Page 59 - Design of Solar Thermal Power Plants

52 2. THE SOLAR RESOURCE AND METEOROLOGICAL PARAMETERS

China’s topography is high in the west and low in the east, with three
ladderlike distributions:
The top-level region in China’s topography is the QinghaieTibet
Plateau. The QinghaieTibet Plateau has a mean elevation of over 4000 m
2
and land coverage of approximately 2.3 million km ; it is the largest
plateau in the world. It is located in southwest China; a series of huge
mountains with continuous snowy peaks spreads over the plateau from
north to south, including the Kunlun, Altyn Tagh, Qilian, and Tanggula
Mountains; Karakoram and Kailas Ranges; and Himalayas. This region
also has the most abundant solar resources.
Second-level region. Beyond the Kunlun and Qilian Mountains to the
north and Minshan, Qionglai, and Hengduan Mountains to the east of the
QinghaieTibetan Plateau, the elevation rapidly drops to about
1000e2000 m, with some partial areas as low as 500 m. In this second-
level region, the Greater Khingan Range and Taihang Mountains
through Wushan Mountain, and further to the Wuling and Xuefeng
Mountains in the south, serve as the boundary of the eastern margin. Here
spreads a series of high mountains, plateaux, and basins with elevations
over 1500 m from north to south, including the Altai, Tian Shan, and
Qinling Mountains; Inner Mongolian, Loess, and YunnaneGuizhou Pla-
teaus; and Junggar, Tarim, Qaidam, and Sichuan Basins. Except for the
YunnaneGuizhou Plateau and the Sichuan Basin, this is basically the
region with the second-most-abundant solar resources.
Third-level region. Over the Greater Khingan Range and Xuefeng
Mountains, this area directly reaches the coast in the east. Hills and plains
in the region have elevations below 500 m. In the third-level region, from
north to south, spreads the Northeast China, North China, and
MiddleeLower Yangtze Plains; extensive areas of low mountains and
hills lie to the south of the Yangtze River and are generally referred to as
the Southeast China Hilly Regions. In the former area, elevations are all
below 200 m; in the latter, most areas have elevations between 200 and
500 m; only a few hills reach or exceed an elevation of 100 m. This is
basically the region with the third-most-abundant solar resources.

2.4 CALCULATING METHODS FOR SOLAR POSITION

During solar thermal utilization, the normal requirement is to consider
solar radiation as a black body radiator with a temperature of 6000K and a
wavelength of 0.3e3 mm. Solar radiation that reaches the ground is mainly
influenced by astronomical and geographical factors such as longitude
and latitude, elevation, solar declination angle, solar hour angle, air
quality, and weather conditions. Solar radiation can be categorized as
either direct or scattered. Solar concentration mainly utilizes direct