含内热源松散煤体热质耦合数值模拟研究
发布时间：2018-07-14 07:53
【摘要】：露天自然堆积煤堆的自燃发火是煤矿安全生产的主要威胁之一,由于露天煤堆面积大,松散煤的堆放形态各异,自燃发火的时间和位置随机因素大,而研究松散煤体内部热质耦合的一些规律对预防上述矿区位置松散煤堆的自燃发火有一定帮助。本文根据含内热源松散煤体物理模型建立松散煤多孔介质内部热质耦合数学模型,运用适体坐标系中的代数法对不规则的梯形物理求解域进行网格划分,将物理求解与网格节点数据转化到矩形计算求解域,通过C#编写网格生成算法和Simple算法对建立的数学模型进行求解。根据求出的数值解分析研究松散煤体内部温度和湿度的变化,松散煤体孔隙中气相在内部热源作用下的流动情况,在热源作用下松散煤体孔隙中非饱和液相水随时间的蒸发,以及气相的自然对流等情况。根据对数学模型数值解的分析,结果表明,含非饱和液相水的松散煤体在内热源作用下,以热源为中心的温度和水蒸气相体积分数纵向呈椭圆形分布规律,即纵向温度变化和水蒸气相体积分数均比其在横向的变化要快,这种现象在内部热源控制温度较低时变化不明显,但会随着内热源控制温度的升高而愈加显著,在内部热源控制温度由50℃到350℃的变化过程中,在热源纵向0.4m和横向0.3m处的最大温度差超过10℃,且在热源附近气相流速的最大值已达到10-3m/s这一量级,热源附近存在明显的自然对流。同时,将数值解与在fluent中得出结果进行对比结果基本吻合。通过综合分析松散煤体内部在温度不断升高的热源的作用下,随着液相水的蒸发、气相的质扩散和热弥散等因素的影响,得出在热源附近松散煤体的温度呈椭圆形分布规律,以及椭圆形态随时间和热源温度升高的变化规律,为露天煤堆的高度控制和内部温度的监控提供一定的指导意义。
[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，
本文编号：2120974
[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，
本文编号：2120974
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