Method for evaluating radiation hazard of high-pressure hydrogen cylinder discharge flame and combustion device

Abstract

The application discloses a high-pressure hydrogen storage cylinder discharge flame radiation risk assessment method and a combustion device. t m In the jet fire radiation flux distribution of the cylinder discharge stage; S4, total radiation flux at the target test point in the cylinder discharge stage is obtained; according to the radiation flux at the target test point in the fire burning stage and the total radiation flux at the target test point after the cylinder discharge, the danger area of the target test point is judged. The application predicts the flame field radiation in the high-pressure hydrogen storage cylinder fire burning process, judges the dangerous distance based on the personnel radiation damage threshold, and provides a theoretical basis for personnel risk early warning in the high-pressure hydrogen storage cylinder fire burning scene.

Description

Technical Field

[0001] This invention relates to the field of radiation hazard assessment of high-pressure hydrogen storage cylinder venting flames, and in particular to a method and combustion device for assessing radiation hazard of high-pressure hydrogen storage cylinder venting flames. Background Technology

[0002] To address climate change caused by excessive consumption of primary energy sources, countries worldwide are actively pursuing energy transitions to solve environmental pollution and the greenhouse effect. Hydrogen energy, with its high calorific value, pollution-free operation, and high conversion rate, represents a highly promising direction for future energy development. Under the strategic backdrop of the "dual-carbon" policy, my country is also vigorously promoting the development of the hydrogen energy industry, particularly in the transportation sector. New energy vehicles using hydrogen fuel cells to replace traditional internal combustion engines are gradually gaining popularity in the consumer market. Hydrogen fuel cell vehicles primarily use high-pressure hydrogen storage tanks to store gaseous hydrogen, which is then transported to the fuel cell to react with air and generate electricity to power the vehicle. The only product of this reaction is water, which does not cause environmental pollution or additional carbon emissions. With national policy support, hydrogen fuel cell vehicle technologies and industries will continue to develop rapidly, bringing greater benefits to my country's economic development and environmental protection.

[0003] Because fuel cell vehicles are prone to fires due to collisions and electrical circuit problems, the fire safety of their hydrogen storage systems is a key concern in the industry. Although the first phase of the global technical regulations for fuel cell electric vehicles stipulates that onboard high-pressure hydrogen storage cylinders should undergo fire tests to verify their emergency release process in a fire, deficiencies in the regulations regarding the fire system have resulted in ineffective control and consistency in aspects such as flame stability, fire zone transitions, and fire source power. Currently, no solution has been found that can quickly identify the risk of heat radiation damage from flames during a high-pressure hydrogen storage cylinder fire and assess the dangerous distance for personnel. Summary of the Invention

[0004] The purpose of this invention is to provide a method and combustion device for assessing the radiation hazard of high-pressure hydrogen storage cylinder venting flames, which can quickly predict the fire stage and the external radiation distribution of the flames during the venting of high-pressure hydrogen storage cylinders, and evaluate the safe distance of the flames from personnel.

[0005] The technical solution adopted by this invention to solve the problems of the prior art is a method for assessing the radiation hazard of a high-pressure hydrogen storage cylinder venting flame, comprising the following steps:

[0006] S1. Conduct a fire test on the high-pressure hydrogen storage cylinder: The high-pressure hydrogen storage cylinder is ignited using a combustion device; this includes the following steps:

[0007] S101. Calculate the radiation flux at the target test point during the localized combustion stage: Perform localized combustion on the high-pressure hydrogen storage cylinder, set up a sampling point outside the fire source, and install a radiation heat flux meter at the sampling point to record the flame radiation flux; calculate the fire source power during the localized combustion stage based on the flame radiation flux and the area of ​​the fire source region generated by the combustion device; set up multiple target test points horizontally outside the fire source from near to far. M represents the number of target test points; the target test points are obtained through the power of the fire source. Local fire radiation flux Record each of the target test points. Localized fire radiation flux The radiation flux distribution during the local fire phase was obtained.

[0008] S102. Calculate the radiation flux at the target test points during the overall combustion phase: The high-pressure hydrogen storage cylinder is subjected to overall combustion, ensuring the flame source generated by the combustion device completely envelops the cylinder. A sampling point is set outside the flame source, and a radiation heat flux meter is installed at each sampling point to record the flame radiation flux. The flame source power during the overall combustion phase is calculated based on the flame radiation flux and the area of ​​the flame source region generated by the combustion device. The radiation flux at each target test point is then used to obtain the radiation flux at the target test points. Overall fire radiation flux Record each of the target test points. Overall fire radiation flux Thus, the radiation flux distribution during the overall fire phase was obtained;

[0009] S2. Obtain the jet fire heat release rate and jet fire length during the cylinder venting stage: The high-pressure hydrogen storage cylinder is ignited until the safety pressure relief device is activated, causing the hydrogen storage cylinder to vent and emit a jet fire; the heat release rate of the jet fire is obtained through the venting critical pressure of the hydrogen storage cylinder. With the length of the jet fire :

[0010] The heat release rate for:

[0011]

[0012] in, The hydrogen flow rate at the vent nozzle is obtained from the following formula:

[0013]

[0014] Let ΔH be the diameter of the vent of the hydrogen storage cylinder, and ΔH be the heat of hydrogen combustion. p0 is a constant, and p0 is the maximum pressure value of the gas cylinder before it is released. R is the adiabatic coefficient; T is the hydrogen gas constant; b is the hydrogen temperature at the vent nozzle; K is the control volume constant; and K is the loss coefficient for hydrogen venting. p ΔT represents the specific heat capacity at constant pressure of hydrogen; ΔT represents the temperature drop during the hydrogen flow process.

