Preparation method of cable insulation material for simulating fire short-time over-temperature

Abstract

The invention discloses a preparation method of a cable insulation material for simulating fire short-time over-temperature. The method comprises the steps that 1, a multi-physics-field coupled cable tunnel fire simulation model is established according to a real cable tunnel, the cable tunnel fire simulation model comprises a cable support, and target cables are placed on the specific layer number of the cable support; 2, performing a fire simulation test on the target cable, and drawing a simulation temperature curve fm (t) of the target cable by using the cable tunnel fire simulation model; 3, building an over-temperature test platform by imitating the cable tunnel fire simulation model; 4, setting an over-temperature test temperature curve for the high-temperature processing equipment of the over-temperature test platform, wherein the error between the over-temperature test temperature curve and the simulation temperature curve fm (t) is within a preset error range; and 5, according to the over-temperature test temperature curve, carrying out an over-temperature test on the sample cable insulation material to obtain the cable insulation material which is over-heated in a short time in a fire disaster. The technical problem that the over-temperature cable insulating material conforming to the actual fire situation cannot be accurately prepared is solved.

Description

Technical Field

[0001] The invention relates to the technical field of cable tunnel disaster protection, and in particular to a method for preparing a cable insulation material for simulating short-term overheating in a fire. Background Art

[0002] In response to the above problems, based on the actual causes and development of high-voltage cable fires, considering that high-voltage cable tunnels are mainly ignited by high-temperature fault arcs caused by breakdown of intermediate joints, we have developed a fire source device that simulates an equivalent fire, simulated the tunnel environment layout, and conducted fire resistance tests on fire protection products. This can more effectively obtain the effective protection time of fire protection products and determine whether the fire protection products meet the protection requirements. Summary of the invention

[0003] To solve the above problems, an embodiment of the present invention provides a method for preparing cable insulation materials that simulate short-term overheating in fire, so as to at least solve the technical problem that it is impossible to accurately prepare overheated cable insulation materials that match actual fire conditions.

[0004] According to one aspect of an embodiment of the present invention, there is provided a method for preparing a cable insulation material for simulating short-term overheating in a fire, comprising:

[0005] Step 1: A cable tunnel fire simulation model with multi-physics field coupling is established according to a real cable tunnel. The structure of the cable tunnel fire simulation model includes tunnel lining and cable racks for laying cables. Fire-resistant and heat-insulating fire partitions are set at specific layers of the cable racks and target cables are placed.

[0006] Step 2: Conduct a fire simulation test on the target cable, record the heating time and cooling time of the fire simulation test, and use the cable tunnel fire simulation model to draw the simulated temperature curve f of the insulation layer of the target cable. m (t), wherein the heating time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed to trigger, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame. The cooling time of the fire simulation test is the time when the temperature of the insulation layer of the target cable drops to the preset temperature;

[0007] Step 3: Build an over-temperature test platform based on the cable tunnel fire simulation model, where the over-temperature test platform includes high-temperature processing equipment, vacuum equipment, inert gas generator and air compressor;

[0008] Step 4: Set up and simulate the temperature curve f for the high temperature processing equipment of the overtemperature test platform m (t) Over-temperature test temperature curve with error within the predetermined error range;

[0009] Step 5: According to the over-temperature test temperature curve, an over-temperature test is performed on the sample cable insulation material to obtain the cable insulation material that is overheated for a short time in fire.

[0010] Optionally, in step 1: a cable tunnel fire simulation model coupled with multi-physics fields is established according to a real cable tunnel, the structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables, and fire-resistant and heat-insulating fire partitions are set at specific layers of the cable support and target cables are placed, including the following steps:

[0011] Step 1.1: A cable tunnel fire simulation model is established based on a real cable tunnel, wherein the tunnel lining of the cable tunnel fire simulation model is concrete, the outside of the tunnel lining is soil, and both sides of the cable tunnel fire simulation model include multi-layer brackets, on which cables of different voltage levels, different radii and the same length are arranged respectively;

[0012] Step 1.2: Select a specific number of layers in the multi-layer support, arrange fire-resistant and heat-insulating fireproof partitions below and on the sides of the specific number of layers to surround the target cables placed on the specific number of layers, and place the target cables;

[0013] Step 1.3: According to the temperature, environmental pressure and ventilation conditions of a real cable tunnel, the temperature and environmental pressure are set for the cable tunnel fire simulation model, and the laminar inlet and outlet are set at the head and end of the cable tunnel fire simulation model;

[0014] Step 1.4: Select a predetermined fire source layer in the multi-layer support and set a fire source in the predetermined fire source layer.

[0015] Optionally, in step 2, a fire simulation test is performed on the target cable, the heating time and cooling time of the fire simulation test are recorded, and a simulated temperature curve f of the insulation layer of the target cable is drawn using the cable tunnel fire simulation model. m (t), comprising the following steps:

[0016] Step 2.1: Set the fire source power curve according to the real cable tunnel and set the laminar inlet normal inflow velocity u i Or velocity field u i (x,y,z), start the fire simulation test;

[0017] Step 2.2: Record the temperature rise time of the fire simulation test, where the temperature rise time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed to be triggered, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame;

[0018] Step 2.3: Record the cooling time of the fire simulation test, wherein the cooling time of the fire simulation test is the time it takes for the temperature of the insulation layer of the target cable to drop to a preset temperature after the fire extinguishing bomb is finished extinguishing the fire;

[0019] Step 2.4: Use the cable tunnel fire simulation model to draw the simulated temperature curve f of the target cable insulation layer m (t).

[0020] Optionally, in step 3, an over-temperature test platform is constructed according to a cable tunnel fire simulation model, including the following steps:

[0021] Step 3.1: The high temperature treatment equipment uses a heating box with automatic temperature control function. The heating box is equipped with temperature sensors, heating elements, gas input and output channels, and an adjustable temperature control program. The temperature control program is used to accurately adjust the power of the heating element in a short time to fully reflect the rapid rise and fall of the actual fire temperature;

[0022] Step 3.2: The vacuum pump is used as a vacuum pump, wherein the vacuum pump is used to make the heating box into a vacuum state before heating the sample cable;

[0023] Step 3.3: The inert gas generator uses a nitrogen generator, which is used to supply low-temperature or normal-temperature nitrogen with different volume flow rates to the heating box. By adjusting the size of the flow valve of the heating box, the size of the flow valve of the nitrogen generator, and the pressure gear of the air compressor, the error between the cooling rate of the heating box and the cooling rate of the simulated temperature curve is kept within a predetermined error range.

