微层蒸发模型的非平衡热力学分析

Non-equilibrium thermodynamic analysis of micro-layer evaporation model

基于非平衡热力学理论,以水的沸腾换热时的微层蒸发模型为例,采用国际上流行的IFC公式,对微层蒸发模型的汽泡内部的蒸汽温度分布进行了数值计算。结果表明,要完成微层蒸发模型中的蒸发和凝结两个相变过程,汽泡内部的蒸汽温度并非均匀的,由于汽泡的半径很小,从而导致在汽泡垂直方向上存在有极大的温度梯度,这就使得微层蒸发模型的合理性值得商榷,有必要进一步发展新的模型。

Based on the view point of non-equilibrium thermodynamic theory, taking the widely accepted and applied micro-layer evaporation model of water boiling heat transfer as an example, a numerical calculation for the temperature distribution in the bubble in heterogeneous boiling process was presented in this paper. The results show that an extremely high gradient of temperature along the vertical direction inside a small bubble must be required if there is △μ（=μ1- μv） 〉0 in the lower part of the bubble, but △μ in the upper. Calculation shows such a condition can hardly be realized and a new boiling heat transfer model is necessary to be developed. The study above provides a reference for the understanding of bubble behavior and mechanism of boiling heat transfer.