【摘要】：露天自然堆積煤堆的自燃發(fā)火是煤礦安全生產(chǎn)的主要威脅之一,由于露天煤堆面積大,松散煤的堆放形態(tài)各異,自燃發(fā)火的時間和位置隨機(jī)因素大,而研究松散煤體內(nèi)部熱質(zhì)耦合的一些規(guī)律對預(yù)防上述礦區(qū)位置松散煤堆的自燃發(fā)火有一定幫助。本文根據(jù)含內(nèi)熱源松散煤體物理模型建立松散煤多孔介質(zhì)內(nèi)部熱質(zhì)耦合數(shù)學(xué)模型,運用適體坐標(biāo)系中的代數(shù)法對不規(guī)則的梯形物理求解域進(jìn)行網(wǎng)格劃分,將物理求解與網(wǎng)格節(jié)點數(shù)據(jù)轉(zhuǎn)化到矩形計算求解域,通過C#編寫網(wǎng)格生成算法和Simple算法對建立的數(shù)學(xué)模型進(jìn)行求解。根據(jù)求出的數(shù)值解分析研究松散煤體內(nèi)部溫度和濕度的變化,松散煤體孔隙中氣相在內(nèi)部熱源作用下的流動情況,在熱源作用下松散煤體孔隙中非飽和液相水隨時間的蒸發(fā),以及氣相的自然對流等情況。根據(jù)對數(shù)學(xué)模型數(shù)值解的分析,結(jié)果表明,含非飽和液相水的松散煤體在內(nèi)熱源作用下,以熱源為中心的溫度和水蒸氣相體積分?jǐn)?shù)縱向呈橢圓形分布規(guī)律,即縱向溫度變化和水蒸氣相體積分?jǐn)?shù)均比其在橫向的變化要快,這種現(xiàn)象在內(nèi)部熱源控制溫度較低時變化不明顯,但會隨著內(nèi)熱源控制溫度的升高而愈加顯著,在內(nèi)部熱源控制溫度由50℃到350℃的變化過程中,在熱源縱向0.4m和橫向0.3m處的最大溫度差超過10℃,且在熱源附近氣相流速的最大值已達(dá)到10-3m/s這一量級,熱源附近存在明顯的自然對流。同時,將數(shù)值解與在fluent中得出結(jié)果進(jìn)行對比結(jié)果基本吻合。通過綜合分析松散煤體內(nèi)部在溫度不斷升高的熱源的作用下,隨著液相水的蒸發(fā)、氣相的質(zhì)擴(kuò)散和熱彌散等因素的影響,得出在熱源附近松散煤體的溫度呈橢圓形分布規(guī)律,以及橢圓形態(tài)隨時間和熱源溫度升高的變化規(guī)律,為露天煤堆的高度控制和內(nèi)部溫度的監(jiān)控提供一定的指導(dǎo)意義。
[Abstract]:The spontaneous combustion of natural pile of coal in the open air is one of the main threats to the safe production of coal mine. Due to the large area of open pit coal pile, the stacking of loose coal varies in shape, and the random factors of time and location of spontaneous combustion are large, It is helpful to study some rules of heat and mass coupling in loose coal body to prevent spontaneous combustion of loose coal pile in the above mining area. In this paper, based on the physical model of loose coal body with internal heat source, the mathematical model of heat and mass coupling in porous medium of loose coal is established, and the irregular trapezoidal physical solution domain is meshed by using algebraic method in body-fitted coordinate system. The physical solution and grid node data are transformed into rectangular computational solution domain, and the mathematical model is solved by C # programming mesh generation algorithm and simple algorithm. According to the calculated numerical solution, the variation of temperature and humidity in loose coal body is studied. The flow of gas phase in loose coal pore under the action of internal heat source and the evaporation of unsaturated liquid water in the pore of loose coal body with time under the action of heat source are studied. And the natural convection of the gas phase. According to the analysis of the numerical solution of the mathematical model, the results show that under the action of the internal heat source of loose coal body containing unsaturated liquid water, the temperature and the volume fraction of water vapor phase at the center of the heat source show the law of longitudinal elliptical distribution. That is to say, the variation of longitudinal temperature and the volume fraction of water vapor phase are faster than that of the horizontal phase. This phenomenon is not obvious when the internal heat source control temperature is lower, but it will become more obvious with the increase of the internal heat source control temperature. In the process of internal heat source controlling temperature changing from 50 鈩，

本文編號：2120974