在現今能源短缺之情況下,如何有效利用再生能源成為目前非常重要的課題之一,目前較被廣泛利用之再生能源為太陽能發電及風力發電,太陽能發電發展至今已被許多民眾利用並裝設於屋頂上,因此本研究欲探討小型風力發電與建築結合之發電情形。但建築物為一有限高度之物體,當氣流在通過一個有限高度之物體時,其部分氣流會沿著建築物之迎風面形成上升氣流,使流體產生會分流現象,使建築物樓頂上產生渦流區,形成之渦流區使樓頂風場呈現紊亂狀態。 由於屋頂上之紊流情況使得風力發電機發電效益下降,本研究利用CFD數值模擬呈現屋頂結合導風板後之流場情形,藉由導風板穩定屋頂上紊亂之流場後,利用風力發電公式計算發電量,以模擬不同葉片長度之小型風力發電機裝設於不同角度導風板後之發電情形。 根據CFD程式模擬結果顯示,建築物結合導風板後確實可穩定屋頂風場,而在本研究之模擬情境中,以20度導風板上裝設風機之年發電效益較佳。經由成本效益分析及敏感度分析後,於導風板角度18度時,搭配葉片半徑2.5公尺之風機且設置數量在12台時,其淨現值(NPV)為NT $2,950,777,期滿所能獲得之終值(FV)為NT$5,056,227,並於躉購期間第10年還本。
In the situation of lacking power resources, how we should make use of renewable energy efficiently has become one of the important issues nowadays. For the time being, solar energy and wind energy are two kinds of renewable energy which are more broadly used. Concerning the solar energy development so far, solar energy has been used by many people and its generation device has been commonly installed on rooftops. This research aims to discuss the electricity generation condition when miniature wind energy generation devices and buildings are combined. Buildings are objects in certain limited heights. When airflow passes through a building, a part of the airflow becomes an upward current along the windward side of the building. The fluid then creates different separated flows, making a vortex zone above the building. The vortex turns the wind filed into turbulent flows. Thus, Stable wind field and wind speed are the main elements for wind turbines to have electricity efficiency. As the turbulent flow on rooftop makes the electricity efficiency of wind turbines decrease, this research presents the airflow on rooftop with CFD simulation after a deflector is installed on the roof. After the deflector steadies the unstable airflow, we calculate the quantity of generated electricity with the wind energy formula in order to imitate different electricity generation conditions in which small wind turbines with fan blades in various lengths are installed on deflectors in different angles. This research shows that deflectors installed on buildings can indeed stabilize the wind field on rooftop according to the result of CFD simulation. In the context of this simulation study, when degrees deflectors to the angle of 18 degrees installed in wind turbines the power generation efficiency of better. By the cost-benefit analysis and the sensitivity analysis, when 12 deflectors are adjusted to the angle of 18 degrees, along with fan blades in the radius of 2.5 meters, the NPV is NT $2,950,777 and the FV by the expired date is NT$5,056,227. The repayment of principal will be resumed ten years after whole purchase.