Tunnel hydrogen energy vehicle leakage and explosion risk prediction and automatic ventilation emergency disposal method

Abstract

The invention discloses a tunnel hydrogen energy vehicle leakage and explosion risk prediction and automatic ventilation emergency disposal method, and belongs to the technical field of hydrogen leakage accident risk prediction and emergency disposal. According to the method, the potential leakage point of each component is determined by obtaining hydrogen-related component information of the hydrogen fuel cell vehicle. An accident tree is used to identify a root cause that may cause hydrogen leakage in the system, and then different accident scenarios are defined. And according to the leakage scenes of different hydrogen-related parts, determining the leakage frequency and the complete fracture frequency, and determining the disaster category. And finally, according to the leakage probability, the ignition probability and the consequences of different accident situations, calculating the comprehensive probability of disaster occurrence. And in combination with a hydrogen concentration sensor array arranged in the tunnel, the longitudinal ventilation air speed and the transverse exhaust air rate are automatically analyzed and adjusted, and the optimal economical, safe and efficient combined ventilation array is obtained according to risk indexes. The method can effectively predict the disaster-pregnant risk of the hydrogen storage vehicle in different environments, provides an economic and safe emergency disposal scheme, and can provide a theoretical basis for the safety technology development of a hydrogen storage system.

Description

Technical Field

[0001] The present invention relates to the technical fields of risk prediction and emergency disposal, and specifically provides a risk prediction method for the safety of personnel in the event of a leakage and explosion accident of an in-vehicle high-pressure hydrogen storage system in a tunnel based on the HyRAM platform, supplemented by a ventilation emergency disposal technology with a cross arrangement of longitudinal ventilation and transverse ventilation. Background Art

[0002] In an open space, due to its small density and fast diffusion speed, hydrogen is difficult to form a combustible hydrogen cloud mass of a certain scale. Compared with an open space, a semi-closed space such as a tunnel not only restricts the diffusion of hydrogen, but also has a reflection enhancement effect on the overpressure wave after the cloud mass is ignited. In the future, vehicles carrying high-pressure hydrogen storage systems will surely become an important carrier of transportation. Therefore, potential hydrogen leakage-diffusion-explosion accidents of high-pressure hydrogen storage systems under confined space conditions seriously threaten the personal safety of the personnel on the accident vehicle and the rescue personnel. In addition, the potential safety hazards of high-pressure hydrogen storage systems have also become an important factor restricting the popularization of hydrogen energy in transportation.

[0003] Through research, it is found that the current mainstream methods for predicting the leakage risk of high-pressure hydrogen storage systems are FMEA failure mode analysis, HAZOP hazard and operability study, and simple fault tree analysis. The detonation risk of high-pressure hydrogen storage systems is mainly analyzed by models such as QRA, TNT, BST, and TNO multi-energy method. Most of the existing research on hydrogen fuel cell vehicle leakage and explosion accidents focuses on using temperature and overpressure to determine the accident consequences and scale, lacking further information and evaluation on individual risk and social risk. On the other hand, there is a fragmentation between the prediction method for the leakage risk of high-pressure hydrogen storage systems and the prediction method for the detonation risk of high-pressure hydrogen storage systems.

[0004] In addition, the ventilation emergency disposal technology mainly based on longitudinal ventilation is the main means to deal with toxic and harmful gas leakage accidents in tunnels. However, due to the closed nature of the tunnel, a relatively small longitudinal ventilation speed is difficult to dilute the leaked hydrogen cloud in a short time, while a relatively large longitudinal ventilation speed will bring huge costs. Another common ventilation method is transverse exhaust. Due to the narrow exhaust duct, transverse exhaust will also bring the problem of hydrogen accumulation in the smoke exhaust duct while discharging hydrogen. Therefore, a single ventilation method has defects, and there is an urgent need to reasonably set up an emergency disposal plan with multiple ventilation methods cooperating with each other. Summary of the Invention

[0005] The purpose of the present invention is to provide, based on a high-pressure hydrogen storage system, a risk prediction method that can comprehensively consider the occurrence frequency of leakage accidents and the hazards of detonation overpressure temperature in view of the deficiencies of existing risk prediction methods and emergency disposal technologies, and provide an economical, safe and efficient hydrogen control-exhaust combined ventilation emergency disposal plan for the hydrogen that is likely to accumulate in tunnels.

[0006] The technical solution adopted by the present invention is as follows: A method for predicting the leakage, combustion and explosion risks of hydrogen energy vehicles in tunnels and automatically ventilating and emergency disposing, comprising the following steps:

[0007] S1. Analyze the on-vehicle high-pressure hydrogen storage system, classify and mark the potential leakage points; based on the classified and marked potential leakage points, identify various fault modes of hydrogen fuel cell vehicles in the tunnel, and analyze the possible fault types of each component; define different accident scenarios through a fault tree, and clarify the relevant fault types and their consequences occurring in each accident scenario;

[0008] S2. Determine the leakage frequency and complete rupture frequency according to the leakage scenarios of different hydrogen-related components; when calculating the leakage frequency, correspond the leakage aperture according to the hydrogen storage pressure and hydrogen storage volume to obtain the leakage frequency;

[0009] S3. Analyze the potential leakage points and leakage forms of the on-vehicle high-pressure hydrogen storage system under different accident scenarios;

[0010] The leakage forms caused by the leakage points are divided into: instantaneous leakage and continuous leakage; calculate the hydrogen mass rate curves under different leakage forms:

[0011] For the instantaneous leakage accident, the difference in the mass before and after the storage tank is used to obtain the mass of the leaked hydrogen;

[0012] For the continuous leakage accident, when the leaked hydrogen with a leakage pressure below 10 MPa is processed using the ideal gas state equation to calculate the hydrogen mass rate curve; when the leakage pressure is greater than 10 MPa, the Abel-Noble state equation is used to process and calculate the hydrogen mass rate curve;

