基于磁热流多场耦合的双沟四回路电缆温度场分布与载流量计算

Temperature Field Distribution and Ampacity Calculation of Double-Channel Four-Circuit Cables Based on Multi-Field Coupling of Electromagnetic-Thermal-Fluid

双沟敷设多回路电缆是一种特殊的集群电缆敷设方案,目前缺乏这种敷设方式下电缆载流量的影响因素研究。文中通过建立基于磁热流多场耦合的有限元仿真模型,分析了双沟敷设多回路电缆的散热特性和载流量影响因素,并提出了相应的改进敷设方案。结果表明:相同负载下,靠近中间沟壁的两回路电缆导体温升更高,是载流量的瓶颈位置;电缆沟宽度的减小使沟内电缆导体温度呈线性升高趋势,且靠近中间沟壁的电缆回路温升幅度更大;回填沙土会加强双沟敷设电缆相互之间的热效应,使电缆载流量大幅降低,此时中间沟壁厚度对沟内电缆载流量影响较大。文中提出的改善敷设方案,对于回填沙土热阻系数较大时的双沟敷设电缆载流量具有显著的提升效果。

The laying of multi-circuit cables with double-channel cable trench is a special installation,and there is a lack of relative researches on the influencing factors of the ampacity of such cables.In this paper,a finite element simulation model based on electromagnetic-thermal-fluid coupling was established to analyze the heat dissipation characteristics and influencing factors of the cables installed in double-channel trench,and a corresponding improved laying scheme was proposed.The results show that,under the same load,the temperature of the two circuits near the middle trench wall is more higher,and this is the bottleneck of the ampacity.The decrease in the width of the cable trench makes the temperature of the cable conductor rise linearly,and the temperature rise of the cable circuits near the middle trench wall is greater.The backfilled sand will strengthen the thermal influence of cables in double-channel,leading to a severe reduction on ampacity.And in that case,the thickness of the middle trench wall will have a great impact on the ampacity of the cables.The improved scheme proposed in this paper can signi-ficantly improve the ampacity of double-chanel cables when the backfilled sand has poor dissipation performance.