Kasra Nakhaee

Contents

• Introduction………………………………………………………………………………. 3

• Principle of Heat Pipe operation………………………………………………… 4

• Heat Pipe Types…………………………………………………………………………. 10

• HPHXs & Applications………………………………………………………………… 28

• HPHX Types……………………………………………………………………………..... 31

• References…………………………………………………………………………………. 40

Kasra Nakhaee - November 2015 2

Introduction

• Heat pipe concept described in 1942

• ‘Heat Pipe’ term was used in 1963

• High heat transport characteristics due to Use of Latent Heat

• No Energy Required for its Operation

• It was developed originally for the gravity-free environment

• Increasing usage in many industrial applications


• HP consists:

• Closed container

• Working fluid

• Porous capillary wick

• One end functions as evaporator

• The other end functions as condenser

• P = Psat at its operating temperature


Principle of Heat Pipe operation



• Thermodynamic cycle:

• 1-2 Heat applied to evaporator through external sources vaporizes working

fluid to a saturated(2’) or superheated (2) vapor.

• 2-3 Vapor pressure drives vapor through adiabatic section to condenser.

• 3-4 Vapor condenses, releasing heat to a heat sink.

• 4-1 Capillary pressure created by menisci in wick pumps condensed fluid into

evaporator section.

• Process starts over.



• Thermodynamic cycle:



• Limits:

• Wicking

• Entrainment

• Sonic

• Boiling

• Flooding





MEDIUMMELTING PT. (° C )

BOILING PT. AT ATM. PRESSURE

(° C)

USEFUL RANGE

(° C)

Helium

Ammonia

Water

Silver

- 271

- 78

0

960

- 261

- 33

100

2212

-271 to -269

-60 to 100

30 to 200

1800 to 2300

a) Tow-Phase Closed Thermosyphon

b) Capillary-Driven Heat Pipe

c) Annular Heat Pipe

d) Vapor Chamber

e) Rotating Heat Pipe

f) Gas-Loaded Heat Pipe

Heat Pipe Types


g) Loop heat pipes (LHP)

h) Capillary Pumped Loop Heat Pipe

i) Pulsating heat pipes (PHP)

j) Micro and Miniature Heat Pipe

k) Inverted Meniscus Heat Pipe

l) Nonconventional Heat Pipe

Heat Pipe Types


Heat Pipe Types


a) Two-Phase closed Thermosyphon:

• Gravity-assisted wickless

• Sonic and vapor pressure limit

• Flooding limit and boiling limit

• Thermosyphons are often several meters long

• prevent permafrost melting along pipelines, roads and train-rails

Heat Pipe Types


• About 120,000 heat pipes were installed along the Trans Alaska Pipeline

Heat Pipe Types


b) Capillary-Driven Heat Pipe:

• Wick provide capillary-driven pumping

• Capillary limit

• Using in almost all laptop computers

• Various commercial and aerospace applications

Heat Pipe Types


c) Annular Heat Pipe:

• Similar to capillary-driven heat pipe

• Main difference in cross section of vapor space

Heat Pipe Types


d) Vapor Chamber

• Capillary-driven planar

• Additional wick blocks

• Can be placed in direct contact with CPU

• Excellent candidate for electronic cooling applications

• Electronic cooling with heat fluxes higher than 50 𝑊 𝑐𝑚2

Heat Pipe Types



• designed to cool machinery by removing heat through a rotating shaft

• rotating heat pipe uses centrifugal forces

• design in tow configuration: a) circular cylinder b) disk type

• a)Cooling rotating parts of electric motors and metal-cutting tools

• b)Cooling turbine components and automobile brakes

Heat Pipe Types



Heat Pipe Types



Heat Pipe Types



• Same as capillary-driven heat pipe

• Difference : a noncondensing gas introduced into the vapor space

• Result: nearly constant evaporator temperature regardless of the heat input

• Using for an isothermal furnace and for electronic cooling

Heat Pipe Types



Heat Pipe Types


g) Loop Heat Pipe

• Compensation chamber

• 2 wick structure in evaporator

• Long thermal transport distance

• Attractive for spacecraft cooling

• Alternative for Thermal control device in scientific heat regulation

• and telecommunication satellites

Heat Pipe Types

g) Loop Heat Pipe


Heat Pipe Types


i) Pulsating Heat Pipe

• Two type: a)looped, b)unlooped

• Self-excited oscillatory motion

• No wick structure

• Weighs less than conventional heat pipe

• Surface tension has a great role in the dynamics of PHP

• Space applications, thermal control of electrical devices

Heat Pipe Types


k) Micro & Miniature Heat Pipes

• 10 μ < Dh <500 μ (micro) , 0.5 mm < Dh < 5 mm (miniature)

