Marangoni效应对圆管内膜状凝结的影响

Influence of Marangoni effect on film condensation inside a circular pipe

对圆管内膜状凝结换热过程进行了理论分析,探讨了重力、表面张力梯度引起的Marangoni力以及气液界面剪切力对凝结换热Nusselt数的影响。建立了含有凝结液膜的物理模型和基于边界层方程组的数学模型,应用相似理论进行了无量纲变换。结果表明,表面张力梯度对凝结换热过程的影响不可忽略,梯度越大,液膜越薄,Nu数越大,换热越好。

The heat transfer process in the circular pipe was investigated and the effect of the gravity, the shearing force at the gas-liquid interface and the Marangoni strength caused by the surface tension gradient on the Nusseh number were analyzed. Both physical model which included the condensation fluid film and mathematical model based on the boundary layer equation were founded and then transformed into a non-dimensional form by applying the similarity theory. The results showed that the effect of the surface tension gradient on the condensed heat process could not be ignored. The greater the gradient was, the thinner the liquid film was. The bigger the Nu number was, the better the effect of the heat transfer was.