Abstract
The research project MODEM — Next-generation multiscale MOdelling of Dense EMulsions for enhanced multiphase flow processes aims to advance the fundamental understanding and predictive modeling of dense liquid–liquid emulsions for application to a wide range of industrial multiphase processes. Dense emulsions, involving two immiscible liquid phases dispersed at high volume fractions, are encountered in critical operations such as petroleum extraction and transport, chemical production, food and pharmaceutical manufacturing, and liquid–liquid separations. Despite their ubiquity and importance, their behavior remains difficult to predict because of the complex, multiscale mechanisms at play, including turbulence, droplet deformation and interactions, interfacial phenomena influenced by surfactants, and the emergence of non-Newtonian rheology at higher concentrations. MODEM addresses these challenges through an integrated multiscale strategy that combines advanced experiments, high-fidelity simulations at different scales, and robust modeling approaches that bridge the gap between microscale droplet physics and macroscale process conditions. As part of this project, dedicated experiments and advanced numerical modeling were carried out to develop a comprehensive framework for describing the dynamics, distribution, and rheology of dense emulsions in laboratory-scale stirred tanks, with the aim of enabling predictive modeling transferable to industrial conditions. The experimental effort focused on a model system consisting of water and silicone oil emulsions prepared and dispersed in a 10-liter, fully baffled cylindrical tank equipped with a Rushton turbine. A wide range of operating conditions was explored, covering dispersed-phase volume fractions from very dilute (0.1%) up to dense regimes (10%), three impeller speeds corresponding to fully turbulent flow regimes, and three silicone oils differing in viscosity (2, 10, and 100 cSt). Such broad parametric coverage allowed for systematic assessment of the roles of phase fraction, fluid viscosity ratio, and energy dissipation in shaping the emulsion behavior. Drop size distributions (DSDs) were measured using a laser diffraction system. To overcome the detection limitations typical of optical techniques at higher concentrations, a dedicated protocol was developed to ensure robust and reproducible measurements across all regimes. In the experimental campaign, particular attention was devoted to the accuracy and reliability of the drop size distribution measurements, given the challenges posed by high dispersed-phase fractions and the risk of artifacts. A custom-designed sampling protocol was developed to withdraw liquid samples from the tank without entraining air, which could otherwise lead to spurious bubble detection in the laser diffraction measurements. To this end, a dedicated sampling system was designed and tested, incorporating 3D-printed components specifically shaped to minimize air entrainment when the liquid volume in the tank decreased during withdrawal. This precaution was crucial, as the presence of even small amounts of air bubbles would make it impossible to distinguish them from dispersed liquid droplets in the measurement, thus compromising the integrity of the data. Additionally, the dynamics of the wet cell of the laser diffraction instrument were carefully studied. This cell contains a small impeller that recirculates the liquid mixture through the optical measurement zone. Extensive tests were conducted to identify the optimal impeller speed: a speed too high could disrupt the DSD, either by breaking larger droplets or by entraining air, while a speed too low could allow larger droplets to segregate from the bulk mixture and escape detection. The chosen operating point for the wet cell impeller represented a compromise that ensured both homogeneity of the mixture and preservation of the intrinsic DSD. Fu
Project details
Unibo Team Leader: Alessandro Paglianti
Unibo involved Department/s:
Dipartimento di Chimica Industriale "Toso Montanari"
Coordinator:
Università degli Studi di NAPOLI Federico II(Italy)
Total Unibo Contribution: Euro (EUR) 50.631,00
Project Duration in months: 24
Start Date:
28/09/2023
End Date:
28/02/2026
