Loop Heat Pipe Wick Structure for Low Pressure Loss Cooling
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Solution Overview
Problem
In loop heat pipes, the wick structure used for transporting working fluid faces a paradox where increasing capillary force to enhance cooling efficiency is hindered by increased pressure loss, making it difficult to efficiently transport fluid and cool the heat generator effectively.
Innovation Solution
The cooling device incorporates a wick with through holes penetrating from a reservoir to a groove member, featuring a layered structure with a higher void ratio and thermal conductivity in the second layer, allowing efficient fluid transport and phase change, reducing pressure loss while maintaining capillary force, and a protruding part to communicate holes and flow channels, ensuring unobstructed fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the void diameter of the wick is reduced to increase capillary force, then the maximum capillary force increases, but the permeability of the working fluid decreases and pressure loss increases
Solution Approach 1:
The wick is divided into multiple layers with different void ratios. The first layer has a smaller void ratio for high capillary force, while the second layer has a larger void ratio for low pressure loss. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between capillary force and pressure loss.
Solution Approach 2:
Different regions of the wick are given different properties. The first layer near the heat source has small voids for strong capillary action, while the second layer farther away has large voids for efficient fluid transport with minimal resistance. This local differentiation resolves the contradiction by matching structure to function at each location.
2Ease of operation
If the void diameter is small to increase capillary force, then the working fluid can be transported, but the pressure loss increases reducing transportation efficiency
Solution Approach 1:
The wick structure is segmented into two layers: the first layer with small voids for capillary-driven fluid uptake, and the second layer with large voids for low-resistance fluid transport to the groove member. This segmentation enables efficient fluid transportation while minimizing pressure loss.
Solution Approach 2:
The void ratio parameter is changed between layers - the first layer has a smaller void ratio (0.3-0.6) for capillary action, while the second layer has a larger void ratio (0.6-0.8) for reduced pressure loss. This parameter optimization resolves the contradiction between transportation efficiency and pressure loss.
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 enhances the cooling efficiency of the heat source by reducing pressure loss and promoting phase change, leading to improved heat transfer and efficient cooling of the heat generator.
Implementation Method 1
The working fluid in the liquid phase soaks into the large number of small holes from the liquid reservoir section inside the housing due to a capillary action
Implementation Method 2
The evaporator evaporates the working fluid in the liquid phase with the heat of the heat generator
Implementation Method 3
evaporate a working fluid in a liquid phase with a heat transferred from a cooling target to change the working fluid in the liquid phase to the working fluid in a gas phase
Implementation Method 4
The condenser condenses the working fluid in the gas phase due to heat radiation to perform a phase change from the working fluid in the gas phase to the working fluid in the liquid phase
Data Source
AI summary
A cooling device is provided with an evaporator, a condenser, a vapor pipe, and a liquid pipe. The evaporator includes a housing having a reservoir configured to retain a working fluid in a liquid phase flowing inside, a wick disposed in the housing, and transporting the working fluid in the liquid phase, and a groove member having a plurality of flow channels through which the working fluid changed in phase from the liquid phase to the gas phase flows, the groove member being coupled to the wick. The wick has a plurality of through holes which penetrate the wick along a first direction from the reservoir toward the groove member, the through holes being configured to transport the working fluid in the liquid phase retained in the reservoir in the first direction.