Page 190 - Design of Solar Thermal Power Plants

3.3 THERMAL PERFORMANCE OF PARABOLIC TROUGH COLLECTOR 175

passing through the parabolic trough collector, the solar DNI G p under
averaging effect can be expressed as

G DN ðsÞþ G DN ðs þ s s Þþ G DN ðs þ 2s s Þþ /

G p ¼ p (3.70)
þG DN ½s þðp 2Þs s Šþ G DN ½s þðp 1Þs s Š
G DN in Eq. (3.68) is replaced with G p , and it is substituted into
Eq. (3.54), then

2
d T fo dT fo dT fi
þ A þ BðT fo T fi Þ¼ C þ½E 0 I 0 ðqÞþ E 1 I 1 ðqÞþ E 2 I 2 ðqފ
ds 2 ds ds
2
G p FðT fi T a Þ GðT fi T a Þ
(3.71)

3.3.3.5 Dynamic Test Model and Parameter Identification
Product of G p and I 0 (q) is referred to as G eni , and both sides of Eq. (3.71)
are divided by this variable. In addition, in terms of experimental data,
2
2
the second derivative d T fo ds in Eq. (3.71) may bring uncertainty to the
prediction results of dynamic test model, which thus can be removed. So,
the ultimate expression of thermal performance dynamic test model of
parabolic trough solar collector is

T T fi q q 2 1 dT fo 1 dT fi
fo
¼ e 0 þ e 1 þ e 2 þ a þ b
G eni cosðqÞ cosðqÞ G eni ds G eni ds
(3.72)
2
fi
T T a ðT T a Þ
fi
þ c þ d
G eni G eni
in which
E 0
e 0 ¼
B
E 1
e 1 ¼
B
E 2
e 2 ¼
B
A
a ¼
B
C
b ¼
B
F
c ¼
B
G
d ¼
B