Counter-flow diverging microchannels for heat sink
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Solution Overview
Problem
Current microchannel heat sinks face challenges with high heat flux dissipation due to low critical heat flux, temperature non-uniformity, and flow instability, particularly in large heating areas, which limits their effectiveness in cooling high-power electronic devices like electric vehicle components.
Innovation Solution
The use of counter-flow diverging microchannels with a unique heat exchange design between neighboring channels, where the microchannels have a diverging angle of between zero and 1°, enhances heat transfer performance by increasing the channel wall area to base area ratio, leading to higher heat dissipation rates, more uniform temperature distribution, and reduced pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional co-current flow microchannels are used, then the structure is simple, but the heat transfer coefficient is low and temperature uniformity is poor
Solution Approach 1:
The patent inverts the conventional co-current flow arrangement by implementing counter-flow configuration where adjacent microchannels have opposite flow directions. This inversion enables lateral heat exchange between channels, significantly improving temperature uniformity across the heating surface while maintaining a relatively simple microchannel structure.
Solution Approach 2:
The patent introduces lateral heat exchange between adjacent microchannels as a new dimension of heat transfer. By utilizing the wall area between channels for inter-channel heat exchange in addition to the primary heat transfer from the heating surface, the system achieves enhanced temperature uniformity without substantially increasing structural complexity.
2Productivity
If microchannel heat sink is used for high heat flux dissipation, then heat transfer area is increased, but critical heat flux is low and flow instability occurs
Solution Approach 1:
The counter-flow configuration inverts the conventional approach by having adjacent channels flow in opposite directions. This creates a stabilizing effect where the cooler outlet of one channel provides lateral cooling to the inlet region of the adjacent channel, suppressing bubble formation and flow instability while maintaining high heat dissipation capacity.
Solution Approach 2:
The lateral heat exchange between counter-flow channels provides preliminary cooling to regions where bubbles tend to form and accumulate. By pre-cooling the inlet regions of channels through lateral heat transfer from adjacent channel outlets, the system prevents premature boiling and flow instability before they can develop.
3Productivity
If diverging microchannels with larger angle are used, then bubble expansion is improved, but channel wall area to base area ratio decreases
Solution Approach 1:
The counter-flow configuration compensates for the reduced wall area in diverging channels by utilizing lateral heat exchange between channels. The inverted flow arrangement ensures that heat is efficiently transferred through the reduced wall area by leveraging the temperature difference between adjacent channels, maintaining high heat dissipation performance despite the geometric constraints.
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
This configuration results in a significantly higher heat transfer coefficient, critical heat flux, and coefficient of performance, with a 45.1% increment in heat transfer coefficient and 73.8% reduction in pressure drop compared to conventional co-current flow designs, ensuring stable two-phase flow and efficient heat dissipation.
Implementation Method 1
adjacent microchannels accommodate flow of working fluid in opposite directions and are thermally coupled to each other to enable heat exchange between the corresponding adjacent microchannels
Implementation Method 2
convective boiling in a heat sink with microchannel arrays is a very promising solution for such high heat transfer performance
Implementation Method 3
utilizing latent heat through the liquid-vapor phase change
Implementation Method 4
each microchannel cross sectional area increases as the channel length progresses from an upstream end to a downstream end
Data Source
AI summary
The present invention provides a microchannel heat sink with plural microchannels, each having a respective inlet and outlet to permit flow, in particular two-phase flow, of a working fluid. The plural microchannels are arranged such that adjacent microchannels accommodate flow of working fluid in opposite directions and are thermally coupled to each other to enable heat exchange between the corresponding adjacent microchannels. In one aspect, a microchannel inlet is positioned at an angle (e.g., 90 degrees) with respect to its outlet. The plural microchannels define parallel longitudinal axes that are optionally arranged on the same plane and/or side-by-side in a single layer. Further, in one aspect, each microchannel cross-sectional area increases as the channel length progresses from an upstream end (e.g., adjacent to the inlet) to a downstream end (e.g., adjacent to the outlet) of the corresponding microchannel.