The Study of An Indirect Cooling System for High-Voltage Electrical Cables In Underground Tunnels
Date Issued
2006
Date
2006
Author(s)
Tu, Wen-Hsiang
DOI
zh-TW
Abstract
As far as underground high-voltage electrical cables are concerned, when the cables transmit electric current, a part of electric energy will transform into heat and then dissolve due to electric resistance from the cables themselves. Therefore, designs of cooling systems are the main concern when we try to solve the problem of heat dissipation in underground tunnels where high-voltage electrical cables are installed.
In this research we estimate further possible needs based on preceding literatures regarding several such cooling systems. An experimental apparatus is built to study the performance of an indirect cooling system which cooling water tubes are placed through an insulated tunnel. The modeled tunnel that we engage in the simulated tunnel experiment is set up according to similarity laws. At different sections of the tunnel, tests are conducted to measure temperatures of the tunnel, the cooling water tubes, and the electrical cable. The variables are analyzed and studied and references may then be obtained for an optimal design of an underground high-voltage electrical cable tunnel.
The result shows that the temperature in the tunnel rises in accordance with the increasing distance from the tunnel entrance. At the entrance of the tunnel, the rising degree of the tunnel’s temperature is the most significant. It indicates that the cooling water tubes in the front section of the tunnel take away heat more. The higher the cooling water tubes’ temperature get, the less heat they take away. As for temperature variation of a single section, the temperature drops compliant with the ascending position away from the heater. At the top part of the tunnel, affected by cold air close to the cooling water tubes, the temperature gets lower and lower around the semicircular wall of the tunnel. The temperature gradually drops to the lowest at the lowest point of the semicircular wall of the tunnel. Water-flow exerts a direct impact on the tunnel’s temperature. The slower the water-flow is, the lower the tunnel’s temperature gets. Though the number of cooling water tubes shows insignificant impact on tunnel’s temperature variation, the more the cooling water tubes are, the smoother the temperature distribution is in the front and rear sections of the tunnel. This indicates the heat transform of the cooling system is more even.
Subjects
地下洞道
自然對流
間接水冷
underground tunnel
nature convection
Indirect Cooling System
Type
thesis
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