High-pressure hydrogen storage cylinder flame discharge radiation risk assessment method and combustion device

Abstract

The invention discloses a high-pressure hydrogen storage cylinder flame discharge radiation risk assessment method and a combustion device. The method comprises the steps that S1, a burning test is conducted on a high-pressure hydrogen storage cylinder; s2, the jet fire heat release rate and the jet fire length in the gas cylinder release stage are obtained; s3, according to the heat release rate of the jet fire and the length of the jet fire, the jet fire radiation flux distribution condition of each target test point tm in the gas cylinder release stage is obtained; s4, obtaining the total radiation flux at the target test point in the gas cylinder discharge stage; and judging the dangerous area of the target test point according to the radiation flux at the target test point in the burning stage and the total radiation flux of the target test point after the gas cylinder is discharged. According to the method, the flame external field radiation in the burning process of the high-pressure hydrogen storage cylinder is predicted, the dangerous distance is judged based on the personnel radiation injury threshold value, and a theoretical basis is provided for personnel risk early warning in the burning scene of the high-pressure hydrogen storage cylinder.

Description

Technical Field

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

[0002] In response to climate change caused by excessive consumption of primary energy, countries around the world are actively carrying out energy transformation to solve environmental pollution and greenhouse effect problems. Hydrogen energy has the advantages of high calorific value, no pollution, and high conversion rate, and is a direction with great development potential in the future energy field. Under the strategic background of the "dual carbon" policy, my country is also vigorously promoting the layout of the hydrogen energy industry. Especially in the field of transportation, new energy vehicles that use hydrogen fuel cells instead of traditional internal combustion engines are gradually gaining popularity in the consumer market. Hydrogen fuel cell vehicles mainly use high-pressure hydrogen storage cylinders to store gaseous hydrogen and transport it to the fuel cell to react with air to generate electricity to drive the vehicle. The reaction product is only water, which will not pollute the environment and cause additional carbon emissions. With the support of national policies, hydrogen fuel cell vehicle-related technologies and industries will continue to develop rapidly and bring greater benefits to my country's economic development and environmental protection.

[0003] Since fuel cell vehicles are prone to fire due to collision and circuit problems, the fire safety of their hydrogen storage systems is a key issue of concern to the industry. Although the first phase of the global technical regulations for the safety of fuel cell electric vehicles stipulates that on-board high-pressure hydrogen storage cylinders should be subjected to fire tests to verify their emergency discharge process under fire, due to the lack of regulations on the fire system in the first phase of the regulations, the system has not been able to achieve effective regulation and consistency in terms of flame stability, fire area conversion, and fire source power. No solution has been found in the prior art that can identify the risk of flame thermal radiation damage during the fire process of high-pressure hydrogen storage cylinders and quickly assess the danger distance of personnel. Summary of the invention

[0004] The purpose of the present invention is to provide a method and a combustion device for evaluating the radiation hazard of the flame released from a high-pressure hydrogen storage cylinder, which can quickly predict the fire stage and the external field radiation distribution of the flame released from a high-pressure hydrogen storage cylinder and evaluate the safety distance of the flame to personnel.

[0005] The present invention solves the technical problems of the prior art by adopting a technical solution: a method for assessing the radiation hazard of flame release from a high-pressure hydrogen storage cylinder, comprising the following steps:

[0006] S1. Fire test on high-pressure hydrogen storage cylinders: Provide a fire source through a combustion device to burn the high-pressure hydrogen storage cylinders; including the following steps:

[0007] S101. Calculate the radiation flux at the target test point in the local burning stage: perform local burning on the high-pressure hydrogen storage cylinder, set a collection point outside the fire source, and set a radiation heat flux meter at the collection point to record the flame radiation flux; calculate the fire source power in the local burning stage according to the flame radiation flux and the area of ​​the fire source area generated by the combustion device; set multiple target test points {t m |1≤m≤M}, M is the number of target test points; each target test point t is obtained by the fire source power m The local fire radiation flux q l (t m );Record each of the target test points t m The local fire radiation flux q l (t m ), and obtain the radiation flux distribution in the local burning stage;

[0008] S102, calculating the radiation flux at the target test point in the overall burning stage: the high-pressure hydrogen storage cylinder is burned as a whole, so that the fire source generated by the combustion device completely covers the high-pressure hydrogen storage cylinder, and a collection point is set outside the fire source, and a radiation heat flux meter is set at the collection point to record the flame radiation flux; the fire source power in the overall burning stage is calculated according to the flame radiation flux and the area of ​​the fire source area generated by the combustion device; the fire source power at each of the target test points is obtained by the fire source power. m The overall fire radiation flux q w (t m );Record each of the target test points t m The overall fire radiation flux q w (t m ), and obtain the radiation flux distribution of the overall burning stage;

[0009] S2. Obtain the jet fire heat release rate and jet fire length during the cylinder release stage: The high-pressure hydrogen storage cylinder is burned until the safety pressure relief device of the hydrogen storage cylinder is activated, so that the hydrogen storage cylinder releases jet fire; the jet fire heat release rate Q and jet fire length L are obtained through the release critical pressure of the hydrogen storage cylinder. f :

[0010] The heat release rate Q is:

[0011]

[0012] Where u is the hydrogen flow rate at the discharge nozzle, which is obtained by the following relationship:

[0013]

[0014] d is the discharge port diameter of the hydrogen storage cylinder, ΔH is the heat of hydrogen combustion, π is a constant, p0 is the maximum pressure value of the cylinder before discharge; γ is the adiabatic coefficient; R is the hydrogen gas constant; T is the hydrogen temperature at the discharge nozzle; b represents the control volume constant; K is the loss coefficient of hydrogen discharge; c p is the specific heat capacity of hydrogen at constant pressure; ΔT is the temperature drop during the hydrogen flow process;

