106
K. V. S. Teja et al.
Fig. 7.4 Comparison of
overall efficiency for case 1
and case 2 from sunrise to
sunset for June
6:00
9:00
12:00
15:00
18:00
0.18
0.20
0.22
0.24
0.26
0.28
Overall Efficiency (%)
Time of the day (hr)
without losses
with losses
Fig. 7.5 Comparison of
various parameters versus
time of the day for June
when convection and
radiation losses through
collector roof are accounted
6:00
9:00
12:00
15:00
18:00
0
20
40
60
80
100
120
140
Time of the day (hr)
Temperature at turbine inlet (
o C)
Collector efficiency (%)
Velocity at turbine inlet (ms
-1 )
Power output (kW)
makes it difficult to predict when the overall efficiency will be maximum. Variation
of all the parameters with time for case 2 can be observed in Fig. 7.5.
7.3.3 Collector Radius
Keeping chimney height as 200 m, chimney radius as 5 m, varying the collector
radius from 100 to 300 m, all the parameters were calculated for 21st June 11:00 to
12:00. From Figs. 7.6, 7.7 and 7.8 it is observed that as collector radius increases, the
temperature and velocity at the chimney inlet increase almost linearly. Also, power