molecular force correction term and the molecular specific volume correction term, which are dimensionless; T The temperature of tritium gas is K; p The pressure of tritium gas is Pa. R g is the ideal gas constant.

[0032] Specifically, the calculation methods for the molecular interaction force correction term and the molecular specific volume correction term are as follows: in, P c The critical pressure is given in Pa. T c Let K be the critical temperature.

[0033] Specifically, the leakage model calculates the critical and subcritical sound velocity leakage processes of high-pressure tritium storage tanks across the entire flow velocity range, including: The jet state at the leak point is determined to be either an under-expanded high-speed jet or a fully expanded jet; Calculate the leakage flow rate by selecting the back pressure of the leak outlet that matches the identified jet state.

[0034] Specifically, the jet state at the leak is determined based on whether the pressure ratio between the upstream and downstream reaches a critical pressure ratio, according to the following formula: like Then the jet at the leak outlet is a sub-expanded high-speed jet, and we have: ; like Then the jet from the leak outlet is a fully expanding jet. ; in, For the back pressure at the leak point, m The critical pressure ratio is calculated as follows: .

[0035] S3. Based on the leakage flow rate, use the gas storage model to calculate the non-isentropic heat transfer from the outside to the tank during the leakage process of the high-pressure tritium gas storage tank, and obtain the internal parameters of the tank after the leakage at the current time step, including the temperature, pressure and specific volume of the tank.

[0036] The gas storage model uses a closed-loop solution by combining the tank mass conservation equation, the tritium energy conservation equation, the actual gas state equation, the Helmholtz free energy enthalpy equation, and the Newtonian convective heat transfer formula to obtain the partial derivatives of density and enthalpy with pressure and temperature, as well as the changes in heat transfer of the tank over time, and then obtains the changes in temperature and pressure of the tank over time.

[0037] Specifically, the construction of the gas storage model includes: (1) According to the mass conservation equation, the mass of the gas inside the tank m over time t rate of change equal to volume V Multiply density ρ rate of change over time ,Right now: and The leakage flow rate can be directly calculated based on the leakage model.

[0038] (2) According to the energy conservation law of high-pressure tritium gas in the storage tank: internal energy + kinetic energy + potential energy = heat exchange between the gas in the storage tank and the surrounding environment + enthalpy of inflow - enthalpy of outflow, the following equation exists: in, The heat exchange amount, It is the enthalpy value at the outlet of the high-pressure storage tank. The enthalpy of tritium in the high-pressure storage tank at the moment of leakage. The leakage mass flow rate of tritium in the high-pressure storage tank. For a moment.

[0039] The simultaneous equations for the conservation of mass in the storage tank and the energy conservation equation for tritium are as follows: To obtain the changes in temperature and pressure of the tank over time according to the above formula, the values ​​of the following parameters are needed: , , , , , , , ;in, , , As can be seen from step (1), for a known quantity, the density is a partial derivative with respect to pressure and temperature. , Enthalpy as a function of pressure and temperature , and the change in heat transfer of the tank over time. The quantity that needs to be solved.

[0040] (3) Based on the tank mass conservation equation and tritium energy conservation equation established in step (2), the actual gas state equation and the Helmholtz free energy enthalpy equation are introduced to solve for the partial derivatives of density with respect to pressure and temperature, as well as the partial derivatives of enthalpy with respect to pressure and temperature. Specifically, this includes: The real gas equation of state In the formula, p , v These are the pressure and specific volume of the high-pressure tritium in the storage tank, respectively. R g Let be the ideal gas constant. T The temperature of the high-pressure tritium in the storage tank; b The preferred value for the volume correction term is 0.0077.

[0041] The equation based on Helmholtz free energy enthalpy: In the formula, h The enthalpy of high-pressure tritium gas inside the storage tank; R g It is the ideal gas constant; Density of high-pressure tritium gas inside the storage tank; T The temperature of the high-pressure tritium gas inside the storage tank; This is the ratio of the critical temperature of tritium to the temperature inside the storage tank. The contribution of an ideal gas to the reduction in Helmholtz free energy. The remaining contribution of the ideal gas to the reduced Helmholtz free energy, This is an empirical constant; specific values ​​can be found in relevant technical manuals.

[0042] (4) Based on step (3), the Newtonian convection heat transfer formula is further introduced to calculate the change of heat transfer in the tank over time.

