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Evaluation of Exerted Drag Force on Alkane Saturated Air Bubbles in Aqueous Solutions by Experimental Studies

Rajabzadeh Dezfuli, Mehdi | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55531 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Bastani, Dariush; Lotfi, Marzieh
  7. Abstract:
  8. Interfacial phenomena and properties of interphase surfaces in dynamic mode play an important role in industrial processes that include gas-liquid and liquid-liquid multiphase flows. As well as, interface knowledge leads to better understanding of natural and fundamental phenomena. The present study has been performed for understanding about dynamic behavior of interphase surfaces in the presence of nanoparticles and hexane vapor in gas-liquid dispersion systems. In this research, rising bubble method has been used as one of the most conventional techniques. Accordingly, aqueous solutions of nanosilica were prepared in concentrations of 50, 100, 200, 400 and 1200 ppm as continuous phase fluid, and the movement of single air and hexane saturated air bubbles was investigated in these solutions. The results of the experiments reveal the presence of silica nanoparticles in the interface has both negative and positive effects on exerted drag. The negative effect is due to the movement and sliding of nanoparticles in the interface, which increases the surface friction, while the positive effect is related to the vibration of nanoparticles in their place on the interface, which causes an increase in the fluctuation and fluidity of the interface. In all of the nanosilica solution concentrations except for the concentration of 1200 ppm, the negative effect overcomes the positive effect, but in the solution of 1200 ppm the positive effect is more than the negative effect and the rising bubble velocity has been augmented. Hexene vapor eventually condenses on the interface, then an oily layer is formed on the interface. This oily layer makes the interface more slippery, but its effect is not noticeable. When the hexane oily layer and silica nanoparticles present at the gas-liquid interface simultaneously, the interface becomes remarkably more slippery. The best synergistic effect of hexene vapor and silica nanoparticles occurred at solution concentration of 200 ppm. In this concentration, terminal velocity and drag coefficient of the rising bubble increased and decreased by 6.53% and 12.5% compared to the rising air bubble in pure water, respectively. Furthermore, the obtained drag coefficients in this research were compared to the experimental models of other scholars, and it was concluded these models aren’t able to predict the drag coefficient of the rising bubble in a solution that contains impurities of the nanoparticle type
  9. Keywords:
  10. Rising Bubble ; Interfaces ; Drag Coefficient ; Silica Nanoparticles ; Hexane Vapor ; Drag Force ; Aqueous Solutions ; Terminal Velocity

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