It is necessary to disclose the two-phase interphase behavior in the liquid desiccant dehumidifier/regenerator applicable for air conditioning, but the present investigation is far from enough. In this paper, the surface structure of liquid desiccant solution is analyzed by molecular dynamics simulations. LiBr-H₂O is chosen as the working solution with a concentration of 1 M and the system model is built with Gromacs. System temperatures vary from 300 to 350 K covering the temperature range of liquid desiccant dehumidification and regeneration. Density profiles of ions and water molecules are plotted along the vertical directions, and their distribution preferences on the solution surface are discussed. With the molecular simulation, it is found there is an ions-vapor layer with a thickness of 6–9 Å between the saturated vapor and bulk solution, which is not shown in the traditional macroscopic models. The results show that the density of water remains stable in the bulk while decreases sharply on the solution surface. However, the salt ions, i.e. Li⁺ and Br^-, have a peak density on the surface. This ions-vapor layer behaves like a buffer to transfer water molecules from/to the bulk solution. More research will be required to investigate how to control the ions-vapor layer, so that air dehumidification and solution regeneration can be easily operated, which provides significant energy savings for the liquid desiccant air conditioning.

中文翻译：

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空调液体干燥剂表面异常现象的分子研究

有必要披露适用于空调的液体干燥剂除湿器/再生器中的两相间相行为，但是目前的研究还远远不够。本文通过分子动力学模拟分析了干燥剂溶液的表面结构。溴化氢₂选择O作为浓度为1 M的工作溶液，并使用Gromacs构建系统模型。系统温度从300到350 K不等，涵盖了液体干燥剂除湿和再生的温度范围。沿垂直方向绘制了离子和水分子的密度分布图，并讨论了它们在溶液表面的分布偏好。通过分子模拟，发现在饱和蒸气与本体溶液之间存在一个厚度为6–9Å的离子-蒸气层，这在传统的宏观模型中没有显示。结果表明，水的密度在整体中保持稳定，而在溶液表面急剧下降。然而，盐离子，即李⁺和Br ^-在表面上具有峰值密度。该离子蒸汽层的行为就像缓冲剂一样，可以将水分子从大体积溶液中转移出来。需要进行更多的研究来研究如何控制离子-蒸汽层，以便可以轻松地进行空气除湿和溶液再生，从而为液体干燥剂空调节省大量能源。