毛细管中泰勒流的流动及液相分散特性

Two-phase flow and axial liquid dispersion characteristics in single capillary Taylor flow

在竖直毛细管中以自来水为液相,氮气为气相,气液两相在泰勒流型操作范围内并流向上流动。采用CCD照相法获得流动参数,采用脉冲示踪法通过电导探针测定浓度-时间曲线。考察了表观气、液速对气含率、液栓长度、液相平均停留时间和轴向扩散系数的影响规律。结果表明,气含率在0.4～0.85间,随表观气速的增加而增大,随表观液速的增加而减小;液栓长度的范围是5～30 mm,其变化规律则与气含率的相反;液相平均停留时间在6～11 s,随着表观气、液速的增加而减小;轴向扩散系数的范围是20～110 cm2/s,随表观气、液速的增加而增大,轴向混合加大;本文建立的彼克莱数关联式Pe=2.214Re0.2εG-0.364ψ0L.948能够预测实验值,偏差在±20%以内。

Two-phase flow and axial liquid dispersion characteristics in a single capillary have been experimentally investigated by a charge-coupled device（CCD） imaging method and conductivity probes using a pulse tracer method,respectively.Liquid mean residence time,axial dispersion coefficient and hydrodynamic parameters were measured with tap water as the liquid phase and nitrogen as the gas phase in Taylor flow.It has been demonstrated that： gas holdup within a range of 0.4-0.85 increased with increasing superficial gas velocity and decreasing superficial liquid velocity;liquid slug length varied in the opposite sense in the range 5-30 mm;the mean residence time within the range 6-11 s decreased,and the axial dispersion ranging from 20-110 cm2/s increased when increasing either gas or liquid superficial velocity.A correlation of the Peclet number Pe=2.214Re0.2ε-0.364Gψ0.948L is presented and is able to predict the experimental data within a relative deviation of ±20%.