[0013] S4. Construct a comprehensive disaster occurrence probability model; establish an instant ignition and delayed ignition two-dimensional evaluation system through the HyRAM model and the HYEX model, and the disaster forms are: unignited, jet fire, flash fire and explosion; based on the fault tree analysis method, integrate the probability distribution of the leakage rate, the spatio-temporal distribution characteristics of the ignition source and the multi-disaster coupling coefficient, and finally calculate the comprehensive risk probability of the disaster chain;

[0014] S5. Based on the disaster consequences, combine the overpressure hazard model and the temperature hazard model, and evaluate the accident risk according to the fatality rate and the influence range of personnel; summarize the risk data of the accident scenarios, and combine the leakage probability, the ignition probability and the accident consequences to obtain the combustion and explosion risk prediction model of the tunnel high-pressure hydrogen storage system;

[0015] S6. Based on the consequences of multiple accident scenarios of hydrogen leakage accidents, through numerical simulation, a longitudinal ventilation array that penetrates the tunnel is set up by jet fans, and a transverse exhaust port array with equal spacing is symmetrically arranged above the leaking vehicle with the leakage source as the center; among them, the transverse exhaust ports maintain a constant spacing, and the exhaust air volume is used as a control variable; the longitudinal ventilation array and the transverse ventilation array are cross-combined to form a ventilation array matrix; through a hydrogen leakage risk assessment system composed of a hydrogen concentration sensor and a computer, the risk of the on-vehicle high-pressure hydrogen storage system in the tunnel under emergency disposal technologies is compared, and the optimal economic, safe and efficient combined ventilation emergency disposal plan is obtained with the specified risk weight as the evaluation index.

[0016] Further, in step S1, the leakage points of the on-vehicle high-pressure hydrogen storage system include valves, instruments, nodes, pipelines, and storage tanks.

[0017] Further, in step S2, the annual frequency of hydrogen leakage includes leakage conditions of different sizes, and the leakage sizes include 0.01%, 0.1%, 1%, 10%, 100%; the leakage frequency of a single component is calculated according to the fatigue usage degree of the component.

[0018] In HyRAM, the leakage size is represented by k, and the formula for calculating the annual frequency of hydrogen leakage with a leakage size of 100% is:

[0019]

[0020] For leakage sizes other than 100%, the formula for calculating the annual frequency of hydrogen leakage is:

[0021]

[0022]

[0023] is the potential leakage point in the on-vehicle high-pressure hydrogen storage system. is the average leakage rate when the leakage size of component i is k. is .

[0024] Further, in step S3, the hydrogen mass rate curve in the continuous leakage form is calculated, specifically:

[0025] The ideal gas state equation judges the flow state of hydrogen according to the relationship between the initial pressure of the leaked hydrogen and the ambient pressure.

[0026] When the relationship between the initial pressure of hydrogen leakage and the ambient pressure satisfies the following formula, the hydrogen leakage is in a supersonic flow state; the outlet pressure of the leakage port is the critical pressure, and the leakage velocity is the local sound velocity of hydrogen.

[0027]

[0028] At this time, the mass formula of the leaked hydrogen is:

[0029]

[0030] When the relationship between the initial pressure of hydrogen leakage and the ambient pressure satisfies the following formula, the hydrogen leakage is in a subsonic flow state; the outlet pressure of the leakage port is the ambient pressure, and the leakage velocity is lower than the local speed of sound;

[0031]

[0032] At this time, the mass formula of the leaked hydrogen is:

[0033]

[0034] In the formula, p0 is the ambient pressure; p is the initial pressure; κ is the gas adiabatic index; Q is the hydrogen leakage rate, kg / s; C d is the gas leakage coefficient; A is the leakage port area; M is the gas molar mass; R is the gas constant; T is the temperature;

[0035] Calculation process of the Abel-Noble equation of state:

[0036]

[0037] From the mass conservation equation and the energy conservation equation, we get:

[0038]

[0039]

[0040] The density of hydrogen at the actual leakage outlet:

[0041]

[0042] The leakage velocity formula of hydrogen at the actual leakage outlet:

[0043]

[0044] The hydrogen leakage rate formula:

[0045]

[0046] In the formula, ρ1 is the initial hydrogen density, kg / m 3 ; p1 is the initial pressure, Pa; b is the Abel-Noble residual volume coefficient; R H2 is the hydrogen gas constant, taking 4.124×103 J / (kg·K); T1 is the initial temperature, K; κ is the adiabatic index; ρ3 is the hydrogen density at the actual leakage port, kg / m3 ; T3 is the temperature of the actual leakage port, in K; p3 is the pressure of the actual leakage port, in Pa; u3 is the leakage velocity of the actual leakage port, in m / s; Q is the mass leakage flow rate, in kg / s; A is the area of the leakage port, in m 2 .

[0047] Further, in the step S4, the probability calculation method:

[0048]

[0049]

[0050]

[0051]

[0052] where is the annual frequency of event x, is the occurrence probability of event x.

[0053] Further, in the step S5, the disaster consequence is measured by using the individual risk probability, that is, the fatality probability within a unit of a specific location:

[0054]

[0055] where is the fatality probability, Y is the probability unit model, is the normal cumulative distribution function;

[0056] The temperature hazard model adopts the hazard degree of thermal radiation, that is, the thermal dose unit, expressed as a function of the heat flux intensity and the exposure time; the calculation of the thermal dose unit:

[0057]

[0058] In the formula, I is the radiant heat flux intensity, and t is the exposure duration;

[0059] The overpressure hazard model adopts the overpressure-impulse criterion. The overpressure hazard is divided into human lung injury, head injury, and body injury. The corresponding fatality probability calculations for each part are:

[0060]

[0061]

[0062]

[0063] In the formula, m is the mass of the injured person in the explosion scenario, P is the pressure, and I is the impulse.

