Heat Pipe Thermal Conduction Pillars for Boiling Limit
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Solution Overview
Problem
Current grooved heat pipes, particularly reentrant groove heat pipes, face limitations in their boiling limit, which restricts their operational capacity and efficiency, especially under terrestrial conditions where gravity affects the liquid phase return, leading to issues like bubble congestion and overheating.
Innovation Solution
The design incorporates thermal conduction pillars extending into the vapor channel to directly apply heat to the liquid-vapor interface, potentially using reentrant grooves or a porous media, to enhance evaporation without increasing vapor phase pressure loss, and employs advanced manufacturing methods like selective laser sintering for improved structural integrity and fluid continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat is applied to the evaporator wall in conventional grooved heat pipes, then heat transfer occurs, but bubble congestion blocks vapor escape and reduces boiling limit
Solution Approach 1:
The patent introduces thermal conduction pillars as intermediary elements that extend from the evaporator wall into the vapor channel, positioned adjacent to the liquid-vapor interface. These pillars serve as mediators to conduct heat directly to the interface region where bubbles form, enabling localized heating that promotes bubble escape without requiring high heat flux at the wall, thereby reducing bubble congestion and increasing the boiling limit.
Solution Approach 2:
The thermal conduction pillars create localized heat transfer zones at the liquid-vapor interface rather than uniform heating of the entire evaporator wall. This local quality approach concentrates thermal energy precisely where needed (at the interface to facilitate bubble departure) while maintaining lower overall heat flux, thus improving the boiling limit without exacerbating bubble congestion throughout the evaporator.
2Temperature
If thermal conduction pillars are added to the evaporator, then heat transfer to liquid-vapor interface is improved, but device complexity increases
Solution Approach 1:
The patent describes embodiments where the thermal conduction pillars can be implemented as a porous medium or foam structure within the vapor channel. This porous material provides extensive surface area for heat conduction to the liquid-vapor interface while occupying minimal space and integrating seamlessly with the existing evaporator geometry, thus improving heat transfer efficiency without proportionally increasing device complexity.
Solution Approach 2:
The thermal conduction pillars are described as potentially being made from composite materials or integrated with the evaporator wall through bonding or brazing techniques. This composite approach allows the pillars to be manufactured as part of the evaporator assembly rather than as separate components, reducing overall device complexity while maintaining the heat transfer enhancement function.
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 approach increases the boiling limit without compromising capillary pumping efficiency or thermal conductance, allowing for higher thermal power transfer and improved operational reliability across a broader temperature range.
Implementation Method 1
a plurality of uprights forming thermal conduction pillars which extend at least in the vapor channel in a second direction (Y) orthogonal to the first direction (X), from a lateral face of the enclosure from which the flow coming from the hot source is applied, up to the liquid-vapor interface
Implementation Method 2
Grooved heat pipes operate on the principle of capillary pumping... Due to a change in curvature of the liquid-vapor interface between the condenser zone and the evaporator zone, a pressure gradient appears in the liquid, which leads to a change in capillary pressure
Implementation Method 3
an equilibrium is established between the liquid phase and the vapor phase... part of the liquid phase vaporizes and absorbs the heat flux in latent form by inducing a slight overpressure which causes the movement of the vapor towards an area at the other longitudinal end, called the condenser
Implementation Method 4
At the condenser, the vapor condenses and returns to the liquid phase
Implementation Method 5
an equilibrium is established between the liquid phase and the vapor phase... part of the liquid phase vaporizes... At the condenser, the vapor condenses and returns to the liquid phase
Data Source
Figure 1~2
Figure 3A~3C
Figure 4~4A
AI summary
The invention relates to a heat pipe (1) extending along a first longitudinal direction (X), comprising a sealed enclosure (2) extending between a first longitudinal end (3), intended to be heated by a hot source SC to form, within the enclosure, an evaporator (ZE) and a second longitudinal end (4) intended to be cooled by a cold source SF to form a condenser (ZC), the sealed enclosure delimiting an adiabatic zone (ZA) between the evaporator and the condenser, the evaporator comprising a vapor channel (13), at least one liquid channel (11) connected to the vapor channel by defining at least one liquid-vapor interface (I), and a plurality of uprights (15) forming thermal conduction pillars which extend at least into the vapor channel in a second direction (Y) orthogonal to (X), from a lateral face (21) of the enclosure from which the flow from the hot source is applied,up to the liquid-vapor interface.