Investigation of Heat Dissipation of Power Cable Laid in the Tunnel with Ventilation
To increase the current carrying capacity of the power cable, more and more power tunnel are installed with ventilation. Hence in the paper the heat dissipation of power cable is investigated. Firstly the model to calculate the thermal field of power cable with natural ventilation is presented based on the fluid mechanics and heat transfer, and the governing equations and boundary conditions are inferred. Then the thermal field for six-loop cables in power tunnel was calculated, which verified the accuracy of the model. In addition, the factors influencing the thermal field with ventilation is investigated, including the size of the power tunnel, the distance between the cable. Finally the current carrying capacity of the power cable is calculated and the economic benefit of the operation mode of power cable is analyzed.
Research and Application of Online Temperature and Load Monitoring for Power Cables
Research progress on online temperature and load monitoring for power cables inland and overseas is reviewed, and the theories and techniques used to calculate the core temperature by that on cable surface or insulation surface are analyzed. Application instances overseas presented show the importance to carry out the online temperature monitoring for power cables, especially the high and super-high voltage ones, so as to know the running condition of cables and guarantee operation safety, and to carry out appropriate load scheduling. It also provides successful operating experiences for power departments in China.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.