[0015] Jet fire length for:

[0016]

[0017] in, To release the hydrogen density at the nozzle; The density of the outside air; This is the ratio for the complete combustion reaction of hydrogen.

[0018] S3, based on the heat release rate of the jet fire With the length of the jet fire The target test points were obtained. The distribution of jet fire radiation flux during the gas cylinder release phase includes the following steps:

[0019] S301, in the length of the jet fire N flame point sources are selected sequentially along the central axis of the jet flame within the range. , i=1,2,……,N, and make each of the flame point sources uniformly distributed;

[0020] S302, Based on the heat release rate of the jet fire Identify each flame source At the target test point Incident radiant flux of the jet flame at the location :

[0021]

[0022] Among them, D i flame point source With the target test point The distance between them; Indicates flame source and target test points The angle between the line connecting the two sides and the horizontal plane; Atmospheric transmittance; For jet fire radiation fraction; w i flame point source Weighted strength N represents the total number of flame sources; n represents the number of heat sources within the first 0.75N.

[0023] S4. Obtain the total radiative flux at the target test points during the gas cylinder release phase: [The text abruptly ends here, likely due to an incomplete sentence or a missing section.] Radiation flux during the overall fire phase and incident radiation flux of jet flame By summing the corresponding values, we can obtain the target test points. Total radiant flux after gas cylinder venting ;

[0024] S5. Based on the radiation flux at the target test point during the fire stage and the total radiation flux at the target test point after the gas cylinder is released, determine the danger zone of the target test point:

[0025] when At that time, the target test point It is in a danger zone during the localized fire stage;

[0026] when At that time, the target test point The area is in a safe zone during the localized fire stage;

[0027] when At that time, the target test point It is in a danger zone during the overall fire stage;

[0028] when At that time, the target test point The area was in a safe zone during the overall fire phase;

[0029] when At that time, the target test point The area is in danger during the gas cylinder release phase;

[0030] when At that time, the target test point The gas cylinder is in a safe zone during the venting phase.

[0031] In step S101, the fire source generated by the combustion device during localized fire envelops the tail end of the high-pressure hydrogen storage cylinder.

[0032] The fire source power in step S1 during the localized fire stage and the overall fire stage is:

[0033]

[0034]

[0035] in, This refers to the fire source power during the localized fire stage. This represents the flame radiation flux obtained from the thermal radiation flowmeter at the sampling point during the localized fire stage. This refers to the fire source power during the overall burning phase. The flame radiation flux obtained by the thermal radiation flowmeter at the collection point during the overall combustion stage; Atmospheric transmittance; The fire source radiation fraction; For fire source perspective factors; This refers to the area of ​​the fire source region generated by the combustion device during the localized fire stage. The area of ​​the fire source region generated by the combustion device during the overall combustion stage;

[0036] The target test point Localized fire radiation flux and overall fire radiation flux Method:

[0037]

[0038]

[0039] Fire source perspective factor The method for determining this includes the following steps:

[0040] A. Determining the flame combustion surface: The plane containing the fire source area of ​​the combustion device is taken along the axial direction of the hydrogen storage cylinder as the length direction of the fire source, and along the radial direction of the hydrogen storage cylinder as the width direction of the fire source; the direction perpendicular to the plane containing the fire source area is taken as the height direction of the fire source; a cuboid model is established using the fire source length, fire source width, and flame height formed by the fire source area of ​​the combustion device as its length, width, and height; wherein, the plane containing the width and height of the cuboid model is taken as the combustion surface:

[0041] B. Coordinate System Establishment: A coordinate system is established according to the different positions of the target points in the external field to be measured. The target points in the external field to be measured include the acquisition points and the target test points.

[0042] When the target point in the external field to be measured is set in the radial direction of the hydrogen storage cylinder, a three-dimensional rectangular coordinate system is established with the width direction of the fire source as the X-axis, the length direction of the fire source as the Y-axis, the height direction of the fire source as the Z-axis, and the center of the combustion surface as the origin.

[0043] When the target point in the field to be measured is located in the axial direction of the hydrogen storage cylinder, a three-dimensional rectangular coordinate system is established with the length direction of the fire source as the X-axis, the width direction of the fire source as the Y-axis, the height direction of the fire source as the Z-axis, and the center of the combustion surface as the origin.

[0044] C. Determine the fire source perspective factor F:

[0045]

[0046] Where x is the vertical distance between the target point in the test field and the combustion surface; y1 and y2 are the intercepts of the combustion surface on the Y-axis, and z1 and z2 are the intercepts of the combustion surface on the Z-axis.

[0047] .

