论文标题
液体碳氢化合物体在泰坦的溶解度和表面吸附的压力和温度依赖性
Pressure and temperature dependence of solubility and surface adsorption of nitrogen in the liquid hydrocarbon bodies on Titan
论文作者
论文摘要
我们使用了甲烷和乙烷中氮混合物的二元混合物的蒸气平衡模拟氮和乙烷在甲烷和乙烷中的溶解度的压力和温度依赖性，以在1.5 atm和3.5 atm和3.5 atm和温度之间的一系列压力之间，在90 K和110 K和110 K，110 K和110 K，热力学条件之间，可能存在于Saturn titan上。我们发现，氮在甲烷中的溶解度随压力随压力而增加，而乙烷中氮的溶解度则随温度90 K的压力而呈指数增加。甲烷和乙烷在甲烷和乙烷中的溶解度在3 atm的压力下均表现出与温度的指数降低。与此处研究的压力和温度范围内的乙烷相比，甲烷中氮的溶解度要大得多。我们的结果与氮和乙烷中氮的溶解度的可用实验测量有定量一致。此外，我们发现，氮的表面吸附在温度90 K时的压力增加，而吸附自由能随压力增加而增加。此外，我们发现表面张力会随着氮 - 甲烷和氮 - 乙烷系统的压力而线性降低。与氮 - 甲烷系统相比，氮 - 乙烷系统的压力下表面张力的降低速度要大得多。最后，我们发现氮分子从界面吸收到液相中是扩散的，并且不涉及任何明显的能屏障。我们的结果表明，气泡的均匀成核不太可能在泰坦上，而泰坦湖中的气泡形成必须来自气泡的异质成核。
We have studied the pressure and temperature dependence of solubility of nitrogen in methane and ethane using vapor-liquid equilibrium simulations of binary mixtures of nitrogen in methane and ethane for a range of pressures between 1.5 atm and 3.5 atm and temperatures between 90 K and 110 K, thermodynamic conditions that may exist on the Saturn's moon, Titan. We find that the solubility of nitrogen in methane increases linearly with pressure while the solubility of nitrogen in ethane increases exponentially with pressure at temperature 90 K. Solubility of nitrogen in both methane and ethane exhibits an exponential decrease with temperature at a pressure of 3 atm. The solubility of nitrogen in methane is much larger compared to that in ethane in the range of pressure and temperature studied here. Our results are in quantitative agreement with the available experimental measurements of the solubility of nitrogen in methane and ethane. Furthermore, we find that the surface adsorption of nitrogen increases with increasing pressure at temperature 90 K, while the adsorption free energy increases with increasing pressure. Moreover, we find that the surface tension decreases linearly with pressure for both nitrogen-methane and nitrogen-ethane systems. The rate of decrease of surface tension with pressure for nitrogen-ethane system is much larger as compared to the nitrogen-methane system. Finally, we find that the absorption of a nitrogen molecule into the liquid-phase from the interface is diffusive and does not involve any appreciable energy barrier. Our results suggest that homogeneous nucleation of bubbles is unlikely on Titan and the bubble formation in the lakes on Titan must arise from heterogeneous nucleation of bubbles.
