A numerical simulation method for release process of trifluorobromomethane extinguishing agent

Abstract

The application discloses a numerical simulation calculation method for a release process of trifluoro monobromomethane extinguishing agent, and belongs to the field of fire safety. Through AMESim simulation software, a one-dimensional simulation model covering gas storage, pipe network and spraying system is built by calling multiple professional libraries in a sketch mode, and the storage and transmission of the extinguishing agent are simulated in detail. In a submodel mode, reasonable mathematical models, such as two-phase flow models, are selected for elements, and relevant calculation models are determined. In a parameter mode, actual parameters of each element are set, including related parameters of the extinguishing agent and the environment. Finally, calculation is performed in a simulation mode, and indexes such as release time and nozzle pressure are obtained by analyzing the results, so that the functionality of the extinguishing system is evaluated, a basis is provided for system optimization, many problems of traditional simulation methods are solved, and the method has great significance for design and optimization of the extinguishing system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fire safety, and particularly relates to a numerical simulation calculation method for a release process of a trifluoro-monobromomethane extinguishing agent. BACKGROUND

[0002] Trifluoro-monobromomethane has many advantages such as high extinguishing efficiency, low toxicity, long shelf life, etc., and is widely used in the military field. For the release process of a ship extinguishing system, water calculation can be carried out by using the requirements and methods in the relevant standard specifications, or the method of simulation experiment can be used for verification. However, large-scale pipe network experiments are costly, and the measured data are limited by the types, positions, quantities and accuracy of sensors; water calculation cannot obtain the details of the two-phase flow of the extinguishing agent at each place in the pipe network. At present, numerical simulation calculation of the release process of the extinguishing agent of the extinguishing system is mostly one-way flow or three-dimensional simulation, the former has low calculation accuracy, the latter has high calculation cost and long calculation period, and the numerical simulation calculation of one-dimensional simulation of multiphase flow is rarely mentioned.

[0003] Simcenter Amesim is a multi-disciplinary complex system modeling and simulation platform. The platform contains typical model libraries such as pneumatic, hydraulic, control system, thermal calculation, multiphase flow, etc. By calling related components in each model library, a numerical simulation calculation model can be built to simulate and study actual engineering scientific problems. The present application uses the modeling idea of the simulation platform and the visual user interface, through the combination of each module and the input of related parameters, a gas extinguishing system pipe network flow model can be directly constructed to study the release of trifluoro-monobromomethane extinguishing agent from the gas cylinder, the flow in the pipe system and the spraying process, and then the release time of the extinguishing agent of the extinguishing system, the pressure at the nozzle, the phase change process of the extinguishing agent and other evaluation indexes are obtained, so as to judge the rationality of the design of the extinguishing system and provide guidance for the optimization of the extinguishing system. SUMMARY

[0004] In view of the above technical problems, the present application provides a numerical simulation calculation method for a release process of a trifluoro-monobromomethane extinguishing agent, comprising the following steps:

[0005] Step S1: creating a system and building a basic model in a sketch mode of a professional simulation software.

[0006] Step S2: selecting a reasonable mathematical model for system elements in a submodel mode of the professional simulation software.

[0007] Step S3: setting required parameters for each module element in a parameter mode of the professional simulation software.

[0008] Step S4: performing numerical simulation calculation on the release process of the new extinguishing agent in a simulation mode of the professional simulation software and analyzing the simulation calculation results.

[0009] Further, the step S1 system building step includes, step S101: by means of the first function library, the second function library, the third function library, the fourth function library, the fifth function library and the sixth function library complete the building of new fire extinguishing agent fire extinguishing gas storage system model.

[0010] Step S102: by calling the second function library, the fifth function library and the sixth function library complete the building of new fire extinguishing agent fire extinguishing pipe network system model. The pipe network system model element is composed of the first heat exchange pipe, the first heat capacity element and the first control element with special resistance and capacitance characteristics. The first heat exchange pipe can handle complex flow, phase change and heat exchange working condition, accurately calculate the pressure and density state parameter, so as to accurately obtain the pressure loss of multiphase or single phase. The first heat capacity element is used to accurately calculate the heat exchange between the pipeline and the fire extinguishing agent and the environment. At the same time, considering the special structure in the pipe network system, the influence of the special structure on the flow of fire extinguishing agent is simulated by combining the special elements.

[0011] Step S103: by calling the second function library, the fifth function library and the sixth function library complete the building of new fire extinguishing agent fire extinguishing spray system model.

