石化能源使用量越來越高，然現今石化能源逐漸短缺，而工業的能源使用率卻不到50%，將近一半的能源以廢熱或者其餘無法加以利用之型態的型態排放至空氣中，自然環境逐漸惡化，對於廢熱回收或者自然熱源(如地熱)的再利用人們也越來越重視，而本實驗室也針對工廠廢熱回收系統研究多年，從次臨界循環系統發展(有機朗肯循環，ORC)逐漸發展至本研究所著重之超臨界循環系統(超臨界二氧化碳布雷頓循環)。
選用二氧化碳的原因是基於其流體穩定性佳、臨界點條件低、取得來源難度低以及適用範圍廣，並且可減少環境中的溫室氣體。而其中TAC設備為超臨界循環系統中的一大重點，當中所使用的壓縮機與膨脹機轉子之設計更是為一大困難點，針對其工作條件的限制選擇使用徑向式轉子做為壓縮機與膨脹機的元件，為了減少設計難度以P-15噴射引擎之轉子做為基礎模型，但其葉片形狀仍需依照其設計點進行修改，而後再進行CFD模擬並反覆修正重大錯誤以增進轉子效率。而為了減少初步實驗的難度與危險性也將封閉循環改為半封閉循環以進行實驗設計。

As the fossil fuel consumption is increasing, the energy shortage has gradually become a big problem nowadays. However, the industrial energy utilization is less than 50%, which means almost half of the precious energy is discharged into the air as waste heat or other forms that cannot be further used. The environment is deteriorating, so people are more concerned about the waste heat recovery and the uses of renewable energies (such as geothermal energy). Our laboratory has focused on researches about waste heat recovery system for plants for many years. From subcritical cycle systems (Organic Rankine Cycle, ORC) to supercritical cycle systems (Supercritical CO2 Brayton Cycle), the latter is our main research at present.
The reasons for choosing CO2 as working fluid are because of its stability, low critical point conditions, wide range of applications and greenhouse gas reduction. The Turbine-Alternator-Compressor (TAC) component is a very important part in supercritical Brayton cycle system, especially the designs of rotors in compressor and expander, which are extremely difficult. The radial type of rotor is used both in compressor and turbine, and to reduce difficulties, I used the rotor of P-15 jet engine as basic model, but its blade shape still need to be modified corresponding to design points. Then CFD simulation is applied to improve rotor efficiency by repeatedly correct errors. At last, semi-closed system is used to reduce the difficulties of initial test and also for the safety issues.

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