一类普适电化学反应系统的最优电流路径  

Optimal current paths for a class of generalized electrochemical reaction systems

作　　者：夏少军[1] 陈林根 王超[1] XIA ShaoJun;CHEN LinGen;WANG Chao(College of Power Engineering,Naval University of Engineering,Wuhan 430033,China;Institute of Thermal Science and Power Engineering,Wuhan Institute of Technology,Wuhan 430205,China;School of Mechanical&Electrical Engineering,Wuhan Institute of Technology,Wuhan 430205,China)

机构地区：[1]海军工程大学动力工程学院,武汉430033 [2]武汉工程大学热科学与动力工程研究所,武汉430205 [3]武汉工程大学机电工程学院,武汉430205

出　　处：《中国科学：技术科学》2021年第9期1025-1039,共15页Scientia Sinica(Technologica)

基　　金：国家自然科学基金(批准号:51976235)资助项目。

摘　　要：本文研究了一类普适反应类型(aA+bB■xX+yY)下有限时间与非零反应速率的电化学系统,考虑活化过电位、欧姆过电位和浓度过电位等各种内部不可逆性损失,应用有限时间热力学和最优控制理论分别导出了理想搅拌式和耗散流两类燃料电池最大输出功与最大利润时最优电流路径.结果表明:对于理想搅拌式燃料电池,无论是以最大输出功还是以最大利润为优化目标,其最优电流均随时间保持为常数,与过电位损失大小无关;对于耗散流燃料电池,其最大输出功时电压-电流特性曲线呈类抛物线规律变化,最大输出功时电流随时间呈现前半段急剧减小而后半段变化量较小的变化规律,而最大利润时电流随时间呈现前半段急剧减小而后半段急剧增加的变化规律,两种不同目标下电流最优路径间存在显著不同;反应级数的变化对不同目标下的优化结果也有显著影响,简单反应(A+B■X+Y)电化学系统下最大输出功时电流随电压的增加为典型的抛物线关系,而复杂反应(A+2 B■2 X+Y)电化学系统下最大输出功时电流随电压的增加在多数情形下呈近似的单调增加.本文研究结果对实际电化学系统的最优设计与运行具有一定的理论指导意义.This work investigates a class of finite-time nonzero-rate electrochemical systems with the generalized reaction type(aA+bB■xX+yY)and considers various internal irreversibility losses,including activation overpotential,ohmic overpotential,and concentration overpotential.By applying finite time thermodynamics and optimal control theory,the optimal currents for the maximum work output and the maximum profit of both the well-stirred and the diffusive flow fuel cells are derived.Results show that for the well-stirred fuel cell,the optimal current always remains constant versus the time,irrespective of whether the maximum work output or the maximum profit is chosen as the optimization objective,which is independent of various overpotential losses.The optimal voltage-current profile of a diffusive flow fuel cell corresponding to the maximum work output is a parabolic curve.The current versus time profile of the maximum work output decreases sharply in the first half and changes slightly in the second half,whereas that of the maximum profit decreases sharply in the first half and increases sharply in the second half.The optimal current paths for these two optimization objectives are significantly different from each other.The change in the reaction order significantly affects the optimization results for different optimization objectives.In general,the current versus voltage profile of the maximum work output of the electrochemical system with the simple reaction(A+B■ X+Y)is a typical parabolic curve,whereas that of the complex reaction(A+2 B■2 X+Y)is a monotonic increasing curve.The results can provide some theoretical guidelines for the optimum designs and operations of electrochemical systems.

关 键 词：电化学系统 最大输出功 最大利润 最优控制 有限时间热力学 广义热力学优化 

分 类 号：O646[理学—物理化学]