Loop Heat Pipe Evaporator Three-Layer Capillary Core
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Solution Overview
Problem
The existing double-layer capillary core structures in loop heat pipes face challenges in integrating different sintering temperatures and bonding interfaces, leading to issues with air bubble formation and sealing, which affect heat transfer performance and operation stability.
Innovation Solution
A three-layer composite capillary core structure is introduced, comprising an evaporation core, a heat insulation core, and a transmission core, where the evaporation and transmission cores are made of materials with higher heat conducting coefficients and lower melting points, and the heat insulation core is made of materials with higher melting points and lower heat conducting coefficients, all sintered together to form a tightly sealed and high-permeability structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the capillary core uses materials with high heat conducting coefficient to improve evaporation performance, then heat transfer performance is improved, but heat leakage from evaporator to liquid storage device increases
Solution Approach 1:
The capillary core is divided into two distinct layers: an evaporation layer with high heat conducting coefficient materials (copper, aluminum, nickel) to improve heat transfer performance, and a liquid storage layer with low heat conducting coefficient materials to reduce heat leakage. This segmentation allows each layer to optimize its thermal properties independently for its specific function.
Solution Approach 2:
Different regions of the capillary core are assigned different material properties tailored to local requirements. The evaporation layer uses high thermal conductivity materials where heat transfer is critical, while the liquid storage layer uses low thermal conductivity materials where heat insulation is needed, achieving local optimization of thermal characteristics.
2Power
If the capillary core uses small pore diameter to increase capillary driving force, then ultimate heat transfer capability is improved, but permeability and liquid flow resistance worsen
Solution Approach 1:
The capillary core structure is segmented into two layers with different pore characteristics. The evaporation layer has smaller pore diameters to generate strong capillary driving force for high heat transfer capability, while the liquid storage layer has larger pore diameters to ensure high permeability and low flow resistance for adequate liquid supply.
Solution Approach 2:
The capillary core employs a composite structure combining two layers with different pore size distributions. The evaporation layer uses fine-pored materials for high capillary pressure, while the liquid storage layer uses coarse-pored materials for high permeability, creating a composite system that balances capillary force and flow resistance.
3Power
If double-layer capillary cores with different sintering temperatures are used to achieve different heat conducting coefficients, then heat transfer performance is improved, but integration difficulty and sealing reliability worsen
Solution Approach 1:
The sintering parameters are optimized and differentiated for each layer to achieve the desired material properties. The evaporation layer is sintered at temperatures appropriate for high thermal conductivity materials, while the liquid storage layer is sintered at temperatures suitable for low thermal conductivity materials, allowing each layer to achieve its target microstructure and thermal properties without compromising integration.
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 effectively reduces heat leakage, improves heat transfer performance, and enhances the capillary driving force and permeability, thereby stabilizing the operation of the loop heat pipe while maintaining high heat transfer capabilities.
Implementation Method 1
a capillary pinhole on the evaporation surface forms a meniscus surface to provide a capillary driving force for driving a working medium to circulate
Implementation Method 2
the contact surface of the capillary core with a porous structure and the heat source is used as an evaporation surface
Implementation Method 3
the capillary core should have a relatively low heat conducting coefficient to reduce heat leaked from the evaporator to the liquid storage device
Implementation Method 4
a liquid is evaporated on the outer surface of a capillary core in the evaporator to absorb heat outside the evaporator
Implementation Method 5
the generated steam flows from the steam pipeline to the condenser and releases heat in the condenser to a heat sink so as to be condensed
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a preparation method of a loop heat pipe evaporator and belongs to the technical field of heat control. The method is a hot-press sintering method comprising the steps: putting a shell of the evaporator into a mould, uniformly and compactly filling corresponding positions in the mould with material powders of an evaporation core, a heat insulation core and a transmission core, applying a pressure high enough to tightly fit the evaporation core and the transmission core to the shell at corresponding sintering temperatures of powder materials for the evaporation core and the transmission core, carrying out hot-press sintering for molding, carrying out cooling after metallurgically bonding the powder materials of the evaporation core and the transmission core, and carrying out demolding to obtain the loop heat pipe evaporator, wherein the mould is provided with corresponding structures shaped like steam channels on positions where the evaporation core is provided with the steam channels. By using the evaporator prepared by using the method, heat leaked towards a liquid storage device can be effectively reduced, the permeability is increased while the capillary force is increased, and the problem that it is difficult to improve the heat transfer performance, the starting performance and the operation stability while increasing the heat conducting coefficient and permeability of a capillary core of a loop heat pipe is solved.