[0012] Further, in the gas storage system model, the gas cylinder is mainly composed of five elements, i.e. the first element, the second element, the third element, the fourth element and the fifth element; the first element is used as a container for storing a certain driving gas, simulating the storage condition of the driving gas; the second element is used as a pneumatic driving structure to push the driving gas to move; the fifth element is used as a storage container for the new fire extinguishing agent, responsible for storing the fire extinguishing agent; the fourth element is used as a driving structure for the spray of the fire extinguishing agent, controlling the spray of the fire extinguishing agent; the third element is used as an element for simulating the special interface in the liquid storage bottle, which has a key role in the model although its mass is small. By reasonably setting its parameters, such as setting the mass to be extremely small, and setting its activity height according to the actual situation to reflect the storage height of the fire extinguishing agent in the gas cylinder, and setting specific parameters to simulate the accelerated release process after the driving gas is sprayed, the release speed change of the fire extinguishing agent is accurately simulated.

[0013] Further, the step S2 of selecting mathematical model includes, step S201: due to the special physical change in the release process of the new fire extinguishing agent, a special multiphase flow calculation model is selected for the numerical simulation calculation model, which needs to fully consider the actual flow speed of different phase states and the friction between each phase state and the pipe wall surface and the mutual friction between phase states.

[0014] Step S202: the numerical simulation calculation model pipe system selects an appropriate friction factor calculation model. This model can accurately calculate the friction coefficient according to the specific surface characteristics of the pipeline, the flow characteristics and physical property factors of the fluid, so as to accurately calculate the pressure loss in the pipeline.

[0015] Step S203: Numerical simulation calculation model nozzle resistance coefficient is obtained by combining the calculation model and professional simulation software according to a large number of test measured resistance coefficient relationship.

[0016] Further, the step S3 of setting the element parameters comprises: step 301: according to the characteristics and filling conditions of the fire extinguishing agent in the actual system design, the parameter setting of the fire extinguishing agent storage system is completed; the first element and the fifth element are input as the volume of the driving gas and the new fire extinguishing agent in the gas storage system.

[0017] Step 302: according to the arrangement, properties and nozzle model of the fire extinguishing system pipe network, the parameter setting of the fire extinguishing agent pipe network system is completed.

[0018] Step S303: according to the actual environmental characteristics, the setting of the simulation system environmental parameters is completed.

[0019] Further, the step S4 of simulation calculation comprises: step S401: according to the actual situation, the simulation time and step length are set in the simulation calculation setting.

[0020] Step S402: numerical simulation calculation is carried out, and the simulation results are extracted; in the calculation process, the model will calculate the state parameters of the fire extinguishing agent at each time and each position according to the set parameters and mathematical model, including pressure, temperature, velocity and special phase ratio.

[0021] Step S403: analyze the simulation results, extract the fire extinguishing agent release time, fire extinguishing agent nozzle pressure, pipe special phase ratio change data, and perform functional evaluation on the new fire extinguishing agent fire extinguishing system.

[0022] Further, the first function library, the second function library, the third function library, the fourth function library, the fifth function library and the sixth function library are called to complete the construction of the new fire extinguishing agent fire extinguishing gas storage system model; the first function library provides basic function elements and models related to storage and driving, which are used to simulate the basic characteristics in the process of fire extinguishing agent storage and driving; the second function library is used for simulation of special flow phenomena, which can accurately process the interaction and change of special phases; the third function library is used for simulation related to driving gas; the fourth function library provides elements for simulating special structures; the fifth function library is used for simulation of control signals and calculation related to special flow characteristics; the sixth function library is used for processing heat exchange related calculation, reflecting various state changes of the new fire extinguishing agent in the gas storage system.

[0023] Further, an simulation model is established, parameter setting is completed, and simulation calculation is carried out; from the simulation result, the release time of extinguishing agent of the extinguishing system, the pressure at the nozzle, and the functional evaluation index of the special phase proportion extinguishing system are directly read out, and then the extinguishing system is functionally evaluated; by comparing and analyzing these indexes with the design requirements, whether the extinguishing system meets the requirements in terms of the release speed of extinguishing agent, the spraying effect and the system stability is judged; if the release time of extinguishing agent does not meet the requirements, the part related to the storage and release of extinguishing agent in the model needs to be checked; if the pressure at the nozzle does not meet the requirements, the nozzle configuration and related parameters and the driving pressure setting need to be reviewed; if the special phase proportion in the pipeline changes abnormally, the pipeline system design and the extinguishing agent characteristics are considered.

