Dual-Layer Sintered Heat Pipe Wick for Turbulence Suppression
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Solution Overview
Problem
The heat pipe disclosed in Patent Document 1 experiences turbulence in the circulation flow of the working fluid due to droplet formation near the boundary between the intermediate and evaporating portions, leading to increased thermal resistance and reduced heat transfer characteristics.
Innovation Solution
A heat pipe configuration featuring a first sintered body layer of copper powder and a second sintered body layer with larger copper powder particles, where the second layer extends to the intermediate portion, isolating vapor flow from liquid flow and providing separate paths through grooves and internal cavities to prevent turbulence, with the first layer being closer to the central position and filled in grooves to enhance evaporation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wick structure made of sintered metal fiber is provided in the intermediate portion to promote reflux of liquid-phase working fluid, then capillary force is increased and heat transfer is improved, but droplets form near the boundary between intermediate and evaporating portions causing turbulence and increased thermal resistance
Solution Approach 1:
The wick structure is divided into two distinct layers: a first sintered body layer made of fine copper powder (average particle size 50-150 μm) in the evaporating portion, and a second sintered body layer made of coarse copper powder (average particle size 150-300 μm) in the intermediate portion. This segmentation allows each layer to perform its specific function - the fine first layer prevents droplet formation at the boundary, while the coarse second layer provides strong capillary force for reflux, thereby eliminating turbulence while maintaining heat transfer efficiency.
2Productivity
If the first sintered body layer is positioned closer to the central position of the internal space, then evaporation efficiency is enhanced, but the structure becomes more complex
Solution Approach 1:
The wick structure employs local quality differentiation by using two layers with distinct particle sizes and positions. The first layer of fine copper powder is positioned closer to the central axis in the evaporating portion to optimize evaporation efficiency, while the second layer of coarse copper powder is positioned in the intermediate portion to maximize capillary reflux. This local optimization of each layer's properties and position achieves high evaporation efficiency without requiring overly complex structural arrangements.
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 reduces thermal resistance and enhances heat transfer characteristics by preventing turbulence and ensuring efficient evaporation of the liquid-phase working fluid, resulting in a heat pipe with improved heat transfer efficiency.
Implementation Method 1
a wick structure (hereinafter, sometimes referred to as a 'wick structure (metal powder)') made of a sintered body of particulate metal powder is provided in an evaporating portion
Implementation Method 2
an evaporating portion that is provided on one end side and evaporates a liquid-phase working fluid to change a phase into a gas-phase working fluid
Implementation Method 3
a condensing portion that is provided on the other end side and condenses the gas-phase working fluid to change a phase into a liquid-phase working fluid
Implementation Method 4
heat is transferred between the evaporating portion and the condensing portion in the tubular vessel
Data Source
AI summary
A heat pipe includes a container having an internal space for a working fluid, and an evaporating portion that evaporates a liquid-phase working fluid to change it into a gas-phase working fluid. A condensing portion separated from the evaporating portion condenses a gas-phase working fluid to change it into a liquid-phase working fluid, and an intermediate portion located between the evaporating portion condensing portion. The heat pipe includes a first sintered body layer on an inner peripheral surface of the evaporating portion and includes a product of sintering a first copper powder. A second sintered body layer continuously extends to at least a part of an inner peripheral surface of the intermediate portion and stacked on an inner peripheral surface of the first sintered body layer and includes a product of sintering of a second copper powder having a larger average particle size than the first copper powder.