Ultra-efficient Two-phase Evaporators/Boilers Enabled by Nano-tip-Induced Boundary Layers



Reference #: 01037

The University of South Carolina is offering licensing opportunities for nanotip-induced boundary layers to enhance flow boiling in microchannels.

Invention Description:

The subject invention describes a method to make boundary layers created by nanotip arrays fabricated along the walls of microchannels that suppress flow boiling instabilities and control two phase flows and heat transfer.

Potential Applications:

Energy-efficient and cost-effective two-phase cooling systems in next-generation high-power electronics, 3D microelectronics, and high power photonics

Advantages and Benefits:

1.  Alters and reduces flow boiling regimes to separate liquid and vapor flows

2.  Enhances heat transfer coefficient through thin film evaporation on the induced boundary layers, advections from high frequency rewetting, and improved nucleate boiling cavities created by the nanotips

3.  Greatly improves global liquid supply through a high frequency bubble growth and collapse process while improving local liquid supply by inducing capillary flow.

4.  Enhances critical heat flux using the liquid supply mechanism (#3) created by the induced boundary layer at global and local levels

5.  Drastically reduces pressure drop because of the separation of liquid and vapor flows and the lubrication effect of the induced boundary layer


Bubble confinements, viscosity, and surface tension force-dominated flows are all flow boiling constraints that cause unpredictable flow pattern transitions in microchannels and tend to induce severe two-phase flow instabilities and suppress evaporation and convection, which is detrimental to flow boiling heat transfer. These limit its application in cooling high power electronic and photonic components. As a result, two-phase microchannels have not been accepted as a practical approach for electronics cooling.

Testing and Development:

The impacts of nanotips-induced boundary layers (BL) were partially validated in a preliminary study. The velocity in the microchannels with induced BL was approximately an order of magnitude higher that in microchannels with smooth walls. Rapid rewetting induced by the nanotips was also observed in the preliminary study and observed to increase with increasing working heat flux.

Patent Information:
Title App Type Country Serial No. Patent No. File Date Issued Date Expire Date Patent Status
Ultra-Efficient Two-Phase Evaporators/Boilers Enabled by Nanotip-Induced Boundary Layers Utility United States 14/279,742 5/16/2014     Filed
For Information, Contact:
Technology Commercialization
University of South Carolina
Chen Li
Fanghao Yang
Yan Tong
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