Hybrid Two-Phase Cooling Device With Non-Permeable Barrier
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Solution Overview
Problem
Current cooling technologies face limitations in efficiently removing high heat fluxes from electronic devices, particularly gallium nitride high-electron mobility transistors, due to issues such as mechanical stress, limited heat flux capability, high pumping power, and flow instabilities, which lead to thermal management challenges and device reliability concerns.
Innovation Solution
A hybrid two-phase cooling system utilizing a compact heat transfer device with a wick structure that enables evaporation-based heat removal, employing a mechanically pumped two-phase loop with a non-permeable barrier to separate vapor and liquid phases, and using aluminum nitride substrates for thermal expansion matching, allowing for efficient heat transfer over long distances with low thermal resistance and low pumping power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If diamond heat sink is used, then thermal conductivity is improved, but mechanical stress between diamond and GaN increases
Solution Approach 1:
The patent introduces an intermediate layer between the diamond heat sink and GaN device. This intermediary layer acts as a buffer to reduce mechanical stress caused by thermal expansion coefficient mismatch while maintaining the high thermal conductivity benefit of diamond.
Solution Approach 2:
The patent employs composite material structures combining diamond with other materials that have compatible thermal expansion properties. This composite approach allows achieving high thermal conductivity while reducing mechanical stress through material composition optimization.
2Temperature
If vapor chamber is used, then heat spreading capability is improved, but ability to handle alternating heat sources and heat sinks is worsened
Solution Approach 1:
The patent divides the cooling system into separate vaporization chambers and condensation chambers that can be independently configured. This segmentation allows the system to adapt to alternating heat sources by directing vapor flow dynamically between different chamber pairs.
Solution Approach 2:
The patent incorporates dynamic flow control mechanisms that allow the vapor chamber system to adapt its operation mode. The system can switch between different heat source configurations by controlling vapor flow paths, enabling versatility for alternating heat sources while maintaining effective heat spreading.
3Temperature
If microchannel liquid cooling is used, then heat removal capability is improved, but pumping power requirement increases
Solution Approach 1:
The patent utilizes two-phase (liquid-vapor) heat transfer in microchannels instead of single-phase liquid cooling. The phase transition process provides much higher heat removal capability per unit mass flow rate, dramatically reducing the required pumping power while maintaining effective cooling.
Solution Approach 2:
The patent changes the thermal transfer parameter from sensible heat (single-phase) to latent heat (two-phase). This parameter change enables significantly higher heat flux removal with minimal flow rates, thereby reducing pumping power requirements.
4Temperature
If microchannel two-phase cooling is used, then heat removal efficiency is improved, but flow stability deteriorates due to dry-out and hot spots
Solution Approach 1:
The patent introduces a wick structure as an intermediary element in the microchannel two-phase system. The wick ensures stable liquid supply to the evaporation zone through capillary action, preventing dry-out conditions and maintaining flow stability while preserving high heat removal efficiency.
Solution Approach 2:
The patent employs passive capillary wick structures that automatically supply liquid to the evaporation zones without requiring external pumping within the microchannel array. This self-service mechanism maintains stable two-phase flow and prevents hot spots through uniform liquid distribution.
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 effectively transports large amounts of heat with low thermal resistance, maintains isothermal conditions, and operates at different gravity orientations, enhancing the reliability and power density of electronic devices by preventing hotspots and reducing mechanical stress, while minimizing pumping power.
Implementation Method 1
The heat removal process relies on evaporation from a wick in contact with the heat source(s). Evaporation allows the working fluid, through phase change, to carry away latent heat from the heat source in the form of vapor.
Implementation Method 2
Evaporation allows the working fluid, through phase change, to carry away latent heat from the heat source in the form of vapor.
Implementation Method 3
Throughout the cooling process, vapor and liquid are separated from each other by a non-permeable barrier.
Implementation Method 4
The liquid or liquid working fluid is transported laterally through the wick structure, rather than flowing along the entire wick.
Data Source
AI summary
A heat transfer device includes a hollow spacer between opposed substrates, defining an enclosure, at least one of the substrates adapted to be secured to at least one heat source. A non-permeable barrier is in the enclosure between the substrates. A first chamber inside the enclosure is defined by the spacer, the substrates, and the barrier, the first chamber in fluid communication with at least one first inlet and first outlet. A second chamber inside the enclosure and outside the first chamber and is defined by the spacer, the substrates, and the barrier, the second chamber in fluid communication with at least one second outlet. A wick structure is secured to at least one substrate, a first portion of the wick structure in the first chamber, and a second portion of the wick structure in the second chamber and interconnecting in passive liquid communication with the first portion.