Multi-layer wick for loop heat pipe thermal management

Solution Overview

Problem

Loop heat pipes experience heat leakage and increased heat transfer resistance due to the high thermal conductivity of metal primary wicks and the low thermal conductivity of ceramic wicks used in their structures, which affect the efficiency of heat transfer.

Innovation Solution

A multi-layer wick structure is introduced, comprising a primary wick with a high thermal conductivity first layer surrounding a low thermal conductivity second layer, and a secondary wick, which reduces heat leakage and enhances heat transfer by optimizing the thermal conductivity and insulation within the wick structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal primary wick is used, then heat transfer efficiency is improved, but heat leakage increases

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidheat leakage

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The primary wick is divided into two separate layers: an inner layer made of metal material for efficient heat transfer, and an outer layer made of ceramic material for thermal insulation. This segmentation allows each layer to perform its specific function optimally without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a composite structure combining metal and ceramic materials in the primary wick. The metal inner layer provides high thermal conductivity for efficient heat transfer, while the ceramic outer layer provides thermal insulation to prevent heat leakage to the compensation chamber.

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If a ceramic primary wick is used, then heat leakage is reduced, but heat transfer resistance increases

Engineering Contradiction:

Improveheat leakageVSAvoidheat transfer efficiency

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The primary wick is divided into two separate layers: an inner layer made of metal material for efficient heat transfer, and an outer layer made of ceramic material for thermal insulation. This segmentation allows each layer to perform its specific function optimally without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the primary wick are assigned different material properties: the inner layer uses metal material with high thermal conductivity for efficient heat transfer, while the outer layer uses ceramic material with low thermal conductivity for thermal insulation. Each local region has optimized quality for its specific function.

Inventive Principle:

Principle #3Local quality

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 multi-layer wick structure effectively reduces heat leakage from the evaporator to the compensation chamber while increasing heat transfer efficiency by balancing thermal conductivity and insulation, thereby minimizing temperature differences and thermal resistance.

Implementation Method 1

The multi-layer wick structure effectively reduces heat leakage from the evaporator to the compensation chamber while increasing heat transfer efficiency by balancing thermal conductivity and insulation

Methodology Applied

Scientific EffectThermal conductivity: Conduction (thermal)

Implementation Method 2

Capillary forces accomplish this passively, sucking liquid back to the surface, just as water will be sucked up into a sponge

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 3

Loop heat pipes are two-phase heat transfer devices that utilize the evaporation and condensation of a working fluid to transfer heat

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 4

Saturated vapor 8 flows through vapor grooves in evaporator 4 and merges into a vapor line 10 and a condenser 12 where heat is removed

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS8720530B2Multi-layer wick in loop heat pipe

Publication Date: 2014.05.13 THE BOEING CO

AI summary

In one aspect of the present invention, a multi-layer wick for a loop heat pipe is provided. The multi-layer wick includes a primary wick, the primary wick comprising: a first layer; and a second layer, wherein the first layer surrounds the second layer; and a secondary wick, wherein the second layer of the primary wick surrounds the secondary wick.In another aspect of the present invention, a method of fabricating a multi-layer wick is provided. The method includes machining the outer diameter of an inner layer larger than the inner diameter of an outer layer; heating the outer layer to enlarge the inner diameter; inserting the inner layer into the outer layer; and cooling the inner layer and the outer layer.