Page 182 - Design of Solar Thermal Power Plants

3.3 THERMAL PERFORMANCE OF PARABOLIC TROUGH COLLECTOR 167

TABLE 3.6 Calculation of Hourly Useful Thermal Collection of Solar Collector [23]

Time/ T a / G/(W/ G bp / Dt/G/ q/ (q u /A g )/
2 2 2 2
K sa
h C m ) (W/m ) (m K/W) ( ) (W/m )
6 25.56 41 0 0.5141 93.4 0 0
7 26.11 189.24 116.7 0.1086 79.6 0.58 0
8 26.67 394.24 305.93 0.0507 66.2 0.84 78.85
9 29.44 583.48 488.86 0.0296 53.5 0.93 252.31
10 31.11 731.71 633.94 0.0211 42.5 0.96 381.63
11 32.78 826.33 728.56 0.0167 33.4 0.98 469.94
12 33.33 861.02 763.25 0.0155 30 0.98 498.32
13 34.44 826.33 728.56 0.0148 33.4 0.98 476.24
14 35.56 731.71 633.94 0.0187 42.1 0.96 400.55
15 36.11 583.48 488.86 0.0181 53.5 0.93 280.7
16 36.11 394.24 305.93 0.0264 66.2 0.84 119.85
17 35.56 189.24 116.7 0.0593 79.6 0.58 0
18 35 41 0 0.2851 93.4 0 0

q u , useful energy.

comparing parameters themselves that have been obtained through
regression.
Thermal performance test method of solar collector follows a basic
idea. Thermal performance test of solar collector aims at designing a
collector application system. Therefore, it is necessary to take into
consideration main thermal performance characteristics related to the
operation of collectors; by measuring various parameters related to
thermal performance of collector, according to the respective thermal
performance mathematical model, mathematical methods of statistical
regression can be used to identify the undetermined coefficient in the
model; based on the thermal performance model, other physical condi-
tions can be calculated and predicted, such as the whole-day and annual
cumulative useful output energy of collector under solar irradiance,
ambient air temperature and system operating temperature of a specific
day. It is a remarkable fact that along with the increase of influencing
factors for operating conditions of solar collector, it is necessary to use a
more complex mathematical model to describe the respective thermal
performance on a reasonable basis, and further offer the precise whole-
day and annual cumulative output energy of collector under changing
input conditions.