太陽能多效擴散式蒸餾器之研究

Research on Multiple-effect diffusion solar still

張仕林(Tze-Ling Chong)

指導教授 ： 高涌泉

共同指導教授 ： 黃秉鈞(Bin-Juine Huang)

國立臺灣大學/理學院/物理研究所/博士(2014年)

https://doi.org/10.6342/NTU.2014.01311

摘要

蒸餾器主要應用於海水淡化和淨水設備，為將含有雜質的水加熱蒸發，再將水蒸氣凝結而得到乾淨的純水。多效擴散式蒸餾器(MDU)是一種特殊結構的蒸餾裝置，緊鄰的蒸發面和凝結面間距很小，故質傳熱阻(擴散質傳)很低，再加上多次重複使用入熱 (多效)，故有很高的效率。本論文主題為MDU和太陽能MDU (MEDS)之研究。
研究的第一部份內容是MDU的設計和製造工藝。本研究共開發兩種形式的MDU，第一種為傳統MDU改良的彎曲式分隔片設計(MDU-b)，第二種為本研究創新的螺旋式分隔片設計(MDU-s)。MDU-s的設計除擁有熱損小、結構可靠等優點外，其還突破傳統MDU的製作瓶頸，大幅降低生產成本和難度，故擁有很高的商品化潛力。
研究的第二部份內容是MEDS系統整合和測試分析。利用高效的真空管太陽能集熱器和熱導管，結合MDU-b和MDU-s完成太陽能蒸餾系統MEDS-b和MEDS-s。系統經過長期的實際測試和分析，並將結果與文獻比較。MEDS-b和MEDS-s的最高實測單位集熱面積日產水量約分別為25kg和39kg (在單位面積日累積輻射量為25MJ時)，都已遠超過文獻的最高實測記錄(約20 kg)。
研究的第三部份內容是MDU的設計和經濟效益分析。本研究建立傳統平板式MDU (MDU-f)和MDU-s的理論模型和經驗公式，利用不同的設計參數變化，以數值方法求解，評估其經濟效益，以分析較佳的MDU設計方式。從分析結果知道，縮小間隙、提高加熱溫度、增加散熱能力、降低出水熱損量，都是提高MDU效益的方式。MDU可根據不同的成本結構，計算出最符合經濟效益的最佳效數設計。若MDU-s使用太陽能為入熱時，採取較佳的設計，其效益將高於傳統MDU。成本分析顯示，MDU-s和MEDS-s在應用於海水淡化時的產水成本，足以與其他主流海水淡化技術價格競爭。

關鍵字

太陽能 ； 多效蒸餾 ； 太陽能蒸餾 ； 擴散式蒸餾 ； 海水淡化 ； 產水成本 ； 螺旋式

並列摘要

A distiller (still) is mainly used for desalination and water purification, by heating water with impurities evaporating to vapor, and condensing the vapor to get clean water (distillation). A multiple-effect diffusion still (MDU) is a still with particular structure, the evaporated surface is close to condensed surface in each still cell, then the resistance of thermal mass transfer (diffusion) is low, furthermore, the incoming heat is reused repeatedly (multiple-effect) to increase the efficiency. Research on multiple-effect diffusion solar still (MEDS) and MDU are the topics of this thesis.
The first content of the research is the design and manufacturing technique of MDU. Two types of MDU were developed, the first ameliorated traditional MDU by bending partition plate design (MDU-b), the second was an innovation design with spiral shape partition plate (MDU-s). The design of MDU-s has high potential to be commercialized with advantages of less heat loss, reliable structure, surmount manufacturing problems of MDU, and significantly reduce the production cost and difficulty.
The second content of the research is system integration, test and analysis of MEDS. The systems of MEDS-b and MEDS-s were completed by using heat pipe to combine MDU-b and MDU-s with high efficiency vacuum tube solar collector respectively. Long term test and analysis of the systems were carried out, and the results were compared with the literatures. The highest measured dairy pure water production per unit area of collector of MEDS-b and MEDS-s are 25 kg and 39 kg respectively, with 25 MJ of daily-total solar irradiation per unit area of collector, higher than the record in literatures (about 20 kg).
The third content of the research is the design and economic analysis of MDU. Theoretical model and empirical formula of flat-plate MDU (MDU-f) and MDU-s were established. Numerical methods were used to solve the heat balance equations. The performance and economic assessment with difference design parameter were analyzed to decide the optimal design. It’s show that narrowing the gap, increasing heating temperature, increasing heat dissipation capacity and decreasing heat loss of outlet water, can improve the economic of MDU. For a given cost composition of MDU, there is optimal number of effect which minimize the production cost of water. If solar energy is utilized, some optimal design will make MDU-s more benefit than traditional MDU. Cost analysis show that, if MDU-s and MEDS-s are utilized for sea water desalination, the freshwater production costs are comparable with other mainstream desalination technology.

並列關鍵字

Solar still ； Distillation ； Solar energy ； Multiple effect ； Diffusion ； Desalination ； Spiral still

參考文獻

[1] M. Telkes, Solar still construction, US Department of the Interior, Office of Saline Water Research and Development, Progress Report No. 33 (1959).

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[6] P.J. Le Goff, M.R. Jeday, Development of a Rugged Design of a High Efficiency Multi-Stage Solar Still, Desalination 82 (1991) 153-163.

[7] S. Toyama, T. Aragaki, K. Murase, K. Tsumura, Simulation of a multiple-effect solar distillatory, Desalination 45 (1983) 101-108.

[8] S. Toyama, T. Aragaki, H.M. Salah, K. Murase, Dynamic characteristics of a multistage thermal diffusion type solar Distillator, Desalination 67 (1987) 21-32.