Nanosecond Laser-Textured Copper Surfaces Hydrophobized with Self-Assembled Monolayers for Enhanced Pool Boiling Heat...

Area of Science:

• Materials Science
• Heat Transfer Engineering

Background:

• Compact systems with high heat fluxes require advanced cooling solutions like immersion cooling.
• Pool boiling is a key technique for high-performance heat transfer, but requires optimized surfaces.

Purpose of the Study:

• To investigate the effect of laser-textured surface microstructures on pool boiling heat transfer.
• To functionalize copper surfaces with varying structures and wettabilities for enhanced heat dissipation.

Main Methods:

• Developed three surface structures (crosshatch, shallow channels, deep channels) on copper using nanosecond laser texturing.
• Tested surfaces in both superhydrophilic and superhydrophobic states after applying a fluorinated silane.
• Evaluated boiling performance using water as coolant under saturated atmospheric conditions for three consecutive runs.

Main Results:

• All functionalized surfaces showed improved boiling heat transfer compared to untreated surfaces.
• The highest critical heat flux (1697 kW m⁻²) was achieved on a hydrophobized shallow-channel surface.
• A heat transfer coefficient enhancement of 775% was recorded on a hydrophobized deep-channel surface due to reduced bubble departure diameter and effective vapor entrapment.

Conclusions:

• Surface microstructure, particularly channel depth and hydrophobicity, is critical for enhancing pool boiling performance.
• Hydrophobized surfaces can achieve high critical heat flux values, challenging traditional assumptions.
• Optimized surface functionalization offers a promising route for advanced thermal management solutions.