Heat Pipe Capillary Structure Porosity Gradient
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Solution Overview
Problem
Conventional thin heat pipes face challenges in achieving high heat flux and portability due to insufficient capillary reflow and vaporization space, leading to poor thermal conductivity and manufacturing difficulties, especially when trying to separate liquid and vapor effectively.
Innovation Solution
A heat pipe design with a capillary structure featuring portions of higher and lower porosity to isolate liquid and vapor, divided into evaporation, insulation, and condensation sections, where the liquid delivery structure forms vapor channels with a center portion of higher porosity and an outer layer of lower porosity, enhancing heat conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the heat pipe is pressed flatly to reduce thickness below 2 mm, then portability is improved, but thermal conductivity becomes very poor
Solution Approach 1:
The capillary structure is designed with different porosity regions: a first capillary structure with higher porosity (40-60%) in the vapor region and a second capillary structure with lower porosity (20-40%) in the liquid channel region. This local differentiation allows the thin heat pipe to maintain proper liquid-vapor separation and capillary reflow capability, preserving thermal conductivity while achieving reduced thickness for portability.
2Length of moving object
If capillary structures are distributed partially on the internal cavity wall to improve liquid and vapor space, then portability is improved, but capillary reflow capability is reduced significantly
Solution Approach 1:
The capillary structure is designed with different porosity regions: a first capillary structure with higher porosity (40-60%) in the vapor region and a second capillary structure with lower porosity (20-40%) in the liquid channel region. This local differentiation allows the thin heat pipe to maintain proper liquid-vapor separation and capillary reflow capability, preserving thermal conductivity while achieving reduced thickness for portability.
3Reliability
If sintered metal powder is used as a secondary liquid channel to separate liquid and gas, then liquid-vapor separation is achieved, but capillary reflow capability is offset and performance is affected
Solution Approach 1:
The capillary structure is designed with different porosity regions: a first capillary structure with higher porosity (40-60%) in the vapor region and a second capillary structure with lower porosity (20-40%) in the liquid channel region. This local differentiation allows the thin heat pipe to maintain proper liquid-vapor separation and capillary reflow capability, preserving thermal conductivity while achieving reduced thickness for portability.
4Ease of manufacture
If a circular core rod is adopted for simple manufacturing, then ease of manufacture is improved, but liquid and vapor separation is insufficient
Solution Approach 1:
The capillary structure is designed with different porosity regions: a first capillary structure with higher porosity (40-60%) in the vapor region and a second capillary structure with lower porosity (20-40%) in the liquid channel region. This local differentiation allows the thin heat pipe to maintain proper liquid-vapor separation and capillary reflow capability, preserving thermal conductivity while achieving reduced thickness for portability.
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 design effectively separates vapor and liquid channels, improving heat conductivity and overcoming manufacturing and portability limitations of thin heat pipes, while allowing for efficient heat transfer and easy manufacturing.
Implementation Method 1
a heat pipe with a capillary structure, wherein the whole or a part of the capillary structure has a portion of a higher porosity and a portion of a lower porosity
Implementation Method 2
the capillary structure is usually distributed on the whole or a part of an internal cavity wall of the heat pipe
Implementation Method 3
the vapor in the cavity of the heat pipe is still in direct contact with the liquid channel
Data Source
AI summary
A heat pipe is divided into an evaporation section, an insulation section and a condensation section. The insulation section includes a pipe section and a liquid delivery structure. The pipe section has a top wall and a bottom wall. The liquid delivery structure is a solid structure and in contact with the top and bottom walls of the pipe section. The liquid delivery structure and the top and bottom walls of the pipe section form a vapor channel. The liquid delivery structure is divided into a center portion and an outer layer, and the center portion has a porosity greater than the porosity of the outer layer. The outer layer is coupled to the center portion, and the center portion and the vapor channel are spaced from one another, so as to achieve the liquid and vapor isolation and improve the heat conducting effect of the heat pipe.