导线作为电力和信息传输的关键组件，被广泛应用于工业厂房、航空航天等领域。由于在高海拔区域、核电站、航空航天等场所环境压力与常压不同，会对导线的燃烧特性和火蔓延行为产生影响。鉴于此，本文选取PE与PVC导线为研究对象，研究两种导线的热解特性和在不同压力条件下的燃烧特性及火蔓延行为。

采用热重分析仪研究了不同氛围、升温速率下PE与PVC导线的热解特性。在氮气氛围下，PE与PVC导线的质量损失速率随着升温速率上升均向高温区位移。PE导线的热解过程表现为单一阶段特征，而PVC导线热解行为分为三个阶段。在空气氛围下，PE与PVC导线热解过程持续时间显著延长，PE导线的热解可分为两个阶段，PVC导线分为三个阶段。同一升温速率下，PVC导线先于PE导线发生分解。利用两种无模型函数法KAS方法和FWO方法计算得到PE和PVC导线不同转化率下的活化能分别为248.56、266.61 kJ/mol。

运用火焰传播量热仪和S65耐压燃烧室研究压力、辐射强度对PE与PVC导线燃烧行为的影响。随着辐射强度增强，导线点燃时间明显缩短，热释放速率有所降低，峰值时间延迟，辐射热流以及质量损失速率均显著提升，O₂消耗量与CO、CO₂生成量同步增加。同一辐射强度条件下，随着压力的增加，导线的点燃温度及燃烧时的CO含量降低，剩余O₂百分含量及热通量增加，质量损失曲线提前，燃烧特性参数呈现增强态势。

借助S65耐压燃烧室研究压力、氧浓度对PE与PVC导线火蔓延特性的影响。随着压力升高或氧浓度增大，导线的火焰宽度减小，火焰高度增加，火蔓延速率和质量损失速率加快。当氧浓度为21%时，PE导线在40~80 kPa压力范围出现熔融滴落现象，火焰形态稳定，当压力超过80 kPa时，熔融滴落现象消失。在氧浓度为30%时，压力超过60 kPa则无滴落现象。相比之下，PVC导线没有熔融滴落现象，但伴随着“跳跃火焰”现象，其火蔓延特性参数随压力和氧浓度变化的趋势与PE导线相似。

采用VOF方法和焓-多孔介质法来模拟PE在铜板上的熔化过程和动态滴落运动，得到了PE熔化滴落过程中速度、压力、温度随时间分布。液滴在4.4 s时出现液滴，生成的熔融PE液滴在重力作用下与主体分离，此时达到最大速度约22 cm/s，PE液滴下降时周围的气流呈螺旋运动，温度场倾向于向周围空间扩散。研究内容有助于深入理解导线在不同环境条件下的燃烧特性和火蔓延行为，为火灾安全领域的研究和实践提供理论依据。

Conductors are widely used in industrial plants, aerospace and other areas as key components for power and information transmission. As the environmental pressure in high-altitude areas, nuclear power plants, aerospace and other places is different from atmospheric pressure, it will have an impact on the combustion characteristics and fire spread behavior of the wire. In view of this, this paper selects PE and PVC wires as the object to study the pyrolysis characteristics, combustion process and fire spread behavior of the two wires under different pressure conditions.

The pyrolysis characteristics of PE and PVC wires under different atmospheres and heating rates were studied using a thermogravimetric analyzer. In a nitrogen atmosphere, the mass loss rate of PE and PVC wires shifts towards the high-temperature zone as the heating rate increases. The pyrolysis process of PE wires exhibits a single stage characteristic, while the pyrolysis behavior of PVC wires is divided into three stages. In an air atmosphere, the duration of the pyrolysis process of PE and PVC wires is significantly prolonged. The pyrolysis of PE wires can be divided into two stages, while PVC wires can be divided into three stages. At the same heating rate, PVC wires decompose before PE wires. The activation energies of PE and PVC wires at different conversion rates were calculated using two model free function methods, KAS method and FWO method, and were 248.56 and 266.61 kJ/mol, respectively.