[0048] A combustion device for assessing the radiation hazard of a venting flame from a high-pressure hydrogen storage cylinder includes a rectangular support with two sets of combustion components fixed on it, arranged symmetrically. Each combustion component includes parallel gas pipelines and a mass flow controller connected to the gas pipelines. The gas pipelines are pipes open at one end and closed at the other, and are equipped with several gas nozzles connected to them. The open end of each gas pipeline is connected to a fuel supply end via a buffer tank through the mass flow controller. Points are installed between the gas pipelines. The ignition electrode is electrically connected to the ignition transformer. A hydrogen storage cylinder fixing beam is provided above the rectangular support. The hydrogen storage cylinder fixing beam is set perpendicular to the layout direction of the gas pipeline. The hydrogen storage cylinder fixing beam is provided with a fixing slot. The hydrogen storage cylinder is fixedly set in the fixing slot, so that the high-pressure hydrogen storage cylinder is set parallel to the gas pipeline and the head and tail of the high-pressure hydrogen storage cylinder are respectively located above the two sets of combustion components. Thermal radiation flow meters are respectively installed on the long side and the short side of the rectangular support. The thermal radiation flow meters are connected to the data acquisition unit through the cooling water tank.

[0049] The gas pipeline is arranged parallel to the long side of the rectangular support, and the closed end of the gas pipeline is located in the middle of the rectangular support. The hydrogen storage cylinder fixing beam is fixed in the middle of the rectangular support.

[0050] The beneficial effects of this invention are as follows: By subjecting high-pressure hydrogen storage cylinders to partial and overall fire, the invention determines the external thermal radiation during the fire stage based on the area and heat source power of the partial and overall fire. After the hydrogen storage cylinder is vented, the length of the resulting jet fire is estimated based on the peak pressure inside the cylinder, and its external thermal radiation is estimated based on the heat release rate of the jet fire. Based on the external radiation of the flame and the human body's thermal radiation injury threshold, this invention achieves the goal of rapidly predicting the safe distance for personnel affected by the flame radiation emitted during the venting of a high-pressure hydrogen storage cylinder in a fire. Therefore, this invention predicts the external radiation of the flame during the fire process of a high-pressure hydrogen storage cylinder and determines the danger distance based on the human body's radiation injury threshold, providing a theoretical basis for personnel risk warning in high-pressure hydrogen storage cylinder fire scenarios. Attached Figure Description

[0051] Figure 1 This is a basic flowchart of the evaluation method of the present invention.

[0052] Figure 2 This is a schematic diagram of the combustion device in this invention.

[0053] Figure 3 This is a schematic diagram illustrating the determination of the combustion surface and the establishment of the coordinate system during the determination of the fire source perspective factor F in this invention.

[0054] Figure 4 This is a schematic diagram for calculating the incident radiation flux of a jet fire at any target test point.

[0055] Figure 5 This is a schematic diagram showing the distance of flame radiation risk during the burning process of a 140 L-35 MPa hydrogen storage cylinder.

[0056] In the diagram: 1-Fuel supply end, 2-Buffer tank, 3-Mass flow controller, 4-Ignition electrode, 5-Ignition transformer, 6-Thermal radiation flow meter, 7-Data acquisition unit, 8-Gas pipeline, 8a-Gas nozzle, 9-Hydrogen storage cylinder fixing beam, 9a-Fixing slot, 10-Rectangular bracket. Detailed Implementation

[0057] The present invention will be described below with reference to the accompanying drawings and specific embodiments:

[0058] The design concept of this invention is as follows:

[0059] The combustion device is activated to generate a localized or complete ignition source capable of enveloping the high-pressure hydrogen storage cylinder, causing it to burn locally or entirely. Data recorded by a radiative heat flux meter placed near the combustion device is used to obtain the ignition source power during the localized / complete burning phase. Based on the ignition source power, the change in flame radiation flux of the combustion device's ignition source over horizontal distance is calculated. After the cylinder is vented, the jet flame formed by the high-pressure hydrogen increases the external radiation flux. The state parameters of the hydrogen at the vent are calculated based on the venting pressure to obtain the combustion heat release rate and jet flame length. Several point sources are selected evenly distributed along the central axis of the jet flame according to the flame length. The change in flame radiation in the horizontal direction of the jet flame is calculated based on the weight of each point source. The ignition source radiation of the combustion device and the radiation of the jet flame are superimposed to obtain the total external radiation flux. The risk distance is then assessed based on the personnel radiation hazard threshold.

[0060] To facilitate the implementation of the assessment method of this invention, a combustion device for assessing the radiation hazard of a venting flame from a high-pressure hydrogen storage cylinder is designed, such as... Figure 2As shown: The system includes a rectangular support 10, on which two sets of combustion components are symmetrically arranged. Each combustion component includes parallel and independent gas pipelines 8, and a mass flow controller 3 connected to the gas pipelines 8. Each gas pipeline 8 is a pipe with one open end and one closed end, and several gas nozzles 8a connected to the gas pipeline 8 are provided. The open end of each gas pipeline 8 is connected to the fuel supply end 1 via the mass flow controller 3 and a buffer tank 2. Ignition electrodes 4 are installed between the gas pipelines 8. 4 is electrically connected to the ignition transformer 5; a hydrogen storage cylinder fixing beam 9 is provided above the rectangular bracket 10. The hydrogen storage cylinder fixing beam 9 is set perpendicular to the layout direction of the gas pipeline 8. The hydrogen storage cylinder fixing beam 9 is provided with a fixing slot 9a, which is used to place the hydrogen storage cylinder in the fixing slot 9a and fix it by conventional fixing means, so that the high-pressure hydrogen storage cylinder is set parallel to the gas pipeline 8 and the head and tail of the high-pressure hydrogen storage cylinder are respectively located above the two sets of combustion components; a thermal radiation flow meter 6 is respectively installed on the outer side of the long side and the short side of the rectangular bracket 10. Figure 2 The system incorporates three thermal radiation flow meters: two are positioned on the outer side of the long side of the rectangular support 10, distributed in the middle of the two combustion assemblies; and one is positioned on the outer side of the short side of the rectangular support 10 corresponding to the head of the high-pressure hydrogen storage cylinder. The thermal radiation flow meters 6 are connected to the data acquisition unit 7 via cooling water tanks. Preferably, the gas pipeline 8 is positioned parallel to the long side of the rectangular support 10, with the closed end of the gas pipeline 8 located in the middle of the rectangular support 10. The hydrogen storage cylinder fixing beam 9 is fixed to the middle of the rectangular support 10.

