Using underground hydrogen storage technology has been recognized as an effective way to store hydrogen on a large scale, yet the physical mechanisms of hydrogen flow in porous media remain complex and challenging. Studying the heterogeneity of pore structures is crucial to enhance the efficiency of hydrogen storage. In order to better understand the pore-scale behavior of hydrogen in underground heterogeneous porous structures, this paper investigates the effects of wettability, pore–throat ratio, and pore structure heterogeneity on the behavior of the two-phase H₂–brine flow using pore-scale simulations. The results show that the complex interactions between wettability, heterogeneity, and pore geometry play a crucial role in controlling the repulsion pattern. The flow of H₂ is more obstructed in the region of the low pore–throat ratio, and the obstructive effect is more obvious when adjacent to the region of the high pore–throat ratio than that when adjacent to the region of the medium pore–throat ratio. In high-pore–throat ratio structures, the interfacial velocity changes abruptly as it passes through a wide pore and adjacent narrower throat. Interfacial velocities at the local pore scale may increase by several orders of magnitude, leading to non-negligible viscous flow effects. It is observed that an increase in the pore–throat ratio from 6.35 (low pore–throat ratio) to 12.12 (medium pore–throat ratio) promotes H₂ flow, while an increase from 12.12 (medium pore–throat ratio) to 23.67 (high pore–throat ratio) negatively affects H₂ flow. Insights are provided for understanding the role of the heterogeneity of pore structures in H₂–brine two-phase flow during underground hydrogen storage.

With the miniaturization of current electronic products, ceramic/polymer composites with excellent thermal conductivity have become of increasing interest. Traditionally, higher filler fractions are required to obtain a high thermal conductivity, but this leads to a decrease in the mechanical properties of the composites and increases the cost. In this study, silicon nitride nanowires (Si₃N₄NWs) with high aspect ratios were successfully prepared by a modified carbothermal reduction method, which was further combined with AlN particles to prepare the epoxy-based composites. The results showed that the Si₃N₄NWs were beneficial for constructing a continuous thermal conductive pathway as a connecting bridge. On this basis, an aligned three-dimensional skeleton was constructed by the ice template method, which further favored improving the thermal conductivity of the composites. When the mass fraction of Si₃N₄NWs added was 1.5 wt% and the mass fraction of AlN was 65 wt%, the composites prepared by ice templates reached a thermal conductivity of 1.64 W·m⁻¹·K⁻¹, which was ~ 720% of the thermal conductivity of the pure EP (0.2 W·m⁻¹·K⁻¹). The enhancement effect of Si₃N₄NWs and directional filler skeletons on the composite thermal conductivity were further demonstrated through the actual heat transfer process and finite element simulations. Furthermore, the thermal stability and mechanical properties of the composites were also improved by the introduction of Si₃N₄NWs, suggesting that prepared composites exhibit broad prospects in the field of thermal management.