[0024] The present application has the beneficial effects compared with the prior art: the present application is suitable for numerical simulation research and functional verification of trifluoro-monobromomethane extinguishing system. By building a model according to the actual design scheme, selecting a mathematical model, setting parameters according to working conditions, simulating calculation and result analysis, comparing with full-scale experiment verification model accuracy, effectively evaluating the function of the extinguishing system and putting forward optimization suggestions. The present application solves the problems of low precision, long time consumption and difficult parameter adjustment of traditional numerical simulation method, effectively supports the optimization of extinguishing system, and has great significance for the design and optimization of extinguishing system. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The overall flowchart of simulation calculation of the present application is shown.

[0026] Figure 2 The schematic flowchart of model building of the present application is shown.

[0027] Figure 3 The exemplary step flowchart of selecting mathematical model of the present application is shown.

[0028] Figure 4 The exemplary step flowchart of setting parameters of the present application is shown.

[0029] Figure 5 The exemplary step flowchart of simulation calculation of the present application is shown. DETAILED DESCRIPTION

[0030] Embodiment: As the present embodiment is based on AMESim simulation platform, a set of one-dimensional two-phase flow numerical simulation calculation method of trifluoro-monobromomethane extinguishing agent release process is developed as shown in Figure 1 , including the following steps:

[0031] Step S1: create a system and build a basic model in the sketch mode of professional simulation software.

[0032] Step S2: select a reasonable mathematical model for system elements in the submodel mode of professional simulation software.

[0033] Step S3: Set the required parameters for each module element in the professional simulation software parameter mode.

[0034] Step S4: Numerical simulation calculation and analysis of simulation calculation results of new extinguishing agent release process in professional simulation software simulation mode.

[0035] As Figure 2 shown, the steps of creating a system and building a basic model for this embodiment include,

[0036] Step S101: Build a new extinguishing agent fire extinguishing gas storage system model by means of the first, second, third, fourth, fifth and sixth function libraries.

[0037] Step S102: Build a new extinguishing agent fire extinguishing pipe network system model by calling the second, fifth and sixth function libraries. The pipe network system model elements are composed of a first heat exchange pipe, a first heat capacity element and a first control element with special resistance and capacitance characteristics. The first heat exchange pipe can handle complex flow, phase change and heat exchange conditions, accurately calculate pressure and density state parameters, and thus accurately obtain the pressure loss of multiple phases or single phase. The first heat capacity element is used to accurately calculate the heat exchange between the pipe and the extinguishing agent and the environment, and at the same time, considering the inevitable special structure in the pipe network system, the influence of the special structure on the flow of the extinguishing agent is simulated by combining specific elements.

[0038] Step S103: Build a new extinguishing agent fire extinguishing spray system model by calling the second, fifth and sixth function libraries.

[0039] In the gas storage system model, the gas storage cylinder is mainly composed of five elements, i.e., a first element, a second element, a third element, a fourth element and a fifth element. The first element is a container for storing a certain driving gas, simulating the storage condition of the driving gas. The second element is a pneumatic driving structure that drives the driving gas to move. The fifth element is a storage container for the new extinguishing agent, responsible for storing the extinguishing agent. The fourth element is a driving structure for the extinguishing agent to spray out, controlling the spraying out of the extinguishing agent. The third element is an element simulating the special interface in the liquid storage bottle, which has a key role in the model although its mass is small. By reasonably setting its parameters, such as setting the mass to be extremely small, and setting its activity height according to the actual situation to reflect the storage height of the extinguishing agent in the gas storage cylinder, and setting specific parameters to simulate the accelerated release process of the driving gas in the later stage of spraying, the release speed change of the extinguishing agent is accurately simulated.

[0040] As Figure 3The following are exemplary steps for selecting a reasonable mathematical model in this embodiment, including step S201: Since the release process of the new fire extinguishing agent is accompanied by special physical changes, the numerical simulation calculation model uses a special multiphase flow calculation model, which needs to fully consider the actual proportion of special phases and the actual flow velocity of different phases, as well as the friction between each phase and the pipe wall and the mutual friction between phases.

[0041] Step S202: Numerical simulation calculation model of pipeline system. Select the appropriate friction factor calculation model. This model can accurately calculate the friction coefficient based on the specific surface characteristics of the pipeline, the flow characteristics of the fluid and physical properties, so as to accurately calculate the pressure loss in the pipeline.

[0042] Step S203: The nozzle resistance coefficient of the numerical simulation model is calculated by combining the calculation model and professional simulation software based on the resistance coefficient relationship obtained from a large number of experiments.

[0043] like Figure 4 The diagram illustrates exemplary steps for setting parameters in this embodiment, including:

[0044] Step 301: Based on the characteristics and filling conditions of the extinguishing agent in the actual system design, complete the parameter settings of the extinguishing agent storage system; the inputs of the first and fifth elements are the volumes of the driving gas and the new extinguishing agent in the gas storage system.

