Method for preparing cable insulation materials for simulating short-term overheating during fire

Abstract

This invention discloses a method for preparing cable insulation materials to simulate short-term overheating during a fire. The method includes: Step 1: Establishing a multi-physics coupled cable tunnel fire simulation model based on a real cable tunnel. The cable tunnel fire simulation model includes cable supports, and a target cable is placed at a specific number of layers on the cable supports; Step 2: Conducting a fire simulation test on the target cable and using the cable tunnel fire simulation model to plot the simulated temperature curve f of the target cable. m (t); Step 3: Build an over-temperature test platform based on the cable tunnel fire simulation model; Step 4: Set the temperature curve f for the high-temperature treatment equipment of the over-temperature test platform, matching the simulation temperature curve. m Step 5: Based on the over-temperature test temperature curve, conduct an over-temperature test on the sample cable insulation material to obtain the cable insulation material that experiences short-term over-temperature during a fire. This invention solves the technical problem of not being able to accurately prepare over-temperature cable insulation materials that match actual fire conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of cable tunnel disaster prevention, and more particularly, to a method for preparing a cable insulating material that simulates short-term overheating in a fire. Background Art

[0002] In view of the above problems, according to the causes and development of actual high-voltage cable fires, considering that high-voltage cable tunnels are mainly ignited by high-temperature arcs caused by breakdown faults in intermediate joints, a fire source device that simulates equivalent ignition is developed, the tunnel environment is simulated and arranged, and the fire resistance performance of fire protection products is tested, so as to 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 a cable insulating material that simulates short-term overheating in a fire, so as to at least solve the technical problem of being unable to accurately prepare an overheated cable insulating material that conforms to the actual fire situation.

[0004] According to one aspect of an embodiment of the present invention, a method for preparing a cable insulating material that simulates short-term overheating in a fire is provided, including:

[0005] Step 1: Establish a multi-physics field coupled cable tunnel fire simulation model according to an actual cable tunnel. The structure of the cable tunnel fire simulation model includes a tunnel lining and a cable support for laying cables. Fireproof and heat-insulating fire partitions are provided at specific layers of the cable support, and a target cable is 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 a simulation temperature curve f m (t) of the insulating layer of the target cable. Among them, 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 delayed triggering time of the fire extinguishing bomb, and the time from when the fire extinguishing bomb is triggered to when the flame goes out. The cooling time of the fire simulation test is the time when the temperature of the insulating layer of the target cable drops to a preset temperature;

[0007] Step 3: Build an overheating test platform by imitating the cable tunnel fire simulation model. Among them, the overheating test platform includes a high-temperature treatment device, a vacuum pumping device, an inert gas generator, and an air compressor;

[0008] Step 4: Set an overheating test temperature curve for the high-temperature treatment device of the overheating test platform with an error within a predetermined error range from the simulation temperature curve f m (t);

[0009] Step 5: Based on the over-temperature test temperature curve, conduct an over-temperature test on the sample cable insulation material to obtain the cable insulation material that has undergone short-term over-temperature testing during a fire.

[0010] Optionally, in step 1: a multi-physics coupled cable tunnel fire simulation model is established based on a real cable tunnel. The structure of the cable tunnel fire simulation model includes tunnel lining and cable supports for laying cables. Fire-resistant and heat-insulating fireproof partitions are set at a specific number of layers of the cable supports, and the target cable is placed there. This includes the following steps:

[0011] Step 1.1: Establish a cable tunnel fire simulation model based on a real cable tunnel. The tunnel lining of the cable tunnel fire simulation model is made of concrete, and the outside of the tunnel lining is soil. The cable tunnel fire simulation model has multiple layers of supports on both sides, and cables of different voltage levels, different radii, and the same length are arranged on the multiple layers of supports.

[0012] Step 1.2: Select a specific number of layers in the multi-layer bracket, arrange fire-resistant and heat-insulating fireproof partitions that can surround the target cable placed on the specific layer below and on the side of the specific layer, and place the target cable.

[0013] Step 1.3: Simulate the temperature, environmental pressure, and ventilation conditions of a real cable tunnel, set the temperature and environmental pressure for the cable tunnel fire simulation model, and set laminar flow inlets and outlets at the beginning and end of the cable tunnel fire simulation model;

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

[0015] Optionally, in step 2, a fire simulation test is conducted on the target cable, recording the heating time and cooling time of the fire simulation test, and the simulated temperature curve of the insulation layer of the target cable is plotted using a cable tunnel fire simulation model. m (t), including the following steps:

[0016] Step 2.1: Simulate the fire source power curve of a real cable tunnel, and set the laminar flow inlet normal inflow velocity u. i or velocity field u i (x,y,z), begin fire simulation test;

[0017] Step 2.2: Record the heating time of the fire simulation test, which includes the time it takes for the temperature of the fire simulation test to reach the trigger temperature of the fire extinguishing bomb, the delayed triggering time of the fire extinguishing bomb, 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. 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 has finished extinguishing the fire.

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

[0020] Optionally, in step 3, an over-temperature test platform is built based on 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 a temperature sensor, heating element, and gas input and output channels. The heating box is also equipped with 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 selected as the vacuum equipment. The vacuum pump is used to bring the heating chamber into a vacuum state before heating the sample cable.

[0023] Step 3.3: The inert gas generator is a nitrogen generator. The nitrogen generator is used to introduce low-temperature or room-temperature nitrogen gas at different volume flow rates into the heating chamber. By adjusting the size of the flow valve of the heating chamber, the size of the flow valve of the nitrogen generator, and the pressure setting of the air compressor, the error between the cooling rate of the heating chamber and the cooling rate of the simulated temperature curve is kept within a predetermined error range.

[0024] Optionally, in step 4, the high-temperature treatment equipment of the over-temperature test platform is set with a simulated temperature curve f. m The overtemperature test temperature curve, where the error of (t) is within the predetermined error range, includes the following steps:

[0025] Step 4.1: Simulated temperature profile f of the insulation layer of the target cable m (t) selects n temperature points as the n temperature points of the heating chamber, and plots a dotted line graph as the preset temperature curve g of the heating chamber. m (t);

[0026] Step 4.2: Set the preset temperature curve g of the heating chamber m (t) and the simulated temperature curve f m (t) is compared to determine the preset temperature curve g. m (t) The time intervals corresponding to every two temperature points and the simulated temperature curve f m (t) represents the error between time intervals corresponding to two identical temperature points. If within the time interval [t] k , tk+1 [Memory at a point t] 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 The time period [t] is divided into two segments, and the time period [t] is... k , t k+1 The temperature point corresponding to the center point of the [value] is used as the new temperature point. The above steps are repeated until the error value for all time periods is less than the predetermined error value E. a This generates an updated temperature profile for the heating chamber.

[0027] Step 4.3: Connect the power supply to each device of the temperature test platform, use a vacuum pump to evacuate the heating chamber to a vacuum state, start the heating chamber, and make the heating chamber start to heat up and cool down according to the updated temperature curve, and plot the actual temperature curve h(t) of the heating chamber.