[0061] When a partial fire test is conducted on a high-pressure hydrogen storage cylinder, the mass flow controller 3 controls some or all of the gas pipelines 8 of a set of combustion components located at the tail of the high-pressure hydrogen storage cylinder to be connected to fuel and turns on the ignition switch to generate an ignition source; when a whole fire test is conducted on a high-pressure hydrogen storage cylinder, the mass flow controller 3 controls some or all of the gas pipelines 8 of the two sets of combustion components located at the tail of the high-pressure hydrogen storage cylinder to be in the open state and turns on the ignition switch to generate an ignition source.

[0062] Based on this combustion device, the present invention provides a method for assessing the radiation hazard of a high-pressure hydrogen storage cylinder venting flame, such as... Figure 1 As shown, the specific steps include:

[0063] S1. Conduct a fire test on the high-pressure hydrogen storage cylinder: The high-pressure hydrogen storage cylinder is ignited using a combustion device; this includes the following steps:

[0064] S101. Calculate the radiation flux at the target test point during the localized combustion stage: A high-pressure hydrogen storage cylinder is locally ignited, so that the flame source generated by the combustion device surrounds the tail of the high-pressure hydrogen storage cylinder. A sampling point is set up outside the flame source, and a radiation heat flux meter is installed at the sampling point to record the flame radiation flux. The flame source power during the localized combustion stage is calculated based on the flame radiation flux and the area of ​​the flame source region generated by the combustion device. Multiple target test points are set up horizontally outside the flame source, from near to far. M represents the number of target test points; the power of each target test point is obtained through the fire source power. Local fire radiation flux Record each target test point Localized fire radiation flux That is, the radiation flux distribution during the local fire stage is obtained;

[0065] S102. Calculate the radiation flux at the target test points during the overall combustion phase: The high-pressure hydrogen storage cylinder is subjected to overall combustion, ensuring the flame source generated by the combustion device completely envelops the cylinder. A sampling point is set up outside the flame source, and a radiation heat flux meter is installed at each sampling point to record the flame radiation flux. The flame source power during the overall combustion phase is calculated based on the flame radiation flux and the area of ​​the flame source region generated by the combustion device. The radiation flux at each target test point is then used to obtain the radiation flux at the target test points. Overall fire radiation flux Record each target test point Overall fire radiation flux Thus, the radiation flux distribution during the overall fire phase was obtained;

[0066] The power of the fire source during the localized burning stage in step S101:

[0067] (1)

[0068] (2)

[0069] in, This refers to the fire source power during the localized fire stage. This refers to the flame radiation flux obtained by the thermal radiation flowmeter at the sampling point during the localized fire stage.

[0070] This refers to the fire source power during the overall burning phase. This refers to the flame radiation flux obtained by the thermal radiation flowmeter at the collection point during the overall combustion phase. Atmospheric transmittance; The radiation fraction from the ignition source varies depending on the type of fuel. The preferred range is 0.15-0.25; For fire source perspective factors; This refers to the area of ​​the fire source region generated by the combustion device during the localized fire stage. The area of ​​the fire source region generated by the combustion device during the overall combustion stage;

[0071] This refers to the area of ​​the fire source region generated by the combustion device during the localized fire stage, i.e.: It is the rectangular area formed by the fuel gas pipeline in a set of combustion components located below the tail of the high-pressure hydrogen storage cylinder.

[0072] This refers to the area of ​​the fire source region generated by the combustion device during the overall combustion stage, i.e.: It is the rectangular area formed by the gas pipelines carrying fuel in the two sets of combustion components of the combustion device.

[0073] When calculating the fire source power during the local burning stage and the fire source power during the overall burning stage using general formulas (1) and (2) respectively, the average value method can be used: for example, the flame radiation flux can be calculated using general formula (1) by selecting heat radiation flow meters from different collection points. , will twice The average value is taken to improve the accuracy of the fire source power during the localized fire stage.

[0074] Target test point Localized fire radiation flux and overall fire radiation flux Method:

[0075] (3)

[0076] (4)

[0077] Because the fire source perspective factor F is affected by the relative positions of the target point (including the acquisition point and the target test point) and the fire source, it is necessary to establish coordinate values ​​in a coordinate system with the center of the fire source as the origin to obtain the fire source perspective factor F at different distances. This includes the following steps:

[0078] A. Determining the Flame Combustion Surface: The plane containing the flame source area of ​​the combustion device is taken along the axial direction of the hydrogen storage cylinder as the length direction of the flame source, and along the radial direction of the hydrogen storage cylinder as the width direction of the flame source; the direction perpendicular to the plane containing the flame source area is taken as the height direction of the flame source; a cuboid model is established using the flame source length, flame source width, and flame source height as the length, width, and height of the flame source area of ​​the combustion device; the vertical planes containing the width and height of the cuboid model are taken as the combustion surface: (e.g., ...) Figure 3 As shown.

