Loop Thermosiphon Vapor-Liquid Path Design to Prevent Dry Out
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Solution Overview
Problem
Existing loop thermosiphons face challenges in enhancing thermal performance by preventing dry out and flooding, which limits heat transfer efficiency, particularly at high heat flux and varying filling ratios.
Innovation Solution
A loop thermosiphon assembly with a thermal interface component, vapor channels, and coolant pipes configured to direct vaporized coolant upwards and liquefied coolant downwards, incorporating features like porous linings, capillary wicking layers, and solid barriers to manage coolant flow and prevent backflow, thereby increasing heat transfer rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the filling ratio and coolant flow rate are raised to enhance efficiency, then heat transfer rate is improved, but dry out and flooding occur more easily
Solution Approach 1:
The patent segments the evaporator into multiple heat exchange chambers, each with independent capillary wicking structures. This segmentation allows localized coolant distribution and vapor escape paths, preventing both dry out (by ensuring adequate coolant supply to each chamber) and flooding (by providing multiple vapor escape routes). The segmented design enables the system to operate at higher filling ratios and flow rates without the harmful effects of uneven coolant distribution.
Solution Approach 2:
The patent employs porous materials including capillary wicking layers and porous linings in the heat exchange chambers and coolant pipes. These porous structures provide capillary forces that actively draw coolant to high-heat-flux regions, preventing dry out. Simultaneously, the porous linings in the downcomer prevent liquid coolant from escaping into the vapor channel, preventing flooding. This enables reliable operation at enhanced filling ratios and flow rates.
2Power
If high heat flux is applied to increase cooling capacity, then heat transfer efficiency is improved, but dry out occurs more easily
Solution Approach 1:
The patent changes the physical parameters of the heat exchange chambers by incorporating capillary wicking layers with specific pore size distributions and porous linings with controlled porosity. These parameter changes enable the structures to generate sufficient capillary pressure to supply coolant to high heat flux regions, preventing dry out even when high cooling capacity is required. The capillary parameters are optimized to match the heat flux conditions.
3Productivity
If large fill ratio is used to increase coolant inventory, then flooding occurs more easily, but heat transfer rate is improved
Solution Approach 1:
The patent extracts and separates the vapor transport function from the liquid coolant transport path by providing dedicated vapor channels and vapor barriers. The vapor barrier prevents liquid coolant from escaping into the vapor channel, while the vapor channel provides a clear path for vapor escape. This separation allows the use of larger fill ratios to increase coolant inventory and heat transfer rate without causing flooding, as the vapor escape paths remain unobstructed.
Solution Approach 2:
The porous lining in the downcomer acts as a selective barrier that allows vapor to pass through while blocking liquid coolant. This enables the system to tolerate larger fill ratios without flooding, as the porous structure prevents liquid from invading the vapor channel while maintaining adequate coolant inventory for high heat transfer rates.
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 assembly achieves higher heat transfer rates by preventing dry out and flooding, enhancing efficiency and handling high heat loads in electronic components such as processors.
Implementation Method 1
Heat is absorbed from a heat source by the evaporator causing liquid coolant within the evaporator to vaporize
Implementation Method 2
The condenser is where the vaporized liquid coolant releases heat, typically to a heat sink or other cooling mechanism(s). As the vapor cools in the condenser, it condenses back into a liquid state
Implementation Method 3
the system has self-sustaining motion driven by pressure differences between hot and cold regions and gravity
Implementation Method 4
the system has self-sustaining motion driven by pressure differences between hot and cold regions and gravity
Implementation Method 5
incorporating features like porous linings, capillary wicking layers, and solid barriers to manage coolant flow and prevent backflow
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A loop thermosiphon assembly may include a thermal interface component configured to be coupled to a heat source to be cooled, a channel coupled to the thermal interface component, a first vapor channel coupled to the channel, and one or more coolant pipes coupled to the first vapor channel and the channel. The channel includes a vapor barrier and a second vapor channel. The first vapor channel is in communication with the thermal interface component via the second vapor channel. The one or more coolant pipes is in communication with the thermal interface component via the vapor barrier. The second vapor channel and the first vapor channel direct vaporized liquid coolant upwards and away from the thermal interface component and heat source, and the one or more coolant pipes and the vapor barrier direct liquefied vapor coolant downwards and toward the thermal interface component and the heat source.