الفهرس 
LITERATURE REVIEW
Temperature DistributionOnly 14 pages are availabe for public view
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Abstract
Heat pipes and thermosyphons are devices capable of transporting
high heat rates with isothermal operation. and cover a large active area
• in the space and terrestrial applications. In this research, the liquid
metal thermosyphon is utilized for the first time at relatively moderate
operating temperatures.
The study of the behaviour and mechanism of evaporation and
condensation processes is very important for the design purpose. The
steady-state operation of an inclined mercury/stainless steel two-phase
closed thermo syphon is investigated experimentally. The study aims
basically to investigate the effect of varying the heating rate (heat flux),
evaporator charging quantity (liquid fill ratio). operating temperature
and the inclination angle. on thermo syphon operation.
A thermosyphon with 21.6 mm inside diameter.
25.4 mm outside diameter and 90 em long was used. Both the
evaporator and condenser lengths are 32 cm , whilst the adiabatic
section has 26 em length. The evaporator section is uniformly heated
while the condenser section is convectively cooled. Some special
features are introduced in the design of the present thermosyphon.
Namely these features include -: a vapour temperature probe,
distributing blocks for uniform heating I cooling block thermal resistor I
conducting copper powder layer in the evaporator and condenser sectionto minimize the thermal resistance to heat flow, bajJle structure in the
cooling jacket and geysering decay mechanism.
Experiments on the mercury / stainless steel thermosyphon are
performed in the range of: 4.87-22.13 kW/m2 of radial heat flux,
0.5-1.0 of liquid fill ratio, ~52-267°C operating temperature and 0-70°
inclination angle. An analysis is performed for the boiling liquid pool,
liquid film evaporation and condensation heat transfer coefficients in the
vertical position (9 = 0°). In addition, an analysis is performed for the
equivalent overall heat transfer coefficient of inclined thermosyphon. In
addition, the axial wall temperature distribution of the interior surface
of thennosyphon is considered.
Results of the experimental data showed that :
(a) The axial wall temperature distribution is only uniform in the
adiabatic and condenser sections. While the wall temperature
decreases with the axial distance in the evaporation section owing
to the hydrostatic head of mercury pool.
(b) The liquid fill ratio has generally small effect on the heat transfer
coefficients in the liquid pool , liquid film and condensation regions.
While these coefficients are greatly dependent on the radial heat flux.
(c) The equivalent overall heat transfer coefficient of thennosyphon
is affected to a great extent by the axial heat flux and the operating
temperature. But, it is slightly affected by the liquid fill ratio.
(d) The effective thermal conductivity of thermosyphon is very
high, and reached about 68 and 64 times higher than the copper and
silver thermal conductivitie