[0015] Jet fire length L f for:

[0016]

[0017] Where, ρ is the hydrogen density at the discharge nozzle; ρ ∞ is the external air density; f s The ratio for complete combustion reaction of hydrogen;

[0018] S3, according to the jet fire heat release rate Q and jet fire length L f , get each target test point t m The jet fire radiation flux distribution during the cylinder release phase includes the following steps:

[0019] S301, in the jet fire length L f N flame point sources {p i}, i=1, 2, ..., N, and each of the flame point sources is evenly distributed;

[0020] S302, determine each flame point source p according to the heat release rate Q of the jet fire i At the target test point t m The incident radiation flux q of the jet flame at f (t m ):

[0021]

[0022] Among them, D i is the flame point source p i With the target test point t m The distance between i represents the flame point source p i and the target test point t m is the angle between the line connecting the two planes and the horizontal plane; τ is the atmospheric transmittance; χ f is the jet fire radiation fraction; w i is the flame point source p i Weighted intensity 0.625% ≤ w i ≤9.375%; N is the total number of flame point sources; n is the number of heat source points before 0.75N;

[0023] S4. Obtain the total radiation flux at the target test point during the cylinder release phase: t m The radiation flux q during the overall burning phase w (t m ) and the jet flame incident radiation flux q f (t m ) to obtain the corresponding sum of each target test point t m The total radiation flux after the cylinder is released is q total (t m );

[0024] S5. According to the radiation flux at the target test point during the fire phase and the total radiation flux at the target test point after the gas cylinder is released, the dangerous area of ​​the target test point is judged:

[0025] When l (t m )>4kW / m -2 When the target test point t m In the danger zone during the localized burn stage;

[0026] When l (t m )<1.6kW / m -2 When the target test point t m In the safe zone during the localized fire stage;

[0027] When w (t m )>4kW / m -2 When the target test point t m In the danger zone during the overall fire stage;

[0028] When w (t m )<1.6kW / m -2 When the target test point t m In the safe zone during the overall fire stage;

[0029] When total (t m )>4kW / m -2 When the target test point t m Being in the danger zone during the cylinder release phase;

[0030] When total (t m )<1.6kW / m -2 When the target test point t m Be in the safe zone during the cylinder release phase.

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

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

[0033]

[0034] Among them, P l is the fire source power in the local fire stage, is the flame radiation flux obtained by the thermal radiation flowmeter at the collection point during the local burning stage, P w is the fire source power during the overall burning stage, is the flame radiation flux obtained by the thermal radiation flowmeter at the collection point during the overall burning stage; τ is the atmospheric transmittance; χ b is the fire source radiation fraction; F is the fire source viewing angle factor; It is the area of ​​the fire source area generated by the combustion device during the local fire stage. It is the area of ​​the fire source region generated by the combustion device during the overall burning stage;

[0035] The target test point t m The local fire radiation flux q l (t m ) and the overall fire radiation flux q w (t m ) method:

[0036]

[0037] The method for determining the fire source viewing angle factor F comprises the following steps:

[0038] A. Determination of flame combustion surface: The plane where the fire source area of ​​the combustion device is located along the axial direction of the hydrogen storage cylinder is taken as the length direction of the fire source, and the plane along the radial direction of the hydrogen storage cylinder is taken as the width direction of the fire source; the direction perpendicular to the plane where the fire source area is located is taken as the height direction of the fire source; a rectangular parallelepiped model is established with the fire source length, fire source width and flame height formed in the fire source area of ​​the combustion device as the length, width and height; wherein, the plane where the width and height of the rectangular parallelepiped model are located is taken as the combustion surface:

[0039] B. Establishment of coordinate system: Establish a coordinate system according to the different positions of the external field target points to be measured, wherein the external field target points to be measured include the acquisition points and the target test points:

[0040] When the external field target point 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;

[0041] When the external field target point to be measured is located in the axial direction of the hydrogen storage cylinder, the length direction of the fire source is taken as the X-axis, the width direction of the fire source is taken as the Y-axis, the height direction of the fire source is taken as the Z-axis, and the center of the burning surface is taken as the origin to establish a three-dimensional rectangular coordinate system;

[0042] C. Determine the fire source viewing angle factor F:

[0043]

[0044] Among them, x is the vertical distance between the external field target point to be measured and the combustion surface; y1, y2 are the intercepts of the combustion surface on the Y axis, and z1, z2 are the intercepts of the combustion surface on the Z axis.

[0045] N≥20.

[0046] The combustion device used for the method of evaluating the radiation hazard of the flame released from the high-pressure hydrogen storage cylinder comprises a rectangular bracket, on which two groups of combustion components are fixed, and the two groups of combustion components are symmetrically arranged; the combustion components comprise gas pipelines arranged in parallel with each other, and a mass flow controller connected to the gas pipeline; the gas pipeline is a pipe body with one end open and the other end closed, and the gas pipeline is provided with a plurality of gas nozzles connected to the gas pipeline; the open end of each gas pipeline is connected to the fuel supply end through the mass flow controller via the buffer tank; points are installed between the gas pipelines. The fire electrode and the ignition electrode are electrically connected to the ignition transformer; a hydrogen storage cylinder fixing beam is provided above the rectangular bracket, and the hydrogen storage cylinder fixing beam is arranged perpendicular to the laying direction of the gas pipeline. A fixing slot is provided on the hydrogen storage cylinder fixing beam, and the hydrogen storage cylinder is fixed in the fixing slot, so that the high-pressure hydrogen storage cylinder is arranged parallel to the gas pipeline and the head and tail of the high-pressure hydrogen storage cylinder are respectively located above the two groups of combustion components; thermal radiation flow meters are respectively provided on the long side and short side of the rectangular bracket, and the thermal radiation flow meters are respectively connected to the data collector through cooling water tanks.