[0024] Optionally, in step 4, a temperature curve f is set for the high temperature processing equipment of the over-temperature test platform. m The over-temperature test temperature curve of the error of (t) is within the predetermined error range, comprising the following steps:

[0025] Step 4.1: Simulate the temperature curve f of the insulation layer of the target cable m (t) selects n temperature points as the n temperature points of the heating box, and draws a point-line graph as the preset temperature curve g of the heating box m (t);

[0026] Step 4.2: Set the preset temperature curve g of the heating box m (t) and simulation temperature curve f m (t) to compare and determine the preset temperature curve g m (t) The time period corresponding to each two temperature points and the simulated temperature curve f m (t) The error between the time periods corresponding to the same two temperature points. If in the time period [t k ,tk+1 ] There is a little bit of memory x The absolute value of the relative error is greater than the predetermined error value E a Then the time period [t k ,t k+1 ] is divided into two periods, and the time period [t k ,t k+1 The temperature point corresponding to the center point of ] is taken as the new temperature point, and the above steps are repeated until the error values ​​of all time periods are less than the predetermined error value E a , generating an updated temperature curve of the heating box;

[0027] Step 4.3: Connect the power supply of each device of the temperature test platform, use a vacuum pump to evacuate the heating box to a vacuum state, start the heating box, and start heating and cooling the heating box according to the updated temperature curve, and draw the actual temperature curve h(t) of the heating box;

[0028] Step 4.4: Compare the actual temperature curve h(t) with the simulated temperature curve f m (t) to determine the actual temperature curve h(t) and the simulated temperature curve f m (t), if at time point t y The error value is greater than the predetermined error value E b , adjust the heating program, cooling program, flow valve of the heating box or flow valve of the nitrogen generator to reduce the time point t y Repeat step 4.4 until the actual temperature curve h(t) is consistent with the simulated temperature curve f m (t) The error value at each time point is less than the predetermined error value E b , and obtain the over-temperature test temperature curve.

[0029] Optionally, in step 5, an over-temperature test is performed on a sample cable according to an over-temperature test temperature curve to obtain a cable insulation material that is over-heated for a short time in a fire, including the following steps:

[0030] Step 5.1: Set the temperature control program of the heating box according to the over-temperature test temperature curve, wherein, within a predetermined time period before the heating box is heated up, start the air compressor and the nitrogen generator in advance to prepare nitrogen, and when the nitrogen pressure in the nitrogen generator reaches a predetermined pressure value, turn off the air compressor and the nitrogen generator, and wait for the heating box to be heated up. After the heating box is heated up, immediately open the air inlet valve of the heating box and the nitrogen generator to deliver nitrogen to the heating box at a constant speed, and when the gas in the heating box returns to atmospheric pressure, open the pressure regulating valve of the heating box, and at the same time turn on the air compressor to maintain the nitrogen pressure in the nitrogen generator;

[0031] Step 5.2: Perform an over-temperature test on the sample cable placed in the heating box, wherein when preparing the sample cable, use a cable slicer to cut the cable insulation layer into a suitable shape according to a predetermined thickness, and rinse and dry the sample cable;

[0032] Step 5.3: After the temperature control program of the heating box is completed, close the air inlet valve of the heating box, the pressure regulating valve of the heating box, the nitrogen generator and the air compressor, open the box door, take out the sample cable that has passed the temperature test and seal it to obtain the cable insulation material that is short-term overheated in fire.

[0033] According to another aspect of an embodiment of the present invention, there is provided a device for preparing a cable insulation material for simulating short-term overheating in a fire, comprising:

[0034] Establishing a module for establishing a cable tunnel fire simulation model with multi-physics field coupling according to a real cable tunnel. The structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables. Fire-resistant and heat-insulating fire partitions are set at specific layers of the cable support and target cables are placed.

[0035] The simulation test module is used to perform a fire simulation test on the target cable, record the heating time and cooling time of the fire simulation test, and use the cable tunnel fire simulation model to draw the simulation temperature curve of the insulation layer of the target cable. m (t), wherein the heating time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time of delayed triggering of the fire extinguishing bomb, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame. The cooling time of the fire simulation test is the time when the temperature of the insulation layer of the target cable drops to the preset temperature;

[0036] An over-temperature test platform building module is used to build an over-temperature test platform based on the cable tunnel fire simulation model. The over-temperature test platform includes high-temperature processing equipment, vacuum equipment, inert gas generator and air compressor;

[0037] The setting module is used to set and simulate the temperature curve f for the high temperature processing equipment of the over-temperature test platform m (t) Over-temperature test temperature curve with error within the predetermined error range;

[0038] The over-temperature test module is used to perform an over-temperature test on the sample cable according to the over-temperature test temperature curve to obtain the cable insulation material that is overheated for a short time in fire.

[0039] According to another aspect of an embodiment of the present invention, a non-volatile storage medium is provided, which stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor and executing any one of a method for preparing cable insulation materials that simulates short-term overheating in a fire.

[0040] According to another aspect of an embodiment of the present invention, there is provided an electronic device, comprising: one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement any one of the methods for preparing cable insulation materials that simulates short-term overheating in fire.

[0041] According to another aspect of an embodiment of the present invention, there is also provided a computer program product, including a computer program, which, when executed by a processor, implements any one of the above-mentioned methods for preparing cable insulation materials that simulates short-term overheating in fire.

[0042] The present invention provides a method for preparing a cable insulation material for simulating short-term overheating in fire, and the advantages of the present invention are:

[0043] (1) Compared with the general high-temperature aging treatment method for cable insulation materials with fixed temperature rise and temperature, the present application fully considers the fire extinguishing trigger time when the current fire extinguishing device is fully deployed, and accordingly calculates the heating and cooling process of the cable insulation layer in the subsequent process and accurately simulates the entire process of short-term overheating of the cable in the event of a fire in an actual tunnel, thereby solving the technical problem of being unable to accurately prepare over-temperature cable insulation materials that are consistent with the actual fire situation, achieving the purpose of accurately replicating over-temperature cable insulation materials that are consistent with the actual fire situation, and further achieving the technical effect of improving the accuracy of research on the degradation and failure mechanism of cable insulation under high-temperature fire environments.

[0044] (2) Compared with the over-temperature treatment of general materials, this patent fully considers the cooling process, not only considering the triggering time of the fire extinguishing bomb, but also considering the gradual decrease of the equivalent fire source power after the fire is extinguished. In addition, the cable insulation material is inside, and its cooling is also a process of heat transfer through other layers, which is also simulated by simulation, which more realistically reflects the temperature rise change of the insulation layer during the entire fire process.

[0045] (3) In terms of high-temperature preparation of materials, in order to simulate the insulation material being isolated from the air inside the cable and avoid the influence of oxygen, and at the same time to better fit the temperature drop curve and consider the change in the temperature drop rate, a combination of introducing inert gas at room temperature and heating tubes was adopted to achieve more precise control. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0047] Figure 1is a flow chart of a method for preparing a cable insulation material simulating short-term overheating in a fire according to an embodiment of the present invention;

[0048] Figure 2 is a schematic diagram of a coupling relationship in a thermal oxygen reaction of cable combustion provided in an optional manner according to an embodiment of the present invention;

[0049] Figure 3 A schematic diagram of an optional heating box body operation procedure provided according to an embodiment of the present invention;

[0050] Figure 4 is a schematic diagram of an optional simplified cable tunnel fire simulation model provided according to an embodiment of the present invention;

[0051] Figure 5 is a schematic diagram of an optional cable temperature curve at different levels of a cable tunnel simulation model provided according to an embodiment of the present invention;

[0052] Figure 6 is a schematic diagram of an optional over-temperature test platform provided according to an embodiment of the present invention;

[0053] Figure 7 It is a schematic diagram of an optional comparison between simulation of cable insulation layers at different levels and nitrogen cooling provided according to an embodiment of the present invention;

[0054] Figure 8 is an optional preset temperature change curve of the box provided according to an embodiment of the present invention;

[0055] Fig. 9 is a schematic diagram comparing an optional simulation temperature curve and an over-temperature test temperature curve provided according to an embodiment of the present invention;

[0056] Fig.10 is a schematic diagram of a cable insulation material preparation device for simulating short-term overheating in fire according to an embodiment of the present invention;

[0057] Fig.11 is a schematic diagram of an electronic device provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0059] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0060] According to an embodiment of the present invention, there is provided an embodiment of a method for preparing cable insulation materials that simulates short-term overheating in fire. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in an order different from that shown here.