Using a Fire Propagation Apparatus and S65 pressure resistant combustion chamber, the effects of pressure and radiation intensity on the combustion behavior of PE and PVC wires were studied. As the radiation intensity increases, the ignition time of the wire is significantly shortened, the heat release rate is reduced, the peak time is delayed, the radiation heat flux and mass loss rate are significantly increased, and the consumption of O₂ increases synchronously with the generation of CO and CO_2. Under the same radiation intensity conditions, as the pressure increases, the ignition temperature of the wire and the CO content during combustion decrease, while the remaining O₂ percentage and heat flux increase. The mass loss curve advances, and the combustion characteristic parameters show an enhanced trend.

Using S65 pressure resistant combustion chamber to study the effects of pressure and oxygen concentration on the fire propagation characteristics of PE and PVC wires. As the pressure or oxygen concentration increases, the flame width of the wire decreases, the flame height increases, and the fire propagation rate and mass loss rate accelerate. When the oxygen concentration is 21%, the PE wire shows melting and dripping phenomenon in the pressure range of 40~80 kPa, and the flame shape is stable. When the pressure exceeds 80 kPa, the melting and dripping phenomenon disappears. When the oxygen concentration is 30% and the pressure exceeds 60 kPa, there is no dripping phenomenon. In contrast, PVC wires do not exhibit melting and dripping phenomena, but are accompanied by the phenomenon of "jumping flames". The trend of their fire propagation characteristic parameters with pressure and oxygen concentration changes is similar to that of PE wires.

The VOF method and Enthalpy-Porosity method were used to simulate the melting process and dynamic drop motion of PE on copper plate, and the velocity, pressure, and temperature distribution with time were obtained during the PE melting drop process. The molten PE drop generated at 4.4 s separates from the main body by gravity and appears as a droplet, at which time it reaches a maximum velocity of about 22 cm/s. The airflow around the PE drop falls in a helical motion, and the temperature field tends to spread out to the surrounding space. The research content helps to deepen the understanding of the combustion characteristics and fire spread behavior of wires under different environmental conditions, providing theoretical basis for research and practice in the field of fire safety.

[1] 贺胜, 疏学明, 胡俊, 等. 基于消防大数据的电气火灾风险预测预警方法[J]. 清华大学学报, 2024, 64(3):478-491.

[2] Longhua Hu, Keke Zhu, Yong Lu, et al. An experimental study on flame spread over electrical wire with high conductivity copper core and controlling heat transfer mechanism under sub-atmospheric pressur[J]. International Journal of Thermal Sciences. 2019, 141:141-149.

[3] 王振宇. 电气火灾短路故障点与起火点分析[J]. 数字通信世界, 2021(06): 263-264.

[4] 蒋帅, 贾佳, 武红梅. 典型核电站厂房内电缆桥架火蔓延特性的全尺寸实验分析[J].船海工程, 2020, 49(6):36-38.

[5] Huang X, Nakamura Y. A review of fundamental combustion phenomena in wire fires[J]. Fire Technology, 2020, 56(1): 315-360.

[6] 李建波, 梁招瑞, 宋永军, 等. 某核电机组安全壳打压试验期间安全壳外加应变计数据分析研究[J]. 核技术, 2019, 42(12): 75-84.

[7] 贺元骅, 张政, 伍毅. 低压环境下航空电缆材料燃烧特性的研究[J]. 塑料科技, 2020, 48(1): 71-74.

[8] 丁超, 李雨遥, 何凌峰, 等. 不同环境压力与倾角下电缆火燃烧特性研究[J]. 消防科学与技术, 2023, 42(9): 1197-1201.

[9] Seo Hyun Jeong, Kim Nam Kyun, Lee Min Chul, et al. Investigation into the toxicity of combustion products for CR/EPR cables based on aging period[J]. Journal of Mechanical Science & Technology, 2020, 34(4): 1785-1794.

