电力管廊通风规律及结构布局优化研究

Ventilation Patterns and Optimization Measures for Electric Power Tunnels

为改善电力管廊的通风效果,依托北京新机场高速公路综合管廊工程,采用数值分析与现场试验的方法,对电力舱通风规律进行系统研究。在得到初步规律的基础上,通过改变通风方式、通风口位置和电缆布局,对比研究机械进风自然排风和自然进风机械排风、通风口设在管廊顶部和两侧、10 k V和110 k V电缆交换位置3类6种工况下的通风效果。结果表明:1)现有正常通风条件下,从进风口到排风口,进风口处气流组织混乱;同时,由于在进风口处气流2次改变运动方向导致能量损失很大,致使可用于驱动管廊内空气的能量减小,通风效果下降,造成能源浪费。2)将通风口(风机)布置在电力舱两侧时,因初始风速与通风方向一致,避免了能量损失,有效提高了通风效果。研究显示,管廊中间断面的平均风速提高了0.31 m/s,变幅达39.6%;温度降低了1.6℃,变幅达6.1%;压力损失降低了13.7 Pa,变幅达30.4%,极大地改善了电力舱通风效果。3)在通风口(风机)位于顶部的条件下,对电缆布局优化后,10 k V电缆表面温度降低3.21℃,110 k V电缆表面温度升高1.68℃,纵断面平均温度下降0.365℃,电缆布局调整有利于降低舱内温度,减少压力损失。

A case study is conducted on a utility tunnel project of the Beijing New Airport Expressway,and the ventilation laws and effects of power cabin are systematically examined using numerical simulations and field experiments.Then,by changing the ventilation mode,the position of the vents,and the layout of the cable,the ventilation effects are studied and compared under three types six working conditions,including the mechanical air intake and natural air emission,the vent set on the top and both sides of the tunnel,and the exchange position of the 10 kV and 110 kV cables.The results show the following:(1)Under the existing normal ventilation conditions,the air flow at the air inlet is chaotic.At the same time,the air flow at the air inlet changes the direction of movement twice,resulting in a large energy loss.As a result,the energy that can be used to drive the air in the utility tunnel is reduced,the ventilation effect is reduced,and energy is wasted.(2)When the vents(fans)are arranged on both sides of the power cabin,the initial wind speed is consistent with the ventilation direction,which avoids energy loss and effectively improves the ventilation effect.According to the research,the average wind speed of the middle section is increased by 0.31 m/s,the amplitude is 39.6%,the temperature is reduced by 1.6℃,up to 6.1%,and the pressure loss is reduced by 13.7 Pa, up to 30.4 % , which greatly improves the ventilation effect of the power cabin. (3) With the ventilation vents(fans) arranged on the top, after optimizing the cable layout, the surface temperature of the 10 kV cable is reduced by 3.21 ℃, the surface temperature of the 110 kV cable is increased by 1.68 ℃, and the average temperature of the longitudinal section is reduced by 0.365 ℃. After the adjustment of the cable layout, it is beneficial to reduce the temperature in the cabin and the pressure loss.