Nanoparticle-Assisted Pool Boiling Heat Transfer on Micro-Pin-Fin Surfaces

Area of Science:

• Heat Transfer
• Fluid Dynamics
• Materials Science

Background:

• Boiling heat transfer intensification is critical for energy conversion and cooling systems.
• FC-72 (a dielectric liquid) is commonly used in electronics cooling applications.
• Surface modifications are explored to enhance heat transfer performance.

Purpose of the Study:

• To enhance saturated pool boiling of FC-72 using micro pin fin structures and copper nanoparticles.
• To investigate the underlying mechanisms responsible for heat transfer enhancement.

Main Methods:

• Fabrication of circular and square micro pin fins on silicon surfaces via dry etching.
• Deposition of copper nanoparticles onto micro pin fin surfaces using electrostatic deposition.
• Experimental analysis including high-speed bubble visualization, surface wickability measurements, and model analysis.

Main Results:

• Micro pin fins increased heat transfer coefficient by over 200% and critical heat flux by 65-83% compared to a smooth surface.
• Copper nanoparticles further enhanced heat transfer coefficient by up to 24% and critical heat flux by over 20%.
• High heat transfer coefficients correlated with small bubble departure diameters and high departure frequencies.

Conclusions:

• Surface modifications with micro pin fins and nanoparticles effectively intensify boiling heat transfer.
• Surface wickability is crucial for critical heat flux, alongside bubble evaporation dynamics.
• Optimized surface structures and materials can significantly improve cooling efficiency in electronic devices.