[0079] B. Coordinate System Establishment: Establish coordinate systems according to the different positions of the target points in the field to be measured: Wherein, for formulas (1) and (2), the target points in the field to be measured are the acquisition points; for formulas (3) and (4), the target points in the field to be measured are the test points of each target. ;

[0080] When the target point in the external field to be measured is set in the radial direction of the hydrogen storage cylinder, a three-dimensional rectangular coordinate system is established with the width direction of the fire source as the X-axis, the length direction of the fire source as the Y-axis, the height direction of the fire source as the Z-axis, and the center of the combustion surface as the origin.

[0081] When the target point in the external field is located along the axial direction of the hydrogen storage cylinder, a three-dimensional rectangular coordinate system is established with the length of the fire source as the X-axis, the width of the fire source as the Y-axis, the height of the fire source as the Z-axis, and the center of the combustion surface as the origin; (e.g.) Figure 3 (as shown);

[0082] C. Determination of the fire source perspective factor F:

[0083]

[0084] Where x is the vertical distance between the target point in the external field to be measured and the combustion surface, y1 and y2 are the intercepts of the combustion surface on the Y-axis, and z1 and z2 are the intercepts of the combustion surface on the Z-axis.

[0085] S2. Obtain the jet fire heat release rate and jet fire length during the cylinder venting stage: The high-pressure hydrogen storage cylinder is ignited until the safety pressure relief device is activated, causing the hydrogen storage cylinder to vent and emit a jet fire; the heat release rate of the jet fire is obtained through the venting critical pressure of the hydrogen storage cylinder. With the length L of the jet fire f :

[0086] Heat release rate for:

[0087]

[0088] in, The hydrogen flow rate at the vent nozzle is obtained from the following formula:

[0089]

[0090] d is the diameter of the vent of the hydrogen storage cylinder, ΔH is the heat of hydrogen combustion, π is a constant, and p0 is the maximum pressure value of the cylinder before venting. R is the adiabatic coefficient; T is the hydrogen gas constant; b is the hydrogen temperature at the vent nozzle; K is the control volume constant; and K is the loss coefficient for hydrogen venting. p ΔT represents the specific heat capacity at constant pressure of hydrogen; ΔT represents the temperature drop during the hydrogen flow process.

[0091] Jet fire length for:

[0092]

[0093] in, To release the hydrogen density at the nozzle; The density of the outside air; This is the ratio for the complete combustion reaction of hydrogen.

[0094] S3, based on the heat release rate of the jet fire and jet fire length The target test points were obtained. The distribution of radiant flux of the flame during the gas cylinder release phase includes the following steps:

[0095] S301, such as Figure 4 : In the jet fire length L f N flame point sources are selected sequentially along the central axis of the jet flame within the range. Let i = 1, 2, ..., N, and ensure that each flame point source is evenly distributed; typically .

[0096] S302, Based on the heat release rate of the jet fire Identify each flame source At the target test point Incident radiant flux of the jet flame at the location :

[0097]

[0098] Among them, D i flame point source With the target test point The distance between them; Indicates flame source and target test points The angle between the line connecting the two sides and the horizontal plane; Atmospheric transmittance; Let be the fraction of jet fire radiation, where The preferred range is: 0.1-0.2; w i flame point source Weighted strength N represents the total number of flame sources; n represents the number of heat sources within the first 0.75N.

[0099] S4. Obtain the total radiative flux at the target test points during the gas cylinder release phase: [The text abruptly ends here, likely due to an incomplete sentence or a missing section.] Radiation flux during the overall fire phase and incident radiation flux of jet flame By summing the corresponding values, we can obtain the target test points. Total radiant flux after gas cylinder venting ;

[0100] S5. Based on the target test points of the fire stage. The radiation flux at the target test point and the total radiation flux at the target test point after the gas cylinder is released are used to determine the danger zone of the target test point:

[0101] when At that time, the target test point It is in a danger zone during the localized fire stage;

[0102] when At that time, the target test point The area is in a safe zone during the localized fire stage;

[0103] when At that time, the target test point It is in a danger zone during the overall fire stage;

[0104] when At that time, the target test point The area was in a safe zone during the overall fire phase;

[0105] when At that time, the target test point The area is in danger during the gas cylinder release phase;

[0106] when At that time, the target test point The gas cylinder is in a safe zone during the venting phase.

[0107] The embodiments of the invention are further described through the following burning process of gas cylinders of specific specifications. It should be noted that the embodiments of the present invention are not limited to this example:

[0108] Taking a 140 L-35 MPa high-pressure hydrogen storage cylinder as an example, the relevant specifications and fire test parameters of the high-pressure hydrogen storage cylinder are shown in Table 1.

[0109] Table 1 Specifications of High-Pressure Hydrogen Storage Cylinders

[0110]

[0111] S1. Fire test on high-pressure hydrogen storage cylinder: The high-pressure hydrogen storage cylinder is ignited using a combustion device. First, the combustion device is arranged with the LPG cylinder connected to the buffer tank 2 as the fuel supply end 1. The high-pressure hydrogen storage cylinder is fixed to the hydrogen storage cylinder fixing beam 9 using a hydrogen storage cylinder fixing clamp, ensuring that the head and tail of the high-pressure hydrogen storage cylinder are positioned above the two sets of combustion components, respectively. Figure 2 As shown, the head of the high-pressure hydrogen storage cylinder is positioned in the front half of the combustion device, and the tail of the high-pressure hydrogen storage cylinder is positioned in the rear half of the combustion device. The high-pressure hydrogen storage cylinder is then secured to the hydrogen storage cylinder fixing beam 9 using a fixing device.

