which type of design to prefer for heat pipes and get the better perfomance of heat pipe with using nanofluid.

1. Presented by:
KISHOR BALDANIYA
(140320721001 )

2. What is a Heat Pipe?
Working Principle
Types of Heat Pipes
Components of Heat Pipe.
 Experimental procedure
Advantages Of Heat Pipes
Heat Pipe Applications
Review Of Literature And Inference
Conclusion
References.
CONTENTS….

3. A heat pipe heat exchanger is a simple device which is
made use of to transfer heat from one location to another,
using an evaporation-condensation cycle.
Heat pipes are referred to as the "superconductors" of heat
due to their fast transfer capability with low heat loss.
What is a Heat Pipe?

4. Working Principle
• The heat input region of the heat pipe is called evaporator, the
cooling region is called condenser.
• In between the evaporator and condenser regions, there may be
an adiabatic region

5. Types of Heat Pipes
Thermosyphon
Leading edge-
Rotating and revolving-
Cryogenic pumped loop heat pipe
Flat Plate-
Micro heat pipes-
Variable conductance-
Capillary pumped loop heat pipe-

6. • Container
• Working fluid
• Wick or Capillary structure

7. 1.Container
The function of the container is to isolate the working fluid
from the outside environment.
Selection of the container material depends on many
factors. These are as follows:
Compatibility (both with working fluid and external
environment)
Strength to weight ratio
Thermal conductivity
Ease of fabrication, including welding, machineability and
ductility
Porosity
Wettability

8. Container materials
Of the many materials available for the container, three are by
far the most common in use—name copper, aluminum, and
stainless steel.
Copper is eminently satisfactory for heat pipes
operating between 0–200◦C in applications such as electronics
cooling.
While commercially pure copper tube is suitable, the oxygen-
free high conductivity type is preferable.
Like aluminum and stainless steel, the material is readily
available and can be obtained in a wide variety of diameters and
wall thicknesses in its tubular form.

9. The prime requirements are:
1.compatibility with wick and wall material
2.Good thermal stability
3.wettability of wick and wall materials
4.vapor pressure not too high or low over the operating
temperature range
5.high latent heat
6.high thermal conductivity
7.low liquid and vapor viscosities
8.high surface tension
9.acceptable freezing or pour point

10. Examples of Working Fluid
Medium
Melting Point
(°C)
Boiling Point at
Atm. Pressure
(°C)
Useful Range
(°C)
Helium -271 -261 -271 to -269
Nitrogen -210 -196 -203 to -160
Ammonia -78 -33 -60 to 100
Acetone -95 57 0 to 120
Methanol -98 64 10 to 130
Flutec PP2 -50 76 10 to 160
Ethanol -112 78 0 to 130
Water 0 100 30 to 200
Toluene -95 110 50 to 200
Mercury -39 361 250 to 650
Sodium 98 892 600 to 1200
Lithium 179 1340 1000 to 1800
Silver 960 2212 1800 to 2300

11. Using Nanofluids as a Working Fluid
❖ Nanofluids have significantly higher thermal conductivities
compared to traditional fluids
❖ Although better performance, imposing nanoparticles increases
density and viscosity; hinders the performance of the heat pipe

12. Nanoparticle Selection
Al2O3
❖ Design for:
❖ High thermal conductivity.
❖ Optimal nanofluid mass concentration.
❖ Small particle size.
❖ Aluminum Oxide is a workable fluid as
long as:
❖ Range of specific heat flux at the desired
temperature range.
❖ Compatibility with the pipe and the wick.

13. 1. It is a porous structure made of materials like
steel,alumunium, nickel or copper in various ranges of pore
sizes.
2. The prime purpose of the wick is to generate capillary
pressure to transport the working fluid from the condenser to
the evaporator.
3. It must also be able to distribute the liquid around the
evaporator section to any area where heat is likely to be
received by the heat pipe.

