玻璃池窑中流动与传热的二维数学模型

Two-Dimensional Mathematical Model of the Flow and Heat Transfer in Glass Tank Furnace

在理解熔体流动和传热机理的基础上,确立了非电热玻璃池窑中流动和传热的二维数学模型.高温下玻璃熔体物理性质的计算程式如下:根据Boussinesq近似,除浮力项外,在力距公式中密度被视为常数;以有效导热系数表示真实热导和辐射热导的综合作用.根据生产实际情况,确定边界条件;应用SIMPLE法在IBM-AT计算机上计算了窑内玻璃液的温度场和速度场.在求解方程时,应用"Line-by-line"求解法并采用了分块修正法以加速度收敛速度.选择数个方案,研究了池窑冷却部池深、窑底保温及出口流量变化等对池窑内玻璃液的温度场和速度场的影响.结果表明:减少池深可提高降温效果;窑底保温可增加玻璃液的循环流速,特别是逆流速度,从而提高了玻璃液的化学均匀性和温度均匀性;使窑内自然对流增强,远远大于作业流;随着出口流量的增大,冷却部玻璃液温度将逐渐增高.数学模拟计算的结果定量地显示了窑炉结构设计与作业制度的相对应关系.

A two dimensional mathematical model of the flow and heat transfer in a glass tank furnace without electric heating was set up based on an understanding of the mechanism of flow and heat transfer. The calculations of the physical properties of glass melt at high temperatures were formulated as follows: according to the Boussinesq approximation, the density was considered as a constant in the momentum equations except for the buoyancy term; the effective heat conductivity was used to express the total influence of both true thermal and radiative conductivties of glass. The boundary conditions were determined in accordance with the actual situation of production. The temperature and velocity profiles of glass melt in glass tank were computed in an IBM-AT computer by SIMPLE method and solved according to the 'Liue-by-line' method with 'block correction' method for faster convergence. Investigations on temperature field, velocity field and glass flow distribution in glass tank furnace were made with a variation of conditioning zone, the temperature of siege and the flow of glass. The conclusions are: 1. Reducing the depth of conditioning zone may benefit cooling in that area. 2. Rising the siege temperature will increase the velocity of glass circulation, particularly of the return flow, which will benefit the chemi- eal and thermal homogeneities of glass melt, as a result, the natural convection flow may surpass the operation flow. 3. anincrease of the output flow will raise the temperature of glass melt in the conditioning zone. The resuts of the simulative calculative quantitatively shows the close correlations of the construction design of the tank furnace with a practical operation scheme of glass melting.