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Unformatted text preview: Celsius. The concentrators must move
to track the sun if they are to perform effectively .
to 2. Concentrating
Concentrating, or focusing, collectors intercept direct
radiation over a large area and focus it onto a small
absorber area. These collectors can provide high
temperatures more efficiently than flat-plate collectors, since
the absorption surface area is much smaller. However,
diffused sky radiation cannot be focused onto the absorber.
Most concentrating collectors require mechanical equipment
that constantly orients the collectors toward the sun and
keeps the absorber at the point of focus. Therefore; there
are many types of concentrating collectors .
are 3. Types of concentrating
There are four basic types of concentrating collectors: Parabolic trough system
Stationary concentrating collectors
Stationary 3.1. Parabolic trough
system Parabolic troughs are devices that are shaped like the
letter “u”. The troughs concentrate sunlight onto a
receiver tube that is positioned along the focal line of the
trough. Sometimes a transparent glass tube envelops the
receiver tube to reduce heat loss .
Their shapes are like letter “u”
as shown figure 3.1.1 below.
as Figure 3.1.1 Crossection of parabolic trough . The parabolic trough sytem is
shown in the figure 3.1.2 below.
shown Figure 3.1.2 Parabolic trough system . Parabolic troughs often use single-axis or dual-axis
The below figure 3.1.3 shows one axis
tracking parabolic trough with axis
oriented Figure 3.1.3 One Axis Tracking Parabolic Trough
with Axis Oriented E-W . The below figure 3.1.4 shows two
axis tracking concentrator.
axis Figure 3.1.4 Two Axis Tracking Concentrator .
Axis Temperatures at the receiver can reach 400 °C and
produce steam for generating electricity. In California,
multi-megawatt power plants were built using parabolic
troughs combined with g...
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- Spring '14