Manipulating Droplet Dynamics for Enhancing Dropwise Condensation on the Ultra-Slippery Hydrophilic Surface

Area of Science:

• Surface Science and Engineering
• Heat Transfer and Thermodynamics
• Materials Science

Background:

• Ultraslippery hydrophilic (US-HI) surfaces are crucial for energy and water applications due to their droplet mobility.
• Understanding droplet dynamics on these surfaces is key to enhancing condensation heat transfer.
• Existing surfaces face limitations in droplet mobility and efficient renewal.

Purpose of the Study:

• To prepare a US-HI surface with ultralow contact angle hysteresis for efficient dropwise condensation.
• To quantitatively investigate the dynamic characteristics of condensed droplets on the prepared US-HI surface.
• To compare the condensation performance of the US-HI surface with state-of-the-art surfaces.

Main Methods:

• Grafting PEG silane onto a substrate to create an ultraslippery hydrophilic surface.
• Quantitative investigation of droplet dynamics: growth, coalescence, contact line migration, and size distribution.
• Comparison of condensation heat transfer efficiency with other advanced surfaces.

Main Results:

• The US-HI surface exhibited ultralow contact angle hysteresis, minimizing nucleation energy and sliding resistance.
• Droplets on the US-HI surface grew and coalesced an order of magnitude faster than on conventional surfaces.
• Droplet departure and renewal were 24.8% more efficient, leading to higher microdroplet density and enhanced heat transfer, surpassing superhydrophobic surfaces.

Conclusions:

• The developed US-HI surface significantly enhances droplet mobility and condensation efficiency.
• High-frequency droplet departure is critical for maximizing dropwise condensation heat transfer.
• The findings provide insights for designing advanced surfaces for efficient phase-change processes in energy and water management.