Miniature Loop Heat Pipes for Electronics Cooling Research Review

Essential VocabularyTwo-phaseLatent heat Surface tension CapillarityViscosityHeat flux

What is Loop heat pipes Two-phase heat transfer device that

operates on the basis of a capillary driven loop

Background Challenges of cooling computer components

Small heating area Space limitationMaintaining temperature below 100°C

AchievementsCylindrical evaporator with ammonia as coolant (25-30W)Flat evaporators

Ammonia and stainless steel (87W)Ethanol and nickel wick (120W) Research based of water-copper configuration ( 130-160W)

Research Goal Study further the development and capability of Miniature LHP (mLHP)

Meet computer development

Consideration of miniaturizing LHP Overcome space limitation

Testing water-copper configurationReach cooling below 100°C

Study ConditionsFlat evaporator- 30 mmTransport 70 WLoop length of 150 mmWater as coolant

Method DescriptionNon-uniform heating area (3/5)Thermocouple readings- every 10 secondsForced convention- fan Testing was done in the horizontal configurationmLHP thermal performance measured:

Max heat capacity Evaporator temperature Total thermal resistance

Assembly Description

Experiment Method

Results DiscussionReliable startup and steady state at low and high power

Results DiscussionsCapability to transfer 70W at around 100CmLHP auto-regulate the evaporator temperature

Results Discussions Decrease of HP thermal resistance (merit number, liquid distribution)

Observation Capability of handling non-uniform heat distribution

Consideration of other positions than symmetricalAssumption of capability of uniform distribution

Measurement of heat load was not indicated Consideration of angled configurationConducting the test in an enclosure/confinement

References