[10] Huang X, Zhu H, Peng L, et al. Burning behavior of cable tray located on a wall with different cable arrangements[J]. Fire Mater. 2019, 43(1): 64-73.

[11] Jianping Zhang, Delichatsios Michael, Colobert Matthieu. Assessment of Fire Dynamics Simulator for Heat Flux and Flame Heights Predictions from Fires in SBI Tests[J]. Fire Technology, 2010, 46(2): 291-306.

[12] Iglesias A, del Castillo MD, Serrano JI, et al. A Decision Support System Applied to Emergency Situations in Real Time[J]. REVISTA IBEROAMERICANA DE AUTOMATICA E INFORMATICA INDUSTRIAL, 2011, 8(1): 80.

[13] Van Hees P, Axelsson J, Green A M, et al. Mathematical modelling of fire development in cable installations[J]. Fire and materials, 2001, 25(4): 169-178.

[14] Osorio A.F, Mizutani K, Fernandez-Pello C, et al. Microgravity flammability limits of ETFE insulated wires exposed to external radiation[J]. Proceedings of the Combustion Institute, 2015, 35(3): 2683-2689.

[15] Miyamoto K, Huang X, Hashimoto N, et al. Limiting oxygen concentration (LOC) of burning polyethylene insulated wires under external radiation[J]. Fire Safety Journal, 2016, 86: 32-40.

[16] Ferng Y, Liu C. Investigating the burning characteristics of electric cables used in the nuclear power plant by way of 3-D transient FDS code[J]. Nuclear Engineering and Design, 2011, 241 (1): 88-94.

[17] Courty L, Garo J. External heating of electrical cables and auto-ignition investigation[J]. Journal of Hazardous Materials, 2017, 321: 528-536.

[18] Fontaine G, Ngohang F-E, Gay L, et al. Investigation of the Contribution to Fire of Electrical Cable by a Revisited Mass Loss Cone[J]. Fire Science and Technology 2015, 2017: 687-693.

[19] Zavaleta P, Audouin L. Cable tray fire tests in a confined and mechanically ventilated facility[J]. Fire and materials, 2018, 42(1): 28-43.

[20] Emanuelsson V, Simonson M, Gevert T. The effect of accelerated ageing of build wires[J]. Fire and materials, 2007, 31(5): 311-326.

[21] Meinier R, Sonnier R, Zavaleta P, et al. Fire behavior of halogen-free flame retardant electrical cable with the cone calorimeter[J]. J Hazard Mater, 2018, 342: 306-316.

[22] 文虎, 赵向涛, 王伟峰, 等. 导线起火和燃烧特性研究进展[J]. 消防科学与技术. 2021, 40(4): 471-476.

[23] 王之琦, 何豪, 朱家哲, 等. 火场条件下常用电缆产烟特征及烟气毒性分析[J]. 安全与环境工程, 2023, 30(6): 17-22.

[24] 吴金. 电缆烟密度试验主要影响因素及控制措施的研究[J]. 电工技术, 2023, (13): 93-95.

[25] 杨玲, 刘志敏. 羟基锡酸锌阻燃聚氯乙烯电缆材料及其潜在火灾危险性评价[J]. 火灾科学. 2010, 19(1): 27-32.

[26] 龚泰, 黄鑫炎, 谢启源. 基于桶式环形加热的阻燃电缆细观竖直燃烧特性研究实验平台的设计[J]. 火灾科学, 2017, 26(04): 226-231.

[27] Gong T, Xie Q, Huang X. Fire behaviors of flame-retardant cables part Ⅰ: Decomposition, swelling and spontaneous ignition[J]. Fire Safe Journal. 2018, 95: 113-121.

[28] Zhang B, Zhang J, Li Q, et al. Effects of Insulating Material Ageing on Ignition Time and Heat Release Rate of the Flame Retardant Cables[J]. Procedia Engineering. 2018, 211: 972-978.

[29] 付强, 张和平, 龚伦伦, 等. 基于CONE和MCC的典型电缆燃烧性能研究[J]. 火灾科学, 2012, 21(01): 13-20.

