Kinetics of Drop Breakage in Stirred Vessels under Turbulent Conditions

Abstract

The emulsification of dodecane oil was studied in a standard stirred vessel filled with distilled water. The in situ size distribution of the drops was measured at certain time intervals by using a particle size analyzer while stirring. The results showed that an increase in the stirring time and stirring rate resulted in a decrease in the mean drop size of drops and shifted the drop size distribution toward smaller sizes. The minimum droplet size in the turbulent flow was found to be proportional to a min (WD) 21.75 . Normalization of data exhibited that the size distribution of drops is self-preserving. The distribution of mean drop size and distribution functions of drops were determined by using models developed from the Focker-Plank equation regarding size distribution of particles in turbulent flows. The evaluation of droplet breakage with time in isotropic turbulent flow showed that the size distribution can be represented by the summation of log-normal distribution function in series. It was found that the experimental data could be represented well by the empirical models.

Emulsification in turbulent flow

“…[33,34], an effective breakage rate constant was determined from the observed decrease of the mean drop size with the emulsification time in stirred tanks. The experimental results were described by an empirical equation, which included several adjustable constants.…”

Testing fireproof materials in a combustion chamber

“…At this moment, is due to the complexity of solved task necessary to rely on literature, which is based on empirically verified and tested data [6,7,11,12]. After a thorough study of this issue is using and adjusting of these parameters advisable to tweak the simulation nearer the experiment.…”

“…This statistical model is suitable for description of materials composed of huge number of small particles like powder, emulsion and in our case small gas particles. More about using of this technique could be read there [12,13,18]. At the other side, perhaps, due to the highly complicated model linked with a number of various boundary conditions and big concentration of the gas particles inside a relative small place (chamber), does not this parameter of used statistical approach seems to be as much important to the final results.…”

“…For proper adjustment of the model, especially in the definition of reaction media (air, gas), is very important come out of the fundamentals of chemistry, which defines the bonding forces [6,11] and formed particles. The final model of gaseous components presented by particles participating in the reaction and their statistical distribution is described by [12,13]. So the whole problem goes beyond simple mechanical definitions of material properties and boundary group members (geometry).…”

Review on Measurement Techniques for Drop Size Distribution in a Stirred Vessel

“…Fast measurements also allow this technique to detect changes in drop size when there is a change in the dispersion process, such as varying impeller speed. 9 Online monitoring of drop size distributions in an agitated vessel using a Malvern Mastersizer has been conducted by Chatzi et al 25 and Sis et al 33 Sis et al 33 applied the instrument for in situ measurement of dodecane in water (see Table 1) emulsion in turbulent flow. It is achieved by placing the flow-through cell in the path of the light beam of the light scattering device.…”