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首页> 外文期刊>Experimental Heat Transfer >MOLECULAR-LEVEL MODELING OF INTERFACIAL PHENOMENA IN BOILING PROCESSES
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MOLECULAR-LEVEL MODELING OF INTERFACIAL PHENOMENA IN BOILING PROCESSES

机译：沸腾过程中界面现象的分子水平建模

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The thermophysics of liquid-vapor interfaces has long been recognized as a critical element in the physical mechanisms of boiling processes. This article will describe results of recent molecular dynamics simulation studies that explore the structure and stability of liquid-vapor interfacial regions using a hybrid analysis scheme that combines new formulations of capillarity theory with molecular dynamics simulations that use similar interaction potentials. Two forms of this type of hybrid scheme have been developed: one for non-polar fluids based on a Lennard-Jones interaction potential and a second specifically for water using a modified treatment of the extended simple point charge interaction potential that accounts for water dipole interactions. The hybrid model has the advantage that the capillarity theory provides theoretical relationships among parameters that govern interfacial region structure and thermophysical behavior, while the companion molecular dynamics simulations allow more detailed molecular level exploration of the interfacial region thermophysics. Predictions of interfacial region structure indicated by this kind of hybrid modeling will be described for pure non-polar and water liquid-vapor interfaces and for water with dissolved ionic solutes (i.e., salts). Extension of the methodology to thin liquid films will also be described. Rupture of a free liquid film dictates merging of adjacent bubbles, which is particularly important in nucleate boiling heat transfer, bubbly two-phase flow in small tubes, and the mechanisms that dictate the Leidenfrost transition. To understand the mechanisms of bubble merging in nanostructured boiling surfaces and in nanotubes, it is useful to explore film stability and the onset of rupture at the molecular level. Results obtained with the hybrid model indicate that wave instability predominates as an onset of rupture mechanism for free liquid films of macroscopic extent, but for free liquid films with nanoscale lateral extent (e.g., in nanostructured boiling surfaces), lack of film core stability is more likely to be the mechanism. Predictions of the hybrid models will be compared to results of experimental studies of the effects of ionic solutes on interfacial tension and bubble merging. The implications of the molecular dynamics model predictions for boiling processes in micro-channels and boiling in nanostructured surfaces are also discussed.
机译：长期以来，人们一直认为液体-蒸汽界面的热物理是沸腾过程物理机制中的关键要素。本文将描述最近的分子动力学模拟研究的结果，该研究使用混合分析方案探索液汽界面区域的结构和稳定性，该方案将毛细管理论的新公式与使用相似相互作用势的分子动力学模拟相结合。已经开发出两种形式的这种混合方案：一种用于基于Lennard-Jones相互作用势的非极性流体，另一种用于水，使用扩展的简单点电荷相互作用势的修正处理来解决水，这解释了水偶极相互作用。混合模型的优势在于，毛细作用理论提供了控制界面区域结构和热物理行为的参数之间的理论关系，而伴随分子动力学模拟允许对界面区域热物理进行更详细的分子水平探索。对于纯的非极性和水液体-蒸汽界面以及具有溶解的离子溶质（即盐）的水，将描述这种混合模型所指示的界面区域结构的预测。也将描述该方法对液体薄膜的扩展。自由液膜的破裂指示相邻气泡的合并，这在成核的沸腾传热，小管中的气泡两相流以及决定莱顿弗罗斯特转变的机理中尤其重要。为了了解气泡在纳米结构沸腾表面和纳米管中合并的机理，探讨膜的稳定性以及在分子水平上破裂的发生是很有用的。混合模型获得的结果表明，对于宏观范围的自由液体薄膜，波动不稳定性是破裂机制的主要起因，但是对于具有纳米级横向范围的自由液体薄膜（例如，在纳米结构的沸腾表面），缺乏膜芯稳定性的可能性更大。可能是机制。混合模型的预测将与离子溶质对界面张力和气泡合并的影响的实验研究结果进行比较。还讨论了分子动力学模型预测对微通道沸腾过程和纳米结构表面沸腾过程的影响。

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