Loop Heat Pipe Evaporator Structure for Tilted Cooling Uniformity
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Solution Overview
Problem
Miniaturized electronic devices in transportation machines face uneven cooling due to position changes, leading to decreased heat transport rates and localized dry portions in evaporators that do not maintain thermal contact with the heat generator.
Innovation Solution
An evaporator design with a housing divided into upper and lower chambers by a porous plate, featuring a heat receiver at the bottom, liquid retainers, and controlled fluid flow through pores to ensure even distribution of the working fluid across the heat receiver, maintaining thermal contact even when tilted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the evaporator is tilted or positioned in different orientations, then the working fluid can still reach the heat receiver through gravity and capillary action, but the working fluid may not maintain uniform contact with the heat receiver surface, creating dry portions that reduce cooling efficiency
Solution Approach 1:
The patent employs a porous wick material that utilizes capillary action to distribute the working fluid uniformly across the heat receiver surface. The porous structure allows the fluid to be drawn through the material and spread evenly, ensuring that no dry portions form on the heat receiver surface regardless of the evaporator's orientation. This resolves the contradiction by maintaining cooling uniformity through capillary-driven fluid distribution while accommodating various positions.
Solution Approach 2:
The porous wick acts as an intermediary between the working fluid reservoir and the heat receiver surface. It mediates the fluid distribution process by absorbing fluid from the reservoir and delivering it uniformly across the heat receiver through capillary forces, ensuring consistent thermal contact even when the system is tilted or positioned differently.
2Ease of manufacture
If the evaporator uses a simple liquid reservoir design, then the structure is simple and easy to manufacture, but the working fluid distribution across the heat receiver becomes uneven when the position changes
Solution Approach 1:
The patent introduces a porous wick material that can be easily integrated into the liquid reservoir structure. This porous layer is positioned between the fluid reservoir and the heat receiver, and it automatically distributes the working fluid uniformly through capillary action without requiring complex mechanical structures, pumps, or control systems. The solution maintains ease of manufacture while significantly improving fluid distribution uniformity.
3Use of energy by moving object
If the evaporator is designed with a heat receiver at the bottom, then gravity assists fluid return to the heat receiver, but tilting the evaporator causes the liquid to move away from certain areas of the heat receiver, creating dry portions
Solution Approach 1:
The porous wick material compensates for the effects of tilting by utilizing capillary action to distribute the working fluid across the entire heat receiver surface, including areas that would otherwise become dry due to gravitational separation. The capillary forces in the porous material are sufficient to overcome the gravitational component acting perpendicular to the heat receiver surface, ensuring uniform fluid coverage and maintaining thermal contact even when tilted.
Solution Approach 2:
The patent replaces reliance on pure gravitational flow with capillary action in the porous wick material. Instead of depending on gravity to maintain fluid contact with the heat receiver surface during tilting, the system uses the capillary forces inherent in the porous structure to actively distribute the fluid, substituting a passive gravitational system with an active capillary-driven system.
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
Ensures efficient cooling of the heat generator by distributing the working fluid evenly across the heat receiver, preventing dry portions and maintaining thermal contact despite changes in position, thus enhancing heat transport efficiency.
Implementation Method 1
a porous plate dividing the accommodation chamber into an upper chamber and a lower chamber and including a large number of pores through which the upper and lower chambers communicate with each other
Implementation Method 2
the heat receiver is thermally connected to the heat generator... the working fluid in a liquid phase is heated by heat transferred from a heat generator, and a part of the working fluid changes into a gas phase
Implementation Method 3
heat transferred from a heat generator
Implementation Method 4
The gas-liquid two-phase working fluid moves in the vapor conduit under the action of pressure difference and buoyancy and reaches the condenser
Implementation Method 5
The gas-liquid two-phase working fluid moves in the vapor conduit under the action of pressure difference and buoyancy
Implementation Method 6
In the condenser, the working fluid is cooled into the liquid phase
Implementation Method 7
The liquid-phase working fluid returns to the evaporator under the action of capillary force and/or gravity
Implementation Method 8
The liquid-phase working fluid returns to the evaporator under the action of capillary force and/or gravity
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An evaporator that receives heat from a heat generator to change at least part of a working fluid from a liquid phase to a gas phase includes: a housing including an accommodation chamber that accommodates the working fluid; and a heat receiver located on a bottom surface of the housing and thermally connected to the heat generator. The housing includes: a porous plate dividing the accommodation chamber into an upper chamber and a lower chamber and including a large number of pores through which the upper and lower chambers communicate with each other; at least one working fluid inlet opening into the upper chamber; a partition dividing a bottom of the lower chamber into liquid retainers; and at least one working fluid outlet opening into the lower chamber and located above the partition.