太陽能驅動薄膜蒸餾海水淡化系統之設計與可操作度分析

Design and Operability Analysis of Solar Driven Membrane Distillation in Desalination Systems

張舜傑(Shun-Chieh Chang)

指導教授 ： 何啟東

淡江大學/工學院/化學工程與材料工程學系碩士班/碩士(2012年)

https://doi.org/10.6846/TKU.2012.01349

摘要

本論文提出一種系統方法來研究太陽能驅動薄膜蒸餾海水淡化系統的設計與可操作性之間的相互作用。其探討直接接觸式薄膜蒸餾（DCMD）與氣隔式薄膜蒸餾（AGMD）進行模組分析。藉由Aspen Custom Molder（ACM）平台，建立各單元模式與運算出年總成本(TAC)函數。利用自由度(DOF)分析，尋找出最適化變數並在不同日照量情況下，產能維持固定，得到最小年總成本。在穩態分析結果，DCMD系統比AGMD系統需要極大太陽能集熱器，導致AGMD系統的TAC較便宜。運用兩個儲熱槽做替換來克服白天與夜晚的控制操作，DCMD和AGMD的最適化設計發現操作範圍皆很小，其皆受到集熱器溫度限制。為了擴大兩系統可操作範圍，將集熱器出口溫度限制條件從95℃改變至75℃，其可增加操作範圍但相對提高成本。最後進行動態模式驗證，不管晴天或是多雲系統皆能穩定的輸出淡水產量。

關鍵字

直接接觸式薄膜(DCMD) ； 氣隔式薄膜(AGMD) ； 海水淡化 ； ACM軟體 ； 最適化設計 ； 年總成本 ； 可操作性

並列摘要

In this work, we propose a systematic method to study the interaction between design and operability of solar heated membrane distillation seawater desalination systems. Direct contact membrane distillation (DCMD) and air gap membrane distillation (AGMD) modules were explored. Aspen Custom Molder (ACM) platform was used to model and simulate each unit of the system and establish the cost function for counting total annual cost (TAC). From Design degree of freedom (DOF) analysis, design parameters were investigated and used as optimization variables to find the minimum TAC with fixed distillate water production rate by varying the solar energy density. The steady-state simulation result shows the solar driven AGMD desalination systems give the cheaper TAC compared to DCMD ones because of the need for larger size solar collectors for DCMD systems. A secondary hot water storage tank was used and a control structure was proposed to overcome day and night operation. The optimal design for DCMD and AGMD gave a very small operating range due to temperature constrain in effluent stream of solar collectors. In order to widen the operability range of two different plants, the effluent temperature constrains changed from 95 ℃ to 75 ℃. It enlarged the operability range but gave a higher TAC. Finally, the dynamic control results show and verify that the pure water production can be maintained at a very stable level in sunny or cloudy weather by two systems.

並列關鍵字

Direct contact membrane distillation ； Air gap membrane distillation ； Desalination ； ACM software ； Optimal design ； TAC ； Operability

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