Page 227 - Design of Solar Thermal Power Plants

210 3. GENERAL DESIGN OF A SOLAR THERMAL POWER PLANT

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the same fixed value (such as 800 W/m ). Parabolic trough collectors have
been arranged on the north-south axis, with a length of 100 m. Collector’s
_
output power Q is constant, and the efficiency of collector in case of solar
normal incidence is 60%.
According to the assumption, h Gbp ¼ 60%, and based on

f
G bp ¼ DNI cosðqÞ 1 tanðqÞ
L
_ Q h Gbp G bp
it can be further deduced, that h DNI ¼ DNI A ¼ DNI ¼ h Gbp cosðqÞ
h i
f
1 tanðqÞ
L
The incidence angle is assumed to remain unchanged within each
minute.
1. Cosine value of daily maximum incidence angle, which is shown in
Fig. 3.58.
2. Cosine value of daily mean incidence angle, which is shown in
Fig. 3.59
3. Daily cosine value variation on a typical day, which is shown in
Fig. 3.60, in which 172, 266, and 356 separately refer to the
summer solstice, autumnal equinox and winter solstice.
4. Annual mean corrected value of beam incidence angle
a. Badaling
f

cosðqÞ 1 tanðqÞ ¼ 0:8013
L
Then

f

h DNI ¼ h Gbp cosðqÞ 1 tanðqÞ ¼ 0:6 0:8013 ¼ 0:4808
L
b. Sanya
f

cosðqÞ 1 tanðqÞ ¼ 0:9209
L
Then

f
h DNI ¼ h Gbp cosðqÞ 1 tanðqÞ ¼ 0:6 0:9209 ¼ 0:5525
L
c. Hohhot

f
cosðqÞ 1 tanðqÞ ¼ 0:7971
L