[0045] Step 302: Based on the layout, properties and nozzle models of the fire extinguishing system piping network, complete the parameter settings for the fire extinguishing agent piping network system.

[0046] Step S303: Set the simulation system environment parameters according to the actual environmental characteristics.

[0047] like Figure 5 The diagram illustrates exemplary steps for simulation calculations in this embodiment, including:

[0048] Step S401: Set the simulation duration and step size in the simulation calculation settings according to the actual situation.

[0049] Step S402: Perform numerical simulation calculations and extract simulation results: During the calculation process, the model will calculate the state parameters of the extinguishing agent at various times and locations based on the set parameters and mathematical model, including pressure, temperature, velocity, and proportion of special phases.

[0050] Step S403: Analyze the simulation results, extract data on extinguishing agent release time, extinguishing agent nozzle pressure, and changes in the proportion of special phases in the pipeline, and conduct a functional evaluation of the new extinguishing agent fire extinguishing system.

[0051] The first function library, the second function library, the third function library, the fourth function library, the fifth function library and the sixth function library are called to complete the building of the new fire extinguishing agent fire extinguishing gas storage system model; the first function library provides basic function elements and models related to storage and driving, and is used for simulating the basic characteristics in the process of fire extinguishing agent storage and driving; the second function library is used for simulating special flow phenomena, and can accurately process the interaction and change of special phases; the third function library is used for simulating the part related to driving gas; the fourth function library provides elements for simulating special structures; the fifth function library is used for simulating control signals and calculating special flow characteristics; and the sixth function library is used for processing heat exchange related calculation, reflecting various state changes of the new fire extinguishing agent in the gas storage system.

[0052] The simulation model is established, parameter setting is completed, and simulation calculation is carried out; from the simulation results, the fire extinguishing agent release time, the pressure at the nozzle and the special phase proportion of the fire extinguishing system are directly read out as functional evaluation indexes of the fire extinguishing system, and then the fire extinguishing system is functionally evaluated; by comparing and analyzing these indexes with design requirements, whether the fire extinguishing system meets the requirements in terms of fire extinguishing agent release speed, spraying effect and system stability is judged; if the fire extinguishing agent release time does not meet the requirements, the part related to fire extinguishing agent storage and release in the model needs to be checked; if the pressure at the nozzle does not meet the requirements, the nozzle configuration and related parameters and driving pressure setting need to be reviewed; and if the special phase proportion in the pipeline changes abnormally, the pipeline system design and fire extinguishing agent characteristics need to be considered.

[0053] The above content is only an example and description of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as the modifications or supplements do not deviate from the invention or exceed the scope defined by the present claims, and should belong to the protection scope of the present application.

Claims

1. A numerical simulation method of a release process of a trifluorobromomethane extinguishing agent, characterized by, The method comprises the following steps: Step S1: creating a system and building a basic model in a sketch mode of professional simulation software; Step S2: selecting reasonable mathematical models for system elements in a submodel mode of the professional simulation software; Step S3: setting required parameters for each module element in a parameter mode of the professional simulation software; Step S4: performing numerical simulation calculation on the release process of the new fire extinguishing agent in a simulation mode of the professional simulation software and analyzing simulation calculation results; The step of system building comprises: Step S101: building a new fire extinguishing agent fire extinguishing gas storage system model by means of the first function library, the second function library, the third function library, the fourth function library, the fifth function library and the sixth function library; Step S102: building a new fire extinguishing agent fire extinguishing pipe network system model by calling the second function library, the fifth function library and the sixth function library; the pipe network system model element is composed of a first heat exchange pipe, a first heat capacity element and a first control element, the first heat exchange pipe can process complex flow, phase change and heat exchange working conditions, accurately calculate pressure and density state parameters, and thus accurately obtain pressure loss of multiple phases or single phase, the first heat capacity element is used for accurately calculating heat exchange between the pipe and the fire extinguishing agent and the environment, and the special structure in the pipe network system is inevitable, and the influence of the special structure on the flow of the fire extinguishing agent is simulated by combining specific elements; Step S103: building a new fire extinguishing agent fire extinguishing spraying system model by calling the second function library, the fifth function library and the sixth function library; In the gas storage system model, the gas storage cylinder is mainly composed of five elements, i.e., a first element, a second element, a third element, a fourth element and a fifth element; the first element is used as a container for storing a certain driving gas, simulating the storage state of the driving gas; the second element is used as a pneumatic driving structure to drive the driving gas to move; The fifth element is used as a storage container for the new fire extinguishing agent and is responsible for storing the fire extinguishing agent; the fourth element is used as a driving structure for spraying the fire extinguishing agent and controls the spraying of the fire extinguishing agent; the third element is used as an element for simulating a special interface in the liquid storage cylinder, has a key role in the model although its mass is small, its parameters are reasonably set, the mass is set to be extremely small, and the activity height is set according to the actual situation to reflect the storage height of the fire extinguishing agent in the gas storage cylinder, and specific parameters are set to simulate the accelerated release process of the driving gas in the late spraying stage, so as to accurately simulate the change of the release speed of the fire extinguishing agent; The building of the new fire extinguishing agent fire extinguishing gas storage system model is completed by calling the first function library, the second function library, the third function library, the fourth function library, the fifth function library and the sixth function library; the first function library provides basic function elements and models related to storage and driving, and is used for simulating the basic characteristics in the process of fire extinguishing agent storage and driving; the second function library is used for simulating special flow phenomena, and can accurately process the interaction and change of special phases; the third function library is used for simulating the part related to the driving gas; the fourth function library provides elements for simulating special structures; the fifth function library is used for simulating control signals and calculating special flow characteristics; and the sixth function library is used for processing heat exchange related calculations, reflecting various state changes of the new fire extinguishing agent in the gas storage system.

