The Effect of Packing Wettability on CH₄-C₂H₆-CO₂ Flow and Heat Transfer: A Molecular Dynamics Study

In a distillation packed column, the process of heat and mass transfer primarily occur within the packing region, where the wettability of the packing material significantly influences convective heat transfer. This study employs molecular dynamics simulations to investigate the flow and heat transfer processes of a ternary fluid system consisting of methane, ethane, and carbon dioxide within the microchannels of packing materials. The focus is on analyzing how different wettability characteristics of the packing surfaces affect the flow and heat transfer properties of the fluid.By comparing the simulation results with existing literature and standard data from the National Institute of Standards and Technology（NIST）, the molecular interaction potential suitable for the CH₄-C₂H₆-CO₂ ternary system has been validated. The research results indicate that, influenced by molecular mass and molecular interaction forces, the three types of molecules exhibit different therma diffusivities and thermal conductivities, ranked from highest to lowest as CH₄, C₂H₆, and CO₂. The wettability of the packing surfaces has a profound impact on the temperature distribution, velocity distribution, and molecular layering within the channel. Specifically, stronger wettability leads to greater interaction forces between the fluid and the channel walls, resulting in a more concentrated molecular distribution near the wall region. This concentration effect reduces the temperature gradient, as well as the hydrodynamic and thermal slip at the solid-liquid interface, thereby enhancing the heat transfer process between the channel walls and the fluid. However, this increased wettability also leads to higher fluid resistance. By revealing the underlying mechanisms through which wettability influences flow and heat transfer at the microscopic molecular level, this research provides valuable theoretical support for optimizing low-temperature distillation and decarbonization processes in the liquefied natural gas （LNG） industry.