[0028] Step 4.4: Compare the actual temperature curve h(t) with the simulated temperature curve f m By comparing (t), the actual temperature curve h(t) and the simulated temperature curve f are determined. m The error value between (t) is if at time point t y The error value is greater than the predetermined error value E b If necessary, adjust the heating and cooling programs of the heating chamber, the flow valve of the heating chamber, or the flow valve of the nitrogen generator to reduce the time point t. y To find the error value, repeat step 4.4 until the actual temperature curve h(t) matches the simulated temperature curve f. m (t) The error value at each time point is less than the predetermined error value E. b The overheat test temperature curve was obtained.

[0029] Optionally, in step 5, based on the over-temperature test temperature curve, an over-temperature test is conducted on the sample cable to obtain the cable insulation material that withstands short-term over-temperature during a fire, including the following steps:

[0030] Step 5.1: Set the temperature control program of the heating chamber according to the overheat test temperature curve. In the predetermined time period before the heating chamber finishes heating, start the air compressor and nitrogen generator in advance to prepare nitrogen. When the nitrogen pressure in the nitrogen generator reaches the predetermined pressure value, turn off the air compressor and nitrogen generator and wait for the heating chamber to finish heating. After the heating chamber finishes heating, immediately open the air inlet valve and nitrogen generator of the heating chamber to deliver nitrogen into the heating chamber at a constant rate. When the gas in the heating chamber returns to atmospheric pressure, open the pressure regulating valve of the heating chamber and turn on the air compressor at the same time to maintain the nitrogen pressure in the nitrogen generator.

[0031] Step 5.2: Conduct an over-temperature test on the sample cable placed inside the heating chamber. During the preparation of the sample cable, the cable insulation layer is cut into a suitable shape according to the predetermined thickness using a cable slicer, and the sample cable is rinsed and dried.

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

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

[0034] A module is established to create a multi-physics coupled cable tunnel fire simulation model based on a real cable tunnel. The structure of the cable tunnel fire simulation model includes tunnel lining and cable supports for laying cables. Fire-resistant and heat-insulating fireproof partitions are set at a specific number of layers of the cable supports and the target cables are placed there.

[0035] The simulation test module is used to conduct fire simulation tests on the target cable, record the heating and cooling times of the fire simulation test, and plot the simulated temperature curve of the target cable insulation layer using a 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 trigger temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed, 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 insulation layer drops to the preset temperature.

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

[0037] The configuration module is used to set and simulate temperature curves for the high-temperature processing equipment of the over-temperature test platform. m The overtemperature test temperature curve where the error of (t) is within the predetermined error range;

[0038] The over-temperature test module is used to conduct over-temperature tests on sample cables according to the over-temperature test temperature curve to obtain the cable insulation material that has experienced short-term over-temperature during a fire.

[0039] According to another aspect of the present invention, a non-volatile storage medium is provided, which stores a plurality of instructions adapted for loading and executing any one of them by a processor, for a method of preparing cable insulation material simulating short-term overheating during a fire.

[0040] According to another aspect of the present invention, an electronic device is provided, 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 cause the one or more processors to implement any one of the following: a method for preparing cable insulation material simulating short-term overheating during a fire.

[0041] According to another aspect of the present invention, a computer program product is also provided, comprising a computer program that, when executed by a processor, implements a method for preparing cable insulation material simulating short-term overheating during a fire, as described above.

[0042] This invention proposes a method for preparing cable insulation materials that simulates short-term overheating during a fire. The advantages of this invention are:

[0043] (1) Compared with the general high-temperature aging treatment method for cable insulation materials with fixed temperature rise and temperature, this application fully considers the fire extinguishing trigger time under the condition that the fire extinguishing equipment is fully deployed. Based on this, the heating and cooling process of the cable insulation layer in the subsequent process is calculated and the entire process of short-term overheating of the cable under the actual tunnel fire is accurately simulated. This solves the technical problem of not being able to accurately prepare overheated cable insulation materials that match the actual fire situation. It achieves the goal of accurately replicating overheated cable insulation materials that match the actual fire situation, and thus realizes the technical effect of improving the accuracy of the study on the failure mechanism of cable insulation degradation under high temperature fire conditions.

[0044] (2) Compared with the general material overheating treatment, this patent fully considers the cooling process. It not only considers the triggering time of the fire extinguishing bomb, but also 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. This was also simulated using simulation, which more realistically reflects the temperature rise of the insulation layer during the entire fire process.

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

[0046] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0047] Figure 1This is a flowchart of a method for preparing cable insulation material to simulate short-term overheating during a fire, according to an embodiment of the present invention.

[0048] Figure 2 This is a schematic diagram of the coupling relationship in an optional thermo-oxidative reaction of cable combustion according to an embodiment of the present invention;

[0049] Figure 3 This is a schematic diagram of an optional heating chamber operating procedure provided according to an embodiment of the present invention;

[0050] Figure 4 This 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 This is a schematic diagram of cable temperature curves at different levels of a cable tunnel simulation model, provided by an embodiment of the present invention.

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

[0053] Figure 7 This is a schematic diagram comparing simulation and nitrogen cooling of optional different layers of cable insulation provided by an embodiment of the present invention;

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

[0055] Figure 9 This is a schematic diagram comparing an optional simulated temperature curve and an overtemperature test temperature curve according to an embodiment of the present invention.

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

[0057] Figure 11 This is a schematic diagram of an electronic device provided according to an embodiment of the present invention. Detailed Implementation

[0058] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort 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, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

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

[0061] Figure 1 This is a flowchart of a method for preparing cable insulation material to simulate short-term overheating during a fire, according to an embodiment of the present invention. Figure 1 As shown, the method includes the following steps:

[0062] Step 1: Establish a multi-physics coupling cable tunnel fire simulation model based on a real cable tunnel. The structure of the cable tunnel fire simulation model includes tunnel lining and cable supports for laying cables. Fire-resistant and heat-insulating fireproof partitions are set at a specific number of layers of the cable supports and the target cables are placed there.

[0063] In this step, a fire simulation model of a cable tunnel is established, modeled after a real cable tunnel. The simulation model includes multiple layers of supports, each holding cables under different conditions. A cable from a specific layer is selected as the target cable, and a simulation test is conducted on it. During the fire simulation test, complex coupling relationships exist between the temperature field, fluid field, combustion reaction, and mass transfer. Temperature changes affect the physicochemical properties of the fluid, while fluid flow affects the mixing of oxygen and pyrolysis products, thus influencing the rate of the combustion reaction. Simultaneously, the heat generated by the combustion reaction and the formation and consumption of matter affect the temperature field and mass transfer process. For example... 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), and divinylbenzene (C6H5Cl). 10 H 10 Hydrogen chloride (HCl). Cross-linked polyethylene (C2H4) n The main product after the combustion reaction is pentene (C5H). 10 ), butyraldehyde (C4H8O), 1-hexene (C6H 12 ), n-pentane (C5H) 12 ), benzene (C6H6), pentanal (C5H) 10 O), some of the products will continue to react with oxygen in the air in a combustion reaction, as shown in the following equation:

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] In the model, all solids and fluids undergoing heat transfer obey the energy conservation equation:

[0075] ρ

[0076] In the formula, ρ is density, and C p For specific heat capacity, T / t is the rate of change of temperature with time, and u is the fluid velocity vector. T is the temperature gradient, k is the thermal conductivity, q is the heat flux density vector, and ΣQ is the sum of heat source terms per unit volume in different domains.