[30] 毛青龙, 朱鹏, 赵彦丽, 等. 聚氯乙烯材料的燃烧特性研究[J]. 塑料科技, 2024, 52(03): 49-54.

[31] 赵彦丽. 压力和氧浓度对PE导线火蔓延及燃烧特性影响研究[D]. 合肥: 中国科学技术大学, 2018.

[32] 张政, 贺元骅, 王明武, 等. 低压环境下航空电缆和普通电缆燃烧性能[J]. 消防科学与技术. 2019, 38(7): 910-913.

[33] 贺元骅, 阳邦, 张政, 等. 低压环境下航空电缆点燃性能及烟气特性[J]. 科学技术与工程. 2021, 21(6): 2545-2549.

[34] Bakhman N, Aldabaev L, Kondrikov B, et al. Burning of polymeric coatings on copper wires and glass threads: I. Flame propagation velocity[J]. Combust Flame, 1981, 41(1): 17-34.

[35] Bakhman N, Aldabaev L, Kondrikov B, et al. Burning of polymeric coatings on copper wires and glass threads: П. Critical conditions of burning[J]. Combustion and Flame, 1981, 41(6): 35-43.

[36] Nakamura Y, Yoshimura N, Ito H, et al, Flame spread over electric wire in sub-atmospheric pressure[J]. Proceeding of the Combustion Institute. 2009. 32(2): 2559-2566.

[37] Nakamura Y, Azumaya K, Iwakami J, et al. Scale Modeling of Flame Spread Over PE-Coated Electric Wires[J]. Progress in Scale Modeling, 2015, 2: 275-292.

[38] Shuhei Takahashi, Hiroyuki Takeuchi, Hiroyuki Ito, et al. Study on unsteady molten insulation volume change during flame spreading over wire insulation in microgravity[J]. Proceedings of the Combustion Institute, 2013, 34(2): 2657-2664.

[39] Huang X Y. Critical drip size and blue flame shedding of dripping ignition in fire[J]. Scientific reports, 2018, 8(1): 16528.

[40] Kobayashi Y, Huang X Y, Nakaya S, et al. Flame spread over horizontal and vertical wires: The role of dripping and core[J]. Fire Safe Journal, 2017, 91: 112-122.

[41] Hu L, Lu Y, Yoshioka K, et al. Limiting oxygen concentration for extinction of upward spreading flames over inclined thin polyethylene-insulated NiCr electrical wires with opposed-flow under normal-and micro-gravity [J]. Proceedings of Combustion Institute, 2017, 36(2): 3045-3053.

[42] Lu Y, Huang X, Hu L, et al. The interaction between fuel inclination and horizontal wind: Experimental study using thin wire[J]. Proceedings of Combustion Institute. 2019, 37(3): 3809-3816.

[43] 夏云春. 电缆束分布特性对燃烧火蔓延速度的影响[J]. 青岛科技大学学报. 2011, 32(2): 165-171.

[44] 祝现礼, 孙绪绪. 金属芯热传导效应对电缆线水平火蔓延的影响[J]. 消防科学与技术, 2023, 42(8): 1057-1062.

[45] Zhang Y, Fang J, Wang J, et al. The effects of angular orientation and ultraviolet aging on ETFE wire flame spread[J]. Fire and materials, 2019, 43(4): 393-400.

[46] Nakamura Y, Yoshimura N, Matsumura T, et al. 2008. Opposed-wind effect on flame spread of electric wire in sub-atmospheric pressure[J]. Journal of thermal science and technology. 3(3): 430-441.

[47] Hu L H, Zhang Y S, Yoshioka K, et al. Flame spread over electric wire with high thermal conductivity metal core at different inclinations [J]. Proceedings of the Combustion Institute, 2015, 35(3): 2607-2614.

[48] 薛岩, 方俊, 王静舞. 低压下聚乙烯绝缘层导线火蔓延熔融滴落实验分析[J]. 火灾科学, 2017, 4: 191-197.

