Heat Pipe Design and Technology: Modern Applications for Practical Thermal Management

539 Pages·2016·11.29 MB·English

by  Bahman Zohuri (auth.)

Bahman Zohuri
Heat Pipe
Design and
Technology
Modern Applications for Practical
Thermal Management
Second Edition
Heat Pipe Design and Technology

Bahman Zohuri
Heat Pipe Design
and Technology
Modern Applications for Practical Thermal
Management
Second Edition
BahmanZohuri
GalaxyAdvancedEngineering,Inc.
Albuquerque,NM,USA
ISBN978-3-319-29840-5 ISBN978-3-319-29841-2 (eBook)
DOI10.1007/978-3-319-29841-2
LibraryofCongressControlNumber:2016932886
©SpringerInternationalPublishingSwitzerland2011,2016
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This book is dedicated to my wife Firouzeh,
my daughters Natasha and Natalie, and son
Sasha
I am also dedicating this book to my mother
Marzieh and father Akbar
without their individual encouragement, this
book would not have been written.

Preface for the Second Edition
Now that the second edition of this book is out, the reader will need to know
additional information and improvements that are in this edition. First of all, the
errorsfoundinthefirsteditionwerecorrectedandcertainsectionswereeliminated
when there was no need for them based on the input from kind readers such as
MahboobeMahdaviandSaeedTiari.
A complete section was added to Chap. 4 entitled “Heat Pipe Applications in
Thermal Energy Storage Systems” including all the subsections, which were
graciously provided by Mahboobe Mahdavi and Saeed Tiari of the Mechanical
Engineering Department of Temple University at Philadelphia, Pennsylvania,
where further applications of heat pipes are identified along with Concentrated
Solar Power (CSP) system. CSP recently has shown a great potential as part of
renewableenergyinfrastructure.
The heat pipe is one of the remarkable achievements of thermal physics and
heat-transfer engineering in this century because of its unique ability to transfer
heatoverlargedistanceswithoutconsiderablelosses.Themainapplicationsofheat
pipes deal with the problems of environmental protection and energy and fuel
savings.
Heat pipes have emerged as an effective and established thermal solution,
particularly in high heat flux applications and in situations where there is any
combinationofnon-uniformheatloading,limitedairflowovertheheat-generating
components,andspaceorweightconstraints.Thisbookwillbrieflyintroduceheat
pipe technology and then highlight its basic applications for passive thermal
control.
After a review of heat and mass transfer theory relevant to heat pipe perfor-
mance,mathematicalmodelsaredevelopedforcalculatingheat-transferlimitations
of high-temperature heat pipes and heat-transfer limitations and temperature gra-
dient of low-temperature heat pipes. Calculated results are compared with the
available experimental data from various sources to increase confidence in the
presentmathematicsmodels.
vii
viii PrefacefortheSecondEdition
Fortheconvenienceoftheusersofthepresenttheory,afewcomputercodesand
their application are mentioned and they are available from Galaxy Advanced
Engineering, Inc. These codes are designedto handle interactive input from users
ofthecodes,andtwocomputerprogramsforhigh-andlowtemperatureheatpipes
respectively are reported. These programs enables the performance of wrapped-
screen heat pipes, rectangular-groove heat pipes, or screen-covered rectangular-
groovewicktobepredicted.Thesecodesareespeciallyhelpfulindesignofsteady-
stateheatpipeandareexecutableonWindow/PCcomputingplatforms.
Additionally,whenevertheauthorfindstheneedtounderstandthebasicphysics
and mathematics and for those readers to refresh their knowledge, sections of
Wikipedia are presented in this book to further clarify certain complexities and
advanced approaches for different equations and description of various topics on
physicsoffluidmechanics,heattransfer,andgasdynamics.
Heatpipetechnologyispertinenttothedesignandapplicationofself-controlled,
variableconductanceheatpipesforspacecraftthermalcontrolisdiscussed.Inves-
tigations were conducted to (1) provide additional confidence in existing design
tools, (2) to generate new design tools, and (3) to develop superior variable
conductance heat pipe designs. A computer program for designing and predicting
theperformanceoftheheatpipesystemswasdeveloped.
Withinthisbookacomprehensivereviewandanalysisofallaspectsofheatpipe
technologypertinenttothedesignofself-controlled,variableconductancedevices
forspacecraftthermalcontrolisalsopresented.Subjectsconsideredincludehydro-
statics, hydrodynamics, heat transfer into and out of the pipe, fluid selection,
