Micro-channel Pulsating Heat Pipe Embedded in Planar Substrates
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Solution Overview
Problem
Existing pulsating heat pipe devices are difficult to mount effectively, fragile, and challenging to manufacture, with limitations in thermal conductivity due to large tubing diameters and fewer bends/turns, making them unsuitable for high-performance applications like aerospace and microelectronics where efficient thermal regulation is critical.
Innovation Solution
Embedding micro-channels into solid-state structures using micro-fabrication technology, allowing for smaller diameter tubing, increased bends/turns, and precise fabrication, creating a robust and efficient thermal control system with improved thermal conductivity by forming serpentine micro-channel traces and alternating diameters for annular flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bent tubing is used to create pulsating heat pipes, then thermal control function is achieved, but mechanical robustness and ease of mounting deteriorate
Solution Approach 1:
The device is segmented into multiple thin planar layers (first planar layer, second planar layer) that are bonded together, replacing the continuous bent tubing structure. This segmentation allows each layer to be structurally stable while collectively providing the thermal control function, significantly improving mechanical robustness and ease of mounting.
Solution Approach 2:
The invention transitions from a three-dimensional bent tubing structure to a two-dimensional planar structure with embedded microchannels. The serpentine microchannel traces are embedded within flat planar layers, changing the spatial dimensionality from volumetric to planar, which enhances mechanical strength while maintaining thermal functionality.
2Ease of manufacture
If larger diameter tubing is used, then ease of manufacture is improved, but thermal conductivity deteriorates
Solution Approach 1:
The invention changes the critical parameter from tubing diameter to microchannel trace dimensions within planar layers. By using small-dimensional microchannels (rather than large diameter tubes), the device achieves superior thermal conductivity while remaining manufacturable through standard PCB or thin-film fabrication processes, resolving the contradiction between size and thermal performance.
Solution Approach 2:
The microchannel traces are locally optimized within specific regions of the planar layers, with serpentine patterns concentrated in thermal management zones. This local quality enhancement allows high thermal conductivity where needed while maintaining overall manufacturing simplicity through standard planar fabrication techniques.
3Strength
If fewer bends/turns are used in the pipe structure, then mechanical strength is improved, but thermal control efficiency deteriorates
Solution Approach 1:
The thermal control function is segmented across multiple planar layers with embedded microchannels, replacing the need for numerous macroscopic bends and turns. Each layer contains serpentine trace patterns that provide efficient thermal pathways without requiring structural bends, thus maintaining both strength and thermal efficiency.
Solution Approach 2:
The invention resolves the bend- efficiency contradiction by transitioning to a planar dimension where serpentine traces can achieve high thermal control efficiency through two-dimensional winding patterns without any three-dimensional bends or turns. The microchannel traces wind within the plane of each layer, eliminating structural weaknesses while maintaining thermal performance.
4Reliability
If micro-fabrication technology is used, then thermal conductivity is improved, but device complexity increases
Solution Approach 1:
The invention uses standard planar fabrication technologies (PCB manufacturing, thin-film deposition, or laminated composite techniques) that are already widely used in other industries. By making the microchannel embedded pulsating heat pipe compatible with these existing universal manufacturing processes, the device achieves high thermal conductivity without proportionally increasing fabrication complexity.
Solution Approach 2:
The invention merges the thermal control function with standard planar manufacturing processes. The serpentine microchannels are integrated directly into the planar layers during normal fabrication, combining structural support and thermal management functions in a single manufacturing step, thereby avoiding the need for separate complex assembly processes.
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 approach enhances thermal conductivity by 3 to 12 times that of conventional materials like aluminum, enabling effective thermal management in compact and lightweight designs suitable for aerospace and microelectronics, with improved mechanical robustness and manufacturing feasibility.
Implementation Method 1
Pulsating heat pipes are passive thermal control devices, employing a heat source evaporation section and a heat sink condensation section of the pipe to effect a two-phase heat pipe
Implementation Method 2
Heat is applied to the evaporation area causing a working fluid to change phase from a liquid to a vapor
Implementation Method 3
The vapor bubbles then travel to the condensation area where the vapor changes phase back into a liquid
Implementation Method 4
cooling is provided by conductance of thermal energy away from warm sources into radiators or heat exchangers and then dispersed
Implementation Method 5
At bends 2, heat is transferred (e.g., by radiation or convection) allowing this part of the device to act as a heat sink
Implementation Method 6
heat is transferred (e.g., by radiation or convection)
Data Source
AI summary
A heat pipe device and a corresponding method in which micro-channel embedded pulsating heat pipes are incorporated into a substrate. A volume of fluid in a vacuum is introduced into a micro-channel which will become slugs of liquid. Heating of the contents of the micro-channel at an evaporator region (heat source) will cause vaporization within the micro-channel and cooling at a heat sink will cause condensation within the micro-channel, acting to both drive fluid flow within the micro-channel and efficiently transfer heat. Such devices could be used in a number of different configurations, including one as a stacked set of micro-channel embedded substrates.