Department of Mechanical Engineering, California State University, Fresno, Fresno, California 93740, USA.
Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
J Chem Phys. 2018 Feb 14;148(6):064708. doi: 10.1063/1.5020095.
Using molecular dynamics simulations, we study evaporation and condensation of fluid Ar in the presence of a non-condensable Ne gas in a nanochannel. The evaporation and condensation are driven by the temperature difference, ΔT, between the evaporating and condensing liquid surfaces. The steady-state evaporation and condensation fluxes (J) are also affected by the Ne concentration, ρ, and the nanochannel length. We find that across a wide range of ΔT and ρ, J is in good agreement with the prediction from Stefan's law and from Schrage relationships. Furthermore, for ΔT less than ∼20% of the absolute average temperature, we find that both steady-state heat and mass fluxes are proportional to ΔT. This allows us to determine the interfacial resistance to the heat and mass transfer and compare it with the corresponding resistances in the gas phase. In this context, we derive an analytical expression for the effective thermal conductivity of the gas region in the nanochannel and the mass transport interfacial resistance equivalent length, i.e., the length of the nanochannel for which the resistance to the mass flow is the same as the interfacial resistance to the mass flow.
利用分子动力学模拟，我们研究了在纳米通道中非冷凝性 Ne 气体存在的情况下，流体 Ar 的蒸发和冷凝。蒸发和冷凝是由蒸发和冷凝液表面之间的温差 ΔT 驱动的。稳态蒸发和冷凝通量（J）也受到 Ne 浓度 ρ 和纳米通道长度的影响。我们发现，在广泛的 ΔT 和 ρ 范围内，J 与 Stefan 定律和 Schrage 关系的预测非常吻合。此外，对于 ΔT 小于绝对平均温度的约 20%，我们发现稳态热和质量通量都与 ΔT 成正比。这使我们能够确定界面处的热传递和质量传递阻力，并将其与气相中的相应阻力进行比较。在这种情况下，我们推导出了纳米通道中气体区域的有效导热系数和质量传输界面阻力等效长度的解析表达式，即质量流阻力与界面质量流阻力相同时的纳米通道长度。
