Physical property recommendations for computational modeling of water electrolysis

Green hydrogen is necessary for the production of many low-carbon fuels. Water electrolysis is the most developed technology for green hydrogen. Process simulations and multiphysics models are widely used in industry. With an accurate model, scientists and engineers can direct research efforts or give recommendations for investing in technologies or companies. For models to give meaningful results, it is essential that the thermophysical properties of the materials in the system be represented correctly. Without correct property data, models will be inaccurate even if the underlying physics is precisely captured. However, increasing accuracy in physical properties can increase the computational cost of modeling. This report reviews the available literature for fluids present in most modern electrolyzers at industrially important conditions: water, hydrogen, oxygen, aqueous potassium hydroxide, and their mixtures. The report then reviews the current best data and practices for estimating density, heat capacity, thermal conductivity, surface tension, electrical conductivity, solubility, and electrical conductivity while balancing accuracy and computing speed. These properties are reviewed for pure components and mixtures in both liquid and vapor phases. Additional experimental data for these properties is necessary as the energy industry adopts green hydrogen production, but the recommendations made here are the best available at the time of the report.