Loop Heat Pipe Evaporator Layout for Tilt-Stable Vapor Flow
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Solution Overview
Problem
Miniaturized electronic devices in transportation machines face reduced heat transport efficiency due to position changes, which disrupt the flow of working fluid in loop heat pipes using gravity for circulation, leading to decreased drive force and heat transport rates.
Innovation Solution
An evaporator design with working fluid outlets located at or above an imaginary liquid surface, ensuring smooth fluid flow regardless of position changes, and a loop heat pipe configuration that maintains circulation stability by positioning outlets strategically to avoid tilting-induced disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the working fluid outlet is positioned in the upper portion of the side surface (conventional design), then the structure is simple, but tilting causes the outlet to be below the liquid surface, reducing flow rate and heat transport rate
Solution Approach 1:
The patent transitions the outlet position from the side surface to the top surface of the evaporator housing. This dimensional change ensures that the outlet remains above the liquid surface even when the evaporator is tilted, as the top surface maintains its upward orientation relative to gravity. The outlet is specifically positioned at a corner of the top surface to optimize fluid discharge while accommodating tilt angles up to 45 degrees.
Solution Approach 2:
The outlet is pre-positioned on the top surface at an angle θ of 45 degrees or more relative to the horizontal direction. This preliminary angular positioning ensures that regardless of the tilt occurrence, the outlet maintains a sufficient upward orientation to prevent submersion in the liquid phase, thereby maintaining reliable vapor discharge and heat transport performance.
2Adaptability or versatility
If the evaporator is tilted in transportation machines, then adaptability to different positions is improved, but the drive force for working fluid circulation decreases
Solution Approach 1:
By repositioning the outlet from the side to the top surface, the design creates a geometric configuration where the outlet corner maintains its elevation above the liquid surface during tilting. This dimensional repositioning preserves the gravitational drive force for vapor rise and fluid circulation even when the evaporator is tilted at angles up to 45 degrees, enabling adaptability to various transportation machine positions.
3Adaptability or versatility
If the working fluid outlet is below the liquid surface due to tilting, then position flexibility is improved, but the flow rate of working fluid decreases
Solution Approach 1:
The outlet is pre-configured on the top surface with a specific angular orientation (θ ≥ 45 degrees) that anticipates potential tilting conditions. This preliminary positioning ensures that the outlet remains in the vapor phase region during operation, maintaining high flow rates by preventing liquid submersion that would otherwise block or reduce vapor discharge and diminish circulation speed.
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 ensures continuous and stable heat transport in transportation machines by preventing disruptions in working fluid flow, maintaining efficiency even when the evaporator is tilted within its allowable angle, thus addressing the issue of reduced heat transport rates caused by position changes.
Implementation Method 1
the working fluid in a liquid phase is heated by heat transferred from a heat-generating element, and a part of the working fluid changes into a gas phase
Implementation Method 2
heat transferred from a heat-generating element
Implementation Method 3
The gas-liquid two-phase working fluid moves in the vapor conduit under the action of pressure difference and buoyancy
Implementation Method 4
The gas-liquid two-phase working fluid moves in the vapor conduit under the action of pressure difference and buoyancy
Implementation Method 5
The liquid-phase working fluid returns to the evaporator under the action of capillary force and/or gravity
Data Source
AI summary
An evaporator includes: a housing having a plurality of surfaces including a front surface and a back surface, at least one of the front and back surfaces having the largest area among the plurality of surfaces; and a heat-absorbing element disposed on at least one of the front and back surfaces and thermally connected to a heat source. The housing includes: at least one working fluid inlet located in a surface of the housing, the surface being other than a top surface of the housing; and at least one pair of working fluid outlets located respectively in opposite longitudinal end portions of the top surface.