Research on safety of electromagnetic wave thermal effect in explosive environment of underground coal mine
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摘要: GB/T 3836.1—2021《爆炸性环境 第1部分：设备 通用要求》规定爆炸性环境中射频设备的阈功率不得大于6 W，该规定限制了大功率射频设备在煤矿井下的应用，而现有针对爆炸性环境电磁安全性的相关研究缺乏完善的理论分析和实验验证。针对上述问题，推导了电磁波热效应方程，分析得出影响电磁波耦合瓦斯和煤尘混合气体产生热能的可控参数为电磁波耦合时间、电场强度和电磁波频率。以GB/T 3836.1—2021中可能堆积煤尘的电气设备表面温度最高不能超过150 ℃的规定为依据，采用多物理场仿真软件COMSOL对不同发射功率的电磁波耦合瓦斯和煤尘混合气体的热效应安全性进行了仿真实验，结果表明：满足温度不超过150 ℃的电磁波热效应安全阈发射功率为16.48 W； 随着电磁波发射功率的增加，电磁波热效应安全时长（电磁波耦合瓦斯和煤尘混合气体产生的热能不会使环境温度超过150 ℃对应的时间段）逐渐减少，但只要在安全时长内，电磁波的发射功率不受限制。Abstract: GB/T 3836.1-2021 Explosive atmospheres-Part 1: Equipment-General requirements stipulates that the threshold power of RF equipment in explosive environments shall not exceed 6 W. This regulation limits the application of high-power RF equipment in coal mines. However, existing research on electromagnetic safety in explosive environments lacks comprehensive theoretical analysis and experimental verification. In order to solve the above problems, the electromagnetic wave thermal effect equation is derived. It is analyzed that the controllable parameters affecting the generation of thermal energy from the mixture of gas and coal dust coupled by electromagnetic waves are the electromagnetic wave coupling time, the electric field strength and the electromagnetic wave frequency. Based on the regulation in GB/T 3836.1-2021 that the maximum surface temperature of electrical equipment that may accumulate coal dust cannot exceed 150 ℃, simulation experiments are conducted using the multi physics field simulation software COMSOL to evaluate the thermal safety of gas and coal dust mixtures coupled with electromagnetic waves of different emission powers. The results show that the emission power that meets the safety threshold of electromagnetic wave thermal effect with a temperature not exceeding 150 ℃ is 16.48 W. With the increase of electromagnetic wave emission power, the safe duration of electromagnetic wave thermal effect (the corresponding time period that the thermal energy generated by the mixed gas of electromagnetic wave coupling gas and coal dust not causing the ambient temperature to exceed 150 ℃) gradually decreases. However, as long as the safe duration is maintained, the emission power of electromagnetic waves is not limited.
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Key words:
- underground coal mine /
- electromagnetic wave thermal effect /
- gas /
- threshold power /
- safety duration
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图 2 电磁波热效应安全阈发射功率仿真结果
Figure 2. Simulation results of safe threshold transmitting power of electromagnetic wave thermal effect
图 3 不同发射功率的电磁波热效应仿真结果
Figure 3. Simulation results of electromagnetic wave thermal effect with different transmission powers
表 1 仿真模型几何参数
Table 1. Geometric parameters of simulation model
参数 L1 W1 H1 L2 W2 H2 值/cm 30 70 70 30 60 60 
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表 4 瓦斯的热学性质参数
Table 4. Thermal property parameters of gas
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表 6 瓦斯和煤尘的电热学性质参数
Table 6. Electrothermal property parameters of gas and coal dust
参数 瓦斯 煤尘 电导率/（S·m−1） 1.1 2.6×10−3 介电常数/（F·m−1） 5.57 522 密度/（kg·m−3） — 1 846 导热系数/（W·m−1·K−1） 0.022 1.215 热膨胀系数/K−1 — 0.000 12 恒压热容/ （J·kg−1·K−1） 2570 1 200
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