[0061] Figure 1 FIG. 1 is a flow chart of a method for preparing a cable insulation material simulating short-term overheating in a fire according to an embodiment of the present invention. Figure 1 As shown, the method comprises the following steps:

[0062] Step 1: A multi-physics field coupled cable tunnel fire simulation model is established according to a real cable tunnel. The structure of the cable tunnel fire simulation model includes tunnel lining and cable racks for laying cables. Fire-resistant and heat-insulating fire partitions are set at specific layers of the cable racks and target cables are placed.

[0063] In this step, a cable tunnel fire simulation model is established by imitating a real cable tunnel. The fire simulation model contains multiple layers of brackets, and each layer of brackets is placed with cables in different situations. The cables in a certain layer are selected as the target cables and the target cables are simulated. When conducting fire simulation tests on cables, there will be a complex coupling relationship between the temperature field, fluid field, combustion reaction and material transfer. Changes in temperature will affect the physical and chemical properties of the fluid, and the flow of the fluid will affect the mixing of oxygen and pyrolysis products, thereby affecting the rate of the combustion reaction. At the same time, the heat generated by the combustion reaction and the generation and consumption of substances will affect the temperature field and material transfer process. Figure 2 As shown, these coupling relationships can be described by the following variables: Q: heat, T: temperature, C R : Product concentration, C G : reactant concentration, v: fluid velocity, I t: turbulence intensity, ρ: density, μ: viscosity, k: thermal conductivity, c: specific heat capacity.

[0064] The main component of the cable is polyvinyl chloride (C2H3Cl) n and cross-linked polyethylene (C2H4) n The main products of the combustion reaction of polyvinyl chloride are benzene (C6H6), toluene (C7H8), chlorobenzene (C6H5Cl), divinylbenzene (C 10 H 10 ), hydrogen chloride (HCl). Cross-linked polyethylene (C2H4) n The main product of the combustion reaction is pentene (C5H 10 ), butyraldehyde (C4H8O), 1-hexene (C6H 12 ), n-pentane (C5H 12 ), benzene (C6H6), valeraldehyde (C5H 10 O), some of the products will continue to react with oxygen in the air to produce combustion, the reaction formula is as follows:

[0065] 2C6H6+15O2→12CO2+6H2O

[0066] C7H8+9O2→7CO2+4H2O

[0067] 2C6H5Cl+14O2→12CO2+4H2O+2HCl

[0068] 2C 10 H 10 +25O2→20CO2+10H2O

[0069] 2C5H 10 +15O2→10CO2+10H2O

[0070] 2C4H8O+11O2→8CO2+8H2O

[0071] C6H 12 +9O2→6CO2+6H2O

[0072] C5H 12 +8O2→5CO2+6H2O

[0073] C5H 10 O+7O2→5CO2+5H2O

[0074] All solids and fluids in the model obey the energy conservation equation when heat transfer occurs:

[0075]

[0076] Where ρ is the density, Cp is the specific heat capacity, is the rate of change of temperature with time, u is the fluid velocity vector, is the temperature gradient, k is the thermal conductivity, q is the heat flux density vector, and ΣQ is the sum of the heat source terms per unit volume in different domains.

[0077] When the fluid in the model moves, it satisfies the Navier-Stokes equations and the continuity equation:

[0078]

[0079] Where ρ is the fluid density, u is the fluid velocity vector, p is the pressure, I is the unit tensor, K is the stress tensor, F is the volume force, and μ is the dynamic viscosity of the fluid.

[0080] In an optional embodiment, step 1: establishing a cable tunnel fire simulation model coupled with multiple physical fields according to a real cable tunnel, the structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables, setting fire-resistant and heat-insulating fire partitions at specific layers of the cable support and placing target cables, including the following steps:

[0081] Step 1.1: A cable tunnel fire simulation model is established based on a real cable tunnel, wherein the tunnel lining of the cable tunnel fire simulation model is concrete, the outside of the tunnel lining is soil, and both sides of the cable tunnel fire simulation model include multi-layer brackets, on which cables of different voltage levels, different radii and the same length are arranged respectively;

[0082] Step 1.2: Select a specific number of layers in the multi-layer support, arrange fire-resistant and heat-insulating fireproof partitions below and on the sides of the specific number of layers to surround the target cables placed on the specific number of layers, and place the target cables;

[0083] Step 1.3: According to the temperature, environmental pressure and ventilation conditions of a real cable tunnel, the temperature and environmental pressure are set for the cable tunnel fire simulation model, and the laminar inlet and outlet are set at the head and end of the cable tunnel fire simulation model;

[0084] Step 1.4: Select a predetermined fire source layer in the multi-layer support and set a fire source in the predetermined fire source layer.

[0085] Optionally, a cable tunnel fire simulation model is established based on typical cable tunnel dimensions, with internal dimensions L tnl *W tnl *H tnl The tunnel lining is concrete with a thickness of D conc The outer lining is soil with a thickness of D soil . n layers of supports are arranged on both sides of the tunnel, m1, m2...m in sequence from top to bottom nCables of different voltage levels, the cable radius from top to bottom is r c1 、r c2 ……r cn , the length is l c1 , l c2 …… cn , the cable conductor radius is r cond The thickness of conductor shield, insulation layer, insulation shield, metal shield, inner sheath, steel belt armor, and outer sheath are D respectively. cs , D insul , D is , D ms , D ipl , D sta , D epl , select n baf Layer cables, with fireproof partitions arranged below and on the sides, the sizes of which are L dn *W dn *D dn and L sd *W sd *D sd . Set the model ambient temperature T atm and environmental pressure p atm In order to simulate the impact of fire on the cable tunnel, a fire source is set on the upper surface of the kth layer of cables in the model. Considering the ventilation conditions of the tunnel, laminar inlet and outlet are set at the beginning and end of the model. The material property parameters of the tunnel main structure, fireproof partitions and cable layers are shown in the following table:

[0086]

[0087] Step 2: Conduct a fire simulation test on the target cable, record the heating time and cooling time of the fire simulation test, and use the cable tunnel fire simulation model to draw the simulated temperature curve f of the insulation layer of the target cable. m (t), wherein the heating time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time of delayed triggering of the fire extinguishing bomb and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame. The cooling time of the fire simulation test is the time when the temperature of the insulation layer of the target cable drops to the preset temperature.

[0088] In this step, the total simulation time t sum =t rise +t dec Among them, the fire heating time is t rise , including the ambient temperature reaching the trigger temperature T of the fire extinguisher bomb tri Time t tri and the delayed action time t of the fire extinguisher delay The time from the fire extinguishing bomb to the flame extinguishing tact ; Cooling time t dec When the temperature of the insulation layer drops to the set temperature T set The simulation model and related parameters built in step 1 are used for simulation calculation. The simulation needs to consider the temperature change of the cable insulation layer under different wind speeds and different fire source powers.

