Comparative Study of Mathematical Models for Describing the Distribution of Hydrogen-Enriched Natural Gas in Enclosed Spaces

This study focuses on the investigation of stratification phenomena during the transportation and storage of hydrogen-enriched natural gas (HENG) in enclosed spaces. Two mathematical models, namely, the species transport model and the multiphase mixture model, are commonly used to describe the stratification phenomena of HENG. To evaluate the suitability of both models in simulating the stratification phenomena of HENG, the model accuracy was initially validated by comparing with published experimental data. Subsequently, the spontaneous concentration distribution trend in a binary gas mixture (hydrogen + methane) system within an enclosed space is analyzed based on the principles of minimum energy. The findings indicate that the species transport model is more suitable for describing the distribution of HENG in enclosed spaces; the HENG mixture gradually attains uniform concentration distribution when it remains static and eventually reaches equilibrium without any obvious concentration stratification. This study aims at offering valuable insights for ensuring safe transportation and storage of HENG.