Page 202 - Design of Solar Thermal Power Plants

3.3 THERMAL PERFORMANCE OF PARABOLIC TROUGH COLLECTOR 187

140
D
120 M
100
Output Power ( kW ) 60
80

40
20

0
-20
10:30 10:40 10:50 11:00 11:10 11:20 11:30 11:40
Time ( HH:MM )
FIGURE 3.40 Prediction of dynamic model on collector output power under experi-
mental condition III.

relative error of outlet temperature of heat-transfer fluid within the
parabolic trough collector predicted by the dynamic test model has
exceeded 5%, but the relative error has still mainly concentrated within
2%; in addition, it has always had approximate symmetric fluctuation
around zero.
According to the variation of parabolic trough collector output power
within a range of 15e110 kW calculated on the basis of the experiment
measured value, as shown in Fig. 3.40, in the predicted value of dynamic
test model on parabolic trough collector output power, there are indi-
vidual data points that are less than zero. This is obviously incorrect. It
has also indicated that in case of significant fluctuation of solar DNI,
dynamic test model is not able to ensure the precision of every transient
value of parabolic trough collector output power.
Based on test conditions under Experimental Condition III, by
comparing the predicted value of thermal performance dynamic test
model of parabolic trough collector and the experiment measured value
as well as the respective calculated value, absolute error, and relative
error, they all indicate that in case of being influenced by adverse con-
dition of frequent obnubilation, the dynamic test model is not able to
ensure the high precision of every transient predicted value. However, its
predicted data are able to fluctuate around the measured value, so that the
long-term thermal performance prediction effect of parabolic trough
collector can be ensured.