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Synthesis
of new refractory oxid materials, radiation furnacing in order
of operating characteristics improvement, thermal, spectral
and optical characteristics definition, extra pure materials
procurement, probation on radiation capability of new technical
bends are realized in conditions of high temperature. The sun
energy magnetic enhancers among with the laser and furnaces
with artificial heat sources are in wide use, their application
is the only decision of mentioned above tasks, when powerful
luminous fluxes of various spectral structure are required.
In these cases, large sized sun energy magnetic enhancers analogous
to Large Solar Furnace (LSF), by 100kWt capacity of SPU "Physics-Sun"
are the most acceptable. |
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Investigations
and synthesis of refractory materials, under an influence of concentrated
solar radiation began in 1976, in the UAS Physical Technical Institute
(PTI) and became the basic scientific direction of the Materials Sciences
Institute (MSI), founded in 1993, on the basis of PTI and LSF laboratories.
The Large Solar Furnace is the complicated
optomechanical complex with automatic executive systems, that consists
of heliostat field and paraboloid concentrator, forming in the concentrator
focal zone (technological tower) a radiation stationary stream of
high density. |
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Furnace is placed in Parkent district, 45 km far from Tashkent,
at Tijen- Shan foothills. Geografical latitude - is 45°20, height
above the sea level - 1050m. On the flat slop of a mountain
62 heliostates of heliostat field placed staggered, that provides
continuous Sun watching the reflecting surface of concentrator
during the day. All 62 heliostates have an identical construction
and dimensions. The heliostat reflecting surface is 7,5 x 6,5
m plane constituent, including 195 mirror elements - facet size
0,5 x 0,5m and 6mm by thickness. The facet reflecting surface
is formed by aluminium vacuum spraying from backside and protected
by the acrylic paint EM AK - 5164. Total quantity of facet -
12090 pcs. , reflecting surface area is 3022,5m |
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heliostat lifting bar is alt - azimuth, electromechanical type of
the driving gear. Kinetic schemes of area and azimuth corner allow
to transfer the heliostat, during watching the Sun, with no more than
1 angle min mistake. Working control of driving gear carries out by
sensing elements signals watching, placed in front of the heliostat
central facet, middle quadratic mistake of the surface do not exceed
30angles sec. All heliostates synchronous control system is foreseen
(placed on one shelf by basic heliostat of the shelf).A mistake of
such direction do not exceed 3 angles min. Moreover, all 62 heliostates,
have possibility of tracing the angle unbalance ab. +25angles min,
in automatic system of temperature adjustment (ASTA), intended for
various kinds of luminous flux allocation providing. |
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Control
can be carried out with the help of automatized control system
of heliostat field. Nowadays heliostates separate shelves is
downloaded to ACSH. ACSH using allows to operate flexibly the
density distribution of luminous fluxes in furnace focal zone
and opens opportunities for astrophysical researches in night
time, using the Large Solar Furnace as unique astrophysical
means..
Luminous flux requested density
forming realizes by taking out from separate heliostat tracing
control under the radiometer control with straight solar radiation
attendant measuring on actinometric stand with the help of ASTA
control or by ACSH program way. |
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concentrator reflecting surface represents rectangle - multi graded
cutting from the paraboloid rotation with 18m focal distance. Midsection
concentrator height is 42,5 m, the lower border is 54 m height from
the earth, the mid section width is 54 m. The total area of reflecting
surface midsection is 1840m?, and the surface is 2060 m?. |
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concentrator installs from 214 blocks in parallelogram form,
4,5 x 2,25 m each side, but with various corners at the top
points, determined by block concentrator. 50 reflecting elements
- rhombus facet installed on each block. The total quantity
of facets is 10700 pcs. Blocks are bounded to the frame by four
nodal points, blocks bounding bends allow to compensate rather
low exactness of the concentrator metal construction frame and
to realize blocks adjustment into the one exact paraboloid surface.
Besides, installation and adjustment of separate facets on the
block realized with the help of special regulating points. Such
kind of system provides the concentrating surface forming with
1angle min exactness. |
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The
facet mirror is glassy, with backside reflecting stratum, formed by
alluminium pellicle rendered by the vacuum spraying method. Mirror
dimensions - 447x447x5. The reflecting surfaces of the facets are
formed by the deformation method and reiterates the curvature of paraboloid
proper zone, on which they are established. Facet has 10 types of
sizes by the form.
Various equipment with necessary engineering
communications for the materials fusion realization and special researches
in the LSF focal zone are placed in technological tower. |
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Blind and rotor - slot hole closing
provides the luminous impulses reception with various forms 1 sec.
duration and more. Automatic system of impulse registration with
the help of photometric measure instrument allows to measure the
characteristic of received impulses and research the examples till
1 m. in diameter. The examples may be exposed to the luminous fluxes'
complex influence, mechanical working load and blowing on.
For regulating works realization
on separate LSF elements adjustments, energetic and spectral measure
characteristic of focal spot, the analyzer of focal spot is used,
automatic system of energy density registration with the help of
radiometer, television measuring system and system of technical
sight.
Watching of straight solar radiation
changing during many years in the location of "Sun" object
shows that quantity of conventional sun days consists of 250-270
days during the year.
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Factor
of mirror reflecting optic elements of the unit, average meaning
is close to 0,7, in the course of time because of the dust content
in the air falls and can decrease till 0,5, that's why preventive
regular works are requested. The exactness of reflecting elements
with the superficial mirror mistakes accounting changes in 30
angle min interval. That kind of system condition allows to
create energetic illumination within the limits of E=3e780-
Wt/sm? , with the step of 3e30 Wt/sm? , at the solar radiation
of 700Wt/m?. The total power of the furnace is about 0,7 MWt
, maximum diameter of focal spot is 1,2m.
The spectral allocation of luminous
field density in the focal area is analogous to allocation of
absolutely black body with the 6000K temperature (atmospheric
sun) with 0,7e1,1mkm downfall in the spectrum area owing to
backside of alluminium spraying on facets and concentrators.
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Nowadays, on the experience basis of LSF
creation and exploitation, complex researches by following directions
of helio technics are carried out::
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working out of optical elements of large sun units;
- an
organization of solar high temperature energetic units planning,
assembling, regulating and introduction them into operation;
- work
out of new methods of mirror-concentrating system (MCS) estimating;
- work
out of new control methods, adjustment of reflecting surfaces of
MCS and concentrator field measuring;
- work
out of new automatic programming methods for heliostat watching
system;
- standartization
of measured characteristics of various mirror refleing elements;
- refining
of parameters of unique probation stand, created on the basis of
"Sun" complex.
A line of researches on technology
synthesis of solar furnace's high temperature oxids was executed
by the scientists of the Institute of materials sciences. More than
160 oxid materials were synthesized, which have unique operation,
physical and chemical characteristics, as small coefficient of thermal
expansion, high resistance and thermal resistance in extreme conditions,
have wide area of application. On the basis of them, were received
:
- multifunction
ceramics (high temperature heaters, thermocouple, transformers,
gas burners);
- constructive
ceramics (the printing circuit board, tubes, ferrules, cutting tools);
- fire
proof ceramics (elements for ceramic engines, restorative surfaces);
- optical,
superconductivity and other types of ceramic materials for electronics,
chemistry and other fields.
Nowadays, after ten years operation,
basic optical operating characteristics of the furnace are appropriate
to planned parameters. LSF plays the important role as unique research
instrument in decision of fundamental and applied problems of science
and technics.
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