Understanding condensation in microchannels is critical for designing optimized and compact microchannel condensers, which have the potential to increase system level efficiency and reduce system size. Analytical and numerical models can yield insights into local condensation phenomena. This study provides a review of models of condensation in microchannels. These models are categorized based on the applicable, typically annular and intermittent, flow regimes. Annular-flow-based models are further subdivided into analytical models with closed-form solutions, analytical models with numerical solutions, reduced-order CFD models, and full-fledged CFD models. Intermittent-flow-based models are subdivided into single-bubble, repeated-unit-cell, and overall-bubble-train models. The characteristics, use, and range of applicability of each of these models is highlighted. A criterion for the film Reynolds number is proposed for internal forced convective condensation in microchannels, to assess the validity of the modeling assumptions. Annular flow models using the laminar film assumption appear to be valid for Re_δ0 < ~ 360, beyond which turbulent effects must be modeled. Intermittent flow models using the laminar film assumption, in turn, appear to be valid for Re_δ0 < ~ 130.

了解微通道中的冷凝对于设计优化的紧凑型微通道冷凝器至关重要，冷凝器具有提高系统级效率和减小系统尺寸的潜力。分析和数值模型可以深入了解局部凝结现象。这项研究综述了微通道中的冷凝模型。这些模型基于适用的（通常为环形和间歇性）流动状态进行分类。基于环流的模型进一步细分为具有闭式解的分析模型，具有数值解的分析模型，降阶CFD模型和完全CFD模型。基于间歇流的模型可分为单气泡模型，重复单元气泡模型和整体气泡训练模型。特点，用途，并突出显示了每种模型的适用范围。提出了膜雷诺数的准则，用于微通道内的内部强制对流冷凝，以评估建模假设的有效性。使用层流膜假设的环形流动模型对于Re似乎是有效的_δ0 < _〜360，超出此范围必须建立湍流效应模型。反过来，使用层流膜假设的间歇流动模型似乎对_Reδ0 < _〜130有效。