The document discusses heat pipes, including their types, working, components, and experimental setup used. It describes how heat pipes use evaporation and condensation to transfer heat from one location to another with low heat loss. The experiments tested a copper heat pipe with different working fluids and fill ratios. Results showed the heat pipe performed best with 100% fill ratio, demonstrating minimum temperature difference between the evaporator and condenser sections.

1. GUIDE: SUBMITTED BY,
NIMU MARY HARISANKAR S
ASST. PROF S7 ME
MECHANICAL DEPT. ROLL NO. 30
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2.  INTRODUCTION
 TYPES
 WORKING
 COMPONENTS
 EXPERIMENTAL SETUP
 PROCEDURE
 RESULTS AND DISCUSSIONS
 CONCLUSION
 REFERENCES
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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.
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5.  Thermosyphon
 Leading edge-
 Rotating and revolving-
 Cryogenic pumped loop heat pipe
 Flat Plate-
 Micro heat pipes-
 Variable conductance-
 Capillary pumped loop heat pipe-
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• 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

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Container
Wick or Capillary structure
 Working fluid

8. 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
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9.  It is a porous structure made of materials like
steel,aluminium, nickel or copper in various ranges
of pore sizes.
 The prime purpose of the wick is to generate
capillary pressure to transport the working fluid
from the condenser to the evaporator.
 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.
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10. The prime requirements are:
 compatibility with wick and wall material .
 Good thermal stability.
 vapor pressure not too high or low over the
operating temperature range .
 high latent heat .
 high thermal conductivity .
 low liquid and vapor viscosities.
 high surface tension.
 acceptable freezing or pour point.
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11. • The heat pipe is fabricated using a copper tube of 150
mm length and 5 mm inner dia and 8 mm outer
diameter
• Ni-Cr wire was used to make a heater of 230V, 50W
capacity and heater was used for providing the required
heat source at the evaporator.
• Variac and multimeter were provided to control and
measure the power input respectively.
• Thermocouple wires were used as temperature sensors
• A simple 8- channel digital temperature indicator is
used to measure the temperature
• Five copper fins of length 50mm, width 15 mm, and
thickness 0.5mm were brazed on the condenser end.
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13.  Experiments were conducted with dry
run(without any working fluid in the tube) and
wet run(with acetone inside).
 The transient tests were conducted on the heat
pipe, in which heater was put on and the
temperature rise was observed at regular
intervals till the steady state was achieved. After
achievement of
 steady state the temperatures at the six points
were noted by changing the positions of the
selector switch.
 This experiment was repeated for different heat
inputs, different fill ratios
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 Axial temperature profiles:
 The axial temperature distribution along the heat pipe for
dry run and wet run (with 55% fill ratios) are shown
 For dry run the slope of axial temperature distribution
increases with heat input and shows larger temperature
differences across the condenser and evaporator
section,for wet run slope reduces

15. Variations of Heat Transfer Co-Efficients and
Thermal Resistances with Varying Heat Loads:
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17.  it is clear that at higher fill ratios of acetone
a miniature heat pipe will perform good
 as it shows higher values heat transfer co-
efficients and
 lower values of thermal resistances at higher
fill ratios.
 For lower fill ratios the performance of
miniature heat pipe degrades
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18.  The steady state temperature increases with
increased heat loads. Slope of axial temperature
distribution in dry run increases with the heat
input, on the other hand the wet run shows an
averaged constant temperature slopes.
 The operating heat pipe with wet run has lesser
overall thermal resistance when compared to dry
run
 The overall heat transfer coefficient of heat pipe
increases with increase in heat input, in the range
of inputs
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19.  The temperature difference across
evaporator and condenser continues to drop
down with an increase in the fill ratio
 100% fill ratio of evaporator volume shows
the best result with minimum temperature
difference across the evaporator and
condenser.
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20.  PERFORMANCE OF HEAT PIPE FOR DIFFERENT WORKING FLUIDS
AND FILL RATIOS,A. K. Mozumder,*, A. F. Akon, M. S. H.
Chowdhury and S. C. Banik, Journal of Mechanical Engineering,
Vol. ME 41, No. 2, December 2010Transaction of the Mech. Eng.
Div., The Institution of Engineers, Bangladesh
 Recent developments in heat pipe technology and
applications: a review,Saffa Riffat (corresponding author) and
Xiaoli Ma Institute of Sustainable Energy Technology, School of
the Built Environment, University of Nottingham, Nottingham,
NG7 2RD, UK, International Journal of Low Carbon
Technologies,august 2016
 Heat Pipe for Aerospace Applications—An Overview ,K. N.
Shukla,PRERANA CGHS Ltd., Gurgaon, IndiaJournal of Electronics
Cooling and Thermal Control, 2015
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