Page 148 - Design of Solar Thermal Power Plants

3.2 HELIOSTAT FIELD EFFICIENCY ANALYSIS 133

Solar radiation

Atmospheric particle

Scattering
radiation
FIGURE 3.5 Atmospheric aerosol attenuation.

sand dust particles correspond to visible light and near-infrared
light, which shall be handled by applying the Mie-Debye scattering
theory. The Mie-Debye scattering, on the other hand, mainly relies
on various characteristics, like the size of the scattering particle,
density distribution and refractive index; the relationship between it
and the wavelength is much less intensive than the relationship with
Rayleigh scattering (which can be approximately deemed as
irrelevant to wavelength).
According to the IPCC report, the mean life of sand dusts is about
4 days, the mean column-perpendicular integral content is about
2
32.2 mg/m , and the mass extinction coefficient when wavelength is
2
0.550 mm is 0.7 m /g. Based on the research analysis results,
particles within a range of 0.1e1.0 mm are the main light extinction
particles. NIU Shengjie et al. entered into desert sources (Tengger
Desert, Badain Jaran Desert, Mu Us Desert) during April to May
every year from 1996 to 1999, and conducted systematic
observations toward the sand dust weather; by utilizing a plane to
observe atmosphere aerosols in desert areas, they also
systematically analyzed the microstructure of sand dust aerosols in
Helan Mountains. ZHANG Wenyu et al. conducted the ground
multiwave band solar radiation observations in Shapotou Station in
Tengger Desert during April to September 2001. According to their
research, optical thickness of local atmospheric aerosols varied
significantly under different weather conditions. On April 6, 2000,
during the catastrophic sandstorm, according to the analysis on
sand dust particles, concentration of coarse particles (d > 2 mm)