The average solar radiation curve as a function of time registered for the month of May, 2012 and its
representative equation are presented in Figure 2. The maximum average radiation, 987.4 W/m2 was
observed approximately at 14:00 hours. The corresponding total energy over the collector surface was
6.40 kW/m2h.The average temperatures versus the time of the day are presented in Figure 3. The highest temperature
at the entrance of the drying chamber was 66.3 °C; the temperature measured at the product was 63.5 °C,
and at the outlet of the chamber, 58.4 °C. These values were registered at 14:00 hours and coincided with
the value of highest solar radiation. The environmental temperature at the time was 26.8 °C, which was
also the highest value registered during the period of experimentation. The difference in temperature
between the inlet and the outlet of the chamber was not constant through the day, early in the morning thedifference was a minimum of 1.4 °C. The highest gradient was registered around 15:00 hours, as 8.7 °C.
The temperature at the outlet of the chamber at the end of experimentation was 32.2 °C.The average mass flow of air registered at the drying chamber is presented in Figure 4. The larger value
of mass flow was 0.0276 kg/s and occurred in May, in April it was only 0.0228 kg/s. All of these
measures corresponded to a time close to 14:00 hours.
The average of moisture content of the chickpeas was de 0.52 kg water/kg dm (dry mass), at the end of
the drying process was of 0.02 kg water/kg dm both experimental months, these results are shown in Fig.
5.In April, it took 40 hours to complete the process whereas in May it only took 32 hours. The drying
time was directly dependent on the solar radiation captured on the cover of the drier. At the beginning of
the process in both months the mass variation was similar but after 7 hours, the chickpeas lost their
humidity at a higher velocity in the month of May, and this difference was kept until the end. The highest
drying velocity was 0.186 kg water/kg dm h, and was observed at the beginning of the process; afterwards
it remained constant at the value of 0.012 kg water/kg dm h in April, and 0.005 water/kg dm h in May. At
this time we could not find reported data to make a sound comparison of results.Experimental data were fed to each of the numerical models presented in Table I. The exponential
model described the best the performance of the drying process, complying with the two imposed criteria.
The graph of the numeric model obtained for the month of April is presented in Fig.6 and May in Fig. 7.
The equations of the exponential numerical model for both experiments performed are presented in
Table II, in all cases this model was the better result for the imposed conditions of