[0077] The fluid motion in the model satisfies the Navier-Stokes equations and the continuity equation:

[0078]

[0079]

[0080]

[0081] In the formula, 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.

[0082] In one optional embodiment, step 1: Establish a multi-physics coupled cable tunnel fire simulation model based on a real cable tunnel. The structure of the cable tunnel fire simulation model includes a tunnel lining and cable supports for laying cables. Fire-resistant and heat-insulating fireproof partitions are set at a specific number of layers of the cable supports, and the target cable is placed there. This includes the following steps:

[0083] Step 1.1: Establish a cable tunnel fire simulation model based on a real cable tunnel. The tunnel lining of the cable tunnel fire simulation model is made of concrete, and the outside of the tunnel lining is soil. The cable tunnel fire simulation model has multiple layers of supports on both sides, and cables of different voltage levels, different radii, and the same length are arranged on the multiple layers of supports.

[0084] Step 1.2: Select a specific number of layers in the multi-layer bracket, arrange fire-resistant and heat-insulating fireproof partitions that can surround the target cable placed on the specific layer below and on the side of the specific layer, and place the target cable.

[0085] Step 1.3: Simulate the temperature, environmental pressure, and ventilation conditions of a real cable tunnel, set the temperature and environmental pressure for the cable tunnel fire simulation model, and set laminar flow inlets and outlets at the beginning and end of the cable tunnel fire simulation model;

[0086] Step 1.4: Select a predetermined fire source layer in the multi-layer support structure and set the fire source on the predetermined fire source layer.

[0087] Optionally, a cable tunnel fire simulation model can be established based on typical cable tunnel dimensions, with an internal dimension of L. tnl W tnl H tnl The tunnel lining is made of concrete with a thickness of D. conc The outer lining is soil with a thickness of D. soil The tunnel has n layers of supports arranged on both sides, with m1, m2...m arranged sequentially from top to bottom. nFor cables of different voltage levels, the cable radii from top to bottom are r. c1 r c2 ...r cn The lengths are l in sequence c1 l c2 ...l cn The radius of the cable conductor is r cond The thicknesses of the conductor shield, insulation layer, insulation shield, metal shield, inner sheath, steel tape armor, and outer sheath are respectively D. cs D insul D is D ms D ipl D sta D epl Select n baf Layered cables, with fireproof partitions arranged below and on the sides, the dimensions of which are L respectively. dn W dn D dn and L sd W sd D sd Set the model's ambient temperature T. atm and environmental pressure p atm To simulate the impact of a fire on a cable tunnel, a fire source was placed on the upper surface of the k-th layer of cables in the model. Considering the tunnel's ventilation, laminar flow inlets and outlets were placed at the beginning and end of the model. The material properties of the tunnel's main structure, fireproof partitions, and each layer of cables are shown in the table below:

[0088]

[0089] 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 plot the simulated temperature curve of the insulation layer of the target cable. m (t), where the heating time of the fire simulation test includes the time it takes for the temperature of the fire simulation test to reach the trigger temperature of the fire extinguishing bomb, the time for the fire extinguishing bomb to be delayed in triggering, 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 it takes for the temperature of the insulation layer of the target cable to drop to the preset temperature.

[0090] In this step, the total simulation time t sum =t rise +t dec The fire heating time is t. rise This includes the ambient temperature reaching the fire extinguishing bomb's trigger temperature T. tri Time t triThe time t for the delay action of the fire extinguishing grenade delay The time t from when the fire extinguishing bomb is triggered until the flame is extinguished. act Cooling time t dec To reduce the temperature of the insulation layer to a set temperature T set Time required. Simulation calculations are performed using the simulation model and related parameters established in step 1. The simulation needs to consider the temperature changes of the cable insulation layer under different wind speeds and different fire source powers.

[0091] In an optional embodiment, 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 a cable tunnel fire simulation model to plot the simulation temperature curve f of the insulation layer of the target cable. m (t), including the following steps:

[0092] Step 2.1: Simulate the fire source power curve of a real cable tunnel, and set the laminar flow inlet normal inflow velocity u. i or velocity field u i (x,y,z), begin fire simulation test;

[0093] Step 2.2: Record the heating time of the fire simulation test, which includes the time it takes for the temperature of the fire simulation test to reach the trigger temperature of the fire extinguishing bomb, the delayed triggering time of the fire extinguishing bomb, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame.

[0094] Step 2.3: Record the cooling time of the fire simulation test. 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 has finished extinguishing the fire.

[0095] Step 2.4: Use a cable tunnel fire simulation model to plot the simulated temperature curve of the insulation layer of the target cable. m (t).

[0096] Optionally, the fire source power curve P can be set according to the actual cable tunnel environment. f =g f (t) and laminar inlet normal inflow velocity u i or velocity field u i (x,y,z). Determine the ambient temperature to reach the extinguishing bomb trigger temperature T based on typical fire conditions. tri Time t tri The time t for the delay action of the fire extinguishing grenade delay The time t from when the fire extinguishing bomb is triggered until the flame is extinguished. act Thus, the heating time t of the cable insulation layer is obtained. rise =t tri +t delay +t actAfter the fire extinguishing bomb activates, the cable insulation begins to cool down, reaching the set temperature T. set The time elapsed is t dec At this point, the fire is considered over. Simulation calculations begin, and temperature variation curves of the cable insulation layer at different locations under typical operating conditions are plotted: T1=f1(t), T2=f2(t), ... T n =f n (t), the temperature change curve of the cable insulation layer at the location of the target cable is selected as the simulation temperature curve f of the insulation layer of the target cable. m (t).

[0097] Step 3: Construct an over-temperature test platform based on the cable tunnel fire simulation model. The over-temperature test platform includes high-temperature treatment equipment, vacuum equipment, inert gas generator, and air compressor.

[0098] In this step, a material handling test platform simulating a short-term overheated fire environment is built, including high-temperature treatment equipment, vacuum equipment, inert gas generator, and flow regulation device.

[0099] In an optional embodiment, step 3: building an over-temperature test platform based on a cable tunnel fire simulation model, including the following steps:

[0100] Step 3.1: The high-temperature treatment equipment uses a heating box with automatic temperature control function. The heating box is equipped with a temperature sensor, heating element, and gas input and output channels. The heating box is also equipped with 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.

[0101] Step 3.2: The vacuum pump is selected as the vacuum equipment. The vacuum pump is used to bring the heating chamber into a vacuum state before heating the sample cable.

[0102] Step 3.3: The inert gas generator is a nitrogen generator. The nitrogen generator is used to introduce low-temperature or room-temperature nitrogen gas at different volume flow rates into the heating chamber. By adjusting the size of the flow valve of the heating chamber, the size of the flow valve of the nitrogen generator, and the pressure setting of the air compressor, the error between the cooling rate of the heating chamber and the cooling rate of the simulated temperature curve is kept within a predetermined error range.

