Page 52 - Design of Solar Thermal Power Plants

1.2 BRIEF INTRODUCTION TO SOLAR THERMAL POWER GENERATION 45

2. Collector field efficiency. This is the ratio of the energy obtained by the
heat transfer medium from the collector field to the incident solar
direct normal radiation energy on the aperture of the collector field.
This value represents the ratio of energy, not the ratio of power. A
collector field consists of a concentration field and corresponding
receivers.
3. Collector field annual efficiency. This is the ratio of the total thermal
energy obtained by the heat transfer medium from the collector field
within a year to the total incident solar direct normal radiation
energy on the aperture of the concentration field.
4. CSP plant annual efficiency. This is the ratio of annual power
generation of the CSP plant to the solar direct normal irradiance
transmitted to the mirror surface of the concentration field.
Comparisons between several efficiency values of the Beijing
Badaling tower power plant and the 10 MW Solar Two tower in the
United States are shown in Table 1.8.

TABLE 1.8 Comparison of Annual Mean Performances of Solar Thermal Power
Generation Systems

Solar
Badaling Two Badaling Solar
Item Tower Tower Item Tower Two
Power plant 1 10 Annual mean 68.7 50.3
scale/MW efficiency of the
concentration
field/%
Heliostat 100 40/95 Receiver 85 76
area/m 2 efficiency/%
Total aperture 10,000 81,400 Steam turbine 22.3 32.6
area of the efficiency/%
concentration
field/m 2
Thermal storage 1 3 House power 12 17
capacity consumption
(full-load rate of power
generating plant/%
duration)/h
Operational 400 565 Annual mean 8.35 7.9
temperature power
of steam generation
turbine/ C efficiency/%

Operational 2.8 10
pressure of steam
turbine/MPa