[0047] The gas pipeline is arranged parallel to the long side of the rectangular bracket, the closed end of the gas pipeline is located in the middle of the rectangular bracket, and the hydrogen storage cylinder fixing beam is fixed to the middle of the rectangular bracket.

[0048] The beneficial effects of the present invention are as follows: the present invention performs local fire and overall fire on the high-pressure hydrogen storage cylinder, determines the external field thermal radiation of the fire stage according to the area and heat source power of the local fire and overall fire, estimates the length of the jet fire formed according to the peak pressure in the cylinder after the hydrogen storage cylinder is released, and estimates its external field thermal radiation according to the jet fire heat release rate, and based on the flame external field radiation and the human body thermal radiation injury threshold, the purpose of quickly predicting the safety distance of personnel in the high-pressure hydrogen storage cylinder release flame radiation under the fire condition is achieved. Therefore, the present invention predicts the flame external field radiation during the high-pressure hydrogen storage cylinder fire process, and determines the dangerous distance based on the personnel radiation injury threshold, providing a theoretical basis for personnel risk warning in the high-pressure hydrogen storage cylinder fire scenario. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a basic flow chart of the evaluation method of the present invention.

[0050] Figure 2 It is a schematic diagram of the structure of the combustion device in the present invention.

[0051] Figure 3 It is a schematic diagram of determining the combustion surface and establishing the coordinate system in the process of determining the fire source viewing angle factor F in the present invention.

[0052] Figure 4 Schematic diagram of the calculation of the incident radiation flux of a jet fire at any target test point.

[0053] Figure 5 This is a schematic diagram of the flame radiation risk distance during the fire process of 140L-35MPa hydrogen storage cylinders.

[0054] In the figure: 1-fuel supply end, 2-buffer tank, 3-mass flow controller, 4-ignition electrode, 5-ignition transformer, 6-thermal radiation flowmeter, 7-data collector, 8-gas pipeline, 8a-gas nozzle, 9-hydrogen storage cylinder fixing beam, 9a-fixed card slot, 10-rectangular bracket. DETAILED DESCRIPTION

[0055] The present invention is described below with reference to the accompanying drawings and specific embodiments:

[0056] The design idea of ​​the present invention is:

[0057] The combustion device is started to generate a local or overall fire source that can wrap around the high-pressure hydrogen storage cylinder, and the high-pressure hydrogen storage cylinder is partially or completely burned. The fire source power of the local / overall burning stage is obtained by using the data recorded by the radiation heat flux meter installed near the combustion device, and the flame radiation flux change of the fire source of the combustion device at the horizontal distance is calculated according to the fire source power; after the cylinder is released, the jet flame formed by the high-pressure hydrogen will increase the radiation flux of the external field, and the state parameters of the hydrogen at the discharge port are calculated according to the discharge pressure to obtain the combustion heat release rate and jet flame length of the jet flame; a number of evenly distributed point sources are selected on the central axis of the jet flame according to the flame length, and the flame radiation change of the jet flame in the horizontal direction is calculated according to the weight of each point source; the fire source radiation of the combustion device is superimposed with the radiation of the jet flame to obtain the total external field radiation flux, and the risk distance is evaluated according to the personnel radiation injury threshold.

[0058] In order to facilitate the implementation of the evaluation method of the present invention, the present invention designs a combustion device for the evaluation method of the radiation hazard of the release flame of a high-pressure hydrogen storage cylinder, such as Figure 2 As shown: it includes a rectangular bracket 10, on which two groups of combustion components are symmetrically arranged; the combustion components include gas pipelines 8 arranged in parallel and independently of each other, and a mass flow controller 3 connected to the gas pipeline 8; each gas pipeline 8 is a pipe body with one end open and the other end closed, and the gas pipeline 8 is provided with a plurality of gas nozzles 8a connected to the gas pipeline 8; the open end of each gas pipeline 8 is connected to the fuel supply end 1 through the mass flow controller 3 and the buffer tank 2; an ignition electrode 4 is installed between the gas pipelines 8, and the ignition electrode 4 is electrically connected to the ignition transformer 5; a hydrogen storage cylinder fixing beam 9 is provided above the rectangular bracket 10, and the hydrogen storage cylinder fixing beam 9 is arranged perpendicular to the layout direction of the gas pipeline 8. A fixing groove 9a is provided on the hydrogen storage cylinder fixing beam 9, which is used to place the hydrogen storage cylinder in the fixing groove 9a and fix it by conventional fixing means, and the high-pressure hydrogen storage cylinder is arranged parallel to the gas pipeline 8 and the head and tail of the high-pressure hydrogen storage cylinder are respectively located above the two groups of combustion components; the outer sides of the long side and the short side of the rectangular bracket 10 are respectively provided with a heat radiation flowmeter 6 ( Figure 2 A total of three thermal radiation flowmeters are provided: two are provided outside the long side of the rectangular bracket 10, distributed in the middle of the two groups of combustion components; one is provided outside the short side of the rectangular bracket 10 corresponding to the head of the high-pressure hydrogen storage cylinder. The thermal radiation flowmeter 6 is connected to the data acquisition device 7 through a cooling water tank. It is preferred to arrange the gas pipeline 8 parallel to the long side of the rectangular bracket 10, the closed end of the gas pipeline 8 is located in the middle of the rectangular bracket 10, and the hydrogen storage cylinder fixing beam 9 is fixed to the middle of the rectangular bracket 10.

