This paper deals with the condensation heat transfer characteristic of propane (R290) inside a 4-mm-inner-diameter (ID) horizontal smooth tube. Three-dimensional Computational Fluid Dynamics (CFD) simulations were performed based on the volume of fluid (VOF) multiphase flow model and shear stress transport (SST) k-ω turbulence model together with a dedicated user-defined function (UDF) compiled for the phase change model. The flow pattern and velocity field distribution were derived, and the condensation heat transfer coefficient (HTC) versus mass flux, saturation temperature, and heat transfer temperature difference were analyzed in detail. The results demonstrate that the area-weighted average condensation HTC of the wall takes on an average increase rate of 33.69% as the mass flux increases from 180 to 360 kg/(m² s), and an average decrease rate of 19.83% with the increasing saturation temperature. Besides, the local condensation HTC swells more than twice as the temperature difference increases from 5 to 20 K. Compared with the saturation temperature, the mass flux and heat transfer temperature difference have a more remarkable effect on the condensation flow pattern and velocity field distribution. Under the specific conditions, the flow condensation of R290 inside the tube can be successively transformed from annular flow, annular wavy flow, half annular flow to plug flow, and the annular flow region can be enlarged with increasing mass flux. Comparing the simulated results with those of the experiment, it can be concluded that the numerical model adopted in this paper has good accuracy and the relative deviation is within ± 20%.

本文讨论了 4 毫米内径 (ID) 水平光滑管内丙烷 (R290) 的冷凝传热特性。基于流体体积 (VOF) 多相流模型和剪切应力传递 (SST) k-ω进行三维计算流体动力学 (CFD) 模拟湍流模型以及为相变模型编译的专用用户定义函数 (UDF)。推导出流型和速度场分布，并详细分析冷凝传热系数 (HTC) 与质量通量、饱和温度和传热温差的关系。结果表明，随着质量通量从180增加到360 kg/(m ²s)，随着饱和温度的升高，平均下降率为 19.83%。此外，随着温差从 5 增加到 20 K，局部冷凝 HTC 膨胀两倍以上。与饱和温度相比，质量通量和传热温差对冷凝流型和速度场分布的影响更为显着。在特定条件下，R290在管内的流动凝结可以依次由环状流、环状波状流、半环状流向活塞流转变，环状流区域可以随着质量流量的增加而扩大。将模拟结果与实验结果进行比较，可以得出本文采用的数值模型具有较好的精度，相对偏差在±20%以内。