Parabolic trough concentrators

The photovoltaic static parabolic trough concentrator module has been developed in the All-Russian Research Institute for Electrification of Agriculture (VIESH) for stand-alone and large-scale applications [9]. 

For production cost estimation of PV parabolic trough concentrator module several assumptions were made ... 

Compound parabolic collectors (CPCs) belong to the most promising photocatalytic solar reactors which combine the advantages of parabolic trough concentrator and non-concentrating system [178]. CPCs are low-concentration static collectors with reflective surface and can be designed for any given reactor shape (see Fig. 7.3a) [182]. The CPC reflectors are usually made from polished aluminum... 

A 354 mW thermal solar plant at Kramer Junction in the Harper Valley in California that has been in operation since 1985 (courtesy of NREL/DOE). (Top) This is one of nine solar electric energy-generating plants at Kramer Junction, California and it uses parabolic troughs to collect the Sun s energy. (Courtesy of National Recoverable Energy Laboratory-NREL/DOE.) (Bottom) In the receiver tubes, hot oil transports the concentrated solar heat to steam boilers, which drive the turbine generators. 

The first concentrating trough-type solar power plant in the United States was built in 1988. It is the 1 mW Saguaro plant located north of Tucson, Arizona, and was built for Arizona Public Service (APS). It covers 1 km2 and has parabolic trough-shaped mirrors. 

U.S. and one industrial waste water treatment in Spain. Engineering scale field experiments have been conducted by the National Renewable Energy Laboratory (NREL) at the Lawrence Livermore National Laboratory (LLNL) treating ground water contaminated with trichloroethylene (TCE) [253]. This field system consisted of 158 m2 of parabolic trough reactors and used De-gussa P25 particles (0.1%) as the photocatalyst in a slurry flow configuration. With this relatively low titanium dioxide content the TCE concentration was reduced from 200 ppb to less than 5 ppb. 

Concentrating collectors are only able to use a limited fraction of fhe diffuse solar radiation. This utilizable fraction can be estimated as the inverse of the concentration ratio of fhe collecfor (1/Cr) (Rabl, 1985). Because of this, parabolic trough photocatalytic reactors, which have a concentration ratio around 15 or higher, miss practically all diffuse radiation. This amounts to losing around half of fhe available UV solar irradiance. 

Figure 8 Reaction rate optical factor as a function of catalyst concentration for a parabolic trough solar photocatalytic reactor. Adapted from Arancibia-Bulnes and Cuevas 2004, with permission from Elsevier.

Figure 19 Distribution of spectral volumetric absorbed power inside a tubular reactor illuminated by a 90° rim angle parabolic trough solar concentrator. Wavelength 325 nm and catalyst concentration 0.15 gL (Reprinted from Arancibia-Bulnes and Cuevas, 2004, with permission from Elsevier).

Three main types of concentrating collectors have evolved for use in solar thermal systems low concentration parabolic troughs, high concentration parabolic dishes, and central receivers (Fig. 3). Higher concentration produces higher temperatures in a working fluid and makes electrical generation more efficient. 

Heat from the sun can be concentrated by parabolic troughs, parabolic dishes, or by mirrors to produce steam for generating electrical power. These can be used to heat a fluid at the focal point of the parabola from which the fluid is then pumped to the steam generator. The heat can also be... 

The photothermal reactor was tested in July, 1997 for toree weeks on paint boofli emissions using natural sunlight A representative data set for July 22, 1997 is shown in Figure 22.4.9 in which the total VOC concentration for the inlet and the outlet of the parabolic trough, photothermal reactor is plotted against illumination time. The solvent stream, whieh varied with time, generally eon-tained about 140 ppmv of toluene, methyl ethyl ketone, methyl isobutyl ketone, xylenes, butyl aeetate and ethyl benzene. The oper-... 

Figure 22.4.9. VOC concentration from paint solvents as a fiinction of illumination time during photocatalytic treatment with a concentrating, parabolic trough, solar photoreactor.

The aim of the solar thermal collector development is to improve and optimize them for the temperature level from 80 °C to 250 °C. There are different approaches like double-glazed flat plate collectors with anti-reflection coated glazing, stationary compound parabolic concentrator (CPC) collectors, evacuated tube collectors, vacuum flat plate collectors, small parabolic trough collectors, linear concentrating Fresnel collectors and a concentrating collector with a stationary reflector. 

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