R410A在光管及强化管管外冷凝换热的数值研究

Numerical Simulation of Condensation Heat Transfer of R410A outside Smooth and Enhanced Tubes

本文采用流体体积法(Volume of Fluid, VOF)多相流模型和Lee相变模型对制冷剂在水平光管和强化管管外的冷凝换热进行了数值模拟。分析了水平光管和强化管外液膜的瞬时液膜流动特性,计算了不同工况下光管和强化管的冷凝液膜厚度,及其与局部冷凝传热系数及管外冷凝传热系数的关系,并对不同制冷剂在相同工况下进行了比较。结果表明:模拟结果与实验数据和Nusselt解析解具有良好一致性,误差均在10%以内;局部传热系数大小对液膜厚度的分布非常敏感,且强化管管外冷凝传热系数约是光管的6倍;结合冷凝液膜的分布和制冷剂物性参数可得R410A的管外冷凝系数最高,而R1234yf则最低。

This paper adopted the volume of fluid(VOF)multiphase model and Lee phase transformation model to simulate the condensing heat transfer of coolants outside smooth and enhanced tubes.The in-stantaneous film flow characteristics of the liquid film outside the horizontal smooth and enhanced tubes were analyzed,and the thickness of the liquid film and the relationship with the local condensing heat transfer coefficient(HTC)and the condensing HTC outside the smooth and enhanced tubes under differ-ent working conditions were calculated.Different coolants were compared under the same working condi-tion.The results show that the simulation results are in good agreement with the experimental data and the Nusselt analytical solution,and the error is all within 10%;the distribution of liquid film thickness is highly sensitive to the magnitude of local condensing heat transfer coefficients,and the condensation HTC outside the enhanced tube is approximately six times of that of smooth tube;combining the distribution of the liquid film and the thermophysical property parameters of the coolants,it is determined that R410A has the highest HTC,while R1234yf has the lowest one.