温度对有机物传热影响的分子动力学模拟及微观机理研究

热导率是表征物质导热性能的一个重要物性参数.通过分子模拟从微观角度揭示有机物分子液体导热机理并计算热导率具有重要的理论意义和应用价值.通过非平衡态分子动力学模拟方法，分别模拟了庚烷、己醛、2-己酮和己醇在263～363 K的热传导过程并得到了热导率.4种有机物在263～363 K下热导率的计算值与实验值的相对平均偏差分别小于5.40%,5.46%,4.29%和7.80%,表明模拟结果与实验结果基本一致.热流分解和原子热路径的结果表明，对总热流有显著贡献的库仑相互作用项、范德华相互作用项和扭转角项都随着温度的升高而减小，这使得4种有机物的热导率随着温度的升高而降低.同时研究表明温度的升高增大了分子的原子振动，加速了分子运动，降低了模拟体系的质量密度.本文为温度对液体热传导影响提供了微观解释和理论依据.

Molecular dynamics simulation and microscopic mechanism study on the effect of temperature on heat conduction of liquid organic

Thermal conductivity is an important physical parameter to characterize the heat conduction of a substance. It is of great theoretical significance and application value to reveal the heat conduction processes mechanism and calculate the thermal conductivity of organic molecules by molecular simulation. In this paper, the thermal conductivity of heptane, hexanal, 2-hexanone and hexanol at 263~363 K were simulated by the non-equilibrium molecular dynamics (NEMD) simulation, and the corresponding thermal conductivities were calculated. The relative mean deviations were less than 5.40%, 5.46%, 4.29% and 7.80%, respectively, indicating that the simulation results were basically consistent with the experimental results. The results of the heat flux decomposition and atomic heat path indicate that the Coulomb interaction term, van der Waals interaction term and torsion angle term, which contribute significantly to the total heat flux, all decrease with increasing temperature, which makes the thermal conductivities of the four organics decrease with increasing temperature. It is speculated that the increase in temperature enlarges the atomic vibrations of molecules, accelerates the molecular motion, and decreases the mass density of the simulated system, which causes the above changes in the thermal conductivities of the four organic species.