液流电池系统储液罐中电解液的混合损失及导流策略

doi:10.19799/j.cnki.2095-4239.2022.0693

储能科学与技术 ›› 2023, Vol. 12 ›› Issue (4): 1148-1157.doi: 10.19799/j.cnki.2095-4239.2022.0693

液流电池系统储液罐中电解液的混合损失及导流策略

王志文, 叶强()

上海交通大学机械与动力工程学院，上海 200240

收稿日期:2022-11-24 修回日期:2022-12-17 出版日期:2023-04-05 发布日期:2023-05-08
通讯作者: 叶强 E-mail:qye@sjtu.edu.cn
作者简介:王志文（1998—），男，硕士研究生，研究方向为液流电池模拟研究；
基金资助:
国家自然科学基金(51776120)

Investigation of the mixing loss and guiding strategy of the electrolyte flow in the tanks of a redox flow battery system

Zhiwen WANG, Qiang YE()

School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Received:2022-11-24 Revised:2022-12-17 Online:2023-04-05 Published:2023-05-08
Contact: Qiang YE E-mail:qye@sjtu.edu.cn

摘要/Abstract

摘要：

在液流电池电堆运行的过程中，储液罐中的电解液的荷电状态并不均匀，其均值与电堆出口流回储液罐的电解液的荷电状态也有差异。处于不同荷电状态的电解液在储液罐内的浓差扩散会造成能量损失。为了定量研究储液罐中不同荷电状态的电解液混合对系统效率的影响，本工作在电解液完全均匀混合与不混合两种极限情况下对电堆的充放电过程进行了模拟研究，进而分析了真实储液罐中的传质过程并将其与完全均匀混合假设下的结果进行比较。最后根据储液罐中传质过程导致的能量损失来源，提出了利用导流结构来优化罐内电解液传质的策略。研究表明：储液罐中不同荷电状态的电解液混合会使得系统的电解液利用率降低、电压效率下降且对电压效率的影响能够达到1%以上；真实储液罐中与传质相关的损失还受到流动死区的影响，死区的存在不但减小了储液罐中实际可以利用的体积还使得局部区域的浓度梯度增大进一步增加了混合损失。合理设计的导流结构能够减小浓度梯度与扩散面积，本工作对某典型储液罐结构做了初步设计，旨在从减小混合损失的角度出发为液流电池储液罐的设计提供思路。

关键词: 混合损失, 储液罐, 导流策略, 系统效率

Abstract:

In a running redox flow battery system, the state of charge (SOC) of the electrolyte in the tanks is not uniform and is different from that of the electrolyte in the outlet of the stack. The mixing of electrolyte with different SOC results in energy loss in tanks. Thus, this paper reports a model-based study on the performance of a redox flow battery under the conditions of complete mixing and nonmixing of electrolytes in the tanks in order to quantify the effect of electrolyte mixing in the tanks on the efficiency of the system. The transport of active species in a real tank is also analyzed and compared with that under complete mixing condition. A diversion structure is proposed to optimize the electrolyte flow in the tanks to minimize the mixing loss in the tank. The results show that the mixing of electrolytes with different SOC in the tanks reduces the utilization rate of electrolyte and the voltage efficiency of the redox flow battery system, and the influence on the voltage efficiency may reach more than 1%. The mass transfer correlated energy loss in the real tank is also affected by the dead zone, where the electrolyte is stagnant. The dead zone reduces the available volume in the tank and increases the concentration gradient adjacent to the dead zone; this leads to increased mixing loss. The use of partition contributes to the reduction of concentration gradient and cross-sectional area of diffusion. This paper also creates a preliminary design for a novel tank structure, aiming to provide ideas for the design of tanks from the perspective of reducing mixing loss.

Key words: mixing loss, electrolyte tank, electrolyte guiding strategy, system efficiency

中图分类号:

TM 911

王志文, 叶强. 液流电池系统储液罐中电解液的混合损失及导流策略[J]. 储能科学与技术, 2023, 12(4): 1148-1157.

Zhiwen WANG, Qiang YE. Investigation of the mixing loss and guiding strategy of the electrolyte flow in the tanks of a redox flow battery system[J]. Energy Storage Science and Technology, 2023, 12(4): 1148-1157.