[0089] In an optional embodiment, step 2: perform a fire simulation test on the target cable, record the heating time and cooling time of the fire simulation test, and use the cable tunnel fire simulation model to draw a simulated temperature curve f of the insulation layer of the target cable. m (t), comprising the following steps:

[0090] Step 2.1: Set the fire source power curve according to the real cable tunnel and set the laminar inlet normal inflow velocity u i Or velocity field u i (x,y,z), start the fire simulation test;

[0091] Step 2.2: Record the temperature rise time of the fire simulation test, where the temperature rise time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed to be triggered, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame;

[0092] Step 2.3: Record the cooling time of the fire simulation test, wherein the cooling time of the fire simulation test is the time it takes for the temperature of the insulation layer of the target cable to drop to a preset temperature after the fire extinguishing bomb is finished extinguishing the fire;

[0093] Step 2.4: Use the cable tunnel fire simulation model to draw the simulated temperature curve f of the insulation layer of the target cable m (t).

[0094] Optionally, set the fire source power curve P according to the actual cable tunnel environment f =g f (t) and the laminar inlet normal inflow velocity u i Or velocity field u i (x,y,z). According to typical fire conditions, determine that the ambient temperature reaches the trigger temperature T of the fire extinguishing bomb tri Time t tri and the delayed action time t of the fire extinguisher delay The time t from the triggering of the fire extinguisher to the extinguishing of the flame act , thus obtaining the cable insulation layer heating time t rise =t tri +t delay +t act After the fire bomb is activated, the cable insulation layer begins to cool down and reaches the set temperature T set The time elapsed is tdec , the fire is considered to be over at this time. Start simulation calculation and draw the temperature change curve of cable insulation layer at different positions under typical working conditions T1=f1(t),T2=f2(t),……T n =f n (t), select the cable insulation layer temperature change curve where the target cable is located as the simulation temperature curve f of the insulation layer of the target cable m (t).

[0095] Step 3: Build an over-temperature test platform based on the cable tunnel fire simulation model, where the over-temperature test platform includes high-temperature processing equipment, vacuum equipment, inert gas generator and air compressor.

[0096] In this step, a material processing test platform is built to simulate a fire short-term over-temperature environment, including high-temperature processing equipment, vacuum equipment, inert gas generator and flow regulating device.

[0097] In an optional embodiment, step 3: building an over-temperature test platform based on a cable tunnel fire simulation model includes the following steps:

[0098] Step 3.1: The high temperature treatment equipment uses a heating box with automatic temperature control function. The heating box is equipped with temperature sensors, heating elements, gas input and output channels, and an adjustable temperature control program. The temperature control program is used to accurately adjust the power of the heating element in a short time to fully reflect the rapid rise and fall of the actual fire temperature;

[0099] Step 3.2: The vacuum pump is used as a vacuum pump, wherein the vacuum pump is used to make the heating box into a vacuum state before heating the sample cable;

[0100] Step 3.3: The inert gas generator uses a nitrogen generator, which is used to supply low-temperature or normal-temperature nitrogen with different volume flow rates to the heating box. By adjusting the size of the flow valve of the heating box, the size of the flow valve of the nitrogen generator, and the pressure gear of the air compressor, the error between the cooling rate of the heating box and the cooling rate of the simulated temperature curve is kept within a predetermined error range.

[0101] Optionally, the high temperature treatment equipment can use a heating box with automatic temperature control function, with an internal volume of L box *W box *H box , the configuration size in the box is L brkt *W brkt *H brktThe box is equipped with temperature sensors, heating elements, gas input and output channels, and a human-machine interface for operators to adjust the temperature control program inside the box. The temperature control program can accurately adjust the power of the heating element in a short time to fully reflect the rapid rise and fall of the actual fire temperature. The parameters that can be set in the heating box temperature control program are temperature target points SP1, SP2, ... SP n , and the time required to reach the temperature target point t1, t2, ... t n ;

[0102] The vacuum pump can be used as the vacuum equipment. Considering that the cable insulation layer does not come into contact with the air when a fire actually occurs, in order to ensure that the sample does not react with the air during the heating process, a vacuum pump or other equipment is used to evacuate the box before heating.

[0103] The inert gas generator can use a nitrogen generator. The nitrogen generator needs an air compressor to provide dry, filtered, water-free and oil-free compressed air as the raw material for nitrogen production. Considering that the cooling rate of the cable insulation layer at different locations is different when a fire actually occurs, and it is not in contact with oxygen, a nitrogen generator and other equipment are used to pass low-temperature or room-temperature nitrogen with different volume flows into the box to make the box cooling rate fit the simulation and isolate oxygen. The nitrogen volume flow Q entering the box is related to the box flow valve size V box , Nitrogen generator flow valve size V nit , Air compressor pressure gear size G air For box 、V nit , G air The size of the nitrogen volume flow Q is adjusted to change the cooling rate in the box.

[0104] Step 4: Set up and simulate the temperature curve f for the high temperature processing equipment of the overtemperature test platform m Over-temperature test temperature curve with the error of (t) within the predetermined error range.

[0105] In this step, by adjusting the box flow valve size V box , Nitrogen generator flow valve size V nit And the air compressor pressure gear G air The size of the nitrogen volume flow rate Q is adjusted to select the appropriate nitrogen volume flow rate Q suit , ensure that the temperature curve set for the heating box is consistent with the simulation temperature curve.

[0106] In an optional embodiment, step 4: setting and simulating a temperature curve f for the high temperature processing equipment of the over-temperature test platform m The over-temperature test temperature curve of the error of (t) is within the predetermined error range, comprising the following steps:

[0107] Step 4.1: Simulate the temperature curve f of the insulation layer of the target cable m (t) selects n temperature points as the n temperature points of the heating box, and draws a point-line graph as the preset temperature curve g of the heating box m (t);

[0108] Step 4.2: Set the preset temperature curve g of the heating box m (t) and simulation temperature curve f m (t) to compare and determine the preset temperature curve g m (t) The time period corresponding to each two temperature points and the simulated temperature curve f m (t) The error between the time periods corresponding to the same two temperature points. If in the time period [t k ,t k+1 ] There is a little bit of memory x The absolute value of the relative error is greater than the predetermined error value E a Then the time period [t k ,t k+1 ] is divided into two periods, and the time period [t k ,t k+1 The temperature point corresponding to the center point of ] is taken as the new temperature point, and the above steps are repeated until the error values ​​of all time periods are less than the predetermined error value E a , generating an updated temperature curve of the heating box;

[0109] Step 4.3: Connect the power supply of each device of the temperature test platform, use a vacuum pump to evacuate the heating box to a vacuum state, start the heating box, and start heating and cooling the heating box according to the updated temperature curve, and draw the actual temperature curve h(t) of the heating box;

[0110] Step 4.4: Compare the actual temperature curve h(t) with the simulated temperature curve f m (t) to determine the actual temperature curve h(t) and the simulated temperature curve f m (t), if at time point t y The error value is greater than the predetermined error value E b , adjust the heating program, cooling program, flow valve of the heating box or flow valve of the nitrogen generator to reduce the time point t y Repeat step 4.4 until the actual temperature curve h(t) is consistent with the simulated temperature curve f m (t) The error value at each time point is less than the predetermined error value E b , and obtain the over-temperature test temperature curve.

[0111] Optionally, select the simulated temperature curve f of the insulation layer of the target cable m(t) is used as the reference curve of this experiment, and n points in the simulation temperature curve are taken as (t1,f m (t1))、(t2,f m (t2))……(t n ,f m (t n )), as the n temperature target points of the box program, draw a point-line diagram as the heating box temperature program change curve SP = g m (t), since each temperature target point directly corresponds to T m =f m (t) The temperature corresponding to each time point, so g m (t1) = f m (t1),g m (t2) = f m (t2),……g m (t n ) = f m (t n ). However, the temperature target points SP of the box program change linearly, so g m (t)≠f m (t).

