填料润湿性对CH4-C2H6-CO2流动传热影响的分子动力学模拟

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

  • 摘要: 在精馏填料塔中,传热传质过程主要发生在填料区域,填料润湿性对流动传热有显著影响。通过分子动力学模拟,研究了CH4-C2H6-CO2三元流体在填料微小通道内的流动与传热过程,重点分析了不同填料表面润湿性对流动与传热特性的影响。研究结果表明,填料表面润湿性显著影响通道内流体的温度分布、速度分布及分子层结构。润湿性越强,通道壁面对流体的作用力越大,近壁面区域的分子分布更为集中,温度梯度减小,固液界面处的温度阶跃和速度滑移量均有所降低,从而强化了通道内壁面与流体的热传导过程,但增大了流体阻力。研究从微观分子层面揭示了润湿性对流动与传热过程的影响机理,为LNG工业中优化低温精馏脱碳工艺提供了理论支持。

     

    Abstract: 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.

     

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