Study On The Influence Of Fireproof Sealing On Tunnel Cable Based On Multi-Physical Field Simulation

Tunnel cluster laying of cable has been more and more widely used in urban power transmission cable lines due to its advantages of laying multiple circuits and high cross-section load capacity.In order to avoid the aggravation of fire in the cable tunnel,a power supply company requires a full fireproof sealing in the tunnel.However,fireproof sealing will affect the air circulation in the cable tunnel,thereby affecting the heat dissipation of the cable and its operating state.In order to improve the reliability of cable operation,it is necessary to carry out research on the impact of fireproof sealing on the operation of cable laying in tunnel clusters.Firstly,the finite element simulation models of 2D electromagnetic-thermal-circuit coupling field and 3D thermal-fluid coupling field of tunnel cable line are established,and their correctness are verified by the circulating current experiment and temperature measurement experiment of the actual cable line.Then,under the same operating conditions and environmental parameters,the influence of fireproof sealing on the thermal field and fluid field in cable tunnel when the fireproof door is normally opened and the influence of fireproof door mistakenly closed on the tunnel cable are compared.Finally,the influence of the size of the fire door on the thermal field and fluid field of the fireproof sealing tunnel is studied.The results show that the fluid field distribution behind the fire door is changed by the fireproof sealing structure,which leads to the change of the thermal field distribution.When the fire door is opened normally,the air flow velocity around the fire door increases obviously.The heat accumulated by the cables on both sides of the fire door at the fireproof sealing place can be transferred along the axis and around.The change of the fluid field distribution is conducive to the heat dissipation of the cables as a whole.When the fire door is closed by mistake,the axial ventilation of the tunnel is limited,which makes the temperature of the cable rise significantly,which is not conducive to the operation of the cable.Within the adjustable range of the fire door size,the maximum temperature of the cable is basically positively related to its width and negatively related to its height.