季节冻土区埋地管道水温的变化规律及其影响因素分析

Variations and influencing factors of the water temperature within the pipe buried in seasonally frozen ground areas

埋地管道是减少寒冷地区冬季冻害的常用铺设方式,深入认识埋地管道的水温变化规律可以为减小管道埋设深度、降低管道冻害提供理论依据,对当前季节冻土区农牧民集中式供水工程的推进具有指导意义.采用仿三维数值方法建立了管道水温的计算模型,讨论了含水量、地表温度、管道埋深等6个主要因素对埋地管道最不利水温的影响.分析结果表明,无论上述因素如何变化,管道最不利水温均随输送距离的增加而下降.首先,随着含水量的增加、地表温度的升高以及管道埋深的加深,管道的降温速率不断减小并具有先快后慢的特点;其次,随着管径的减小、流速的降低,管道降温速率增大,且降温速率和流速之间具有近似的倒数关系.另外,随着入口温度的升高,管道降温速率将呈指数形式不断增加.

To bury a pipe is a common technique to keep running water warm in the winter. Integral knowledge of water temperature within a buried pipe can provide theoretical basis for decreasing burial depth and keeping water warmer. Also, it has practical significance for popularizing of central water supply engineering. On the basis of quasi-three dimensional numerical method, the effect of soil moister, ground surface temperature, buried depth, pipe diameter, water flow velocity and inlet water temperature when the pipe temperature at lowest are discussed in this thesis. No matter how the above factors change, the water temperature will go down with the conveying distance. The cooling rate of pipe decreases quickly firstly, then slowly with increasing of soil moister and burial depth and rising of ground temperature. When the pipe is buried below the frost line, effect of season- ally frozen soil layer on pipe can be ignored. With decreasing of pipe diameter and water flow velocity, the cool- ing rate will increase. Water flow velocity has a reciprocal relationship with the cooling rate. Additionally, the pipe cooling rate increases exponentially with the rising of inlet temperature.