[0064] Further, in step S6, the hydrogen leakage risk assessment system is as follows:

[0065] An array of hydrogen concentration sensors is arranged at equal intervals along the longitudinal direction of the tunnel on the ceiling to obtain the information of the accumulated hydrogen concentration; hydrogen concentration sensors are also arranged at equal intervals at the axial positions of the vertical exhaust vents within a radius of 20 m from the leakage point to monitor the hydrogen concentration in the exhaust duct; 4% hydrogen concentration is used as the hydrogen perception for leakage accidents, and the longitudinal ventilation array is used to reduce the hydrogen concentration on the ceiling, supplemented by transverse ventilation to control the hydrogen accumulated on the ceiling within a radius of 20 m from the leakage point.

[0066] The data of the hydrogen concentration sensors is transmitted to the computer. For each sensor arranged longitudinally on the tunnel ceiling, its corresponding row and column indexes are matched according to the coordinates where it is installed, and the transmitted data is stored in the corresponding row and column in the data matrix; it is set that when the hydrogen concentration is equal to 0, the system will default to the standby state, and when the hydrogen concentration is greater than 0, the value fed back by the sensor to the computer is 1, activating the system.

[0067] Further, the front of the hydrogen combustible cloud is subject to the transverse exhaust air volume, and the height of the deflagration risk is subject to the longitudinal ventilation speed; a ventilation plan matrix composed of different transverse exhaust air volumes and longitudinal ventilation speeds is constructed, with the transverse exhaust air volume controlled at 30 - 150 m 3 / s and the longitudinal ventilation speed controlled at 1 - 5 m / s.

[0068] Further, after the hydrogen leakage accident occurs, the computer will refresh the data matrix in real time and check the hydrogen concentration in sequence according to the ventilation direction. Among them, the hydrogen concentration at the sensor at the i-th row and j-th column is: h i,j ; if in the detected row, the maximum hydrogen concentration is greater than or equal to 4% and the concentration in the next row is less than 4% at the same time, then the position of this row is defined as the front of the hydrogen combustible cloud.

[0069] Further, for the hydrogen concentration sensor system vertically arranged in the axis of the exhaust duct, it will receive information feedback after the longitudinal ventilation system is activated; a data column is constructed according to its longitudinal coordinates, and the hydrogen concentration is detected in sequence from bottom to top according to the height. Among them, the hydrogen concentration at the k-th row is: h k ; if the hydrogen concentration in the detected row is greater than or equal to 8% and the hydrogen concentration in the next row is less than 8%, then the position of this row is defined as the height of the deflagration risk.

[0070] A tunnel hydrogen energy vehicle leakage deflagration risk prediction and automatic ventilation emergency disposal system, which includes a high-pressure hydrogen storage system, a leakage fault tree, a leakage model, an ignition probability model, a comprehensive disaster occurrence probability model, an overpressure damage model, a temperature damage model, a combined ventilation plan, and a hydrogen storage system leakage deflagration risk prediction model;

[0071] The high-pressure hydrogen storage system includes a hydrogen storage unit and a hydrogen fuel cell. Four hydrogen storage units are connected in parallel to form a unit group, and two unit groups are connected in series with the hydrogen fuel cell system to form the high-pressure hydrogen storage system. The leakage model includes a virtual nozzle model applicable to leakage pressures greater than 10 MPa, which consists of the Abel-Noble equation of state, and an ideal gas leakage model applicable to leakage pressures less than or equal to 10 MPa, which consists of the ideal gas equation of state. The comprehensive disaster occurrence probability model includes a hydrogen leakage annual frequency model, a leakage isolation model before ignition, and an ignition probability model. The combined ventilation plan includes a longitudinal ventilation plan and a transverse ventilation plan.

[0072] The hydrogen storage unit contains a total of 8 valves, including a main switch valve, a manual stop valve, a check valve, a drain needle valve, a solenoid valve, a pressure reducing valve, and a safety valve. In this system, a temperature-driven pressure relief device that may cause hydrogen release due to heat release or malfunction is classified as a valve. Considering the number of components in the hydrogen storage unit, the total number of components in the leakage fault tree of the hydrogen storage system is calculated.

[0073] The ignition probability model includes a delayed ignition probability model and an immediate ignition probability model.

[0074] Furthermore, a method for predicting the leakage, combustion, and explosion risk of a hydrogen energy vehicle in a tunnel and automatically ventilating for emergency disposal includes the following steps:

[0075] 1. Obtain the hydrogen-related component information of the hydrogen fuel cell vehicle, including the technical parameters of the hydrogen storage tank, high-pressure pipeline, low-pressure distribution pipeline, fuel cell unit, etc., such as volume, flow rate, pressure grade, etc. Determine the potential leakage points of each component, such as pipe joints, valves, hydrogen storage tanks, etc. Identify the types of faults that may be caused by the potential leakage points of various components through the leakage fault tree, and determine the corresponding leakage scenarios and leakage forms.

[0076] 2. Determine the leakage frequency and complete rupture frequency according to the leakage scenarios of different hydrogen-related components. Combine the obtained technical parameters and statistical quantities of the hydrogen-related components to obtain the overall leakage accident occurrence frequency of the hydrogen storage system. When calculating the leakage frequency, the leakage frequency corresponding to the leakage aperture (i.e., 0.01%, 0.1%, 1%, 10%, and 100% cross-sectional percentages) should be calculated according to the hydrogen storage pressure and hydrogen storage volume, and the total frequency should be calculated.

[0077] 3. Based on the determined leakage forms (i.e., instantaneous leakage, continuous leakage), construct the corresponding leakage models to obtain the hydrogen mass leakage rate curve. This is to identify the disaster consequences in different leakage scenarios in the subsequent calculation of the ignition probability model. When calculating the leakage curve, the corresponding leakage equation should be determined according to the initial leakage pressure.

