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Published on: April 10, 2017
Light-responsive threadlike micelles as drag reducing fluids with enhanced heat-transfer capabilities.
Haifeng Shi1, Yi Wang, Bo Fang
1Department of Chemical and Biomolecular Engineering, Ohio State University, 140 West 19th Avenue, Columbus, Ohio 43210, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|April 23, 2011
Summary
Light-responsive surfactants with threadlike micelles can switch drag reduction on and off. This innovation improves heat transfer in recirculating systems by temporarily disabling drag reduction where needed.
Area of Science:
- Rheology and Fluid Dynamics
- Materials Science
- Photochemistry
Background:
- Drag-reducing (DR) surfactant fluids with threadlike micelles exhibit poor heat-transfer properties, limiting their application.
- Current limitations necessitate their use primarily in systems where heat exchange is not critical.
Purpose of the Study:
- To investigate light-responsive threadlike micelles as a solution for enhancing heat transfer in drag-reducing fluids.
- To demonstrate the ability to modulate drag reduction and heat transfer properties using light.
Main Methods:
- Utilized cationic surfactant Ethoquad O/12 PG (EO12) and sodium salt of trans-ortho-methoxycinnamic acid (OMCA).
- Investigated the effect of UV light exposure on micelle structure and fluid properties using cryo-transmission electron microscopy (cryo-TEM).
- Measured drag reduction and heat-transfer capabilities of the fluid before and after UV irradiation.
Main Results:
- Initially, fluids contained threadlike micelles, showing high viscoelasticity and up to 75% drag reduction.
- UV light exposure caused photoisomerization of OMCA, leading to micelle shortening and reduced viscoelasticity.
- UV-irradiated fluid exhibited significantly lower drag reduction but considerably superior heat-transfer properties.
Conclusions:
- Light-responsive threadlike micelles offer a method to switch off drag reduction, thereby enhancing heat transfer.
- This controllable property is ideal for optimizing heat exchangers in recirculating systems.
- Future work could explore photoreversible systems for dynamic control of both drag reduction and heat transfer.
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