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標題: | 建構電容去離子裝置與超級電容器之脫鹽-能源回收系統之研析 Integrating Capacitive Deionization with Supercapacitor for Energy Recovery from the Desalination |
作者: | Yu-Wu Chen 陳宥吾 |
指導教授: | 侯嘉洪 |
關鍵字: | 電容去離子技術,電能儲存,電能回收,脫鹽,四開關式電路架構, capacitive deionization,energy storage,energy recovery,desalination,four-switch buck–boost converter, |
出版年 : | 2018 |
學位: | 碩士 |
摘要: | 近年來,由於快速的人口成長、高度的經濟發展,水資源短缺與能源匱乏引起各方的重視,其中,高效率的脫鹽裝置結合能源儲存技術更是受到廣泛的矚目。電容去離子技術(Capacitive deionization, CDI)為低耗能的脫鹽裝置,其工作原理為在兩側多孔碳電極板施加外部電壓,使水溶液中的陰陽離子往帶電荷相反之極板移動,並以電雙層的原理儲存於電極孔洞中,進而達水體脫鹽之目的。此技術具有低能源消耗、高產水率、環境友善性的優勢,且具有電能儲存與回收的潛力更是其最大特色。電容去離子裝置於充電階段,電荷累積儲存於極板上,同時移除水中離子;於放電階段,電能由外部電路釋放,離子被脫附而電極再生。本研究目的為建立電容去離子裝置的電能回收系統,將充電階段所輸入模組的電能於放電階段進行回收,並將回收的電能儲存於超級電容器中。本研究以連續式電容去離子模組進行實驗,模組中碳電極的有效面積為8 8 cm2,充電階段為定電壓模式(施加電壓1.2 V),評估操作條件(進流鹽水濃度為5, 10, 20, 30, 40, 50 mM)與模組結構(碳電極間距為0.9, 2.4, 3.9, 5.4 mm)對脫鹽表現及電能回收效能的影響。
本研究成功建構四開關式電路架構的電能回收系統,以創新的漸進式最大責任週期控制法,將電容去離子模組中的電能有效回收並儲存於超級電容器中。以處理水體為10 mM氯化鈉溶液來說,電容去離子模組之脫鹽量為10.1 mg g−1且能源消耗為0.09 kWh m−3。由研究結果得知,當進流鹽水濃度由5 mM提高至50 mM時,能源回收率由34.8%增加至49.6%,且電能傳輸速率隨進流鹽水濃度的增加而增加;當碳電極間距由0.9 mm增加至5.4 mm時,能源回收率由43.5%減少至15.9%,且電能傳輸速率隨電極間距增加而顯著下降。整體而言,電容去離子模組中的進流鹽水濃度越高、碳電極間距越小,越有利於電能回收與儲存。綜合以上所述,電容去離子模組本身即為低能耗之裝置,本研究更將儲存於模組中高達49.6%的電能進行回收,進一步降低此技術於脫鹽過程中的能源需求,相較於文獻中20%的能源回收率,本四開關式電能回收系統具有相當優異之效能。 Increasing water shortage and energy crisis necessitate energy-efficient desalination and energy storage technologies for sustainable development. With this regard, water–energy nexus in desalination has gained more attention recently. Capacitive deionization (CDI), as a promising electrochemical technique for water desalination, has advantages in low energy requirement, good operating reversibility, and environmental friendliness. Notably, producing freshwater and storing energy simultaneously is the unique feature of CDI. More specifically, the energy stored in CDI during charging step for removal of salt ions could be further recovered during discharging step. In this study, CDI cell was successfully used to remove salt ions at various NaCl concentrations in a range of 5 to 50 mM using a pair of activated carbon electrodes, which had an effective surface area of 8 8 cm2, at an applied potential of 1.2 V. As demonstrated, the deionization capacity (DC) of 10.1 mg g−1 and energy input of 0.09 kWh m−3 were obtained for the desalination of 10 mM NaCl solution. After charging the electrodes, the CDI cell was discharged to release salt ions back to water for regeneration. Meanwhile, the four-switch buck–boost converter that has variable frequency and progressive maximum duty cycle control technique was constructed to directly recover electric energy from the CDI cell to the supercapacitor. All the experiments were operated at single-pass mode. The effect of cell configuration (electrode distance ranging from 0.9 to 5.4 mm) on the desalination performance and energy recovery behavior was further investigated. The energy recovery ratio increased from 34.8 to 49.6% when the influent salt concentration increased from 5 to 50 mM. Also, the energy recovery ratio decreased from 43.5 to 15.9% when the electrode distance increased from 0.9 to 5.4 mm. As a result, a higher energy recovery ratio can be achieved with higher influent NaCl concentration and smaller electrode distance. Note that a superior energy recovery ratio of 49.6% was achieved by our device, which is much higher than that reported in literatures. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/70756 |
DOI: | 10.6342/NTU201802760 |
全文授權: | 有償授權 |
顯示於系所單位: | 環境工程學研究所 |
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