14. 4. Wicks are fabricated using metal foams, and more particularly
felts, the latter being more frequently used. By varying the
pressure on the felt during assembly, various pore sizes can be
produce.
5. The maximum capillary head generated by a wick increases with
decrease in pore size.
6. The wick permeability increases with increasing pore size.
7. Another feature of the wick, which must be optimized, is its
thickness. The heat transport capability of the heat pipe is raised
by increasing the wick thickness.
8. Other necessary properties of the wick are compatibility with the
working fluid and wettability.

16. Wick Design
Two main types of wicks: homogeneous and composite.
1.Homogeneous- made from one type of material or
machining technique. Tend to have either high capillary
pressure and low permeability or the other way around.
Simple to design, manufacture, and install .
2.Composite- made of a combination of several types or
porosities of materials and/or configurations. Capillary
pumping and axial fluid transport are handled
independently . Tend to have a higher capillary limit than
homogeneous wicks but cost more.

18. Three properties effect wick design
1. High pumping pressure- a small capillary pore radius
(channels through which the liquid travels in the
wick) results in a large pumping (capillary) pressure.
2. Permeability - large pore radius results in low liquid
pressure drops and low flow resistance. Design
choice should be made that balances large capillary
pressure with low liquid pressure drop. Composite
wicks tend to find a compromise between the two.
3. Thermal conductivity - a large value will result in a
small temperature difference for high heat fluxes.

19. Ideal Thermodynamic Cycle

20. 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.
(Faghiri, 1995)

21. Experimental procedure
❖ The experiment setup consists of resistance heater, watt meter, and variable
voltage transformer.
❖ Data acquisition part consists of temperature data logger and PC to record the
thermocouple readings at different positions of the heat pipe.
Heat Pipe setupFull experiment setup

22. •The experimental system was composed of a cooling system, the test section, a power
supply and measurement system, and a data acquisition system.
• A PC was used to monitor and process the experimental data. The cooling system
included a constant-temperature thermal reservoir and a cooling chamber.
• The condenser section of the heat pipe was inserted horizontally into the cooling
chamber.
• The coolant circulated through the cooling chamber, where heat was removed from
the condenser section by forced convection, and then to a constant-temperature
reservoir.
•The constant-temperature reservoir was set to the required temperature and held at a
constant temperature through the tests.
•The temperature variation of the cooling fluid was held to within 40°C.

23. Analysis of Experiment
Although heat pipes are very efficient heat transfer devices, they are subject to a
number of heat transfer limitations.
There are various parameters that put limitations and constraints on the steady
and transient operation of heat pipes.
These limitations determine the maximum heat transfer rate a particular heat pipe
can achieve under certain working conditions.
 For high heat flux heat pipes operating in a low to moderate temperature range,
the capillary and boiling limits are commonly the dominant factors that govern
the operation of heat pipes.

24. Capillary Limit
For a given capillary wick structure and working fluid combination, the pumping
ability of the capillary structure to provide the circulation for a given working
medium is limited.
 This limit is usually called the capillary or hydrodynamic limit. In order to
maintain the continuity of the interfacial evaporation, the capillary pressure head
must be greater than or equal to the sum of pressure losses along the vapor-liquid
path.
 The pressure balance can be expressed as
gcevlcap PPPPPP ∆+++∆+∆≥∆ δδ ,,max,

25. Boiling Limit
Nucleation within the capillary wick is undesirable for wicked heat pipe
operation since the bubbles can obstruct the liquid circulation and cause hot
spots on the heated wall.
 If the boiling is severe it dries out the pipe wall, which is defined as the boiling
limit.
However, under a moderate heat flux, low intensity stable boiling is possible
without causing dry out.
It should be noted that the boiling limitation is a radial heat flux limitation as
compared to an axial heat flux limitation for the other heat pipe limits.

