Dual Chamber Loop Heat Pipe with Multi-Layer Wick
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Solution Overview
Problem
Conventional flat plate loop heat pipe structures suffer from heat leak and high local thermal resistance due to single-layer wick structures, which hinder effective heat dissipation and initialization, especially when high thermal conductivity materials are used, leading to inefficient thermal performance.
Innovation Solution
A loop heat pipe structure with a first wick layer providing sufficient capillary force and a second wick layer acting as a heat lock layer, combined with grooves on either the wick layer or the evaporator's bottom, to prevent heat from entering the reservoir and reduce pressure loss, thereby avoiding high vapor pressure and enhancing overall heat dissipation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single layer of wick structure with low thermal conductivity is used to prevent heat leak, then heat leak is reduced, but local thermal resistance in the evaporator increases
Solution Approach 1:
The evaporator is divided into multiple functional zones with different wick layer configurations. The first wick layer has low thermal conductivity to prevent heat leak, while the second wick layer has high thermal conductivity to reduce local thermal resistance. This segmentation allows each zone to optimize for its specific function without compromising the other.
Solution Approach 2:
Different regions of the evaporator are assigned different wick structures with tailored thermal properties. The first wick layer uses low thermal conductivity material in regions where heat leak prevention is critical, while the second wick layer uses high thermal conductivity material in regions where heat transfer efficiency is prioritized. This local quality approach resolves the contradiction by allowing optimal properties in different locations.
2Object-affected harmful factors
If a single layer of wick structure with high thermal conductivity is used to reduce local thermal resistance, then local thermal resistance is reduced, but initialization becomes extremely difficult requiring extremely high critical power
Solution Approach 1:
The wick structure is segmented into two layers with different thermal conductivity characteristics. The first layer provides the necessary capillary force for initialization with appropriate resistance, while the second layer ensures low local thermal resistance for efficient heat transfer during operation. This segmentation eliminates the need for extremely high critical power while maintaining good thermal contact.
Solution Approach 2:
The dual-layer wick structure combines materials with different thermal conductivity properties. The first wick layer uses material with lower thermal conductivity to provide capillary action and prevent premature heat leak, while the second layer uses material with higher thermal conductivity to ensure efficient heat transfer. This composite structure balances initialization requirements with operational performance.
3Use of energy by moving object
If the evaporator bottom is made of high thermal conductivity material to improve heat transfer from heat source, then heat transfer from heat source is improved, but heat transferred to reservoir via wall portions increases
Solution Approach 1:
The evaporator structure is designed with spatially varying thermal conductivity properties. The bottom portion uses high thermal conductivity material to maximize heat absorption from the heat source, while the wall portions use low thermal conductivity material to minimize heat transfer to the reservoir. This local quality differentiation allows the system to optimize heat transfer where needed while preventing energy loss in other regions.
Solution Approach 2:
The evaporator is segmented into functional zones with different thermal properties. The bottom region is optimized for heat absorption with high thermal conductivity material, while the wall regions are optimized for heat isolation with low thermal conductivity material. This segmentation resolves the contradiction by allowing high heat transfer efficiency at the heat source interface while preventing parasitic heat transfer to the reservoir through the walls.
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
The solution effectively prevents heat leak and reduces pressure loss, ensuring efficient heat dissipation and normal operation of the loop heat pipe structure under various conditions, including standard and no-gravity scenarios, with improved thermal performance and reduced local thermal resistance.
Implementation Method 1
a first wick layer 121 located atop the bottom 125... The above-described first wick layer provides sufficient capillary force required by the whole loop heat pipe structure to work normally, and reduces the pressure loss caused by the movement of the working fluid through the first wick layer
Implementation Method 2
a second wick layer 122 located atop and covers the first wick layer 121... The above-described second wick layer serves as a heat lock layer to effectively prevent the heat transferred to the first wick layer from entering into the second chamber to cause heat leak
Implementation Method 3
A loop heat pipe structure with a first wick layer providing sufficient capillary force and a second wick layer acting as a heat lock layer, combined with grooves on either the wick layer or the evaporator's bottom, to prevent heat from entering the reservoir and reduce pressure loss, thereby avoiding high vapor pressure and enhancing overall heat dissipation efficiency
Implementation Method 4
the working fluid will not be overheated to form vapor-liquid phase equilibrium and produce high saturation vapor pressure in the second chamber, allowing the liquid-phase working fluid in the transport pipe to return to the second chamber
Data Source
AI summary
A loop heat pipe structure includes a transport pipe, an evaporator, a first wick layer, a second wick layer, and a plurality of grooves. The transport pipe communicates with the evaporator. The evaporator has a bottom and internally defines a first chamber and a second chamber, and has a working fluid filled therein. The first wick layer is located on the bottom, and the second wick layer is located on and covers the first wick layer. The grooves can be selectively provided on the first wick layer or the bottom. The first and second wick layers are so designed that the situation of very high vapor pressure would not occur in the second chamber, enabling the loop heat pipe structure to have upgraded heat dissipation efficiency.