[0078] 4. Different scenarios after hydrogen leakage are established. Based on the ignition probability model (the ignition probability model directly selects or modifies the HyRAM model and the HYEX model), by analyzing whether it ignites immediately or is delayed in ignition, the disaster categories are determined, including isolation, jet fire, deflagration, and explosion (including the expansion physical explosion caused by the rupture of the storage tank. It is necessary to discuss whether this type of container has catastrophic failures during extensive testing, such as the catastrophic rupture of the storage tank caused by impact). Then, according to the leakage probability, ignition probability, and the consequences of different accident scenarios, the comprehensive probability of the disaster occurrence is calculated.

[0079] 5. Based on the consequences of different disaster accidents obtained from the analysis, by using the overpressure hazard model and the temperature hazard model, the accident risk is evaluated according to the fatality rate of personnel and the influence range. Combining the occurrence probabilities of various corresponding disaster accidents, a risk prediction method for the on-vehicle high-pressure hydrogen storage system in the tunnel is obtained.

[0080] 6. Based on different scenarios after hydrogen leakage, jet fans with a wind speed of 1 m / s to 5 m / s are arranged to form a variety of longitudinal ventilations running through the tunnel, and exhaust vents with equal spacing are symmetrically arranged above the leaking vehicle with the leakage point as the center to form a transverse ventilation array. The transverse exhaust vents are controlled to maintain a constant spacing and the exhaust air volume as the main control variables. The longitudinal ventilation array and the transverse ventilation array are cross-combined to form a ventilation array matrix. Through the hydrogen leakage risk assessment system composed of hydrogen concentration sensors and computers, the risks of the on-vehicle high-pressure hydrogen storage system in the tunnel under emergency disposal technologies are compared, and the optimal combined ventilation emergency disposal plan with economic safety and high efficiency is obtained with the specified risk weight as the evaluation index.

[0081] Compared with the prior art, the present invention has the following advantages:

[0082] 1. The considered leakage methods are diverse and objective. Starting from different leakage apertures and taking the annual leakage frequency of components as the basis, the leakage rate is defined for the potential leakage points of each component, increasing the objectivity of the leakage accident analysis.

[0083] 2. The ignition model is combined with the leakage probability model, correlating the leakage risk and the combustion and explosion risks of the high-pressure hydrogen storage system. The spatial and temporal distributions of the disaster-forming process of the high-pressure hydrogen storage system in the tunnel are predicted, improving the accuracy of the prediction results.

[0084] 3. According to the ignition scenarios, the catastrophic accident consequences such as jet fire, flash fire, deflagration, and explosion are included. The risk assessment consequences are classified and detailed, and corresponding countermeasures can be taken according to different disaster consequences, reasonably allocating rescue resources.

[0085] 4. The safety of social personnel in various disaster accidents is analyzed, taking the safety of personnel's lives as a new index for evaluating the accident consequences.

[0086] 5. An air ventilation array is formed by the intersection of longitudinal ventilation and transverse exhaust, which combines the control and exhaust technologies. This can not only effectively dilute the accumulated hydrogen cloud, but also control the hydrogen within a certain range. Description of the Drawings

[0087] Figure 1 This is the flow chart of the method.

[0088] Figure 2 This is the schematic structural diagram of the on-vehicle high-pressure hydrogen storage system described in the present invention.

[0089] Figure 3 This is the fault tree of the hydrogen storage system leakage described in the present invention.

[0090] Figure 4 This is the leakage model described in the present invention.

[0091] Figure 5 This is the fault tree of the explosion of the on-vehicle hydrogen storage system in the tunnel described in the present invention.

[0092] Figure 6 This is the flow chart of the combined ventilation automatic regulation scheme described in the present invention.

[0093] In the figure: 1. Hydrogen storage cylinder of the main shut-off valve, 2. Outlet filter, 3. Pressure sensor, 4. Temperature sensor, 5. Check valve, 6. Temperature-driven pressure relief device, 7. Manual stop valve, 8. Drain needle valve, 9. Pressure reducing valve, 10. Safety valve, 11. Solenoid valve. Detailed Implementation Manner

[0094] The technical method for predicting the leakage and explosion risk of hydrogen energy vehicles in tunnels and automatic ventilation emergency disposal specifically includes the following steps:

[0095] First, analyze the on-vehicle high-pressure hydrogen storage system and classify and mark the potential leakage points. The on-vehicle high-pressure hydrogen storage system includes a hydrogen refueling module, a hydrogen filling module, and a hydrogen supply module. In this scenario, it is set as a large hydrogen fuel cell vehicle in operation, so the hydrogen refueling module in the hydrogen storage system is not considered. For common large hydrogen fuel cell vehicles, they are often equipped with eight hydrogen storage units. Every four hydrogen storage units form a unit group. Each hydrogen storage unit mainly has five components, which are also the main leakage points of the on-vehicle high-pressure hydrogen storage system: valves, instruments, nodes, pipelines, and storage tanks. In the real scenario, the on-vehicle high-pressure hydrogen storage system mainly uses type III cylinders and type IV cylinders, which have good compressive resistance and impact resistance. In addition, the valves in the hydrogen storage system mainly include: main shut-off valve, check valve 5, manual stop valve 7, solenoid valve 11, drain needle valve 8, and safety valve 10. The thermal pressure relief device (TPRD), as a hydrogen-related device, is used to release hydrogen in a timely manner when the internal pressure of the storage tank increases to a certain threshold (caused by high temperature) to ensure that the storage tank will not undergo catastrophic collapse. Considering that the working mode of the TPRD is similar to that of the valve, it is classified into the valve category. The instruments on the hydrogen storage line mainly include temperature sensors and pressure sensors. The valves and instruments are connected in series with the storage tank through conduits to form a hydrogen storage unit. The hydrogen storage units are connected in parallel to the hydrogen fuel cell system using hoses.