[0112] S101. Calculate the radiation flux at the target test point during the localized fire stage: First, start the combustion components of the rear half of the combustion device and adjust the mass flow controller 3 to turn on the ignition switch so that the tail of the high-pressure hydrogen storage cylinder can be completely enveloped by the flame. Calculate the fire source power during the localized fire stage using the general formula (1) based on the parameters recorded by the radiation heat flow meters set around the combustion device. When calculating, the average value method can be used: that is, select the data from the heat flow meters at two collection points close to the fire source to calculate the flame radiation flux. , will twice The average value is taken to improve the accuracy of the fire source power during the localized fire stage.

[0113] After obtaining the fire source power during the localized fire stage, the test points for each target can be obtained according to general formula (3). Localized fire radiation flux The result will be By saving the records, we can obtain the target test points from near to far from the fire source under the condition of localized fire. The distribution of radiation flux.

[0114] S102. Calculate the radiation flux at the target test point during the overall combustion stage: Start the combustion components of the front half of the combustion device so that both the front and rear combustion components of the combustion device are in the starting state. After the high-pressure hydrogen storage cylinder is switched from local combustion to overall combustion, calculate the fire source power of the overall combustion stage according to the parameters recorded by the radiation heat flow meters set around the combustion device using general formula (1). After obtaining the fire source power of the overall combustion stage, the power of each target test point can be obtained according to general formula (4). Localized fire radiation flux The result will be By saving the record, we can obtain the test points of each target, from closest to furthest from the fire source, under the overall burning condition. The distribution of radiation flux.

[0115] The method for determining the fire source perspective factor F in general formulas (1), (2), (3), and (4) includes the following steps:

[0116] A. Determining the flame combustion surface: For the combustion device in this invention, such as Figure 3 As shown: the long side of the rectangle of the combustion device is the length direction of the fire source, the short side of the rectangle of the combustion device is the width direction of the fire source; the direction perpendicular to the upper surface of the combustion device is the height direction of the fire source.

[0117] When a high-pressure hydrogen storage cylinder is partially burned, a cuboid model is established with the length of the gas pipeline in a set of combustion components as the length, the width corresponding to the number of gas pipelines carrying fuel in a set of combustion components below the tail of the high-pressure hydrogen storage cylinder as the width, and the height of the resulting flame as the height.

[0118] When the high-pressure hydrogen storage cylinder is burned as a whole, the gas pipelines in both sets of combustion components are partially or completely filled with fuel. Therefore, a cuboid model is established with the total length of the gas pipelines in the two sets of combustion components as the length, the width based on the number of gas pipelines filled with fuel in the combustion components as the width, and the height of the formed flame as the height.

[0119] The vertical plane containing the width and height of the cuboid model is the combustion surface:

[0120] B. Establishing the coordinate system: (e.g.) Figure 3 As shown, a three-dimensional rectangular coordinate system is established with the width direction of the fire source as the Y-axis, the height direction of the fire source as the Z-axis, the length direction of the fire source as the X-axis, and the center of the burning surface as the origin.

[0121]

[0122] Where x is the vertical distance between the target point to be tested and the combustion surface, and in formula (1), the target point to be tested is the sampling point set during the local burning stage, and in formula (2), the target point to be tested is the sampling point set during the overall burning stage; in formulas (3) and (4), the target point to be tested is the target test point. ;

[0123] y1 and y2 are the intercepts of the burning surface on the Y-axis (in fact, the coordinates of y1 and y2 are half the width of the fire source, such as...). Figure 3 As shown, (y2 is a positive value, y1 is a negative value), z1 and z2 are the intercepts of the combustion surface on the Z-axis. Similarly, z1 and z2 are half the height of the fire source (z2 is a positive value, z1 is a negative value).

[0124] like Figure 5 As shown: According to the requirements of Phase II of the Global Technical Regulations for the Safety of Fuel Cell Electric Vehicles, if the specific heat power of the local fire source is determined based on the parameters of the radiative heat flux meter... 300 kW / m 2 The area of ​​the burning zone is 0.16 m². 2 The calculated radiative flux of the combustion device's ignition source in the external field reaches 4 kW / m². 2 The distance is 1.6-2.1 m, reaching 1.6 kW / m. 2 The distance is 2.6-3.4 m.

[0125] When the fire transitions to a uniform combustion state, if the specific heat power of the overall fire source is determined based on the parameters of the radiation heat flux meter... 700kW / m 2 The combustion zone is approximately 0.85 m. 2 The radiant flux of the combustion device's ignition source in the external field reaches 4 kW / m². 2 The distance is 3.5-6.5 m, reaching 1.6 kW / m. 2 The distance is 5.5-10.2 m.

[0126] S2. Obtain the heat release rate and length of the jet flame during the cylinder venting phase: After the high-pressure hydrogen storage cylinder is vented, the resulting jet flame increases external radiation. The heat release rate and length of the jet flame are calculated based on parameters such as the cylinder venting pressure. The calculation is based on the cylinder pressure reaching 1.2 times the nominal pressure before venting. For example, with a 140L-35 MPa high-pressure hydrogen storage cylinder, the highest pressure before venting is 42 MPa.

