相间传质对气泡聚并过程影响的实验研究

Experimental Study on the Effect of Interfacial Mass Transfer on Coalescence of Gas Bubbles

设计了一套双气泡聚并实验系统,考察了相间传质对气泡聚并过程的影响,气相采用非相变的N2,液相为挥发性的丙酮和乙醇水溶液.利用该系统测定了25?50℃温度下,不同组分浓度、鼓泡频率和气泡直径时气泡的聚并特性.结果表明,相间传质诱导的Marangoni效应使聚并时间随温度升高呈先减小后增大的趋势,聚并时间的分散性在较高温度下显著增大,采用聚并效率描述气泡聚并特性更合适;聚并效率在温度升高到一定程度后开始降低并趋于最小值,该值随溶液浓度增加而减小,稳定因子可定量描述Marangoni效应;鼓泡速率和气泡直径增加1倍,最小聚并效率分别减小50%和67%.

A two-bubble coalescence experimental system was set up to study the effect of interfacial mass transfer on coalescence process of gas bubbles with non-phase change N2 gas phase and volatile aqueous solutions of acetone and ethanol as liquid phase. The coalescence behavior was investigated under different volatile components, concentrations, bubbling frequencies and bubble diameters in the temperature range of 25？50 ℃. The results showed that because of the Marangoni effect induced by the interfacial mass transfer, the coalescence time decreased at first and then increased with increasing of temperature, the distribution of coalescence time was significantly increased at higher temperatures, and the coalescence percentage was now the best physical magnitude to describe the whole coalescence process. The coalescence percentage began to decrease when the temperature rose to a certain value and tended to be stable at a minimal value at higher temperatures, the minimal coalescence percentage decreased with increasing of aqueous solution concentration, and the intensity of Marangoni effect could be well quantified by the stabilizing index M. Doubling the bubbling frequency and bubble diameter would decrease the minimal coalescence percentage 50% and 67%, respectively.