Variable-Thickness Wick Structure for Heat Pipe Reflux and Heat Transfer
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Solution Overview
Problem
Existing heat pipes with uniform wick thickness in cross-sections face challenges in balancing flow resistance and thermal resistance, leading to inefficiencies in heat transport.
Innovation Solution
A heat pipe design with varying wick thickness and shape in different sections, featuring thin and thick wall portions in the evaporation and condensation portions, and a uniform thickness in the intermediate portion, to optimize fluid flow and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the wick is made constant in cross-section, then the flow resistance of the working fluid in the wick becomes uniform in the circumferential direction, but the thermal resistance due to the thickness of the wick increases
Solution Approach 1:
The wick thickness is made non-uniform in the circumferential direction, with a thin wall portion and a thick wall portion. The thin wall portion reduces thermal resistance for better heat conduction, while the thick wall portion reduces flow resistance for improved working fluid reflux. This local variation in thickness allows each region to optimize for its specific function.
Solution Approach 2:
The wick cross-section is divided into functionally distinct regions: a thin wall portion and a thick wall portion. This segmentation allows different parts of the wick to perform different functions - the thin portion for thermal conduction and the thick portion for fluid flow - thereby resolving the contradiction between thermal resistance and flow resistance.
2Reliability
If the thickness of the wick is increased, then the flow resistance of the working fluid decreases, but the thermal resistance of the wick increases
Solution Approach 1:
Instead of uniformly increasing wick thickness, the invention applies local quality variation by creating a thick wall portion for fluid flow and a thin wall portion for heat conduction. This allows the system to achieve low flow resistance without suffering from uniformly high thermal resistance.
Solution Approach 2:
The wick is segmented into thick and thin wall portions with distinct functions. The thick wall portion accommodates working fluid flow with reduced resistance, while the thin wall portion provides a thermal conduction path, thereby decoupling the conflicting requirements of flow resistance and thermal resistance.
3Temperature
If the thickness of the wick is decreased, then the thermal resistance of the wick decreases, but the flow resistance of the working fluid in the wick increases
Solution Approach 1:
The wick employs local quality differentiation where the thin wall portion optimizes for thermal conduction (low thermal resistance) and the thick wall portion optimizes for fluid flow (low flow resistance). This localized optimization resolves the contradiction by allowing each region to be thin where heat conduction is needed and thick where fluid flow is needed.
Solution Approach 2:
The wick cross-section is segmented into functional zones: a thin wall portion for thermal management and a thick wall portion for fluid transport. This segmentation enables the system to achieve both low thermal resistance and low flow resistance simultaneously by assigning different thickness characteristics to different functional regions.
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 reduces both flow resistance and thermal resistance, enhancing the reflux performance and distance of heat transport, thereby improving heat transfer efficiency.
Implementation Method 1
an evaporation portion, a condensation portion, and an intermediate portion provided between the evaporation portion and the condensation portion are provided at different positions in a longitudinal direction of the container
Implementation Method 2
an evaporation portion, a condensation portion, and an intermediate portion provided between the evaporation portion and the condensation portion are provided at different positions in a longitudinal direction of the container
Implementation Method 3
a wick accommodated in the container... the wick has an annular shape and includes a thin wall portion and a thick wall portion... since the thermal resistance in the thin wall portion of the wick is small and the flow resistance in the thick wall portion of the wick is small, reflux performance of the working fluid can be improved
Data Source
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AI summary
A heat pipe includes a container in which a working fluid is sealed; and a wick accommodated in the container, in which an evaporation portion, a condensation portion, and an intermediate portion provided between the evaporation portion and the condensation portion are provided at different positions in a longitudinal direction of the container, in a transverse cross section orthogonal to the longitudinal direction, a shape of the wick in the intermediate portion is different from a shape of the wick in the evaporation portion and the condensation portion, and in the evaporation portion and the condensation portion, the wick has an annular shape and includes a thin wall portion and a thick wall portion having a thickness larger than a thickness of the thin wall portion.