Acoustic Microchannel Boiling Surface for Stable Electronic Cooling
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Solution Overview
Problem
Flow boiling in microchannels experiences instabilities and dynamic local dry-out phenomena at high heat-flux levels, leading to inefficient heat transfer due to limited vapor bubble nucleation sites and system-level instabilities.
Innovation Solution
A cooling module with micro-structured boiling surfaces and piezoelectric transducers is used to enhance vapor bubble nucleation and detachment by directing acoustic waves on the boiling surface, increasing nucleation site density and stabilizing the flow boiling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flow boiling is implemented in microchannels at high heat-flux levels, then heat transfer capacity is improved, but flow instabilities and dynamic local dry-out phenomena occur
Solution Approach 1:
The patent applies ultrasonic vibration to the heating surface to mechanically disrupt vapor bubble formation and prevent dry-out phenomena. The vibration causes the heating surface to oscillate at high frequency, which prevents vapor accumulation and maintains liquid contact with the heating surface, thereby improving reliability while maintaining high heat transfer capacity.
Solution Approach 2:
The patent employs periodic ultrasonic cycles to alternately promote and suppress vapor bubble formation. During specific phases of the ultrasonic cycle, vapor bubbles are enhanced for heat transfer, while during other phases, the vibration disrupts bubble coalescence and prevents dry-out. This periodic action resolves the contradiction between achieving high heat transfer and maintaining flow stability.
2Productivity
If vapor bubble nucleation sites are increased on the heating surface, then heat transfer efficiency is improved, but system complexity increases
Solution Approach 1:
The patent replaces complex mechanical surface structures with a simpler smooth heating surface that utilizes ultrasonic vibration to create transient nucleation sites. Instead of manufacturing complex micro-structures on the heating surface, the system uses acoustic fields to dynamically create and control vapor bubble formation, thereby improving heat transfer efficiency without increasing structural complexity.
Solution Approach 2:
The patent changes the operational parameters of the heating surface by applying ultrasonic frequency vibrations. This dynamic parameter change allows the same smooth surface to exhibit different nucleation characteristics at different phases of the ultrasonic cycle, effectively increasing nucleation site density without modifying the physical surface geometry.
3Productivity
If acoustic waves are directed on the boiling surface to enhance vapor bubble formation, then nucleation site density increases, but energy consumption increases
Solution Approach 1:
The patent utilizes the phase transition properties of the working fluid in conjunction with ultrasonic vibration. The acoustic energy is most effectively used during the phases when the fluid is transitioning between liquid and vapor states, amplifying the natural phase change process rather than continuously supplying energy. This allows high nucleation site density to be achieved with minimized energy input.
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 solution significantly improves heat transfer coefficients and cooling capacity by increasing vapor bubble formation and detachment rates, reducing temperature differences and enhancing heat flux handling capabilities compared to traditional flow boiling heat exchangers.
Implementation Method 1
a piezoelectric transducer...configured to direct acoustic waves on the micro-structured boiling surface
Implementation Method 2
direct acoustic waves on the micro-structured boiling surface
Implementation Method 3
facilitate formation of microbubbles within the heat transfer fluid at microbubble nucleation sites on the micro-structured boiling surface
Implementation Method 4
formation of microbubbles within the heat transfer fluid
Implementation Method 5
passing a heat transfer fluid through one or more channels formed in a cooling module body
Data Source
AI summary
A cooling module for an electronic device includes a body having formed therein a plurality of channels, a micro-structured boiling surface, a piezoelectric transducer, an inlet header, and an outlet header. Each channel of the plurality of channels is defined by a first channel surface and opposing lateral channel surfaces cooperatively defining a rectangular cross section normal to a channel axis. The micro-structured boiling surface is positioned adjacent the first channel surface of each channel. The piezoelectric transducer is in acoustic communication with one of the opposing lateral channel surfaces of each channel and configured to direct acoustic waves on the micro-structured boiling surface. The inlet header is in fluid communication with each channel of the plurality of channels. The outlet header is in fluid communication with each channel of the plurality of channels.