The variations of solar radiation, ambient air temperature
and air temperature at the outlet of the collector for
a typical day during solar drying of red chilli are shown
in Fig. 2. The variation of ambient air temperature during
the drying period (February–April, 1999 and 2000) varied
from 20 to 35 C while the air temperature at the outlet
of the collector varied from 40 to 66 C. During the drying
period, air temperature at the outlet of the collector was
observed to be much higher than the ambient air
temperature.
The rise in air temperature at the outlet of the collector
above ambient air temperature against solar radiation, during
solar drying of red chilli, is shown in Fig. 3. The average
air temperature rise at the outlet of the collector over
ambient air temperature was found to be 21.62 C during
solar drying of chilli. It is observed from Fig. 3 that air
t