Unformatted text preview: as turbines .
Parabolic trough combined with gas turbines is shown
figure 3.1.5 below.
figure Figure 3.1.5 Parabolic trough combined with gas turbines . Cost projections for trough technology are higher than
those for power towers and dish/engine systems due in
large part to the lower solar concentration and hence
lower temperatures and efficiency.However with long
operating experience, continued technology
improvements, and operating and maintenance cost
reductions, troughs are the least expensive, most
reliable solar thermal power production technology for
near-term 3.2. Parabolic dish
systems A parabolic dish collector is similar in appearance to
a large satellite dish, but has mirror-like reflectors
and an absorber at the focal point. It uses a dual
axis sun tracker .
The below figure 3.2.1 shows
crossection of parabolic dish.
crossection Figure 3.2.1 Crossection of parabolic dish . The Parabolic dish collector is
shown in the below figure 3.2.2.
shown Figure 3.2.2 Parabolic dish collector with a mirrorlike reflectors and an absorber at the focal point
[Courtesy of SunLabs - Department of Energy] . A parabolic dish system uses a computer to track the sun
and concentrate the sun's rays onto a receiver located at the
focal point in front of the dish. In some systems, a heat
engine, such as a Stirling engine, is linked to the receiver to
generate electricity. Parabolic dish systems can reach 1000
°C at the receiver, and achieve the highest efficiencies for
converting solar energy to electricity in the small-power
capacity range .
capacity The right figure 3.2.3
shows the solar dish
stirling Figure 3.2.3 Solar dish stirling engine . Engines currently under consideration include Stirling
and Brayton cycle engines. Several prototype
dish/engine systems, ranging in size from 7 to 25 kW
have been deployed in various locations in the USA.
High optical efficiency and low start up losses make
dish/engine systems the most efficient of all solar
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- Spring '14
- ........., Concentrating solar power, power tower