[0112] In order to verify whether the temperature target point of the selected box program is reasonable, the box preset temperature curve g m (t) and simulation curve f m (t) Compare and determine the acceptable error E of this test a , if a certain time period [t k ,t k+1 ] There is a little bit of memory x The absolute value of the relative error is greater than E a , that is, abs{[g m (t x )-f m (t x )] / f m (t x )}>E a , then the time period is divided into two equal parts to reduce the error, that is, the new point [t new ,f m (t new )], where t new =(t k +t k+1 ) / 2, as the temperature target point of the program, repeat the above steps until the absolute value of the relative error of all time periods is within E a Inside. E a It can reflect the degree of fit between the preset temperature curve of the box and the simulated temperature curve. aThe smaller it is, the closer the preset temperature curve of the box and the simulated temperature curve will be.

[0113] like Figure 3 As shown, turn on the power of each device, use a vacuum pump to evacuate the box, start the box temperature program, and let the box start to heat up. The main components of the heating box temperature automatic control system are the controller and the actuator. The controller compares the current measured temperature PV of the box with the given temperature SV and sends a control signal. The actuator receives the control signal and adjusts the power of the heating tube. The measured temperature PV is the temperature inside the box detected by the temperature sensor, and the given temperature SV is the preset temperature curve SP of the box atmosphere furnace. m (t) The temperature corresponding to the current time. When the measured temperature PV is greater than the given temperature SV, the heating tube power decreases, and when the measured temperature PV is less than the given temperature SV, the heating tube power increases. During the cooling process, in addition to setting the program temperature target point, nitrogen gas must also be introduced.

[0114] Draw the actual temperature curve of the box T = h (t) and compare it with the simulation reference curve T selected this time. m =f m (t) Compare and calculate the relative error to determine the acceptable relative error E for this test b , if the absolute value of the relative error at all time points is within E b In, that is, abs{[h(t)-f m (t)] / f m (t)}≤E b , it means that the sample preparation can effectively correspond to the actual fire situation. x The absolute value of the relative error exceeds E b The case of abs{[h(t x )-f m (t x )] / f m (t x )}>E b , the absolute value of the relative error can be reduced by adjusting the box temperature rise and fall program or the box flow valve and repeating the test. x )>f m (t x ), then increase the nitrogen flow rate during this time period. If h(t x )<f m (t x ), then reduce the nitrogen flow rate in this time period. After the adjustment is completed, repeat the above steps until the absolute value of the relative error at each time point is within E b The over-temperature test temperature curve is obtained.

[0115] Step 5: Perform an over-temperature test on the sample cable according to the over-temperature test temperature curve to obtain the cable insulation material that is overheated for a short time in fire.

[0116] In this step, the temperature control program of the heating box is set according to the over-temperature test temperature curve, and the over-temperature test is carried out on the treated sample cable to obtain the cable insulation material with short-term over-temperature in fire.

[0117] In an optional embodiment, step 5: performing an over-temperature test on a sample cable according to an over-temperature test temperature curve to obtain a cable insulation material that is over-heated for a short time in a fire, comprises the following steps:

[0118] Step 5.1: Set the temperature control program of the heating box according to the over-temperature test temperature curve, wherein, within a predetermined time period before the heating box is heated up, start the air compressor and the nitrogen generator in advance to prepare nitrogen, and when the nitrogen pressure in the nitrogen generator reaches a predetermined pressure value, turn off the air compressor and the nitrogen generator, and wait for the heating box to be heated up. After the heating box is heated up, immediately open the air inlet valve of the heating box and the nitrogen generator to deliver nitrogen to the heating box at a constant speed, and when the gas in the heating box returns to atmospheric pressure, open the pressure regulating valve of the heating box, and at the same time turn on the air compressor to maintain the nitrogen pressure in the nitrogen generator;

[0119] Step 5.2: Perform an over-temperature test on the sample cable placed in the heating box, wherein when preparing the sample cable, use a cable slicer to cut the cable insulation layer into a suitable shape according to a predetermined thickness, and rinse and dry the sample cable;

[0120] Step 5.3: After the temperature control program of the heating box is completed, close the air inlet valve of the heating box, the pressure regulating valve of the heating box, the nitrogen generator and the air compressor, open the box door, take out the sample cable that has passed the temperature test and seal it to obtain the cable insulation material that is short-term overheated in fire.

[0121] Optionally, considering that the nitrogen pressure is low in a short period of time after the nitrogen generator is started, and the output nitrogen rate is slow, the air compressor and nitrogen generator are started in advance to prepare nitrogen a few minutes before the end of the temperature rise section of the box, so as to ensure that the nitrogen generator can output nitrogen to the box at a normal speed at the beginning of the temperature drop section. When the nitrogen pressure in the nitrogen generator reaches a suitable value, the air compressor and nitrogen generator are turned off, and the temperature rise section is waited for to end. When the box enters the temperature drop section, the air inlet valve is immediately opened to allow the nitrogen generator to transport nitrogen into the box, and the air compressor and nitrogen generator are turned on at the same time to maintain the nitrogen pressure in the nitrogen generator, so that the nitrogen generator can transport nitrogen to the box at a constant speed. When the air pressure in the box returns to atmospheric pressure, the pressure regulating valve is opened to maintain the air pressure in the box at the atmospheric pressure level.

[0122] The over-temperature test is carried out on the sample cable placed in the heating box. When preparing the sample, the cable insulation layer can be cut into pieces with a thickness of D using a cable slicer or other suitable tool. smp The sample is rinsed and dried with chemical reagents such as anhydrous ethanol to eliminate the influence of the tool on the test results during the slicing process.

[0123] After the box temperature program is finished, close the air inlet valve, pressure regulating valve, nitrogen generator and air compressor. Open the box door, take out the sample and seal it.

[0124] In an embodiment of the present invention, through the above step 1: a cable tunnel fire simulation model coupled with multiple physical fields is established according to a real cable tunnel, the structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables, and a fire-resistant and heat-insulating fire partition is set at a specific number of layers of the cable support and a target cable is placed; step 2: a fire simulation test is performed on the target cable, the heating time of the fire simulation test and the cooling time of the fire simulation test are recorded, and a simulated temperature curve f of the insulation layer of the target cable is drawn using the cable tunnel fire simulation model m (t), wherein the heating time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed to trigger, and the time when the flame is extinguished after the fire extinguishing bomb is triggered. The cooling time of the fire simulation test is the time when the temperature of the insulation layer of the target cable drops to the preset temperature; Step 3: Build an over-temperature test platform according to the cable tunnel fire simulation model, wherein the over-temperature test platform includes high-temperature processing equipment, vacuum equipment, inert gas generator and air compressor; Step 4: Set the high-temperature processing equipment of the over-temperature test platform with the simulation temperature curve f m (t) is within the predetermined error range of the over-temperature test temperature curve; Step 5: According to the over-temperature test temperature curve, the sample cable is subjected to an over-temperature test to obtain the cable insulation material with short-term over-temperature in the fire. The purpose of simulating cable fires with a more realistic time-varying thermal conductivity is achieved, the technical problem of being unable to accurately prepare over-temperature cable insulation materials that are consistent with actual fire conditions is solved, and the technical effect of improving the accuracy of cable fire simulation is achieved.

