摘要:
根据反射光谱可用于分析固体表面介质凝聚状态的原理,理论分析了不锈钢表面上不同厚度薄液膜对表面反射率的影响,确定了在冷凝过程中该表面上冷凝液形成和更新过程导致相应反射率变化的范围.通过分析滴状冷凝实验过程反射光谱的文献数据,研究了滴状冷凝过程壁面上蒸气分子凝聚特征,发现在实际的滴状冷凝传热过程中,液滴脱落后形成的裸露表面上存在反射特征介于液膜与体相蒸气分子之间的介质.结合蒸气冷凝过程的分子团聚模型,得到了在滴状冷凝过程中近壁面附近的蒸气分子形成分子团聚分布的合理性.此外,分析发现表面微观结构将改变团聚体分布密度,从而影响冷凝核化过程的现象.这为冷凝传热强化方法的研究提出了新的思路.
Abstract:
The clustering phenomenon on the solid wall during dropwise condensation is analyzed with reflection spectrum.By the theoretical prediction of reflectivity of thin liquid films with different thicknesses on the stainless steel surface,it is ascertained that the reflectivity value is corresponding to the coacervate character of the steam molecular.Furthermore,by analyzing the experimental data of the reflection spectrum during dropwise condensation,presented in the literature,it is obtained that the reflection character and so the coacervate character lies between liquid and steam after the droplet has fallen off during an actual continuous condensation process.And the clustering model is used to analyze the results,which point out that clusters are formed on the blank surface.And it is found that the different microstructures of the solid wall can lead to different deposition rates of the clusters,which presents an effective way to enhance the heat transfer process of condensation by guickening the deposition rate of clusters with the surface modification.
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