Performance of Evacuated Tube Collector Solar Dryer with and Without Heat Sources

The objective of present study is to design and fabricate a solar dryer with evacuated tube collector with and without heat storage material (gravel). The performance of solar dryerfor drying chilli under themeteorological condition of Thanjavur, Tamilnadu, India was investigated. The designed dryer compared withnatural sun drying. Drying of chilli in the designed dryer reduced the average initial moisture content from87.36% to a final moisture content of 3.4% in10hours with heat storage material against 12 hours in the dryer without heat storage material and 32 hours in natural sun drying.The designed dryer reduced the durationof drying period up to 66%. The efficiency of the dryerwith heat storage material, without heat storage materialand natural sun drying are found to be 34.23, 22.03 and 9.32%, respectively. The specific moisture extraction ratio of the designed dryer with heat storage material is 0.345 kg/kWh.The quality of the dried chilli in the designed solar dryer is high in terms of colour, odour and flavour. From the performance, quality and quick rate of drying it is evident that solar dryer with evacuated tube collector assisted with heat storage materialis more compatible than other modes of drying