[0059] When a local fire test is performed on a high-pressure hydrogen storage cylinder, the mass flow controller 3 is used to control part or all of the gas pipelines 8 of a group of combustion components located at the rear of the high-pressure hydrogen storage cylinder to be supplied with fuel and the ignition switch is turned on to generate a fire source; when a whole fire test is performed on the high-pressure hydrogen storage cylinder, the mass flow controller 3 is used to control part or all of the gas pipelines 8 of the two groups of combustion components located at the rear of the high-pressure hydrogen storage cylinder to be in an open state and the ignition switch is turned on to generate a fire source.

[0060] Based on the combustion device, the method for evaluating the radiation hazard of the flame released by the high-pressure hydrogen storage cylinder of the present invention is as follows: Figure 1 As shown, the specific steps include:

[0061] S1. Fire test on high-pressure hydrogen storage cylinders: Provide a fire source through a combustion device to burn the high-pressure hydrogen storage cylinders; including the following steps:

[0062] S101. Calculate the radiation flux at the target test point in the local burning stage: perform local burning on the high-pressure hydrogen storage cylinder, even if the fire source generated by the combustion device wraps the tail of the high-pressure hydrogen storage cylinder. Set a collection point outside the fire source, and set a radiation heat flux meter at the collection point to record the flame radiation flux; calculate the fire source power in the local burning stage based on the flame radiation flux and the area of ​​the fire source area generated by the combustion device; set multiple target test points {t m |1≤m≤M}, M is the number of target test points; the target test points t are obtained by the fire source power. m The local fire radiation flux q l (t m );Record each target test point t m The local fire radiation flux q l (t m ), that is, the radiation flux distribution at the local burning stage is obtained;

[0063] S102, calculating the radiation flux at the target test point in the overall burning stage: the high-pressure hydrogen storage cylinder is burned as a whole, so that the fire source generated by the combustion device completely covers the high-pressure hydrogen storage cylinder, and a collection point is set outside the fire source. A radiation heat flux meter is set at the collection point to record the flame radiation flux; the fire source power in the overall burning stage is calculated according to the flame radiation flux and the area of ​​the fire source area generated by the combustion device; the fire source power at each target test point is obtained by the fire source power. m The overall fire radiation flux q w (t m );Record each target test point t m The overall fire radiation flux q w (t m ), and obtain the radiation flux distribution of the overall burning stage;

[0064] The fire source power in the local burning stage in step S101:

[0065]

[0066]

[0067] Among them, P l is the fire source power in the local fire stage, It is the flame radiation flux obtained by the thermal radiation flowmeter at the collection point during the local burning stage.

[0068] P w is the fire source power during the overall burning stage, is the flame radiation flux obtained by the thermal radiation flowmeter at the collection point during the overall burning stage. τ is the atmospheric transmittance; χ b is the fire source radiation fraction, which depends on the type of fuel, b The preferred range is: 0.15-0.25); F is the fire source viewing angle factor; It is the area of ​​the fire source area generated by the combustion device during the local fire stage. It is the area of ​​the fire source region generated by the combustion device during the overall burning stage;

[0069] It is the area of ​​the fire source area generated by the combustion device during the local fire stage, that is: A f It is the rectangular area formed by the gas pipelines carrying fuel in a group of combustion components located below the tail of the high-pressure hydrogen storage cylinder.

[0070] It is the area of ​​the fire source area generated by the combustion device during the overall burning stage, that is: A f It is the rectangular area formed by the gas pipelines carrying fuel in the two groups of combustion components of the combustion device.

[0071] When calculating the fire source power of the local burning stage and the fire source power of the overall burning stage by using general formulas (1) and (2) respectively, the average method can be adopted: for example, the heat radiation flowmeters from different collection points can be selected to calculate the flame radiation flux P by using general formula (1): l , the two P l The average value is taken to improve the accuracy of the fire source power in the local burning stage.

[0072] Target test point t m The local fire radiation flux q l (t m ) and the overall fire radiation flux q w (t m ) method:

[0073]

[0074]

[0075] Since the fire source viewing angle factor F is affected by the relative position of the external target point to be measured (including the acquisition point and the target test point) and the fire source, it is necessary to establish the coordinate values ​​in the coordinate system with the center of the fire source as the origin to obtain the fire source viewing angle factor F at different distances, including the following steps:

[0076] A. Determination of flame combustion surface: The plane where the fire source area of ​​the combustion device is located along the axial direction of the hydrogen storage cylinder is taken as the length direction of the fire source, and the plane along the radial direction of the hydrogen storage cylinder is taken as the width direction of the fire source; the direction perpendicular to the plane where the fire source area is located is taken as the height direction of the fire source; a rectangular model is established with the fire source length, fire source width and fire source height of the fire source area of ​​the combustion device as the length, width and height; the vertical plane where the width and height of the rectangular model are located is taken as the combustion surface: Figure 3 shown.

[0077] B. Coordinate system establishment: Establish a coordinate system according to the different positions of the external target points to be measured: For formulas (1) and (2), the external target points to be measured are the acquisition points; for formulas (3) and (4), the external target points to be measured are the target test points t m ;

[0078] When the external field target point 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;

[0079] When the external field target point to be measured is located in the axial direction of the hydrogen storage cylinder, the length direction of the fire source is taken as the X-axis, the width direction of the fire source is taken as the Y-axis, the height direction of the fire source is taken as the Z-axis, and the center of the burning surface is taken as the origin to establish a three-dimensional rectangular coordinate system; (such as Figure 3 shown);

[0080] C. Determination of fire source viewing angle factor F:

[0081]

[0082] Among them, x is the vertical distance between the external field target point to be measured and the combustion surface, y1, y2 are the intercepts of the combustion surface on the Y axis, and z1, z2 are the intercepts of the combustion surface on the Z axis.

