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Keywords:

  • bubble;
  • alcohol drops;
  • sunflower oil;
  • terminal velocity;
  • drag coefficient

Abstract

Steady rises of a single air bubble, a methanol drop, and an ethanol drop in a vertical glass column of refined sunflower oil at temperatures of 25, 30, 40, and 50°C are investigated experimentally using photography. The Reynolds numbers obtained are 0.07–16, 0.02–13.43, and 0.017–11.18 for the air bubbles, methanol drops, and ethanol drops, respectively. Results for terminal velocity and drag coefficient are compared with the selected existing correlations for bubble and drop motions in immiscible liquids. Correlations by Rodrigue show good agreement for various bubble sizes and system temperatures. Experimental drag coefficients of methanol and ethanol drops show a systematic deviation from the Oliver and Chung and the Darton and Harrison correlations, respectively. Considering the effect of dissolution of alcohol in vegetable oil, which varies with temperature, on the drop dynamics, semiempirical correction factors are applied to the last two correlations to fit the experimental results. © 2010 American Institute of Chemical Engineers AIChE J, 2011