Experimental investigation on performance of small passive solar greenhouse dryer for cashew kernel drying

Cashew is an important dry nut used in India. India is one of the major producers and exporter of cashew kernels. Most of the cashew processing industries in India use steam for cashew kernel drying. Solar greenhouse dryers are useful solar technologies in developing countries like India. The objective of this study is to investigate experimentally the performance of the solar greenhouse dryer for cashew kernel drying for adapting it to small scale cashew processing industry working in batches. A small solar greenhouse dryer is designed and developed using multi wall polycarbonate sheets as glaze for drying cashew kernels under passive conditions. Experiments are conducted under meteorological conditions of Udupi (Latitude (φ) 13o15’10” N and Longitude 74o47’39” E). The experimental results have shown drying chamber efficiency of 51.7 % with an average drying rate of 0.158 kg/h. The specific energy consumption of 12.42 kWh/kg and moisture content removal of 1.27 kg (5.26%) is observed. Total reduction in moisture content is found to be 41.2%. Developed unit is found suitable for small scale industries working on batch drying with absolutely no conventional energy input. Experimental results can be used for developing bulk drying units.