Wettability-Patterned Vapor Chambers Without Wick Pressure Loss
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Solution Overview
Problem
Conventional vapor chambers face limitations in heat flux due to high viscous losses and pressure drops caused by wicks, leading to thermal runaway, which restricts the maximum heat flux they can handle effectively.
Innovation Solution
A wick-free vapor chamber design utilizing wettability-patterned condensers and evaporators, where patterned domains control vapor condensation and transport condensate efficiently without the need for wicks, reducing viscous losses and enhancing heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wicks are used to transport condensate in vapor chambers, then condensate transport is achieved, but viscous losses and pressure drops increase leading to thermal runaway
Solution Approach 1:
The patent removes the wick component entirely from the vapor chamber system. Instead of using wicks to transport condensate, the invention employs wettability-patterned surfaces that utilize capillary forces and gravity to return condensate to the evaporator region, thereby eliminating the source of high viscous losses and pressure drops while preventing thermal runaway
Solution Approach 2:
The patent modifies the surface wettability parameters of the vapor chamber walls through patterned hydrophilic/hydrophobic regions. This creates controlled capillary pressure gradients that drive condensate return without requiring wicks, thus reducing viscous losses while maintaining reliable condensate transport and preventing thermal runaway
2Speed
If wicks with small pore size are used to achieve rapid condensate transport, then transport speed increases, but pressure drops increase degrading performance
Solution Approach 1:
The patent eliminates the wick structure entirely, replacing it with wettability-patterned surfaces that guide condensate flow through macroscopic patterned regions rather than microscopic pores. This maintains rapid condensate transport speed while avoiding the high pressure drops associated with small pore sizes
Solution Approach 2:
The patent transitions from one-dimensional flow through porous wick media to two-dimensional flow along patterned surface regions. The wettability patterns create defined flow paths on the surface plane, enabling rapid condensate transport without the constriction and pressure losses of small pore sizes
3Power
If wick dimensions are increased to handle higher heat flux, then maximum heat flux capacity increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent removes the complex wick structure entirely and replaces it with relatively simple wettability-patterned surfaces. These surfaces can be fabricated through conventional techniques such as screen printing, spray coating, or lithography, significantly reducing manufacturing complexity while maintaining or enhancing maximum heat flux capacity
Solution Approach 2:
The patent changes the approach to handling higher heat flux by modifying surface wettability parameters rather than increasing wick dimensions. The patterned hydrophilic/hydrophobic regions create effective capillary pressure gradients that scale with heat flux requirements, avoiding the manufacturing complexity of larger or more complex wick structures
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 wick-free design achieves lower thermal resistances and increased efficiency in heat transfer, allowing for higher heat flux handling and preventing thermal runaway, thus improving thermal management in electronics and other applications.
Implementation Method 1
The vapor created in this manner condenses on the cooled side of the device and the condensate travels back to the evaporator through capillary action to restart the phase-change cycle.
Implementation Method 2
The wettability-patterned evaporator is configured to: i) accept condensate from the wettability-patterned condenser and ii) transport the condensate along patterned domains formed on the wettability-patterned evaporator to a hot domain portion
Implementation Method 3
Vapor chambers are hermetically sealed, hollow devices that carry a phase-changing liquid to attain a high effective thermal conductivity (low thermal resistance) produced by the spreading of vapor generated via thin-film evaporation or even boiling of the liquid in contact with the hot side of the device
Data Source
AI summary
Wick-free vapor chambers and hybrid vapor chambers are described. An example wick-free vapor chamber includes a wettability-patterned condenser configured to control vapor condensation along patterned domains formed on the wettability-patterned condenser; and a wettability-patterned evaporator. The wettability patterned evaporator is configured to: i) accept condensate from the wettability-patterned condenser and ii) transport the condensate along patterned domains formed on the wettability-patterned evaporator to one or more hot domain portions of the wettability-patterned evaporator. An example hybrid vapor chamber includes a wettability patterned condenser configured to control vapor condensation along patterned domains formed on the wettability-patterned condenser; and an evaporator configured to accept condensate from the wettability -patterned condenser.