碘化氢分解反应过程熵产率最小化  

Minimization of entropy generation rate during hydrogen iodide decomposition reaction process

作　　者：孔锐 陈林根 夏少军[3] 张磊[1,2,3] 李鹏蕾 戈延林[1,2] 冯辉君 KONG Rui;CHEN LinGen;XIA ShaoJun;ZHANG Lei;LI PengLei;GE YanLin;FENG HuiJun(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;College of Power Engineering,Naval University of Engineering,Wuhan 430033,China)

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

出　　处：《中国科学：技术科学》2021年第5期565-579,共15页Scientia Sinica(Technologica)

基　　金：国家自然科学基金项目(批准号:51976235,51606218);湖北省自然科学基金项目(编号:2018CFB708);海军工程大学自主立项科研项目(批准号:20161504)资助。

摘　　要：热化学硫碘循环是一种有潜力的制氢方式,而碘化氢分解反应是制氢过程的关键步骤,碘化氢的分解转化率决定了制氢效率的高低.为进一步从热力学第二定律的角度对碘化氢分解过程进行分析优化,本文建立了碘化氢分解一维活塞流管式反应器模型,并基于有限时间热力学理论,以系统中熵产率最小为优化目标进行研究.考虑传热、流动和化学反应过程的总熵产率,在给定的混合气体进口温度和混合气体进口压力及氢气产率约束条件下进行优化分析,分别考虑管长度固定和自由的两种情况,利用最优控制理论求解管外的热源温度最优分布.结果表明优化后的反应器中管外热源温度和混合气体温度差值存在相对恒定的子区间,并且管外热源的温度变化范围相对热源线性变化的参考反应器更广.与参考反应器相比,管长固定时(L=3 m)最优反应器的总熵产率降低了51.3%,管长自由变化时总熵产率存在二次最优,此时最优反应器长度Lopt=4.91 m,总熵产率相比参考反应器降低了57.6%.总熵产率的降低主要是由降低传热过程不可逆性实现的,适当延长管长可进一步降低反应过程中总熵产率.同时结合工业生产实际对如何实现热源温度最优分布进行了探讨.本文的研究结果对碘化氢分解反应器的尺寸参数和工艺条件设计可提供理论指导.The thermochemical sulfur-iodine cycle is one of the potential hydrogen production processes.The hydrogen iodide(HI)decomposition reaction is the key step in hydrogen production,and the HI conversion rate determines the level of hydrogen production efficiency.To further analyze and optimize the thermodynamic performance of the HI decomposition process from the perspective of the second law of thermodynamics,this paper establishes a one-dimensional plug flow model of the HI decomposition tubular reactor and conducts performance optimization through the minimization of entropy generation rate(EGR)in the decomposition reaction system as an optimization objective based on the finite-time thermodynamic theory.Considering the total EGR of the heat transfer,fluid flow,and chemical reaction processes,the optimization analyses are performed under the given constraints of the mixed gas inlet temperature and pressure and hydrogen production rate.Two cases are considered,first,the tube length is fixed and variable;second,the optimal control theory is used to solve the optimal distribution of the temperature of the heat source outside the tube.The results show that there is a relatively constant sub-interval between the temperature of the heat source outside the tube and temperature of the mixed gas in the optimized reactor.The range of the variation is wider than that of a reference reactor where the heat source varies linearly.Compared with the reference reactor,the total EGR of the optimal reactor with a fixed tube length(L=3 m)is reduced by 35.9%,and there is a twice optimal total EGR when the tube length is freely changed.The optimal reactor length Lopt=4.91 m,and the total EGR is reduced by 40.4%compared with the reference reactor.The reduction of the total EGR is mainly achieved by reducing the irreversibility of the heat transfer process.The total EGR can be further reduced during the reaction process by properly extending the tube length.Simultaneously,how to achieve the optimal distribution of heat source temperatur

关 键 词：有限时间热力学 管式反应器 碘化氢分解反应 熵产率最小化 最优控制理论 

分 类 号：TQ116.2[化学工程—无机化工]