[0043] Preferably, the Newtonian convection heat transfer formula considers the absence of rapid tritium flow inside the tank, thus the heat transfer mode is the heat transfer caused by natural convection excluding forced convection, and the calculation formula is as follows: in, Heat transfer to the tank Over time t Changes, These are the convective heat transfer coefficient, the outer surface area of ​​the high-pressure tritium storage tank, the inner wall temperature of the high-pressure tritium storage tank, and the temperature difference between the high-pressure tritium gas and the inner wall temperature.

[0044] The convective heat transfer coefficient The calculations include: in, Ra The Rayleigh number is the inner wall number of the high-pressure tritium gas storage tank. λ f is the thermal conductivity of high-pressure tritium gas, W / (m K); l denoted as the inner diameter of the high-pressure tritium gas storage tank, in meters (m).

[0045] The calculation of the Rayleigh number includes: In the formula, ρ The density of high-pressure tritium gas is kg / m³. 3 ; β ρ is the volumetric thermal expansion coefficient of high-pressure tritium gas, 1 / K; g is the acceleration due to gravity, m / s². 2 ; Let K be the temperature difference between the inner wall of the high-pressure tritium storage tank and the high-pressure tritium gas. c p The specific heat at constant pressure of high-pressure tritium gas is J / (kg K); μ The dynamic viscosity of high-pressure tritium gas is given in Pa·s. λ is the thermal conductivity, W / (m K).

[0046] Specifically, the inner wall temperature of the high-pressure tritium gas T w The solution requires knowing the initial high-pressure tritium inner wall temperature, and then gradually calculating the inner wall temperature at the next moment by using the rate of change for each time interval. The calculation method includes: in, For the heat flow between the environment and the high-pressure tritium storage tank, These are the mass of the high-pressure tritium storage tank wall and the specific heat capacity of the high-pressure tritium storage tank material, respectively.

[0047] Specifically, the inner wall temperature of the high-pressure tritium gas can be considered as a constant value of the ambient temperature, i.e., 300K, during the calculation process.

[0048] S4. Update the current time step to the next time step and iterate. Repeat S2 to S4 until the set physical time scale is reached to obtain the changes of leakage parameters over time after the high-pressure tritium storage tank leaks, the changes of parameters inside the storage tank over time, and the distribution of leaked tritium in the leakage space.

[0049] Specifically, the input parameters required for the calculation process in steps S2-S4 need to use the updated parameters from the previous time step, and if it is the initial time step, the initial conditions are used.

[0050] In summary, the high-pressure gas leakage analysis method coupled with a full-flow-rate leakage model and a CFD method in this embodiment can iteratively solve the diffusion process of high-pressure tritium gas leaking into the high-pressure storage tank building at multiple grid nodes over time steps, thereby enabling refined spatiotemporal distribution analysis. Specifically, it employs a CFD-coupled high-pressure storage tank full-flow-rate leakage model that considers the isentropic process assumption and modifies the actual gas state model equations, and a non-isentropic high-pressure tritium gas storage tank gas storage model that considers the heat transfer process. At each time step, iteratively solving both models calculates the high-pressure tritium gas leakage process, simultaneously achieving both the calculation of the high-pressure tritium gas leakage process and a refined analysis of the diffusion process of leaked tritium gas within the storage tank building, ultimately obtaining source term data effective for emergency response.

[0051] It will be understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-pressure gas leakage analysis method coupled with a full-flow-rate leakage model and a CFD method, characterized in that, include: Modeling of the high-pressure tritium storage tank and its environment includes dividing the computational domain into meshes for the tank leak outlet and the leak space, and discretizing the physical time of the leak into time steps; At the current time step, the leakage parameters of the tank are first calculated, including the leakage flow rate at the leak outlet; then, the general conservation equation of the fluid is iteratively calculated at each grid point in the leakage space using the CFD method to obtain the diffusion and field distribution of the leaked high-pressure tritium gas in the leakage space. Based on the leakage flow rate, the non-isentropic heat transfer from the outside to the tank during the leakage process of the high-pressure tritium storage tank is calculated using the gas storage model, and the internal parameters of the tank after the leakage at the current time step are obtained, including the temperature, pressure and specific volume of the tank. Update the current time step to the next time step and iterate until the set physical time scale is reached to obtain the changes of leakage parameters over time after the high-pressure tritium storage tank leaks, the changes of parameters inside the storage tank over time, and the distribution of leaked tritium in the leakage space. The calculation of the leakage flow includes: using a full-flow-rate leakage model for high-pressure storage tanks, the full-flow-rate process of leakage from critical jet to subcritical jet in high-pressure tritium storage tanks is calculated. The full-flow-rate leakage model for the high-pressure storage tank considers the process of high-pressure tritium gas leaking from the leak point to the outside of the tank as an isentropic and reversible process, and the calculation formula is as follows: in, Q m For leakage flow; C q is the flow coefficient, which is used to indicate the correction to the flow rate that takes into account the reduced flow area of ​​the leaking outlet due to viscosity; A The leakage area of ​​the storage tank; k The adiabatic coefficient; p This refers to gas pressure; a , b For van der Waals correction factors, respectively, are the molecular force correction term and the molecular specific volume correction term; v The gas specific volume is represented by the subscripts 0 and 1, which represent the upstream and downstream parameters of the leak, respectively.

