Heat Pipe Capillary Structure with Variable Wall Thickness
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Solution Overview
Problem
In heat pipes where the condensation section is placed lower than the evaporation section, the capillary action works against gravity, leading to ineffective fluid return and dry heating at the evaporation section, compromising heat transfer efficiency.
Innovation Solution
A heat pipe design with a capillary structure featuring a cold section with a thicker wall thickness at the condensation section and a heat section with a thinner wall thickness at the evaporation section, ensuring sufficient capillary action force and heat transfer even when working against gravity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the condensation section is placed lower than the evaporation section to utilize gravity for fluid flow, then the evaporation section can be effectively cooled, but the capillary structure cannot effectively return the condensed working fluid back to the evaporation section due to gravity working against capillary action
Solution Approach 1:
The capillary structure is designed with non-uniform porosity distribution, where the porosity varies along the length of the capillary structure. Specifically, the porosity is higher in the region closer to the condensation section and lower near the evaporation section, creating locally optimized capillary forces that can overcome gravity and reliably return the condensed working fluid to the evaporation section while maintaining effective cooling at the evaporation section
2Reliability
If the capillary structure has high porosity to enhance fluid return capability against gravity, then the fluid can be returned to the evaporation section, but the evaporation rate decreases due to reduced capillary action force
Solution Approach 1:
The capillary structure employs spatially varying porosity, with higher porosity in the condensation-side region to facilitate fluid return against gravity, and lower porosity in the evaporation-side region to maintain strong capillary action force for high evaporation rate. This local differentiation resolves the contradiction between fluid return capability and evaporation productivity
Solution Approach 2:
The capillary structure is conceptually segmented into different functional zones along its length, with each zone having optimized porosity characteristics for its specific function: the condensation-side zone prioritizes fluid return, while the evaporation-side zone prioritizes evaporation rate, achieving both objectives simultaneously through segmented design
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 maintains a strong capillary action force and evaporation rate, enabling effective cooling circulation and heat transfer, ensuring the heat pipe functions properly despite gravitational orientation.
Implementation Method 1
the heat pipe employs a capillary structure to promote the flow of the condensed working fluid back to the evaporation section
Implementation Method 2
partial evaporation of the working fluid takes place at the evaporation section so as to produce high pressure to drive the gaseous working fluid to flow towards the condensation section
Implementation Method 3
the gaseous working fluid is cooled and condensed into liquid at the condensation section
Data Source
AI summary
This disclosure relates to a heat pipe includes a tubular body and a capillary structure. The tubular body has an inner surface. The inner surface forms a sealed chamber. The capillary structure is located in the sealed chamber and arranged on the inner surface. The tubular body includes a condensation section and an evaporation section connected to each other. The capillary structure includes a cold section and a heat section connected to each other. The cold section is disposed on the condensation section, and the heat section is disposed on the evaporation section. A wall thickness of the cold section is greater than a wall thickness of the heat section.