采空区二氧化碳注入防火效能的数值模拟研究

Research on the Hazard Assessment of Fire Wind Pressure Based on Fluent

摘要: 为深入探讨液态二氧化碳注入对煤矿采空区火灾防控的实际效能，本研究借助计算流体动力学技术，构建耦合组分传输与多孔介质流动的三维瞬态数值模型。模拟采用Realizablek-ε湍流模型、压力基求解器及组分输运模型，刻画采空区O₂、N₂、CO₂的混合传输动态；计算域划分上覆岩层与采空区垮落带两大多孔介质区域，参照权威文献设定边界条件(进风口为指定速度与氧浓度的空气流，回风口为压力出口，CO₂注入源为233 K高纯度质量流量源)。通过瞬态求解器捕捉温度场与气体组分场的动态演变，结果显示：CO₂注入可显著驱替稀释采空区氧气，形成明显缺氧区域；通过与程卫民、李宗翔文献数据对比，本模型模拟的氧浓度分布、CO₂扩散范围及降温幅度与文献结论偏差小于5%，验证了模型可靠性。进一步参数化研究表明，释放口埋深40~60 m、进风巷风速0.5 m/s、CO₂压注流量5 kg/s为最佳工况，此时有效惰化区体积达14200 m³，平均氧浓度降至3.2%，降温区域覆盖氧化带核心范围。本研究为定量评估CO₂防火灭火技术效能提供理论支撑，为采空区火灾防控奠定数值基础。

Abstract: To deeply explore the practical efficacy of liquid carbon dioxide (CO₂) injection in fire prevention and control of coal mine goafs, this study constructed a three-dimensional transient numerical model coupling component transport and porous media flow using computational fluid dynamics (CFD) technology. The simulation adopted the Realizable k-ε turbulence model, pressure-based solver, and component transport model to characterize the mixing and transport dynamics of O₂, N₂, and CO₂ in the goaf. The computational domain was divided into two porous media regions: the overlying strata and the goaf caving zone, with boundary conditions set with reference to authoritative literature (the air inlet was an air flow with specified velocity and oxygen concentration, the return air outlet was a pressure outlet, and the CO₂ injection source was a high-purity mass flow source at 233 K). The transient solver was used to capture the dynamic evolution of the temperature field and gas component field. The results showed that CO₂ injection could significantly displace and dilute oxygen in the goaf, forming an obvious oxygen-deficient region. By comparing with the literature data of Cheng Weimin et al. and Li Zongxiang et al., the deviation between the oxygen concentration distribution, CO₂ diffusion range, and temperature drop amplitude simulated by this model and the literature conclusions was less than 5%, verifying the model’s reliability. Further parametric studies showed that the optimal working conditions were release port burial depth of 40~60 m, air inlet velocity of 0.5 m/s, and CO₂ injection flow rate of 5 kg/s. Under these conditions, the volume of the effective inerting zone reached 14200 m³, the average oxygen concentration dropped to 3.2%, and the cooling region covered the core range of the oxidation zone. This study provides theoretical support for the quantitative evaluation of CO₂ fire prevention and extinguishing technology and lays a numerical foundation for goaf fire prevention and control.