[0096] Next, it is necessary to analyze the potential leakage points and leakage forms of the on-vehicle high-pressure hydrogen storage system. The main leakage points of the on-vehicle high-pressure hydrogen storage system are: valves, instruments, nodes, pipelines, and storage tanks. In the actual scenario, the high-pressure hydrogen storage tank has high strength. However, it is still possible to undergo catastrophic collapse during a strong impact. In addition, hydrogen embrittlement may also cause leakage of the storage tank. The reasons for valve leakage in the on-vehicle hydrogen storage system include component loosening, strong impact, component failure, etc. It should be noted that for the temperature-driven pressure relief device (TPRD), the high temperature impact brought by fire accidents and the like will also cause hydrogen leakage accidents. The temperature sensor and pressure sensor are directly connected to the hydrogen pipeline. Strong impact may cause loosening, failure, and damage of the sealing part of the instrument. In addition, there are a large number of connection nodes in the pipeline of the hydrogen storage system. If not repaired for a long time or subjected to a major impact, cracks are very likely to occur. The hydrogen storage system has multiple hydrogen storage units, and conduits are required for unit connection. As a type of pipeline, the strength of the conduit is relatively low. Once subjected to a strong impact, rupture and breakage accidents are very likely to occur.

[0097] The annual frequency of hydrogen leakage includes different leakage conditions of different sizes. The leakage sizes include 0.01% (small hole leakage / slight leakage), 0.1%, 1%, 10%, and 100% (rupture / collapse). The leakage frequency of a single component is calculated according to the fatigue usage degree of the component.

[0098] In HyRAM, the leakage size is represented by k. The formula for calculating the annual leakage frequency of hydrogen with a leakage size of 100% is as follows:

[0099]

[0100] The formula for calculating the annual leakage frequency of hydrogen with other sizes is as follows:

[0101]

[0102]

[0103] is a potential leakage point in the on-vehicle high-pressure hydrogen storage system. is the average leakage rate when the leakage size of component i is k. It is defaulted to: .

[0104] There are two types of leakage forms caused by the above-mentioned leakage points: instantaneous leakage and continuous leakage. Instantaneous leakage occurs when the storage tank collapses and isolation measures are implemented in a timely manner after a leakage accident. If the leakage point is not isolated or the valve is not shut down during the accident, a continuous leakage accident will be triggered.

[0105] Then, the hydrogen mass rate curves under different leakage forms are calculated. Since the time of instantaneous leakage is short, the influence of the initial pressure of the storage tank on the leakage amount is not considered. Therefore, based on the instantaneous leakage accident, the mass of hydrogen exposed to the air can be obtained by directly comparing the mass of the storage tank before and after. For continuous leakage accidents, the mass flow rate of the leaked hydrogen presents a continuous curve. Considering that the small-hole leakage of high-pressure hydrogen is essentially a conversion between pressure potential energy and kinetic energy. Therefore, it is necessary to determine the calculation result according to the magnitude of the initial leakage pressure. The equations commonly used to calculate the mass rate of the leaked hydrogen are the ideal gas state equation and the Abel-Noble state equation developed by Molkov. The ideal gas state equation is applicable to hydrogen leakage below 10 MPa. When the leakage pressure is greater than 10 MPa, the Abel-Noble state equation has higher accuracy. The hydrogen storage pressure of large hydrogen fuel cell vehicles is 35 MPa. Therefore, during the process from hydrogen leakage to leakage end, two hydrogen leakage models are involved.

[0106] The ideal gas state equation can judge the flow state of hydrogen according to the relationship between the initial pressure of the leaked hydrogen and the ambient pressure. When the relationship between the initial pressure of hydrogen leakage and the ambient pressure satisfies the following formula, the hydrogen leakage belongs to the supersonic flow state. This indicates that the outlet pressure of the leakage port is the critical pressure and the leakage velocity is the local sound velocity of hydrogen.

[0107]

[0108] At this time, the mass formula of the leaked hydrogen is:

[0109]

[0110] When the relationship between the initial pressure of hydrogen leakage and the ambient pressure satisfies the following formula, the hydrogen leakage is in a subsonic flow state. This indicates that the outlet pressure of the leakage port is the ambient pressure and the leakage velocity is lower than the local speed of sound.

[0111]

[0112] At this time, the mass formula of the leaked hydrogen is:

[0113]

[0114] p0 is the ambient pressure; p is the initial pressure; κ is the adiabatic index of the gas; Q is the hydrogen leakage rate, kg / s; C d is the gas leakage coefficient; A is the area of the leakage port; M is the molar mass of the gas; R is the gas constant; T is the temperature.

[0115] Calculation process of the Abel-Noble equation of state:

[0116]

[0117] From the mass conservation equation and the energy conservation equation, we can obtain:

[0118]

[0119]

[0120] The density of hydrogen at the actual leakage outlet:

[0121]

[0122] The leakage velocity formula of hydrogen at the actual leakage outlet:

[0123]

[0124] The hydrogen leakage rate formula:

[0125]

[0126] Then, identify the possible ignition risks. Based on the leakage forms of on-vehicle high-pressure hydrogen storage systems, different disaster consequences may occur in case of ignition sources. For instantaneous leakage forms, if the leaked hydrogen immediately encounters an ignition source, flashover or explosion (catastrophic instantaneous leakage caused by tank collapse) may occur according to the scale of instantaneous leakage; if ignition is delayed, as the ignition delay time increases, the cloud risk gradually changes from explosion and flashover to a risk-free state of cloud dissipation. For continuous leakage forms, immediate ignition will result in jet fire (ignited at the leakage port), flashover (accumulated gas catches fire), and explosion; delayed ignition will lead to accidents such as explosion, detonation, and flashover. It is necessary to preliminarily define the harm degree of accident consequences. Flashover and dissipated clouds cause almost no harm to the surrounding environment and personnel. The consequences of jet fire pose a temperature risk at a certain distance, but the possible domino disasters caused by jet fire still need to be considered. The consequences of explosion accidents are the main form of risk to personnel in hydrogen leakage accidents. The high-temperature field formed by the explosion has a wide range, and the explosion overpressure can penetrate a whole tunnel.

