Loading...

Molecular Dynamics Simulation of Fluid-Fluid and Solid-Fluid Interactions in Underground Hydrogen Storage

Haghighatnejad, Yasaman | 2025

0 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58021 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Mahani, Hassan; Ayatollahi, Shahaboddin; Pourkhiabani, Nahid; Esmaeilbeig, Mohammad Amin
  7. Abstract:
  8. Hydrogen is recognized as a clean energy carrier, playing a crucial role in energy transition. Subsurface formations, such as aquifers with large storage capacities, present economically viable options for hydrogen storage. However, optimizing the storage and recovery of hydrogen depends significantly on the wetting behavior of surfaces under various conditions. Determination of the wetting properties under different conditions is challenging due to experimental limitations, safety concerns, and the time required for tests, all of which can impact the efficiency of the process. For this reason, limited data are available in the published literature on the wettability of hydrogen-brine-calcite systems. On the other hand, molecular simulations can provide insights into the mechanisms of rock and fluid interactions, as well as the influence of dissolved salts, facilitating the design of subsequent experiments and measurements. In this study, molecular dynamics (MD) simulations were performed using LAMMPS software to investigate the impact of brine salinity and composition (sodium chloride and potassium chloride) on the interfacial tension between hydrogen and brine, as well as the wetting behavior of various calcite surfaces, including the 104 and 001 planes with both positive and negative charges, in the presence of hydrogen and brine. Simulations were conducted at a temperature of 373 K and a pressure of 250 bar with salt concentrations of 0.1 M and 1 M for both types of salts. The results were analyzed from a molecular perspective using various methods, including radial distribution functions, potential energy evaluations, density profiles, and analysis of hydrogen bonds. The findings indicate that the interfacial tension between hydrogen and brine increases with salinity and is not sensitive to salt type. For the contact angle of water droplets in the presence of hydrogen on the 104 calcite surface, regardless of brine salinity or cation type, the contact angle is zero, indicating highly hydrophilic behavior of this cleavage. This characteristic facilitates spreading and formation of a stable water film on the surface. With increasing salt concentration, more hydrogen molecules dissolve in the water layer. The distribution of hydrogen molecules near calcite surfaces was influenced by brine composition and salinity. Moreover, it is observed that, at 0.1 M salinity, hydrogen molecules distribute in the solution with distances higher than 4 Å from the calcite surface, while higher salinities resulted in distributions higher than 7 Å with sodium chloride and 12 Å with potassium chloride. This specific interaction indicates the potential for geochemical reactions between hydrogen and the calcite surface over time, which could alter wetting properties. To assess the effect of surface chemistry and charge, tests were conducted on the 001 plane with negative and positive charges. For the negatively charged 001 plane, contact angles at low salt concentrations were approximately 51∘ for sodium chloride and 45∘ for potassium chloride. With increasing salinity, these angles increased to about 72∘ for both salts, indicating that the hydrophilicity of the negatively charged calcite surface decreases with higher salt concentrations, primarily due to changes in hydration dynamics. Simulations with the positively charged 001 plane show that a 0.1 M potassium chloride solution result in a contact angle of 20∘, while other systems exhibit zero contact angles. This suggests that at a 0.1 M potassium chloride concentration, the surface exhibits lower hydrophilicity compared to other conditions. Additionally, brines containing potassium chloride at 0.1 M showed significantly higher hydrogen accumulation compared to other systems near the surface
  9. Keywords:
  10. Underground Hydrogen Storage ; Surface Wettability ; Molecular Dynamic Simulation ; 001 Calcite Surface ; 104 Calcite Surface ; Hydrogen Recovery

 Digital Object List

 Bookmark

No TOC