Simulation of a Pressurized Alkaline Water Electrolysis Electrolyzer Cell and Its System.

Abstract

Low-pressure hydrogen produced using alkaline water electrolysis (AWE) is typically stored and transported after pressurization using a compressor. However, the utilization of AWE in a pressurized electrolyzer to directly produce high-pressure hydrogen has the advantages of improving the AWE system efficiency, reducing energy consumption, and simplifying the system. This system is better integrated into large-scale hydrogen production and can reduce operation and maintenance costs. An AWE system model comprising a pressurized electrolyzer was established. This study developed a simulation model of an electrolyzer module that combines the physical and chemical fields to evaluate the impact of pressurization on the operation of the electrolyzer and the system. Subsequently, the optimal electrolysis conditions under various hydrogen pressures were predicted. The results showed that for the electrolyzer module, the Faraday efficiency first increased and then remained constant as the pressure for electrolyzing water increased, whereas hydrogen production increased. An increase in the electrolysis voltage resulted in an increase in the energy consumption of the electrolyzed water. The electrolysis efficiency and purity of the AWE system first increased and then gradually decreased, reaching a maximum value at a relative pressure of 5 bar when the electrolyzed water pressure increased. Under various demand-side hydrogen pressure requirements, the greater the demand-side pressure, the higher the optimal efficiency of the system corresponding to the electrolysis water pressure.