Page 85 - Design of Solar Thermal Power Plants

74 2. THE SOLAR RESOURCE AND METEOROLOGICAL PARAMETERS

TABLE 2.9 Seasonal Weather Factors of Dunhuang
Month January April July October
INDEX
Sunshine percentage/% 77 71 70 82
Sunshine duration/h 232.1 282.4 318.9 280.8
Ground mean 9.9 16.0 31.5 10.4

temperature/ C
Mean precipitation/mm 0.5 2.4 15.2 0.8
Relative humidity/% 46 31 43 45
Mean wind speed/(m/s) 2.2 3.3 2.9 2.3

of which the summer season accounts for 63.9% and winter for only 7.5%,
while annual evaporation can be as high as 2400 mm; and (3) distinctive
seasons, with a winter that is longer than summer as well as huge day and
night temperature differences. The annual temperature variation is as

high as 34 C. During most of the year, Dunhuang experiences east and
northwest winds with a surface mean wind speed of 3 m/s. Hot-dry
winds and black sandstorms are major natural disasters.
Dunhuang is located at the junction of Gansu, Qinghai, and Xinjiang,
with the Qilian Mountain to the south, Mazong Mountain to the north,
2
and Gobi deserts to the east and west with an oasis area of 1400 km , thus
accounting for just 4.5% of the total area. The total cultivated land area of
2
4
the entire city is 1.7747 10 hm , accounting for 12.68% of total oasis
area. The annual mean temperature of the area is 9.5 C; the effective

accumulated temperature over 10 C for the year is 3605.9 C, and sun-
shine duration is 3246.7 h. Values based on the respective seasonal
distribution are shown in Table 2.9.
2.5.4.2 Solar Radiation in Dunhuang
The Dunhuang area features strong solar radiation and abundant
sunshine resources. Meteorological authority observations for multiple
years indicate that the annual sunshine duration of Dunhuang city can
reach 3246.7 h with a sunshine percentage of 75%, global annual radiation
2
2
of 6882.27 MJ/m , and daily mean radiation of 18.86 MJ/m ; it is a region
of China with abundant solar energy resources.
2.5.5 The Solar Resource in Turpan

Turpan city is located in the eastern Xinjiang Uygur Autonomous Re-
gion, south of Bogda Mountain’s main peak in the mideastern Tian Shan