Flat Loop Heat Pipe Vapor Chamber for Wick Flow Resistance

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Solution Overview

Problem

The application of vapor chambers faces a conflict between improving product properties and the requirements for the capillary wick, where reducing capillary diameter enhances heat transfer capabilities but increases flowing resistance, and increasing capillary diameter improves permeability but may compromise heat transfer efficiency.

Innovation Solution

A vapor chamber based on a flat plate loop heat pipe is designed with a small-diameter capillary wick to provide high capillary force, and external loops without capillary wicks to minimize flowing resistance, thereby improving heat transfer capabilities and anti-overload and anti-gravity working capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the capillary diameter of the capillary wick is reduced, then the maximum heat transfer capability and ultimate heat flux are improved, but the flowing resistance increases

Engineering Contradiction:
Improvemaximum heat transfer capabilityVSAvoidflowing resistance
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The invention divides the capillary wick structure into two distinct parts: a small-diameter capillary wick in the evaporator for high capillary force and heat transfer capability, and a large-diameter capillary wick in the condenser for low flowing resistance. This segmentation allows each part to be optimized for its specific function, resolving the contradiction between heat transfer capability and flowing resistance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention applies different capillary wick diameters to different locations within the vapor chamber system. The evaporator region uses a small-diameter capillary wick to maximize heat transfer capability, while the condenser region uses a large-diameter capillary wick to minimize flowing resistance. This local differentiation of structure quality resolves the technical contradiction.

Inventive Principle:
Principle #3Local quality

2Loss of energy

If the capillary diameter of the capillary wick is increased, then the permeability and flowing resistance are reduced, but the maximum heat transfer capability and ultimate heat flux decrease

Engineering Contradiction:
Improveflowing resistanceVSAvoidultimate heat flux
Core Design Contradiction:
Loss of energyVSPower

Solution Approach 1:

The invention segments the capillary wick into two parts with different diameters: a large-diameter capillary wick in the condenser to reduce flowing resistance and improve permeability, and a small-diameter capillary wick in the evaporator to maintain high ultimate heat flux and heat transfer capability. This resolves the contradiction between permeability and heat transfer capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different capillary wick diameters are applied locally to different regions: large diameter in the condenser for low flowing resistance, and small diameter in the evaporator for high heat transfer capability. This local quality differentiation resolves the contradiction between permeability requirements and heat transfer requirements.

Inventive Principle:
Principle #3Local quality

3Power

If the size of the vapor chamber is increased, then the heat transfer capability is improved, but the installation space requirement increases

Engineering Contradiction:
Improveheat transfer capabilityVSAvoidinstallation space
Core Design Contradiction:
PowerVSArea of stationary object

Solution Approach 1:

The invention uses a thin-film flexible capillary wick structure that can be conformally deposited on the inner surface of the vapor chamber. This thin-film approach allows the vapor chamber to achieve high heat transfer capability through optimized capillary wick geometry while maintaining a compact, thin profile that minimizes installation space requirements.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention changes the geometric parameters of the capillary wick (diameter, porosity, thickness) to optimize heat transfer capability without increasing the overall vapor chamber size. By adjusting these parameters, high heat transfer performance is achieved within a compact form factor, resolving the contradiction between heat transfer capability and installation space.

Inventive Principle:
Principle #35Parameter changes

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 solution enhances the heat transfer capability, ultimate heat flux, and anti-overload and anti-gravity working capabilities of the vapor chamber, while allowing for increased size of the heat spreading plate and reduced thickness of the vapor chamber, effectively addressing the conflicting requirements for capillary wick diameter.

Implementation Method 1

reducing of the capillary diameter of the capillary wick can improve the maximum heat transfer capability, increase the ultimate heat flux, improve the anti-overload and anti-gravity working capability

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

temperature equalization is realized through a gas-liquid phase change of the working fluid

Methodology Applied
Scientific EffectPhase change: Phase Change

Implementation Method 3

liquid is evaporated on the outer surface of a capillary wick in the evaporator, and absorbs heat outside the evaporator

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 4

generated vapor flows from the vapor line to the condenser, and releases the heat in the condenser to a heat sink, so as to condense the vapor into liquid

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3614089B1Flat loop heat pipe-based vapor chamber
Publication Date: 2025.04.09 BEIJING INST OF SPACECRAFT SYST ENG
  • EP3614089B1 patent drawingFigure 1
  • EP3614089B1 patent drawingFigure 2
  • EP3614089B1 patent drawingFigure 3

AI summary

The present invention discloses a vapor chamber based on a flat plate loop heat pipe, so as to improve the heat transfer capability, the ultimate heat flux heat dissipation capability and the anti-overload and anti-gravity working capability of the vapor chamber, increase the size of a heat spreading plate, decrease the thickness of the vapor chamber, and solve a conflicting requirement of the improvement of the properties of the vapor chamber for a diameter size of a capillary wick. The flat plate loop heat pipe composed of an evaporator, a reservoir and a gas/liquid line is pre-buried in an aluminum alloy plate, so as to form the vapor chamber based on the flat plate loop heat pipe. The evaporator of the flat plate loop heat pipe is arranged in a region, attached to a biggest heat source of a chip to be subjected to heat dissipation, on the vapor chamber, and the side, provided with a vapor channel, of the evaporator is attached to the biggest heat source. "Heat sink attached regions" and "heat source attached regions" are arranged on the vapor chamber. The gas/liquid line led out from an outlet of the evaporator is cyclically disposed between the "heat sink attached regions" and the "heat source attached regions" on the vapor chamber. The gas/liquid line finally passes through the "heat sink attached regions" and then returns to the reservoir of the flat plate loop heat pipe.