Tapered Microchannel Flow Field for Low-Pressure Boiling Cooling
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Solution Overview
Problem
Current microchannel designs for electronics cooling face challenges with high pressure drops, flow instability, low critical heat flux, and low heat transfer coefficients during flow boiling, which limit their effectiveness in dissipating high heat fluxes without significant increases in pumping power.
Innovation Solution
A heat transfer system with a tapered flow field cross-sectional area, incorporating open enhancement features from 1 micron to 3 mm in height, which reduces pressure drop and enhances heat transfer by providing an escape path for vapor during boiling and promoting liquid flow towards the heat transfer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If microchannels with small hydraulic diameters are used for heat transfer, then heat transfer efficiency is improved, but pressure drop increases significantly
Solution Approach 1:
The patent applies parameter changes by varying the hydraulic diameter along the flow direction, transitioning from small diameters at the inlet (for high heat transfer coefficient) to larger diameters at the outlet (for reduced pressure drop). This gradual parameter change optimizes both heat transfer efficiency and pressure drop characteristics throughout the channel length.
Solution Approach 2:
The patent implements dynamics by making the channel geometry variable rather than constant. The hydraulic diameter dynamically changes along the flow direction, allowing the system to adapt to different flow conditions and thermal requirements at different locations, thereby resolving the contradiction between heat transfer efficiency and pressure drop.
2Temperature
If surface features such as roughness, corrugations, and fins are added to enhance heat transfer, then heat transfer coefficient is improved, but pressure drop increases
Solution Approach 1:
The patent applies local quality by introducing surface features only in specific regions where they are most effective, rather than uniformly across the entire channel. The variation in channel geometry allows for localized enhancement of heat transfer while minimizing the overall impact on pressure drop by concentrating features in regions of higher velocity or temperature gradient.
3Ease of manufacture
If constant cross-sectional area channels are used, then manufacturing is simplified, but heat transfer uniformity deteriorates due to temperature variation along the coolant stream
Solution Approach 1:
The patent applies parameter changes by varying the cross-sectional area along the flow direction to compensate for temperature variations. By increasing the cross-sectional area in regions where temperature rises, the coolant can absorb heat more effectively, maintaining more uniform temperature distribution across the chip surface while still using relatively simple manufacturing techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tapered flow field design achieves higher heat transfer coefficients and critical heat fluxes while maintaining lower pressure drops, enabling efficient heat dissipation with reduced temperature non-uniformity and increased heat transfer surface area.
Implementation Method 1
The increased pressure drop leads to higher pumping power, increased fluid pressure, and a steep pressure gradient in the channels along the flow direction
Implementation Method 2
a substrate in fluid communication with the fluid inlet and fluid outlet, the substrate includes a heat exchange region having a heat transfer surface
Implementation Method 3
flowing fluid to the fluid inlet, through the flow field and out the fluid outlet in a manner to transfer heat in the heat exchange region
Implementation Method 4
the flow field heat transfer region includes a plurality of open enhancement features from about 1 micron to about 3 mm in height
Data Source
AI summary
A heat transfer system including a fluid inlet; a fluid outlet; and a substrate in fluid communication with the fluid inlet and fluid outlet, the substrate including a heat exchange region having a heat transfer surface and a flow field adjacent the heat transfer surface, the flow field including a fluid flow area including an open region at the inlet, a heat transfer region in thermal communication with the heat exchange region, and a taper of the flow field cross-sectional area in the flow direction, wherein the flow field heat transfer region includes a plurality of spaced apart open enhancement features from 1 micron to 3 mm in size, and method for enhancing the heat transfer performance of an apparatus is disclosed.