[0127] The ignition probability model adopts the subjective Bayesian algorithm probability. For the subjective Bayesian algorithm probability, basic data are usually obtained through the expert judgment method: select cross-field experts in hydrogen energy safety, pressure vessels, risk engineering, etc. to form an evaluation group, decompose the target event into risk factors with clear physical meanings and make a standardized evaluation scale, and collect the qualitative judgments of experts based on engineering experience and accident cases through back-to-back communication methods. After iterative feedback, a convergent fuzzy probability interval is formed. On this basis, the analytic hierarchy process (AHP) is introduced to establish an expert weight dynamic calibration model, structurally characterize the ability characteristics of no less than 5 experts, quantify the relative importance of each dimension through pairwise comparison matrices, and calculate the individual weight coefficients in combination with the eigenvector method.

[0128] Then, construct a comprehensive disaster occurrence probability model. Establish a two-dimensional evaluation system for immediate ignition and delayed ignition, and systematically analyze the transformation mechanism of disaster forms under different triggering conditions: focus on evaluating the effectiveness of isolation area settings in the unburned diffusion stage, and distinguish different disaster modes such as jet fire, deflagration, and chemical explosion in the combustion stage, especially for the expansion physical explosion scenario caused by the rupture of high-pressure storage tanks. Based on the event tree analysis method, integrate the probability distribution of leakage rate, the spatio-temporal distribution characteristics of ignition sources, and the coupling coefficient of multiple disasters, demonstrate the triggering conditions and probability weights of catastrophic rupture in the scenario of tank impact damage, and finally calculate the comprehensive risk probability of the disaster chain.

[0129] Accident probability calculation method:

[0130]

[0131]

[0132]

[0133]

[0134] where annual frequency of event x, probability of occurrence of event x.

[0135] Then, based on the disaster consequences, combined with the overpressure hazard model and the temperature hazard model, the risks of personnel at different locations are evaluated, and the risk areas are divided. Among them, the disaster consequences are measured by using the individual risk probability (the probability of death within a specific location unit), referring to the probit probability function recommended in the Purple Book and by Sandia. A risk contour map is drawn to represent the risk levels (such as low risk, medium risk, high risk) in different areas.

[0136] HyRAM uses a probability unit model to determine the probability of injury or death under a specific exposure scenario. The probability unit model is a linear combination of predictors, and the inverse cumulative distribution function of the model is associated with the normal distribution. Probability of death:

[0137]

[0138] There are many probability unit models that can predict the injuries and losses caused by thermal radiation and overpressure. The degree of hazard of thermal radiation is usually expressed in thermal dose units, which can be expressed as a function of the heat flux intensity and the exposure time. Calculation of thermal dose units:

[0139]

[0140] I is the radiant heat flux intensity, and t is the exposure duration.

[0141] The overpressure hazard model adopts the overpressure-impulse criterion. The Netherlands Organization for Applied Scientific Research (TNO) proposes that overpressure hazards can be divided into human lung injury, head injury, and body injury, and the corresponding probability of death for each part is calculated as follows:

[0142]

[0143]

[0144]

[0145] In the formula, m is the mass of the injured person in the explosion scenario, P is the pressure, and I is the impulse.

[0146] Summarize the risk data of the accident scenarios, combine information such as leakage probability, ignition probability, and accident consequences, converge the data set, and combine to obtain the combustion and explosion risk prediction model of the high-pressure hydrogen storage system in the tunnel.

[0147] Based on the consequences of multi-accident scenarios of hydrogen leakage accidents, in this study, a longitudinal ventilation array penetrating the tunnel was constructed by numerically simulating the jet fan mechanism, and a lateral exhaust vent array with equal spacing was symmetrically arranged centered on the leakage source directly above the leaking vehicle. Among them, the lateral exhaust vents maintain a constant spacing, and the exhaust air volume is used as the main control variable. An array of hydrogen concentration sensors is arranged at equal intervals along the longitudinal direction of the tunnel ceiling to obtain the accumulated hydrogen concentration information. In addition, hydrogen concentration sensors are also arranged at equal intervals along the axis of the vertical exhaust vents within a radius of 20 m from the leakage point to monitor the hydrogen concentration in the exhaust duct. Using 4% hydrogen concentration as the hydrogen perception of the leakage accident, it is considered to use the longitudinal ventilation array to reduce the hydrogen concentration on the ceiling, and supplemented by lateral ventilation to control the accumulated hydrogen on the ceiling within a range of 20 m from the leakage point radius. In order to achieve the above combined functions, an automated hydrogen concentration feedback system is proposed:

[0148] The data of the hydrogen concentration sensors are transmitted to the computer through cables. For each sensor arranged longitudinally on the tunnel ceiling, according to its installed coordinates, the corresponding row and column indexes are matched, and the transmitted data are stored in the corresponding rows and columns of the data matrix; in order to reduce cost consumption, it is set that when the hydrogen concentration is equal to 0, the system will default to the standby state, and when the hydrogen concentration is greater than 0, the value fed back by the sensor to the computer is 1, thus activating the system. After a hydrogen leakage accident occurs, the computer will refresh the data matrix in real time and check the hydrogen concentration in sequence according to the ventilation direction. Among them, the hydrogen concentration at the sensor located in the i-th row and j-th column is: h i,j . If in the detected row, the maximum hydrogen concentration is greater than or equal to 4%, and the concentration in the next row is less than 4% at the same time, then the position of this row is located as the front of the hydrogen combustible cloud.