[0103] Optionally, the high-temperature treatment equipment can be a heating box with automatic temperature control, with an internal volume of L. box W box H box The box is equipped with a size of L. brkt W brkt H brkt The chamber features multi-layered supports for sample placement. It is equipped with temperature sensors, heating elements, and gas input / output channels. An external human-machine interface allows operators to adjust the internal temperature control program, which precisely adjusts the heating element power to accurately reflect the rapid rise and fall of actual fire temperatures. The temperature control program can be set with parameters such as target temperature points SP1, SP2, ... SP2. n And the time required to reach the target temperature point, t1, t2, ... t. n ;

[0104] A vacuum pump can be used for vacuuming. Considering that the cable insulation layer should not be in contact with air during a fire, a vacuum pump or similar device should be used to evacuate the chamber before heating to ensure that the sample does not undergo a thermo-oxidative reaction with air during the heating process.

[0105] An inert gas generator can be used, specifically a nitrogen generator. This generator requires an air compressor to provide dried, filtered, and oil-free compressed air as the nitrogen feedstock. Considering that the cooling rate of cable insulation varies at different locations during a real fire, and that the cable insulation does not come into contact with oxygen, a nitrogen generator or similar equipment is used to introduce low-temperature or room-temperature nitrogen gas at different flow rates into the enclosure. This ensures the cooling rate closely matches the simulation and isolates the enclosure from oxygen. The nitrogen flow rate Q entering the enclosure is related to the size of the enclosure's flow valve V. box Nitrogen generator flow valve size V nit Air compressor pressure setting (G) air This can be addressed by adjusting V. box V nit G air The size of the nitrogen volume flow rate Q is adjusted to change the cooling rate inside the chamber.

[0106] Step 4: Set and simulate temperature curves for the high-temperature treatment equipment of the over-temperature test platform. m The over-temperature test temperature curve where the error of (t) is within the predetermined error range.

[0107] In this step, the size V of the flow valve in the housing is adjusted. box Nitrogen generator flow valve size V nit and the air compressor pressure setting G air The size of the nitrogen volume flow rate Q is used to adjust the nitrogen volume flow rate Q. A suitable nitrogen volume flow rate Q is selected. suit This ensures that the temperature profile set for the heating chamber matches the simulated temperature profile.

[0108] In an optional embodiment, step 4: setting and simulating temperature curves for the high-temperature treatment equipment of the over-temperature test platform. mThe overtemperature test temperature curve, where the error of (t) is within the predetermined error range, includes the following steps:

[0109] Step 4.1: Simulated temperature profile f of the insulation layer of the target cable m (t) selects n temperature points as the n temperature points of the heating chamber, and plots a dotted line graph as the preset temperature curve g of the heating chamber. m (t);

[0110] Step 4.2: Set the preset temperature curve g of the heating chamber m (t) and the simulated temperature curve f m (t) is compared to determine the preset temperature curve g. m (t) The time intervals corresponding to every two temperature points and the simulated temperature curve f m (t) represents the error between time intervals corresponding to two identical temperature points. If within the time interval [t] k , t k+1 [Memory at a point t] 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 The time period [t] is divided into two segments, and the time period [t] is... k , t k+1 The temperature point corresponding to the center point of the [value] is used as the new temperature point. The above steps are repeated until the error value for all time periods is less than the predetermined error value E. a This generates an updated temperature profile for the heating chamber.

[0111] Step 4.3: Connect the power supply to each device of the temperature test platform, use a vacuum pump to evacuate the heating chamber to a vacuum state, start the heating chamber, and make the heating chamber start to heat up and cool down according to the updated temperature curve, and plot the actual temperature curve h(t) of the heating chamber.

[0112] Step 4.4: Compare the actual temperature curve h(t) with the simulated temperature curve f m By comparing (t), the actual temperature curve h(t) and the simulated temperature curve f are determined. m The error value between (t) is if at time point t y The error value is greater than the predetermined error value E b If necessary, adjust the heating and cooling programs of the heating chamber, the flow valve of the heating chamber, or the flow valve of the nitrogen generator to reduce the time point t. y To find the error value, repeat step 4.4 until the actual temperature curve h(t) matches the simulated temperature curve f. m (t) The error value at each time point is less than the predetermined error value E. b The overheat test temperature curve was obtained.

[0113] Optionally, select the simulated temperature profile f of the insulation layer of the target cable. m (t) is used as the reference curve for this experiment. n points from the simulated temperature curve are taken and denoted as (t1, f). m (t1)), (t2, f m (t2))……(t n , f m (t n Using n temperature target points as the parameters of the chamber program, a dotted line graph is plotted as the temperature program change curve of the heating chamber, SP=g. m (t), since each temperature target point directly corresponds to T m =f m (t) represents the temperature at each time point, therefore 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 in the chamber program change linearly, therefore g m (t)≠f m (t).

[0114] To verify whether the selected temperature target point of the enclosure program is reasonable, the preset temperature curve g of the enclosure will be used. m (t) and simulation curve f m (t) Comparison to determine the acceptable error E of this experiment. a If a certain time period [t] k , t k+1 [Memory at a point t] 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 To reduce error, the time period is divided into two equal segments, i.e., a new point [t] is added. new , f m (t new )], where t new =(t k +t k+1 Take ) / 2 as the target temperature point for the program, and repeat the above steps until the absolute value of the relative error for all time periods is within E. a Inside. E aIt can reflect the degree of fit between the preset temperature curve and the simulated temperature curve of the chamber. The selected E... a The smaller the value, the better the fit between the preset temperature curve and the simulated temperature curve of the chamber.

[0115] like Figure 3 As shown, power is switched on to all equipment, and a vacuum pump is used to evacuate the chamber to a vacuum level. The chamber temperature program is then started, causing the chamber to begin heating. The main components of the automatic temperature control system for the heating chamber are the controller and the actuator. The controller compares the current measured temperature PV of the chamber with the set temperature SV and sends a control signal. The actuator receives the control signal and adjusts the heating element power accordingly. The measured temperature PV is the temperature inside the chamber detected by the temperature sensor, and the set temperature SV is the preset temperature curve SP=g for the chamber atmosphere furnace. m (t) represents the temperature at the current time. When the measured temperature PV is greater than the given temperature SV, the heating element power decreases; when the measured temperature PV is less than the given temperature SV, the heating element power increases. During the cooling process, in addition to setting the program temperature target point, nitrogen gas also needs to be introduced.

[0116] Plot the actual temperature curve of the chamber, T=h(t), and compare it with the selected simulation reference curve T. m =f m (t) Compare and calculate the relative error to determine the acceptable relative error E for this experiment. b If the absolute value of the relative error at all time points is within E b Inside, that is, abs{[h(t)-f m (t)] / f m (t)}≤E b This indicates that the sample preparation effectively corresponds to the actual fire situation. If a certain point t occurs... x The absolute value of the relative error exceeds E b The case where 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 chamber's heating and cooling program or the chamber's flow valve and repeating the test. If h(t) x )>f m (t x If h(t) is increased, then the nitrogen flow rate during that time period will be increased. x )<f m (t x If the nitrogen flow rate is below a certain threshold, reduce the nitrogen flow rate for that time period. Repeat the above steps after adjustment until the absolute value of the relative error at each time point is within E. b The overheating test temperature curve was obtained.