[0125] Based on the above embodiments and optional embodiments, the present invention proposes an optional implementation mode:

[0126] Step 1: Figure 4As shown: A simplified cable tunnel fire simulation model is established according to the size of a cable tunnel in a certain area. The internal size is 5m*2.5m*3m, the tunnel lining is concrete with a thickness of 0.1m, and the outer lining is soil with a thickness of 1m. Four layers of brackets are arranged on both sides of the tunnel, and three cables are arranged on each layer. The voltage levels from top to bottom are 10kV, 10kV, 110kV, and 220kV, respectively. The cable radius is 20mm, 20mm, 42mm, and 50mm, respectively. The cable length is 5m, and the cable conductor radius is: 10mm, 10mm, 17mm, 17mm, respectively. The thickness of the cable insulation layer is: 7mm, 7mm, 19mm, 25mm, respectively. The thickness of the cable outer sheath is: 3mm, 3mm, 6mm, and 8mm, respectively. The third layer of cables is selected, and fireproof partitions are arranged below and on the sides. The length is 5m, the thickness is 5mm, the width of the lower partition is 0.45m, and the height of the side panel is 0.2m. The model environment temperature is set to 25℃ and the environment pressure is set to 1atm. To simulate the impact of fire on the cable tunnel, a 0.5m*0.4m plane fire source is set on the upper surface of the 4th layer of cables in the model. Considering the ventilation conditions of the tunnel, laminar inlet and outlet are set at the beginning and end of the cable tunnel fire simulation model. The material attribute parameters of each layer of the tunnel main structure, fireproof partition and simplified cable tunnel fire simulation model are as follows:

[0127]

[0128] Step 2: Set the fire source power curve to P f =1000W(t≤1000s), the laminar inlet normal inflow velocity is u i =0.1m / s, record the time for the ambient temperature to reach the trigger temperature of 68℃ of the fire bomb 880s and the time for the fire bomb to delay action 120s, so that the cable insulation layer heating time is 1000s. After the fire bomb is activated, the cable insulation layer begins to cool down, and it takes about 9000s to reach the set temperature of 100℃, at which time the fire is considered to be over. The total simulation time is 10000s. Start the simulation calculation, such as Figure 5 As shown, the temperature variation curves of the middle thickness of the cable insulation layer close to the ground in the four-story corridor, the three-story corridor against the wall, and the three-story corridor on the opposite side are obtained.

[0129] Step 3: If Figure 6 As shown, an over-temperature test platform is built, including a box-type atmosphere furnace, a vacuum pump, a nitrogen generator, an air compressor and a flow regulating device.

[0130] Step 3.1: The internal volume of the box-type atmosphere furnace is 0.20m*0.15m*0.15m, and a three-layer bracket with a size of 0.18m*0.13m*0.13m is configured in the box to place the sample. The box is equipped with a PT100 platinum electrode sensor, a resistance wire heating tube, an air intake valve and an exhaust valve. The outside is equipped with a human-machine interactive interface for operators to adjust the temperature control program inside the box. The temperature control program can accurately adjust the power of the heating element in a short time to fully reflect the rapid rise and fall of the actual fire temperature. The parameters that can be set in the heating box temperature control program are temperature target points SP1, SP2, ... SP n , and the time required to reach the temperature target point t1, t2, ... t n ;

[0131] Step 3.2: Before heating, use a vacuum pump or other equipment to evacuate the box to ensure that the sample does not react with air during the heating process;

[0132] Step 3.3: Use nitrogen generators and other equipment to introduce low-temperature or room-temperature nitrogen of different volume flows into the box to make the box cooling rate fit the simulation and isolate oxygen. The nitrogen volume flow rate Q entering the box and the box flow valve size V box , Nitrogen generator flow valve size V nit , Air compressor pressure gear size G air For box 、V nit , G air The nitrogen volume flow Q is adjusted by the size of the nitrogen, thereby changing the cooling rate in the box. The air compressor is used to provide the nitrogen generator with water-free and oil-free compressed air after dry filtration.

[0133] Step 4: Adjust the box flow valve size to 80%, the nitrogen generator flow valve size to 100%, and the air compressor pressure gear to 8atm. At this time, the nitrogen volume flow rate is 13.5L / min. Figure 7 As shown, the cooling rate of the box is greater than the maximum cooling rate in the temperature change curve of the cable insulation layer at different positions in step 2. The nitrogen cooling and high temperature treatment equipment power control in step 3 should be combined to ensure that the temperature curve set for the box atmosphere furnace during the overtemperature test is consistent with the simulated temperature curve. The specific steps are as follows:

[0134] Step 4.1: Select the temperature curve of the three-story aisle on the opposite side in the simulation as the reference curve for this test, take 8 points in the simulated temperature curve as the temperature target points of the box program, and draw a point-line graph as the preset temperature change curve of the box SP = g m (t), such as Figure 8 As shown, in order to verify whether the temperature target point selected in step 4.1 is reasonable, the preset temperature curve of the box is compared with the simulated temperature curve to determine that the acceptable error of this test is 5%, as shown in Fig. 9 As shown, the maximum error was 3.18% after testing, which occurred at 35 minutes, so the errors at all time points met the standards.

[0135] Step 5: Set a suitable temperature control program for the box according to the box temperature curve determined in step 4, and place the sample in the appropriate position of the box for over-temperature test.

[0136] Step 5.1: Considering that the nitrogen pressure is low and the nitrogen output rate is slow in a short period of time after the nitrogen generator is started, the air compressor and nitrogen generator are started in advance 2 minutes before the end of the box heating stage to prepare nitrogen, so as to ensure that the nitrogen generator can output nitrogen to the box at a rate of 13.5L / min at the beginning of the cooling stage. When the nitrogen pressure in the nitrogen generator reaches the appropriate value, the air compressor and nitrogen generator are turned off, and the heating stage is waited for to end. When the box enters the cooling stage, the air inlet valve is immediately opened to allow the nitrogen generator to transport nitrogen into the box, and the air compressor and nitrogen generator are turned on at the same time to maintain the nitrogen pressure in the nitrogen generator, so that the nitrogen generator can transport nitrogen to the box at a constant speed. When the air pressure in the box returns to atmospheric pressure, the pressure regulating valve is opened to maintain the air pressure in the box at the atmospheric pressure level.

[0137] Step 5.2: Perform an over-temperature test on the sample cable placed inside the box. When preparing the sample cable, use a cross-linking slicer to cut the cable insulation layer into a circle with a thickness of 10 mm and a radius of 6.5 mm. First, use a soft brush and compressed air to remove large particles of impurities on the surface of the sample, and then use anhydrous ethanol to rinse and dry the sample to eliminate the influence of the equipment on the test results during the slicing process.

[0138] Step 5.3: After the box temperature program is finished running, close the air inlet valve, pressure regulating valve, nitrogen generator and air compressor, open the box door, take out the sample and seal it to obtain the cable insulation material that is overheated for a short time during the fire.

[0139] The above-mentioned optional implementation manner achieves at least the following effects: solves the technical problem of being unable to accurately prepare over-temperature cable insulation materials that are consistent with actual fire conditions, achieves the purpose of accurately replicating over-temperature cable insulation materials that are consistent with actual fire conditions, and then achieves the technical effect of improving the accuracy of research on the degradation and failure mechanism of cable insulation under high temperature fire environments.

[0140] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0141] According to an embodiment of the present invention, there is also provided an apparatus embodiment for implementing a method for preparing a cable insulation material for simulating short-term overheating in a fire. Fig.10A schematic diagram of a cable insulation material preparation device for simulating short-term overheating in a fire according to an embodiment of the present invention is shown in FIG. Fig.10 As shown, the above cable fire simulation device includes a building module 101, a simulation test module 102, an over-temperature test platform building module 103, a setting module 104, and an over-temperature test module 105. The device is described below.

