【作者】 郭斌；

【导师】 丁顺良； 胡松；

【作者基本信息】 郑州大学 ， 机械电子工程， 2024， 硕士

【摘要】 利用可再生能源制得的氢气,即绿氢,具备良好的能量和物质属性,在低碳转型路径中将发挥重要作用。当前,碱性电解水技术在所有电解水制氢技术中具备成本低廉、技术成熟度高、应用市场规模大、发展前景好等优势,成为技术主流与研究热点。然而,窄负载范围和较低电解效率是碱性电解水系统目前仍存在且亟待优化的技术难点。负载下限主要受来自于跨膜传输和碱液混合的氧中氢(Hydrogen To Oxygen,HTO)限制,HTO超2.0%则极易引发安全风险,而降低碱液流速或减小压力是改善HTO并拓宽负载范围的有效手段,但会引起电解效率恶化。基于此矛盾,本文围绕碱性电解水制氢设备负载下限以及电解效率协同优化策略开展机理建模、仿真优化及实验验证研究,主要研究内容如下:首先,建立了制氢设备动态模型,包含电化学、热和气体纯度多物理场,电解槽、气液分离器、换热器等主要设备,以及小时级、分钟级、秒级多时间尺度;通过250 kW动态制氢实验平台的设计开发和稳态/动态实验,获取了工业级别水平的实验数据并进行了模型标定。其次,研究了制氢设备多工况下热-压-电-质物理场响应特性和相互耦合机制,明确了电流、压力、碱液流速等运行参数和温度、氧中氢、氢氧侧气液分离器液位及液位差等关键状态参数的影响规律和耦合作用机理;验证了碱液流速和压力作为实际调控变量在安全方面的可行性,不同碱液流速、压力、电流波动幅度及变化速率及下,液位波动始终能够控制在±10.0 mm范围内。然后,借助?效率分析方法,分析了特征参数(电极电导率、电极间距、膈膜厚度、电解液浓度、气泡覆盖率)和运行条件(压力、温度)对系统效率的影响规律,为改善系统电解效率提供理论参考。在上述基础上,提出了一种基于压力和碱液流速控制的系统负载下限和电解效率协同优化策略,获取了压力和碱液流速最优运行曲线并在高动态风电和光伏发电场景下进行控制效果对比。系统最低负荷下限由单独碱液流速控制模式的42.0%降至单独压力控制模式的21.2%,最终降至碱液流速和压力协同控制模式的15.6%,风、光发电直连制氢的系统平均电解效率分别为70.6%和70.3%,风电利用率高达98.3%,光电利用率高达95.6%。更多还原

【Abstract】 Hydrogen produced from renewable energy source,known as green hydrogen,has excellent energy and material properties and will play an important role in the lowcarbon transition pathway.Currently,alkaline water electrolysis technology has the advantages of inexpensive cost,advanced technology maturity,large application market,and promising development in all water electrolysis hydrogen production technologies.However,narrow load range and relatively poor electrolysis efficiency are the technical difficulties of alkaline water electrolysis system that still exist and urgently need to be optimized.The minimum loading limit is mainly constrained by the hydrogen to oxygen(HTO)from transmembrane transport and lye mixing,and HTO above 2.0%can pose serious safety risks.Reducing the lye flow rate or pressure is an effective means to improve the HTO and widen the loading range,but can cause deterioration in electrolysis efficiency.Based on this contradiction,this thesis focuses on the synergistic optimization strategy of system minimum loading limit and electrolysis efficiency,and carries out mechanism modeling,experimental verification and simulation optimization research:Firstly,a comprehensive dynamic model of the alkaline hydrogen production system is established.This model incorporates multi-physics fields encompassing electrochemistry,heat transfer,and gas purity.Key components such as the electrolyzer,gas-liquid separator,and heat exchanger are incorporated into the model.Furthermore,it accounts for various time scales ranging from hours to minutes and even seconds.Subsequently,through rigorous design and development,troubleshooting,commissioning,and a series of steady-state and dynamic experiments conducted on the 250-kW dynamic hydrogen production experimental platform,representative experimental data at an industrial level is obtained.This data is then utilized to calibrate and refine the dynamic model,ensuring its accuracy and reliability for further analysis and optimization.Secondly,an in-depth study is conducted to investigate the response characteristics and mutual coupling mechanisms among the thermal,pressure,electrical,and mass physical fields under various working conditions of the hydrogen production system.The coupling mechanism and influence rules of operating parameters,including current,pressure,and lye flow rate,as well as key state parameters such as temperature,HTO(hydrogen/oxygen ratio),and gas-liquid separator level difference,are elucidated.This analysis aims to validate the feasibility of utilizing lye flow rate and pressure as practical regulating variables for safety considerations.The results demonstrate that under varying amplitudes and rates of fluctuations in lye flow rate,pressure,and current,the level fluctuation can be consistently maintained within a range of±10.0 mm.Then,the influence of characteristic parameters(electrode conductivity,electrode spacing,diaphragm thickness,electrolyte concentration,bubble coverage)and operating conditions(pressure,temperature)on the system efficiency is carefully analyzed with the help of exergy efficiency analysis method,which provides a theoretical reference for the improvement of the system electrolysis efficiency.On the basis of the above,a synergistic optimization strategy is proposed for minimizing the system’s loading limit while maximizing electrolysis efficiency.This strategy relies on the control of pressure and lye flow rate.The optimal combination curve of pressure and lye flow rate is derived,and its control efficacy on various performance parameters,including minimum load,system energy consumption,energy utilization,and electrolysis efficiency,is evaluated and validated in high-dynamic wind and photovoltaic(PV)power scenarios.The minimum load is extended from 42.0%in the lye flow rate alone control to 21.2%in the pressure alone control and finally to 15.6%in the lye flow rate and pressure synergistic control method.In the absence of electrical replenishment,wind and PV energy utilization efficiency can reach up to 98.3%and 95.6%,respectively.更多还原