1. Introduction

One of the promising directions in the use of solar energy is materials science. As is known, high-temperature heating by solar radiation has certain advantages, e.g., the absence of pollution from synthesized materials, instantaneous heating, the possibility to control the heating and cooling rate, a wide range of solar radiation, etc. At present, high-temperature solar technologies are widely applied in many areas of science and engineering. In this respect, concentrated solar energy is an important component among the available material synthesis methods with a set of specified properties [1–8].

The important characteristics of the technological processes are the capacity, maximum and average energy densities, uniformity of the energy density distribution, focal spot size, character of the energy density distribution and its change in time, duration of the process, start and stop mode rate, etc.

A characteristic drawback of solar concentrators is variability of the characteristics of the focal spot with time. This is related, on the one hand, with the temporary change in the direct solar radiation value, and on the other hand, with the condition of the optical and mechanical elements of solar furnaces, i.e., the adjustment

condition of the mirrors, angular inaccuracies of the light-reflecting mirrors, reflection coefficient of the mirrors, condition of the solar sensors, etc.

The Materials Science Institute of the Academy of Sciences of the Republic of Uzbekistan operates a large solar furnace of 1000 kW thermal power (LSF). It is a composite optical and mechanical complex with automatic control systems, comprising the heliostat field (62 heliostats), paraboloidal concentrator (with 1906 m2 midship section area-projection of the surface of the concentrator on the plane), and technological tower. Highly concentrated solar radiation, with energy density up to 700 W/cm2 , may be nowadays created in the focal region of the LSF, located in the technological tower. A set of specialized testing facilities are developed at the LSF, having not analogues in terms of a number of parameters either in home or foreign practice. Note that the abbreviation BSF (Big Solar Furnace) is often used instead of the LSF.

panes (facets). The movement of this installation is guided by electronic controls operated by reflected rays. The accuracy of the control is 1 min of arc, but due to dispersion on the flat glass, 5 min of arc are obtained on the reflected rays. A solar beam of constant energy is directly horizontally southward to a paraboloid reflector of 2000 m<sup>2</sup> intercepted area. This paraboloid contains 9500 single glass panes, bent by mechanical constraint and adjusted to reflect maximum radiation to the focal

Thousand kW High-Temperature Solar Furnace in Parkent (Uzbekistan) – Energetical…

Technological capabilities of the furnace are described in the works [2–5].

The LSF as noted above represents a complex optomechanical aggregate with automatic control systems consisting of a heliostat field and paraboloid concentrator, which form a high-density radiation flux in the focal zone of the concentrator. The furnace is located 50 km from Tashkent, in the Parkent District. The geographical location is 41.32°N, 69.74°E; its altitude above sea level is 1050 m.

The LSF heliostat field is formed by 62 heliostats located on the smooth slope of a mountain (slope 13°) in a checkerboard pattern arranged on 8 terraces. All 62 heliostats of the LSF have a similar structure and dimension. The reflecting surface of the heliostat with dimensions of 7.5 6.5 m is flat and composite and consists of

plane, situated 18 m from the apex of the parabola [3, 4, 11].

195 facets with dimensions of 0.5 0.5 m and a thickness of 6 mm.

2. Main technical characteristics of the LSF

DOI: http://dx.doi.org/10.5772/intechopen.83411

Figure 2.

113

(a) Overview diagram of LSF and (b) general view of the LSF.

The LSF was put into operation as an experimental-industrial one, in the summer of 1987 [9, 10].

During Soviet times this unique solar furnace was the leading facility of militaryindustrial complex for testing of different materials and equipment to the action of concentrated solar radiation and for development of advanced ceramic materials for high-tech industry.

In connection with the change of research direction (from military to peaceful), the fields of technology of engineering ceramics, fireproof materials of wide range of applications, particularly for metallurgy, oil and gas complex, power engineering, machine building, and chemical industries became the major directions of use of LSF.

Scientists in Uzbekistan have achieved significant results in high-temperature solar technologies. More than 150 compositions of various oxide materials having unique properties and serving as the basis for functional, structural, and highrefractory ceramics have been developed and synthesized at the LSF, and their thermophysical and other characteristics have been studied. The LSF is a unique instrument for field studies of high-temperature processes, i.e., on the synthesis and heat treatment of materials and study of their properties.

Note that such a furnace was previously commissioned in Odeillo, France. This 1000 kW solar furnace was completed in 1970 (Figure 1). The furnace contains 63 orientated mirrors (heliostats), each of 45 m2 surface, with 180 single mirror

Figure 1. General view of the France furnace.

Thousand kW High-Temperature Solar Furnace in Parkent (Uzbekistan) – Energetical… DOI: http://dx.doi.org/10.5772/intechopen.83411

panes (facets). The movement of this installation is guided by electronic controls operated by reflected rays. The accuracy of the control is 1 min of arc, but due to dispersion on the flat glass, 5 min of arc are obtained on the reflected rays. A solar beam of constant energy is directly horizontally southward to a paraboloid reflector of 2000 m<sup>2</sup> intercepted area. This paraboloid contains 9500 single glass panes, bent by mechanical constraint and adjusted to reflect maximum radiation to the focal plane, situated 18 m from the apex of the parabola [3, 4, 11].

Technological capabilities of the furnace are described in the works [2–5].