[0149] For the vertical hydrogen concentration sensor system arranged in the axis of the exhaust duct, after the longitudinal ventilation system is activated, it will receive information feedback and then be activated. A data column is constructed according to its longitudinal coordinates, and the hydrogen concentration is detected in sequence from bottom to top according to the height. Among them, the hydrogen concentration in the k-th row is: h k . If the hydrogen concentration in the detected row is greater than or equal to 8%, and the hydrogen concentration in the next row is less than 8%, then the position of this row is defined as the height of the explosion risk.

[0150] The front of the hydrogen combustible cloud is subject to the lateral exhaust air volume, and the height of the explosion risk is subject to the longitudinal ventilation speed. Controlling the hydrogen cloud within a range with a radius of 20 m centered on the leakage point is the purpose of this system. Considering that under different exhaust air volumes, the qualified longitudinal ventilation speeds are not the same. Therefore, the height of the explosion risk is also used as a risk prediction index for leakage accidents. A ventilation plan matrix composed of different lateral exhaust air volumes and longitudinal ventilation speeds is constructed. Considering practical applications, the lateral exhaust air volume is controlled within 30 - 150 m 3 / s, the longitudinal ventilation speed is controlled at 1 - 5 m / s. In addition, cost factors also need to be considered. Finally, by comparing the risk parameters under different ventilation matrix combinations that meet the qualified requirements, the ventilation emergency plan with the optimal comprehensive economic and safety performance is selected.

Claims

1. A method for predicting the leakage and combustion explosion risk of tunnel hydrogen energy vehicles and automatic ventilation emergency disposal, characterized in that, It includes the following steps: S1. Analyze the on-vehicle high-pressure hydrogen storage system, classify and mark the potential leakage points; based on the classified potential leakage points, identify various failure modes of hydrogen fuel cell vehicles in the tunnel, and analyze the possible failure types of each component; define different accident scenarios through the fault tree, and clarify the relevant failure types and their consequences for each accident scenario; S2. Determine the leakage frequency and complete rupture frequency according to the leakage scenarios of different hydrogen-related components; when calculating the leakage frequency, correspond the leakage aperture according to the hydrogen storage pressure and hydrogen storage volume to obtain the leakage frequency; S3. Analyze the potential leakage points and leakage forms of the on-vehicle high-pressure hydrogen storage system under different accident scenarios; The leakage forms caused by the leakage points are divided into: instantaneous leakage and continuous leakage; calculate the hydrogen mass rate curves under different leakage forms: For the instantaneous leakage accident, the difference in the mass of the storage tank before and after is used to obtain the mass of the leaked hydrogen; For the continuous leakage accident, when the leakage pressure of hydrogen is below 10 MPa, the ideal gas state equation is used to calculate the hydrogen mass rate curve; when the leakage pressure is greater than 10 MPa, the Abel-Noble state equation is used to calculate the hydrogen mass rate curve; S4. Build a comprehensive disaster occurrence probability model; establish an instant ignition and delayed ignition two-dimensional evaluation system through the HyRAM model and the HYEX model, and the disaster forms are: unignited, jet fire, flash fire and explosion; based on the fault tree analysis method, integrate the leakage rate probability distribution, the spatio-temporal distribution characteristics of the ignition source and the multi-disaster coupling coefficient, and finally calculate the comprehensive risk probability of the disaster chain; S5. Based on the disaster consequences, combined with the overpressure hazard model and the temperature hazard model, evaluate the accident risk according to the fatality rate and the influence range of personnel; summarize the risk data of the accident scenario, and combine the leakage probability, the ignition probability and the accident consequences to obtain the explosion risk prediction model of the tunnel high-pressure hydrogen storage system; S6. Based on the multi-accident scenario consequences of the hydrogen leakage accident, set up jet fans through numerical simulation to construct a longitudinal ventilation array running through the tunnel, and symmetrically arrange a transverse exhaust port array at equal intervals centered on the leakage source directly above the leaking vehicle; among them, the transverse exhaust port maintains a constant spacing, and the exhaust air volume is used as a control variable; the longitudinal ventilation array and the transverse ventilation array are cross-combined to form a ventilation array matrix; through the hydrogen leakage risk assessment system composed of hydrogen concentration sensors and computers, compare the risks of the tunnel on-vehicle high-pressure hydrogen storage system under emergency disposal technologies, and obtain the optimal economic, safe and efficient combined ventilation emergency disposal plan with the specified risk weight as the evaluation index.

2. The method for predicting the leakage and explosion risk of hydrogen energy vehicles in tunnels and automatically ventilating and emergency disposal according to claim 1, wherein, In the step S1, the leakage points of the on-vehicle high-pressure hydrogen storage system include valves, instruments, nodes, pipelines, and storage tanks.

3. A method for predicting the leakage and explosion risk of hydrogen energy vehicles in tunnels and automatically ventilating and emergency disposal, according to claim 1, characterized in that In step S2, the annual frequency of hydrogen leakage includes leakage conditions of different sizes, and the leakage sizes include 0.01%, 0.1%, 1%, 10%, 100%; the leakage frequency of a single component is calculated according to the fatigue usage degree of the component; In HyRAM, the leakage size is represented by k and the calculation formula for the annual hydrogen leakage frequency with a leakage size of 100% is as follows: ； When the leakage size is not 100%, the formula for calculating the annual frequency of hydrogen leakage is: ； ； is a potential leakage point in the in-vehicle high-pressure hydrogen storage system, is the component i The leakage size is k The average leakage rate at this time, is .