[49] Huang X Y, Nakamura Y, Williams F A. Ignition-to-spread transition of externally heated electrical wire[J]. Proceedings of the Combustion Institute, 2013, 34(2): 2505-2512.

[50] Guibaud A, Consalvi J L, Orlac'h J M, et al. Soot Production and Radiative Heat Transfer in Opposed Flame Spread over a Polyethylene Insulated Wire in Microgravity[J]. Fire Technology, 2020, 56(1): 287-314.

[51] Zhao Y L, Chen J, Chen X. et al. Pressure effect on flame spread over polyethylene insulated copper core wire[J]. Applied Thermal Engineering, 2017, 123: 1042-1049.

[52] Richter F, Rein G. A multiscale model of wood pyrolysis in fire to study the roles of chemistry and heat transfer at the mesoscale [J]. Combust Flame,2020, 216: 316-325.

[53] Jiang L, Xiao H-H, He J-J, et al. Application of genetic algorithm to pyrolysis of typical polymers[J]. Fuel Process Technol, 2015, 138: 48-55.

[54] John, E, White, et al. Biomass pyrolysis kinetics: A comparative critical review with relevant agricultural residue case studies[J]. Journal of analytical & applied pyrolysis, 2011,91(1): 1-33.

[55] Vyazovkin S, Burnham A K, Criado J M, et al. ICTAC Kinetics Committee recommendations for performing kinetic computations on thermal analysis data [J]. Thermochimica Acta, 2011, 520(2): 1-19.

[56] Wang C, Liu H, Zhang J, et al. Thermal Degradation of Flame-retarded high-voltage Cable sheath and Insulation via TG-FTIR[J]. J Anal Appl Pyrolysis, 2018,134: 167-175.

[57] Babrauskas V. Ignition Handbook-Principles and applications to fire safety engineering, fire investigation, risk management and forensic science[J]. 2020,14(3): 229-232.

[58] Samuel S, Dannaway. SFPE Handbook of Fire Protection Engineering[J]. Plumbing engineer, 2017, 45(6): 36.

[59] Malkappa Kuruma, Bandyopadhyay Jayita, Ray Suprakas Sinha. Thermal Degradation Characteristic and Flame Retardancy of Polylactide-Based Nanobiocomposites[J]. Molecules, 2018, 23(10): 2648.

[60] 刘全义, 孙中正, 吕志豪, 等. 不同压力条件下典型机舱材料燃烧特征的实验研究[J]. 清华大学学报, 2019, 59(6): 432-438.

[61] Fereres S, Fermandez P C, Urban D L, et al. Identifying the roles of reduced gravity and pressure on the piloted ignition of solid combustibles[J]. Combustion and Flame, 2015, 162(4): 1136-1143.

[62] Jianfeng Zhou, Genserik Reniers, Valerio Cozzani. Improved probit models to assess equipment failure caused by domino effect accounting for dynamic and synergistic effects of multiple fires[J]. Process Safety and Environmental Protection, 2021, 154: 306-314.

[63] 冯瑞, 田润和, 陈科位, 等. 低气压环境对固体燃烧特性影响的实验研究[J]. 清华大学学报, 2019, 59(02): 111-121.

[64] Huang X Y, Nakamura Y. A Review of Fundamental Combustion Phenomena in Wire Fires[J]. Fire Technology, 2020, 56(1): 315-360.

[65] 王兴华, 王彦峰, 雷翔胜, 等. 电缆用高阻燃耐热软质PVC的制备及性能研究[J]. 塑料科技, 2022, 50(1): 36-39.

[66] Jiang L, Xiao H H, An W G, et al. Correlation study between flammability and the width of organic thermal insulation materials for building exterior walls [J]. Energy and Buildings, 2014, 82: 243-249.

[67] Li Z, Liu N, Xie X, et al. Heat transfer blockage of small-scale PMMA flame under exterior heat radiation [J]. Int J Therm Sci, 2017, 122: 26-32.