[0142] Establishing module 101, for establishing a cable tunnel fire simulation model with multi-physics field coupling according to a real cable tunnel, wherein the structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables, and fire-resistant and heat-insulating fire partitions are arranged at specific layers of the cable support and target cables are placed;

[0143] The simulation test module 102 is connected to the establishment module 101 and is used to perform a fire simulation test on the target cable, record the heating time and cooling time of the fire simulation test, and use the cable tunnel fire simulation model to draw a simulation temperature curve f of the insulation layer of the target cable. m (t), wherein the heating time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed to trigger, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame. The cooling time of the fire simulation test is the time when the temperature of the insulation layer of the target cable drops to the preset temperature;

[0144] An over-temperature test platform building module 103 is connected to the simulation test module 102 and is used to build an over-temperature test platform, wherein the over-temperature test platform includes a simulated fire source device, a cable bracket, and a high temperature resistant box;

[0145] The setting module 104 is connected to the over-temperature test platform building module 103 and is used to set and simulate the temperature curve f for the high-temperature processing equipment of the over-temperature test platform. m (t) Over-temperature test temperature curve with error within the predetermined error range;

[0146] The over-temperature test module 105 is connected to the setting module 104, and is used to perform an over-temperature test on the sample cable according to the over-temperature test temperature curve to obtain the cable insulation material with short-term over-temperature in fire. In a cable insulation material preparation device for simulating short-term over-temperature in fire provided by an embodiment of the present invention, a setting establishment module is used to establish a cable tunnel fire simulation model with multi-physical field coupling according to a real cable tunnel. The structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables. Fire-resistant and heat-insulating fireproof partitions are set at specific layers of the cable support and the target cable is placed; the simulation test module is used to perform a fire simulation test on the target cable, record the heating time of the fire simulation test and the cooling time of the fire simulation test, and use the cable tunnel fire simulation model to draw a simulated temperature curve f of the insulation layer of the target cable.m (t), wherein the heating time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed to trigger, and the time when the flame is extinguished after the fire extinguishing bomb is triggered. The cooling time of the fire simulation test is the time when the temperature of the insulation layer of the target cable drops to the preset temperature; an over-temperature test platform building module is used to build an over-temperature test platform according to the cable tunnel fire simulation model, wherein the over-temperature test platform includes high-temperature processing equipment, vacuum equipment, inert gas generator and air compressor; a setting module is used to set the high-temperature processing equipment of the over-temperature test platform and the simulation temperature curve f m The over-temperature test temperature curve with an error of (t) within a predetermined error range; the over-temperature test module is used to perform an over-temperature test on the sample cable according to the over-temperature test temperature curve to obtain the cable insulation material with short-term over-temperature in the fire. The purpose of simulating cable fires with a more realistic thermal conductivity that changes with time is achieved, and the technical problem of being unable to accurately prepare over-temperature cable insulation materials that are consistent with actual fire conditions is solved, thereby achieving the technical effect of improving the accuracy of cable fire simulation.

[0147] It should be noted that the above modules can be implemented by software or hardware. For example, for the latter, it can be implemented in the following ways: the above modules can be located in the same processor; or the above modules can be located in different processors in any combination.

[0148] It should be noted that the above-mentioned establishment module 101, simulation test module 102, over-temperature test platform construction module 103, setting module 104, and over-temperature test module 105 correspond to steps 1 to 5 in the embodiment, and the examples and application scenarios implemented by the above-mentioned modules and the corresponding steps are the same, but are not limited to the contents disclosed in the above-mentioned embodiment. It should be noted that the above-mentioned modules as a part of the device can be run in a computer terminal.

[0149] It should be noted that the optional or preferred implementation of this embodiment can refer to the relevant description in the embodiment, which will not be repeated here.

[0150] The above-mentioned cable fire simulation device may also include a processor and a memory, including an establishment module 101, a simulation test module 102, an over-temperature test platform construction module 103, a setting module 104, an over-temperature test module 105, etc., which are all stored in the memory as program units, and the processor executes the above-mentioned program units stored in the memory to realize corresponding functions.

[0151] The processor includes a kernel, which retrieves the corresponding program unit from the memory. There can be one or more kernels. The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one storage chip.

[0152] An embodiment of the present invention provides a non-volatile storage medium on which a program is stored. When the program is executed by a processor, a method for preparing a cable insulation material that simulates short-term overheating due to fire is implemented.

[0153] like Fig.11 An embodiment of the present invention provides an electronic device, the electronic device 10 includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, the following steps are implemented: the memory is used to store a computer program, wherein, when the computer program is executed by the processor, the processor implements the above-mentioned method for preparing cable insulation materials that simulates short-term overheating in fire. The device in this article may be a server, a PC, etc.

[0154] The present invention also provides a computer program product, which, when executed on a data processing device, is suitable for executing a program that initializes the following method steps: computer instructions are executed by the processor to perform the above-mentioned method for preparing cable insulation materials that simulates short-term overheating in fire.

[0155] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0156] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0157] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0158] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0159] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0160] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0161] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0162] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0163] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0164] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a cable insulation material that simulates short-term overheating in a fire, characterized in that: The following steps are involved: Step 1: Establish a multi-physics field coupled cable tunnel fire simulation model according to a real cable tunnel. The structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables. Fire-resistant and heat-insulating fire partitions are set at specific layers of the cable support and target cables are placed. Step 2: Perform a fire simulation test on the target cable, record the heating time and cooling time of the fire simulation test, and use the cable tunnel fire simulation model to draw a simulated temperature curve f of the insulation layer of the target cable. m (t), wherein the heating time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed to trigger, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame, and the cooling time of the fire simulation test is the time when the temperature of the target cable drops to the preset temperature; Step 3: Building an over-temperature test platform according to the cable tunnel fire simulation model, wherein the over-temperature test platform includes high-temperature processing equipment, vacuum equipment, an inert gas generator, and an air compressor; Step 4: Set the high temperature processing equipment of the over-temperature test platform to match the simulation temperature curve f m (t) Over-temperature test temperature curve with the error within the predetermined error range; Step 5: Perform an over-temperature test on the sample cable insulation material according to the over-temperature test temperature curve to obtain the cable insulation material that is overheated for a short time in the fire.

2. The method according to claim 1, characterized in that: Step 1: Establish a multi-physics field coupled cable tunnel fire simulation model according to a real cable tunnel. The structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables. Fire-resistant and heat-insulating fire partitions are set at specific layers of the cable support and target cables are placed, including the following steps: Step 1.1: establishing the cable tunnel fire simulation model according to the real cable tunnel, wherein the tunnel lining of the cable tunnel fire simulation model is concrete, the outside of the tunnel lining is soil, and both sides of the cable tunnel fire simulation model include multi-layer brackets, and cables of different voltage levels, different radii and the same length are arranged on the multi-layer brackets; Step 1.2: Select the specific number of layers in the multi-layer support, arrange fire-resistant and heat-insulating fireproof partitions below and on the sides of the specific number of layers that can surround the target cable placed in the specific number of layers, and place the target cable; Step 1.3: According to the temperature, environmental pressure and ventilation conditions of the real cable tunnel, the temperature and environmental pressure are set for the cable tunnel fire simulation model, and the laminar flow inlet and outlet are set at the head and end of the cable tunnel fire simulation model; Step 1.4: Select a predetermined fire source layer in the multi-layer support, and set a fire source in the predetermined fire source layer.