[0127] Based on the relationship between the gas cylinder release pressure and the hydrogen release flow rate, the hydrogen flow rate u at the release nozzle can be obtained:

[0128]

[0129] p0 is the maximum pressure value of the gas cylinder before venting; γ is the adiabatic coefficient; R is the hydrogen gas constant; T is the hydrogen temperature at the venting nozzle; b represents the control volume constant; K is the loss coefficient of hydrogen venting; c p ΔT represents the specific heat capacity at constant pressure of hydrogen; ΔT represents the temperature drop during the hydrogen flow process.

[0130] The heat release rate can be obtained from the hydrogen flow velocity u at the vent nozzle. for:

[0131]

[0132] d is the diameter of the vent of the hydrogen storage cylinder, ΔH is the heat of hydrogen combustion, and π = 3.14 is a constant.

[0133] Jet fire length L f for:

[0134]

[0135] Among them, L f The flame length is in meters (m). The density of hydrogen gas at the vent nozzle is kg / m³. 3 ; The density of outside air, kg / m³ 3 ; This is the ratio for the complete combustion reaction of hydrogen.

[0136] S3, based on the heat release rate of the jet fire and jet fire length To obtain each target test point The distribution of radiant flux of the flame during the gas cylinder release phase includes the following steps:

[0137] S301, at the jet fire length L f Twenty flame points were selected sequentially along the central axis of the jet flame within the range. This ensures that each flame point source is evenly distributed. Specifically, let... Located at the bottom of the jet flame, Located at the tip of the jet flame. The location of each flame point source is used to determine the relationship between each flame point source and the target test point. The straight-line distance and the angle between the line connecting the straight-line distances and the horizontal direction.

[0138] S302, Based on the heat release rate of the jet fire Identify each flame source At the target test point Incident radiation flux at point :

[0139]

[0140] Among them, D i flame point source With the target test point The distance between them; Representing each flame source and target test points The angle between the line connecting the two sides and the horizontal direction; Atmospheric transmittance; For jet fire radiation fraction; w i Weighted intensity of each flame point source N represents the total number of flame sources; n represents the number of heat sources within the first 0.75N.

[0141] S4. At each target test point... Radiation flux during the overall fire phase Incident radiation flux during the gas cylinder release phase By summing the corresponding values, we can obtain the target test points. Total radiant flux after gas cylinder venting ,Right now:

[0142]

[0143] Based on the results, Reaching 4 kW / m2 The distance is 11.5-14 m, reaching 1.6 kW / m. 2 The distance is 21.6-25 m.

[0144] S5. Based on the target test points of the fire stage. The radiation flux at the target test point and the total radiation flux at the target test point after the gas cylinder is released are used to determine the danger zone of the target test point:

[0145] when At that time, the target test point It is in a danger zone during the localized fire stage;

[0146] when At that time, the target test point The area is in a safe zone during the localized fire stage;

[0147] when At that time, the target test point It is in a danger zone during the overall fire stage;

[0148] when At that time, the target test point The area was in a safe zone during the overall fire phase;

[0149] when At that time, the target test point The area is in danger during the gas cylinder release phase;

[0150] when At that time, the target test point The gas cylinder is in a safe zone during the venting phase.

