Solar absorbers

Randich, E., and Allred, D., CVD ZrB2 as a Selective Solar Absorber, Thin Solid Films, 83 394-398 (1981)... 

Metal deposition processes, early,. 9 760-761. See also Electroless deposition Metal deposition systems, in compound semiconductor processing, 22 188-189 Metal-dielectric composite-metal tandem solar absorbing surface, 23 11 Metal dithionates, 23 677-678 uses for, 23 677-678... 

Multilayer-metal tandem solar absorbing surface, 23 11... 

Dyes (commercial samples) Ti02-Solar -Absorbance, -TOC +[C1"[ Wang (2000)... 

Reactive red 11 (textile dye) Ti02-solar -Absorbance Neppolian et al. (1999)... 

In general, metal oxides are very common inorganic commodities, widely applied, and display an assortment of unique chemical and physical properties. They are accessible by different techniques including chemical vapor deposition and sol-gel methods. Their technological application extends from super- and semiconducting materials to electrochromic devices, optical filters, protective coatings and solar absorbers ... 

The variations of the spectral emissivity of two surfaces are a.s given in Fig. P12-46, Determine the average emissivity of each surface at T = 3000 K. Also, determine the average absorptivity and reflectivity of each surface for radiation coming ftom a source at 3000 K. Which surface is more suitable to serve as a solar absorber ... 

Improved selectivity of potash recovery may be obtained by high ammonia concentrations in water, but this has not been commercially adopted. Solution mining of potash has matured from the pioneering work of Kalium Chemicals at Belle Plaine, Saskatchewan [39], to encourage adoption by at least two operations formerly based on conventional mining [40]. These operations are sited to use solar evaporation for potash recovery. One uses 162 hectares (1.62 km ) of PVC-lined evaporation ponds to produce 236,000 tonnes of potassium chloride per year [29]. Experiments with solar absorbing dyes may lead to further increases in production. 

While the importance of cobalt-based pigments in ceramics is well established, it has also been shown that thin films of C03O4 provide an effective coating for solar collectors that operate at high temperatures. The properties of black C03O4 that make it suitable for this application are its high solar absorbance and low IR emittance. 

Cobalt(ii) oxide, CoO, has been used in solar absorbers [66]. It can be prepared by the CVD of cobalt(ii) acetylacetonate dihydrate (Co(acac)2 2 H2O acac 6) at temperatures between 150 °C and 400 °C [67]. Cobalt(II) acetate can be converted into CoO at temperatures above 300°C [66]. The decomposition yields a polycrystalline material. 

Zirconium and hafnium diboride have been studied less extensively. Zirconium diboride potentially is useful as a coating for solar absorbers [242]. These compositions can be prepared either by hydrogen co-reduction of the metal and boron halides [242], or by the decomposition of the metal tetrakis(tetrahydroborates) M(BH4)4 [241]. 

Selective Absorber - A solar absorber surface that has high absorbtance at wavelengths corresponding to that of the solar spectrum and low emittance in the infrared range. 

Selective Surface Coating - A material with high absorbtance and low emittance properties applied to or on solar absorber surfaces. 

FIGURE 24.6 Relative solar absorbance of several grains. (From Arinze, E.A. et al.. Solar Energy Absorption Properties of Some Agricultural Products, ASAE Paper No. 79-3071, American Society of Agricnltural Engineers, St. Joseph, MI, 1979. With permission.)... 

The formation of periodical structures in the nanoscale is a busy field in the physics of materials. Submicrometer stractured materials have, and are expected to have, various apphcations [1 ], like optical filters and gratings, an-tireflective surface coatings, high density data storage, selective solar absorbers, microelectronics, optical switches, waveguides with low lost, chemical and biochemical sensors and resonant cavities for small lasers. 

Thornton BS. (1975) Limit of the moth s eye principle and other impedance-matching corrugations for solar-absorber design. / SocAm 65 267—270. 

CZTS is composed of abundant and non-toxic elements and has a 1.45-1.51 eV band gap with a high optical absorption coefficient (> 104 cm ), which makes it suitable for solar cell absorber layers. CZTS also shows promising thermoelectric properties, with ZT values of up to 0.36 at 700 K. Control of the materials composition has been shown to be fundamental for optimization of its functional properties. Solution processed CZTS absorber layers have provided photovoltaic efficiencies much higher than those obtained by vacuum-deposition techniques. This may be attributed to the better control of the composition and crystal-phase homogeneity by solution processing. Therefore, solution based routes for the preparation of solar absorber materials and solar cells are moving more and more into focus of scientific and industrial research. 

Abstract. Usual plate solar collectors, based on a metal absorber (Cu, Al) selectively coated are technologically very sophisticated, expensive to produce and they are great consumer of fossil raw material. Polymeric materials are considered as a promising alternative for many interesting properties easy moldability, corrosion resistance, they also offer a significant cost-reduction for solar thermal collectors, and a mass production may thus benefit to a broader utilization of solar energy. Most drawbacks of polymers are their low thermal properties essentially thermal conductivity coefficient may strongly affect the solar absorber efficiency and deteriorate the collector performance. 

In the literature, several polymers have been used as absorber in flat-plate collectors. P. T. Tsilingiriss reported upon the use of the groups of polyolefin and EDPM, to overcome the undesirable effects of the poor thermal conductivity, he had exploited the design of the solar collector [4]. Polycarbonate selectively coated has been used as solar absorber plate double walled, by A. I. Kudish et al [5]. In another case, K. Sopian had developed a solar collector system using black fibreglass reinforced polyester (GFRP) [6]. 

In this study, the main goal was the elaboration of a thermal conductive CPC (Conductive Polymer Composite) that will be used in thermal solar panel. In fact, the conductive polymer composite was obtained by blending bio-polymer matrix by different percentages of fillers (eGR/CNT). Effect of fillers percentage on thermal conductivity, solar absorbance and total emittance was investigated. 

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