埋地热油管道圆形边界处理方法的比较

Comparison of the Methods for Treating the Circlular Borders of Underground Heated Pipelines

研究热油管道停输再启动及间歇输送,首要的问题是计算管道周围土壤的非稳态温度场。在土壤温度场模型中,将土壤的半无限大区域转化成有限矩形区域,利用有限差分法进行离散化求解。对于埋地管道圆形边界的处理,可用阶梯形折线或方形边界来近似代替管道圆形边界;通过比较利用方形边界和折线边界计算所得的热流密度值(随埋深、半径、保温层厚度的变化),说明用方形边界代替管道圆形边界是可行的,并且可以简化埋地管道的传热计算。

To make research on the restart after shutdown and the intermittent transmission of a underground heated pipeline,the first thing to be done is to calculate the instable temperature field around the pepeline. In the mathematical model of the soil temperature field, half of the infinite area under the soil is transformed into a finite rectangular area. The finite difference theory is used for calculation of discretization. This finite difference method can use step-like broken lines and rectangular borderlines instead of circular borders as underground heated pipeline. A comparison of the thermal results of the two borders shows that it is feasible to use rectangular borderlines to replace circular ones. Thus it can simplify the calculation of heat transfer for the underground heated pipeline.