以數值模擬輔助地下電纜洞道內冷卻系統設計

The Design of the Cooling System in the Underground Power Cable Tunnel with the Aid of Numerical Simulation

辛翰宗(Han-Tsung Hsin)

指導教授 ： 施陽正

國立臺北科技大學/機電學院/冷凍空調工程系所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00407

摘要

近年來輸電架空佈設逐漸轉為地下化，若採用以往直埋及管路佈設方式，不僅未來線路擴充困難，且施工時常造成其它管線損壞及道路挖埋等問題，對都市景觀及保養維護管理都會造成影響。地下共同管道之應用是城市發展的趨勢，但超高壓電纜運轉時所散發出的熱量，若無法以合適之方式進行排除，持續高溫造成輸電容量損失增加、電纜絕緣材料劣化及危害維修人員之人身安全等問題。
本論文針對地下電纜洞道若以間接水冷卻系統配設情況下，在不同容量（N-1容量、終期容量100%、50%、30%）、兩種洞道（聯外線路、一般線路）、夏季及冬季等條件下，透過「ANSYS FLUENT」進行模擬分析，結果只有一般線路配設在冬季模式（電纜負載30%）情況下，可滿足洞道內空氣安全溫度之需求；為改善洞道內高溫之情況，故啟動機械式通風系統進行輔助，利用模擬分析及熱阻模型之概念，將分析結果代入熱傳經驗公式進行推導，得知一般線路洞道在夏季模式（電纜負載100%）時，洞道內空氣溫度可維持在安全標準內。此結果可發現與文獻提到的間接水冷卻系統適用低負載情況相符合，若高負載時則須啟動風機與間接水冷卻系統搭配以提高冷卻效率。考量到節能減碳之因素，建議依洞道溫度測量值，分階啟動強制對流進行通風散熱，以達到地下電纜洞道空氣安全溫度之需求。

關鍵字

地下電纜散熱 ； 計算流體力學 ； 機械式通風 ； 自然通風 ； 間接水冷卻 ； 洞道通風冷卻

並列摘要

For the past few years, electric power transmission has gradually converted from overhead to underground power lines. If we were to use the traditional direct-burial cable and pipeline layout as construction methods, future expansion would be significantly impeded. Additionally, the construction would often cause damage to other pipelines and other problems associated with digging which affects the city landscape and its maintenance. Application of underground pipelines is a growing trend in urban development. However, the heat exuded by EHV cables in operation , if its can not be excluded in an appropriate manner, sustained high temperatures resulting in increased transmission capacity loss, deterioration and damage cable insulation material maintenance personnel personal safety and other issues.
In this study, underground-cable tunnels are being examined through the " Ansys Fluent " simulation analysis under the precursor of using indirect water cooling system with the cable capacity in different loads (N-1 capacity, final capacity of 100%, 50% and 30% ), two types of tunnel mapping (Interconnective lines and standard lines), a summer and a winter setting with different parameters to explore.The results show that only when combining standard line mapping in winter(cable load of 30%) does air temperature in tunnels barely satisfies the safety requirements; therefore, through simulation analysis and discuss results through empirical study of heat conduction sourcing from thermal resistance model concept, its empirical calculation and then applying the simulated results in heat conduction empirical extrapolation, it can be derived that when using mechanical ventilation cooling system and indirect water cooling system in the setting of standard line mapping in summer (cable load of 100%), in order to sufficiently meet and maintain the air temperature in tunnels within safety standard.This result has demonstrated that the indirect water cooling system mentioned in the reference is only compatible to low load conditions, and under a high load setting, it is necessary to use forced ventilation system with indirect water cooling system to improve the cooling efficiency.
Considering the Energy Conservation & Carbon Reduction, burrow temperature measurements are suggested to carry out in phases starting forced convection ventilation in order to meet the needs of underground cables in tunnel air safety temperature.

並列關鍵字

Heat dissipation of underground power cables ； Computational Fluid Dynamics (CFD) ； Mechanical ventilation ； Natural ventilation ； Indirect water cooling ； Tunnel ventilation and cooling

參考文獻

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