• Container from silicon

• Polygonal cross section

• Power Electronics, Electric Train, Air Conditioning(Rood Heating), Aerospace

Heat Pipe Types


k) Micro & Miniature Heat Pipes

Heat Pipe Types


l) Nonconventional Heat Pipes

• Different geometries

• Examples:

• Polygonal: micro Heat Pipe

• Leading edge: future hypersonic aircraft

• Cover the leading edge of the wings and engine nacelles

HPHXs Applications

a) HVAC

b) Waste heat recovery from combustion gases

c) Data center cooling

d) Power plant dry cooling towers

e) Steam condensers

f) Latent thermal energy storage solar power generation

g) CPU cooling in laptop computers


HPHXs Applications


HPHXs Applications


HPHX Types

1. Conventional HPHX

2. PCM-HPHXs

3. Conventional HPHSs

4. PCM-HPHSs

5. Reflux heat exchanger (RHXs)


1. Conventional HPHXs and Applications

Kasra Nakhaee - November 2015

1.1. HVAC systems

1.2. Bakery

1.3. Metal forging

1.4. Automotive

1.5. Data center cooling

1.6. Power plant cooling tower

1.7. Nuclear spent fuel cooling

1.8. Solar water heating

32







• 2.1. General thermal energy storage

• 2.2. Solar thermal power generation

• 2.3. Data center cooling

• 2.4. Automotive


2. PCM-HPHXs and Applications

36

• 3.1. Electronics/CPU cooling using HPHSs

• 3.2. Permafrost stabilization


3. HPHSs and Applications

37

• 4.1. Electronics/CPU cooling using HPHSs

• 4.2. Spacecraft thermal management


4. PCM-HPHSs and Applications

38

• 5.1. Solar water heating

• 5.2. Nuclear rector cooling


5. Reflux Heat Exchangers and Applications

39

References

• Hamidreza Shabgard, Michael J. Allen, Nourouddin Sharifi, Steven P. Benn , Amir Faghri ,Theodore L. Bergman,

2015. Heat pipe heat exchangers and heat sinks: Opportunities, challenges, applications, analysis, and state of

the art. International Journal of Heat and Mass Transfer

• Leonard L. Vasiliev, 2005. Review Heat pipes in modern heat exchangers. Applied Thermal Engineering

• Faghri, Amir, 2012. Review and Advances in Heat Pipe Science and Technology. Journal of Heat Transfer

• Greg F. Naterer, 2008. Heat Exchangers and Heat Pipes. US: Taylor &Francis

• Faghri, Amir, 1995. Heat Pipe Science and Technology. US: Taylor &Francis

• Saunders, E. A. D, 1988. Heat exchangers : selection, design & construction. UK: Longman Scientific & Technical, Wiley

• http://www.1-act.com/rotating-heat-pipes/

• http://www.hexag.org/news/32/sterling.pdf

• http://dtic.mil/dtic/tr/fulltext/u2/a073597.pdf


http://www.sciencedirect.com/science/article/pii/S0017931015005037

http://www.sciencedirect.com/science/article/pii/S1359431103003983

http://heattransfer.asmedigitalcollection.asme.org/article.aspx?articleid=1660651

http://www.tandfonline.com/doi/abs/10.1081/E-EEE-120042339#.Vlio83YrLIU

https://books.google.com/books?hl=en&lr=&id=9QpQAQAAQBAJ&oi=fnd&pg=PR15&ots=MQDIRTASNn&sig=p64dEriCxSNNpNLqUXA4vvSeq6k#v=onepage&q&f=false

https://books.google.com/books?id=b-JSAAAAMAAJ&q=saunders+heat+exchanger&dq=saunders+heat+exchanger&hl=en&sa=X&ved=0ahUKEwiEyvuXp7HJAhVBHA8KHUurAdAQ6AEIHTAA

http://www.1-act.com/rotating-heat-pipes/

http://www.hexag.org/news/32/sterling.pdf

http://dtic.mil/dtic/tr/fulltext/u2/a073597.pdf