2. The method according to claim 1, characterized in that, The flow coefficient C q The calculation is performed using a correlation based on the leakage pressure difference, as shown in the following formula: in, For the back pressure at the leak point, The pressure upstream of the leak point is the tritium gas pressure inside the storage tank.

3. The method according to claim 1, characterized in that, The calculation of the entire flow rate process from critical jet to subcritical jet for leakage in the high-pressure tritium storage tank includes: The jet state at the leak point is determined to be either an under-expanded high-speed jet or a fully expanded jet; Calculate the leakage flow rate by selecting the back pressure of the leak outlet that matches the identified jet state.

4. The method according to claim 3, characterized in that, The jet state at the leak is determined based on whether the pressure ratio between the upstream and downstream reaches a critical pressure ratio, specifically according to the following formula: like Then the jet at the leak outlet is a sub-expanded high-speed jet, and we have: ； like Then the jet from the leak outlet is a fully expanding jet. ; in, m The critical pressure ratio is mentioned above; This is the back pressure at the leak point.

5. The method according to claim 1, characterized in that, The gas storage model uses a closed-loop solution by combining the tank mass conservation equation, the tritium energy conservation equation, the actual gas state equation, the Helmholtz free energy enthalpy equation, and the Newtonian convective heat transfer formula to obtain the partial derivatives of density and enthalpy with pressure and temperature, as well as the changes in heat transfer of the tank over time. This allows the determination of the changes in temperature and pressure of the tank over time.

6. The method according to claim 5, characterized in that, For the combined tank mass conservation equation and tritium energy conservation equation, the actual gas state equation and the Helmholtz free energy enthalpy equation are introduced to solve for the partial derivatives of density with pressure and temperature, as well as the partial derivatives of enthalpy with pressure and temperature.

7. The method according to claim 5, characterized in that, For the combined tank mass conservation equation and tritium energy conservation equation, the Newtonian convective heat transfer formula is introduced to calculate the change of the tank heat transfer over time. The Newtonian convection heat transfer formula takes into account the absence of rapid tritium flow inside the tank, and therefore the heat transfer mode is the heat transfer caused by natural convection excluding forced convection. The calculation formula is as follows: in, Heat transfer to the tank Over time t Changes These represent the convective heat transfer coefficient, the outer surface area of ​​the high-pressure tritium storage tank, and the temperature difference between the inner wall temperature of the high-pressure tritium storage tank and the high-pressure tritium gas.

8. The method according to claim 7, characterized in that, The convective heat transfer coefficient The calculations include: in, Ra The Rayleigh number is the inner wall number of the high-pressure tritium gas storage tank. λ f The thermal conductivity of high-pressure tritium gas; l This refers to the inner diameter of the high-pressure tritium gas storage tank.

9. The method according to claim 7, characterized in that, The calculation of the Rayleigh number includes: in, ρ The density of high-pressure tritium gas; β ρ is the coefficient of volumetric thermal expansion of high-pressure tritium; g is the acceleration due to gravity; This refers to the temperature difference between the inner wall of the high-pressure tritium storage tank and the high-pressure tritium gas. c p The specific heat at constant pressure of high-pressure tritium gas; μ The dynamic viscosity of high-pressure tritium gas; λ is the thermal conductivity.

10. The method according to claim 7, characterized in that, The calculation of the temperature inside the storage tank includes the temperature of the inner wall of the storage tank. The calculation includes: in, For the heat flow between the environment and the high-pressure tritium storage tank, These are the mass of the high-pressure tritium storage tank wall and the specific heat capacity of the high-pressure tritium storage tank material, respectively.

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