Utilization of Solar Tunnel Dryer for Drying of Fodder Crop

A solar tunnel dryer of 200 kg capacity was utilized for drying of fodder crop. The dryer is having size 14.24 × 3.34 × 2 m (L × W × H) with G.I. pipe frame structure was covered with UV stabilized 200 μm transparent sheet. The solar tunnel dryer consisted of solar collector section and drying section. In drying section 8 trays with mesh bottom in which 4 trays having step like structure of size 3 × 1.2 × 1.1 m and 4 trays of size 3 × 1.2 × 0.6 m were used to facilitate the loading and unloading of the products. For ventilation 4 chimneys having 0.30 m diameter and 0.70 m height were provided with 2 AC exhaust fans. A provision of north wall of size 14.24 × 1 m was provided to minimize heat losses. At no load condition, temperature inside the solar tunnel dryer with respect to time achieved its peak value at absorber plate was found to be 52.1 0C at 13:05 of the day whereas the atmospheric temperature was about 36.1 0C. The drying time required for fodder crops dried from moisture content of 80-90 % (w.b) to attain safe moisture content of 8-10 % (w.b) is 6.5-8 hours and 16-18 hours in solar tunnel dryer and open sun drying respectively. The results showed that the drying rate of fodder crop under solar tunnel dryer was found to be improved during initial phase of drying due to higher moisture diffusion.