4. A method for predicting the leakage and explosion risk of hydrogen energy vehicles in tunnels and automatically ventilating and emergency disposal, according to claim 1, characterized in that In step S3, the hydrogen mass rate curve under continuous leakage form is calculated as follows: The ideal gas state equation determines the flow state of hydrogen according to the relationship between the initial pressure of the leaked hydrogen and the ambient pressure; When the relationship between the initial pressure of hydrogen leakage and the ambient pressure satisfies the following formula, the hydrogen leakage belongs to the supersonic flow state; the outlet pressure of the leakage port is the critical pressure, and the leakage velocity is the local sound velocity of hydrogen; ； At this time, the mass formula of the leaked hydrogen: ； When the relationship between the initial pressure of hydrogen leakage and the ambient pressure satisfies the following formula, the hydrogen leakage belongs to the subsonic flow state; the outlet pressure of the leakage port is the ambient pressure, and the leakage velocity is lower than the local sound velocity; ； At this time, the mass formula of the leaked hydrogen: ； In the formula, p 0 is the ambient pressure; p is the initial pressure; κ is the adiabatic index of the gas; Q is the hydrogen leakage rate, kg / s; C d is the gas leakage coefficient; A is the leakage port area; M is the molar mass of the gas; R is the gas constant; T is the temperature; Calculation process of the Abel-Noble state equation: ； From the mass conservation equation and the energy conservation equation: ； ； Density of hydrogen at the real leakage outlet: ； Leakage velocity formula of hydrogen at the real leakage outlet: ； Leakage amount formula of hydrogen: ； In the formula, ρ 1 is the initial hydrogen density, kg / m 3 ; p 1 is the initial pressure, Pa; b is the Abel-Noble residual volume coefficient; R H2 is the hydrogen gas constant, taken as 4.124×103 J / (kg·K); T1 is the initial temperature, K; κ is the adiabatic index; ρ 3 is the hydrogen density at the real leakage orifice, kg / m 3 ; T 3 is the temperature at the real leakage orifice, K; p 3 is the pressure at the real leakage orifice, Pa; u 3 is the leakage velocity at the real leakage orifice, m / s; Q is the mass leakage flow rate, kg / s; A is the leakage orifice area, m 2 .

5. A method for predicting the leakage and combustion explosion risk of a tunnel hydrogen energy vehicle and automatically ventilating and emergency disposing, according to claim 1, characterized in that In step S4, the probability calculation method: ； ； ； ； Among them, is the annual frequency of the event x , is the occurrence probability of the event x .

6. The method for predicting the leakage and explosion risk of a tunnel hydrogen energy vehicle and automatically ventilating and emergency disposal according to claim 1, wherein In step S5, the disaster consequence is measured by using the individual risk probability, that is, the fatality probability per unit of a specific location: ； wherein is the probability of death, Y is the probit model, is the normal cumulative distribution function; The temperature hazard model adopts the hazard degree of thermal radiation, that is, the thermal dose unit, which is expressed as a function of the heat flux intensity and the exposure time; calculation of the thermal dose unit: ； In the formula, I is the radiative heat flux intensity, t is the exposure duration; The overpressure hazard model adopts the overpressure-impulse criterion. The overpressure hazard is divided into human lung injury, head injury, and body injury, and the corresponding fatality probability calculation for each part: ； ； ； In the formula, m is the mass of the injured person in the explosion scenario, P is the pressure, I is the impulse.

7. A method for predicting the leakage and combustion explosion risk of a tunnel hydrogen energy vehicle and automatically ventilating and emergency disposal according to claim 1, characterized in that In step S6, the hydrogen leakage risk assessment system is: An array of hydrogen concentration sensors with equal spacing is arranged longitudinally along the tunnel ceiling to obtain the accumulated hydrogen concentration information; hydrogen concentration sensors with equal spacing are also arranged at the axis position of the vertical exhaust vents within a radius of 20 m from the leakage point to monitor the hydrogen concentration in the exhaust duct; 4% hydrogen concentration is used as the hydrogen perception of the leakage accident, and the longitudinal ventilation array is used to reduce the hydrogen concentration on the ceiling, and supplemented by transverse ventilation to control the accumulated hydrogen on the ceiling within a radius of 20 m from the leakage point; The data of the hydrogen concentration sensors are transmitted to the computer. For each sensor arranged longitudinally on the tunnel ceiling, its corresponding row and column indexes are matched according to the coordinates where it is installed, and the transmitted data are stored in the corresponding rows and columns in the data matrix; it is set that when the hydrogen concentration is equal to 0, the system will default to the standby state, and when the hydrogen concentration is greater than 0, the value fed back by the sensor to the computer is 1 to activate the system.

8. A method for predicting the leakage and explosion risk of a tunnel hydrogen energy vehicle and automatically ventilating and emergency handling, according to claim 7, characterized in that The front of the hydrogen combustible cloud is subject to the lateral exhaust air volume, and the risk of combustion explosion is highly subject to the longitudinal ventilation wind speed; a ventilation plan matrix composed of different lateral exhaust air volumes and longitudinal ventilation wind speeds is constructed, with the lateral exhaust air volume controlled at 30~150 m 3 / s and the longitudinal ventilation wind speed controlled at 1~5 m / s.

9. A method for predicting the leakage and combustion explosion risk of tunnel hydrogen energy vehicles and automatically ventilating and emergency disposal according to claim 7, characterized in that: After a hydrogen leakage accident occurs, the computer will refresh the data matrix in real time and check the hydrogen concentration in sequence according to the ventilation direction. Among them, the hydrogen concentration at the sensor in row i row j column is: h i,j ; If in the detected row, the maximum hydrogen concentration is greater than or equal to 4%, and at the same time the concentration in the next row is less than 4%, then the position of this row will be located as the front of the hydrogen combustible cloud.

10. A method for predicting the leakage and explosion risk of hydrogen energy vehicles in tunnels and automatically ventilating and emergency disposal according to claim 7, characterized in that: For a hydrogen concentration sensor system vertically arranged in the axis of the exhaust duct, information feedback will be received after the longitudinal ventilation system is activated; a data column is constructed according to its longitudinal coordinates, and the hydrogen concentration is detected sequentially from bottom to top according to the height, where the hydrogen concentration at k row is: h k ; if the hydrogen concentration in the detected row is greater than or equal to 8%, and the hydrogen concentration in the next row is less than 8%, then the position of this row is defined as the explosion risk height.

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