3. The method according to claim 1, characterized in that: Step 2: Perform a fire simulation test on the target cable, record the heating time and cooling time of the fire simulation test, and use the cable tunnel fire simulation model to draw a simulated temperature curve f of the insulation layer of the target cable. m (t), comprising the following steps: Step 2.1: Set the fire source power curve according to the real cable tunnel and set the laminar inlet normal inflow velocity u i Or velocity field u i (x, y, z), start the fire simulation test; Step 2.2: Record the temperature rise time of the fire simulation test, wherein the temperature rise time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed to be triggered, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame; Step 2.3: Recording the cooling time of the fire simulation test, wherein the cooling time of the fire simulation test is the time it takes for the temperature of the insulation layer of the target cable to drop to the preset temperature after the fire extinguishing bomb is finished extinguishing the fire; Step 2.4: Use the cable tunnel fire simulation model to draw a simulated temperature curve f of the insulation layer of the target cable m (t).

4. The method according to claim 1, characterized in that: Step 3: Building an over-temperature test platform based on the cable tunnel fire simulation model, including the following steps: Step 3.1: The high temperature treatment equipment uses a heating box with an automatic temperature control function. The heating box is equipped with a temperature sensor, a heating element, and a gas input and output channel. The heating box is also equipped with an adjustable temperature control program, wherein the temperature control program is used to accurately adjust the power of the heating element in a short time to fully reflect the rapid rise and fall of the actual fire temperature; Step 3.2: The vacuum pump is selected as the vacuum equipment, wherein the vacuum pump is used to make the heating box into a vacuum state before heating the sample cable; Step 3.3: The inert gas generator is a nitrogen generator, wherein the nitrogen generator is used to introduce low-temperature or normal-temperature nitrogen of different volume flow rates into the heating box, and by adjusting the size of the flow valve of the heating box, the size of the flow valve of the nitrogen generator and the pressure gear of the air compressor, the error between the cooling rate of the heating box and the cooling rate of the simulation temperature curve is maintained within the predetermined error range.

5. The method according to claim 1, characterized in that: Step 4: Set the high temperature processing equipment of the over-temperature test platform to match the simulation temperature curve f m The over-temperature test temperature curve of the error of (t) is within the predetermined error range, comprising the following steps: Step 4.1: Simulate the temperature curve f at the insulation layer of the target cable m (t) selects n temperature points as the n temperature points of the heating box, and draws a point-line graph as the preset temperature curve g of the heating box m (t); Step 4.2: Set the preset temperature curve g of the heating box m (t) and the simulation temperature curve f m (t) compare and determine the preset temperature curve g m (t) The time period corresponding to each two temperature points and the simulated temperature curve f m (t) The error between the time periods corresponding to the same two temperature points. If in the time period [t k ,t k+1 ] There is a little bit of memory x The absolute value of the relative error is greater than the predetermined error value E a Then the time period [t k ,t k+1 ] is divided into two periods, and the time period [t k ,t k+1 The temperature point corresponding to the center point of ] is taken as the new temperature point, and the above steps are repeated until the error values ​​of all time periods are less than the predetermined error value E a , generating an updated temperature curve of the heating box; Step 4.3: Turn on the power of each device of the over-temperature test platform, use the vacuum pump to evacuate the heating box to a vacuum state, start the heating box, and start heating and cooling the heating box according to the updated temperature curve, and draw the actual temperature curve h(t) of the heating box; Step 4.4: Compare the actual temperature curve h(t) with the simulated temperature curve f m (t) to determine the actual temperature curve h(t) and the simulated temperature curve f m (t), if at time point t y The error value is greater than the predetermined error value E b , adjust the heating program, cooling program, flow valve of the heating box or flow valve of the nitrogen generator to reduce the time point t y Repeat the above steps until the actual temperature curve h(t) is equal to the simulated temperature curve f m (t) The error value at each time point is less than the predetermined error value E b , and obtain the over-temperature test temperature curve.

6. The method according to claim 1, characterized in that: Step 5: According to the over-temperature test temperature curve, an over-temperature test is performed on the sample cable to obtain the cable insulation material that is short-term over-temperature in the fire, including the following steps: Step 5.1: The temperature control program of the heating box is set according to the over-temperature test temperature curve, wherein, within a predetermined time period before the heating box is heated up, the air compressor and the nitrogen generator are started in advance to prepare nitrogen, and when the nitrogen pressure in the nitrogen generator reaches a predetermined pressure value, the air compressor and the nitrogen generator are turned off, and the heating box is waited for to be heated up, and after the heating box is heated up, the air inlet valve of the heating box and the nitrogen generator are immediately opened to deliver nitrogen into the heating box at a constant speed, and when the gas in the heating box returns to atmospheric pressure, the pressure regulating valve of the heating box is opened, and the air compressor is turned on at the same time to maintain the nitrogen pressure in the nitrogen generator; Step 5.2: performing the over-temperature test on the sample cable insulation material placed in the heating box, wherein when preparing the sample cable, a cable slicing knife is used to cut the cable insulation layer into a suitable shape according to a predetermined thickness, and the sample cable is rinsed and dried; Step 5.3: After the temperature control program of the heating box is completed, close the air inlet valve of the heating box, the pressure regulating valve of the heating box, the nitrogen generator and the air compressor, open the box door, take out the sample cable insulation material that has undergone the over-temperature test and seal it to obtain the cable insulation material that has been overheated for a short time during the fire.

7. A device for preparing cable insulation materials for simulating short-term overheating in fire, characterized in that: include: Establishing a module for establishing a cable tunnel fire simulation model with multi-physics field coupling according to a real cable tunnel, wherein the structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables, and fire-resistant and heat-insulating fireproof partitions are arranged at specific layers of the cable support and target cables are placed; A simulation test module is used to perform a fire simulation test on the target cable, record the temperature rise time and the temperature drop time of the fire simulation test, and use the cable tunnel fire simulation model to draw a simulation temperature curve f of the insulation layer of the target cable m (t), wherein the heating time of the fire simulation test includes the time when the temperature of the fire simulation test reaches the triggering temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed to be triggered, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame, and the cooling time of the fire simulation test is the time when the temperature of the insulation layer of the target cable drops to the preset temperature; An over-temperature test platform building module is used to build an over-temperature test platform in imitation of the cable tunnel fire simulation model, wherein the over-temperature test platform includes high-temperature processing equipment, vacuum equipment, an inert gas generator and an air compressor; The setting module is used to set the high temperature processing equipment of the over-temperature test platform to the simulation temperature curve f m (t) Over-temperature test temperature curve with the error within the predetermined error range; The over-temperature test module is used to perform an over-temperature test on the sample cable insulation material according to the over-temperature test temperature curve to obtain the cable insulation material that is overheated for a short time in the fire.

8. A non-volatile storage medium, characterized in that: The non-volatile storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor and executed by a method for preparing a cable insulation material simulating short-term overheating in a fire as described in any one of claims 1 to 6.

9. An electronic device, characterized in that: include: One or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement a method for preparing cable insulation materials simulating short-term overheating in fire as described in any one of claims 1 to 6.

10. A computer program product comprising computer instructions, characterized in that The computer instructions are executed by the processor to implement a method for preparing cable insulation materials that simulates short-term overheating in a fire as described in any one of claims 1 to 6.

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