Fundamental mathematical model of electrochemical hydrogen compressor

Electrochemical hydrogen compressors have shown great potential in widening hydrogen usage, but further research is still needed to increase their efficiency and hydrogen output pressure. A novel fundamental mathematical model of the compressor is made in MATLAB/Simulink, which is validated with published experimental results and compared with previous models. The model provides a better understanding of the compressor's operating mechanism, which is described through equations based on laws of physics and electrochemical relations for four different voltages from 0.025 V to 0.1 V. Achieved output pressures in model simulations reach values from 6.8 bar to 257 bar, respectively. In comparison with other models' results, these results account for Nernst potential, activation and ohmic overpotentials, and hydrogen back diffusion losses, simulated as time functions. Also, valuable insight into the dynamics of remaining parameters that influence the compressor's performance is provided based on different values of applied potential difference, operating temperature, membrane water content, and membrane thickness. The simulation affirms that one of the main pressure-limiting issues is hydrogen back diffusion due to pressure differences between the electrodes, while the optimization of the compressor's performance is a trade-off between wanted output parameters, mainly, voltage and current efficiency. The model can be used to optimize the electrochemical hydrogen compressor's performance based on the demand such as, e.g., defined nominal pressure and nominal output hydrogen flow. Thus, a multi-criteria optimization process can be defined later on that leads to an optimized compressor which ensures given nominal values of needed parameters. © 2024 Elsevier Ltd