Drying experiments of red pepper in the open-sun and the
greenhouse dryer were carried out in September in 2013. The
hourly variation of solar radiation on horizontal surface during
the experimentation is shown in Fig.2. The solar radiation on
the horizontal surface outside the greenhouse dryer reached
808 W/m2 (Fig.2). The Plexiglas cover transmitted about 85%
of the incident solar radiation. The solar radiation energy is
maximum at midday and minimum at evening.
Air relative humidity under the greenhouse, ambient air
and drying air temperatures inside the greenhouse dryer are
shown in Fig.3. The temperature of ambient air ranged from
21.25 to 35.71 °C. The drying air temperature recorded inside
the greenhouse ranged from 29.21 to 49.88 °C. The relative