湿空气掠过竖直壁面的凝结换热研究

Research of humid air condensation heat transfer across the vertical wall

为讨论湿空气凝结速率各种计算公式和忽略凝结液膜对换热的影响,通过对湿空气的凝结特点分析,采用数值计算方法研究了湿空气掠过竖直冷壁面时的热量和质量传递规律.探讨了温度、速度和浓度对气液相界面法向速度和湿空气凝结质量传递速率的影响,得出了湿空气凝结计算公式的实用条件.发现冷壁面温度是影响对流传质的决定性因素,当壁面温度大于310 K时,对流传质量占总传质量的5%。与理论关联式对比表明,在所研究范围内忽略较薄的凝结液对计算结果产生的误差不大于1%.

Numerical methods were used to study the heat and mass transfer characteristics of humid air across a vertical cold wall,based on the analysis of the humid air condensation,to discuss equations applied for condensation mass flux of humid air and the assumption of neglecting thin condense on heat transfer.Discussions were made on the effects of temperature,velocity and concentration of humid air on the interface velocity normal to cold wall and condensation mass flux of humid air.The practicable conditions for these humid air condensation equations were obtained.Results indicated that the temperature of plate surface was the decisive factor of advective mass flux and the advective mass transfer could reach 5% of the total mass transfer for wall temperature of 310 K.The assumption of neglecting thin condense was proved to produce error of less than 1% during present study.