Loop Thermosyphon Evaporator Segmentation for High-Heat Flux Cooling
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Solution Overview
Problem
Conventional heat transfer technologies, such as heat pipes and thermosyphons, face limitations in effectively cooling high-power and high-power density devices due to increased thermal resistance, necessitating the development of more efficient heat transfer solutions.
Innovation Solution
A loop thermosyphon system that combines passive heat pipe principles with pumped liquid cooling, utilizing a working fluid to achieve ultra-low thermal resistance and efficiently transfer heat over long distances, even in confined spaces like a 1U server, by using a vapor and liquid conduit system with evaporators and condensers that include manifold structures and fin arrangements for enhanced heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat pipe or thermosyphon technology is used, then the system structure is simple and passive, but the thermal resistance increases and heat transfer efficiency decreases for high-power devices
Solution Approach 1:
The evaporator is segmented into multiple independent boiling channels (e.g., 4 channels) that are arranged in parallel, allowing heat to be distributed across multiple pathways. This segmentation reduces thermal resistance in each channel while maintaining the passive thermosyphon structure, enabling effective cooling of high-power devices without requiring complex active pumping systems
Solution Approach 2:
The patent transitions from traditional single-phase or simple two-phase heat transfer to enhanced two-phase heat transfer by introducing a vapor space above the boiling channels. This dimensional addition allows vapor to rise and condense on the condenser surfaces, creating an efficient heat rejection pathway that significantly reduces thermal resistance while keeping the overall system structure relatively simple
2Reliability
If the heat transfer surface area is increased to reduce thermal resistance, then heat transfer efficiency improves, but the device volume and complexity increase
Solution Approach 1:
The condenser utilizes thin fin structures that extend from the condenser body, providing large heat transfer surface area in a compact volume. These thin film-like fins allow efficient heat rejection from the vapor condensation process without significantly increasing the overall device volume, thus reducing thermal resistance while maintaining compact dimensions suitable for high-power density applications
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 loop thermosyphon system achieves low thermal resistance and high heat flux capabilities, enabling the passive cooling of up to 1 kW of heat from an enclosed enclosure with a thermal resistance of 0.01 °C-cm²/W and heat flux of up to 90 W/cm², effectively addressing the limitations of existing technologies.
Implementation Method 1
as a heat-transfer fluid in the liquid phase absorbs heat in an evaporator region, the liquid phase transitions to a vapor phase
Implementation Method 2
a heat-transfer fluid can change phase from liquid to gas (or vice-versa) to absorb (or to dissipate, respectively) relatively large amounts of energy
Implementation Method 3
The vapor phase flows to a condenser region where the vapor phase rejects heat and condenses, returning to the liquid phase
Implementation Method 4
a thermosyphon typically relies on gravity to return the condensed liquid phase to the evaporator
Implementation Method 5
a loop thermosyphon can transport heat over a long distance due to an ultra-low thermal resistance provided by two-phase heat transfer
Data Source
AI summary
A loop thermosyphon can combine the best of heat-pipes and traditional liquid-cooling systems that include a mechanical pump. A disclosed heat-transfer device includes a first heat-transfer component and a second heat-transfer component fluidly coupled with each other by a first conduit and a second conduit. A first manifold is positioned in the first heat-transfer component and defines a first plurality of liquid pathways. The first manifold fluidly couples with the first conduit. A second manifold is also positioned in the first heat-transfer component and defines a second plurality of liquid pathways fluidly coupled with and extending from the first plurality of liquid pathways. The second manifold further defines a plurality of boiling channels, a plurality of accumulator channels and a vapor manifold. The boiling channels extend transversely relative to and are fluidly coupled with the second plurality of liquid pathways. The plurality of accumulator channels extends transversely relative to and are fluidly coupled with the plurality of boiling channels. The vapor manifold is configured to collect vapor from one or more of the plurality of boiling channels, one or more of the plurality of accumulator channels, or both. The first heat-transfer component further defines an outlet fluidly coupling the vapor manifold with the second conduit. Electrical devices incorporating such a heat-transfer device also are disclosed, as well as associated methods.