表面张力对膜状凝结换影响研究

The Effect of the Interfacial Force to the Condensation

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.

This paper investigated the heat transfer process in the circular pipe and then analysed the effect of the gravity, the shearing force at the gas-liquid interface and the marangoni strength caused by the surface tension on the Nusselt numbier. In this paper, both physical model which include the condensation fluid film and mathematical model based on the boundary layer equation were founded and then transformed to 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 can 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.