[0117] Step 5: Based on the over-temperature test temperature curve, conduct an over-temperature test on the sample cable to obtain the cable insulation material that can withstand short-term over-temperature during a fire.

[0118] In this step, the temperature control program of the heating chamber 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 that can withstand short-term over-temperature in a fire.

[0119] In an optional embodiment, step 5: Based on the over-temperature test temperature curve, an over-temperature test is conducted on the sample cable to obtain the cable insulation material that withstands short-term over-temperature during a fire, including the following steps:

[0120] Step 5.1: Set the temperature control program of the heating chamber according to the overheat test temperature curve. In the predetermined time period before the heating chamber finishes heating, start the air compressor and nitrogen generator in advance to prepare nitrogen. When the nitrogen pressure in the nitrogen generator reaches the predetermined pressure value, turn off the air compressor and nitrogen generator and wait for the heating chamber to finish heating. After the heating chamber finishes heating, immediately open the air inlet valve and nitrogen generator of the heating chamber to deliver nitrogen into the heating chamber at a constant rate. When the gas in the heating chamber returns to atmospheric pressure, open the pressure regulating valve of the heating chamber and turn on the air compressor at the same time to maintain the nitrogen pressure in the nitrogen generator.

[0121] Step 5.2: Conduct an over-temperature test on the sample cable placed inside the heating chamber. During the preparation of the sample cable, the cable insulation layer is cut into a suitable shape according to the predetermined thickness using a cable slicer, and the sample cable is rinsed and dried.

[0122] Step 5.3: After the temperature control program of the heating chamber is completed, close the air inlet valve, pressure regulating valve, nitrogen generator and air compressor of the heating chamber, open the chamber door, take out the sample cable that has undergone the temperature test and seal it to obtain the cable insulation material for short-term overheating in a fire.

[0123] Optionally, considering the low nitrogen pressure and slow nitrogen output rate in the short period after the nitrogen generator starts, the air compressor and nitrogen generator should be started a few minutes before the end of the heating phase to ensure that the nitrogen generator can output nitrogen to the chamber at a normal rate when the cooling phase begins. Once the nitrogen pressure inside the nitrogen generator reaches a suitable value, the air compressor and nitrogen generator should be turned off, and the heating phase should be allowed to finish. When the chamber enters the cooling phase, the inlet valve should be opened immediately to allow the nitrogen generator to supply nitrogen into the chamber. Simultaneously, the air compressor and nitrogen generator should be turned on to maintain the nitrogen pressure inside the generator, thus ensuring a constant nitrogen supply rate. Once the pressure inside the chamber returns to atmospheric pressure, the pressure regulating valve should be opened to maintain the pressure at atmospheric level.

[0124] Overheating tests were conducted on sample cables placed inside a heating chamber. During sample preparation, a suitable tool, such as a cable slicer, was used to cut the cable insulation layer into sections with a thickness of D. smp The sample was then rinsed and dried using chemical reagents such as anhydrous ethanol to eliminate the influence of tools on the test results during the slicing process.

[0125] After the chamber temperature program finishes running, shut off the inlet valve, pressure regulating valve, nitrogen generator, and air compressor. Open the chamber door, remove the sample, and seal it.

[0126] In this embodiment of the invention, step 1 involves establishing a multi-physics coupled cable tunnel fire simulation model based on a real cable tunnel. The structure of the cable tunnel fire simulation model includes a tunnel lining and cable supports for laying cables. Fire-resistant and heat-insulating fireproof partitions are installed at specific layers of the cable supports, and the target cable is placed there. Step 2 involves conducting a fire simulation test on the target cable, recording the heating time and cooling time of the fire simulation test, and using the cable tunnel fire simulation model to plot the simulation temperature curve f of the insulation layer of the target cable. m (t), where the heating time of the fire simulation test includes the time it takes for the temperature of the fire simulation test to reach the trigger temperature of the fire extinguishing bomb, the time for the fire extinguishing bomb to be delayed in triggering, 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 it takes for the temperature of the insulation layer of the target cable to drop to the preset temperature. Step 3: Build an over-temperature test platform based on the cable tunnel fire simulation model. The over-temperature test platform includes high-temperature treatment equipment, vacuum equipment, inert gas generator, and air compressor. Step 4: Set the high-temperature treatment equipment of the over-temperature test platform with the simulation temperature curve f. m Step 5: Based on the over-temperature test temperature curve, conduct an over-temperature test on the sample cable to obtain the cable insulation material for short-term over-temperature during a fire. This achieves the goal of simulating cable fires using a more realistic thermal conductivity that changes over time, solves the technical problem of not being able to accurately prepare over-temperature cable insulation materials that match actual fire conditions, and thus improves the accuracy of cable fire simulation.

[0127] Based on the above embodiments and optional embodiments, the present invention proposes an optional implementation method:

[0128] Step 1: As Figure 4 As shown: A simplified simulation model of a cable tunnel fire was established based on the dimensions of a cable tunnel in a certain region, with an internal dimension of 5m. 2.5m The tunnel has a 3m diameter, with a 0.1m thick concrete lining and a 1m thick soil exterior. Four layers of supports are installed on both sides of the tunnel, each layer carrying three cables. From top to bottom, the voltage levels are 10 kV, 10 kV, 110 kV, and 220 kV, with cable radii of 20 mm, 20 mm, 42 mm, and 50 mm respectively. All cables are 5m long, with conductor radii of 10 mm, 10 mm, 17 mm, and 17 mm respectively. Insulation thicknesses are 7 mm, 7 mm, 19 mm, and 25 mm respectively, and outer sheath thicknesses are 3 mm, 3 mm, 6 mm, and 8 mm respectively. The third layer of cables is selected, and fireproof partitions are installed below and to the sides, each 5m long and 5mm thick. The width of the lower partition is 0.45m, and the height of the side partitions is 0.2m. The model's ambient temperature is set at 25℃ and the ambient pressure at 1 atm. To simulate the impact of fire on the cable tunnel, a 0.5m fireproof partition is installed on the upper surface of the fourth layer of cables in the model. A 0.4m planar fire source was used. Considering the tunnel's ventilation, laminar flow inlets and outlets were installed at both ends of the cable tunnel fire simulation model. The material properties of the tunnel's main structure, fireproof partitions, and each layer of the simplified cable tunnel fire simulation model are shown in the table below:

[0129]

[0130] Step 2: Set the fire source power curve to P f =1000W (t≤1000s), laminar inlet normal inflow velocity is u i =0.1m / s, record the time (880s) for the ambient temperature to reach the fire extinguishing grenade trigger temperature of 68℃ and the fire extinguishing grenade delay time (120s), thus obtaining the cable insulation layer heating time as 1000s. After the fire extinguishing grenade activates, the cable insulation layer begins to cool down, taking approximately 9000s to reach the set temperature of 100℃, at which point the fire is considered to have ended. The total simulation time is 10000s. Start the simulation calculation, as follows... Figure 5 As shown, the temperature variation curves of the cable insulation layer near the ground in the four-layer corridor, the three-layer wall-mounted corridor, and the three-layer opposite corridor are obtained.

