Effect of rainfall transients on thermal and moisture exposure of underground electric cables
Effect of rainfall transients on thermal and moisture exposure of underground electric cables
复制标题
降雨瞬变对地下电缆热暴露和湿气暴露的影响
DOI：
10.1016/j.ijheatmasstransfer.2014.09.070
复制
发表时间：
2015
影响因子：
5.2
通讯作者：
Fuhrmann, Andrew P.
中科院分区：
文献类型：
--
作者：
Marshall, Jeffrey S.;Fuhrmann, Andrew P.
电缆载流量分析通常在假设恒定的最坏状态环境条件下进行，这通常对应于干燥土壤条件或具有均匀的周围土壤含水量的条件。土壤热变化的特征时间尺度很大，大约为几周，并且与许多地理位置的降雨事件之间的时间尺度相似。间歇性降雨事件会带来显着的瞬态波动，通过增加土壤的导热性和增加电缆绝缘层的湿气暴露，影响埋地电缆周围的热条件和水分含量。本文报告了降雨事件对埋地电缆周围热和湿度瞬变影响的计算研究。计算是通过有限差分法使用重叠网格方法进行的，内部极坐标网格围绕电缆，外部笛卡尔网格。将在周期性降雨事件的计算中观察到的热和湿度瞬变与稳定均匀降雨的控制计算进行比较。在周期性降雨条件下，观察到温度和湿度场接近极限循环条件，其中电缆表面温度和湿度随时间振荡，但平均值与稳态值显着不同。
Cable ampacity analysis is generally performed assuming constant worst-state environmental conditions, which often correspond to a dry soil condition or to a condition with uniform ambient soil moisture content. The characteristic time scale of thermal variation in the soil is large, on the order of several weeks, and is similar to the time scale between rainfall events in many geographic locations. Intermittent rainfall events introduce significant transient fluctuations that influence the thermal conditions and moisture content around a buried cable both by increasing thermal conductivity of the soil and by increasing the moisture exposure of the cable insulation. This paper reports on a computational study of the effect of rainfall events on the thermal and moisture transients surrounding a buried cable. The computations were performed with a finite-difference method using an overset grid approach, with an inner polar grid surrounding the cable and an outer Cartesian grid. The thermal and moisture transients observed in computations with periodic rainfall events were compared to control computations with a steady uniform rainfall. Under periodic rainfall conditions, the temperature and moisture fields are observed to approach a limit-cycle condition in which the cable surface temperature and moisture content oscillate in time, but with mean values that are significantly different than the steady-state values.
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DOI：
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期刊：
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