Dish concentrator

Fresnel lens-type PV concentrators have operated at 26% efficiency (Amonix, Inc.). The efficiency of concentrating PV designs can reach 25-30%, and DSG thermal systems can also reach 30%. Similarly, the efficiency of dish concentrators using Stirling heat engines is also about 30%. Table 1.42 provides a summary of solar collector costs, efficiencies, and suppliers. 

This approach first proposed by Solar Systems in Australia employs a dish concentrator that reflects sunlight onto a focal point (see Fig. 6). At the focal point is a spectral splitter (heat mirror) that reflects infrared solar radiation and transmits the visible sunlight to high-efficiency solar cells behind the spectral sphtter. Figure 7 schematically shows the transmission across the solar spectrum wavelengths. 

The largest cost for the hybrid solar concentrator system will be for the dish concentrator and PV receiver, shown in Fig. 6. Algora recently completed an extensive cost analysis based on previously collected data for CPV systems.7 Many of the... 

Applications of the techniques of nonimaging optics in the design of solar thermal concentrators has resulted in significant performance improvements in conventional short focal length dish concentrators, dramatic changes in the approach to solar furnace design, and the establishment of new solar flux concentration records in air and in refractive media. These accomplishments in just over ten... 

It is frequently necessary to concentrate a filtrate in order to obtain a further crop of crystals, or it may be necessary to concentrate a solution to a smaller volume. If the solvent is water and the substance is not volatile in steam, simple evaporation on a large dish on a steam or water... 

To prepare crystalline monoperphthalic acid, place the thoroughly dry ethereal solution (4) in a distilling flask equipped with a capillary tube connected with a calcium chloride or cotton wool drying tube, and attach the flask to a water pump. Evaporate the ether without the application of heat (ice will form on the flask) to a thin syrup (about 150 ml.). Transfer the syrup to an evaporating dish, rinse the flask with a little anhydrous ether, and add the rinsings to the syrup. Evaporate the remainder of the ether in a vacuum desiccator over concentrated sulphuric acid about 30 g. of monoperphthalic acid, m.p. 110° (decomp.), is obtained. 

Nicotinamide. Place 50 g. of pure ethyl nicotinate (Section V,23) in a 350 ml. bolt-head flask and add 75 ml. of concentrated aqueous ammonia saturated at 0°. Keep the flask loosely stoppered for 18 hours, after w)iich time the lower layer generally dissolves on shaking. Saturate the solution with ammonia and allow it to stand for a further 4 hours. Repeat the saturation with ammonia crystals of the amide commence to appear in the solution. Evaporate to drjmess in a dish on the steam bath and dry at 120°. The yield of nicotinamide, m.p. 130°, is usuallj quantitative. 

Method 2. Ethyl p-nitrobenzoate. Place 21 g. of p-nitrobenzoic acid (Section IV,154), 11-5 g. of absolute ethyl alcohol, 3 8 g. of concentrated sulphuric acid, and 30 ml. of sodium-dried A.R. benzene in a 250 ml. round-bottomed flask, fit a reflux condenser, and heat the mixture under reflux for 16 hours. Add 50 ml. of ether to the cold reaction mixture, wash the extract successively with sodium bicarbonate soiution and water, dry with anhydrous magnesium sulphate or calcium chloride, and distil off the solvent on a water bath. Remove the last traces of benzene either by heating in an open evaporating dish on a water bath or in a bath at 100-110°. The residual ethyl p-nitrobenzoate (21 g.) solidifies completely on cooling and melts at 56°. 

Oxidation of galactose (or a galactose-containing sugar) to mucic acid. Dissolve 1 g. of galactose or lactose in a mixture of 10 ml. of water and 5 ml. of concentrated nitric acid contained in a small evaporating dish, and evaporate the solution to dryness on a water bath. Stir the cold residue with 10 ml. of cold water, filter off the mucic acid, wash it with cold water, dry and determine the m.p. (212-213° with decomposition). 

Transfer the filtrate to a ceramic evaporating dish and heat on a water bath until a crystalline scum forms on the top. Cool the dish quickly then filter the mess on the vacuum Buchner to yield 96g of Methylamine Hydrochloride. Concentrate the filtrate once again to obtain a second crop of crystals, -IQg. Concentrate the filtrate a third time as far as possible using the water bath, then store the dish in a vacuum dessicator loaded with Sodium Hydroxide in the bottom for 24 hours. Add Chloroform to the residue left in the crucible to dissolve out Dimethylamine Hydrochloride (distill off the Chloroform to recover - good stuff) then filter on the venerable old vacuum Buchner funnel to yield an additional 20g of Methylamine Hydrochloride, washing the crystals in the funnel with a small poiiion of Chloroform ( 10mL). 

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

When both solids and gases pass through the distributor, such as in catalytic-cracldng units, a number of variations are or have been used, such as concentric rings in the same plane, with the annuli open (Fig. 17-9a) concentric rings in the form of a cone (Fig. 17-9b) grids of T bars or other structural shapes (Fig. 17-9c) flat metal perforated plates supported or reinforced with structural members (Fig. 17-9d) dished and perforated plates concave both upward and downward (Fig. 17-9e and f). The last two forms are generally more economical. 

The crude nitrile (about 290 cc.) is placed at once (Note 3) in a 25 cm. evaporating dish, and 425 cc. of c.p. concentrated hydrochloric acid (sp. g. 1.19) is added. The hydrolysis is allowed to proceed in the cold (Note 4) for about twelve hours, after which the mixture is heated on a steam bath to remove the water and excess hydrochloric acid. After heating for five to six hours it is advisable to cool the mixture (Note 5) and... 

To the white residue (Note 1) are added 25 g. of 98-100% formic acid and 2-3 drops of concentrated nitric acid. The mixture is heated for 24 hours on a steam bath. The resulting syrup is dissolved in 100 ml. of water and, with the temperature at 50°, is carefully treated with 25 g. of anhydrous sodium carbonate. The solution is then placed in an evaporating dish and evaporated to dryness on the steam bath. The residue is extracted twice by boiling it with 200-ml. portions of absolute ethanol, and the alcohol solutions are filtered. The alcohol is removed by evaporation and the residue triturated with 100 ml. of a mixture of equal... 

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