图/表 11

图1

表1

模型几何参数表"

参数	描述	数值
$H e l e$	电极高度/ $c m$	40
$W e l e$	电极宽度/ $c m$	50
$L e l e$	电极厚度/ $m m$	5
$L m e m$	膜厚度/ $m m$	0.207
$H t a n k ①$	储液罐高度/ $m$	6
$R t a n k ①$	储液罐半径/ $m$	1.5
$H t a n k ②$	储液罐高度/ $m$	3.375
$R t a n k ②$	储液罐半径/ $m$	2
$D p i p e$	储液罐出口直径/ $c m$	15
$L b a f f$	导流板厚度/ $c m$	2
$H b a f f$	导流板高度/ $m$	5.8

表1

表2

电极和电解液物性及动力学参数表"

参数	描述	数值
$σ s e$	电极电导率/( $S / m$ )	$200$
$σ l m$	膜电导率/( $S / m$ )	$5$
$ε$	电极孔隙率	$0.93$
$a$	电极比表面积/ $m$ ^-1	3.5×10⁴
$D V 2 +$	二价钒离子扩散系数/( $m 2 / s$ )	4×10^-11
$D V 3 +$	三价钒离子扩散系数/( $m 2 / s$ )	4×10^-11
$D V O 2 +$	四价钒离子扩散系数/( $m 2 / s$ )	6.5×10^-11
$D V O 2 +$	五价钒离子扩散系数/( $m 2 / s$ )	6.5×10^-11
$D H +$	氢离子扩散系数/( $m 2 / s$ )	1.55×10^-9
$D H S O 4 -$	硫酸氢根离子扩散系数/( $m 2 / s$ )	2.2×10^-10
$D S O 4 2 -$	硫酸根离子扩散系数/( $m 2 / s$ )	1.8×10^-10
$k +$	正极反应速率常数/( $m / s$ )	2.5×10^-8
$k -$	负极反应速率常数/( $m / s$ )	7×10^-8

表2

表3

求解域中各离子初始浓度"

参数	描述	数值
$c V 2 + 0, t a n k$	储罐中二价钒离子初始浓度/( $m o l / m 3$ )	1200
$c V 3 + 0, t a n k$	储罐中三价钒离子初始浓度/( $m o l / m 3$ )	300
$c H + 0, t a n k$	储罐中氢离子初始浓度/( $m o l / m 3$ )	4237.5
$c H S O 4 - 0, t a n k$	储罐中硫酸氢根离子初始浓度/( $m o l / m 3$ )	2542.5
$c S O 4 2 - 0, t a n k$	储罐中硫酸根离子初始浓度/( $m o l / m 3$ )	2857.5
$c V 2 + 0, c e l l$	负极二价钒离子初始浓度/( $m o l / m 3$ )	225
$c V 3 + 0, c e l l$	负极三价钒离子初始浓度/( $m o l / m 3$ )	1275
$c V O 2 + 0, c e l l$	正极四价钒离子初始浓度/( $m o l / m 3$ )	1275
$c V O 2 + 0, c e l l$	正极五价钒离子初始浓度/( $m o l / m 3$ )	225
$c -, H + 0, c e l l$	负极氢离子初始浓度/( $m o l / m 3$ )	3628.1
$c +, H + 0, c e l l$	正极氢离子初始浓度/( $m o l / m 3$ )	4565.6
$c -, H S O 4 - 0, c e l l$	负极硫酸氢根离子初始浓度/( $m o l / m 3$ )	2176.9
$c +, H S O 4 - 0, c e l l$	正极硫酸氢根离子初始浓度/( $m o l / m 3$ )	2739.4
$c -, S O 4 2 - 0, c e l l$	负极硫酸根离子初始浓度/( $m o l / m 3$ )	2863.1
$c +, S O 4 2 - 0, c e l l$	正极硫酸根离子初始浓度/( $m o l / m 3$ )	2300.6

表3

图2

图3

图4

图5

图6

图7

图8

参考文献 8

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液流电池系统储液罐中电解液的混合损失及导流策略

Investigation of the mixing loss and guiding strategy of the electrolyte flow in the tanks of a redox flow battery system

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