[0131] Step 3: As Figure 6 As shown, an over-temperature test platform was constructed, including a box-type atmosphere furnace, a vacuum pump, a nitrogen generator, an air compressor, and a flow regulation device.

[0132] Step 3.1: The internal volume of the box-type atmosphere furnace is 0.20m³. 0.15m 0.15m, with an internal dimension of 0.18m. 0.13m A three-tiered, 0.13m support frame is used to hold samples. The chamber is equipped with a PT100 platinum electrode sensor, resistance wire heating element, air inlet valve, and air extraction valve. An external human-machine interface allows operators to adjust the internal temperature control program, which can precisely adjust the heating element power in a short time to fully reflect the rapid rise and fall of the actual fire temperature. The temperature control program can be set with parameters such as temperature target points SP1, SP2, ... SP n And the time required to reach the target temperature point, t1, t2, ... t n ;

[0133] Step 3.2: Before heating, use a vacuum pump or other equipment to evacuate the chamber to ensure that the sample does not undergo a thermo-oxygen reaction with the air during the heating process;

[0134] Step 3.3: Use a nitrogen generator or similar equipment to introduce low-temperature or room-temperature nitrogen gas at different flow rates into the chamber to ensure the cooling rate matches the simulation and to isolate oxygen. The nitrogen flow rate Q entering the chamber is related to the size of the chamber's flow valve V. box Nitrogen generator flow valve size V nit Air compressor pressure setting (G) air This can be addressed by adjusting V. box V nit G air The nitrogen volumetric flow rate Q is adjusted by the magnitude of the nitrogen concentration, thereby changing the cooling rate inside the chamber. An air compressor is used to provide the nitrogen generator with dried, filtered, and oil-free compressed air.

[0135] Step 4: Adjust the flow valve of the gas chamber to 80%, the flow valve of the nitrogen generator to 100%, and the air compressor pressure setting to 8 atm. At this point, the nitrogen volumetric flow rate is 13.5 L / min. Figure 7 As shown, the cooling rate of the enclosure is greater than the maximum cooling rate in the temperature change curves of the cable insulation layer at different locations in step 2. The power control of the nitrogen cooling and high-temperature treatment equipment in step 3 should be considered to ensure that the temperature curve set for the box-type atmosphere furnace during the over-temperature test is consistent with the simulated temperature curve. The specific steps are as follows:

[0136] Step 4.1: Select the temperature curve of the three-story passageway on the opposite side in the simulation as the reference curve for this experiment. Take 8 points from the simulation temperature curve as the temperature target points of the chamber program, and draw a dot-line graph as the preset temperature change curve SP=g of the chamber. m (t), such as Figure 8 As shown, to verify whether the temperature target point selected in step 4.1 is reasonable, the preset temperature curve of the chamber is compared with the simulated temperature curve, and the acceptable error for this test is determined to be 5%. Figure 9 As shown, the maximum error was 3.18% after testing, which occurred at 35 minutes. Therefore, the errors at all time points meet the standard.

[0137] Step 5: Based on the chamber temperature curve determined in Step 4, set a suitable temperature control program for the chamber and place the sample in the appropriate position in the chamber for overtemperature testing.

[0138] Step 5.1: Considering the low nitrogen pressure and slow nitrogen output rate in the short period after the nitrogen generator starts, the air compressor and nitrogen generator are started 2 minutes before the end of the heating phase to ensure that the nitrogen generator can output nitrogen to the chamber at a rate of 13.5 L / min at the start of the cooling phase. Once the nitrogen pressure inside the nitrogen generator reaches a suitable value, the air compressor and nitrogen generator are turned off, and the heating phase ends. When the chamber enters the cooling phase, the inlet valve is immediately opened to allow the nitrogen generator to supply nitrogen into the chamber. Simultaneously, the air compressor and nitrogen generator are turned on to maintain the nitrogen pressure inside the generator, thus ensuring a constant nitrogen supply rate. Once the chamber pressure returns to atmospheric pressure, the pressure regulating valve is opened to maintain the chamber pressure at atmospheric level.

[0139] Step 5.2: Perform an over-temperature test on the sample cable placed inside the box. When preparing the sample cable, a cross-linking slicer can be used to cut the cable insulation layer into circles with a thickness of 10 mm and a radius of 6.5 mm. First, use a soft brush and compressed air to remove large particulate impurities from the sample surface. Then, rinse and dry the sample with anhydrous ethanol to eliminate the influence of the equipment on the test results during the slicing process.

[0140] Step 5.3: After the chamber temperature program finishes running, close the air inlet valve, pressure regulating valve, nitrogen generator and air compressor, open the chamber door, take out the sample and seal it to obtain the cable insulation material that has been subjected to short-term overheating during a fire.

[0141] The above optional implementation methods achieve at least the following effects: they solve the technical problem of not being able to accurately prepare overheated cable insulation materials that match actual fire conditions, achieve the goal of accurately replicating overheated cable insulation materials that match actual fire conditions, and thus improve the accuracy of research on the degradation and failure mechanism of cable insulation under high-temperature fire conditions.

[0142] It should be noted that the steps shown in the flowchart in 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 a different order than that shown here.

[0143] According to embodiments of the present invention, an apparatus embodiment for implementing a method for preparing cable insulation materials under simulated short-term overheating during a fire is also provided. Figure 10 A schematic diagram of a cable insulation material preparation apparatus for simulating short-term overheating during a fire, according to an embodiment of the present invention, is shown below. Figure 10As shown, the above-mentioned cable fire simulation device includes a setup module 101, a simulation test module 102, an over-temperature test platform construction module 103, a setting module 104, and an over-temperature test module 105. The device will be described below.

[0144] Module 101 is established to create a multi-physics coupled cable tunnel fire simulation model based on a real cable tunnel. The structure of the cable tunnel fire simulation model includes tunnel lining and cable supports for laying cables. Fire-resistant and heat-insulating fireproof partitions are set at a specific number of layers of the cable supports and the target cable is placed there.

[0145] The simulation test module 102, connected to the setup module 101, is used to conduct fire simulation tests on the target cable, record the heating and cooling times of the fire simulation test, and plot the simulation temperature curve of the insulation layer of the target cable using the cable tunnel fire simulation model. m (t), where the heating time of the fire simulation test includes the time it takes for the temperature of the fire simulation test to reach the trigger temperature of the fire extinguishing bomb, the time for the fire extinguishing bomb to be delayed, 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 it takes for the temperature of the target cable insulation layer to drop to the preset temperature.