2. The numerical simulation method for the release process of a trifluorobromomethane extinguishing agent according to claim 1, characterized in that: The step S2 of selecting a mathematical model comprises: Step S201: Since the release process of the new fire extinguishing agent is accompanied by special physical changes, a special multiphase flow calculation model is selected for the numerical simulation calculation model, and the actual flow speed of the real special phase ratio and different phases, as well as the friction between the phase and the pipe wall and the mutual friction between the phases, are comprehensively considered; Step S202: The numerical simulation calculation model pipeline system selects an appropriate friction factor calculation model, which accurately calculates the friction coefficient according to the specific surface characteristics of the pipeline, the flow characteristics and physical property factors of the fluid, so as to accurately calculate the pressure loss in the pipeline; Step S203: The nozzle resistance coefficient of the numerical simulation calculation model is calculated by combining the calculation model and the professional simulation software according to the resistance coefficient relationship measured by the test.

3. The numerical simulation method for the release process of a CF3Br fire extinguishing agent according to claim 1, characterized in that: The step S3 of setting element parameters comprises: Step 301: According to the characteristics and filling conditions of the fire extinguishing agent in the actual system design, the parameter setting of the fire extinguishing agent storage system is completed; the first element and the fifth element are input as the volume of the driving gas and the new fire extinguishing agent in the gas storage system; Step 302: According to the arrangement, properties and nozzle model of the fire extinguishing system pipeline network, the parameter setting of the fire extinguishing agent pipeline network system is completed; Step S303: According to the actual environmental characteristics, the simulation system environmental parameter setting is completed.

4. The numerical simulation method for the release process of a CF3Br fire extinguishing agent according to claim 1, characterized in that: The step S4 of simulation calculation comprises: Step S401: According to the actual situation, the simulation time and step length are set in the simulation calculation setting; Step S402: Numerical simulation calculation is carried out, and the simulation results are extracted; in the calculation process, the model will calculate the state parameters of the fire extinguishing agent at each time and each position according to the set parameters and mathematical model, including pressure, temperature, speed and special phase ratio; Step S403: The simulation results are analyzed, and the fire extinguishing agent release time, fire extinguishing agent nozzle pressure and special phase ratio change data in the pipeline are extracted, and the functionality of the new fire extinguishing agent fire extinguishing system is evaluated.

5. The numerical simulation method for the release process of a trifluorobromomethane extinguishing agent according to claim 1, characterized in that: The simulation model is established, the parameter setting is completed, and the simulation calculation is performed; from the simulation result, the extinguishing agent release time, the nozzle pressure, and the special phase proportion functional evaluation indexes of the extinguishing system are directly read out, and then the extinguishing system is functionally evaluated; by comparing and analyzing these indexes with the design requirements, whether the extinguishing agent release speed, the spraying effect, and the system stability of the extinguishing system meet the requirements is judged; if the extinguishing agent release time does not meet the requirements, the part related to the extinguishing agent storage and release in the model needs to be checked; if the nozzle pressure does not meet the requirements, the nozzle configuration and related parameters and the driving pressure setting need to be reviewed; if the special phase proportion in the pipeline changes abnormally, the pipeline system design and the extinguishing agent characteristics are considered.

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