Thermodynamic modeling of hydrogen–water systems with gas impurity at various conditions using cubic and PC-SAFT equations of state

• Published in: Energy conversion and management. X 2022-08, Vol.15, p.100257, Article 100257
• Main Authors: Alanazi, Amer, Bawazeer, Saleh, Ali, Muhammad, Keshavarz, Alireza, Hoteit, Hussein
• Format: Article
• Language: English
• Subjects: equation of state (EoS); fuel cells; hydrogen impurity; Hydrogen storage; hydrogen-water; solubility; water vaporization
• ISSN: 2590-1745; 2590-1745
• DOI: 10.1016/j.ecmx.2022.100257

[Display omitted] •Comparison of two advanced equations of state in predicting vapor-liquid equilibria of H2–water mixtures.•Optimizing binary interaction coefficients using regression against experimental data.•Calculating the H2–water solubility using flash liberation modeling and flowsheet simulation.•Modeling results of both equations of state depict good agreement with experimental data.•Demonstrating the capability of SR-RK in predicting the influence of gas impurity in H2 feed. Hydrogen (H2) has emerged as a viable solution for energy storage of renewable sources, supplying off-seasonal demand. Hydrogen contamination due to undesired mixing with other fluids during operations is a significant problem. Water contamination is a regular occurrence; therefore, an accurate prediction of H2-water thermodynamics is crucial for the design of efficient storage and water removal processes. In thermodynamic modeling, the Peng–Robinson (PR) and Soave Redlich–Kwong (SRK) equations of state (EoSs) are widely applied. However, both EoSs fail to predict the vapor-liquid equilibrium (VLE) accurately for H2-blend mixtures with or without fine-tuning binary interaction parameters due to the polarity of the components. This work investigates the accuracy of two advanced EoSs: the Schwartzentruber and Renon modified Redlich–Kwong cubic EoS (SR-RK) and perturbed-chain statistical associating fluid theory (SAFT) in predicting VLE and solubility properties of H2 and water. The SR-RK involves the introduction of polar parameters and a volume translation term. The proposed workflow is based on optimizing the binary interaction coefficients using regression against experimental data that cover a wide range of pressure (0.34 to 101.23 MPa), temperature (273.2 to 588.7 K), and H2 mole fraction (0.0004 to 0.9670) values. A flash liberation model is developed to calculate the H2 solubility and water vaporization at different temperature and pressure conditions. The model captures the influence of H2-gas (CO2) impurity on VLE. The results agreed well with the experimental data, demonstrating the model’s capability of predicting the VLE of hydrogen-water mixtures for a broad range of pressures and temperatures. Optimized coefficients of binary interaction parameters for both EoSs are provided. The sensitivity analysis indicates an increase in H2 solubility with temperature and pressure and a decrease in water vaporization. Moreover, the work demonstrates the capability of SR-RK in