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solar radiation. Typically, a natural gas-fired heat or a
gas steam boiler/reheater is used. Troughs also can
be integrated with existing coal-fired plants .
be 4.2. Dish Systems
4.2. Dish systems use dish-shaped parabolic mirrors as
reflectors to concentrate and focus the sun's rays onto a
receiver, which is mounted above the dish at the dish
center. A dish/engine system is a stand alone unit
composed primarily of a collector, a receiver, and an
engine. It works by collecting and concentrating the sun's
energy with a dishshaped surface onto a receiver that
absorbs the energy and transfers it to the engine. The
engine then converts that energy to heat. The heat is
then converted to mechanical power, in a manner similar
to conventional engines, by compressing the working
fluid when it is cold, heating the compressed working
fluid, and then expanding it through a turbine or with a
piston to produce mechanical power. An electric
generator or alternator converts the mechanical power
into electrical power.
into Each dish produces 5 to 50 kW of electricity and can
be used independently or linked together to increase
generating capacity. A 250-kW plant composed of ten
25-kW dish/engine systems requires less than an
acre of land. Dish/engine systems are not
commercially available yet, although ongoing
demonstrations indicate good potential. Individual
dish/engine systems currently can generate about 25
kW of electricity. More capacity is possible by
connecting dishes together. These systems can be
combined with natural gas, and the resulting hybrid
provides continuous power generation .
provides The right figure 4.2.1
shows the combination of
parabolic dish system.
parabolic Figure 4.2.1 Combination of parabolic dish system . 4.3. Central Receiver Systems
Central receivers (or power towers) use thousands of
individual sun-tracking mirrors called "heliostats" to
reflect solar energy onto a receiver locate...
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- Spring '14