Cai Shouyin, Li Qibin, Liu Chao, Zhang Lu
Key Laboratory of Low-grade Energy Utilization Technologies & Systems, Ministry of Education, College of Energy and Power Engineering, Chongqing University, Chongqing, 400044, P. R. China.
Phys Chem Chem Phys. 2020 Jul 22;22(28):16157-16164. doi: 10.1039/d0cp02808h.
Evaporation is a typical heat and mass transfer process, which is important in both nature and industry. Here, the evaporation of five fluid samples (pure Ar, pure Kr and Ar/Kr mixtures with molar ratio Ar : Kr = 1 : 3, Ar : Kr = 1 : 1 and Ar : Kr = 3 : 1) on Pt surface was investigated using molecular dynamics simulations. Colligative properties of the mixtures led to the melting of the Ar/Kr mixtures (Ar : Kr = 1 : 1, Ar : Kr = 3 : 1) at 70 K below the triple point of Ar. Furthermore, under the same condition, the other systems were frozen as the solid state. The Pt surface at 90 K, over the boiling point of Ar, triggered the evaporation of Ar atoms in all the systems while the Kr atoms remained in the condensed state. Kr atoms were reported to be evaporated to a large extent when the Pt surface was heated to 120 K near the boiling point of Kr. The presence of Kr could reduce the evaporation of the Ar atoms, especially when the mole ratio of Ar : Kr in the mixture was 1 : 1 because the Ar : Kr = 1 : 1 system can effectively reduce the temperature of the gas-liquid interface. The temperature of the fluid samples then decreased with increase in distance between Pt and fluid atoms because the evaporated atoms could take the thermal energy away from the condensed films. Moreover, both Ar and Kr atoms, which were close to the Pt surface, hardly changed during evaporation because of the strong attractive force from the Pt substrate.
蒸发是一种典型的传热传质过程，在自然界和工业中都很重要。在此，使用分子动力学模拟研究了五种流体样品（纯氩、纯氪以及摩尔比为氩∶氪 = 1∶3、氩∶氪 = 1∶1和氩∶氪 = 3∶1的氩/氪混合物）在铂表面的蒸发情况。混合物的依数性导致氩/氪混合物（氩∶氪 = 1∶1、氩∶氪 = 3∶1）在低于氩三相点70 K时熔化。此外，在相同条件下，其他系统则冻结为固态。90 K的铂表面高于氩的沸点，引发了所有系统中氩原子的蒸发，而氪原子则保持凝聚态。据报道，当铂表面加热到接近氪沸点的120 K时，氪原子会大量蒸发。氪的存在会减少氩原子的蒸发，尤其是当混合物中氩∶氪的摩尔比为1∶1时，因为氩∶氪 = 1∶1的系统可以有效降低气液界面的温度。然后，流体样品的温度会随着铂与流体原子之间距离的增加而降低，因为蒸发的原子会带走凝聚膜的热能。此外，由于来自铂基底的强大吸引力，靠近铂表面的氩原子和氪原子在蒸发过程中几乎没有变化。