[0083] S2. Obtain the jet fire heat release rate and jet fire length during the cylinder release stage: The high-pressure hydrogen storage cylinder is burned until the safety pressure relief device of the hydrogen storage cylinder is activated, so that the hydrogen storage cylinder releases jet fire; the jet fire heat release rate Q and jet fire length L are obtained through the release critical pressure of the hydrogen storage cylinder.f :

[0084] The heat release rate Q is:

[0085]

[0086] Where u is the hydrogen flow rate at the discharge nozzle, which is obtained by the following relationship:

[0087]

[0088] d is the discharge port diameter of the hydrogen storage cylinder, ΔH is the heat of hydrogen combustion, π is a constant, p0 is the maximum pressure value of the cylinder before discharge; γ is the adiabatic coefficient; R is the hydrogen gas constant; T is the hydrogen temperature at the discharge nozzle; b represents the control volume constant; K is the loss coefficient of hydrogen discharge; c p is the specific heat capacity of hydrogen at constant pressure; ΔT is the temperature drop during the hydrogen flow process;

[0089] Jet fire length L f for:

[0090]

[0091] Where, ρ is the hydrogen density at the discharge nozzle; ρ ∞ is the external air density; f s The ratio for complete combustion reaction of hydrogen;

[0092] S3, according to the heat release rate Q of the jet fire and the jet fire length L f , get each target test point t m The radiant flux distribution of the flame during the cylinder release phase includes the following steps:

[0093] S301, such as Figure 4 : In the jet fire length L f N flame point sources {p i}, i = 1, 2, ..., N, and make each flame point source evenly distributed; usually N ≥ 20.

[0094] S302, determine each flame point source p according to the heat release rate Q of the jet fire i At the target test point t m The incident radiation flux q of the jet flame at f (t m ):

[0095]

[0096] Among them, D i is the flame point source p i With the target test point t mThe distance between i represents the flame point source p i and the target test point t m is the angle between the line connecting the two planes and the horizontal plane; τ is the atmospheric transmittance; χ f is the jet fire radiation fraction, where χ f The preferred range is: 0.1-0.2); w i is the flame point source p i Weighted intensity 0.625% ≤ w i ≤9.375%; N is the total number of flame point sources; n is the number of heat source points before 0.75N;

[0097] S4. Obtain the total radiation flux at the target test point during the cylinder release phase: t m The radiation flux q during the overall burning phase w (t m ) and the jet flame incident radiation flux q f (t m ) to obtain the corresponding sum of each target test point t m The total radiation flux after the cylinder is released is q total (t m );

[0098] S5, according to the target test point t of the fire stage m The radiation flux at the target test point and the total radiation flux of the target test point after the gas cylinder is released are used to determine the hazardous area of ​​the target test point:

[0099] When l (t m )>4kW / m -2 When the target test point t m In the danger zone during the localized burn stage;

[0100] When l (t m )<1.6kW / m -2 When the target test point t m In the safe zone during the localized fire stage;

[0101] When w (t m )>4kW / m -2 When the target test point t m In the danger zone during the overall fire stage;

[0102] When w (t m )<1.6kW / m -2 When the target test point t m In the safe zone during the overall fire stage;

[0103] When total (t m )>4kW / m -2 When the target test point t m Being in the danger zone during the cylinder release phase;

[0104] When total (t m )<1.6kW / m -2 When the target test point t m Be in the safe zone during the cylinder release phase.

[0105] The following specific burning process of a gas cylinder is used to further describe the implementation of the invention. It should be noted that the implementation of the invention is not limited to this embodiment:

[0106] Taking 140L-35MPa 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.

[0107] Table 1 Specifications of high pressure hydrogen storage cylinders

[0108] Gas cylinder capacity Nominal pressure Cylinder length Gas cylinder diameter Discharge hole diameter 140L 35MPa 1755mm 385mm 5.7mm

[0109] S1. Carry out a fire test on the high-pressure hydrogen storage cylinder: The high-pressure hydrogen storage cylinder is burned by providing a fire source through a combustion device; firstly, the combustion device is arranged, the LPG cylinder is connected to the buffer tank 2 as the fuel supply end 1, the high-pressure hydrogen storage cylinder is fixed on the hydrogen storage cylinder fixed beam 9 through the hydrogen storage cylinder fixing clamp, and the head and tail of the high-pressure hydrogen storage cylinder are respectively located above the two groups of combustion components, that is, Figure 2 As shown, the head of the high-pressure hydrogen storage bottle is located in the front half area of ​​the combustion device, and the tail of the high-pressure hydrogen storage bottle is located in the rear half area of ​​the combustion device. The high-pressure hydrogen storage bottle is fixed on the hydrogen storage bottle fixed crossbeam 9 using a fixing device.

[0110] S101. Calculate the radiation flux at the target test point during the local burning stage: first start the combustion assembly in the second 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 wrapped by the flame. According to the parameters recorded by the radiation heat flow meter set around the combustion device, the fire source power during the local burning stage is calculated by general formula (1). When calculating, the average method can be used: that is, select the data of the heat radiation flow meter at two collection points close to the fire source, and calculate the flame radiation flux P l , the two P l The average value is taken to improve the accuracy of the fire source power in the local burning stage.

[0111] After obtaining the fire source power at the local burning stage, the power of each target test point t can be obtained according to the general formula (3): m The local fire radiation flux q l (t m ). The obtained q l (t m ) Save the records, and then get the target test points t from near to far from the fire source under the local fire state m The distribution of radiation flux.

