Liquid Drawdown: Scalability Over Several Geometries

• Author / Creator

  Safari-alamuti,Fatemeh

• This work examined liquid/liquid drawdown. Two tank geometries (ST and CIST) and three sets of impellers (PBT, A310, RT) were used. Water and Canola oil were the continuous and dispersed phases, respectively, with a holdup of oil of either 10% or 30%. First, the point of initial disruption of the interface (Nid) and the point where the complete drawdown of oil into water occurred (Ncd) were determined. Then the time (tcd) required to completely disperse the surface layer at Ncd and the power consumed (P) were measured, from which the mixing energy (Jcd=P·tcd) was calculated. In a second set of experiments, focused beam reflectance measurement (FBRM) was used to measure the transient chord length distribution (CLD) at Ncd and equilibrium time (teq) and the transient Sauter mean chord length (cl32) were determined. Scaling results showed that the cl32 at tcd scaled well with Jcd/m. Data also showed that the energy/cl32 correlation was independent of geometry and holdup when all impellers started the run in the continuous phase. Unlike energy, power per mass showed no clear trend with Sauter mean chord length. In addition, Ncd and tcd were not scalable with power per mass. The results suggest that mixing energy is a useful scaling variable across several geometries. Comparison of cl32 with the Kolmogorov scale (η) showed that the area weighted CLD falls above the Kolmogorov scale, while half of number weighted CLD is smaller than η. This observation is supported by recent studies of drop break-up based on tip streaming and a renewed interest in satellite drops.

• Subjects / Keywords

  • liquid mixing, draw down, scalability

• Graduation date

  Spring 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3V40KF0V

• License

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