materials compatibility, and variable conductance control techniques. Also
includedisadiscussionofVCHPdesigntechniques.
A variable-conductance heat pipe system (VCHPS) and its design have been
discussed, and various references have been identified for further information to
provide athermal controlfor atransmitterexperiment package (TEP) tobeflown
ontheCommunicationsTechnologySatellite.TheVCHPSprovidesheatrejection
duringTEPoperationandminimizestheheatleakduringpowerdownoperations.
TheVCHPSdescribedfeaturesauniquemethodofaidingprimingofarterialheat
pipesandanovelapproachtobalancingheatpipeloadsbystaggeringtheircontrol
ranges.
This book introduces operational and design principles for heat pipes. A heat
pipeisessentiallyapassivedevicethatcanquicklytransferheatfromonepointto
another.Theyareoftenreferredtoasthe“superconductors”ofheatastheypossess
anextraordinaryheat-transfercapacityandratewithalmostnoheatloss.Theheat
transferredfromthehotsourceevaporatesthefluidinthewick,causingthevaporto
expand into the center core of the heat pipe. The latent heat of vaporization is
carried with the vapor to the cold end of the tube, where it is removed by
transferencetotheheatsinkasthevaporcondenses.Thecondensateisthencarried
backinthewicktothehotendofthetubebycapillaryactionandbygravity(ifthe
tubeistiltedfromthehorizontal),whereitisrecycled.Thistwo-phaseheat-transfer
mechanismresultsinheat-transfercapabilitiesfrom100toseveralthousandtimes
thatofanequivalentpieceofcopper.
PrefacefortheSecondEdition ix
The heat pipe is compact and efficient because (1) the finned-tube bundle is
inherently a good configuration for convective heat transfer in both ducts and
(2) the evaporative-condensing cycle within the heat pipes is a highly efficient
methodoftransferringheatinternally.
The effects of different factors on the performance of the heat pipe—compati-
bilityofmaterials,operatingtemperaturerange,diameter,powerlimitations,ther-
malresistances,andoperatingorientation—willbeconsideredinthebook.
Heat pipescanbedesigned tooperateover averybroad rangeoftemperatures
from cryogenic (less than 30 K) applications to high temperature systems (more
than2000K).Untilrecently,theuseofheatpipeshasbeenmainlylimitedtospace
technologyduetoitscost-effectivenessandcomplexwickconstruction.Thereare
several applications of heat pipes in this field, such as spacecraft temperature
equalizationcomponentcooling,temperaturecontrol,andradiatordesigninsatel-
lites. Currently heat pipe technology has been integrated into modern thermal
engineeringdesigns,suchasterrestrialthermalcontrolsystems,solarenergetic,etc.
The increasing power and shrinking size of electronic components presents
growing thermal management challenges. While solid metal conductors such as
aluminumextrusionsmayprovideacceptablecoolingforindividualcomponentsin
certain situations, broad-level solutions with more advanced cooling technologies
areneededinagrowingnumberofapplications.
After a review of heat and mass transfer theory, relevant to heat pipe perfor-
mance,mathmodelsaredevelopedforcalculatingheat-transferlimitationsofhigh-
temperature heat pipes and heat-transfer limitations and temperature gradient of
low-temperature heat pipes. Calculated results are compared with the available
experimentaldatafromvarioussourcestoincreaseconfidenceinthepresentmath
models.
Fortheconvenienceoftheusersofthepresenttheory,completelistingsoftwo
computer programs for high- and low-temperature heat pipes respectively are
appendedtothebook.
These programs enables the performance of wrapped-screen heat pipes,
rectangular-groove heat pipes, or screen-covered rectangular-groove wick to be
predicted.
Few more computer programs are also mentioned, and some are obtainable
either from US government organization or from Galaxy Advanced Engineering,
Inc.orfromothercommercialcompaniesthathelpinthedesignofsteady-stateheat
pipeand,mostofthem,areexecutableonWindow/PCcomputingplatform.These
codesareadditionalhelpforreaderstocalculateworkingfluidproperties.Theyalso
assist heat-transfer analysis for design of fins for both constant and variable heat
pipes.Inaddition,Excelspreadsheetsthatevaluateanalyticalsolutionsoffourview
factor geometries (perpendicular and rectangular shape with a common edge,
coaxial parallel disks, coaxial cylinders, and aligned parallel rectangles) may be
downloaded from Galaxy Advanced Engineering website at www.gaeinc.com,
pleasecontactthiscompany.
Avariable-conductanceheatpipesystem(VCHPS)hasbeendesignedtoprovide
thermal control for a transmitter experiment package (TEP) to be flown on the