[0112] S102, calculate the radiation flux at the target test point in the overall burning stage: start the combustion components of the front half of the combustion device, so that the combustion components of the front and rear parts of the combustion device are all in the starting state, and after the high-pressure hydrogen storage cylinder is changed from local burning to overall burning, the fire source power of the overall burning stage is calculated according to the parameters recorded by the radiation heat flux meter set around the combustion device through the general formula (1). After obtaining the fire source power of the overall burning stage, the fire source power of each target test point t can be obtained according to the general formula (4). m The local fire radiation flux q w (t m ). The obtained q w (t m ) Save the records, and then get the target test points t from near to far from the fire source under the overall fire state. m The distribution of radiation flux.

[0113] The method for determining the fire source viewing angle factor F in the general formulas (1), (2), (3) and (4) comprises the following steps:

[0114] A. Determination of flame combustion surface: For the combustion device in the present invention, if Figure 3 As shown: the rectangular long side of the burning device is used as the length direction of the fire source, and the rectangular short side of the burning device is used as the width direction of the fire source; the direction perpendicular to the upper surface of the burning device is used as the height direction of the fire source;

[0115] When a high-pressure hydrogen storage cylinder is partially burned, a rectangular parallelepiped model is established with the length of the gas pipeline in a group of combustion components as the length, the width corresponding to the number of gas pipelines with fuel in a group of combustion components below the tail of the high-pressure hydrogen storage cylinder as the width, and the height of the flame formed as the height;

[0116] When the high-pressure hydrogen storage cylinder is burned as a whole, the gas pipelines in the two groups of combustion components are partially or completely connected with fuel. Therefore, the total length of the gas pipelines in the two groups of combustion components is taken as the length, the width is taken as the width according to the number of gas pipelines connected with fuel in the combustion components, and the height of the flame is taken as the height to establish a rectangular parallelepiped model;

[0117] The vertical plane where the width and height of the rectangular model are located is the combustion surface:

[0118] B. Coordinate system establishment: 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;

[0119]

[0120] Where x is the vertical distance between the external target point to be measured and the burning surface. In formula (1), the external target point to be measured is the collection point set in the local burning stage, and in formula (2), the external target point to be measured is the collection point set in the overall burning stage. In formulas (3) and (4), the external target point to be measured is the collection point set in the overall burning stage. m ;.

[0121] y1, y2 are the intercepts of the burning surface on the Y axis (in fact, the coordinate values ​​of y1 and y2 are half of 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 burning surface on the Z axis. Similarly, z1 and z2 are half of the height of the fire source (z2 is a positive value, z1 is a negative value).

[0122] like Figure 5 As shown in the following figure: According to the requirements of the second phase of the global technical regulations for fuel cell electric vehicle safety, if the specific heat power of the local fire source is determined by the radiation heat flux meter parameters, 300kW / m -2 The burning area is 0.16m 2 , then the calculated radiation flux of the combustion device fire source in the external field reaches 4kW / m -2 The distance is 1.6-2.1m, reaching 1.6kW / m -2 The distance is 2.6-3.4m.

[0123] When the overall fire is turned into burning, if the overall fire source specific heat power is determined according to the radiation heat flux meter parameters 700kW / m -2 Around, the burning area is 0.85m 2 , then the radiation flux of the combustion device fire source in the external field reaches 4kW / m -2 The distance is 3.5-6.5m, reaching 1.6kW / m -2 The distance is 5.5-10.2m.

[0124] S2. Obtain the jet fire heat release rate and jet fire length during the cylinder release stage: When the high-pressure hydrogen storage cylinder is released, the jet flame formed will increase the external field radiation. The jet flame heat release rate and jet flame length are calculated based on parameters such as the cylinder release pressure. When calculating, the cylinder pressure before release is 1.2 times the nominal pressure as the benchmark. Taking a 140L-35MPa high-pressure hydrogen storage cylinder as an example, the maximum pressure before release is 42MPa.

[0125] According to the relationship between the discharge pressure of the gas cylinder and the hydrogen discharge flow rate, the hydrogen flow rate u at the discharge nozzle can be obtained:

[0126]

[0127] p0 is the maximum pressure value before the gas cylinder is released; γ is the adiabatic coefficient; R is the hydrogen gas constant; T is the hydrogen temperature at the release nozzle; b represents the control volume constant; K is the loss coefficient of hydrogen release; c p is the specific heat capacity of hydrogen at constant pressure; ΔT is the temperature drop during the hydrogen flow process;

[0128] According to the obtained discharge nozzle hydrogen flow rate u, the heat release rate Q can be obtained as:

[0129]

[0130] d is the diameter of the discharge port of the hydrogen storage cylinder, ΔH is the heat of combustion of hydrogen, and π=3.14 is a constant.

[0131] Jet fire length L f for:

[0132]

[0133] Among them, L f is the flame length, m; ρ is the hydrogen density at the discharge nozzle, kg / m 3 ρ ∞ is the external air density, kg / m 3 ;f s It is the ratio for complete combustion reaction of hydrogen.

[0134] S3, according to the heat release rate Q of the jet fire and the jet fire length L f , get each target test point t m The radiant flux distribution of the flame during the cylinder release phase includes the following steps:

[0135] S301, in the jet fire length L f In the range, 20 flame point sources {p1, p2..., p 20}, and make each flame point source evenly distributed. Among them, let p1 be at the bottom of the jet flame, p20 Located at the top of the jet flame. According to the position of each flame point source, the distance between each flame point source and the target test point t m The straight-line distance and the angle between the straight-line distance and the horizontal direction.

