摘要
沟槽敷设方式下电缆附近的温度场同时受到周围空气、周围土壤和地表空气的影响,对其温度场的分析有助于准确确定沟槽电缆的载流量。该温度场中的热传递过程是流固耦合的,固体区域用热传导微分方程描述,沟槽内空气采用动量方程、能量方程和连续性方程与热辐射方程描述,流体和固体间热传递采用迭代法求解。采用三维有限元和涡量-流函数耦合求解上述热扩散方程,求得整个场域的温度场分布图和沟槽内空气层的流动方程,然后利用迭代法计算沟槽内电缆的载流量,直到导体温度为363K。计算结果显示,沟槽内存在较强的空气自然对流散热,沟槽内单根400mm2 YJV22XLPE电力电缆的载流量为825A,比直埋载流量提高了30%,比排管敷设载流量提高了51.9%。研究结果表明利用有限元和涡量-流函数,可以准确计算沟槽敷设电缆群的流场和温度场分布,从而准确计算沟槽敷设电缆的载流量。
The ampacity of power cables in channel is affected by surrounding air and soil and the air on the ground surface,and analysis of the temperature field is helpful to evaluating the cable＇s ampacity.In the temperature field,the heat transfer is a coupling procedure of solid and fluent,while the heat conduction of solid media can be described by differential equations of heat conduction,and the heat transfer of air gap can be described by energy conservation equations,momentum conservation equations and mass conservation equations.The heat transfer between solid and fluent is solved by an iteration method.All the heat diffuse equations are solved by using finite element method（FEM）and vorticity-stream function,then the temperature distribution of the whole field and the velocity distribution of the air in channel are obtained.Thus,the ampacity of power cables in channel can be calculated using the iteration method in which the calculation ends at the conductor temperature of 363K.According to the simulation,there is strong heat convection in channel,and the ampacity of a single 400mm2 YJV22XLPE power cable is 825A,which is 30%and 51.9% higher than that of buried cable and pipe cable respectively.The research results show that FEM and vorticity-stream function can be used in calculating the temperature distribution and the velocity distribution in channel with high accuracy,from which the accurate ampacity of power cables in channel could be calculated.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2012年第11期3048-3053,共6页
High Voltage Engineering
基金
河北省自然科学基金(E2009000719)~~
关键词
沟槽
电缆群
共轭温度场
涡量-流函数
有限元法
载流量
duct
group of cables
conjugate temperature field
vorticity-stream function
finite element method（FEM）
ampacity
