Energetic performance optimization of a capacitive deionization system operating with transient cycles and brackish water
Energetic performance optimization of a capacitive deionization system operating with transient cycles and brackish water
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DOI：
10.1016/j.desal.2013.01.014
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发表时间：
2013-04-02
期刊：
影响因子：
9.9
通讯作者：
Hidrovo, Carlos
中科院分区：
文献类型：
--
作者：
Demirer, Onur N.;Naylor, Rachel M.;Hidrovo, Carlos
使用电容去离子（CDI）的水脱盐作为用于水脱盐的新技术已经成为最近的密集研究的主题，其能够在用于离子吸附的纳米多孔电极的再生期间返回输入能量的一部分。通常，进行一组连续和交替的脱盐-再生过程以评估在不同操作条件（施加的电势、流速和初始溶液浓度）下这种类型的系统的性能。然而，脱盐和再生过程的时间对电容去离子系统的性能的影响尚未被探索。本文分析了三种不同盐度水平和三种不同CDI系统尺寸的脱盐和再生过程的持续时间对整体系统性能的影响。更具体地，评价能量回收率、热力学效率和每摩尔被处理的每单位体积吸附的盐所需的净能量的变化。为了优化瞬态操作的时机，进行一次脱盐测试直到完全饱和，这通过出口浓度返回到入口浓度来识别。从这个实验中，得到三个特征时间：一个是最小化出口溶液浓度，一个是每能量输入给出最高吸附离子，一个是对应于最大平均吸附速率。在交替脱盐-再生过程中测试这三种定时策略所获得的结果表明存在不同的最佳操作点，这取决于特定的需求，例如最大脱盐速率或最大能量效率。本文提出的方法可以扩展到其他操作条件/系统，以优化其能量性能。(C)2013爱思唯尔有限公司版权所有。
Water desalination using capacitive deionization (CDI) has been a recent topic of intense research as a novel technique for water desalination, capable of returning a fraction of the input energy during the regeneration of nanoporous electrodes used for ion adsorption. Usually, a set of consecutive and alternating desalination-regeneration processes is conducted to evaluate the performance of this type of systems under different operational conditions (applied electric potential, flow rate, and initial solution concentration). However, the effect of timing for desalination and regeneration processes on the performance of a capacitive deionization system has not been explored yet. This paper analyzes the effect of varying the duration of desalination and regeneration processes on overall system performance for three different salinity levels and three different CDI system sizes. More specifically, the variation in energy recovery ratio, thermodynamic efficiency, and net energy required per moles of salt adsorbed per unit of volume treated are evaluated. To optimize the timing for transient operation, one desalination test was performed until total saturation, which is identified by the outlet concentration returning to inlet concentration. From this experiment, three characteristic times were obtained: one that minimizes the outlet solution concentration, one that gives the highest adsorbed ions per energy input and one that corresponds to maximum average adsorption rate. The results obtained from testing these three timing strategies in an alternating desalination-regeneration process suggest the existence of different optimal operational points, depending on the specific needs, such as maximum desalination rate or maximum energy efficiency. The methodology presented in this paper can be extended to other operational conditions/systems to optimize their energetic performance. (C) 2013 Elsevier B.V. All rights reserved.