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Experimental Investigation of Dropwise Condensation Shedding by Shearing Airflow in Microgravity Using Different
Milad Shakeri Bonab1, Christoph Minetti2, Carlo Saverio Iorio2
1Department of Mechanical Engineering, York University, Toronto, OntarioM3J 1P3, Canada.
Langmuir : the ACS Journal of Surfaces and Colloids
|December 27, 2022
Summary
In microgravity, aerodynamic forces shed water droplets at lower velocities than on Earth, especially from hydrophobic surfaces. Droplet size and surface properties significantly influence shedding dynamics in condensation systems.
Area of Science:
- Fluid dynamics
- Heat transfer
- Materials science
Background:
- Dropwise condensation is key for efficient heat transfer.
- Aerodynamic forces are crucial for droplet shedding in microgravity for life support systems.
- Surface properties influence droplet adhesion and removal.
Purpose of the Study:
- Investigate water droplet shedding kinematics under aerodynamic forces in microgravity.
- Determine the effect of surface coatings and droplet size on shedding.
- Compare shedding behavior in microgravity versus normal gravity.
Main Methods:
- Studied shedding of water droplets (40-80 μL) on four surfaces (PMMA, PS, PTFE, SHS) under aerodynamic forces.
- Conducted experiments in both microgravity and normal gravity environments.
- Analyzed critical shedding velocities and droplet detachment phenomena.
Main Results:
- Critical shedding velocity in microgravity was up to 8% lower than in normal gravity.
- Shedding velocity decreased with increasing droplet size in both gravity conditions.
- Enhanced surface hydrophobicity reduced critical shedding velocity.
- Droplets detached from superhydrophobic surfaces in microgravity.
Conclusions:
- Lower critical velocities in microgravity necessitate adjustments for condensing heat exchangers.
- Droplet detachment in microgravity can impede condensation efficiency and dehumidification processes.
- Surface engineering is vital for optimizing droplet removal in space-based condensation systems.
