Reverse electrodialysis: Performance of a stack with 50 cells on the mixing of sea and river water
Reverse electrodialysis: Performance of a stack with 50 cells on the mixing of sea and river water
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DOI：
10.1016/j.memsci.2008.11.015
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发表时间：
2009-02-05
影响因子：
9.5
通讯作者：
Harmsen, G. J.
中科院分区：
文献类型：
--
作者：
Veerman, J.;Saakes, M.;Harmsen, G. J.
反向电渗析（RED）的目的是在两种溶液混合时产生电力。我们研究了功率密度（W/m（2））和能量效率（与热力学最大值相关的指定体积的河水和海水产生的能量）。在50个电池（10 cm x 10 cm）的堆中，用人工河水（1 g NaCl/L）和人工海水（30 g NaCl/L）获得了0.93 W/m2的功率密度，这是RED报告的最高实用值。这一数值的实现得益于采用系统测量协议的优化电池设计。功率密度的主要因素是电池电阻。使用所用的膜（Fumasep FAD和FKD）和200 μ m的间隔物厚度，在RED条件下测得0.345 Ω的电池电阻。这大约是单个组成部分的预期贡献值的1.5倍。这个高值可能是由间隔物的屏蔽效应引起的。在400 mL/min的流量下，水力损失导致的最大净功率密度约为0.8 W/m2，在此最佳条件下，抽水所消耗的功率约占总发电量的25%。在最大功率条件下（电流密度约为-30A/m2，流速为300 mL/min）进行了多级实验。在这些条件下，理论能量效率最大为50%。然而，在实践中，单个电池堆的能量效率为9%。如此操作的烟囱的流出物浓度用于第二实验等，模拟多级操作。通过3个阶段，实现了18%的累积能源效率。第四阶段没有增加这个值。3级的功率密度加起来是第一级功率密度的50%，表明能量效率和功率密度是相互抵消的。通过更好的垫片和歧管设计，可以进一步提高功率密度和能量效率。更开放的间隔器在两个方面对RED有利：更少的屏蔽和更低的压降。较少的屏蔽降低了电池的电阻。较低的压降允许使用较薄的水隔室，再次导致电池的电阻降低和功率密度的提高。(c)2008 Elsevier B. V.保留所有权利。
The purpose of reverse electrodialysis (RED) is to produce electricity upon the mixing of two solutions. We studied the power density (W/m(2)) and the energy efficiency (the amount of energy produced from specified volumes of river and sea water in relation to the thermodynamic maximum). With a stack of 50 cells(of 10 cm x 10 cm), a power density of 0.93 W/m(2) was obtained with artificial river water(1 g NaCl/L) and artificial sea water (30 g NaCl/L), which is the highest practical value reported for RED. This value is achieved due to an optimized cell design using a systematic measurement protocol.The main factor in the power density is the cell resistance. With the used membranes (Fumasep FAD and FKD)and a spacer thickness of 200 mu m, a cell resistance of 0.345 Omega is measured under RED conditions. This is about one and a half times the value as expected from the contribution of the individual components. This high value is probably caused by the shielding effect of the spacers. The largest contribution to this resistance (about 45%) is from the river water compartment.The hydrodynamic loss resulted in a maximal net power density of about 0.8 W/m(2) at a flow rate of 400 mL/min. At this optimum the consumed power for pumping is 25% of the total generated energy. The majority of the pump power is lost in the manifolds.Multistage experiments were performed at maximal power conditions (a current density of about -30A/m(2) and at a flow rate of 300 mL/min). At these conditions the theoretical energy efficiency is maximal 50%. In practice however, the energy efficiency of a single stack is 9%. The effluent concentrations of the so operated stack are used for a second experiment and so on, simulating a multistage operation. With 3 stages a cumulative energy efficiency of 18% is achieved. A fourth stage did not increase this value. The power density of the 3 stages together was 50% of the power density of the first stage, indicating that energy efficiency and power density are counteracting.Further increase of power density and energy efficiency can be obtained with a better spacer and manifold design. A more open spacer is beneficial for RED in two ways: less shielding and lower pressure drop. Less shielding decreases the electrical resistance of the cell. A lower pressure drop permits the use of thinner water compartments, resulting again in a decreased electrical resistance of the cell and an improvement of the power density. (c) 2008 Elsevier B.V. All rights reserved.