Vapor Chamber Bubble Pump for Dry-Out Prevention
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Solution Overview
Problem
Vapor chambers used for cooling power electronics modules face dry-out issues due to insufficient capillary force, leading to high wall temperatures and reduced component lifetime, as the evaporation flow length exceeds the capillary force's capability.
Innovation Solution
Incorporation of a bubble pump channel within the vapor chamber, which uses vapor bubbles to transport liquid cooling medium from a lower inlet to an upper outlet, preventing dry-out by ensuring adequate liquid supply to regions prone to liquid deficiency and hot spots, enhancing cooling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the evaporation flow length is increased to cool larger heat sources, then the cooling coverage is improved, but the capillary force becomes insufficient leading to dry-out phenomenon
Solution Approach 1:
The patent introduces a bubble pump as an intermediary mechanism between the heat source and cooling medium reservoir. This bubble pump uses vapor bubbles generated at the evaporation interface to actively transport liquid cooling medium through channels, mediating the liquid supply process and overcoming the limitation of passive capillary forces in long flow paths.
Solution Approach 2:
The patent replaces the traditional passive capillary force mechanism with an active vapor-driven pumping system. Instead of relying solely on capillary action which fails at long flow lengths, the system uses phase change (liquid to vapor) and bubble dynamics to create an active transport mechanism that can sustain liquid supply over extended distances.
2Force
If capillary channels are made smaller to enhance capillary force, then liquid transport capability is improved, but the bubble pumping effect is reduced
Solution Approach 1:
The patent applies different channel dimensions in different regions of the vapor chamber. Channels near the heat source have smaller dimensions to maximize capillary force and bubble generation, while channels further away or in liquid transport paths have larger dimensions to facilitate efficient liquid flow and bubble pumping. This spatial variation in channel geometry optimizes both capillary action and bubble pump performance.
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 bubble pump channel effectively increases the cooling performance of the vapor chamber by ensuring consistent liquid distribution, reducing the risk of dry-out and maintaining lower temperatures, thereby extending the lifespan of electronic components.
Implementation Method 1
the baseplate is adapted for transferring heat from the attachment side to the cavity, such that cooling medium evaporates at the evaporator side and condenses at the condenser wall
Implementation Method 2
the baseplate is adapted for transferring heat from the attachment side to the cavity, such that cooling medium evaporates at the evaporator side and condenses at the condenser wall
Implementation Method 3
Inside the channel due to heating, vapor bubbles form, which expand and press liquid cooling medium in the channel towards the outlet. The bubbles also may lift the liquid cooling medium, since they have a lower density than the liquid cooling medium.
Data Source
AI summary
A vapor chamber for cooling a heat source is provided. The vapor chamber includes a cavity between a baseplate and a condenser wall, the cavity containing a cooling medium, wherein the baseplate has an evaporator side towards the cavity and an attachment side opposite to the evaporator side for attaching the heat source, wherein the baseplate is adapted for transferring heat from the attachment side to the cavity, such that cooling medium evaporates at the evaporator side and condenses at the condenser wall, and wherein the vapor chamber further includes a channel, which is at least partially connected to the baseplate, with an inlet below a liquid level of the cooling medium and an outlet above the liquid level and which provides a bubble pump for transporting the liquid medium from the inlet to the outlet.