Capillary Pumped Micro Loop With Insulating Sleeve

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Solution Overview

Problem

Heat transfer loops with capillary pumping face inefficiencies due to parasitic heating of the liquid transfer fluid, which degrades thermal performance and can lead to loop shutdown, especially in high-power density electronic components with significant temperature gradients.

Innovation Solution

A passive thermal regulation device with a heat transfer loop featuring a microporous mass evaporator and condenser, where the liquid phase is pumped through a thermally insulating sleeve to prevent parasitic heat fluxes, and the vapor phase is evacuated through a central duct, ensuring efficient heat transfer and minimizing fluid heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the liquid reserve is positioned close to the evaporator for efficient capillary pumping, then the fluid circulation is improved, but parasitic heating of the liquid increases degrading thermal performance

Engineering Contradiction:
Improvefluid circulation efficiencyVSAvoidthermal performance
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The microporous mass is divided into two distinct zones: a first zone in thermal contact with the hot source for vapor generation, and a second zone thermally isolated for liquid reservoir function. This segmentation allows the liquid reserve to be positioned adjacent to the evaporator for efficient capillary pumping while preventing parasitic heating through the thermal barrier between zones.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A thermal barrier or insulating structure is introduced between the hot source/evaporator zone and the liquid reserve zone. This intermediary element blocks parasitic heat fluxes from heating the liquid while allowing capillary forces to continue pumping the liquid efficiently from the reserve through the microporous mass.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If the microporous mass is extended to improve heat transfer surface area, then thermal performance improves, but parasitic heat fluxes to the liquid reserve increase

Engineering Contradiction:
Improveheat transfer capacityVSAvoidparasitic heating
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

Different regions of the microporous mass are assigned different thermal characteristics: the first zone has high thermal conductivity to the hot source for maximum heat transfer capacity, while the second zone has low thermal conductivity to prevent parasitic heating. This local differentiation allows extended surface area without proportional increase in parasitic heat fluxes.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The extended microporous mass is segmented into functional zones with different thermal isolation properties, allowing the overall heat transfer surface area to be increased while specific zones maintain thermal barriers to prevent parasitic heating of the liquid reserve.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If the loop is miniaturized for electronic component cooling, then application versatility improves, but thermal management efficiency decreases due to parasitic heating effects

Engineering Contradiction:
Improveapplication rangeVSAvoidthermal regulation efficiency
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The miniaturized loop incorporates a segmented microporous mass with thermally isolated zones, enabling the system to maintain high thermal regulation efficiency in a compact form factor suitable for electronic component cooling applications.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A thermal barrier is introduced within the miniaturized loop structure to prevent parasitic heating of the liquid reserve, thereby maintaining thermal management efficiency despite the reduced scale and increased surface-to-volume ratio characteristic of miniaturized systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 design enhances thermal performance by reducing parasitic heating and maintaining fluid flow, thereby improving the reliability and efficiency of thermal regulation for high-power density electronic components.

Implementation Method 1

a microporous mass, which ensures the circulation of heat transfer fluid in the liquid phase by capillary pumping

Methodology Applied
Scientific EffectCapillary pumping: Capillary Action

Implementation Method 2

The fluid in liquid phase present in the reserve associated with the evaporator evaporates in the microporous mass under the effect of the heat coming from the hot source

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

The fluid in liquid phase present in the reserve associated with the evaporator evaporates in the microporous mass under the effect of the heat coming from the hot source. The gas thus created

Methodology Applied
Scientific EffectPhase change: Phase Change

Implementation Method 4

where it condenses and returns in the liquid phase to the evaporator, thus creating a heat transfer cycle

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 5

the first longitudinal part penetrating inside a thermally insulating sleeve located in a portion of said external tube

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP2179240B1Passive device with capillary pumped fluidic micro loop
Publication Date: 2011.05.18 ASTRIUM SAS
  • EP2179240B1 patent drawingFigure 1~4
  • EP2179240B1 patent drawingFigure 2~3
  • EP2179240B1 patent drawingFigure 5~6

AI summary

Each loop (1) of the device includes an evaporator (2) and a condenser (3) connected by an outer tube (6) in a portion of which extends a thermally insulating sleeve (9) having one end (9b) that can lead into the condenser (3) and another end (9a) that surrounds a first portion (8a) of a microporous mass (8) provided in the outer tube (6) and pumping by capillarity a liquid-phase heat-carrier fluid flowing in the insulating sleeve (9) of the condenser (3) towards the evaporator (2), while the gaseous-phase fluid flows from a vapour-collecting central duct (25) in a second portion (8b) of the mass (8) of the evaporator (2) towards the condenser (3) in a duct (11) inside said outer tube (6). The invention can be used for the thermal energy transfer from an electronic component or circuit defining a heat source (4) in relation with the evaporator (2) to a cold source (5) in relation with the condenser (3).