Page 38 - Design of Solar Thermal Power Plants

1.2 BRIEF INTRODUCTION TO SOLAR THERMAL POWER GENERATION 31

plant, the solar field is composed of the heliostats. In CSP plants with
parabolic dishes the solar field is composed of the parabolic dishes.
9. Parabolic trough collector
A line-focus solar collector that concentrates solar radiation by
means of a reflector with a parabolic cross section. It is composed
of a set of elements that altogether can track the sun as a single
unit.
10. Linear Fresnel collector
A line-focus solar collector that uses reflectors composed of at least
two longitudinal segments with parallel axes to concentrate solar
radiation onto a fixed receiver.
11. CSP plant
Synonymous with solar thermal power and concentrating solar
power plants. A facility that applies solar concentration and
thermodynamic processes to convert direct solar radiation into
electricity suitable for distribution and consumption. The facility
may include further sources of thermal energy, such as fossil fuel or
biomass, in parallel with solar radiation.
12. Concentrator
The part of a solar collector composed of reflecting or refracting
elements that concentrate and redirect beam solar radiation onto
the receiver.
13. Useful solar irradiation
The integral of the useful radiant solar power over the time interval
considered, measured in kWh (1 kWh ¼ 3.6 MJ).
14. Heat transfer fluid
Fluid used to carry heat from one system component to another in
a CSP plant.
15. Heliostat
A system that reflects beam solar radiation toward a
predetermined fixed target by means of a single reflecting element
or a set of reflecting elements (facets) controlled by a two-axis solar
tracking system.
16. Solar collector aperture area.
The maximum projected area that accepts solar radiation. The
geometrical dimensions of heliostat and parabolic trough
concentrators are separately shown in Fig. 1.16 (in which the side
length of a single heliostat is c) and Fig. 1.17. For a heliostat, the
2
concentrator aperture area ¼ 64 c , and the concentrator’s
contour aperture area ¼ a b. As shown in Fig. 1.17, a parabolic
trough concentrator consists of 7 12-meter-long units with a unit
length of c and a total length of a with concentrator aperture
area ¼ 7 b c and concentrator contour aperture area ¼ a b.