In this study, the theoretical approach and numerical modelling of coal spontaneous combustion were investigated considering the aging effect. Numerical simulations of three-dimensional coal piles in cubic wire-mesh baskets (WMBs) were performed using ANSYS FLUENT. A theoretical heat generation model was constructed that incorporated aging effect (using a decay-power factor, γ), equivalent oxidation exposure time (EOE-time) theory, and moisture evaporation. The results from this model were compared with those obtained from the conventional Arrhenius equation, which does not take aging effect into account. The γ value required to accurately express the aging effect in conjunction with EOE-time theory was determined to be 4 × 10−5 s−1 for the low-rank coal used in this work. This value was obtained by comparing simulated and measured coal temperature-time curves in WMBs. A moisture evaporation model that included an estimated evaporation heat rate was applied, based on the difference between coal moisture ratio and air relative humidity. These models were employed to simulate the self-ignition behaviour of coal piles and to explore the different heating processes of wet and dry coals. Finally, the relationships between pile volume and both critical self-ignition temperature and critical lead time were presented for industrial management of coal piles.

中文翻译：

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考虑老化效应的煤堆自热行为数值模拟

在这项研究中，考虑了老化效应，研究了煤自燃的理论方法和数值模拟。使用 ANSYS FLUENT 对立方丝网筐 (WMB) 中的三维煤堆进行数值模拟。构建了一个理论发热模型，该模型结合了老化效应（使用衰减功率因数，γ）、等效氧化暴露时间（EOE 时间）理论和水分蒸发。将该模型的结果与未考虑老化效应的常规 Arrhenius 方程所得结果进行比较。对于这项工作中使用的低阶煤，结合 EOE 时间理论准确表达老化效应所需的 γ 值被确定为 4 × 10-5 s-1。该值是通过比较 WMB 中模拟和实测煤温-时间曲线获得的。基于煤水分比和空气相对湿度之间的差异，应用了包括估计蒸发热率的水分蒸发模型。这些模型被用来模拟煤堆的自燃行为，并探索干煤和湿煤的不同加热过程。最后，提出了用于煤堆工业管理的堆体积与临界自燃温度和临界提前期之间的关系。这些模型被用来模拟煤堆的自燃行为，并探索干煤和湿煤的不同加热过程。最后，提出了用于煤堆工业管理的堆体积与临界自燃温度和临界提前期之间的关系。这些模型被用来模拟煤堆的自燃行为，并探索干煤和湿煤的不同加热过程。最后，提出了用于煤堆工业管理的堆体积与临界自燃温度和临界提前期之间的关系。