Temperature and solar radiation were recorded every
15 min using a computer connected to a Mac-14 data
acquisition system. Type J thermocouples (Cole–Parmer)
with a accuracy of ±0.5 C were placed in the collector
and the drying chamber. Six thermocouples were fixed to
the solar collector, distributed in the inlet, middle, and
air outlet; these thermocouples were utilized to determine
variations in air temperature as the air passed along the
plate. In order to evaluate radiative and convective losses,
3, 2, and 1 thermocouples were fixed in the system of covers,
bottom plate, and edges of the solar collector, respectively.
5 thermocouples were fixed inside the drying
chamber, distributed in the drying chamber air inlet, upper,
middle, and lower parts of the chamber, and the saturated
air outlet. Incident global solar radiation was recorded on a
local level using a Keep and Zonnen pyranometer with a
sensitivity of 14.69 E103 mV. Air velocity in the collector
channel and drying chamber, as well as wind speed on the
surface of the collector, were measured using a Hot-Wire
Thermo-Anemometer (Cole–Parmer) with an accuracy of
±0.03 m/s.