[0146] The over-temperature test platform construction module 103 is connected to the simulation test module 102 and is used to build an over-temperature test platform. The over-temperature test platform includes a simulated fire source device, a cable bracket, and a high-temperature resistant chamber.

[0147] The setting module 104, connected to the over-temperature test platform construction module 103, is used to set and simulate the temperature curve f for the high-temperature processing equipment of the over-temperature test platform. m The overtemperature test temperature curve where the error of (t) is within the predetermined error range;

[0148] The over-temperature test module 105, connected to the setting module 104, is used to conduct 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 a fire. In the cable insulation material preparation device for simulating short-term over-temperature in a fire provided in this embodiment of the invention, a setting module is used to establish a multi-physics coupled cable tunnel fire simulation model based on 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 a specific number of layers on the cable support, and the target cable is placed there. The simulation test module is used to 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 plot the simulation temperature curve f of the insulation layer of the target cable. m(t), where the heating time of the fire simulation test includes the time it takes for the temperature of the fire simulation test to reach the trigger temperature of the fire extinguishing bomb, the time for the fire extinguishing bomb to be delayed in triggering, 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 it takes for the temperature of the insulation layer of the target cable to drop to the preset temperature. The over-temperature test platform construction 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 treatment equipment, vacuum equipment, an inert gas generator, and an air compressor. The setting module is used to set the high-temperature treatment equipment of the over-temperature test platform with the simulation temperature curve f. m The over-temperature test temperature curve (t) is within a predetermined error range; the over-temperature test module is used to conduct over-temperature tests on sample cables based on the over-temperature test temperature curve to obtain cable insulation materials that experience short-term over-temperature during fire. This achieves the goal of simulating cable fires using a more realistic thermal conductivity that changes over time, solves the technical problem of not being able to accurately prepare over-temperature cable insulation materials that match actual fire conditions, and thus improves the accuracy of cable fire simulation.

[0149] 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.

[0150] It should be noted that the above-mentioned modules, including 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 embodiments. The examples and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the content disclosed in the above embodiments. It should be noted that the above modules, as part of the device, can run on a computer terminal.

[0151] It should be noted that the optional or preferred implementation methods of this embodiment can be found in the relevant descriptions in the embodiments, and will not be repeated here.

[0152] The aforementioned cable fire simulation device may also include a processor and a memory. The establishment module 101, simulation test module 102, over-temperature test platform construction module 103, setting module 104, and over-temperature test module 105 are all stored in the memory as program units. The processor executes the aforementioned program units stored in the memory to realize the corresponding functions.

[0153] The processor contains a core that retrieves the corresponding program unit from memory. One or more cores may be configured. Memory may include non-persistent memory in computer-readable media, random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory includes at least one memory chip.

[0154] This invention provides a non-volatile storage medium storing a program that, when executed by a processor, implements a method for preparing cable insulation materials that simulates short-term overheating during a fire.

[0155] like Figure 11 This invention provides an electronic device 10, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs the following steps: the memory is used to store a computer program, wherein when the computer program is executed by the processor, the processor performs the above-mentioned method for preparing cable insulation material simulating short-term overheating during a fire. The device in this article may be a server, PC, etc.

[0156] The present invention also provides a computer program product, which, when executed on a data processing device, is suitable for executing an initialization program having the following method steps: computer instructions are executed by a processor to perform the above-described method for preparing cable insulation material under simulated short-term overheating during a fire.

[0157] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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.

[0158] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0159] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0160] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0161] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0162] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0163] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, 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 technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0164] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0165] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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.

[0166] The above are merely embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for preparing cable insulation material to simulate short-term overheating during a fire, characterized in that, Includes the following steps: Step 1: Establish a multi-physics coupling cable tunnel fire simulation model based on a real cable tunnel. The structure of the cable tunnel fire simulation model includes tunnel lining and cable supports for laying cables. Fire-resistant and heat-insulating fireproof partitions are set at a specific number of layers of the cable supports, and the target cable is placed there. 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 plot the 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 trigger temperature of the fire extinguishing bomb, the time when the fire extinguishing bomb is delayed in triggering, 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: Construct an over-temperature test platform based on the cable tunnel fire simulation model. The over-temperature test platform includes a high-temperature treatment device, a vacuum pump, an inert gas generator, and an air compressor. The high-temperature treatment device is a heating box with automatic temperature control, the vacuum pump is a vacuum pump, and the inert gas generator is a nitrogen generator. Step 4: Set the high-temperature treatment equipment of the over-temperature test platform to match the simulated temperature curve f. m The overtemperature test temperature curve where the error of (t) is within the predetermined error range; Step 5: Based on the over-temperature test temperature curve, conduct an over-temperature test on the sample cable insulation material to obtain the cable insulation material that has undergone short-term over-temperature during a fire. Step 4: Set the high-temperature treatment equipment of the over-temperature test platform to the simulated temperature curve f. m The overtemperature test temperature curve, where the error of (t) is within the predetermined error range, includes the following steps: 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 chamber, and plots a dotted line graph as the preset temperature curve g of the heating chamber. m (t); Step 4.2: Set the preset temperature curve g of the heating chamber m (t) and the simulated temperature curve f m (t) is compared to determine the preset temperature curve g. m (t) The time interval corresponding to every two temperature points and the simulated temperature curve f m (t) represents the error between time intervals corresponding to two identical temperature points. If within the time interval [t] k , t k+1 [Memory at a point t] 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 The time period [t] is divided into two segments, and the time period [t] is... k , t k+1 The temperature point corresponding to the center point of the [value] is used as the new temperature point. The above steps are repeated until the error value for all time periods is less than the predetermined error value E. a The updated temperature profile of the heating chamber is generated. Step 4.3: Connect the power supply to each device of the over-temperature test platform, use the vacuum pump to evacuate the heating chamber to a vacuum state, start the heating chamber, and start heating and cooling the heating chamber according to the updated temperature curve, and plot the actual temperature curve h(t) of the heating chamber. Step 4.4: Compare the actual temperature curve h(t) with the simulated temperature curve f m By comparing (t), the actual temperature curve h(t) and the simulated temperature curve f are determined. m The error value between (t) is if at time point t y The error value is greater than the predetermined error value E b Then adjust the heating program and cooling program of the heating chamber, the flow valve of the heating chamber, or the flow valve of the nitrogen generator to reduce the time point t. y To find the error value, repeat the above steps until the actual temperature curve h(t) matches the simulated temperature curve f. m (t) The error value at each time point is less than the predetermined error value E. b The overheat test temperature curve was obtained.

