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| 題名: | 反向電透析(RED)產電效能評估 -以濃度、流速、膜對數及流道厚度為操作參數;Evaluation of concentration, space velocity, cell pairs and channel thickness for power generation by Reverse Electrodialysis(RED) |
| 作者: | 蔡承桓;Tsai, Cheng-Huan |
| 貢獻者: | 環境工程研究所 |
| 關鍵詞: | 反向電透析;濃度梯度;可再生能源;碳排放;reverse electrodialysis;salinity gradient power;renewable energy;carbon emission |
| 日期: | 2023-01-18 |
| 上傳時間: | 2023-05-09 18:17:04 (UTC+8) |
| 出版者: | 國立中央大學 |
| 摘要: | 本研究是目前台灣少數投入於反向電透析(Reverse electrodialysis，RED)之研究，為國內發展新型可再生能源有著重要貢獻，能源議題是國際間重要議題，發展可再生能源替代傳統化石能源以降低二氧化碳(CO2)排放相當重要。藍色能源(blue energy)是存在於海洋之可再生能源，包含波浪、潮汐、鹽差能等，鹽差能是其中能源獲取效率最高者，而RED是用於收集鹽差能最有效的方法，RED原理是利用交錯排列陰陽離子交換膜形成隔室並通入濃、淡鹽水，鹽水因濃度梯度(salinity gradient)形成離子流，經過陰陽極反應後形成電流再經由外部電路收集。根據研究，傳統化石能源碳排放為1,004 g CO2/kWh(燃煤)、543 g CO2/kWh(天然氣)，RED收集之鹽差能碳排放為<10 g CO2/kWh，相較之下RED於碳排放減量上具有良好的競爭力。影響RED發電之因素眾多，包含溶液條件(濃度、種類、流速等)、離子交換膜條件、電極系統條件等，本研究主要利用5對10 x 20 cm2之RED系統進行實驗，針對不同RED操作條件，如濃、淡水濃度、流速與離子交換膜對數及流道厚度四項參數進行比較。在維持所有條件下僅提升濃水濃度或降低淡水濃度，對於RED系統之電壓及功率有幫助，但過高之濃水取得有限、過低之淡水導電率下降反而可能導致最終功率下降，經過評估顯示較佳之濃水、淡水濃度應介於1 ~ 2.5 M NaCl、0.02 ~ 0.05 M NaCl，濃度比則應高於50：1;溶液流速快慢會影響離子交換效率及RED系統電阻，其中淡水流速快慢影響較濃水高，在RED系統整體流速增加時，RED發電之功率呈現先下降後上升，在泵能耗納入考量後，以濃、淡水空間流速0.25、0.25 1/min(流量47.5、47.5 mL/min)可以得到較佳之功率密度(0.328 W/m2);離子交換膜對數則影響RED系統之電壓，在未來實際投入實廠之RED系統必須盡可能增加膜對數以獲取更高效率之能源產生;流道厚度則主要影響RED系統之電阻，當厚度達到4 mm，電阻上升至約11 Ω，將大幅降低RED系統之發電效率，然而厚度過小亦可能造成流道製作過程困難，在厚度之設計上應介於1 mm左右。本實驗主要提供了目前國內首個實驗室級RED系統之操作參數建立，以提供後續研究之參考依據。;This research is currently one of a few research in Taiwan that has focused on reverse electrodialysis (RED), which has made an important contribution to the development of renewable energy in Taiwan. Energy issues are important international issues, and the development of renewable energy to replace traditional fossil fuel to reduce carbon dioxide (CO2) emissions are extremely important. Blue energy is a renewable energy that only exists in the ocean, including waves, tides, and salinity gradient power (SGD). Salinity gradient energy is the most efficient energy source among them, and RED is the most effective way to collect energy. The fundamental mechanism of RED is to use staggered anion and cation exchange membranes to form compartments that concentrated and dilute salt water can flow through respectively. The salty water forms an ion flow due to the concentration gradient, a current is formed after the redox reactions, and then collected by an external circuit. According to the previous research, the carbon emission of traditional fossil fuel is 1004 g CO2/kWh for coal and 543 g CO2/kWh for natural gas. On the other hand, the carbon emission of salt gradient energy collected by RED is <10 g CO2/kWh. It has good competitiveness in terms of emission reduction. There are several factors affecting RED power generation, including solution conditions (concentration, type, flow rate, etc.), ion exchange membrane conditions, electrode system conditions, etc. This study mainly uses 5 pairs of 10 x 20 cm2 RED systems to conduct experiments. Various concentrations, space velocity, cell pairs and channel thickness are applied to compare the efficiency of power generation. Evaluation shows that the concentration of concentrated water and dilute water should be between 1 ~ 2.5 M NaCl and 0.02 ~ 0.05 M NaCl, and the concentration ratio should be higher than 50 : 1. The velocity of the solution affects the ion exchange efficiency and the resistance of the RED system. The velocity of the dilute water is higher than that of the concentrated water. When the overall flow rate of the RED system increases, the power of the RED power generation decreases first and then increases. After the pump energy consumption is taken into consideration. The better power density (0.328 W/m2) can be obtained with space velocity of 0.25-0.25 1/min (flow rate of 47.5, 47.5 mL/min). The cell pairs of RED system must be increased as much as possible to obtain more efficient energy generation. The thickness of the channel mainly affects the resistance of the RED system. The thickness design should be around 1 mm. This experiment mainly provides the establishment of the operating parameters of the first laboratory-level RED system in Taiwan, so as to provide a reference for follow-up research. |
| 顯示於類別: | [環境工程研究所 ] 博碩士論文
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