Evaporator assemblies, vapor chambers, and methods for fabricating vapor chambers
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Solution Overview
Problem
Vapor chambers face limitations in heat flux removal due to the phenomenon of dry out, where the evaporator surface 'dries out' as the power generating device raises temperature, causing heat generating devices to exceed their maximum operating temperature, especially with wide band gap devices that dissipate high heat fluxes.
Innovation Solution
The introduction of an array of porous posts connecting the evaporator and condenser surfaces, along with an array of vapor vents within the evaporator surface, provides a wicking path for condensed liquid to return and additional nucleation sites for efficient evaporation, minimizing dry out risks and enhancing heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power generating device raises temperature to increase heat flux removal, then heat dissipation capability is improved, but the evaporator surface dries out causing the device to exceed maximum operating temperature
Solution Approach 1:
The patent applies porous materials in the form of a porous layer coating the evaporator surface and porous posts extending from the evaporator surface. These porous structures provide capillary action to continuously supply liquid to the evaporator surface, preventing dry out while enabling high heat flux removal. The porous layer and posts create a reservoir effect that maintains liquid supply even at elevated temperatures and high power densities.
Solution Approach 2:
The patent segments the evaporator surface by incorporating an array of posts that divide the evaporator surface into multiple regions. This segmentation increases the surface area for evaporation and creates multiple liquid supply paths, ensuring that liquid can reach all areas of the evaporator surface efficiently. The posts act as individual wicking channels that prevent localized dry out.
2Power
If the evaporator surface area is increased to improve heat dissipation, then heat flux removal is enhanced, but the device size increases
Solution Approach 1:
The patent transitions from a two-dimensional evaporator surface to a three-dimensional structure by adding posts that extend vertically from the evaporator surface. This dimensional change increases the effective heat transfer surface area without proportionally increasing the footprint area. The posts provide additional evaporation surface area while maintaining a compact device footprint.
Solution Approach 2:
The patent applies local quality by creating regions of different properties on the evaporator surface. The posts create localized regions with enhanced liquid supply and evaporation capability, concentrating heat transfer functionality in specific areas. This allows high heat flux removal in targeted regions without requiring uniform expansion of the entire evaporator surface area.
3Power
If an array of posts and vapor vents is added to prevent dry out and enhance evaporation, then heat dissipation performance is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into integrated structures. The posts serve dual purposes: they act as structural support elements and simultaneously function as wicking channels for liquid supply. The vapor vents are integrated directly into the evaporator surface, eliminating the need for separate vapor removal components. This merging reduces overall device complexity while maintaining enhanced heat dissipation performance.
Solution Approach 2:
The posts perform multiple functions: they provide structural support, serve as liquid wicking channels through their porous structure, act as nucleation sites for vapor formation, and create flow channels for vapor removal. This multi-functionality reduces the number of separate components needed, simplifying the overall device architecture while achieving superior heat dissipation.
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 significantly raises the dry out temperature, allowing heat generating devices to operate at elevated temperatures with minimized dry out risks, achieving the highest heat flux dissipation of 589 W/cm2 and lowest total thermal resistance of 0.28 K/W among evaluated designs.
Implementation Method 1
an array of posts extending from the evaporator surface... a porous layer disposed on the evaporator surface, the array of posts
Implementation Method 2
an array of vapor vents within the evaporator surface... provides additional nucleation sites for efficient evaporation
Implementation Method 3
Vapor chambers having low thermal resistance and high heat dissipation... achieving the highest heat flux dissipation
Implementation Method 4
a condenser plate... the condenser surface is bonded to a top surface of the array of posts such that the evaporator assembly and the condenser plate define a vapor chamber
Data Source
AI summary
Evaporator assemblies, vapor chamber assemblies, and methods for fabricating a vapor chamber are disclosed. In one embodiment, an evaporator assembly for a vapor chamber includes an evaporator surface, an array of posts extending from the evaporator surface, and an array of vapor vents within the evaporator surface. Each vapor vent of the array of vapor vents is configured as a depression within the evaporator surface. The evaporator assembly further includes a porous layer disposed on the evaporator surface, the array of posts, and the array of vapor vents.