[68] McAllister S, Fernandez-Pello C, Urban D, et al. The combined effect of pressure and oxygen concentration on piloted ignition of a solid combustible[J]. Combustion and flame, 2010, 157(09): 1753-1759.

[69] Tu R, Zeng Y, Fang J, et al. The influence of low air pressure on horizontal flame spread over flexible polyurethane foam and correlative smoke productions[J]. Applied Thermal Engineering, 2016, 94: 133-140.

[70] He H, Zhang, QX, Tu R, Zhao LY, Liu J, Zhang YM. Molten thermoplastic dripping behavior induced by flame spread over wire insulation under overload currents [J]. Journal of Hazardous Materials, 2016, 320: 628-634.

[71] 朱宗林, 陆凯华, 贾欣苗, 等. 不同倾角和间距条件下平行双导线火蔓延实验研究[J]. 安全与环境工程, 2023, 30(2): 53-60.

[72] Ma Y, Zhang X, Lu Y, et al. Effect of transverse flow on flame spread and extinction over polyethylene-insulated wires[J]. Proceedings of the Combustion Institute, 2021, 38(3): 4727-4735.

[73] Yuxuan M, Xiaolei Z, Yong L, et al. Effect of transverse flow on flame spread and extinction over polyethylene-insulated wires[J]. Proceedings of the Combustion Institute, 2020, 38(3): 4727-4735.

[74] Kim Y, Hossain A, Nakamura Y. Numerical study of melting of a phase change material (PCM) enhanced by deformation of a liquid–gas interface[J]. International Journal of Heat and Mass Transfer, 2013, 63: 101-112.

[75] 邱勇军, 朱恂, 王宏, 等. 熔渣颗粒空冷相变换热的三维数值模拟[J]. 化工学报, 2014, 65(S1): 340-345.

[76] QIAO MengWen, XING ZeRong, FU Jun-Heng, et al. Multiphase flow physics of room temperature liquid metals and its applications[J]. Science China, 2023, 66(6): 1483-1510.

[77] Kim Y, Hossain A, Nakamura Y. Numerical modeling of melting and dripping process of polymeric material subjected to moving heat flux: Prediction of drop time[J]. Proceedings of the Combustion Institute, 2015, 35(3): 2555-2562.

[78] Shmueli H, Ziskind G, Letan R. Melting in a vertical cylindrical tube: Numerical investigation and comparison with experiments[J]. International Journal of Heat and Mass Transfer, 2010, 53(19-20): 4082-4091.

[79] Unnikrishnan Karthamadathil Sasidharan, Rohinikumar Bandaru. Thermal management of photovoltaic panel with nano-enhanced phase change material at different inclinations[J]. Environmental Science and Pollution Research, 2022, 29(23): 34759-34775.

[80] Liu ZY, Yao YP, Wu HY. Numerical modeling for solid–liquid phase change phenomena in porous media: Shell-and-tube type latent heat thermal energy storage[J].Applied Energy, 2013, 112: 1222-1232.

[81] Valdes-Parada F J, Ochoa-Tapia J A, Alvarez-Ramirez J. Validity of the permeability Carman-Kozeny equation: A volume averaging approach[J]. Physica A, 2009, 388(6): 789-798.

[82] Wang, Q; Li, BK. Numerical investigation on the effect of fill ratio on macrosegregation in electroslag remelting ingot[J]. Applied Thermal Engineering, 2015, 91: 116-125.

[83] Vachaparambil, Kurian J.; Einarsrud, et al. Comparison of Surface Tension Models for the Volume of Fluid Method[J]. Processes, 2019, 7(8): 542.

[84] Kim Y. A multiphase-based numerical study on time-dependent melting, deforming and dripping process of Phase Change Material induced by external heat source[D]. Hokkaido: Hokkaido University, 2013.

[85] 付涛涛, 朱春英, 马友光. 微通道内卫星液滴生成机理与惯性分离机制[J]. 化工学报, 2020, 71(2): 451-458.