2. The method according to claim 1, characterized in that: Step 1: Establish a multi-physics coupled cable tunnel fire simulation model based on a real cable tunnel. The structure of the cable tunnel fire simulation model includes tunnel lining and cable supports for laying cables. Fire-resistant and heat-insulating fireproof partitions are installed at specific layers of the cable supports, and the target cable is placed there. This includes the following steps: Step 1.1: Establish a cable tunnel fire simulation model based on the real cable tunnel. The tunnel lining of the cable tunnel fire simulation model is made of concrete, and the outside of the tunnel lining is soil. The cable tunnel fire simulation model has multiple layers of supports on both sides, and cables of different voltage levels, different radii, and the same length are arranged on the multiple layers of supports respectively. Step 1.2: Select the specific number of layers in the multi-layer bracket, arrange fire-resistant and heat-insulating fireproof partitions that can surround the target cable placed in the specific number of layers below and on the sides, and place the target cable thereon; Step 1.3: Based on the temperature, ambient pressure, and ventilation conditions of the real cable tunnel, set the temperature and ambient pressure for the cable tunnel fire simulation model, and set laminar flow inlet and outlet at the beginning 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: 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 plot the simulation temperature curve f of the insulation layer of the target cable. m (t), including the following steps: Step 2.1: Simulate the actual cable tunnel to set the fire source power curve, and set the laminar flow inlet normal inflow velocity u. i or velocity field u i (x,y,z), begin the fire simulation test; Step 2.2: Record the heating time of the fire simulation test, wherein the heating time of the fire simulation test includes the time it takes for the temperature of the fire simulation test to reach the trigger temperature of the fire extinguishing bomb, the delayed triggering time of the fire extinguishing bomb, and the time from the triggering of the fire extinguishing bomb to the extinguishing of the flame. 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 the preset temperature after the fire extinguishing bomb has finished extinguishing the fire; Step 2.4: Use the cable tunnel fire simulation model to plot the 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: Construct an over-temperature test platform based on the aforementioned cable tunnel fire simulation model, including the following steps: Step 3.1: The heating box is equipped with a temperature sensor, a heating element, and a gas input / output channel. The heating box is also equipped with an adjustable temperature control program, which is used to precisely 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 used to bring the heating chamber into a vacuum state before heating the sample cable; Step 3.3: The nitrogen generator is used to introduce low-temperature or room-temperature nitrogen gas at different volume flow rates into the heating chamber. By adjusting the size of the flow valve of the heating chamber, the size of the flow valve of the nitrogen generator, and the pressure setting of the air compressor, the error between the cooling rate of the heating chamber and the cooling rate of the simulated temperature curve is kept within the predetermined error range.

5. The method according to claim 1, characterized in that: Step 5: Based on the over-temperature test temperature curve, conduct an over-temperature test on the sample cable to obtain the cable insulation material that can withstand short-term over-temperature during a fire, including the following steps: Step 5.1: Set the temperature control program of the heating chamber according to the overheat test temperature curve. In the predetermined time period before the heating chamber finishes heating, start the air compressor and the nitrogen generator in advance to prepare nitrogen. When the nitrogen pressure in the nitrogen generator reaches the predetermined pressure value, turn off the air compressor and the nitrogen generator and wait for the heating chamber to finish heating. After the heating chamber finishes heating, immediately open the air inlet valve of the heating chamber and the nitrogen generator to deliver nitrogen into the heating chamber at a constant rate. When the gas in the heating chamber returns to atmospheric pressure, open the pressure regulating valve of the heating chamber and turn on the air compressor at the same time to maintain the nitrogen pressure in the nitrogen generator. Step 5.2: The over-temperature test is performed on the sample cable insulation material placed inside the heating chamber. During the preparation of the sample cable, the cable insulation layer is cut into a suitable shape according to a predetermined thickness using a cable slicer, and the sample cable is rinsed and dried. Step 5.3: After the temperature control program of the heating chamber is completed, close the air inlet valve of the heating chamber, the pressure regulating valve of the heating chamber, the nitrogen generator and the air compressor, open the chamber door, take out the sample cable insulation material that has undergone the overheating test and seal it to obtain the cable insulation material that has undergone short-term overheating in the fire.

6. A device for preparing cable insulation material by simulating short-term overheating during a fire, characterized in that, include: A module is established to create a multi-physics coupled cable tunnel fire simulation model based on 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 a specific number of layers of the cable support and the target cable is placed there. The simulation test module is used to conduct fire simulation tests 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 plot 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 it takes for the temperature of the fire simulation test to reach the trigger temperature of the fire extinguishing bomb, the time for the fire extinguishing bomb to be delayed in triggering, 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 it takes for the temperature of the insulation layer of the target cable to drop to a preset temperature. The over-temperature test platform construction module is used to build an over-temperature test platform based on the cable tunnel fire simulation model. The over-temperature test platform includes a high-temperature treatment device, a vacuum pump, an inert gas generator, and an air compressor. The high-temperature treatment device is a heating box with automatic temperature control function, the vacuum pump is a vacuum pump, and the inert gas generator is a nitrogen generator. The setting module is used to set the high-temperature processing equipment of the over-temperature test platform with respect to the simulated temperature curve f. m The overtemperature test temperature curve where the error of (t) is within the predetermined error range; The over-temperature test module is used to conduct an over-temperature test on the sample cable insulation material according to the over-temperature test temperature curve, so as to obtain the cable insulation material that has experienced short-term over-temperature during a fire. The setting module is further configured to select n temperature points on the simulated temperature curve fm(t) of the insulation layer of the target cable as n temperature points of the heating box, and draw a dotted line graph as the preset temperature curve gm(t) of the heating box; compare the preset temperature curve gm(t) of the heating box with the simulated temperature curve fm(t), determine the error between the time interval corresponding to every two temperature points of the preset temperature curve gm(t) and the time interval corresponding to the same two temperature points of the simulated temperature curve fm(t); if the absolute value of the relative error of a point tx within the time interval [tk, tk+1] is greater than the predetermined error value Ea, then the time interval [tk, tk+1] is divided into two equal segments, and the time interval [tk, The temperature point corresponding to the center point of tk+1] is used as the new temperature point. The above steps are repeated until the error value of all time periods is less than the predetermined error value Ea, generating the updated temperature curve of the heating chamber. The power supply of each device of the over-temperature test platform is turned on, and the heating chamber is evacuated to a vacuum state using the vacuum pump. The heating chamber is started, and according to the updated temperature curve, the heating chamber is heated and cooled down. The actual temperature curve h(t) of the heating chamber is plotted. The actual temperature curve h(t) is compared with the simulated temperature curve fm. (t) is compared to determine the error value between the actual temperature curve h(t) and the simulated temperature curve fm(t). If the error value at time point ty is greater than the predetermined error value Eb, the heating program, cooling program, flow valve of the heating chamber, or flow valve of the nitrogen generator are adjusted to reduce the error value at time point ty. The above steps are repeated until the error value between the actual temperature curve h(t) and the simulated temperature curve fm(t) at each time point is less than the predetermined error value Eb, thus obtaining the overtemperature test temperature curve.

7. A non-volatile storage medium, characterized in that, The non-volatile storage medium stores multiple instructions, which are adapted to be loaded and executed by a processor as described in any one of claims 1 to 5, a method for preparing cable insulation material simulating short-term overheating during a fire.

8. 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 cause the one or more processors to implement a method for preparing cable insulation material simulating short-term overheating in a fire, as described in any one of claims 1 to 5.

9. A computer program product comprising computer instructions, characterized in that, The computer instructions are executed by the processor according to any one of claims 1 to 5, a method for preparing cable insulation material for simulating short-term overheating during a fire.

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