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Study on the Effect of a Sudden Jump in Wettability on Two-Component Liquid Flow in Sudden Contraction Devices
Pushpender Chaudhary1, Sumana Ghosh1
1Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667, India.
Langmuir : the ACS Journal of Surfaces and Colloids
|July 16, 2024
Summary
This study shows that hydrophobic surfaces upstream and hydrophilic surfaces downstream maximize liquid-liquid extraction efficiency. This configuration, combined with area changes, enhances extraction through specific flow patterns and recirculation zones.
Area of Science:
- Chemical Engineering
- Fluid Dynamics
- Separation Processes
Background:
- Liquid-liquid extraction is crucial for chemical separation processes.
- Understanding the impact of surface wettability and flow area changes is vital for optimizing extraction efficiency.
- Existing research often overlooks the combined effects of wettability and geometric transitions.
Purpose of the Study:
- To experimentally investigate how surface wettability and sudden changes in flow area influence liquid-liquid extraction.
- To determine the optimal arrangement of hydrophilic and hydrophobic surfaces for maximum extraction efficiency.
- To elucidate the underlying flow physics responsible for enhanced extraction using computational fluid dynamics (CFD).
Main Methods:
- Experimental setup involving interconnected hydrophilic (glass) and hydrophobic (PTFE-coated) capillaries with varying wettability arrangements.
- Utilizing acetic acid, toluene, and water as test fluids to observe different flow patterns (slug, droplet, etc.).
- Employing open CFD software (OpenFoam) for numerical simulations to analyze flow dynamics at the area change interface.
Main Results:
- Maximum extraction efficiency was achieved with a hydrophobic tube upstream followed by a hydrophilic tube downstream.
- The specific surface area of the slug flow increased by 1.6 to 2.7 times due to the contraction in flow area.
- CFD simulations revealed a recirculating zone downstream of the area change, promoting encapsulated drop formation and enhancing slug circulation.
Conclusions:
- Surface wettability, particularly the upstream hydrophobic configuration, significantly impacts liquid-liquid extraction performance.
- Sudden changes in flow area, combined with wettability gradients, create favorable conditions for enhanced mass transfer.
- The observed flow phenomena, including recirculating zones and encapsulated drops, are key to understanding and improving extraction efficiency in such systems.
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