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Freezing Patterns of Supercooled Binary Droplets on Cold Hydrophobic Surfaces
Faquan Shen1, Wen-Zhen Fang1, Shengyun Zhang1
1Key Laboratory of Thermo-Fluid Science and Engineering of MOE, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China.
Langmuir : the ACS Journal of Surfaces and Colloids
|September 26, 2025
Summary
This study reveals four freezing patterns in water-ethanol droplets on hydrophobic surfaces, driven by ethanol concentration and subcooling. A theoretical model accurately predicts freezing times based on ethanol content.
Area of Science:
- Materials Science
- Fluid Dynamics
- Chemical Engineering
Background:
- Binary droplet freezing is crucial for industrial applications like aerospace and manufacturing.
- Understanding water-ethanol droplet behavior on cold surfaces is essential for process optimization.
Purpose of the Study:
- To investigate the freezing patterns of water-ethanol binary droplets on cold hydrophobic surfaces.
- To establish a phase diagram correlating freezing patterns with ethanol concentration and subcooling.
- To develop a theoretical model for predicting droplet freezing time.
Main Methods:
- Utilized high-speed and infrared imaging for droplet visualization.
- Employed Hele-Shaw cell for in-situ observation of freezing dynamics.
- Developed a theoretical model based on the Stefan problem.
Main Results:
- Identified four distinct freezing patterns: incomplete freezing, localized bulge, dispersed bulge, and no bulge.
- Established a phase diagram showing the dependence of freezing patterns on ethanol concentration and subcooling.
- Observed sustained freezing point depression due to ethanol accumulation at the freezing front.
- Validated a theoretical model that accurately predicts freezing time based on ethanol concentration.
Conclusions:
- Freezing patterns are governed by the interplay between ethanol migration velocity and freezing front propagation velocity.
- Ethanol concentration significantly influences droplet freezing behavior and freezing time.
- The developed theoretical model provides a reliable tool for predicting freezing dynamics in binary droplet systems.
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