[0136] S302, determine each flame point source p according to the heat release rate Q of the jet fire i At the target test point t m The incident radiation flux q f (t m ):

[0137]

[0138] Among them, D i is the flame point source P k With the target test point t m The distance between i Represents each flame point source P k and the target test point t m is the angle between the line connecting the two and the horizontal direction; τ is the atmospheric transmittance; χ f is the jet fire radiation fraction; w i The weighted intensity of each flame point source 0.625% ≤ w i ≤9.375%; N is the total number of flame point sources; n is the number of heat source points before 0.75N;

[0139] S4, respectively, each target test point is t m The radiation flux q during the overall burning phase w (t m ) and the incident radiation flux q during the cylinder discharge phase f (t m ) to obtain the corresponding sum of each target test point t m The total radiation flux after the cylinder is released is q total (t m ),Right now:

[0140] q total (t m )=q w (t m )+q f (t m )

[0141] According to the results, q total (t m ) reaches 4kW / m 2 The distance is 11.5-14m, reaching 1.6kW / m 2 The distance is 21.6-25m.

[0142] S5, according to the target test point t of the fire stage m The radiation flux at the target test point and the total radiation flux of the target test point after the gas cylinder is released are used to determine the hazardous area of ​​the target test point:

[0143] When l (t m )>4kW / m -2 When the target test point t m In the danger zone during the localized burn stage;

[0144] When l (t m )<1.6kW / m -2 When the target test point t m In the safe zone during the localized fire stage;

[0145] When w (t m )>4kW / m -2 When the target test point t m In the danger zone during the overall fire stage;

[0146] When w (t m )<1.6kW / m -2 When the target test point t m In the safe zone during the overall fire stage;

[0147] When total (t m )>4kW / m -2 When the target test point t m Being in the danger zone during the cylinder release phase;

[0148] When total (t m )<1.6kW / m -2 When the target test point t m Be in the safe zone during the cylinder release phase.

[0149] The above contents are further detailed descriptions of the present invention in combination with specific preferred technical solutions, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for assessing the radiation hazard of flame release from a high-pressure hydrogen storage cylinder, characterized in that: The following steps are involved: S1. Carry out a fire test on the high-pressure hydrogen storage cylinder: Use a combustion device to provide a fire source to burn the high-pressure hydrogen storage cylinder; The following steps are involved: S101. Calculate the radiation flux at the target test point in the local burning stage: perform local burning on the high-pressure hydrogen storage cylinder, set a collection point outside the fire source, and set a radiation heat flux meter at the collection point to record the flame radiation flux; calculate the fire source power in the local burning stage according to the flame radiation flux and the area of ​​the fire source area generated by the combustion device; set multiple target test points {t m 1≤m≤M}, M is the number of target test points; each target test point t is obtained by the fire source power m The local fire radiation flux q l (t m );Record each of the target test points t m The local fire radiation flux q l (t m ), and obtain the radiation flux distribution in the local burning stage; S102, calculating the radiation flux at the target test point in the overall burning stage: the high-pressure hydrogen storage cylinder is burned as a whole, so that the fire source generated by the combustion device completely covers the high-pressure hydrogen storage cylinder, and a collection point is set outside the fire source, and a radiation heat flux meter is set at the collection point to record the flame radiation flux; the fire source power in the overall burning stage is calculated according to the flame radiation flux and the area of ​​the fire source area generated by the combustion device; the fire source power at each of the target test points is obtained by the fire source power. m The overall fire radiation flux q w (t m );Record each of the target test points t m The overall fire radiation flux q w (t m ), and obtain the radiation flux distribution of the overall burning stage; S2. Obtain the jet fire heat release rate and jet fire length during the cylinder release stage: The high-pressure hydrogen storage cylinder is burned until the safety pressure relief device of the hydrogen storage cylinder is activated, so that the hydrogen storage cylinder releases jet fire; the jet fire heat release rate Q and jet fire length L are obtained through the release critical pressure of the hydrogen storage cylinder. f : The heat release rate Q is: Where u is the hydrogen flow rate at the discharge nozzle, which is obtained by the following relationship: d is the discharge port diameter of the hydrogen storage cylinder, ΔH is the heat of hydrogen combustion, π is a constant, p0 is the maximum pressure value of the cylinder before discharge; γ is the adiabatic coefficient; R is the hydrogen gas constant; T is the hydrogen temperature at the discharge nozzle; b represents the control volume constant; K is the loss coefficient of hydrogen discharge; c p is the specific heat capacity of hydrogen at constant pressure; ΔT is the temperature drop during the hydrogen flow process; Jet fire length L f for: Where, ρ is the hydrogen density at the discharge nozzle; ρ ∞ is the external air density; f s The ratio for complete combustion reaction of hydrogen; S3, according to the jet fire heat release rate Q and jet fire length L f , get each target test point t m The jet fire radiation flux distribution during the cylinder release phase includes the following steps: S301, in the jet fire length L f N flame point sources {p i }, i=1, 2, ..., N, and each of the flame point sources is evenly distributed; S302, determine each flame point source p according to the heat release rate Q of the jet fire i At the target test point t m The incident radiation flux q of the jet flame at f (t m ): Among them, D i is the flame point source p i With the target test point t m The distance between i represents the flame point source p i and the target test point t m is the angle between the line connecting the two planes and the horizontal plane; τ is the atmospheric transmittance; χ f is the jet fire radiation fraction; w i is the flame point source p i Weighted intensity 0.625% ≤ w i ≤9.375%; N is the total number of flame point sources; n is the number of heat source points before 0.75N; S4. Obtain the total radiation flux at the target test point during the cylinder release phase: t m The radiation flux qw(tm) of the overall burning stage and the incident radiation flux q f (t m ) to obtain the corresponding sum of each target test point t m The total radiation flux after the cylinder is released is q total (t m ); S5. According to the radiation flux at the target test point during the fire phase and the total radiation flux at the target test point after the gas cylinder is released, the dangerous area of ​​the target test point is judged: When l (t m )>4kW / m -2 When the target test point t m In the danger zone during the localized fire stage; When l (t m )<1.6kW / m -2 When the target test point t m In the safe zone during the localized fire stage; When w (t m )>4kW / m -2 When the target test point t m In the danger zone during the overall fire stage; When w (t m )<1.6kW / m -2 When the target test point t m In the safe zone during the overall fire stage; When total (t m )>4kW / m -2 When the target test point t m Being in the danger zone during the cylinder release phase; When total (t m )<1.6kW / m -2 When the target test point t m In the safe zone during the cylinder release phase.

