• 作者： Wu, Wuu-Tsann; Hu, Chih-Lun; Yang, Yu-Min
• 中文摘要： 雖然已知某些微量界面活性劑會顯著地促進水的核沸騰熱傳速率,可是其促進機構目前仍不清楚。本文以管狀沸騰面進行sodium lauryl sulfate水溶液的池式沸騰實驗。測定沸騰啟始所需的過熱度,並以高速攝影技術研究汽泡成長的動態。實驗結果顯示:沸騰啟始過熱度.DELTA.T/sub incip/,隨界面活性劑的添加而顯著地降低。此一結果可以文獻上的理論模式,考慮表面張力和接觸角的變化,合理地解釋。另一方面,添加界面活性劑會促使汽泡週期t/sub c/和等待時間t/sub w/,顯著地減小,但會使得成長時間t/sub g/,稍微延長。同時,添加界面活性劑會使汽泡明顯變小。界面活性劑水溶液中,汽泡等待時間的減小,也可以文獻上的理論模式,考慮表面張力和接觸角的變化,合理地解釋。然而,與汽/液界面的動態有關的沸騰汽泡成長行為,便無法以文獻上現有的理論方程式描述。有關界面活性水溶液中汽泡成長的動態,有進一步研究的必要。
• 英文摘要： Small amount of certain surfactants in aqueous solution has been known to significantly enhance the rate of nucleate boiling heat transfer. The mechanism of this enhancement has, however, still remained unclear. Boiling incipience and vapor bubble growth dynamics of aqueous surfactant solutions of sodium lauryl sulfate at identified sites were studied in this work in a pool boiling apparatus with tubular heater by determining the incipient superheat and by high speed photography. Incipient superheat,.DELTA.T/sub incip/, shown from the experimental results to have significantly decreased by the addition of surfactant. This occurrence would be reasonably explained by taking into consideration the surface tension depression and contact angle change in a theoretical prediction. On the other hand, the addition of surfactant caused period, t/sub c/, and waiting period, t/sub w/, to become drastically shorter, and also caused growth period, t/sub g/, to become slightly longer. In the meantime, addition of surfactant caused bubble size to become considerably smaller. The shorter waiting period of surfactant solution would also be reasonably explained by taking into consideration the surface tension and contact angle changes in a theoretical prediction. However, boiling behavior of surfactant solution was observed to be insufficiently described by existing equations from previous literature as long as dynamic vapor- liquid interface is involved. Further studies on bubble growth dynamics would be needed.
• 中文關鍵字： 沸騰; 汽泡成長; 界面活性劑; 熱傳遞; 表面張力; 接觸角
• 英文關鍵字： Boiling; Bubble Growth; Surfactant; Heat Transfer; Surface Tension; Contact Angle