Modeling Analysis And Design Optimization Of Alkaline Water Electrolysis System For Hydrogen Production

It is an important technological trend to produce green hydrogen by using renewable energy power generation coupled with alkaline water electrolysis.However,due to the characteristics of renewable energy such as volatility and intermittance,alkaline electrolytic system may have the problem of reduced gas purity caused by load fluctuation when coupled with it,which will not only reduce the efficiency of hydrogen production,but also pose a challenge to the security of the system.Therefore,through effective modeling analysis and reasonable design optimization of alkaline hydroelectricity hydrogen production system,not only can the continuity and safety of the system operation be guaranteed,but also can improve its electrolytic efficiency to a certain extent,reduce the equipment and operation costs of the system.In this paper,the voltage model of alkaline electrolytic cell was established by using Simulink software,and the model of alkaline hydroelectrolysis hydrogen production system was established by using Aspen Plus software.The unknown parameters in the voltage model were fitted by using the test data of electrolytic cell by MATLAB software,and the correlation between the simulated values and the tested values was verified.The influence factors of electrolytic voltage and efficiency were analyzed by using the two models,and it was determined that the optimization of the electrolytic cell should focus on reducing the activation overpotential.Based on the model analysis results,this paper designed and built the alkaline hydroelectrolysis hydrogen production system.Firstly,the factors affecting the separation efficiency of the gas-liquid separator were studied by using the computational fluid dynamics simulation method,and the size of the separator was determined by the simulation calculation.Through the process calculation,the fluid conveying pipeline and the lye circulating pump were selected,and on this basis,the lye heat exchanger was designed and checked by Aspen EDR software.In order to ensure the safe operation of the system,the equipment selection and control scheme of the liquid level,pressure and temperature adjustment system were also made in this paper,and the design and construction of the whole hydrogen production system was finally completed.In order to expand the range of operating load of hydrogen production system,this paper uses the established alkaline hydrolysis hydrogen production system to analyze and study the influencing factors of gas purity.Through experimental tests,the lye flow or system pressure values that make gas purity meet the requirements under the conditions of various current densities are determined,and they are simulated into the form of synthetic relations and imported into the controller.The variation of hydrogen content in oxygen with current density was measured by setting a control scheme with flow-pressure following load variation in the scenario of current density step change to simulate the fluctuation of renewable energy,and compared with the corresponding change in the traditional operation mode.The results show that the control scheme can effectively improve the operating load range of alkaline hydroelectricity system.