2. The method for evaluating the radiation hazard of the flame released from a high-pressure hydrogen storage cylinder according to claim 1 is characterized in that: In step S101, the fire source generated by the combustion device during local fire wraps around the tail of the high-pressure hydrogen storage cylinder.

3. The method for evaluating the radiation hazard of the flame released from the high-pressure hydrogen storage cylinder according to claim 1 is characterized in that: The fire source power in the local burning stage and the overall burning stage in step S1 is: Among them, P l is the fire source power in the local fire stage, is the flame radiation flux obtained by the thermal radiation flowmeter at the collection point during the local burning stage, P w is the fire source power during the overall burning stage, is the flame radiation flux obtained by the thermal radiation flowmeter at the collection point during the overall burning stage; τ is the atmospheric transmittance; χ b is the fire source radiation fraction; F is the fire source viewing angle factor; It is the area of ​​the fire source area generated by the combustion device during the local fire stage. It is the area of ​​the fire source zone generated by the combustion device during the overall burning stage.

4. The method for evaluating the radiation hazard of the flame released from the high-pressure hydrogen storage cylinder according to claim 3 is characterized in that: The target test point t m The local fire radiation flux q l (t m ) and the overall fire radiation flux q w (t m ) method:

5. The method for evaluating the radiation hazard of the flame released from the high-pressure hydrogen storage cylinder according to claim 3 or 4, characterized in that: The method for determining the fire source viewing angle factor F comprises the following steps: A. Determination of flame combustion surface: The plane where the fire source area of ​​the combustion device is located along the axial direction of the hydrogen storage cylinder is taken as the length direction of the fire source, and the plane along the radial direction of the hydrogen storage cylinder is taken as the width direction of the fire source; the direction perpendicular to the plane where the fire source area is located is taken as the height direction of the fire source; a rectangular parallelepiped model is established with the fire source length, fire source width and flame height formed in the fire source area of ​​the combustion device as the length, width and height; wherein, the plane where the width and height of the rectangular parallelepiped model are located is taken as the combustion surface: B. Establishment of coordinate system: Establish a coordinate system according to the different positions of the external field target points to be measured, wherein the external field target points to be measured include the acquisition points and the target test points: When the external field target point 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 burning surface as the origin; When the target point to be measured is located in the axial direction of the hydrogen storage cylinder, the length direction of the fire source is taken as the X-axis, the width direction of the fire source is taken as the Y-axis, the height direction of the fire source is taken as the Z-axis, and the center of the burning surface is taken as the origin to establish a three-dimensional rectangular coordinate system; C. Determine the fire source viewing angle factor F: Among them, x is the vertical distance between the external field target point to be measured and the combustion surface; y1, y2 are the intercepts of the combustion surface on the Y axis, and z1, z2 are the intercepts of the combustion surface on the Z axis.

6. The method for evaluating the radiation hazard of the flame released from a high-pressure hydrogen storage cylinder according to claim 1 is characterized in that: N≥20。 7. The combustion device used in the method for evaluating the radiation hazard of the released flame of the high-pressure hydrogen storage cylinder according to claim 1 is characterized in that: It comprises a rectangular bracket, on which two groups of combustion assemblies are fixed, and the two groups of combustion assemblies are symmetrically arranged; the combustion assembly comprises gas pipelines arranged in parallel with each other, and a mass flow controller connected to the gas pipeline; the gas pipeline is a pipe body with one end open and the other end closed, and the gas pipeline is provided with a plurality of gas nozzles connected to the gas pipeline; the open end of each gas pipeline is connected to the fuel supply end through a buffer tank through a mass flow controller; an ignition electrode is installed between the gas pipelines, and the ignition electrode is electrically connected to the ignition transformer; a hydrogen storage cylinder fixed beam is arranged above the rectangular bracket, the hydrogen storage cylinder fixed beam is arranged perpendicular to the layout direction of the gas pipeline, a fixed card slot is arranged on the hydrogen storage cylinder fixed beam, the hydrogen storage cylinder is fixedly arranged in the fixed card slot, and the high-pressure hydrogen storage cylinder is arranged parallel to the gas pipeline, and the head and tail of the high-pressure hydrogen storage cylinder are respectively located above the two groups of combustion assemblies; thermal radiation flow meters are respectively arranged at the long side and short side of the rectangular bracket, and the thermal radiation flow meters are respectively connected to the data collector through cooling water tanks.

8. The combustion device according to claim 7, characterized in that: The gas pipeline is arranged parallel to the long side of the rectangular bracket, the closed end of the gas pipeline is located in the middle of the rectangular bracket, and the hydrogen storage cylinder fixing beam is fixed to the middle of the rectangular bracket.

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