26. S.No Title Author/Journal/
Year
Inference
(1)
Heat Transfer Performance in
Heat Pipe Using Al2O3 –DI
Water Nanofluid.
R. Reji Kumar,
K. Sridhar, M.
Narasimha /
2014
Heat pipes are two-phase heat
transfer devices with high effective
thermal conductivity. This study
presents the improvement of
thermal performance of heat pipe
using Al2O3 nanofluid. The
nanofluids kept in the suspension of
conventional fluids have the
potential of superior heat transfer
capability compared to the
conventional fluids due to their
improved thermal conductivity. The
performance of the heat pipe
greatly depends on the filling ratio
of the working fluid.
(2)
A Study On The Heat Transfer
of Nanofluids in Pipes
Koh Kai Liang
Peter /2014
This paper aims to investigate
whether the use of nanofluids as a
working fluid, as opposed to using
water/oil, will reduce the pipe
dimensions in an industrial set up.
Review of Literature and Inference…

27. S.No Title Author/Journal
/Year
Inference
(3)
Experimental Investigation
of Convective Heat Transfer
Coefficient of CNTs
Nanofluid under Constant
Heat Flux. .
F. Rashidi, N.
Mosavari
Nezamabad /
2013
This study is concerned with the heat
transfer behavior of aqueous suspension
of multi-walled carbon nanotubes
flowing through a horizontal tube under
constant heat flux. We measured heat
transfer coefficient of CNTs nanofluid in
laminar flow regime.
(4)
Performance Analysis of
Heat Pipe Using Copper
Nanofluid with Aqueous
Solution of n-Butanol.
Senthilkumar
R,
Vaidyanathan
S, Sivaraman
B/2011
The nanofluids kept in the suspension of
conventional fluids have the potential of
superior heat transfer capability than the
conventional fluids due to their
improved thermal conductivity. In this
work, the copper nanofluid which has a
40 nm size with a concentration of 100
mg/lit is kept in the suspension of the de-
ionized (DI) water and an aqueous
solution of n-Butanol and these fluids are
used as a working medium in the heat
Review of Literature and Inference contd…

28. S.No Title Author/Jour
nal/Year
Inference
(5)
Experimental investigation
of silver nano-fluid on heat
pipe thermal performance.
Shung-Wen
Kang, Wei-
Chiang Wei,
Sheng-Hong
Tsai, Shih-
Yu Yang /
2009
Nano-fluid is employed as the working
medium for a conventional 211 µm wide
217 µm deep grooved circular heat pipe.
The nanofluid used in this study is an
aqueous solution of 35 nm diameter
silver nano-particles. The experiment
was performed to measure the
temperature distribution and to compare
the heat pipe thermal resistance using
nano-fluid and DI-water. The tested
nano-particle concentrations ranged
from 1 mg/l to 100 mg/l.
(6)
Experimental study of
silver nanofluid
On flat heat pipe thermal
performance
Yu-Tang
Chen/2010
This study utilizes silver nano-fluid
filled flat heat pipe. It is aimed at effect
of various concentrations on flat heat
pipe thermal performance by air-cooling
testing equipment. The particles used in
these experiments were silver particles
35 nm in size. The base working fluid
Review of Literature and Inference…

29. Advantages Of Heat Pipes
May reduce or eliminate the need fir reheat,
Allow cost effective manner to accommodate new
ventilation standards,
Requires no mechanical or electrical input,
Are virtually maintenance free,
Provide lower operating costs,
Last a very long time,
Readily adaptable to new installations and retrofiting
existing A/C units and
Are environmentally safe.

30. Heat Pipe Applications
Electronics cooling- small high performance components
cause high heat fluxes and high heat dissipation demands.
Used to cool transistors and high density semiconductors.
Aerospace- cool satellite solar array, as well as shuttle
leading edge during reentry.
Heat exchangers- power industries use heat pipe heat
exchangers as air heaters on boilers.
Other applications- production tools, medicine and
human body temperature control, engines and automotive
industry.

31. Conclusion
Heat transfer device that dissipates heat by the use of a
working fluid, wick, evaporator, and condenser
Used in space applications and small technological
devices
Nanofluids increase thermal conductivity of working
fluid, enhances thermal performance

32. REFERENCES
Andrews, J; Akbarzadeh, A; Sauciue, I.: Heat Pipe
Technology, Pergammon, 1997.
Dunn, P.D.; Reay, D.A.: Heat Pipes, Pergammon, 1994.
www.heatpipe.com.
www.cheresources.com.
www.indek.com
www.wikipedia.org

33. THANK YOU