微重力下三角形微通道内冷凝换热分析

摘要

采用VOF模型和自定义函数的方法对三角形微通道内冷凝换热特性进行了数值模拟研究.为验证模型的合理性,将计算得到的传热系数与文献中经验关联式的结果进行对比.分析了重力和表面张力对气液界面分布和传热性能的影响.结果表明,重力对微通道内气液界面分布和截面平均传热系数的影响很小.表面张力在非圆形微通道内的冷凝过程中发挥主导作用.在表面张力作用下,更多的冷凝液流向尖角,使壁面附近液膜厚度变薄,传热阻力减小,传热系数增强.%Numerical simulations of condensation heat transfer in triangle microchannels are presented.The model is established on the Volume of Fluid (VOF) approach and the user-defined routines which includes heat transfer at the vapor-liquid interface and latent heat.The predictive accuracy of the numerical model is assessed by comparing the heat transfer coefficient with the available empirical correlations in the literature.The influence of gravity and surface tension on the liquid-vapor interface distribution and heat transfer performance are analyzed.No obvious effect of the gravity is observed in the liquid-vapor interface distribution and the average cross sectional heat transfer coefficient.Surface tension,which plays a dominate role during the condensation in non-circular microchannels,leading to reduction of the condensate film thickness at the sides of the channel and accumulation of the condensate at the corners of the channel,giving rise to smaller thermal resistance and better heat transfer performance.