[0151] The above description, in conjunction with specific preferred technical solutions, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for evaluating the fire radiation hazard of a high-pressure hydrogen storage cylinder discharge, characterized by, Includes the following steps: S1. Conduct a fire test on the high-pressure hydrogen storage cylinder: Use a combustion device to provide an ignition source to burn the high-pressure hydrogen storage cylinder. Includes the following steps: S101. Calculate the radiation flux at the target test point during the localized combustion stage: Perform localized combustion on the high-pressure hydrogen storage cylinder, set up a sampling point outside the fire source, and install a radiation heat flux meter at the sampling point to record the flame radiation flux; calculate the fire source power during the localized combustion stage based on the flame radiation flux and the area of ​​the fire source region generated by the combustion device; set up multiple target test points horizontally outside the fire source from near to far. , M The number of target test points; the target test points are obtained through the power of the fire source. Local fire radiation flux Record each of the target test points. Localized fire radiation flux The radiation flux distribution during the local fire phase was obtained. S102, calculating the radiation flux at the target test points in the overall fire burning stage: the high-pressure hydrogen storage cylinder is subjected to overall fire burning, so that the fire source generated by the combustion device completely wraps the high-pressure hydrogen storage cylinder, a collection point is arranged outside the fire source, a radiation heat flow meter is arranged at the collection point to record the flame radiation flux; the flame radiation flux and the area of the fire source region generated by the combustion device are used to calculate the fire source power in the overall fire burning stage; the overall fire burning radiation flux at each target test point is obtained through the fire source power ; the overall fire burning radiation flux of each target test point is recorded to obtain the radiation flux distribution in the overall fire burning stage;​​ S2. Obtain the jet fire heat release rate and jet fire length during the cylinder venting stage: The high-pressure hydrogen storage cylinder is ignited until the safety pressure relief device is activated, causing the hydrogen storage cylinder to vent and emit a jet fire; the heat release rate of the jet fire is obtained through the venting critical pressure of the hydrogen storage cylinder. With the length of the jet fire : The heat release rate for: ； in, The hydrogen flow rate at the vent nozzle is obtained from the following formula: ； Δ is the diameter of the vent of the hydrogen storage cylinder. H The heat of hydrogen combustion, It is a constant. p 0 This is the maximum pressure value before the gas cylinder is released; The adiabatic coefficient; R The gas constant for hydrogen; T To release the hydrogen temperature at the nozzle; b Indicates the control volume constant; K This is the loss coefficient due to hydrogen leakage; c p Δ is the specific isobaric heat capacity of hydrogen. T This represents the temperature drop during the hydrogen flow process; Jet fire length for: ； in, To release the hydrogen density at the nozzle; The density of the outside air; This is the ratio for the complete combustion reaction of hydrogen. S3, based on the heat release rate of the jet fire With the length of the jet fire The target test points were obtained. The distribution of jet fire radiation flux during the gas cylinder release phase includes the following steps: S301, in the length of the jet fire Select sequentially along the central axis of the jet flame within the range. N One flame point source , i=1,2,……,N, and make each of the flame point sources uniformly distributed; S302, Based on the heat release rate of the jet fire Identify each flame source At the target test point Incident radiative flux of the jet flame at the location : ； in, D i flame point source With the target test point The distance between them; Indicates flame source and target test points The angle between the line connecting the two sides and the horizontal plane; Atmospheric transmittance; For jet fire radiation fraction; w i flame point source Weighted strength N represents the total number of flame sources; This represents the number of heat source points within the first 0.75N. S4. Obtain the total radiative flux at the target test points during the gas cylinder release phase: [The text abruptly ends here, likely due to an incomplete sentence or a missing section.] Radiation flux during the overall fire phase and incident radiation flux of jet flame By summing the corresponding values, we can obtain the target test points. Total radiant flux after gas cylinder venting ; S5. Based on the radiation flux at the target test point during the fire stage and the total radiation flux at the target test point after the gas cylinder is released, determine the danger zone of the target test point: when q l ( t m >4kW / m 2 At that time, the target test point It is in a danger zone during the localized fire stage; when q l ( t m <1.6kW / m 2 At that time, the target test point The area is in a safe zone during the localized fire stage; when q w ( t m >4kW / m 2 At that time, the target test point It is in a danger zone during the overall fire stage; when q w ( t m <1.6kW / m 2 At that time, the target test point The area was in a safe zone during the overall fire phase; when q total ( t m >4kW / m 2 At that time, the target test point The area is in danger during the gas cylinder release phase; when q total ( t m <1.6kW / m 2 At that time, the target test point The gas cylinder is in a safe zone during the venting phase.

2. The method for assessing the radiation hazard of a high-pressure hydrogen storage cylinder venting flame according to claim 1, characterized in that, In step S101, the fire source generated by the combustion device during localized fire envelops the tail of the high-pressure hydrogen storage cylinder.

3. The method for assessing the radiation hazard of a high-pressure hydrogen storage cylinder venting according to claim 1, characterized in that, The fire source power in step S1 during the localized fire stage and the overall fire stage is: ； ； in, This refers to the fire source power during the localized fire stage. This represents the flame radiation flux obtained from the thermal radiation flowmeter at the sampling point during the localized fire stage. This refers to the fire source power during the overall burning phase. The flame radiation flux obtained by the thermal radiation flowmeter at the collection point during the overall combustion stage; Atmospheric transmittance; The fire source radiation fraction; For fire source perspective factors; This refers to the area of ​​the fire source region generated by the combustion device during the localized fire stage. This refers to the area of ​​the fire source region generated by the combustion device during the overall combustion stage.

4. The method for assessing the radiation hazard of a high-pressure hydrogen storage cylinder venting according to claim 3, characterized in that, The target test point Localized fire radiation flux and overall fire radiation flux Method: ； 。 5. The method for assessing the radiation hazard of a high-pressure hydrogen storage cylinder venting flame according to claim 3 or 4, characterized in that, Fire source perspective factor The method for determining this includes the following steps: A. Determining the flame combustion surface: The plane containing the fire source area of ​​the combustion device is taken along the axial direction of the hydrogen storage cylinder as the length direction of the fire source, and along the radial direction of the hydrogen storage cylinder as the width direction of the fire source; the direction perpendicular to the plane containing the fire source area is taken as the height direction of the fire source; a cuboid model is established with the fire source length, fire source width, and flame height formed by the fire source area of ​​the combustion device as the length, width, and height; wherein, the plane containing the width and height of the cuboid model is taken as the combustion surface; B. Coordinate System Establishment: A coordinate system is established according to the different positions of the target points in the external field to be measured. The target points in the external field to be measured include the acquisition points and the target test points. When the target point in the external field to be measured is set in the radial direction of the hydrogen storage cylinder, a three-dimensional rectangular coordinate system is established with the width direction of the fire source as the X-axis, the length direction of the fire source as the Y-axis, the height direction of the fire source as the Z-axis, and the center of the combustion surface as the origin. When the target point in the field to be measured is located in the axial direction of the hydrogen storage cylinder, a three-dimensional rectangular coordinate system is established with the length direction of the fire source as the X-axis, the width direction of the fire source as the Y-axis, the height direction of the fire source as the Z-axis, and the center of the combustion surface as the origin. C. Determine the fire source perspective factor F: ； in, x The vertical distance between the target point in the external field to be measured and the combustion surface; y 1 , y 2 The intercept of the combustion surface on the Y-axis. z 1 、z 2 The intercept of the combustion surface on the Z-axis.

6. The method for assessing the radiation hazard of a high-pressure hydrogen storage cylinder venting according to claim 1, characterized in that, 。

Images